Apache Crash in Afghanistan (Video)
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Fijdor, and that's how it's done... Ex/current Ag or utility pilot by any chance?
How much does the ol girl lift at that altitude? I'm guessing if you are slinging loads that the 205 would be boned out?
How much does the ol girl lift at that altitude? I'm guessing if you are slinging loads that the 205 would be boned out?
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Utility Pilot, the point was (if the video is real) if you start applying power ahead of time, even a altitude there plenty of space to come out of it.
Higher you are, further ahead of the aircraft you have to be.
I am ready to say that probably 90% of heli pilots have performed that maneuver at one point in their career, some as part of their work, some just for the fun of it and some just to get the blood going once in a while.
JD
Higher you are, further ahead of the aircraft you have to be.
I am ready to say that probably 90% of heli pilots have performed that maneuver at one point in their career, some as part of their work, some just for the fun of it and some just to get the blood going once in a while.
JD
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Epiphany,
Only just seen your comments. Where did anyone, particularly me, criticise Silsoe Sid's flying ability ? I think you'll find no one did, and certainly not me, so stick to the facts mate.
And in terms of amateurism and professionalism it's you that lacks it. You will be hard pushed to find me making comments about anything that demonstrates a lack of either of those characteristics - if having a debate about our opinions is forbidden then what's the point of this forum.
In other threads, Silsoe and I (as well as others) have had a pop at each other but we're all friends now. So you go and make a nice cup of tea and relax
Joel
Only just seen your comments. Where did anyone, particularly me, criticise Silsoe Sid's flying ability ? I think you'll find no one did, and certainly not me, so stick to the facts mate.
And in terms of amateurism and professionalism it's you that lacks it. You will be hard pushed to find me making comments about anything that demonstrates a lack of either of those characteristics - if having a debate about our opinions is forbidden then what's the point of this forum.
In other threads, Silsoe and I (as well as others) have had a pop at each other but we're all friends now. So you go and make a nice cup of tea and relax
Joel
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reduce collective at/near the top of the pull up, i guess they were meaning with full collective, she may not want to turn left. (now which way do those blades go???) American heli, so guessing the same as the Bells and Hughes?
and i would have thought that he had more than full collective up as the ground was rushing up towards him, but then maybe not...
then again they may have meant something completely different...
and i would have thought that he had more than full collective up as the ground was rushing up towards him, but then maybe not...
then again they may have meant something completely different...
Haistofeeck - it is not a bad idea to lower the lever a little on entry because that is where you are loading the disc most - you have high speed, lots of power applied and then you pull back on the cyclic. If you are going to exceed G limits or stress the airframe or reach retreating blade stall, that is one of 2 points in the manoeuvre (the other is the recovery) when that can happen.
From a display point of view it is about aesthetics - if you imagine pulling up to the vertical with a lot of collective still applied, you will be travelling horizontally as you climb. Reducing the collective at this stage reduces that and gives a more vertical climb. However, most wingovers/hammerheads/torque turns don't often get to the vertical.
The recovery, as mentioned earlier, is the second place you have to be careful with the amount of collective you apply - again you have high speed and aft cyclic applied so a lot of collective will increase the G/stress.
A common error is to allow the nose to drop too far and for too long at the apex - this allows the speed to increase rapidly and eats up the available recovery height very quickly.
From a display point of view it is about aesthetics - if you imagine pulling up to the vertical with a lot of collective still applied, you will be travelling horizontally as you climb. Reducing the collective at this stage reduces that and gives a more vertical climb. However, most wingovers/hammerheads/torque turns don't often get to the vertical.
The recovery, as mentioned earlier, is the second place you have to be careful with the amount of collective you apply - again you have high speed and aft cyclic applied so a lot of collective will increase the G/stress.
A common error is to allow the nose to drop too far and for too long at the apex - this allows the speed to increase rapidly and eats up the available recovery height very quickly.
You can see at the beginning of the video on the bottom right side he is marshalling the Apache for the landing, I think what you see beside him is a slingload ready to go and he is calling the Apache in to pick it up.
Lucky him anyway and everybody else as mater of fact.
JD
Lucky him anyway and everybody else as mater of fact.
JD
fijdor: you are kidding, right?
The -10 I have (albeit a few years old) does not show the Apache with a cargo hook.
Is that an option?
RVDT - do please explain your rather dismissive comment.
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Lonewolf, don't know if they have provision for a hook and external load, but it sure look like the guy is marshaling the apache in to him and there is something beside him that looks like a load ready to go.
That's it
JD
That's it
JD
Crab,
I naturally tend to dismiss BS.
If there were limits they would be published.
NickLappos,
Heliport is right, Shawn is the consummate expert!
Having lurked here for a bit, let me weigh in on this pithy subject:
Unlike an airplane, the G's a helo is pulling are only half the story. That is because every helicopter is really two entirely different systems flying in formation - the fuselage, which behaves like an airplane and which we call the "static structure", and the main rotor, which behaves quite strangely under load, and is called the "rotating system".
In turn:
The Static Structure - The G's that the FAR refers to is the load factor experienced by the fuselage - the engine mounts, the tail cone, the feet of the main transmission, and the G meter on the pilot's panel. When the FAR refers to 3.5 g, they refer to the static structure, since the rotor would long prior give up the ghost as the pilot maneuvered that severely.
Frankly, regarding load factor, the FARs were derived from airplane requirements and so they shadow the way airplane behaves. And airplane's structure experiences load factor across the entire aircraft. The wings produce lift and delivered to the whole structure, until the wing stalls or the structure fails. The most extreme maneuver an airplane can successfully perform occurs at the speed where the maximum load factor at stall matches the structural strength of the wings. We call this maneuvering speed and suggest that the pilot slow below maneuvering speed under severe turbulent conditions. Maneuvering speed protects the airplane from structural harm by assuring that the wing will stall before harmful forces are produced. There is no rotorcraft equivalent to maneuvering speed.
The rotating structure – the rotor of a helicopter produces the load factor but virtually no helicopter can produce the load factor required by FAR since virtually no helicopter has a rotor designed for 3 1/2 Gs, except perhaps a very light H-60 or H-64. A rotor designed for 3.5 g at normal weight would consume far too much power in a hover, and require far too much blade chord, again at a cost of considerable payload. The limits to a rotor during high load factor maneuvers are related to the blade stall and the ensuing pitching moment, and the stresses on the pitch links, swashplate and servos. This topic has been much discussed when we've talked about servo transparency, where the blade forces during high load factor maneuvers result in high stresses on the aircraft's controls.
It is safe to say that most helicopters, under limiting rotating system maneuvering, will produce very high blade and control stresses under surprisingly low static system load factors. Because rotor stall is strongly affected by altitude, airspeed, RPM, and collective pitch, it is very hard to predict precisely what load factor would produce excessive rotor stresses. This is why several manufacturers have attempted to employ servo warning limits systems as a means to directly warn the pilot of excess rotating system stresses during maneuvering. The servo limit lights on some EC models and the cruise guide on some Sikorsky models comes to mind.
To give a sense for the kinds of forces the rotor blade can place on the controls and servos here is a thought experiment. Imagine that your helicopter was placed in a hangar and the rotor blade was passed through a hole in the concrete wall and that hole was then bricked up tightly around the blade. Now connect a hydraulic mule to the hydraulic system, bring the system to full pressure and start to move the cyclic around. You can imagine the enormous forces the hydraulic cylinders would impart on the swashplate, pitch links, blade horn, and rotor blades while the rotor blade is trapped in the concrete wall. This condition is precisely what occurs in Jack stall, also called servo transparency except it is the blades that produce the force to drive the hydraulic servos backwards against their maximum force capability.
In a nutshell, load factor is not useful to warn pilots of the damaging maneuvers that the helicopter's rotating system can experience, and in fact a G meter might fool a pilot into thinking his maneuvers were acceptable while the rotor was screaming in protest. Meanwhile, it is very doubtful that the rotor would produce the load factors needed to bother the static system.
As pilots who've experienced Jack stall will tell you, under some conditions, it takes little load factor to create these enormous control system stresses, given some airspeed, altitude and gross weight.
Last edited by NickLappos; 8th Apr 2011 at 07:27.
I naturally tend to dismiss BS.
If there were limits they would be published.
NickLappos,
Heliport is right, Shawn is the consummate expert!
Having lurked here for a bit, let me weigh in on this pithy subject:
Unlike an airplane, the G's a helo is pulling are only half the story. That is because every helicopter is really two entirely different systems flying in formation - the fuselage, which behaves like an airplane and which we call the "static structure", and the main rotor, which behaves quite strangely under load, and is called the "rotating system".
In turn:
The Static Structure - The G's that the FAR refers to is the load factor experienced by the fuselage - the engine mounts, the tail cone, the feet of the main transmission, and the G meter on the pilot's panel. When the FAR refers to 3.5 g, they refer to the static structure, since the rotor would long prior give up the ghost as the pilot maneuvered that severely.
Frankly, regarding load factor, the FARs were derived from airplane requirements and so they shadow the way airplane behaves. And airplane's structure experiences load factor across the entire aircraft. The wings produce lift and delivered to the whole structure, until the wing stalls or the structure fails. The most extreme maneuver an airplane can successfully perform occurs at the speed where the maximum load factor at stall matches the structural strength of the wings. We call this maneuvering speed and suggest that the pilot slow below maneuvering speed under severe turbulent conditions. Maneuvering speed protects the airplane from structural harm by assuring that the wing will stall before harmful forces are produced. There is no rotorcraft equivalent to maneuvering speed.
The rotating structure – the rotor of a helicopter produces the load factor but virtually no helicopter can produce the load factor required by FAR since virtually no helicopter has a rotor designed for 3 1/2 Gs, except perhaps a very light H-60 or H-64. A rotor designed for 3.5 g at normal weight would consume far too much power in a hover, and require far too much blade chord, again at a cost of considerable payload. The limits to a rotor during high load factor maneuvers are related to the blade stall and the ensuing pitching moment, and the stresses on the pitch links, swashplate and servos. This topic has been much discussed when we've talked about servo transparency, where the blade forces during high load factor maneuvers result in high stresses on the aircraft's controls.
It is safe to say that most helicopters, under limiting rotating system maneuvering, will produce very high blade and control stresses under surprisingly low static system load factors. Because rotor stall is strongly affected by altitude, airspeed, RPM, and collective pitch, it is very hard to predict precisely what load factor would produce excessive rotor stresses. This is why several manufacturers have attempted to employ servo warning limits systems as a means to directly warn the pilot of excess rotating system stresses during maneuvering. The servo limit lights on some EC models and the cruise guide on some Sikorsky models comes to mind.
To give a sense for the kinds of forces the rotor blade can place on the controls and servos here is a thought experiment. Imagine that your helicopter was placed in a hangar and the rotor blade was passed through a hole in the concrete wall and that hole was then bricked up tightly around the blade. Now connect a hydraulic mule to the hydraulic system, bring the system to full pressure and start to move the cyclic around. You can imagine the enormous forces the hydraulic cylinders would impart on the swashplate, pitch links, blade horn, and rotor blades while the rotor blade is trapped in the concrete wall. This condition is precisely what occurs in Jack stall, also called servo transparency except it is the blades that produce the force to drive the hydraulic servos backwards against their maximum force capability.
In a nutshell, load factor is not useful to warn pilots of the damaging maneuvers that the helicopter's rotating system can experience, and in fact a G meter might fool a pilot into thinking his maneuvers were acceptable while the rotor was screaming in protest. Meanwhile, it is very doubtful that the rotor would produce the load factors needed to bother the static system.
As pilots who've experienced Jack stall will tell you, under some conditions, it takes little load factor to create these enormous control system stresses, given some airspeed, altitude and gross weight.
Last edited by NickLappos; 8th Apr 2011 at 07:27.
fijdor, if what you are seeing is a prepared load, perhaps they had set that pile of stuff up for a UTILITY helicopter to come and pick up, at some point that day. That would be unrelated to the fellow in the ATTACK helicopter showing up to demonstrate his "not quite excellent" maneuver.
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The maneuver obviously should not have been attempted however after looking at the video several times in my opinion the nose was left down too long. A very high ROD and recovery was too low. On the way down he could have recovered if the recovery was initiated earlier. At that point he could have relaxed at the bottom and made the maneuver look good. But like I said it should not have happened in the 1st place.
RVDT - whilst acknowledging Nick's expertise - he has not given all of the story.
I instructed on the Gazelle for many years and demonstrated steep turns and jackstall on many occasions - the 60 degree AoB steep turn we taught is by definition a 2G manoeuvre and the Gazelle had no problem with them at all.
We became accustomed to the feel of 2 G in a helicopter but had to exceed this by some margin in order to get to jackstall in a turn - this was one of 2 ways jackstall was demonstrated, the other was in a dive to VL (circa 168 kts) and then pull aft cyclic.
Although the G loading was less in the dive and pull manoeuvre, the stress on the controls was the same as pulling between 2.5 and 3 G in a lower speed, high AoB turn as proved by the onset of jackstall or servo transparency.
So in 2 different manoeuvres, although the jackstall prevented (theoretically) damage to the control system, the turning manoeuvre produced a much higher load on the airframe.
We (the UK Mil) were eventually stopped from demonstrating jackstall so frequently due to the damage we were doing both to the controls and the fuselage (especially the tail boom). As any aircraft designer will tell you it is not just the load factor which is important but the number of cycles of that load factor which fatigues the airframe.
I also had the privilege of instructing on the Lynx which is a very capable aerobatic helicopter - most of ours were fitted with G meters because they were used by the Blue Eagles display Team.
Westlands kitted out a Lynx with accelerometers and flew the various manoeuvres to determine the loads on various parts on the airframe - both the static and the rotating elements - and each manoeuvre came with a servicing penalty which reduced hours on the various components - particularly the TR assembly.
The G limit was 2.5 for all manoeuvres but I saw in excess of 3 G when some manoeuvres were not smoothly flown - the back flip from hover to hover was especially difficult to do inside the limits.
Flying with a G meter makes you very sensitive to aft cyclic application, both rate and displacement and the pull up to a wingover could very quickly exceed 2G if the pilot was a bit ham-fisted.
So my points are - you can generate enough G to stress both the airframe and the controls without reaching a limiting factor like jackstall or RBS.
If you don't think extra G is an issue - would you load your helo up to twice its MAUM and fly it? It's the same thing and just because there are no published limits doesn't mean it is good for the helicopter.
I instructed on the Gazelle for many years and demonstrated steep turns and jackstall on many occasions - the 60 degree AoB steep turn we taught is by definition a 2G manoeuvre and the Gazelle had no problem with them at all.
We became accustomed to the feel of 2 G in a helicopter but had to exceed this by some margin in order to get to jackstall in a turn - this was one of 2 ways jackstall was demonstrated, the other was in a dive to VL (circa 168 kts) and then pull aft cyclic.
Although the G loading was less in the dive and pull manoeuvre, the stress on the controls was the same as pulling between 2.5 and 3 G in a lower speed, high AoB turn as proved by the onset of jackstall or servo transparency.
So in 2 different manoeuvres, although the jackstall prevented (theoretically) damage to the control system, the turning manoeuvre produced a much higher load on the airframe.
We (the UK Mil) were eventually stopped from demonstrating jackstall so frequently due to the damage we were doing both to the controls and the fuselage (especially the tail boom). As any aircraft designer will tell you it is not just the load factor which is important but the number of cycles of that load factor which fatigues the airframe.
I also had the privilege of instructing on the Lynx which is a very capable aerobatic helicopter - most of ours were fitted with G meters because they were used by the Blue Eagles display Team.
Westlands kitted out a Lynx with accelerometers and flew the various manoeuvres to determine the loads on various parts on the airframe - both the static and the rotating elements - and each manoeuvre came with a servicing penalty which reduced hours on the various components - particularly the TR assembly.
The G limit was 2.5 for all manoeuvres but I saw in excess of 3 G when some manoeuvres were not smoothly flown - the back flip from hover to hover was especially difficult to do inside the limits.
Flying with a G meter makes you very sensitive to aft cyclic application, both rate and displacement and the pull up to a wingover could very quickly exceed 2G if the pilot was a bit ham-fisted.
So my points are - you can generate enough G to stress both the airframe and the controls without reaching a limiting factor like jackstall or RBS.
If you don't think extra G is an issue - would you load your helo up to twice its MAUM and fly it? It's the same thing and just because there are no published limits doesn't mean it is good for the helicopter.
RVDT,
I don't think Nick's well written piece supports your argument at all - quite the contrary!
Summed up nicely in this extract:
The point being that you don't actually know what damage you are doing.
I don't think Nick's well written piece supports your argument at all - quite the contrary!
Summed up nicely in this extract:
It is safe to say that most helicopters, under limiting rotating system maneuvering, will produce very high blade and control stresses under surprisingly low static system load factors
Westlands kitted out a Lynx with accelerometers and flew the various manoeuvres to determine the loads on various parts on the airframe - both the static and the rotating elements - and each manoeuvre came with a servicing penalty which reduced hours on the various components - particularly the TR assembly.
Does that not confirm exactly what Nick said?
Flying with a G meter makes you very sensitive to aft cyclic application, both rate and displacement and the pull up to a wingover could very quickly exceed 2G if the pilot was a bit ham-fisted.
You must have gone through a lot of colored pencils on those routines.
212 man - my point was that you can generate high static loads in manoeuvres without the 'protective' engineering
warning you.
Nick's article highlights that low static manoeuvres can stress the control runs and blades. I think the two points are complementary.
Sas - the point about sensitivity was that without a G meter telling you what you are pulling it is very easy (unless you experience vibration/RBS/jackstall) to think you are flying smoothly and modern semi-rigid rotor systems have a lot of control power that can generate high rates of pitch and roll very quickly.
This is why several manufacturers have attempted to employ servo warning limits systems as a means to directly warn the pilot of excess rotating system stresses during maneuvering. The servo limit lights on some EC models and the cruise guide on some Sikorsky models comes to mind.
Nick's article highlights that low static manoeuvres can stress the control runs and blades. I think the two points are complementary.
Sas - the point about sensitivity was that without a G meter telling you what you are pulling it is very easy (unless you experience vibration/RBS/jackstall) to think you are flying smoothly and modern semi-rigid rotor systems have a lot of control power that can generate high rates of pitch and roll very quickly.