LTE does not affect all Helos!
nla...@bellsouth.nospam.net
to blame pilots for airplane problems:
While your opinion is theoretically correct, the practical issue is that
several helos are woefully inadequate in basic tail rotor authority, and are
therefore more likely to experience LTE.
The term LTE is itself a misnomer, in that it infers that somewhere the
perfectly normal and acceptable tail rotor gets blanked, or stalls or somehow
becomes ineffective. This is simply not supported by the data, or by the
military tests that have been conducted.
LTE is found on helos that have poor tail rotors, where the yaw thrust margins
are low in normal maneuvers. With low margins, the type and severity of
maneuver that absorbs all the anti-torque is much more likely to be
encountered. On helos with powerful tail rotors, LTE is non-existant I defy
you to find legitimate LTE in a Black Hawk, or an Apache or an S-76.
LTE is cured in two ways:
1) In shitty helicopters, baby them as you maneuver at low speed, especially
with regard to collective pitch applications in descent with cross or down
winds.
2) get a helicopter with a better tail rotor, and you will never see LTE
unless you purposely induce it. The proof is the US Army yaw maneuver
criteria improvement over the last 30 years, which has eliminated LTE in the
new designs. In 1965 (H-1, H-58), all you needed was 17 knots of sideward
flight capability. In 1978 (Ah-64, UH-60) you had to show 45 knots at
altitude). In 2000 (Comanche), you have to show a snappy hover turn at 45
knots.
LTE is not a problem in any helicopter that meets the modern yaw maneuver
criteria. PERIOD
Why do I rag on this way? Because if we all don't help keep the issue
understood, we will always have to fly crappy helicopters where some well
meaning but misinformed guy can simply blame the pilot (Meshnet said "which I
prefer to call "LPE", for "Loss of Pilot Effectiveness").
Modern helos can eliminate the need to blame the pilot by eliminating the need
to baby the machine. The Army forced the redesign of the OH-58D to eliminate
LTE, which they found when doing simple bob-down maneuvers.
Why stop at LTE, Meshnet? let's blame all those pilots for the post crash
fires, and eliminate crashworthy fuel systems. Those stroking seats are for
wimps who can't really fly, lets just break the backs of the assholes, ("Loss
of Crappy Pilot") and eliminate the problem through Darwinism!
Seroiusly, I believe we must learn to criticize the job we are given, and the
machines we use, if we are to make progress in our industry. I joke that the
only difference between a test pilot and a regular pilot is that the test
pilot is allowed to blame the machine.
Learn to blame the machine, learn to fix the heliport, learn to say no to the
night semi-IFR mission, and maybe our loss rate will improve, our customers
will be safer, and our insurance rates will drop.
Every airliner lands on the same runway, same width, same markings. They make
their living changing the environment to fit their needs. They force standard
angles, clearances, dimensions and procedures, and so they get impeccable
safety - 10 times the safety we do.
We in Helo-land (45 clicks south east of Pepperland) are very willing to land
in an LZ with a telephone pole in the center, to fly VFR at night in 500 and
1, to lift the boss over a set of wires at his heliport without complaint.
And when we hit that pole, run into the terrain, or snag that wire, we blame
the pilot, a poor shmoe who only has 2500 hours and 7 tears experience.
This attitude has to stop - we have to stop trusting the "Right Stuff" to keep
us out of the woods. We have to start expecting to get aircraft that are
relatively easy to fly, systems that help us do the job and operating
environments that help us keep safe.
We don't have to look too far for examples. Lose 3 helicopters in ice fog,
anyone? Do you think the average person thinks helo pilots are fools? Do you
think we looked foolish? Do you think a guy in Alabama will think twice about
a charter because of that Alaska incident?
Wow! Did I get carried away, or what?
Nick
mr_rot...@my-deja.com
Sent via Deja.com http://www.deja.com/
Before you buy.
Phil Bridges
----Lots of good stuff deleted-------
>Seroiusly, I believe we must learn to criticize the job we are given, and the
>machines we use, if we are to make progress in our industry. I joke that the
>only difference between a test pilot and a regular pilot is that the test
>pilot is allowed to blame the machine.
>Learn to blame the machine, learn to fix the heliport, learn to say no to the
>night semi-IFR mission, and maybe our loss rate will improve, our customers
>will be safer, and our insurance rates will drop.
I agree, Nick, and I think there are two problems that drive this. The
first is that many pilots have never flown a good helicopter and thus have
no reference with which to compare. I flew Hueys and 58A/A+ for 22 years.
If you asked the pilots in my unit how these aircraft flew, they thought
they flew great, if they had never flown in a modern helicopter with SAS.
And yet a two hour IFR or NOE mission would leave you exhausted from the
pilot workload, since the pilot is continually closing the loop in controlling
an unstable aircraft. The second is that, at least in the Army, pilots
are continually expected to perform tasks without the proper equipment.
A friend of mine was killed in an OH-58D while hovering over a large
grove of pine trees at night under NVG. The aircraft drifted rearward and
hit a large pine sticking out above the grove. The Army called it pilot
error, but as the Navy and Coast Guard has known for a long time, it is
practically impossible to precisely hover over featureless terrain (the
ocean). Large areas of pine trees, all swaying under the rotor wash,
produce the same effect. Yet no changes will be made, just the comment
that somehow an experienced combat veteran screwed up and lost his lift.
Blame the pilot, not the machine or the mission.
--
| Philip Bridges | "Strive for design simplicity: |
| Dept. of Aerospace Eng. | you never have to fix anything |
| Drawer A, 330 Walker Eng. | you leave out." |
| Miss. State, MS 39762 | Bill Lear (1903-1978) |
Matthew
we can always blame the machine. No matter what machine you give me, there
are limitations and I can exceed them. That does not make a bad design. In
the case of LTE you're right that with today's technology there should be no
reason that today's helicopter's suffer frequent bouts of LTE. Fact is
everyone doesn't fly today's aircraft. They are flying yesterday's aircraft
today and will be flying the same machine tomorrow.
LTE has been extensively studied, is now understood, so two things should
now happen. First, engineers should not design helicopters that are subject
to "LTE" and second, pilots in helicopters with known limitations concerning
LTE should not fly into "LPE". I don't think all cases are pilot induced,
but when you hear of a pilot encounter LTE in a machine prone to it, and the
pilot doesn't understand it, I can't blame this on the engineers.
Matthew.
nla...@bellsouth.nospam.net wrote in message ...
>Seroiusly, I believe we must learn to criticize the job we are given, and
the
>machines we use, if we are to make progress in our industry. I joke that
the
>only difference between a test pilot and a regular pilot is that the test
>pilot is allowed to blame the machine.
>
>Learn to blame the machine, learn to fix the heliport, learn to say no to
the
>night semi-IFR mission, and maybe our loss rate will improve, our customers
>will be safer, and our insurance rates will drop.
>
nla...@bellsouth.nospam.net
>Nick, I see your point, and agree with it to an extent. I don't think that
>we can always blame the machine. No matter what machine you give me, there
>are limitations and I can exceed them. That does not make a bad design. In
>the case of LTE you're right that with today's technology there should be no
>reason that today's helicopter's suffer frequent bouts of LTE. Fact is
>everyone doesn't fly today's aircraft. They are flying yesterday's aircraft
>today and will be flying the same machine tomorrow.
>
>LTE has been extensively studied, is now understood, so two things should
>now happen. First, engineers should not design helicopters that are subject
>to "LTE" and second, pilots in helicopters with known limitations concerning
>LTE should not fly into "LPE". I don't think all cases are pilot induced,
>but when you hear of a pilot encounter LTE in a machine prone to it, and the
>pilot doesn't understand it, I can't blame this on the engineers.
>
>
>Matthew.
>
Matthew,
I think you are also quite correct, but the problem is that even brand new
designs are being allowed to be introduced with no yaw control margin. Two
that come to mind are the B-430 and the B-412, both have a special "Catagory B
9 passengers or less FAA approval" where they must be operated with the "wind
within 45 degrees of the nose" and they do not have to demonstrate any
anti-torque margin (pedal margin) beyond that necessary to sneak out of a
hover with the wind off the nose.
If we are to make a difference as time goes on, we must improve our
instruments, nav systems and hardware to get better in every way.
If we allow ourselves to simply blame the pilot, we won't grow. The fact that
we have the accident rates that we do, and that "pilot error" is the cause 2/3
of the time should make us reflect. Our customers don't want excuses, they
want an entire system that works without hurting them.
Nick
Robert Wittmann
nlappos
>
>Matthew,
>
>I think you are also quite correct, but the problem is that even brand new
>designs are being allowed to be introduced with no yaw control margin. Two
>that come to mind are the B-430 and the B-412, both have a special
"Catagory B
>9 passengers or less FAA approval" where they must be operated with the
"wind
>within 45 degrees of the nose" and they do not have to demonstrate any
>anti-torque margin (pedal margin) beyond that necessary to sneak out of a
>hover with the wind off the nose.
>
>If we are to make a difference as time goes on, we must improve our
>instruments, nav systems and hardware to get better in every way.
>
>If we allow ourselves to simply blame the pilot, we won't grow. The fact
that
>we have the accident rates that we do, and that "pilot error" is the cause
2/3
>of the time should make us reflect. Our customers don't want excuses, they
>want an entire system that works without hurting them.
>
>Nick
Hello Nick,
thank you for commenting this toppic and putting it on a practical basis.
I think that good yaw controll is a must in modern helicopter design.
Therefore I felt very uncomfortable with the helo of a friend of mine during
hover at approximately 5 to 8 kts wind because it was impossible to do a
hover normal to wind direction at 100% RotorRPM.
He then told me to increase RPM to 107% to get more power to the tail-rotor.
I tried and it worked. But in the end this shows that the tail-rotor is
underdimensioned and I think that such a bad design is not tolerable even if
it is a homebuilt helicopter (a modified CH7 with increased mass and power
but the unchanged fuselage and blades of the standard version).
The criteria for flight test demonstration you cited (45kts normal to wind
direction) were new to me.
So my question is where can I find the original regulations for this flight
tests?
Are they appended to a FAR or ...US.Ariforce/Army.Technical.Orders or ... ?
Thanx for your help and
kind regards from Germany,
Robert
Walter Hawn
We ought to teach this at every commercial level course, at least. All
helos aren't designed to the same standard no matter how similarly they
seem to fly.
180 Walt
Meshnet
be designed so as to minimize the probability of LTE/LPE. None the less,
given the proportion of the helicopter population that does not meet current
military design standards for tail rotor authority, and the proven fact that
*any* single main rotor helicopter can, at least theoretically, get into
this problem, pilots have to fly the machines they are given. We aren't
going to retroactively change the helicopter population, and the beasts seem
to live forever, so for well into the 21st century many of us, and our
children, can expect to fly machines designed to 1960s and earlier
standards.
In that context, it is difficult to dispute that helicopters designed to
meet a lesser tail rotor authority requirement are less forgiving of pilots
who lose situational awareness or fly in defiance of the known limitations
of the aircraft. Interestingly, because of their other, more benign,
characteristics, Nick's personal bete noir, the 206 series, has the lowest
risk of serious accident of any commercial turbine helicopter. One of the
reasons there are so many of these helicopters, besides their reliability,
maintainability, low DOCs, and general practicality, is that the design
tradeoffs and compromises that went into their now mature (obsolescent?
obsolete?) technology has made them inexpensive to buy. They certainly do
have drawbacks for ground surveillance at low airspeeds. On balance, the
206 is still a good design, very forgiving of pilot error -- except for
excessively hot approaches or loss of situational awareness at slow
airspeeds. Talk to Don Bloom. He'll tell you how difficult it is to get
into "LTE" while you are actually paying attention to your flying.
I have flown at least one representative of every Bell military and
commercial model helicopter ever built, except for the HSL-1 tandem rotor
machine, and have a keen awareness of many of their performance compromises.
I have flown a number of competing rotorcraft, and they have compromises,
too. I hope we all manage to survive both our new, compromised designs, and
our old ones.
Matthew
>
>I think you are also quite correct, but the problem is that even brand new
>designs are being allowed to be introduced with no yaw control margin. Two
>that come to mind are the B-430 and the B-412, both have a special
"Catagory B
>9 passengers or less FAA approval" where they must be operated with the
"wind
>within 45 degrees of the nose" and they do not have to demonstrate any
>anti-torque margin (pedal margin) beyond that necessary to sneak out of a
>hover with the wind off the nose.
That just shouldn't be necessary.
>If we are to make a difference as time goes on, we must improve our
>instruments, nav systems and hardware to get better in every way.
>
>If we allow ourselves to simply blame the pilot, we won't grow. The fact
that
>we have the accident rates that we do, and that "pilot error" is the cause
2/3
>of the time should make us reflect. Our customers don't want excuses, they
>want an entire system that works without hurting them.
Actually, in a way it is good that the PROPORTION of pilot error causes is
increasing because that will happen when mechanical failures are decreasing
in number. I doubt if we'll ever be able to completely eliminate pilot
causes, because humans are so fallible. It may be possible to
next-to-eliminate mechanical causes as technology and manufacturing advance.
Of course, it's bad when actual numbers of pilot error incidents are on the
rise.
Matthew.
RW Walker
"Matthew" <c_a...@bc.symREMOVEpatico.ca> wrote in message
news:fTIS4.4686$iD.8...@news1.rdc1.bc.home.com...
>I don't think all cases are pilot induced,
> but when you hear of a pilot encounter LTE in a machine prone to it, and
the
> pilot doesn't understand it, I can't blame this on the engineers.
>
>
my pet peeve about the way some people use this term.
Too many people, educated by the mass media, think "pilot error" simply
means the pilot screwed up. Really, "pilot error", or any human error, lays
the blame on the whole aviation community.
We supposedly design and build helicopters that won't crash, and train
people to not crash, and finally tell them, in law, not to crash. When
somebody does crash, like in your example of "the pilot doesn't understand
it", this whole system is under suspicion.
Too many people take "human error" as an excuse to stop looking for a
reason, and a cure. Really, it should be a wake up call to everybody
involved.
Bill "don't get me started" Walker
nla...@bellsouth.nospam.net
>Amazing though Nick might find this, I agree that helicopters can and should
>be designed so as to minimize the probability of LTE/LPE. None the less,
>given the proportion of the helicopter population that does not meet current
>military design standards for tail rotor authority, and the proven fact that
>*any* single main rotor helicopter can, at least theoretically, get into
>this problem, pilots have to fly the machines they are given. We aren't
>going to retroactively change the helicopter population, and the beasts seem
>to live forever, so for well into the 21st century many of us, and our
>children, can expect to fly machines designed to 1960s and earlier
>standards.
Nick sez:
Meshnet seems right, but the truth is that every year, many more brand new
aircraft are delivered that do not meet reasonable standards for yaw control.
There is little excuse for building these new ones while you claim that you
can't "retroactively change" the population. Just change the new ones,
Meshnet!
The reason that there is no outcry for better aircraft is that attitudes like
this foster the belief that the pilot is responsible for the shortfalls of the
machine. While the theory of LTE being universal is interesting to Meshnet,
the fact is that most helicopters never experience it, while some aircraft
have 10 to 20% of their accidents as a result of LTE. It is self-serving to
spread the name LTE across all single rotor helicopters so as to bury the real
shortfall of a few.
Meshnet wrote:
.... Nick's personal bete noir, the 206 series......
Nick sez:
I have nothing against any particular model helicopter, I think the 206 is a
classic.
I have a tough time with people who take one aircraft's shortfall and claim
that , really, you know, every helo does it and you know, besides like the
pilot really has to screw up and you know, lets just chuckle and call it LPE.
Tell the joke to the folks who buy a helicopter in the year 2000 without
knowing that it barely meets 1965 requirements, and that 15% of its accidents
are caused by LTE that could be cured with a little attention to the tail
rotor, just like the Army made the OH-58D finally measure up.
The last time I heard an attitude like that was from an accident investigator
who briefed our pilots and ragged on about pilot error. We threw him out of
the briefing, because even LPE is in the end, our problem, isn't it Meshnet.
Nick
mr_rot...@my-deja.com
helicopter manufacturer discussing the myth of twin engine safety in
helicopters.
To an audience comprised principally of twin engine operators, he
stated that all the second engine did, was to keep running to the crash
site!
It described HIS products perfectly!
neil fraser
For those of us not familiar with the OH58D , what did they do to fix it ?
. Isn't the 407 drive train based on the OH58D ?
A larger tail rotor would be the obvious answer , but that would increase
the power required by the TR at hover and require some beefing up of the
tail boom and maybe the TR shaft to handle the extra thrust.
Do you have any info on the power required at hover for the tail rotor of
various conventional and Notar or Fenestron tail rotors ?.
BTW I saw your bit on the learning channel , funny how people don;t always
look like you would expect them to.
Completely off topic I see the Web site refers to the S92A no longer th S92
, is this still the basic version that was test flown or have significant
mods been made ?
Neil
nla...@bellsouth.nospam.net wrote in message ...
nla...@bellsouth.nospam.net
>
>For those of us not familiar with the OH58D , what did they do to fix it ?
>
>A larger tail rotor would be the obvious answer , but that would increase
>the power required by the TR at hover and require some beefing up of the
>tail boom and maybe the TR shaft to handle the extra thrust.
Nick sez:
Yes, a larger tail rotor and (I think) a beefup of the drive system). The 407
does share the parts of the 58D, I am told. Remember that the measure of yaw
control is the balance between thrust of the tail rotor and the amount of
anti-torque needed.
It is possible to take a helo with good hover yaw control and load it up by
increasing the gross weight until it has little or no yaw margin. It is
really the balance of yaw thrust and main power/lift that counts. I am
disturbed at the trend by Bell to publish and qualify "extra" gross weight
capability that is based on decreasing the yaw control until it is almost
non-existant. Any helicopter that must be hovered and taken off with the wind
only off the nose is not a good one, in my book. While it might work in some
environments, anyone who tries to maneuver into a rig, or land at a
mountainside at night might find themselves bouncing off the pedal stops to
keep things right. There is no excuse for that in today's world, and
Eurocopter, Westland, Agusta, Mil, Kamov, Hindustani Helicopters and Sikorsky
all know that.
The "catagory B" rating for the newer Bell models is a conscious effort to
water down the yaw control to gain more lift and payload. This is exactly
opposite to Meshnet's assertion that only older designs are the problem, and
we have to live with them because we don't want to redesign them. In fact,
there are brand new designs being produced and sold that require the pilot to
baby them in yaw make it work, and the first time one of those aircraft has an
LTE problem, those salesmen will get out the Pilot Error rubber stamp and
start telling everyone how crappy the pilot was, and how great the helicopter
(with almost no yaw) really is.
>Do you have any info on the power required at hover for the tail rotor of
>various conventional and Notar or Fenestron tail rotors ?.
Nick sez:
The power needed in a steady hover, where you measure performance and where
the payload is computed, is probably less for a larger tail rotor, since the
larger rotor is more efficient, and uses less power to produce the same
thrust. That means that, except for the weight of the drive system, a larger
more powerful tail rotor can increase the power that the main rotor gets,
since the tail would use less.
It is not the steady hover tail rotor power that sets the size of the drive
train, but rather the peak power. At peak, the power is determined by the max
pitch range of the tail rotor, which also determines the max thrust. The
problem is that as density altitude goes up, you need more pitch to get the
same thrust/power. This means that if you design the shafts and gearboxes for
a high altitude sideward flight capability, they have to withstand more stress
at low altitude when you use all the pitch to produce "too much" thrust.. The
Bell drive trains now are starting to use a smart tail rotor pitch stop that
allows more pitch at altitude, but prevents the high thrust at low altitude.
Scott Gradner can tell us more about that, he helped develop it.
The power requirements of a tail rotor are relatively small in normal hover,
anout 3% of the main rotor, or so. The peak power might be from 12 to 25% of
the main rotor power. For the Fantail on Comanche, the peak power could be as
high as 40% of the main power. The snap turn needs this much power, but the
capability has no real civilian use, so we rejected the big Fantail for civil
helicopters. At a steady hover, the Comanche Fantail uses almost exactly the
same power as an equivilent tail rotor, because the duct helps to double the
efficiency of the small fan.
The point about the power the tail rotor needs is that it is small, and not a
large driver in the overall design, and that it takes a certain amount to be
in the game. Why don't we argue about the amount of longitudinal cyclic?
What if a certain type of helo seemed to have a propensity to pitch up
uncontrollably if a pilot wandered into a corner of its envelope, would we
make excuses for it, and blame the pilot?
>BTW I saw your bit on the learning channel , funny how people don;t always
>look like you would expect them to.
Nick sez:
yea, I wish I looked like Brad Pitt, and so does my wife!
>Completely off topic I see the Web site refers to the S92A no longer th S92
>, is this still the basic version that was test flown or have significant
>mods been made ?
>
Nick sez:
All programs have growth built into them, but I am surprised at an A
designation! There is only 1 S-92 right now, but check back in 10 years or
so!
Nick
neil fraser
The S-92A Helibus, Sikorsky's newest medium-lift helicopter, is taking off.
Currently under development, the Helibus first flew in December 1998 and
certification is expected in 2001.
Based on U.S. Army BLACK HAWK and U.S. Navy SEAHAWK helicopters, the S-92A
will serve a variety of commercial and international utility needs,
including passenger (19-22 capacity), cargo, aeromedical, search and rescue
and resource development support. The Helibus is also designed for offshore
oil and executive transport use. With its low purchase price and operating
cost, roomy interior and noise suppression, the S-92A stands to become one
of Sikorsky's most useful and versatile helicopters to hit the skies.
Taken from Sikorsky web site , but we all know marketing people can't spell.
Thanx for the very informative answer , in a conventional TR would it be
better to have the TR suck air past the Verical stab of blow air past to
achieve the anti torque of is their very little difference.
In a different life in the UK there was story of when they reversed the
direction of the tail rotor on the Lynx ( to try to improve the performance)
but forgot to change the oil pump , so it scavanged oil from the gears
rather than pumped oil onto them.
Coulda been an urban legend though , of course the Commanche can run dry for
quite a while .
Neil
nla...@bellsouth.nospam.net wrote in message ...
Shaber CJ
>. Isn't the 407 drive train based on the OH58D ?
>
Does the OH58D have the same problems as the 407 with the tail rotor
transmission and cutting the boom off?
Dave Anderson
Small correction. Mil has sorry tail rotors. Most would not meet the
basic FAR 29.143 requirements of 17knots flight in all directions at
critical CG and lowest allowable rotor rpm. This is true of the Mil-2,and
8. The mi-14,17, and 24 are marginal. Kamov aircraft are co-axial and do
not have tail rotors and I did not do critical azimuth tests on the Ka-32.
Bell developed a type of density altitude compensator for the 206-L4(I
think this is the only model). It is certified and for sale. The Russians
were the first to do this with a system called "Movable Stops" which moves
the right pedal stop allowing more pedal authority. Their system detects
the D.A. and provides the signal for the actuator to move the stop. The
Russian rotors rotate in the opposite direction
as ours, so they have to hover with right pedal forward.
Global Helicopter (where Scott Gardner and I work) has developed a
similar system for the UH-1H for use with conversions to more powerful
engines. The civilian 205 series have all been converted to either tractor
tail rotors or the 212 system. The Army never did this, so most of the
civilian UH-1's have a pusher tail rotor that turns in the less efficient
direction, leading edge of the TR blade forward on top.
Dave Anderson
<nla...@bellsouth.nospam.net> wrote in message
news:shqr6f...@news.supernews.com...
> neil fraser wrote:
> >
> >For those of us not familiar with the OH58D , what did they do to fix it
?
Meshnet
<snip>
> Tell the joke to the folks who buy a helicopter in the year 2000 without
> knowing that it barely meets 1965 requirements, and that 15% of its
accidents
> are caused by LTE that could be cured with a little attention to the tail
> rotor, just like the Army made the OH-58D finally measure up.
The problem with this is that LTE cannot be cured "with a little attention
to the tail rotor". If you take a look at the OH-58D, and for that matter,
the 407, you can begin to see the tradeoffs that would be involved. You
certainly would have to increase the weight and structure of the tailboom
and the power output of the engine to provide for more tail rotor thrust.
The increase tail weight would require more ballast forward, which would
reduce payload and range, and the power increase would also impact range.
By the time you got through with the process, you wouldn't have a
recognizable 206 anymore, especially in terms of function and price. You
would probably have a 407. Guess what? That ship has tradeoffs in its
design, too. Show me an aircraft that doesn't!
It is not unreasonable for Nick to suggest that we discontinue legacy models
that have unsafe characteristics. If you were to really work on the
statistics, though, I suspect you would discover that, once you adjust for
the relative populations of 206s versus other models, and adjust again for
the relative presence of 206s in SkyCam and police operations versus other
models, that you will find that the 206 doesn't have quite the LTE problem
it has been blamed for. If LTE accounts for 15-20% of 206 accidents -- and
I don't know that this is correct -- is this at least partially a result of
the lower number of 206 accidents from all other causes?
Having said this, I don't dispute that the 206 was designed to an earlier
standard, or that it may be less forgiving than some, or most, other similar
helicopters. I am saying that we make tradeoffs on safety versus price,
performance, and time every time we get in our cars, much less in our
helicopters. The 206 bears up well on safety when you look at the totality
of it. Would it be a safer helicopter if you made all the tradeoffs
necessary to give it the same performance, but with greater tail rotor
authority? Maybe. Would anyone pay the price. I doubt it. The market
will decide.
Nick Lappos
>The problem with this is that LTE cannot be cured "with a little
attention
>to the tail rotor". If you take a look at the OH-58D, and for
that matter,
>the 407, you can begin to see the tradeoffs that would be
involved. You
>certainly would have to increase the weight and structure of the
tailboom
>and the power output of the engine to provide for more tail
rotor thrust.
>The increase tail weight would require more ballast forward,
which would
>reduce payload and range, and the power increase would also
impact range.
>By the time you got through with the process, you wouldn't have
a
>recognizable 206 anymore, especially in terms of function and
price. You
>would probably have a 407. Guess what? That ship has tradeoffs
in its
>design, too. Show me an aircraft that doesn't!
(plus other stuff snipped)
Meshnet,
You havn't discussed the main issue I raise, which is the
purposeful reduction in yaw capability of new designs to very
low levels to gain payload. By keeping up the 206 argument, you
blur the real issue, which is the failure to recognize some
threshold level of controllability that would preclude LTE, and
that would preclude the need to blame the pilot for the ensuing
accident.
Nick
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Meshnet
regarding the flight envelope. I do think it is irresponsible to load a Sky
Cam or Cop Copter up to max, as so many are with various mission-specific
equipment, and then fly HOGE through much of a mission. Unfortunately,
operational decisions like this are too often made by employers, with pilots
left to accept such constraints or lose their jobs. On the other hand, as
long as the envelope limitations are adhered to, it can be very useful to
gain payload for a particular mission. Maybe this is a military mindset. I
do agree that new designs should feature adequate tail rotor authority
throughout the normal envelope. I also think that the market has made a
judgment about safety which leaves an opportunity for LTE if a pilot permits
it.
When you and I learned to fly rotorcraft, we did so in machines that simply
had no margin for error. Precision flying and total situational awareness
was required even while doing traffic patterns. Personally, I would go
beyond the tail rotor area in new models and push for designs that are as
forgiving as possible of sloppy, inattentive flying in every way. I don't
understand, for example, why twin engine rotorcraft have to have so much
more pilot workload and confusion that they have a higher accident rate than
singles. I think this is sloppy design. On the legacy machines, including
the ones still being built, I think we need to fly them the way they are
designed to be flown.
Nick Lappos <nlappos...@miami.gdi.net.invalid> wrote in message
Mark W. Roberts
Just wanted to say I saw Nick on TV the other night...with the
Comanche project. He is now...a TV star LOL !!
(just kidding...)
Regards, Mark
nla...@bellsouth.nospam.net
>As I recall, the additional payload comes with appropriate warnings
>regarding the flight envelope. I do think it is irresponsible to load a Sky
>Cam or Cop Copter up to max, as so many are with various mission-specific
>equipment, and then fly HOGE through much of a mission. Unfortunately,
>operational decisions like this are too often made by employers, with pilots
>left to accept such constraints or lose their jobs. On the other hand, as
>long as the envelope limitations are adhered to, it can be very useful to
>gain payload for a particular mission. Maybe this is a military mindset. I
>do agree that new designs should feature adequate tail rotor authority
>throughout the normal envelope. I also think that the market has made a
>judgment about safety which leaves an opportunity for LTE if a pilot permits
>it.
Meshnet,
This is a good exchange, cause I think we both have valid points. While I do
believe that legacy machines are an economic nightmare to modify, the clear
depiction of their limitations, their unique limitations, is warrented so that
the modern buyer can make an intelligent informed choice. I don't agree with
the point of view that all helos have the problem, and that if a pilot
experiences LTE in one of those legacy models that he must have made an error.
The natural upgrade of safety, ease of use, and margins for error is a
necessary requirement of survival in any technical industry. Imagine if our
cars had the survivability of the '60's! crashworthiness, belts airbags,
anti-lock brakes are now the norm. A manufacturer that does not clearly help
us all advance the state of the art holds all of us back!
See this chart to help illustrate my point:
http://personal.mia.bellsouth.net/mia/n/l/nlappos/bell412.jpg
This is taken from Bell's web site, and shows the performance for a Bell 412EP
thay is loaded down until no tail rotor margin is left. That's what the note
about wind from 45 degrees of the nose is all about. This chart is on Bell's
web site today.
It is easy to talk about professionals having training and choices, but I was
first exposed to this chart by a Suadi Colonel, who was using it to plan night
mountain rescue missions! He was given the chart by a salesman, and he asked
me what the note meant. The proposal his country was given by Bell used this
chart to calculate the Search and Rescue mission payload capability. Imagine
pulling into an OGE hover with a helo that is on the pedal stops! One up
collective motion, and we have another pilot error accident!
The point I will continue to make is that there ought to be strict compliance
with modern standards of airworthiness that we can trust, or we will have to
continue to blame the pilot for all those pesky LTE accidents.
Nick
Meshnet
The pilot is responsible for reading and understanding the charts.
Obviously, this chart should not have been used as a proposed basis for
mission planning for an unsuitable mission. Perhaps the theory was that
fuel consumption would resolve the gross weight issue before it became
critical. On the other hand, if I were Bell's lawyer, this sort of thing
would drive me nuts.
You and I aren't going to agree about the question of whether LTE is a
threat in all single main rotor helicopters. I think we agree on most other
aspects of this issue, including that a pilot who allows his helicopter to
get into an unintended right yaw situation is at least partially at fault.
Helicopter design certainly is a factor, though. The current generation of
pilots can't seem to deal with an uncorrelated throttle, either, which was
pretty much second nature to us old farts when we got started. The
limitations that were forced on us by the technology of yesteryear should
not continue to be a problem today, and the market should make its buying
decisions accordingly.
<nla...@bellsouth.nospam.net> wrote in message
<snip>
>
> This is taken from Bell's web site, and shows the performance for a Bell
412EP
> thay is loaded down until no tail rotor margin is left. That's what the
note
> about wind from 45 degrees of the nose is all about. This chart is on
Bell's
> web site today. <Snip> Imagine pulling into an OGE hover with a helo that