Safety of winch launch vrs. aero tow?
Gary Boggs
What do the statistics show is the safer method of launch? Aero tow seems
to involve more inherent dangers to me. For one thing, there is just more
time for things to go wrong. What could be more dangerous than to tie tow
airplanes together and try to fly?
Gary Boggs
Peter Seddon
Having both winched and aerotowed several times!!! I find an aerotow less
demanding, everything happens very quickly on a winch wire.
Peter S
DLA
"Gary Boggs" <gary....@charter.net> wrote in message
news:vplkja9...@corp.supernews.com...
Chris Nicholas
Harry Enfield (a UK comedian): "Flying is safe, you don't want to worry
about flying; it's crashing that's dangerous."
Winch launching and aerotowing are safe, it's the consequence of
mismanaging an abnormality that's dangerous.
Winch launches yield few accidents in themselves (e.g. occasional ground
loops); a competent pilot should have been trained in, and able to cope
with, a variety of abnormal situations such as cable breaks, too slow,
gradual power failure, etc. All of these are manageable with competent
handling. If badly handled, however, any can lead to a bad, even fatal,
accident. E.g. turning too low and slow after a cable break, leading to
a classic spin. But is that counted as a winch accident, or a failure to
monitor speed while turning close to the ground, i.e. a flight or
pre-landing accident? You may find that statistics are not compiled in
comparable ways over time, or between one club (or organisation, or
country) and another.
Aerotowing is more likely to kill the tug pilot than the glider pilot if
it goes wrong, i.e. the "tug upset" accident which seemed to start in
the 1970's. In terms of accidents per 100,000 launches, however, these
are rare. Oversimplifying to some extent, the only really dangerous
part of an aerotow where the competent glider pilot has little chance of
avoiding a bad accident is a rope break or power failure over bad
terrain, which is only applicable to a small proportion of sites (in my
experience).
Either method can lead very rarely to harm to second or third parties. I
know of one fatality to a ground handler associated with cable launch
operations (UK, 1970's). I know of other injuries from falling cables,
including one dead cow. There has probably been at least one instance
of somebody walking into a tug propellor, somewhere in the world. I
recall one tug accident where a child was a passenger in the tug and was
killed when it spun in (there is an argument for never carrying extra
people in the tug unless required for operational or training reasons -
it adds to the risk by reducing climb performance and increasing the
period of greatest hazard, as well as adding to the number of people at
risk in the operation - but many clubs seem to regard that as
acceptable).
There are some underlying causes of accidents that are more likely to be
found in the winch launch phase that in an aerotow - but could anyway
happen in the subsequent flight. A loose seat back leading to unintended
pitch up, and structural failure, are two I have heard of - winch
launches usually involve greater stresses and more extreme attitudes
than aerotows, unless the latter involve rotor or other adverse
conditions. But the subsequent flight could also have included
turbulence or other stress-inducing circumstances with equally tragic
results, if the problem had survived the launch phase - so should those
be counted as launch accidents?
Beware of the raw statistics.
Chris N.
Mark Navarre
"hung out to dry" with no risk whatsoever to the winch driver. During aerotow,
the tug pilot is not likely to make mistakes that might kill himself. The
incentive for a safe tow is thus higher for aerotow, because the tow pilot has
built-in accountability. I have driven the winch, and launched my glider by
tug, winch, and auto-tow. I prefer airtow over the other methods, but all can
be safe with proper training and pre-launch briefing.
-
Mark Navarre
ASW-20 OD
California, USA
-
Eric Greenwell
glide...@aol.com.post says...
> Errors on the part of the winch driver may leave the glider pilot completely
> "hung out to dry" with no risk whatsoever to the winch driver. During aerotow,
> the tug pilot is not likely to make mistakes that might kill himself.
Of course, the winch operator can't make mistakes that will kill him
or her. In addition, I think a major advantage of the winch launch is
the glider pilot can't kill the winch operator! Unfortunately, tug
pilots have put themselves at risk (and been killed because of it)
because of a concern for the glider pilot that is putting the tug
pilot at risk. Sometimes this is just running out of fuel because they
don't want to slow down the launch line; sometimes it's hesitating to
pull the release when low over bad ground.
Personally, I suspect the glider pilot is a little better off behind a
towplane (might be my US training bias), but I have no idea if the
statistics agree with me. The UK and Europe might be able to do a good
comparison, but in the US, winch launching is done in only a few
places.
--
!Replace DECIMAL.POINT in my e-mail address with just a . to reply
directly
Eric Greenwell
Richland, WA (USA)
Bob Johnson
I don't think the winch op can't leave anybody out to dry except maybe
himself. If the glider pilot doesn't like what's happening, pull
release, pull spoilers, land straight ahead.
BJ
Bill Daniels
I have done a whole lot of both and, given a choice, I'll take winch launch.
Yes, things happen fast on a winch launch but then the launch is over in
30-40 seconds so the risk exposure is short - with air tow, you are at risk
a least ten times as long. Air tow in turbulent air is fatiguing - you will
never get tired in a 35 second winch launch.
If you don't like the way a winch launch is going, release and land. You
can do that with a winch launch because you should always be in a position
to land back on the runway - I can't say that is always true with air tow.
Air tow is formation flying - involving two extremely mis-matched aircraft -
with a rope tying them together. This requires highly developed flying
skills to do safely. We teach this to pre-solo students. (I wonder how we
get away with it.) Winch launch can easily be taught to pre-solo pilots
since it is a simple, repetitive task.
Air tow has two aircraft at risk and at least two pilots - winch launch has
only one aircraft at risk.
Winch launch accelerates the glider far faster than air tow so dropping a
wing due to insufficient aileron control is unlikely. (Of course, you can
still drop a wing due to incompetence with unhappy results.)
In both cases, the training of the pilots and launch crews have a lot to due
with overall safety. There is ample opportunity for either to come to a bad
end. With equally good training, I think winch launch is safer.
But, lets face it - winch launch LOOKS scary to a pilot trained that a steep
nose-up attitude near the ground is dangerous. It isn't dangerous but it
sure looks that way.
Bill Daniels
BTIZ
coordination..
BT
"Bob Johnson" <robj...@cox.net> wrote in message
news:3F9B3265...@cox.net...
Bob Johnson
BJ
Bob Johnson
Proper pilot life-saving reaction to winch line breaks, op inattention,
winch engine failure, or op incapacitation is routinely taught in ground
launch training.
How many airtow instructors pull the release on their student at 200 ft
over the outbound fence? Just once? Several times?
BJ
Gary Boggs
required in a winch launch, and the faster acceleration, and the fact that
you are in a position to land on the runway that you are using at all times,
the winch launch would be safer, but I still see no statistics! Come on
folks, someone surly has crunched the numbers. Training is crucial in both,
but what I'm looking for is numbers, I have plenty of opinions myself.
Boggs
"Bill Daniels" <n22...@earthlink.net> wrote in message
news:R3Hmb.2522$Px2...@newsread4.news.pas.earthlink.net...
Bill Daniels
> I like all these points and I suspect that because of the short time
> required in a winch launch, and the faster acceleration, and the fact that
> you are in a position to land on the runway that you are using at all
times,
> the winch launch would be safer, but I still see no statistics! Come on
> folks, someone surly has crunched the numbers. Training is crucial in
both,
> but what I'm looking for is numbers, I have plenty of opinions myself.
>
> Boggs
OK, the BGA accident database is available on the web. The database is
searchable for flights that began with a winch launch. Note, however, that
most of the accidents in this section do not relate directly to winch
launch.
I think that there were only three or four accidents over a ten year period
that actually happened during the winch launch. The rest were accidents
that happened later in a flight that began with a winch launch.
It seems to me that if winch launch accident data is hard to come by, that
in itself is good news. If accidents happened frequently, there would be
lots of hard data.
Bill Daniels
JJ Sinclair
I suspect you are considering winch launching for your club and I would think
the biggest problem would be in getting club members, "Up to Speed" on winch
operations.
In way of illustrating my point, allow me to tell a little story about a local
soaring operation that is no longer in business. This outfit advertised, get
your "Aero-Tow Only" restriction, removed from your glider licence. Come to XXX
Soaring and we will check you out in about an hour, or so. This outfit had a
2-33 with only a nose tow hook (mistake no. 1) They didn't use radios (mistake
no. 2) The flight examiner weighed a good 300 lb. + your average student at 200
lb. = 500 lb's in the 2-33 (mistake no. 3)
I was going to take the course, but had to wait for the student in front of me
to get his check-out. The signal for "Start the launch" was, level the wings
and flash the lights in the car located near the right wing tip. It went
something like this:
1. Level the wings & flash the lights------------Glider rolled about 10 feet
and stopped. winch operator stalled the winch.
2. Level the wings & flash the lights---------- Cable went, but glider didn't
move. In the last attempt, wheel had rolled over cable and caused a reverse
release.
3.Level the wings & flash the lights---------------Glider went about 100 feet
and stopped. Cable had "Kinked" in previous 2 attempts and then broke at a
kink.
-------------30 minute delay while Nico-Press & sleves are found and cable is
spliced. With 3 attempts and no success, student is having second thoughts and
opens canopy and starts to climb out. Instructor tells him, everything will be
fine, this time, Get back in here.
4. Level the wings & flash the lights------------ Glider takes off, to the wild
applause of all those assembled. Glider only gets 400 feet due to nose tow hook
location. Glider makes a 90 right and a 180 left, lands and rolls right up to
the starting point.
Attempts 5, 6 & 7 come off without a hitch and the Flight Examiner is called
out (300 lbs)
Level the wings & flash the lights-------------- Glider takes off, but only
gets 300 feet, makes a modified 90/180 and plunks it down hard, way down the
runway.
I took this opportunity to silently disappear and my licence still reads,
Aero-Tow Only.
JJ Sinclair
Andreas Maurer
>I took this opportunity to silently disappear and my licence still reads,
>Aero-Tow Only.
I have to admit it: I'm impressed.
They really made every mistake that is possible. Thiw "insch launch"
attempts had as much in common with winch launching as a 2-33 has in
common with a Boeing 747.
Bye
Andreas
Mark Navarre
>If you don't like the way a winch launch is going, release and land. You
>can do that with a winch launch because you should always be in a position
>to land back on the runway - I can't say that is always true with air tow.
This brings up a point I left out of my original post. The SITE must be
suitable for winch launching. If the site has a short runway, or obstructions,
then the option to release and land straight ahead may be limited. Of course
this applies to aerotow as well.
>Winch launch accelerates the glider far faster than air tow so dropping a
>wing due to insufficient aileron control is unlikely. (Of course, you can
>still drop a wing due to incompetence with unhappy results.)
If the winch operator does not apply adequate power for rotation and climb
early in the launch, the window of opportunity to abort safely closes quickly
and leaves unsuitable options.
>In both cases, the training of the pilots and launch crews have a lot to due
>with overall safety. There is ample opportunity for either to come to a bad
>end. With equally good training, I think winch launch is safer.
I wholeheartedly agree that training, and practice, are of great importance. I
had a winch launch accident early this year in which training played a large
part. Also reaction time, and the limited suitability of the site for winch
launching.
I will give a brief description of the accident:
I did not brief the winch driver on my launch requirements (mistake 1), my
glider had the highest wingloading of any there that day.
The initial acceleration from a stop was weak enough in comparison to all my
previous training on this winch to make the hair on the back of my neck stand
up. I had enough room to wait for more power (mistake 2) but was too low and
slow to wag wings. I briefly pulled back on the stick to see if there was any
tension on the cable, maybe the winch had redlined in a lower gear (the winch
in question has known issues, mistake 3). I felt the tension completely go
away, pulled the release and pushed the nose over. I was not aggressive with
the push over (mistake 4), but altitude was only 50-75 feet and the glider was
just above stall, so not enough room to gain speed, no room to land straight
ahead, and insufficient altitude to complete a turn to the right for a landing
on the abort runway.
I dragged the right wing and ground looped, breaking the tail boom of my
glider, and narrowly missed a Toyota truck that was parked in an unsafe area.
During debrief, I found out that the winch driver saw the retrieve chute
balloon immediately and thought I released so chopped the winch power. Chute
blossoming was common that day on previous launches due to improper chute
rigging (mistake 5) and this was probably exaggerated by the lack of full power
during the initial part of the launch. The site has about 1000 feet of usable
straight ahead runway, but it is downhill from glider to winch, and a portion
is steep enough so as to be impossible to walk uphill if the dirt is wet. The
abort runway is at a right angle to the launch runway, undulates in elevation
30-40 feet, and has a narrow spot about 60 feet wide bordered by trees and
bushes.
The dimensions of the site are such that there is a point in the launch when
you may be too high to land straight ahead, too low to continue into the ridge
lift, and too low to make the landable portion of the abort runway. The
situation is worse for higher wingloading gliders (I fly an ASW20) than are
typically flown at this site. Some of you may have guessed the site by now, it
is Torrey Pines, California. Having had this experience, I would fly there
again, but only after addressing the training and briefing issues mentioned.
The configuration of this site requires extra special attention to launch
procedures, but the satisfaction of flying at such a unique and historic
location is well worth it.
Ralph Jones
>
>I took this opportunity to silently disappear and my licence still reads,
>Aero-Tow Only.
I have a co-worker who's still around because he made the same shrewd
decision in connection with a bungee-jumping operation...
rj
Bob Johnson
understand Derek Piggott's great book "Ground Launches".
Thanks, Derek!
BJ
Pete Brown
>
> Gary Boggs wrote:
>> What could be more dangerous than to tie two
>> airplanes together and try to fly?
>>
>>Gary Boggs
--
Peter D. Brown
http://home.gci.net/~pdb/
http://groups.yahoo.com/group/akmtnsoaring/
Mike Borgelt
I've only done about two winch launches but have done several hundred
car tows and driven several hundred also.
Ground launches involve lots of wire, rope etc. It is probably a good
observation that the more rope you have the more trouble you can get
into! With one exception below.
I've had the glider run over the wire and tangle in the wheel well.
Not good as you now cannot release and depend on the tow driver..
Pilot reactions to a low altitude winch launch failure are utterly
critical. I suspect we've killed dozens if not hundreds over the years
this way around the world.
You may need more than one launch to get away(rare with aerotow). This
increases your launch risk exposure.
Someone mentioned the stresses in the wire and the glider. Both are
much lower in properly executed arotow.
Aero tow may have a higher exposure to an off airport landing in
unsuitable terrain but the failures seem to be much more rare than
winch wire breaks. If you don't use toy towplanes(less than 180HP)
then any place suitable for winching probably gives you the
opportunity to do a 180 or land straight ahead from an aerotow.
If you want gliding to be popular aerotow involves less running around
on the ground per flight hour.
Flying towplanes is more fun than driving a winch or tow
car.(Allegedly - I last sat in a towplane in 1971 writing down CHT's
for the cooling test for 4 tows in a row and haven't felt motivated to
get into a towplane since despite the aquisition of a PPL 9 years ago)
Aerotowing danger can be reduced by using a longer rope. One of the
local clubs around here tried it and liked it so much the towpilots
won't fly with short ropes. The long rope gives everyone more time to
handle upsets. I suspect the rise of the towplane upset accident
coincided with using shorter ropes.
Mike Borgelt
Bill Daniels
"JJ Sinclair" <jjgl...@aol.com> wrote in message
news:20031026100410...@mb-m11.aol.com...
What JJ experienced is, unfortunately, an all too common experience in the
USA.
A bunch of guys, (it's usually guys) get together and decide to winch launch
gliders. ("How hard can it be?" "We can teach ourselves...") They start
with poor equipment, a bad site, no experience or training and proceed to
scare themselves badly...or worse.
They then decide that the problem is winch launch (It doesn't work, low
releases, lots of hassles, etc..) and then go back to air tow.
I've flown tugs and driven winches - I'll take winches for fun. I've flown
lots of air tow and been scared on plenty of occasions. I've flown lots of
winch launches and rarely had one go wrong. If anybody wants a winch
experienced CFI-G for a week of winch training, email me. I might be
available.
BTW, How about some of our British and European friends with lots of winch
experience jumping in here?
Bill Daniels
Stefan
>> BTW, How about some of our British and European friends with lots of winch
> experience jumping in here?
I can't speak for others, but I read this thread, shaked my head and
simply didn't feel like commenting. Seldom I have seen a discussion
which showed so clearly plain ignorance.
In a word: If done correctly, winch launching is safe, cheap and fun. It
is certainly much (much!) cheaper than aero-tow. It is certainly much
more fun. And it's easier, too.
The only dangerous moment for the pilot is at the very beginning of the
pull. It is very very very important not to pull too early or too
briskly. Stalling the glider at this altitude is lethal. Once
established in the climb, make sure you have always enough speed to pull
over if the rope breaks. Everything else is very easy and very safe.
There *are* rope breaks, but they are very much a non-event. Either you
have enough room to land straight, or you have enough altitude to do a
180 or a short circuit.
Winch launching has much more safety issues for the ground crew and
spectators than for the pilot. Be sure to have an experienced person
show you safe procedures.
Of course, an experienced winch driver helps a lot, too. At our club, a
new winch driver must do 50 launches under supervision befor he's
allowed to winch alone. We never had a winch accident in 40 years.
Stefan
Stefan
>> BTW, How about some of our British and European friends with lots of
winch
>
> experience jumping in here?
I can't speak for others, but I read this thread, shaked my head and
simply didn't feel like commenting. Seldom I have seen a discussion
which showed so clearly plain ignorance.
In a word: If done correctly, winch launching is safe, cheap and fun. It
is certainly much (much!) cheaper than aero-tow. It is certainly much
more fun. And it's easier, too.
The only dangerous moment for the pilot is at the very beginning of the
pull. It is very very very important not to pull too early or too
briskly. Stalling the glider at this altitude is lethal. Once
established in the climb, make sure you have always enough speed to push
Bill Daniels
"Stefan" <stefan@mus._INVALID_.ch> wrote in message
news:3f9c5e76$1...@news.swissonline.ch...
Bill Daniels
E. A. Grens
I, as a power pilot, learned to fly sailplanes on the winch, overseas. I
now only fly aerotow, and am not signed off for ground launch. One thing I
have not seen mentioned is the qualification of winch operators. Tow plane
pilots ( I'm not one) have to meet certain standards and be signed off. I
became a winch operator by volunteering out of club spirit (stupidty?). I
was informally instructed by a winch operator who desparately wanted to
escape the exile of the winch. Then I was left to do the job, getting my
flights at the end of the day. They brought me food and drink
(nonalcholic), but no one "qualified" on the winch would come near for
hours. I'm sure I never endangered any aircraft or pilot, but I'm also sure
that some achieved less than optimal release altitude. There was no
tensionmeter, and throttle control was based on visual evaluation of
aircraft attitude and cable sag.
Many years later I had the chance to observe the operator of a modern
six-reel winch at Terlet. He was an artist at work, and he had the best
equipment.
I think winch launches are safe, as long as you have a cg hook. But, in any
comparison to aerotow, the increased number of launches necessary to achieve
sustained flight must be taken into account.
Ed Grens
John Giddy
| A bunch of guys, (it's usually guys) get together and
decide to winch launch
| gliders. ("How hard can it be?" "We can teach
ourselves...") They start
| with poor equipment, a bad site, no experience or training
and proceed to
| scare themselves badly...or worse.
|
| They then decide that the problem is winch launch (It
doesn't work, low
| releases, lots of hassles, etc..) and then go back to air
tow.
|
| I've flown tugs and driven winches - I'll take winches for
fun. I've flown
| lots of air tow and been scared on plenty of occasions.
I've flown lots of
| winch launches and rarely had one go wrong. If anybody
wants a winch
| experienced CFI-G for a week of winch training, email me.
I might be
| available.
|
| BTW, How about some of our British and European friends
with lots of winch
| experience jumping in here?
Not from UK or Europe, but Australia:
There are a number of clubs, ours included that usually
launch by winch.
In Oz, all gliding is controlled by The Gliding Federation
of Australia, under a delegation from CASA (the Aussie FAA)
GFA has a regulation setting the minimum length of field for
winch launching to 1200 metres (approx 4000 ft). This is to
avoid the possibility of a "non-manoeuvring" area, where, if
the cable breaks, there is insufficient length to land
straight ahead, and not high enough to do a modified circuit
and land normally.
There are standard procedures which are taught, involving
signals between the pilot and the winch driver, and
procedure for dealing with cable breaks. These are taught
and practiced during the winch launch training. There is an
agreed minimum number of launches (12) before sign-off for
anyone converting from aerotow.
Provided you have a good winch, with sufficient power, and
an experienced driver, it is a very safe and efficient way
to get into the air.
It is also quiet, which is a boon for those fields close to
built-up areas.
Cheers, John G.
tango4
"Mike Borgelt" <mbor...@borgeltinstruments.com> wrote in message
news:vfeopvosok0nr9vjl...@4ax.com...
>
> If you want gliding to be popular aerotow involves less running around
> on the ground per flight hour.
>
A cable retrieve winch such as the one in use at the Long Mynd in the UK
makes a winch operation even slicker than aerotowing!
Ian
John Mason
http://www.esgc.co.uk/BGAdata.htm
Search and study the reports. There is much written between the lines. If
you look at the number of accidents where the launch was originally a winch
launch you will find that a lot of accidents occur soon after the launch is
completed and are attributed to other factors but which would really not
have happened if they had aerotowed. (Rigging errors not found in the speed
of the launch, not watching airspeed and spinning after the launch because
of distraction with the high workload of the winch and not dealing with the
angle of attack in the launch properly and so on). It is not possible to
give clear cut statistics without a significant degree of human
interpretation and you will really need to make your own mind up. I am
certain winching is a lot more dangerous. There are more things that can go
wrong and if they can go wrong, they will given time.
"Gary Boggs" <gary....@charter.net> wrote in message
news:vpmlio...@corp.supernews.com...
Jona
Bob;
Right, I thik this is really imprtant.
On tow, at 200 ft over the far-boundary you need the confidence to
know the right thing to do and do it straight away while retaing air-speed.
On tows we take of saying to oursevles 'land-ahead if it breaks now' from 0
to 150 feet
but there is a sweaty bit between150 and 300 ft where the choices are less
attractive.
In a winch lanuch (probably becauseof more experience) I am never in this
sweaty "hope it don't break at just this second" position.
--
Jonathan
Mike Borgelt
So how many winch operations involve two people?
I've had tows where the only people present were the tow pilot and the
glider pilot. Least I got with auto tow was three. Both were no radio
ops.
And for you guys who operate on nice green grass airfields which allow
things like cable retrieve winches - it don't happen in Oz.
And lastly we did have a winch driver killed during a winch launch a
few years ago. The wire (basically high tensile single strand fencing
wire) shattered as it was being reeled in after the glider released
and one of the pieces of shrapnel hit the winch driver in the upper
torso and he died shortly thereafter before anyone got to the winch.
The lexan shield had been bought but not installed.
My favourite launch method involves a motor in the glider.
Mike Borgelt
Silent Flyer
> >"Mike Borgelt" <mbor...@borgeltinstruments.com> wrote in message
> >news:vfeopvosok0nr9vjl...@4ax.com...
>
> things like cable retrieve winches - it don't happen in Oz.
>
You have obviously never been to the Long Mynd - I have heard it described
rather unkindly) as " a barely levelled granite hilltop".
The retrieve system ( a small winch pulls the cable back to the launch
point) originated out of necessity many many years ago when the airfield was
much smaller and the winch had to be positioned outside the boundary. The
cable crossed a deep, (approx 15/20 ft) gully at the airfield boundary and
then on up along a slope covered in bracken and heather, any other method of
retrieving the cable was impracticable. However the system was so efficient
in terms of launch rates that it has continued to this day even though the
airfield is now big enough to site the winch within the boundary. There is
of course a small penalty in terms of launch height but this is of little
significance.
Owain Walters
my flying is from winch launching.
My club operates primarily from the winch launch. When
our club was a bit busier we completed anything up
to 120 winch launches a day.
Winch launching, like anything in flying, is completely
safe if people are trained properly. I am not going
to teach people how to winch launch over the internet
but I will say that the number one rule is never to
get yourself into a situation from which you can not
recover with the energy (whether kinetic or potential)
you have. Put simply - never climb steeply from the
ground, always maintain an shallow 'initial' climb
until you reach a safe height and speed.
Winch launching is more Labour intensive than aerotowing
as you need a winch-driver, a cable retrieve driver,
a competent and experienced person making the decisions
and supervising and a wingrunner. However, for a training
environment it is certainly much, much cheaper and
fosters a 'club' atmosphere as everyone relies on eachother
to make things happen.
I do not know any statistics of winching vs. aerotowing
and frankly I think that statistics are, in general,
irrelevant in gliding (just look at the US contest
finish stats, I counted 4 in the last 17 years but
people think this is an area out of control in the
US). But what I do know is that I have never been in
a situation where I could not land safely on the airfield
in the event of a launch failure and I have never just
cleared the boundary hedge by a matter of inches (my
gratitude to the tug pilot for not dumping me has been
expressed many times in the form of beer) in a Duo
full of water on a winch launch either.
Having said that,I also feel that aerotows are also
safe when given that the equipment is regularly inspected
(whether it be the tug or rope) and that the landing
options are fully researched/explained prior to take
off. I have never not considered an aerotow because
I felt it was unsafe.
I guess my point is that both types are utterly safe
if people are trained and have a plan if things go
wrong, again like most situations in flying.
Bill Daniels
"John Mason" <replytothe...@nospamthanks.com> wrote in message
news:bninqa$e6f$1...@hercules.btinternet.com...
> A good place for statistics is:
>
> http://www.esgc.co.uk/BGAdata.htm
>
> Search and study the reports. There is much written between the lines.
If
> you look at the number of accidents where the launch was originally a
winch
> launch you will find that a lot of accidents occur soon after the launch
is
> completed and are attributed to other factors but which would really not
> have happened if they had aerotowed. (Rigging errors not found in the
speed
> of the launch, not watching airspeed and spinning after the launch because
> of distraction with the high workload of the winch and not dealing with
the
> angle of attack in the launch properly and so on). It is not possible to
> give clear cut statistics without a significant degree of human
> interpretation and you will really need to make your own mind up. I am
> certain winching is a lot more dangerous. There are more things that can
go
> wrong and if they can go wrong, they will given time.
>
John, the only way to see the data in the way you suggest is with a
prejudiced eye. If a pilot can't fly a glider under stress or rig it
properly, he's just an accident looking for a place to happen. It doesn't
matter how the glider is launched.
Bill Daniels
Bert Willing
cable breaking near the winch under full power is something very, very
dangerous, so sitting on a winch without shielding is asking to be killed.
The min team for winch launches is the pilot, the winch driver and the wing
runner (the winch driver can retrieve the cables on his own if the winch has
properly working brakes on the drums). If pilot and winch driver are
suffiencently experienced, a chair may well replace the wingrunner (although
stating that in public may not be politically correct :-)
During winch launch, any accident is related to pilot errors so you can
basically keep the accident rate fairly low.
On aerotows you may have situations were a cable break *will* induce an
accident, and the pilot may just be able to influence the damage.
--
Bert Willing
ASW20 "TW"
"Mike Borgelt" <mbor...@borgeltinstruments.com> a écrit dans le message de
news:2hvppvs4f2lsf2qni...@4ax.com...
Martin Gregorie
<replytothe...@nospamthanks.com> wrote:
...snippage...
>(Rigging errors not found in the speed
>of the launch, not watching airspeed and spinning after the launch because
>of distraction with the high workload of the winch and not dealing with the
>angle of attack in the launch properly and so on).
...snippage...
None of these points are unique to winching.
- I've seen many more comments on r.a.s about failed aero tows
due to rigging errors than I've heard about for winching. To me this
says more about the safety culture (or lack of it) at different
sites than anything to do with the launch method.
- incorrect airspeed and stall/spin after release is just as possible
at the end of an aero tow if you overcook the climbing turn.
- AOA mis-management will be *much* more serious during an aero tow
on a CG hook than during a winch launch provided the appropriate
weak link is used. Think tug upset.
I launch both ways though I'll admit to many more winch than aero-tow
starts. I see very little difference in pilot stress levels or
workload between the launch methods in good conditions, but the
overall stress from an aero tow is larger, simply because you're on
tow for 5 minutes or more compared with the 30 seconds to get to the
top of the cable. If I'm flying something as sluggish in roll as a
G.103A in turbulent, windy conditions then winching has a much lower
work load than aero-tow.
This is my opinion entirely: I'm not speaking for anybody else or
trying to put words in their mouth.
--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :
Christian Husvik
John Mason wrote:
> (Rigging errors not found in the speed of the launch,
Whit??
Do forgive my clearly insufficient knowledge of the English
language, but what exactly does "rigging errors not found in the speed
of the launch" mean? And how would those have been found and corrected
if the launch subsequent to rigging had been by areotow rather than by
winch?
I mean: The fact that an aerotow takes longer time to complete does not
give you any more time _prior_ to launch, does it?
Christian 8-)
Bill Daniels
"Bert Willing" <wil...@ir-microsystems.take-this-bit-out.com> wrote in
message news:3f9d3a52$1...@epflnews.epfl.ch...
> A winch driver won't get killed if the winch is equipped properly. And a
> cable breaking near the winch under full power is something very, very
> dangerous, so sitting on a winch without shielding is asking to be killed.
>
> The min team for winch launches is the pilot, the winch driver and the
wing
> runner (the winch driver can retrieve the cables on his own if the winch
has
> properly working brakes on the drums). If pilot and winch driver are
> suffiencently experienced, a chair may well replace the wingrunner
(although
> stating that in public may not be politically correct :-)
>
> During winch launch, any accident is related to pilot errors so you can
> basically keep the accident rate fairly low.
>
> On aerotows you may have situations were a cable break *will* induce an
> accident, and the pilot may just be able to influence the damage.
>
> --
> Bert Willing
>
> ASW20 "TW"
>
I was recently shown (very discretely) a wing runner replacement by a pilot
who uses ground launch.
I was comprised of a long tripod made of PVC pipe, topped with an inverted,
felt lined, ski-type runner, on which the wing tip slid. It would hold the
wings level for the first 2 meters of the takeoff roll. It could be
dismantled and stored in the glider trailer.
The successful use of this device depended on excellent radio communication
between the glider pilot and the tow car/winch driver plus a very good wheel
brake on the glider so that the pilot could prevent being pulled off the
tripod as the slack was slowly pulled out. I was told that it worked very
well.
Way back in the 1960's a friend and I would trailer our gliders out to
remote dry lakes in the Mojave Desert. We would take turns auto-towing the
other into the air. The obvious problem is that the pilot driving the tow
car was left on the ground with his glider if the other found lift.
On one occasion, I caught a thermal and soared away leaving my friend on the
ground. I felt bad about leaving him on the ground but thought - but hey, I
have lift. Shortly afterward, my friend joined my thermal in his glider.
He had talked a curious passer by into driving the tow car.
We just started the launch with the wingtip on the ground. Ground launch
crews can be very small.
Bill Daniels
Robert Ehrlich
> ...
> Winch launching is more Labour intensive than aerotowing
> as you need a winch-driver, a cable retrieve driver,
> a competent and experienced person making the decisions
> and supervising and a wingrunner.
The cable retrieve driver may be the same person as the winch-driver,
since there is no need for a winch driver during cable retrieve.
I did it on some occasions, having my car near to the winch, this
allowed me using it to go to the ether end of the field, bring back
the retrieve tractor to the winch, pull the cables to the other end
and go back to the winch with my car. Of course waiting time is reduced
with 2 persons.
In the same way the competent and experienced person making the decisions
and supervising may be the same person as the wingrunner. BTW if you
really need a wingrunner, your winch is underpowered, a wing holder
would be the approriate term if power is adequate, i.e. the initial
acceleration is so (about 1g) that no human can follow it.
About the initial question : Safety of winch launch vrs. aero tow?
I remember some time ago, when somebody already rasided the subject
in this newsgroup, I checked the statistics in the BGA database and
was surprised that they were in contradiction with my owns feeling,
which was that winch launch is safer. But as somebody pointed for some
accidents in this database, athough the fly started by winch launch,
the accident is not related to this. This at end did not change my
mind as my conclusion was that the cause of higher accident rate
in winch launching was not due to higher intrinsic risk but rather
that people didn't keep the same level of risk prevention (i.e.
training, observing procedures, checking the hardware) in winch
launch compared to aerotow.
I always think that the intrinsic risks are lower in winch launch,
for some objective reasons. Winch launching is a stable situation,
I winch launched non-RC models as a teenager, and nothing went
wrong although I discovered that a to abrupt release could induce
phugoid oscillation that wont stop before the glider meets the ground.
Aerotow on the contrary is an unstable configuration which can only
be kept by active actions of the pilot(s). Another fact is that,
except in very special configurations like in the case Mark Navarre
described at Torrey Pines, which are not really appropriate for
winch launching, a failure (cable break or power loss) can always
be recovered by a landing on the field, while in case of aerotow,
a cable break at the critical point will neither allow a landing
straight ahead nor a back turn for downwind landing. As in this
case there is no other solution than landing ahead in what is available
after the field, no training is possible for this case, while training
is possible for all cases in winch launching.
As a very new instructor (5 hours of instruction time now) most of
my instruction time was winch launch training, since the club decided
that during this end of season the flyable but non soarable week-ends
will be devoted to winch launch training, both for pilots and new
winch drivers, in order to try to increase the use of the winch during
the next season. During this time I observed what I think is an
overreaction about safety. As most pilots got warning with a very
strong emphasis about the danger of a to high nose up attitude at
the beginning of the launch, they are reluctant to take the proper
climb attitude, which by the way may be perceived as very abnormal
for a pilot not familiar with it. I had to insist on the need of
doing it for efficicient launch and on the dangers of an insufficient
nose up attitude : excessive speed with risk of exceeding Vw, loss
of tension in the cable which may allow the parachute to open,
poor climb which doesn't ensure the proper proportion between altitude
and length of runway ahead, so that in case of launch failure, when
you no more have sufficient runway ahead, you have the height appropriate
to do an abbreviated pattern.
and decisions in case of launch failure.
Mike Borgelt
wrote:
>
>> >"Mike Borgelt" <mbor...@borgeltinstruments.com> wrote in message
>> >news:vfeopvosok0nr9vjl...@4ax.com...
>>
>> And for you guys who operate on nice green grass airfields which allow
>> things like cable retrieve winches - it don't happen in Oz.
>>
>***********
>You have obviously never been to the Long Mynd - I have heard it described
> rather unkindly) as " a barely levelled granite hilltop".
>
Actually I have in 1988.
The surface looked pretty good compared to most Oz airfields. There
are one or two which I've jokingly said you would fail an outlanding
check if you picked the airfield.
I'm sure there are good statistics available for the safety of winch
vs aerotow but nobody has come up with them.
Winching is cheaper for training but has anyone noticed that gliding
is shrinking worldwide? Perhaps the old way of doing business is no
longer successful?
I think we need to realise that gliding is a sport for *pilots*.
First turn a newcomer into a pilot.
There is a wonderful array of small light aircraft and /or
motorgliders available nowadays at very reasonable prices. In Oz a
Pipistrel Sinus costs about the same as a new ASK21 and for the
purposes the K21 would be mostly used for (primary training) the Sinus
might be not quite as good a sailplane but will more than adequately
do the job and lets you teach cross country navigation, outlanding
field selection etc as well as being a not bad two seat bugsmasher.
Combine training in one of these with motivational rides with cross
country pilots in high performance two seat gliders(minimum - Janus,
Duo etc preferably with self launch or turbo to prevent outlandings)
and I think you might have a 21st Century soaring movement that might
have a fighting chance of actually retaining the people that come to
it.
Mike Borgelt
Fred Blair
it happens often, especially if the student fails to call 200ft.
Fred
F.L. Whiteley
"E. A. Grens" <ea...@citlink.net> wrote in message
news:4B0nb.5758$DS5....@news02.roc.ny...
launched regularly I can count on one hand the number second snaps taken per
season to soar away. Of course, _big wings_ do help, but that's another
thread;^) This season, I only took two aerotows to 2000agl. My other AT
releases were 1200 to 1700agl, that is, at or below winch height and near
enough to the airfield to presume had we been winching, getting away was
pretty likely. For a number of reasons we didn't winch much this season,
but when we did, we soared. This included thermals on New Year's Day and
wave on Feb 1 and thermals each subsequent winch day this season. Looks
like snow for November 1st though. Last Saturday would have been perfect as
lift was 10kts to 12K in a stiff NW breeze. The kind of day we get 2500+agl
on the wire.
Frank Whiteley
F.L. Whiteley
"Stefan" <stefan@mus._INVALID_.ch> wrote in message
> Bill Daniels wrote:
>
> >> BTW, How about some of our British and European friends with lots of
> winch
> >
> > experience jumping in here?
>
>
> Winch launching has much more safety issues for the ground crew and
> spectators than for the pilot. Be sure to have an experienced person
> show you safe procedures.
>
> Of course, an experienced winch driver helps a lot, too. At our club, a
> new winch driver must do 50 launches under supervision befor he's
> allowed to winch alone. We never had a winch accident in 40 years.
>
> Stefan
>
simple
single-drummed affair.
Frank Whiteley
F.L. Whiteley
"F.L. Whiteley" <gre...@greeleynet.com> wrote in message
news:3f9de251$1$200$7586...@news.frii.net...
a winch hundreds or thousands of times and still not have seen it all, and
hopefully, never will.
Frank Whiteley
Marry Daniel or David Grah
guess I got the basics down during a visit to New Zealand. In any event my
experience at the place was more positive as was the success of all of the
launches than your experience. "Lights on!" and all. I liked the rustic
feel of things, felt clear on and comfortable with the safety measures and
procedures in use, and my license no longer says aero tow only.
David Grah
Bishop, California
Bert Willing
different days.
--
Bert Willing
ASW20 "TW"
"F.L. Whiteley" <gre...@greeleynet.com> a écrit dans le message de
news:3f9de2fb$0$194$7586...@news.frii.net...
Eggert Ehmke
> BTW, How about some of our British and European friends with lots of winch
> experience jumping in here?
I have done some 1500 winch launches and about 50 aerotows. Beside some
cable breaks, I can't remember any uncomfortable situation during a winch
launch. I can't tell this of the aerotows.
In Germany, winch drivers have to do at least 100 launches on 10 different
days under supervision of an experienced driver. The 10 days rule is to
ensure different weather/wind situations during the training. We expect
every pilot to get his winch driver licence. The driver will get a
replacement after some hours and normally can choose his favorite glider
after his shift.
As for unexperienced winch drivers: anything that can happen (cable breaks,
engine problems, other launch interruptions) can be and must be handled by
the pilot.
On our 1200 m strip, we normally get 350-600 m after release. On good
thermal days, this is pretty enough to get away. With students we can do
easily lots of patterns of 6-10 minutes.
Eggert
Bob Johnson
Your ability to get 600 m releases with a winch on a 1200 m strip seems
extraordinary. Is your cable length just 1200 m also or is it greater
than your strip length?
Thanks for your input.
BJ
Bill Gribble
>Your ability to get 600 m releases with a winch on a 1200 m strip seems
>extraordinary. Is your cable length just 1200 m also or is it greater
>than your strip length?
350-600m is between 1155' and 1980' (approximately)?
Our own main strip is 1500m. In my somewhat limited experience, the
typical winch launch releases a K13 at 1600'. With an appropriate
head-wind, I've read that launches of up to 3000' (910m ?) can be
achieved from this particular strip (though possibly not in a K13!),
though that could well be just innocent boasting.
In that context, is 600m from a 1200m strip quite so extraordinary?
Especially as it was cited as the outside boundary of a range (ie. 350
to 600).
From a complete layman's point of view (well, one with 12 winch launches
so far and 1 aerotow to his name) I'd say that the winch was a good deal
more exhilarating than a tow and thus feels a damn sight more risky. But
I understand that if you fly the launch by the book then the winch is
perfectly safe.
That said, I've also read somewhere that the main contributors to
gliding fatalities in the UK are mainly mid-airs and "spin-ins" from
steeply initiated winch launches.
If that's the case, then perhaps the fact that a pilot launching on
winch only has himself to worry about, as opposed to one on tow who also
has the tug pilot's safety as a concern and responsibility, might leave
the former more predisposed to taking chances with his personal safety?
And perhaps the fact that you do need to fly a winch launch aggressively
(by comparison) if you want to make the maximum possible height out of
it, whereas with a tow, failing pilot error, mechanical failure or other
eventuality, you are going to make the release height you want
regardless. A winch has a 30 second window at best. A tow can take as
long as it needs within reason.
Of course, none of this contributes the stats and figures requested. And
all of this could be attributed to the flawed mis-interpretations of a
complete newbie who has read far too much in the last three months to
possibly retain any of it with a reasonable degree of accuracy ...
--
Bill Gribble
/----------------------------------\
| http://www.cotswoldgliding.co.uk |
| http://members.aol.com/annsweb |
| http://www.shatteredkingdoms.org |
\----------------------------------/
Stefan
> Your ability to get 600 m releases with a winch on a 1200 m strip seems
> extraordinary.
It all depends on the wind. With zero wind, the rule of thumb is that
you get approximately 1/3 the cable lengh. More with headwind, much more
with strong headwind. With extraordirarily strong headwind, you can even
kite. (Yes, it has been done.)
Stefan
Bill Gribble
> With extraordirarily strong headwind, you can even kite. (Yes, it has
>been done.)
Whilst I have no trouble believing that, it does conjure up some curious
mental images ... Though perhaps that speaks more of my own mental
imbalance than that of the suggestion <g>
Eggert Ehmke
> Mr. Ehmke --
>
> Your ability to get 600 m releases with a winch on a 1200 m strip seems
> extraordinary. Is your cable length just 1200 m also or is it greater
> than your strip length?
That's 1200 m of cable laid out, with a V8 240 HP engine at the other end.
What I told is the normal range - with strong wind aligned to the runway we
had 750 m (2460 feet) agl with a double seated ASK21. I did not see this
launch, but it sounds reasonable. 650 m I have experienced myself.
Eggert
Gary Boggs
for a new twist, one of our members has built a "pay out winch". A pay out
winch is a drum with a break on it. The glider hooks up about 200' behind
the tow vehicle, and as the glider climbs, the line spools out. Does
anybody have any experience with this type of launch? How much runway do
you need for this type of launch, how high can you get, ect?
Boggs
"Stefan" <stefan@mus._INVALID_.ch> wrote in message
news:3f9e955d$1...@news.swissonline.ch...
Mike Borgelt
<gary....@charter.net> wrote:
>I really appreciate all this good input, thank you all for responding. Now
>for a new twist, one of our members has built a "pay out winch". A pay out
>winch is a drum with a break on it. The glider hooks up about 200' behind
>the tow vehicle, and as the glider climbs, the line spools out. Does
>anybody have any experience with this type of launch? How much runway do
>you need for this type of launch, how high can you get, ect?
>
>Boggs
Don't know about that one but car tows generally aren't as good as a
winch as the initial accleration is much slower. You are accelerating
the car as well as the glider. The winch motor only accelerates the
glider and wire.
The car doesn't last very long in that sort of duty either.
Mike Borgelt
John Galloway
John Galloway
Bill Daniels
"Gary Boggs" <gary....@charter.net> wrote in message
news:vptd5vi...@corp.supernews.com...
> I really appreciate all this good input, thank you all for responding.
Now
> for a new twist, one of our members has built a "pay out winch". A pay
out
> winch is a drum with a break on it. The glider hooks up about 200' behind
> the tow vehicle, and as the glider climbs, the line spools out. Does
> anybody have any experience with this type of launch? How much runway do
> you need for this type of launch, how high can you get, ect?
>
> Boggs
>
I've done lots of auto tows and winch launches but no payout winch launches.
But, I have done some back of the envelope calculating for payout winches.
Payout winches seem to work fine for hang gliders where the towing speeds
are far lower than sailplanes. The speeds needed for sailplanes really jack
up the numbers.
Assuming no wind, (Given enough wind, anything works - even a large stake.)
the tow car has to accelerate to the normal towing speed plus the payout
rate. The normal glider airspeed at the beginning of the climb will be
about 55 - 60 Knots. Correcting this for True Airspeed, depending on
density altitude, may be 70 - 75 MPH on the tow car speedometer. To pay out
enough wire to make the effort worthwhile, (Say, 2500 feet in 60 seconds)
the payout rate will be about 45FPS or 30MPH which brings the tow car speed
to 105MPH - a bit fast for my taste. Now the tow car speed will decrease as
the glider climbs so the distance required will be less than that covered at
100MPH for one minute. But you have to add in the distance to accelerate
and stop the tow car.
Juggle the numbers for yourself but it looks like you will need a 12,000
foot runway and really fast car - or lots of headwind. Consider also that a
heavy two-seater will demand nearly 250 HP at the tow hook and a wire
tension of about 1300 pounds. Your tow car had better be heavy as well as
fast.
This starts to make a standard winch launch look good.
Bill Daniels
Bob Mowry
How about this one:
100% of 2003 US glider fatalities occur after aerotow.
Sounds like a good tag line for a winch manufacturer advertisement :)
-bob
Adrian Jansen
wind on the ground, and someone suggested we try a launch. An instructor
and I climbed into a Blanick L13, launched ( *very* short run ! ) and
climbed to 4300 ft still on the wire. Of course we needed the expert
cooperation of the winch driver, who eased off the power as we got about 500
ft, then payed out cable to let us climb. At the end, it was mostly the
weight of cable ( single strand high tensile steel wire ) which determined
the max height, although there wasnt much wire left on the drum.
--
Regards,
Adrian Jansen
J & K MicroSystems
Microcomputer solutions for industrial control
"Stefan" <stefan@mus._INVALID_.ch> wrote in message
news:3f9e955d$1...@news.swissonline.ch...
Eric Greenwell
@hotmail.com says...
Unfortunately, not true: some have occurred after self-launch, and I
know there have been some ground launch fatalities (how recently, I
can't remember)
--
!Replace DECIMAL.POINT in my e-mail address with just a . to reply
directly
Eric Greenwell
Richland, WA (USA)
Bob Johnson
Those are really good numbers for your winch.
With V8 300 HP (GMC 454 c.i., 7.4 L), and 5000 ft (1550 m) Plasma line
laid out, we are getting the rule of thumb 1/3 cable length releases of
1700 ft (525 m). This is into 10-15 kt wind. Much over that, we leave
the Blanik in the barn!
BJ
Midland, Texas
Tim Ward
Now
> for a new twist, one of our members has built a "pay out winch". A pay
out
> winch is a drum with a break on it. The glider hooks up about 200' behind
> the tow vehicle, and as the glider climbs, the line spools out. Does
> anybody have any experience with this type of launch? How much runway do
> you need for this type of launch, how high can you get, ect?
>
> Boggs
I have quite a bit -- in hang gliders. It works best with lots of road,
runway, or dry lake.
We typically got about 2/3 of the paid-out line in altitude. With 6000 feet
of 3/16 inch polyprop, we could get 4000 feet.
More typically, we'd tow until we hit a thermal somewhere above 500 feet.
If you don't have a dry lake handy, you can "step tow". The tow car stops
at the end of the road, and turns around (either a U turn or a "Y" turn), as
the glider also turns around, being careful not to wrap the rope around the
wing.
When the glider is more-or-less turned around, the tow car starts again.
Rinse, lather, repeat. The downwind run takes much less time.
This might not work in sailplanes. In hang gliders, we were using a
three-ring release, which doesn't back-release.
Tim Ward
Shirley
>How about this one:
>100% of 2003 US glider fatalities occur
>after aerotow.
Occur *after* aerotow? or *as a direct result of* aerotow?
soarski
I Think Gary had a similar question or topic here, a year ago or
longer.
Seems to me, he likes winches, but his club has doubts.
I was trained with winch launches to solo in Germany, after I had
already learnt to fly airplanes in the US. Subsequently I got into
soaring in CO with aerotow, the going thing. Visiting Germany through
the years, I realize how much more experience there is about that
method. There are many places, where there is winch launch only! There
are pilots with two years experience of flying who have never seen an
aero tow!
One canot make any comparison or have statistics! It all depends who
does it, and his knowledge. When I look at modern winches and
everything that goes with it, winch launching is really quite
complicated and specialized.
Take a good Towplane, a good instructor, a talented pilot, and in no
time one has a towing operation going. In the US, to start a winch
operation, which is as perfect as Oerlinghausen or similar would take
a lot. To my knowledge, there is not a decent winch in the US, by
comparison to Germany and what they have.
Bill Daniels knows his stuff, but I think he is the exeption in the
US.
As for Gary Boggs, the only thing I can suggest is to go to Germany
for a summer and learn the trade. Winches, how to run them, including
the infrastructure. (Telephone)
On the other hand, with more reasonable selflaunchers coming out, the
winch effort may not be the answer anymore in the US. There are enough
reasons mentioned in this thread.
Happy Halloween
Christian Husvik
> I really appreciate all this good input, thank you all for responding. Now
> for a new twist, one of our members has built a "pay out winch".
Haven't heard about that, but I _have_ heard about a hairy thing called
"step towing", which is something the hang-glider pilots do from small
fields. They winch up to say 150m, have the winch pay out as the fly
back, turn and take another winch launch from altitude! This can of
course be repeated for as many times as practical, and some respectable
altitudes can be gained.
Imagine this done with a glider and dyneema or spectra cord for wire.
You would of course have to modify the tow-hook to not automatically
back-release (shudder, gulp!)...
Well, if someone actually tries this with a sailplane I'm not sure I'd
want to know. They would certainly not be allowed to fly _my_ glider
anyway.
Christian 8-)
Slingsby
> If it's soarable, one launch should do most days. Most seasons I winch
> launched regularly I can count on one hand the number second snaps taken per
> season to soar away. Of course, _big wings_ do help, but that's another
> thread;^) This season, I only took two aerotows to 2000agl. My other AT
> releases were 1200 to 1700agl, that is, at or below winch height and near
> enough to the airfield to presume had we been winching, getting away was
> pretty likely. For a number of reasons we didn't winch much this season,
> but when we did, we soared. This included thermals on New Year's Day and
> wave on Feb 1 and thermals each subsequent winch day this season. Looks
> like snow for November 1st though. Last Saturday would have been perfect as
> lift was 10kts to 12K in a stiff NW breeze. The kind of day we get 2500+agl
> on the wire.
>
> Frank Whiteley
**********************************************************************************
You guys should get a really good winch and pay someone to operate it
during the week. During the summer you could become a vacation
destination. Since there are nonstop flights from Europe to Denver
every day, you could probably get enough Brits and others to pay for
your winch and some rental gliders in a few summers.
F.L. Whiteley
"Eric Greenwell" <flyg...@charterDECIMAL.POINTnet> wrote in message
news:MPG.1a08cda2a...@news.charter.net...
The following occured in the launch phase
Two fatals I'm aware of. A homebuilt failed structurally in a winch launch
in Colorado some years ago and apparently another homebuilt crashed in North
Carolina in the past couple of weeks on auto tow. Not clear whether the NC
accident pilot was even trained in ground launch. Perhaps someone in that
neck of the woods can offer more information.
A Russia was damaged in Wyoming a few years back on auto tow at a private
ranch strip, however, the grapevine reported the pilot had no specific
ground launch training and cart-wheeled the glider. IIRC, it was properly
repaired and sold.
A sometimes RAS poster was seriously injured in a winch launch accident
involving a Phoebus C in Georgia a few years ago. (stalled all-flying tail
to excessive pitch-up to wing stall, wing-drop, and rolled inverted to
impact)
Any others? Certainly there have been a few at Torrey Pines over the
decades, though environmental factors have been a big player there.
Frank Whiteley
F.L. Whiteley
least one major auto maker produced a limited production launch vehicle
pick-up truck as advertised on national TV. Others were retro-fits or home
grown. The current generation of US UL gliders, Sparrowhawk and Lighthawk,
could probably use these as supplied. The Apis and Silent might need
something a bit more stout.
Frank Whiteley
"Gary Boggs" <gary....@charter.net> wrote in message
news:vptd5vi...@corp.supernews.com...
Robert Ehrlich
1/3 cable length seems low. There was in France an experiment showing
40% cable length without wind with cable length from 1000 to 2000 m.
See HTTP://www.gliderforum.com/thread-view.asp?threadid=385&MessageID=1466#1466
Robert Ehrlich
> ...
> As for Gary Boggs, the only thing I can suggest is to go to Germany
> for a summer and learn the trade. Winches, how to run them, including
> the infrastructure. (Telephone)
>
Why telephone rather than radio? Radio let everybody know what is
happening, rather than only the two persons at bot end of telephone.
Likely mandatory when there is some other activity in parallel (aero
tow, power flying ...).
> On the other hand, with more reasonable selflaunchers coming out, the
> winch effort may not be the answer anymore in the US. There are enough
> reasons mentioned in this thread.
>
What does "reasonable" mean here? Selflaunchers are a way to increase
the cost of flying, winch is a way to decrease it.
Bob Johnson
I would like to learn how they do this. Our Blanik has perhaps the best
located CG hook on any sailplane I'm aware of, although some would say
the bridle is somewhat awkward to use.
On a typical tow, with the Blanik weighing about 1100 lb, the 300 hp
winch engine throttle is advanced to the forward stop in 3 seconds and
at this time the engine is already rapidly approaching redline 5000 RPM.
At this point the Blanik is already beginning its climb and the throttle
is eased.
This quick takeoff and climb performance is still not fast enough to
load the ship and its occupants to more than about 0.8 - 0.9 G
horizontal acceleration, which I think one would have do to attain any
more than the 1/3 line length releases we are attaining.
We limit our climb airspeed to 55-60 kt, which I believe is the POH
recommendation. Very little if any back stick is necessary, and the
Blanik attains the 55 kt climb pretty much on its own until the last
part of the 45 second tow, when some back stick is applied to counter
the downward (with respect to the ground) pull of the rope. Our
Spectra/Dyneema/Plasma plastic rope weighs less than its full 66 lb when
partially wound on the drum, so line weight (and its necessary
acceleration and ground contact friction) for us is practically
negligible.
If there is a better setup anywhere in the world, I would sure
appreciate a description.
Thanks for your reply,
BJ
Midland, Texas
http://www.permiansoaring.us/
Marcel Duenner
> On Sat, 25 Oct 2003 12:43:35 -0700, "Gary Boggs"
> <gary....@charter.net> wrote:
>
> >Someone must have already compared the safety of these tow launch methods.
> >What do the statistics show is the safer method of launch? Aero tow seems
> >to involve more inherent dangers to me. For one thing, there is just more
> >time for things to go wrong. What could be more dangerous than to tie tow
> >airplanes together and try to fly?
> >
> >Gary Boggs
> >
>
> I've only done about two winch launches but have done several hundred
> car tows and driven several hundred also.
Two winch launches. Helps to understand why you say what you say later
on.
>
> Ground launches involve lots of wire, rope etc. It is probably a good
> observation that the more rope you have the more trouble you can get
> into! With one exception below.
>
> I've had the glider run over the wire and tangle in the wheel well.
> Not good as you now cannot release and depend on the tow driver..
>
> Pilot reactions to a low altitude winch launch failure are utterly
> critical. I suspect we've killed dozens if not hundreds over the years
> this way around the world.
Yes, the reaction is critical. But even more important is the correct
attitude corresponding to airspeed and altitude at all times. This
does make the reaction when something goes wrong a quite a bit less
critical.
I guess we have about 0.5 cable breaks and 2 or 3 weak link breaks per
1000 launches. We do about 3500 winch launches a year. It can happen
and if the pilot is properly instructed he knows this and is prepared.
I do not consider cable break or engine failure to be a _problem_ when
launching even when it happens.
>
> You may need more than one launch to get away(rare with aerotow).
Normally not.
> Someone mentioned the stresses in the wire and the glider. Both are
> much lower in properly executed arotow.
Stresses are normally higher, but where's the problem in that? The
glider is built to easily take those stresses and we change the wire
once a year anyway.
>
> Aero tow may have a higher exposure to an off airport landing in
> unsuitable terrain but the failures seem to be much more rare than
> winch wire breaks. If you don't use toy towplanes(less than 180HP)
> then any place suitable for winching probably gives you the
> opportunity to do a 180 or land straight ahead from an aerotow.
Definite 'No' on the 'probably gives you' bit.
From a winch launch you should _always_ be able to land on the
runwyay. I know lots of airfields where you have a certain time,
sometimes only two or three seconds, sometimes ages, in the aero tow
when you definitely do _not_ want _anything_ to go wrong. The
suitability of the airfield for whinch launching has no relevance
here.
>
> If you want gliding to be popular aerotow involves less running around
> on the ground per flight hour.
Don't see why. Only thing to do additionally is retrieveing the winch
cable. And the guy drives, he doesn't run.
And: If you want gliding to be more popular among the people living
near the airfield you should stop making such a racket with those
ancient technology fuel to noise converters. Instead we do 80% of our
launches with 0.4 litres of Diesel.
>
> Flying towplanes is more fun than driving a winch or tow
> car.(Allegedly - I last sat in a towplane in 1971 writing down CHT's
> for the cooling test for 4 tows in a row and haven't felt motivated to
> get into a towplane since despite the aquisition of a PPL 9 years ago)
>
> Aerotowing danger can be reduced by using a longer rope. One of the
> local clubs around here tried it and liked it so much the towpilots
> won't fly with short ropes. The long rope gives everyone more time to
> handle upsets. I suspect the rise of the towplane upset accident
> coincided with using shorter ropes.
Agree to all that.
Regards
Marcel
Andreas Maurer
<Robert....@inria.fr> wrote:
>Why telephone rather than radio? Radio let everybody know what is
>happening, rather than only the two persons at bot end of telephone.
>Likely mandatory when there is some other activity in parallel (aero
>tow, power flying ...).
Nothing worse than someone else interfering during the critical phase
of a winch launch (initial acceleration).
Bye
Andreas
Eggert Ehmke
> I would like to learn how they do this. Our Blanik has perhaps the best
> located CG hook on any sailplane I'm aware of, although some would say
> the bridle is somewhat awkward to use.
> On a typical tow, with the Blanik weighing about 1100 lb, the 300 hp
> winch engine throttle is advanced to the forward stop in 3 seconds and
> at this time the engine is already rapidly approaching redline 5000 RPM.
> At this point the Blanik is already beginning its climb and the throttle
> is eased.
As a winch driver, I allways try to leave the throttle in the position it
has when the plane leaves the ground, for about the first 1/3 of the climb.
Then I slightly slow down, depending on the wind and the climb angle of the
plane. This can mean full throttle for a double seater and almost idle for
a Ka8 with strong headwind. This method works in all wind conditions.
With an ASK21 or Grob G103, the ground roll is not longer than 2 or 3
seconds. The first ca. 100 feet we keep a flat attitude, than we go
slightly into a climb angle of about 40 degrees.
> We limit our climb airspeed to 55-60 kt, which I believe is the POH
> recommendation.
This seems a bit slow for me, but may be correct for the Blanik. The ASK21
has a recommended speed of about 60 kt, and 65 is no problem. More speed
means more lift too.
> Very little if any back stick is necessary, and the
> Blanik attains the 55 kt climb pretty much on its own until the last
> part of the 45 second tow, when some back stick is applied to counter
> the downward (with respect to the ground) pull of the rope.
In the last part of the climb it is even important to give the stick a
little forward, so the angle between cable and plane does not exceed the
point where the backrelease is triggered. That way you can stay longer on
the rope, getting higher. Also the release is much softer.
Just my 2 cents...
Eggert
Robert Ehrlich
>
> Robert --
>
> I would like to learn how they do this.
The experiment I was talking about was done in another club,
so I have no direct information about it. However, when our winch
correctly delivers its power, we also get about 40% of cable length,
i.e. 400m with 1000m cable.
> Our Blanik has perhaps the best
> located CG hook on any sailplane I'm aware of, although some would say
> the bridle is somewhat awkward to use.
> On a typical tow, with the Blanik weighing about 1100 lb, the 300 hp
> winch engine throttle is advanced to the forward stop in 3 seconds and
> at this time the engine is already rapidly approaching redline 5000 RPM.
> At this point the Blanik is already beginning its climb and the throttle
> is eased.
There are some differences with what happens in my club: the reduction
ratio is not the same by us, engine RPM is 1800-2000. We never get
near redline, although the throttle is kept to the forward stop for
2 seaters (ASK21) until the glider seen from the winch crosses the
angle between the front window and the top window, i.e. cable angle
near 45 degrees. Our engine has only 200 hp.
>
> This quick takeoff and climb performance is still not fast enough to
> load the ship and its occupants to more than about 0.8 - 0.9 G
> horizontal acceleration, which I think one would have do to attain any
> more than the 1/3 line length releases we are attaining.
>
> We limit our climb airspeed to 55-60 kt, which I believe is the POH
> recommendation. Very little if any back stick is necessary, and the
> Blanik attains the 55 kt climb pretty much on its own until the last
> part of the 45 second tow, when some back stick is applied to counter
> the downward (with respect to the ground) pull of the rope. Our
> Spectra/Dyneema/Plasma plastic rope weighs less than its full 66 lb when
> partially wound on the drum, so line weight (and its necessary
> acceleration and ground contact friction) for us is practically
> negligible.
>
> If there is a better setup anywhere in the world, I would sure
> appreciate a description.
>
Maybe a reduction ratio on the engine allowing full throttle without
crossing redline, keeping full throtte longer during the climb, climbing
at 60 kt rather than 55 kt. And probably a higher nose up attitude during
the first part of the climb, which would be allowed with more power and
speed during this phase. But maybe the difference is only due to the
better aerodynamic of the ASK21 compared to the Blanik. I don't remember what gliders
were used in the experiment I reported about, but probably modern
gliders, certainly not Blaniks (almost unknown in France).
> Thanks for your reply,
>
Martin Gregorie
True enough, and you wouldn't want the continuous stream of "take up
slack....take up slack....all out...all out" occupying a common-use
channel either. We use radio to control launch but its on a dedicated
channel (sorry - I don't know the frequency) that is separate from our
tugging frequency and is one that I've never heard interference on.
One benefit is that as well as the winch, the cable truck, golf
buggy[1] and office are all on the channel so the launch marshal can
talk to anybody he needs to.
[1] an excellent and economical way of moving gliders about.
--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :
JJ Sinclair
>Any others? Certainly there have been a few at Torrey Pines over the
>decades, though environmental factors have been a big player there.
>
>Frank Whiteley
Its been a long time now, but a group was auto-towing a Cherokee at Air
Sailing, NV. The initial flights were made with a pulley attached to a stake in
the ground and car driver heading straight for the glider. After several
flights they decided to put the pilley on the car and NOBODY knew that would
DOUBLE the glider speed. The driver "Stood on it " hard and finally obtained
his briefed 50 mph. The glider was now doing 100 and pilot was unable to
release due to excessive tow line pressure. The wings came off and pilot was
killed.
About 20 years back, a group was auto-towing a Monarch at Kingdon, Ca. That
went so well, they decided to hook it up to a tow plane. The ship did several
PIO's as the pilot tried in vain, to release. He survived, but doesen't
remember anything after the 3rd grade.
My pilot licence still reads, "Aero-Tow- Only"
JJ Sinclair
Robert Ehrlich
>
> On Wed, 29 Oct 2003 10:02:06 +0000, Robert Ehrlich
> <Robert....@inria.fr> wrote:
>
> >Why telephone rather than radio? Radio let everybody know what is
> >Likely mandatory when there is some other activity in parallel (aero
> >tow, power flying ...).
>
> Nothing worse than someone else interfering during the critical phase
> of a winch launch (initial acceleration).
>
A worse thing would be someone interfering not to the communication but
to the launch itself because he is not aware of the launch. Of course
this is a discipline that everybody has to observe, i.e. don't use
the radio for anything else when a winch launch is in progress. This
also implies that every glider or tow plane has a working radio, which
is the case by us.
Bill Daniels
"Bob Johnson" <robj...@cox.net> wrote in message
news:3F9F310D...@cox.net...
> Eggert --
>
> Those are really good numbers for your winch.
>
> With V8 300 HP (GMC 454 c.i., 7.4 L), and 5000 ft (1550 m) Plasma line
> laid out, we are getting the rule of thumb 1/3 cable length releases of
> 1700 ft (525 m). This is into 10-15 kt wind. Much over that, we leave
> the Blanik in the barn!
>
> BJ
> Midland, Texas
Bob, When winching, the wind is your friend. Quitting at 15 knots is not
necessary. I have winched into 35 knots and higher winds and the results
are spectacular. Each 10 knots of headwind is the equivalent of about 40
additional HP.
The thing that often severely limits the altitude gained is a slow pitch-up
profile at the start of the launch. The final height achieved is largely
determined by the profile flown in the first few seconds of the launch.
Now, as everyone has pointed out, you need to be careful here. Safety at
the start of the climb is a combination of airspeed, altitude and attitude.
The more you have of the first, the faster you can get the second two and
the higher you will get.
I've done calculations, simulator runs (X-Plane) and flight test to prove
the following point. If you have 60 knots in a glider with a stalling
airspeed of 40 knots, you can be in full climb attitude at zero altitude and
still have a large safety margin. Practice this way - at several thousand
feet AGL, zoom the glider into a 50 degree nose-up attitude. As the
airspeed decays to 60 knots, yell "WIRE BREAK", delay 0.5 seconds
(simulating reaction time) and pitch forward at zero G. Watch the airspeed
and altitude, you'll see what I mean. (For winch CFI-G's, this is a great
way to teach how to handle wire breaks.)
If you have (or simulate) a wire break at this point and start a zero G
pitch over after a .5 second delay, the minimum airspeed during the
parabolic ballistic trajectory will be about 50 - 55 knots when the glider
reaches apogee at an altitude of about 100 feet AGL. So there you are at
100 feet and 55 knots in a normal gliding attitude - not exactly a
problematic situation, just land straight ahead. The reason this works is
that the glider's induced drag at zero G is minimal so the airspeed decay is
mainly just due to gravity and the glider follows a parabolic trajectory
until the pilot re-establishes one G at the normal glide attitude.
I need to repeat that I am not advocating a rocket blast-off kind of climb
profile but a smooth transition into the full climb without undue delay
equipped with a full understanding of the safety margins.
Bill Daniels
Bert Willing
driver. Did that for 10 years in Germany, happy to do it by radio ever since
I left Germany, hadn't had an interference from others on the same
frequencies for the last 13 years :-)
--
Bert Willing
ASW20 "TW"
"Andreas Maurer" <alph...@t-online.de> a écrit dans le message de
news:b8hvpvobj4gn4v7sf...@4ax.com...
Bill Daniels
"JJ Sinclair" <jjgl...@aol.com> wrote in message
news:20031029100352...@mb-m14.aol.com...
JJ, you've had some bad experiences and I'm sorry for that. But you have to
realize that there are hundreds of thousands, if not millions of winch
launches all around the world that go off without a hitch simply because the
people involved know what they are doing.
If we take the trouble to learn from them and not try to re-invent the
wheel, ground launch becomes very safe and enjoyable. (The first thing to
learn is not to use a Schweitzer-type tow release for anything at all,
period.)
Bill Daniels
Tjeerd Mulder
steel cable. Works fine and very direct :-)
And in germany communication between winch and start point on air band radio
(only) is not allowed, you may use a radio on some other frequency.
Tjeerd
"Bert Willing" <wil...@ir-microsystems.take-this-bit-out.com> schrieb im
Newsbeitrag news:3f9fe158$1...@epflnews.epfl.ch...
Bob Johnson
You are exactly right with those finer points of flying the launch.
Thanks for adding those to the thread.
Also we will want to try maybe 60-65 kt in the climb next time we go
out.
Cheers,
BJ
Bob Johnson
Those are all good points, see my reply to Eggert.
Our engine is petrol fueled. Despite Google's best efforts, I have not
yet located a Torque/HP/RPM curve for our very common 7.4 L engine, but
have heard that it develops max torque and HP at about 3000 RPM and
further that the curves are fairly flat at this point.
Our drum speed is around 400 RPM for about a 7-8/1 overall reduction
using first gear of our automatic tranny. We have lately begun bringing
in the parachute in second gear, which reduces engine wear and tear
considerably.
In addition to raising the unflapped climb speed to 65 kt, we also have
the option on our Blanik L-13 model to let out the Fowler flaps and
climb at a reduced airspeed. We have not yet tried the flaps during tow
to my knowledge.
You may be using a Diesel, which could account for your good performance
at lower revs.
Thanks,
BJ
Bob Johnson
I 'member my O-Nine Two oil field piano wire breaking at the half way
point during a tow in Roy Schlemeyer's old SGS 2-22. I yelled "Oh, line
break" or something to that effect and recall the glider innards debris
collected since the last ice age floating up and dancing before my eyes
as I dumped the stick full forward. Was it half a second before I
reacted? Can't believe I waited that long. And when the astronauts tell
you that zero-g is exhilarating, believe it.
Luckily, I had been well briefed by Roy as to what to expect. It has
been theorized that some people are "allergic" to zero-g and they
instinctively jerk the stick full back instead of push full forward.
Unfortunately, this is the last mistake they ever make and we can no
longer interview them as to why they did this.
There, we're back to the original question, "Is winch launch safer than
aerotow?" The answer? -- scroll down
IT DEPENDS!
Thanks and good to hear from you again.
BJ
Bob Kuykendall
> Its been a long time now, but a group was
> auto-towing a Cherokee at Air Sailing, NV...
I'm not sure, but I believe that was actually a Don Mitchell design
called the Nimbus III-B (no relation to the later Schempp-Hirth
product of similar name). That was in 1973:
http://www.ntsb.gov/NTSB/brief.asp?ev_id=85473&key=0
Thanks, and best regards to all
Marcel Duenner
> Nothing worse than an additional communication step between pilot and winch
> driver. Did that for 10 years in Germany, happy to do it by radio ever since
> I left Germany, hadn't had an interference from others on the same
> frequencies for the last 13 years :-)
>
Agree, the way they often do it in Germany is useless. Glider having
to tell the guy at the phone what he's supposed to then tell the
winch. It's so simple if the winch has a radio.
Our winch has had a radio for decades. Even when we used to give the
lauch signals with a flag! About fifteen years ago we switched to
telephone to give the launching commands but as soon as the glider has
left the ground the guy at the phone says _nothing_ more. Then only
the glider pilot says either 'faster' or 'slower' over the radio.
Since we have the wire tension indicated to the winch driver these
commands have become very rare and so have cable breaks.
Bob Johnson
go both ways, I 'member a time only a couple of years ago that I
experienced the dreaded aerotow line break at 200 ft and 60 kt over the
outbound fence.
I looked out front and it wasn't too exiting, so I gingerly turned
ninety to the left and the scenery looked some better, but not the
greatest, so I REALlY gingerly gave it another ninety to the left and
was really impressed this time as I found I was perfectly lined up with
the takeoff runway. And I recall I hadn't lost too much of my original
60 kt. Will wonders never cease!!
I thought "OK now God, you've made it possible for me to do this little
magic trick perfectly the first time I tried it in front of all my
friends and hangar bums, give me your hand again and let's try just one
more."
So I pulled spoilers, checked gear down and rolled up to my exact
takeoff spot.
And as I popped the canopy, my good friend who shall remain nameless,
said "S--t!, you've gone and lost us another Tost ring, somebody go back
to the hangar and see if they can find another tow rope". It was his
turn to tow, so I pushed back. Nobody else said a word.
Safety lecture from a dummy follows:
I don't remember to this day why I ninetied to the left. During the
previous year's biannual when Juan Batch pulled the plug on me over his
outbound fence, turning right was the correct choice because in that
direction lay the wind, which blows one back over the airport. This
improves the scenery like you wouldn't believe.
When I tried the trick for real solo, the wind lay to my left. I'd like
to think it was instinct. But I believe it was a coin toss.
Anyway, thank God. And Juan.
It Depends
BJ
JJ Sinclair
>JJ, you've had some bad experiences and I'm sorry for that. But you have to
>realize that there are hundreds of thousands, if not millions of winch
>launches all around the world that go off without a hitch simply because the
>people involved know what they are doing.
The subject under discussion is a club that is thinking about trying a new
launch system, winch launching and now pay-out winch. My point in posting on
this subject is to show what can happen when unskilled club members try a new
system.
JJ Sinclair
Bill Daniels
OK, JJ, If they are unskilled and insist on REMAINING unskilled, I'll give
you the point. Everybody starts out unskilled, however - I don't hold that
against them.
I don't think you are dissing ground launch, you're just warning that any
group needs to realize that there is a steep learning curve ahead of them.
I'll agree with that.
They've learned to fly gliders however, so they can't be dumb. I think they
can learn to operate a winch safely and enjoyably IF they take the trouble
to learn the art and science of it. There are lots of books to read and
this medium, the internet, connects us with the world where there is a
wealth of knowledge about ground launch.
If someone wanted to do the world of ground launch a great favor, they would
start a web site where the collective wisdom of the world could be displayed
so that anyone wishing to undertake winch launch could go there and get an
education.
Any volunteers?
Bill Daniels
I say learn and enjoy.
Bill Daniels
Andreas Maurer
<wil...@ir-microsystems.take-this-bit-out.com> wrote:
>Nothing worse than an additional communication step between pilot and winch
>driver. Did that for 10 years in Germany, happy to do it by radio ever since
>I left Germany, hadn't had an interference from others on the same
>frequencies for the last 13 years :-)
Don't forget that you rarely do 100 launches per day at your current
airfield with "Vent arriere" messages each 3 minutes, interfering with
launches... :)
(Yes - I'm envious!)
Of course you are correct - it's nice to have a direct connection
between pilot and winch driver.
My club at Landau has never had such a (radio) communication, and we
seldom miss it. Sometimes the Ka-8 gets too fast (and releases early),
but otherwise I cannot remember and disadvantages of not having a
glider-winch connection.
It's more a question of winch driver practice - drivers with little
practice tend to judge the speed wrong and need corrections.
To add some spice - I personally watched two bad winch accidents, each
had to do with power failure of the winch/too low airspeed. In both
cases there was direct radio communication between glider and winch.
Bye
Andreas
Bruce Hoult
Bob Johnson <b...@oneillpr.com> wrote:
> Our engine is petrol fueled. Despite Google's best efforts, I have not
> yet located a Torque/HP/RPM curve for our very common 7.4 L engine, but
> have heard that it develops max torque and HP at about 3000 RPM and
> further that the curves are fairly flat at this point.
You are making some totally contradictory and inconsistent claims there.
If max torque and max HP occur close together then they must both drop
off precipitously after that.
If the torque curve is flat then HP will be increasing linearly with
RPM, max torque and max HP will be very far apart.
It is quite likely that you do have maximum torque at around 3000 RPM,
but if for example the torque curve is flat enough that the torque at
the 5000 RPM redline is still 60% or more of that at 3000 RPM then that
(redline) is exactly where maximum power will be.
-- Bruce
Marcel Duenner
> had to do with power failure of the winch/too low airspeed. In both
> cases there was direct radio communication between glider and winch.
>
Of course having radio connection does not mean you can just let the
launch happen. You still have to fly it and react to whatever
situation arises. First, you have to use the radio. Second you have to
use it before it's to late and third and most important: never rely on
the use of radio of having any effect on the launch.
I still fail to understand why any winch or cabel failure should lead
to an accident. With or without radio. With or without wind. With or
without water ballast.
Be prepared.
Marcel
Robert Ehrlich
This raises the interesting question of the height loss during a 180 degrees
turn in a glider or an airplane with a dead engine. I recently had a dicsussion
about that with a friend who is a power pilot and on this occasion made again a
small computation I had already made on this matter. As I never have seen
these results elsewhere, I think it may useful to show that here. Assume
you fly your turn wit an angle of attack which correspond to the speed V
when flying straight and wings level, and that the vertical sink speed
in the same conditions wuold be Vz, then during this 180 degrees turn
flown with a bank angle phi, the height loss is pi*V*Vz/(g*sin(phi)*cos(phi)),
and the turn is flown at speed V/sqrt(cos(phi)). The optimum (minimal
height loss) is when sin(phi)*cos(phi) is maximum, i.e. phi = 45 degrees,
and the product V*Vz is minimum. A glance on a typical glider polar will
show that this last thing is obtained with V just below min sink speed, but
as it is not easy to find how many below, let's assume the turn is done
at min sink speed, this is not very far from the optimum. For a typical
glider with min sink of .6 m/s at 80 km/h (22.2 m/s) the height loss is
8.5 m, for a typical airplane with min sink of 3 m/s at 120 km/h (33.3 m/s)
the height loss is 64 m. This explains why the 180 degrees turn back to
the runway over the outbound fence succeeds in a glider but not in a power
plane.
In the case mentioned above, the speed (60kt) was far over the optimum,
however the result is as expected not catastrophic. Assuming a bank angle
of 45 degrees, the equivalent speed in straight flight would be multiplied
by 1.18, this gives 26 m/s or 93 km/h. Assuming the sink speed is 1 m/s in these
conditions, we get a height loss of 16.6m. This is for a poor glider (L/D =
26 at 93 km/h).
Martin Gregorie
Thanks for that. A most informative calculation and certainly matches
my most recent relevant experience.
The last time I was having a supervised aero-tow refresher in our
Puchacz I was doing a running commentary for the instructors benefit
and as soon as I said "400 ft - no problem now from a rope break" BANG
as he pulled the release. We had a touch over 60 kts and as soon as I
saw the rope go I pulled a 45 degree banked 180, keeping the 60 kts
just as Bob described, and was amazed at how easily we got in over the
fence. In fact, once I'd rolled out it looked like a normal approach,
so I opened the brakes and did a typical Puchacz approach and landing.
Brian Case
> start a web site where the collective wisdom of the world could be displayed
> so that anyone wishing to undertake winch launch could go there and get an
> education.
Ok it may not be the collective wisdom of the world. But there is
quite a bit of information on winch launching at:
http://www.northwestsoaring.com/sitemap.shtml
Let me know if I am missing anything really important about Winch
Launching here.
Brian Case
CFIIG/ASEL
Bill Daniels
"Brian Case" <bfc...@netzero.net> wrote in message
news:daf04928.03103...@posting.google.com...
Good site - congratulations.
About your 2003 procedures - you must have had a bad experience with gusty
wind conditions. This is why I have been advocating airspeed telemetry.
Bill Daniels
John Galloway
front seat of a Janus at Lasham with Derek Piggot in
the back during a cross country course. We were just
off the deck within the airfield waiting for the tug
to start to climb and I heard Derek say '60 knots'.
Later I asked him why he said that out loud and he
told me that he always made a note of when the speed
reached 60 knots because he reckoned that at that speed
he could pull up and turn back without loss of height.
John Galloway
At 14:00 30 October 2003, Martin Gregorie wrote:
>On Thu, 30 Oct 2003 10:11:18 +0000, Robert Ehrlich
Eric Greenwell
marca...@yahoo.co.uk says...
> I still fail to understand why any winch or cabel failure should lead
> to an accident. With or without radio. With or without wind. With or
> without water ballast.
> Be prepared.
I seem to recall some launches where the cable became tangled in the
main wheel, when the winch jerked the glider forward, then paused very
briefly. This is caused the glider to pitch up too fast at the start,
and the pilot was unable to release, leading to a crash. Perhaps this
is not what you mean by a winch failure?
--
!Replace DECIMAL.POINT in my e-mail address with just a . to reply
directly
Eric Greenwell
Richland, WA (USA)
Andreas Maurer
Duenner) wrote:
>I still fail to understand why any winch or cabel failure should lead
>to an accident. With or without radio. With or without wind. With or
>without water ballast.
>Be prepared.
100% agree.
I sometimes get the impression that in case of a glider-winch radio
connection the glider pilot tends to rely on his radio commands
("faster" - "slower") to correct a sub-optimum situation. Which
obviously not works in all cases and then might lead to an even worse
situation.
In case of no glider-winch connection the glider pilot completely
relies on himself and takes the according action if a certain
parameter (e-g. speed) exceeds the (his) limits.
Bye
Andreas
Chris Nicholas
to sheathe the cable with plastic hosepipe of suitable size at the
glider end, so it is too stiff to wrap round the axle (or even enter
the wheel box area). It is one of many things where the technology and
operational procedures have been modified and developed over the years
to reduce accidents and incidents to the minumum, leaving only pilot
error/failure to act as trained as the remiaining significant factor.
Chris N.
Eric G: "I seem to recall some launches where the cable became tangled
in the
main wheel, when the winch jerked the glider forward, then paused very
briefly. This is caused the glider to pitch up too fast at the start,
and the pilot was unable to release, leading to a crash. [snip]"
Bob Johnson
That's a very welcome correction to my hazily-remembered version of a
second-hand report of what the 454 c.i. engine torque/hp/rpm chart looks
like. This is the kind of info I was looking for and thanks for providing it!
In all our past kicking around of the ideal winch prime mover, here's one
that sounds silly but might rate at least an engineering investigation -- a
recip steam engine! If I recall correctly, the steam engine develops max
torque at stall.
What got me thinking about that was the fact that the Navy gets 66,000 lb
Super Hornets flying in about the same three seconds that it takes us to get
airborne. And they do it with steam, not because it's handy, but that's
probably the only practical way to get it done.
BJ
Martin Gregorie
<flyg...@charterDECIMAL.POINTnet> wrote:
>In article <23eed42b.03102...@posting.google.com>,
>marca...@yahoo.co.uk says...
>> I still fail to understand why any winch or cabel failure should lead
>> to an accident. With or without radio. With or without wind. With or
>> without water ballast.
>> Be prepared.
>
>I seem to recall some launches where the cable became tangled in the
>main wheel, when the winch jerked the glider forward, then paused very
>briefly. This is caused the glider to pitch up too fast at the start,
>and the pilot was unable to release, leading to a crash. Perhaps this
>is not what you mean by a winch failure?
That should be a recoverable situation provided that the signalling
channel between launch point and winch can convey three messages:
- take up slack
- all out
- STOP
If, as it appears to be the case at Torrey Pines, the headlamp signals
can't be used to signal STOP then you have an accident waiting to
happen. The launch marshal must ALWAYS be able to signal STOP and be
obeyed without question. Doesn't matter whether the channel is radio,
telephone, coded light flashes or signalling bat provided that it can
transmit those three commands unambiguously.
On the sites where I've winch launched an immediate STOP is signalled
if the glider overruns the cable for any reason. The reason we use the
three phrases listed above (repeated continuously) is that they have
three, two and one syllable and so can be distinguished despite noise
in the winch cab and/or wind noise in the launch marshall's
microphone.