Aces High Bulletin Board
General Forums => Aces High General Discussion => Topic started by: TeeArr on February 23, 2013, 07:48:30 PM
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Since when did the Hurricane shed flight control surfaces in a dive? It has happened to me three times, all of them with engine at Idle and at a 45 degree angle or less. There were no inputs to my control surfaces...they just departed the aircraft. Is the Hurricane only meant to be used as a low level defensive gamepiece?
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Neither the angle at which you dive nor your throttle setting matter, if you were going over the Hurricanes maximum speed, it will lose parts.
Also, the Hurricane was exactly that in WWII, to defend Britain, not to attack germany (generally)
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Thought you were gone from the game. :noid
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Since when did the Hurricane shed flight control surfaces in a dive?
Since it was remodeled :)
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Hurri I had canvass control surfaces, yes? What about Hurri IIx and Sea Hurricane?
I can see how the Hurricane frame would not take the extreme stress, it was an older airframe and meant for air to air combat and that usually did not consist if high speeds. There is a reason that during the 1930's and early 1940's the fighters were only fighters and were not used interchangeably with dive bombing: the fighters couldn't handle the stress.
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canvas covered flight surfaces often reduced control effectiveness at high speeds...
They didn't pop off!
IMO HTC is taking this the wrong way when they do that. Make them react less, make them lock up, make them compress, but to have them "pop off" is utter nonsense and shouldn't be put in the game like that.
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I've read where hurris lost control surfaces in dives... aluminum rudder, and such..
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I've read where hurris lost control surfaces in dives... aluminum rudder, and such..
Got any kind of reference or link for that?
There are stories of planes diving so fast they wrinkle the metal on the wings and shred the gearbox behind the prop blades, but they don't lose control surfaces. The fact that the controls were fabric covered doesn't mean they were wrapped in cotton T-shirts. It was a tough material stretched very taught, doped to string it tight as possible. The frame underneath was strong. What happened was the surface tension of the skin was overcome by the airflow over it, and they would flap, or ripple, at extreme speeds.
If a hurricane lost the control surface in a dive, it means the entire thing was weakened, down to the hinges and the frame underneath. I find that unlikely. Even in the most extreme I'd expect only to have the fabric lose effectiveness (not give you the flight control input you want) as it sags under pressure, or to simply rip the material.
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canvas covered flight surfaces often reduced control effectiveness at high speeds...
They didn't pop off!
IMO HTC is taking this the wrong way when they do that. Make them react less, make them lock up, make them compress, but to have them "pop off" is utter nonsense and shouldn't be put in the game like that.
Have you never heard of flutter? Flight control surfaces most definently will depart an aircraft if high-speed results in flutter. Remember Jimmy Leeward's P-51 at Reno last year? Flutter. I have no evidence that the Hurricane ever experienced it but I see no reason it wouldn't be as susceptable as any other aircraft.
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Apples and Oranges.
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Apples and Oranges.
Apples and apples. The Hurricane dives to fast, has flutter, looses control surfaces. There are no Oranges here.
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Not even. Leeward's P-51 didn't lose control surfaces. They used bad locknuts on his trimtab.
Flutter is one thing. Flutter is vibrations oscillating back and forth. What happened to Leeward wasn't "flutter" ... It was sudden loss of trim which caused massive Gs.
I've read it elsewhere, when the crash just happened, but first google result that comes up is wiki so here's the copy and paste:
The NTSB thoroughly investigated the extensive modifications made to the airplane. The modifications had made the aircraft lighter and reduced drag, but decreased stability. Leeward took the plane to 530 mph during the race, about 40 mph faster than he had ever gone before.[24] There was evidence of extreme stress on the airframe demonstrated by buckling of the fuselage aft of the wing and gaps appearing between the fuselage and the canopy during flight (clearly visible in high resolution photographs taken by spectators). However, the investigation (released in August 2012) found that probable cause of the crash was old reused locknuts in the left elevator trim tab system that loosened. This led to a fatigue crack in an attachment screw and allowed the trim tab to flutter. This flutter caused the trim tab link assembly to fail which led to loss of control of the aircraft. Untested and undocumented modifications to the airplane contributed to the accident. Particularly, the right trim tab had been fixed in place. Had both trim tabs been operational, the loss of the left trim tab may not have alone caused loss of control. When the trim tab failed, Leeward was exposed to 17Gs which quickly incapacitated him and likely rendered him unconscious.
EDIT: P.S. There's a MASSIVE difference between trim tabs and their attachment points vs the entire control surface.
Just so you're not confusing one for the other, this is a trim tab:
(http://i.imgur.com/qisNW.jpg)
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Not even. Leeward's P-51 didn't lose control surfaces. They used bad locknuts on his trimtab.
Flutter is one thing. Flutter is vibrations oscillating back and forth. What happened to Leeward wasn't "flutter" ... It was sudden loss of trim which caused massive Gs.
I've read it elsewhere, when the crash just happened, but first google result that comes up is wiki so here's the copy and paste:
EDIT: P.S. There's a MASSIVE difference between trim tabs and their attachment points vs the entire control surface.
Just so you're not confusing one for the other, this is a trim tab:
(http://i.imgur.com/qisNW.jpg)
Well, thanks for the lecture and pretty picture Krusty but I think I know a little bit about airplanes and you are still wrong. Here's the part of your own quote that you seem to have missed:
This led to a fatigue crack in an attachment screw and allowed the trim tab to flutter. This flutter caused the trim tab link assembly to fail which led to loss of control of the aircraft
The P-51 was lost due to flutter. It's not a debatable subject, it's a simple fact. The proximate cause of the mishap was old locknuts but the failure mode was flutter just as the quote you provided says. Something like old locknuts may seem a surprising cause of flutter but even things as simple and varied as worn out bushings or even too much paint buildup can cause it. Causes also include lots of other stuff like incorrectly rigged, weighted, or balanced control surfaces all the way up to insufficient structural rigidity and damping leading to aeroelastic motions of an entire wing surface. Flutter is an extremely dangerous aerodynamic factor that has been known for a long, long time and it can, and has, lead to catastrophic failure. The faster you are the more likely it is you'll excite flutter and more damage will be done because of the greatly increased amounts of energy available. In the P-51's case the trim tab was loose and began to flutter causing it to fail which resulted in loss of control due to untrimmed aerodynamic loads on the horizontal elevator at high speed.
The fact that it was a the trim tab that failed due to flutter and not the entire elevator in this case is irrelevant. It's a great example of how the failure of even a small part can cause a catastrophic outcome but entire control surfaces, stabilizers, tails and even wings can be lost and because flutter is directly related to speed it's one of the primary limitations that can define an aircraft's Never Exceed Speed (Vne), in other words, your dive speed. When I was at Pax River a friend of mine was doing the flight tests on the Navy's new E-6 (known as Looking Glass) which was a militarized version of the Boeing 707. During the tests they did a Vne test by diving the plane and in spite of all the engineering analysis, careful test planning for safety, and instrumentation specifically designed to detect flutter before it could do any damage they lost the entire rudder. There is absolutely zero doubt that flutter during a high-speed dive can cause the loss of a control surface. I won't even caveat that statement with "in my opinion" because it's a simple, established, and well known fact. It's such a well known fact that every airplane built has to go through flutter testing because of the danger. The probability that a Hurricane would experience flutter in a high speed dive beyond Vne leading to catastrophic failure is right at 100%. What part that would fail is harder to say, it could be ailerons, rudder or even an entire stabilizer or wing but having the elevators fail is perfectly reasonable.
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Just so you're not confusing one for the other, this is a trim tab:
Yes Mace, pay attention! Do you even know the difference between a wing and a wingnut? :old:
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In Ira Jones book Tiger Squadron, he refers to Hurri 1's routinely diving to 500mph and Spit 1's exceeding 550. He doesnt mention bits dropping off. :headscratch:
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hurri 2 d wing popped off when I was a little eager beaver to pop a tank turret. or rather prevent an issue with the accelerating ground mass.
Just have to be smooth and not yank the stick with excess energy.
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I'm not climbing into the discussion over 'flutter' and wingnuts though it highlights the amazing piece of engineering that these planes are that something so simple as an improper wingnut could cause a plane to crash. 12 months prior to any of these amazing birds rolling off an assembly line they were nothing more than piles of ore freshly dug out of the ground.
Amazing human creations!
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In Ira Jones book Tiger Squadron, he refers to Hurri 1's routinely diving to 500mph and Spit 1's exceeding 550. He doesnt mention bits dropping off. :headscratch:
He doesn't then mention them going to 550 and 600 respectively, correct? The numbers he quotes might be the numbers because pilots don't like suicide and to go above those numbers would result in bits dropping off or maybe it's just because a few people that did it and survived told their story while the guys that didn't survive, well, didn't. If someone wants to make the argument that the speeds at which failures occur in AH are too low then that's fine, I have no proof or documentation about either of these aircraft regarding what their specified red-line speeds (sometimes called placarded limits) were and even if we did, the red-line speed isn't a "wall." Any posted limit has some safety margin built in so it's quite possible, and in war time probable, that many of these limits were routinely violated. If you know you're going to die are you really going to worry about a placarded limit whether it be speed, G or engine power? Be kinda dumb to die by being shot out of the air but being on the "right" side of limits.
Also, assuming these speeds are above redline (and, like I said, that's a comfortable assumption) you have to conclude that at least some were successful it doing so to the speeds you mention but then you're not going to hear much from the guys that were unsuccessful. Of the ones that were unsuccessful, I don't know if they were unsuccessful because of flutter or loss of control or over-G while trying to pull out, or they blew their engines up by overspeeding them up but the probability of something bad happening goes way up the faster you go. For a sim like AH, I don't know what the flight model uses for red line but I'd guess that there is some documented evidence of what the placarded limit was to establish it. Maybe in the new Hurricane model it's too low, or, maybe the new model is based on better info than originally used. I don't know what info HTC has but anecdotal evidence is difficult to use as established "fact" because, as I mentioned, you only hear from the guys that did it and survived and also there is the fact that exaggeration is not unknown in the fighter community.
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The one that doesn't make sense to me is the Mossie VI and Mossie XVI. They have the same wing (the improved, stronger wing was introduced with the Mk VI) and tail, but the Mk VI loses control surfaces and the Mk XVI doesn't.
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I'm not climbing into the discussion over 'flutter' and wingnuts
Actually I was implying Krusty was the wingnut. :old:
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I'm not climbing into the discussion over 'flutter' and wingnuts though it highlights the amazing piece of engineering that these planes are that something so simple as an improper wingnut could cause a plane to crash. 12 months prior to any of these amazing birds rolling off an assembly line they were nothing more than piles of ore freshly dug out of the ground.
Amazing human creations!
These forums need a '+' or a '-' feature... then watch out.. these technical discussions will turn into the 'WWE'..
But yes that why I have loved planes from as far back as I can remember..
W-W
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The Krusty's are strong in this thread.
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I cant vouch for the merits in which HTC chooses if and when control surfaces bust off, but I too think it seems a bit odd that some aircraft are so fragile. The Hurricanes are one of them. I still think that canvass control surfaces would not able able to handle the same stress as metal control surfaces, but like most others here I have no proof and am only speculating.
I know when I see debates about the abilities of the P38, I just open up "Fork Tailed Devil: The P38", by Martin Caidin. While it doesn't have all of the exact specifics, having testimony from the pilots who flew it in combat AND hard stats to reference means something. If there are similar books out there on the Hurricane I would hope HTC would reference them as well and if there are multiple Hurricane pilots performing X maneuver and Y speed, and there are RAF operations manuals (pilot guides, etc), saying it preferred or OK to perform X maneuver up to Y speed, etc, then lets hope HTC models it in their AH Hurricane. Even with all the advanced flight modeling programming available, some things need to addressed outside of whatever the software says it "needs" to be. If the Hurricane was able to safely dive and Y speed and do it repeatedly in the real deal, then lets hope HTC will at least review their programming.
Same goes for the B25. I don't think there is a plane in AH that has as feeble elevators and ailerons as the B25.
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The Hurricane mkII is very good :old:
Bits only fall off it if you don't fly it properly :old:
I really like the seconds finger on the clock :old:
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I have been playing this game for approximately 12 years. Never have I had a Hurricane, in a controlled dive; (Throttle Idle, control surfaces neutral, 320 KIAS) had control surfaces depart the aircraft. I have had an aircraft shed it's main planes (wings) during an aggressive dive recovery, but never until the past few weeks had a Hurricane jettison it's control surfaces. The first two times it was just the elevators, the first time I was almost able to land after recovering from the dive. The second time I augured. The third time, I watched as (in this order) the ailerons departed simultaneously, followed quickly by the elevators both simultaneously, and then the rudder. Snap!...Snap!, snap! From everything I have read about the Hurri, it was an extremely strong bird with it's massively wooden stringer ed empanage. It wasn't a fast aircraft, but even 400 - 450KIAS is not an unreasonable speed or stress for that plane to handle.
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Shida, go back to hiding under your rock. It's where you belong.
Mace, no. There's a massive difference between "flutter" lossening locknuts which were old and should not have been used in the first place, to losing the entire flight surface.
The flight controls had LARGE mounting points. Large pins fited into the ribs of the flight surfaces (wings, tail, stabs, etc). There are reports that even when shot away and with the control surface fluttering wildly, planes have made it back safely. One Flying Tiger P-40 escorting B-24s was set upon by a Ki-43. It shredded his rudder control links, and the rudder, and the entire thing was flapping back and forth violently as he withstood a heavy onslaught of enemy fire. After being cleared by a wingman he flew home, rudder fluttering back and forth the entire time. He made it back perfectly safe.
You're trying to imply flutter is lethal, when it is not. Flutter causes a flight surface to flip up and down rapidly. When the surface is fixed in place, these translate into vibrations along the mounting points and the control arms or cables. It makes it harder for a pilot to hold the stick steady, for example. In Leeward's case, the flutter on the trim tab induced vibrations into the control arm, which became detached because of poor maintenance on the point of attachment. Once detached, the trim tab flapped up and down wildly (like a limp flag being whipped back and forth in a massive wind). The trim tab then failed, because it is only held onto the elevator by a handful of screws.
What brought down Leeward's P-51 wasn't the flutter on the trim tab. He had nose-down trim apparently to keep himself in his very high speed dive. To ease stick pressure the trim tab was deflecting the elevator down. As soon as the trim pressure was gone, the pressure of the airflow over the elevator slammed it back to "neutral" trim instantly. This was like jamming the stick back with hundreds of pounds of stick force in a split second. Leeward experienced 17Gs of pressure and blacked out instantly also.
Meanwhile flutter was only what removed a poorly maintained trimtab that lost its control arm. Had that control arm been properly in place, the tab and the elevator and ALL control surfaces would still have encountered flutter. It would have been inconsequential.
Don't confuse that with your mythical link between flutter and ripping off entire control surfaces in aces high. Flutter is there, but control surfaces are strong enough to survive with it.
P.S. The force of the pitch-up On Leeward was so bad that it bent the plane's frame behind the wing trailing edge attachment point.
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Krusty you do know that Mace is a former F-14 fighter jock and test pilot, right? Just wanted to give you a heads up before you make yourself look even more silly.
ack-ack
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Krusty you do know that Mace is a former F-14 fighter jock and test pilot, right? Just wanted to give you a heads up before you make yourself look even more silly.
ack-ack
Don't stop him now :banana:
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Matt Garth didn't survive flutter at the end of Midway trying to land on the Enterprise...
:bolt:
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Thanks Ack-Ack, I was aware. His direct equation of flutter effect to ripping control surfaces off of HTCs variant of the Hurricane is so far off as to show he's making a poor joke or doesn't know much about WW2 aircraft. He may be a great F-14 pilot, and I won't dare impugne his service, but from his comments he doesn't know much about WW2 aerodynamics.
I was honestly trying to enlighten him, and not to pick on him (if that was the feeling).
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Are we talking about actual damage sustained from over-speeding an aircraft? Or the damage model that our game is capable of to discourage such behavior?
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Mk84, it isn't just to "discourage behavior" -- instead it is wrongly implemented and historically inaccurate. We, however, were comparing real world to what AH has modeled. More likely an attempt to create an arbitrary "weakness" to a plane.
By the way, let's just get one thing straight here. I know flutter is an all-encompassing thing. All parts of a plane, building, bridge, or even telephone pole can experience violent flutter.
This topic is specific to the control surfaces themselves. Most combat fighter aircraft have proven they are strong enough to withstand metal-shattering levels of flutter*. Mace saying the flutter ripped off the elevators and ailerons is absurdly. Such an amount of flutter would shatter the entire airframe along with the control surfaces. Yet we have almost EVERY test flight in the history of WW2 aircraft to show us that flutter didn't do such things. Hence his claim that flutter rips control surfaces off of WW2 aircraft in dives is wrong.
*= poor phrasing, but meant to suggest weaker commercial or civilian planes would not withstand it.
P.S. Flutter is most definitely not limited to clotch-covered control surfaces. It has little to do with whether they are metal covered or fabric.
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Krusty, I'll try and look up where I read that, I've read a ton of material so it may take some time... but I definitely remember reading where the hurri, TA152, C202, and seems like the early yak had aileron failures in dives.... sorry for not having the source on hand...
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You're trying to imply flutter is lethal, when it is not. Flutter causes a flight surface to flip up and down rapidly. When the surface is fixed in place, these translate into vibrations along the mounting points and the control arms or cables. It makes it harder for a pilot to hold the stick steady, for example. In Leeward's case, the flutter on the trim tab induced vibrations into the control arm, which became detached because of poor maintenance on the point of attachment. Once detached, the trim tab flapped up and down wildly (like a limp flag being whipped back and forth in a massive wind). The trim tab then failed, because it is only held onto the elevator by a handful of screws.
Actually there are plenty of cases where control surfaces have been lost due to flutter and cases where the wings/airframes have come apart due to it.
For example, flutter became a problem during the development of VL Myrsky fighter. On November 19th 1943 MY-3 and test pilot Siltavuori were lost due to brake up of stabilizers and wings in high speed dive due to flutter. During diving tests on 23.6.1944 left elevator half departed from MY-6 due to flutter.
Source: Lentäjän Näkökulma I
You truly aren't understanding how much force is involved when air is moving around the control surface at speeds over 500mph. You need to actually read about the phenomenon before talking about it.
Examples of flutter: http://youtu.be/qpJBvQXQC2M (http://youtu.be/qpJBvQXQC2M)
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Thanks Ack-Ack, I was aware. His direct equation of flutter effect to ripping control surfaces off of HTCs variant of the Hurricane is so far off as to show he's making a poor joke or doesn't know much about WW2 aircraft. He may be a great F-14 pilot, and I won't dare impugne his service, but from his comments he doesn't know much about WW2 aerodynamics.
I was honestly trying to enlighten him, and not to pick on him (if that was the feeling).
Well, well, aren't we just a bit full of ourselves? :rofl I've tried to be reasonable about this and explain the facts but you're really the proverbial horse who won't drink the water. What makes this really interesting is that you seem to be suffering from the delusion that you're doing the leading. I suggest you take a drink before you faint Mr Ed! :lol
Let me quote the most illuminating comment you've made:
You imply flutter is lethal, which it is not
Maybe I'm just not being clear. I'm not "implying" a thing, I'm stating flat out that flutter is lethal and a perfectly reasonable failure mode for HTC to emulate in their flight model. I've also said I have no idea if the speeds this occurs at in AH are correct or if it's an established fact that the Hurricane's elevators came off, I've simply said that it's a fact that parts, including elevators and even wings can come off of any plane due to flutter therefore it's reasonable to model such issues in the game. You, by the same token, cannot seriously argue that these failures never occured in Hurricanes as, if they did, there would be few pilots actually available to write a report about it. You can debate all you want about whether a particular surface or another will fail but the simple fact is this exists, it's not "inconsequential" or a "myth" as you claim. Flight control surfaces, stabilizers, and even wings have come off so what real difference does it make to argue that it's impossible for an elevator to come off, especially where you have no facts to back up that assertion?
But you say flutter can’t do this anyway. Your one example of a P-40 is missing a key fact that I've explained before (and you seem to just ignore) that the amount of damage done by flutter is directly related to the speed at which it occurs. This also is the reason that flutter, in a dive at excessive speeds, is extremely damaging. F=MA and all that. You have no idea what speed the P-40 was at but it's obvious he was below the speed at which enough energy would be added to the flutter to cause failure. I’ll bet his return was as slow as possible and scary as all get out but if he dove the airplane in that condition he would, with absolute certainty, eventually reach a speed in which the rudder or tail would have failed. You also ignore the fact that you're relying on the reports of survivors, what about those that couldn't write one? I even gave you an example of the loss of a flight control of which I have direct personal knowledge but you're being kinda ignoring that.
Maybe you'll believe Georgia Tech:
The first recorded and documented case of flutter in an aircraft occurred in 1916. The Handley Page O/400 bomber experienced violent tail oscillations...The incident involved a dynamic twisting of the fuselage to as much as 45 degrees in conjunction with an antisymmetric flapping of the elevators. Catastrophic failure due to aircraft flutter became a major design concern during the First World War and remain so today."
http://catdir.loc.gov/catdir/samples/cam031/2001052552.pdf
Maybe you'll believe NASA: The pilot in this is Fred Haise who was later the Lunar Lander Pilot on Apollo 13 and did the flutter testing for the Space Shuttle while flying Enterprise. The test was stopped before the plane lost its horizontal tail but after the flight Haise said "I'm fearless but that scares me." http://www.youtube.com/watch?feature=player_detailpage&v=pEOmCkZyXzk&list=SPCCF3D4E62537914E
Remember that you said flutter can't rip off elevators and ailerons, that it's "absurd"? Or that "most combat fighter aircraft have proven they are strong enough to withstand metal-shattering levels of flutter?" How about "flutter is there, but control surfaces are strong enough to survive with it?" So, at the beginning you said flutter was little more than a vibration (I’d guess Haise would disagree) and you still deny that it's powerful enough to rip off elevators and ailerons, and that fighters (and their control surfaces) are too strong to be affected. These are nothing more than blanket statements of unsupported opinion masquerading as facts. Let’s check out an example to see how your "facts" stand up in the real world. Here's a perfect video example of just how powerful flutter forces can be. http://www.bing.com/videos/search?q=f-117+crash+maryland&view=detail&mid=2BE0018CE1CE944C4D252BE0018CE1CE944C4D25&first=0&FORM=NVPFVR (http://www.bing.com/videos/search?q=f-117+crash+maryland&view=detail&mid=2BE0018CE1CE944C4D252BE0018CE1CE944C4D25&first=0&FORM=NVPFVR)
Maybe, just maybe, you'll consider what I said rather than being simply argumentative.
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I'd say that pretty well covered it, Mace.
Here's a link to how flutter affected the X15's tail surface and how far they had to go to overcome the disastrous results of it.
http://youtube.com/watch?v=aZdMTfKeIoQ
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Most planes have a Vne... Velocity (never exceed)... this is discovered by test pilots before the combat pilots get the planes. Bad things happen when reaching 'never exceed' speed.
Be glad that the whole plane doesnt just shatter and/or including the canopy, so all we have left is the chute.
Guessing that Vne for the pilot would be less than for the plane?
Maybe each plane should show this value on the speedometer - red shaded area? Wish list stuff?
What do the handbooks say about Vne? Might as well note Vcompression while were at it?
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Pilot's Notes for Hurricane IIa/IIb/IIc/IId/IV give a Vne of 390mph IAS.
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strong enough to withstand metal-shattering levels of flutter*.
Metal-shattering, wowsers. I wish I had a copy of the Marvel Comic Book of Metallurgy.
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In a book called "set guns to fire" a hurricane wing commander and BoB ace says they often went over 450mph in a dive to evade 109's you just had to be careful. One pilot is 6 squadron (my grand fathers squadron) was credited with a "kill" when he entered a dive with a 109 behind . he got up to 420mph pulled back hard and heard a very loud "crack". the next thing was laughter and cheers from his wingman who told him the 109 that was chasing him folded up trying to follow him out of the dive . My grand dad spent 12 hours trying to fix that hurricane . there was a crack running down the width of the wing where it joins the fuselage next to the wing tanks . he flew back with held together pretty much just by the control wires . when he did land the wing was level instead of an upward dihedral. wooden wings were thought of as stronger by the ground crews as they had less issues in a dive .