Flight with disabled tail rotor
cla...@sj.znet.com
I understand under certain conditions if the tail rotor becomes
disabled, some helicopters can remain controlable enough to be able to
land.
On this newsgroup a long time ago I read about an instance where a
helicopter was deliberately flown successfully with the tail rotor
disabled.
Can someone please point me in a direction to learn more about
helicopter flight with the tail rotor disabled?
Thanks ahead,
Dan
Peter Seddon
rotor disappears then cut the engine and you may be able to autorotate
safely to the ground. This I beleieve is the only way you will fly without a
tail rotor.
Regards Peter
<cla...@sj.znet.com> wrote in message
news:3c00817f...@news.znet.com...
brien
flight "disappears" a loss of the weight of the tail rotor and gear box
that far aft from the aircraft would put the weight and balance out of any
hope of control flight.
Peter Seddon <pe...@seddonp.freeserve.co.uk> wrote in message
news:9tqn21$gqo$1...@newsg4.svr.pol.co.uk...
Peter Seddon
rotor if you like - but there again what does that mean ?!!
Regards Peter
"brien" <br...@whidbey.net> wrote in message
news:u023hj7...@corp.supernews.com...
Bart
Not all TR failures are the same, and each has its own procedure.
Stuck left, stuck right, neutral (pitch link loss), and loss of
components are the general categories.
In flight with reasonable airspeed most failures allow for continued flight. The
helicopter might yaw and roll a little, but it won't spin wildly. The fun part
is landing with this situation. Newton's action
and reaction law plays a big part in these landings. The TR is there to
counter the rotational forces of the main rotor torque. If you remove that
torque the helicopter will not spin wildly. The key to landing
with a TR failure is proper manipulation of airspeed, torque, and
altitude. The most severe and difficult is "loss of components", and
this will cause extreme CG problems and probably will not permit
continued flight. In this case, you chop throttle, autorotate,
and say a little prayer.
Many TR failures happen very near the ground as a result of
the pilot inadvertently sticking the TR into some obstacle. In this
case you just chop throttle and do a hovering autorotation.
Another leading cause of (civilian) TR failures is some foreign
object getting jammed in the mechanism (e.g. an unsecured flashlight
rolling under the bubble and getting wedged in the pedals).
The notion that helicopters will spin wildly of the sky with any
loss of TR is probably one of the biggest misconceptions held by
non helicopter pilots.
Bart
Badwater Bill
>"So if the tail rotor disappears" I would expect those parts falling off in
>flight "disappears" a loss of the weight of the tail rotor and gear box
>that far aft from the aircraft would put the weight and balance out of any
>hope of control flight.
Depends. You can have lost of tail rotor control and still have the
thing attached. I think the question is more to this nature. Some
ships fly okay if you have enough forward speed when you lose control
of the tailrotor. The machine simply weathervanes and stays straight.
On landing, you have to do a run-on unless you autorotate in. But
other than that, it can be fairly controllable.
Bill
Timothy Pruitt
remain controlable and initiate a landing landing. The verticle tail is
cambered to produce a sideforce in the opposite direction of the torque for
that reason.
Other than that autoratation is the other way down.
<cla...@sj.znet.com> wrote in message
news:3c00817f...@news.znet.com...
Andrew Crane
> I understand under certain conditions if the tail rotor becomes
> disabled, some helicopters can remain controlable enough to be able to
> land.
I had an interesting demonstration in an R22 recently. Whilst in forward
flight the thing crabs along quite happily with no t/r control. On slowing
up, the demonstration was to close the throttle a little to yaw the nose to
the right and open it a little to move to yaw to the left. (ie, stick one of
your throttle fingers out and steer with it).
Using this technique the instructor made an (to me anyway) impressive run-on
landing without any problem.
If it got stuck with any great pitch on it though, I'm not sure how much
value this technique would have. It's certainly worth a go compared with a
trashed chopper though.
An auto isn't going to help you because the drag of the gearbox and running
gear is going to make the thing yaw the other way.
Andrew Crane
"Andrew Crane" <ne...@inweb.net.uk> wrote in message
news:9tt2d5$a4n$1...@custnews.inweb.net.uk...
> I had an interesting demonstration in an R22 recently. Whilst in forward
> flight the thing crabs along quite happily with no t/r control. On slowing
> up, the demonstration was to close the throttle a little to yaw the nose
to
> the right and open it a little to move to yaw to the left.
...or even the other way around :-)
Regards
Andrew
Walter Hawn
> An auto isn't going to help you because the drag of the gearbox and
running
> gear is going to make the thing yaw the other way.
Gotta disagree. This is a very(!) broad(!) heading and in that sense, don't
rule out an auto. There are a go-zillion variations possible in tail rotor
failures. Train and practice as many variations as you can.
Yes, a run on with torque steering via throttle is an option with some
failure modes and some aircraft. It will also put you low, slow and
spinning if you've incorrectly assessed your situation.
Sometimes a plain old power off landing is the best option available. You
don't have to do a flight school auto from 300, 500 or 1000 feet. ( Do one
if that's what you're comfortable with and the situation requires a no power
landing.)
The yaw rate of powertrain friction is much lower than the rate possible
with power on and seriously reduced antitorque thrust.
If the aircraft is under control, keep it in control, evaluate all your
options, and fly to SURVIVE. Using the aircraft again is secondary.
180 Walt
Bob Barbanes
failures are rather benign and are "easily" handled. I dunno...
As professional pilot Walt Hawn points out, there are MANY different types of
tail rotor failures, and you can only "practice" for but a few of them.
Whether that practice has any real-world value is open for discussion.
Personally, with the exception of certain fixed-pitch scenarios, I believe that
practicing <i>any</i> other failure mode is a waste of time.
"Bart" says this:
<i> In flight with reasonable airspeed most failures allow for continued
flight. The helicopter might yaw and roll a little, but it won't spin wildly.
The fun part is landing with this situation. Newton's action and reaction law
plays a big part in these landings. The TR is there to counter the rotational
forces of the main rotor torque. If you remove that torque the helicopter will
not spin wildly. </i>
Hmm. Let's get a few things straight: The spinning tail rotor provides a
certain, quantifiable amount of disk area, which translates into vertical FIN
area. Without it...e.g. if the blades stop turning...that fin area is lost.
Gone. Back in the early 1990's, engineers at Bell did some noodling on their
new 80-286 computers and figured out that with a complete loss of thrust at
cruise power/speed, a 206 does not have enough tailboom/vertical fin area to
keep the fuselage from rotating completely around! Holy cow! The emergency
procedure for "Complete Loss of Thrust" in the AFM was subsequently and
immediately revised. Take a peek at what it says now. They mention
"uncontrolled yawing...rolling...and nose-tucking" in big, bold letters.
Ponder for a moment the implications of the fuselage yawing uncontrollably
under a teetering, semi-rigid rotor. Our low-time, sleepy, average-skilled
private pilot is at or near the controls of his 206 when there is a loud
<i>BANG!</i> The fuselage starts to yaw to the right, and as it does it
leans over (banks) to the LEFT as the side of the ship is exposed to the
relative wind. Maybe the nose even drops a little. Now, the rotor is still
cruising along in its own trim position, as it will do for a few seconds. The
confused pilot is suddenly faced with some things that need immediate
attention: The yaw, of course, which the pedals do nothing to correct; and the
roll. Instinctively, before even chopping the throttle he adds right cyclic.
But the clearance between the hub and the mast has already been decreased, and
there's not much left.
Okay, maybe the fuselage won't "spin wildly," but if things are not attended to
<i>immediately,</i> things are going to come apart in very short order.
I don't mean to pick on him, but "Bart" goes on:
<i> The key to landing with a TR failure is proper manipulation of airspeed,
torque, and altitude. </i>
Umm...IF you're talking about a fixed-pitch failure mode of some sort, I'd
agree. But just about every rotorcraft AFM (including my beloved/despised
Bo-105 Bolkow) says that after a complete loss of thrust, the procedure IS to
autorotate. I can assure you that there will be no landing with power! While
a particular helicopter <i>may</i> (or may not) be able to maintain cruise
flight with no tail rotor, landing is a different story. Again, we may have a
serious forward c.g. problem to deal with that would hamper our ability to
flare, as my friend Bob Maze found out when the tail rotor and back part of the
tailboom departed his brandy-new 407. With the power on, below a certain speed
the yawing will become uncontrollable, and below ETL the aircraft <i>will</i>
spin "wildly" (that is, "disorientingly fast").
And if you're worried about the fuselage rotating to the right due to
transmission friction during the pitch-pull at the bottom, "simply" land with a
left-quartering headwind or left crosswind to minimize it. Hey, it
<i>might</i> help.
Finally, "Bart" says:
<i> The notion that helicopters will spin wildly of the sky with any loss of TR
is probably one of the biggest misconceptions held by non helicopter pilots.
</i>
Oh yeah? I had a tail rotor failure in a hover in a 206 on an offshore oil
platform, and I'm here to tell you, the aircraft spun "wildly." There was
absolutely NO sense of lateral accelleration. One second I was hovering there,
into the wind, ready to pull pitch and go. Then I heard the proverbial bang,
my left foot went to the floor and suddenly the world was a blue sideways blur.
Oh yeah, baby! I rolled the throttle off but strangely the rotation did not
stop. (Maybe if I'd gone to "cut-off" instead of "flight-idle" it would have,
but that bright idea did not pop instantly into my pea-brain at that moment.)
Here's another thing. As the aircraft spins, the lateral forces in the cockpit
are substantial. I can vouch for this. If the pilot did not get the rotation
under control post-haste, it would be VERY easy to make an inadvertent cyclic
input that would induce a pitch or rolling moment that would be VERY hard to
correct. I'm thinking...Davey Allison's crash in that H-500 after he stuck his
tail into the fence at that racetrack. Me, I was lucky or something.
And on final thing: Depending on where the t/r failure happens, you might very
well poop a brick. There will undoubtedly be some <i>bad</i> noise associated
with the failure along with an attendant loss of some control. How bad the
situation goes from there depends a lot on your ability to rapidly and
accurately recognize and correct the various "problems" you are now faced with.
Most assuredly, your adrenalin will be pumping like the hormones of a teenager
looking at a picture of Pamela Anderson. Naked. Remember, we helicopter
pilots are spring-loaded for bad things to happen. We know (to quote Harry
Reasoner) that if something bad has not already gone wrong, it's about to. And
when that "something" does happen, we imagine the worst. <i>"Oh shit! Is this
thing coming apart?"</i> (How many times have I said that!) Even after
eighteen years in the cockpit, my heart always jumps a little when I hear any
strange or unfamiliar noise in flight. We all imagine ourselves as cool, calm
and collected, but when you start hearing really bad noises in a helicopter in
flight, your heart <i>will</i> be in your throat and that may effect how you
handle the emergency.
When it comes to tail rotor failures, things are certainly not black and white.
So good luck to you, and let's hope that your next tail rotor failure is a
simple, unnoticed empty soda can or styrofoam cup that falls under the
copilot's right pedal of your Enstrom.
Bob Barbanes
1. In my "tail rotor failure in a hover" incident in the 206, I do not know
how many times we went 'round before things finally calmed down. I
<i>think</i> it was three, because there was a certain structure on the oil
platform that I believe I saw go by three times. But from that point, I was
looking down at the helideck because a) I could sense that because of the wind,
the ship was drifting closer and closer to the edge, and, b) there was nothing
else to look at, being on an elevated helideck over 100 feet above the flat,
blue water. Hey, even I'm surprised that I didn't end up on my side, or worse,
<i>over</i> the side! Sometimes ya gets lucky.
2. I had one other tail rotor failure in a 206, this time in an L-1. Actually
it was a driveshaft failure. It was winter in the Gulf of Mexico. The night
before, in very cold, rainy, miserable conditions outdoors, my mechanic had
removed the # 2(?) t/r driveshaft for inspection (the one that comes out of the
oil cooler going back to the tail rotor). Inadvertently, he neglected to
ensure the security of the little nuts and bolts that keep the first Thomas
coupling in the driveshaft together. Four hours of flight time later that next
day, the coupling came apart on me. Fortunately this happened just
<i>after</i> setting down on an offshore oil platform. (As this was some hours
still before "downtime," I happily thought I was then done for the day, but
dang it, PHI brought another ship out for me to complete the days' runs. Get
right back on that horse!)
The winds that day were 30 knots or so. Had the failure occured in flight, the
autorotation would have been a piece of cake. Landing in the cold gulf with
waves whipped up by 30 knots of wind would've been another story and I likely
would not be as understanding of and sympathetic to my mechanic as I am now.
Point of <i>this</i> story is that when the coupling came apart, the aft end of
the # 2(?) shaft was unsupported. As it continued to rotate (driven by the
engine), it beat a BIG hole in the top of the fuselage just foward of the
tailboom attach point, and made a GOD-AWFUL noise doing it. I really can't
imagine how I would've felt if I'd been in flight when I heard that racket. It
would've been a tense ride down.
Allan Dobler
how is that book coming along? Can I look for it in the store for Xmas?
:-)
Allan
Stan Gosnell
>"So if the tail rotor disappears" I would expect those parts falling off
>in flight "disappears" a loss of the weight of the tail rotor and gear
>box that far aft from the aircraft would put the weight and balance out
>of any hope of control flight.
Maybe, maybe not. It certainly would get hairy. We had a 412 lose the 90
deg gearbox some time ago, caused by a TR blade separation. They
successfully landed it in the water, somehow. They claim it went inverted
initially, & they fought it from 5500' down to 500', where it somehow went
right-side-up. Loss of the entire gearbox certainly changes the CG
radically, & a successful recovery would be in doubt. Loss of thrust only
is a different story, & a successful autorotation should be possible,
depending on where in the flight regime it occurs.
--
Regards,
Stan
John Martin
quite quite the same as no tail rotor at all. Even with the no pedals or
full right pedal the blades are still spinning so will generates some sort
of effect, albeit not much. Now if the blades stopped completely - eg drive
train failure (flex plates separating in an R22 for instance) you now have
no tail rotor effect (except some drag)
I guess the answer to the question has to be:
Depends on aircraft
Depends on the type of "disabled"
Most rotorcraft have some tail plane which will give directional stability
if you are going fast enough. R22s are supposed to maintain directional
stability over 70 knots. I would guess some like Bell 47 with an open tail
boom and no flat surfaces may not hold direction.
Next - Type of disabled
A present but non-functioning tail rotor gives you a loss of lateral control
with no change of C of G.
A lost / damaged tail rotor and other bits may give severe vibration
problems and C of G problems and be difficult to control at all.
The handbook answer to these situations is to enter an autorotation. The
basis being - No power being directed to the blades will mean no torque on
the body therefore no need for a tail rotor.
John Martin
Andrew Crane <ne...@inweb.net.uk> wrote in message
news:9tt2d5$a4n$1...@custnews.inweb.net.uk...
>
John Martin
Sorry, I forgot to add.
Your experience of the instructor and the throttle rolling sounds more like
the jammed pedals management. This implies you still have a functioning
tail rotor but now at a fixed pitch and so you vary the torque to fit the
anti-torque rather than the other way round. This allows, as you said, good
control to do a slow run on landing. I was taught to maintain just above
translation speed of 15 knots-17 knots till just before touchdown. (well
below the 70 knots supposedly needed to maintain control with no tail rotor)
John Martin
John Martin <jo...@austarnet.com.au> wrote in message
news:9tuu81$2nn0$1...@austar-news.austarnet.com.au...
and DebrahC@ourhouse.net Mark
practiced, and the stuck pedal is not that big of a deflection. I was
a passenger with a friend when the swash plate destroyed itself on our
tail rotor. This caused no control via the pedals, but with a run on
landing it was no big deal. Did not even phase the skid shoes.
Where I work, we practice lost of tail rotor extensively, in all
configurations. I am sad that it is not drilled in during pilot
training as much as it should.
And by the way, cut the throttle with a stuck pedal in a NOTAR, and
you just created a problem that is not recoverable...
-Mark.
Walter Hawn
Bob Barbanes <bh2...@aol.com> wrote in message
news:20011126124014...@mb-fi.aol.com...
>
Snipped
Losing a flight control-say, pedals-is disorienting as all get out. Getting
beyond that and reacting appropriately takes a little time, during which
you're not really in control. Your body keeps trying to fly normally until
the brand new test pilot between your ears takes over with a plan.
The longer I fly, the more cautious I get.
180 Walt
diethelm
gyro and the SAS?
Mark <Mark and Deb...@ourhouse.net> wrote in message
news:dcf60u8q87k71d2dk...@4ax.com...
John Eacott
"Walter Hawn" <weave...@worldnet.att.net> wrote in message
news:gdKM7.199511$3d2.8...@bgtnsc06-news.ops.worldnet.att.net...
> I'd like to add an aside:
> Losing a flight control-say, pedals-is disorienting as all get out. Getting
> beyond that and reacting appropriately takes a little time, during which
> you're not really in control. Your body keeps trying to fly normally until
> the brand new test pilot between your ears takes over with a plan.
> The longer I fly, the more cautious I get.
> 180 Walt
OK, it's time to dive in here, having had the embarrassment of stuffing my tail rotor into a tree,
at night, in a 20ft hover, last month. The BK made some terribly expensive sounding noises, the
brain went into freeze frame, and the only logical thing that emerged after years of training was
"DROP THE BL**DY COLLECTIVE". I did, and by the time we got to the ground the machine had spun
through 100 degrees, and then went another 20-30 degrees on the skids. The front and rear
crosstubes spread a bit (more on the front), the t/r and 90 box landed alongside me, and lots of
noises came from aft. Shut down, packed up and went to the hotel.
Absolutely no hope of pulling engines to idle, playing clever games with the cyclic, or any other
option. Reading Bob's experience on the rig with a 206, rolling the throttle off and rotating three
times before putting it down, I'm amazed he didn't roll over. I'm sure that if I had delayed a
millisecond longer, I'd have rolled, and had far more problems (than just paying for the
repairs....).
Every in flight emergency is unique, but if you lose the t/r in the hover, get the machine on the
ground. Period.
--
John Eacott
The Helicopter Service Australia
www.helicopterservice.com.au
Stan Gosnell
<8FUM7.8$ZT5...@nsw.nnrp.telstra.net>:
>OK, it's time to dive in here, having had the embarrassment of stuffing
>my tail rotor into a tree, at night, in a 20ft hover, last month.
<snip>
My condolences.
>Absolutely no hope of pulling engines to idle, playing clever games with
>the cyclic, or any other option.
One of the greatest virtues of Bells is that you have the throttle(s) in
your hand. Having the throttle(s) on the ceiling, or floor, or anywhere
else is simple (if not gross) negligence. The other companies should just
give up, & pony up the money to license the patent. Or better yet, Bell
should allow anyone to use the throttle-on-the-collective scheme. Anything
else is just insane. With the throttle in your hand, you can get to idle
at the same time you're lowering the collective. Anywhere else, & you're
up the creek, as you discovered. There's just no way to manipulate the
throttle anywhere else.
--
Regards,
Stan
bl...@nospam.com
Gosnell) wrote:
>One of the greatest virtues of Bells is that you have the throttle(s) in
>your hand.
I thought the H/MD500E has the throttle on the collective as well?
Dave Blevins
John Bicker
wrote:
WTF is a "hovering autorotation?". I assume you mean power failure in
the hover. In most cases I doubt that the helicopter enters autorotation
in the hover.
John Bicker
"Peter Seddon" <pe...@seddonp.freeserve.co.uk> wrote:
> The tail rotor is there to counteract the main rotor torque. So if the tail
> rotor disappears then cut the engine and you may be able to autorotate
> safely to the ground. This I beleieve is the only way you will fly without a
> tail rotor.
>
> Regards Peter
>
Beauty! Thanks for that. I am now taking a jiffy saw to all the
hellicopters that I fly. Damn stabilisers - who needs em? Will post
details of the improvements here.
John Bicker
stang@[204.52.135.1] (Stan Gosnell) wrote:
An SA 330J did about the same sort of maneuver after a TR blade departed
rapidly followed by the TRGB due to the imbalance. It started at about
6000' and completed a few loops and rolls and hit the water roughly the
right way up luckily. Just flying some of these larger types with the
SAS off lets you know about yaw/roll couples let alone with the C of G
outside the envelope. A 109E and S 76 A are examples. These types are
actually elastic in yaw/roll or try to be if where they crack is any
guide.
Bart
>
> WTF is a "hovering autorotation?". I assume you mean power failure in
> the hover. In most cases I doubt that the helicopter enters > > >autorotation in the hover.
I didn't name it; I was trained at the factory and thats what they
called it. Chop power and raise the collective smoothly until you
touch down. If you catch it fast enough the helicopter won't even
spin that much.
Bart
Walter Hawn
> the hover. In most cases I doubt that the helicopter enters autorotation
> in the hover.
Hovering auto is a controlled landing without engine power.
Walter Hawn
I'm solidly with Stan-throttles on the collective! When the antitorque is
compromised, throttles are primary flight controls.
180 Walt
bl...@nospam.com
Some folks would say that it's not an auto since the direction of the
airflow passing through the main rotor disc does not have time to
reverse in this maneuver... I personally prefer "power failure in a
hover".
Dave Blevins
and DebrahC@ourhouse.net Mark
no control of the thruster (right vertical has 29 degrees, connected
to the thruster and control of the thruster fan). Another thing about
the gyro for the YSAS is that if you are in an orbit (or any turn) for
more then 15 or 20 seconds, it will reset to the amount of pedal you
have in and keep it there. That is great, but when you straighten out
and fly straight you have to fight the gyro until it resets. It really
is only for stopping the dang tail from fish tailing all over the
place in normal flight and does not have enough authority for any
anti-torque failure.
Per the book: Fixed anti-torque failure has a warning and to quote
"Use a powered landing, otherwise it is unlikely that an autorotation
can be accomplished."
There are other warnings/cautions about being slower then 20 kts. and
not to perform an auto unless the engine really quit.
A real fun helicopter if something in the back breaks....
-Mark
joe landy
I'm a Model Heli pilot, not fullsize, and I notice someone mentioned having
yaw control during auto, and talked about the friction of gearboxes e.t.c.
With a model, the freewheel hub (autorotation unit) is mounted last in the
drivetrain before the rotors, hence as soon as the engine stops, all you can
do is land, and the only steering is done with cyclic, e.g by rolling. Is
this not the case with a full size jobby?
Also, I always wondered whether it's possible to fly/auto a twin rotor heli
with one rotor stopped. I know the CH46, CH47 e.t.c have intermeshing
rotors, but they are at different heights on their pylons are they not? I
just wondered is it was possible to land one with, say full forward cyclic
on the front rotor, should the rear one die. Also, what about some of the
other twin rotor machines, e.g with spaced out rotor masts? Just interested!
If anyone's interested, you can see a Bell 206 jet ranger yaw and roll in
the film Blue Thunder, but the Observer in the heli who shouts Mayday says
they've got a Broken elevator? Surely not, the engine revved up to full
power, and they appeared to lose tail control!
I read an accident report on a gazelle where the heli had lost tail control
at just 100 feet from takeoff. The pilot got disorientated and crashed very
quickly. I had a friend advise me that if the pilot had tried to gain
forward speed quickly, the heli would have been controllable with the effect
of tail fin! Not sure the pilot would have thought about much else than
getting to the ground safely though!
Hover-auto? With a model, if we're hovering at, say 10 feet, and the engine
dies, we just hold collective where it was, and the heli sits down
comfortably on the ground! Magic. I would say that this could be named the
hover auto!
The pitch is obviously so much higher in the hover than in forward flight
that it's about right for an immediate cushioned landing.
Cheers all.
Apologies if nothing I said applies to full size craft!
Joe.
"John Martin" <jo...@austarnet.com.au> wrote in message
news:9tvdss$2vg0$1...@austar-news.austarnet.com.au...
Walter Hawn
installation.
In case of an engine failure, the main rotor will drive the tail rotor
through the tranny via the t/r drive shaft, as normal.
In autorotaion, one flys the aircraft normally-except you're trading stored
energy (altitude and speed) for lift.
Twin rotors are also twin wings-losing a wing shortens a flight suddenly and
drastically.
180 Wally
joe landy
rotors break or fall off? It seems to be a fairly widely known problem with
tail rotors, they break or fall off, is this due to the high speed and
higher stress, or as someone else pointed out, because people hit the tail
while on the ground?
I'm surprised that the freewheel is on the engine side of the transmission,
I guessed the rotors would have stalled fairly quickly due to the ratio of
gearing, especially in a turbine helicopter.
I remember the Chinook crash in scotland where transmission failed,
resulting in loads more of them being grounded. Tragic it was, I wondered if
Twin rotored machines are overall safer? I guess it's difficult to compare,
because there are so fewer of them in service.
Safe flying all.
Joe.
Peterborough
UK.
"Walter Hawn" <weave...@worldnet.att.net> wrote in message
news:S05O7.138560$WW.87...@bgtnsc05-news.ops.worldnet.att.net...
The Walkers
"joe landy" <joela...@postmaster.co.uk> wrote in message
news:9uaplg$kch$1...@news7.svr.pol.co.uk...
> Thanks for that walter.
stuff snipped.
Just to add to Walt's excellent post, another reason to put the clutch on
the input side of the transmission is to allow the autorotating main blades
to power some very important aux systems, like the hydraulic pumps. Loss of
hydraulic pressure on anything bigger than a Jetranger is usually fatal.
Concerning an earlier question about tandem rotors, you should remember that
the discs may appear to be in different horizontal planes, but the
individual blades flap enough to run into each other. Loss of the synchro
shaft generally results in blades hiting each other and departing the
helicopter. Nasty results follow.
Even loss of a small part of a blade can produce vibrations (due to the
imbalance in the rotating mass) that can ruin your day. I examined a BK117
many years ago that had sucked part of an engine cowling into the main
blades. All four blades lost a foot or two of the foam cored section of the
blade behind the unidirectional glass spar, in close to the hub. The lost
mass was less than a pound per blade, and was roughly equal off each of the
blades. The resulting imbalance reportedly made in impossible for the pilot
to read any gauges, and hard to keep a grip on the controls. He was very
near an airport, and landed within a few minutes at the first level spot he
got to.
BW
joe landy
on Tandem rotor craft (by that chap who was in desert storm e.t.c, good
website) that when autorotating a Chinook, if rotor speed got too low, the
generators would fail, and the wheel castoring brakes would go on, so when
you landed, if the craft was moving in any direction different to where the
wheels were pointing, it'd probably tip over!!
Thanks for the info, I never thought about all the auxilliary equipment
needed to keep control of the heli.
On another note, I work in a small company where we sometimes use some
German servo control gear. Upon attending their 50th anniversary show
recently, we were shown their method of counteracting the vibrations from
rotors by inputting a small pitch movement to oppose the vibration. The way
they sense the vibrations and respond to them is quite incredible!
It's amazing what this company applies it's servo systems to.
I guess this system could make a helicopter with a damaged rotor blade more
controllable.
With models helicopters, we also get severe vibration if we don't balance
the blades accurately, and if the Centre of gravity of each blade doesn't
occur in the same place along it's length.
"The Walkers" <bwalkerd...@ody.ca> wrote in message
news:oYbO7.68030$Z2.9...@nnrp1.uunet.ca...
Badwater Bill
<ne...@inweb.net.uk> wrote:
>
>"Andrew Crane" <ne...@inweb.net.uk> wrote in message
>news:9tt2d5$a4n$1...@custnews.inweb.net.uk...
>>
>> <cla...@sj.znet.com> wrote in message
>> news:3c00817f...@news.znet.com...
>
>> I had an interesting demonstration in an R22 recently. Whilst in forward
>> flight the thing crabs along quite happily with no t/r control. On slowing
>> up, the demonstration was to close the throttle a little to yaw the nose
>to
>> the right and open it a little to move to yaw to the left.
>
>...or even the other way around :-)
>
>Regards
>Andrew
Okay. I was thinking that too...I'm glad I'm right (correct). If you
extend your index finger below the collective so a roll on of power
makes your finger move right, the nose will go to the right. If you
reduce power, your index finger will point more to the left and your
nose will go left...unless you are flying an Astar or something with
reverse rotor rotation.
Bill
Badwater Bill
>The yaw rate of powertrain friction is much lower than the rate possible
>with power on and seriously reduced antitorque thrust.
>If the aircraft is under control, keep it in control, evaluate all your
>options, and fly to SURVIVE. Using the aircraft again is secondary.
>180 Walt
>
I might rewrite that last sentence to say "Losing the aircraft is a
secondary consideration. The aircraft is expendable, we are not." I
think too many people try to preserve the machine instead of
themselves and end up dying over it. I like your attitude Walt. "FLY
TO SURVIVE."
Bill
Badwater Bill
It does.
Bill
Walter Hawn
The ECL? er...
FFL?
THROTTLE!!! is a lever down on the floor beyond the collective and works
backwards-pushing it down "opens the throttle" until you go too far, and
then it's in manual, governor over-ride.
I'm learning new french cuss-words every day.
180 Walt
John Bicker
"The Walkers" <bwalkerd...@ody.ca> wrote:
> "joe landy" <joela...@postmaster.co.uk> wrote in message
> news:9uaplg$kch$1...@news7.svr.pol.co.uk...
> > Thanks for that walter.
>
> stuff snipped.
>
> Just to add to Walt's excellent post, another reason to put the clutch on
> the input side of the transmission is to allow the autorotating main blades
> to power some very important aux systems, like the hydraulic pumps. Loss of
> hydraulic pressure on anything bigger than a Jetranger is usually fatal.
Gee! From memory I think the 205/212 is manageable sans hydraulics. In
fact in a 205A1 above about 40 knots the loss of hydraulics in the
cyclic is not noticeable. The collective is the bummer in the 212. A few
tricks needed there.
Stan Gosnell
news:johnbicker-86838...@news.compuserve.com:
>> Just to add to Walt's excellent post, another reason to put the clutch
>> on the input side of the transmission is to allow the autorotating
>> main blades to power some very important aux systems, like the
>> hydraulic pumps. Loss of hydraulic pressure on anything bigger than a
>> Jetranger is usually fatal.
>
> Gee! From memory I think the 205/212 is manageable sans hydraulics. In
> fact in a 205A1 above about 40 knots the loss of hydraulics in the
> cyclic is not noticeable. The collective is the bummer in the 212. A
> few tricks needed there.
It certainly isn't easy, but it is doable. I remember having an IP in the
Army shut off the hydraulics in a UH1, & having me land it to a hover, then
set it down. It's work, but it is possible. The Army's book solution was
a running landing, but book solutions aren't always available, & he was
teaching me survival.
--
Regards,
Stan