Going too fast!

[ATAG_NakedSquirrel]

http://www.youtube.com/watch?v=gnA1Q2JvvJo

Should aircraft break apart in a high-speed dive? I realize the flight manuals have never exceed speeds, but I didn't think ailerons and elevators would start ditching your aircraft when the speed police caught you going too fast.

I understand how a high G load would be able to generate enough force to pull off a wing.

But for control surfaces, I thought air would compress around the leading edge of the wing as an aircraft starts to pick up speed, rendering controls less effective because there is less air-flow over the control surfaces.

The Zero was notorious for this because pilots wouldn't be able to pull out of a high speed dive and they would wind up going full speed into the ground because the controls couldn't re-direct the air flow. The P38 had a similar problem.

One thing that supposedly happens when you approach the speed of sound is that you get a lot of resistance and turbulence, but I'm not sure how this would create a force on control surfaces.

2815
RAF pilot Martindale supposivly dove a Spit XI 975kph IAS (the engine didn't make it, but the control surfaces are intact). The estimated speed is probably off because I doubt the gauge was reading accurately in such a high speed dive.

I've read that the earlier spitfires performed poorly at high speeds because the control surfaces were originally covered in fabric. Later versions were covered in a lightweight alloy, which was much more effective. I've read that the aileron controls in the spitfire also 'reverse' at high speeds, which has something to do with the wing design.

It's hard to get any solid data on high speed diving. Not a lot of pilots were willing to try it for some reason whaa

On a quick side note: Flaps are currently immune to high speed dives. I've tried my best to break/jam flaps in a dive, but it seems they are not included the DM yet. I can't remember if they were during any of the earlier releases or not (doubt it though).

[Kodoss]

Dive limits:

Bf 109 D-1 = 800 km/h TAS
Bf 109 E-1/E-3 = 750 km/h TAS (through heavier weight)

Bf 110 = 700 km/h TAS

Ju 87 = 600 km/h TAS

Ju 88 >> 20° dive below 2000m = 675km/h IAS
Ju 88 >> 20° dive above 2000m = 600km/h IAS
Ju 88 >> 60°/70° Dive with divebrakes = 575 km/h IAS
Ju 88 >> 60°/70° Dive w/o divebrakes = 500 km/h IAS

You can read those values in the historic flight manuals section of our wiki.
Exception is Bf 109 D-1 and Ju 88 A-1 manual, haven't had time to translate and add it.

[Foul Ole Ron]

The high speed damage that might cause bits of your plane such as control surfaces to say cheerio would be due to flutter and critical flutter speed in particular:

http://www.recreationalflying.com/tutorials/groundschool/flutter.html#flutter

[coolhand3011]

http://youtu.be/iTFZNrTYp3k?t=9s
The high speed damage that might cause bits of your plane such as control surfaces to say cheerio would be due to flutter and critical flutter speed in particular:

http://www.recreationalflying.com/tutorials/groundschool/flutter.html#flutter

I would think if this was the case then you'd definitely notice it in the controls and the airframe would be rattling like crazy along with it. One thing I could think of knocking off control surfaces would be excess deflection into the slipstream... but it would be awfully hard given the forces the pilot would have to overcome to get nearly that much deflection. As it is now in the sim, there really isn't a lot of noticeable flutter (maybe FFB users have it?) or shaking beyond the sound that you are approaching max dive speed and then you start shedding parts. Ailerons always seem like the first thing to go, with or without any deflection which seems a little strange at least to me.

I would think compressibility disruption over the control surfaces would be much more likely than shedding parts of a fighter aircraft in a dive. Testing this though in real life like was said before isn't very popular.


http://youtu.be/5ZTK6kEtHag
Flutter Test of a TBF-1 Aileron Installation

[ATAG_NakedSquirrel]

I realize what the flight manuals say. The question is "what happens afterwords?" It it a limit on the engine? IE: the engine will over-rev beyond those speeds. Or does the aircraft tear itself apart.

The only 'hard' evidence I have of aircraft shedding parts is from WW1 aircraft. There were a couple of German and French aircraft that had sesquiplane designs. These are biplanes, but the lower wing is smaller than the upper wing. They made them this way to keep the structural stability of a biplane, and to reduce the extra drag of having a full lower wing.

2820
Sesquiplane Nieuport 11

The lower wing would twist and flutter in high speed dives maneuvers and would snap off. Most monoplanes of the day were fairly vulnerable as well, but that is only because of the materials available at the time.

Biplanes resolved the issue for the most part. The only common problem I know of with biplanes diving at high speeds wasn't so much parts shedding off. It was the fabric buckling and tearing.

2821

Probably due to a similar phenominon that the Mythbusters' duct tape plane had.


http://www.youtube.com/watch?v=pFy5SqY_5tg
Duct tape plane

But those are wood and fabric planes that were barely aerodynamic.

I don't know much about the limits of WW2 aircraft other than the accounts I mentioned before with Japanese Zero's going into uncontrolled dives, quirky/unresponsive behavior at high speeds, and a couple accounts of pilots who managed to pull out after diving insane speeds.

I do think the aircraft would shake like wild if it began to suffer from fluttering, which seems would be the most likely cause of failure.


http://www.youtube.com/watch?NR=1&v=OhwLojNerMU&feature=endscreen
Here's another fun one on fluttering, with music!

[ATAG_NakedSquirrel]

http://www.youtube.com/watch?v=ofz-CDC0Dsg

Another nice one, don't know if the ailerons are functional.

[coolhand3011]

I realize what the flight manuals say. The question is "what happens afterwords?" It it a limit on the engine? IE: the engine will over-rev beyond those speeds. Or does the aircraft tear itself apart.

The only 'hard' evidence I have of aircraft shedding parts is from WW1 aircraft. There were a couple of German and French aircraft that had sesquiplane designs. These are biplanes, but the lower wing is smaller than the upper wing. They made them this way to keep the structural stability of a biplane, and to reduce the extra drag of having a full lower wing.

2820
Sesquiplane Nieuport 11

The lower wing would twist and flutter in high speed dives maneuvers and would snap off. Most monoplanes of the day were fairly vulnerable as well, but that is only because of the materials available at the time.

Biplanes resolved the issue for the most part. The only common problem I know of with biplanes diving at high speeds wasn't so much parts shedding off. It was the fabric buckling and tearing.

2821

Probably due to a similar phenominon that the Mythbusters' duct tape plane had.


http://www.youtube.com/watch?v=pFy5SqY_5tg
Duct tape plane

But those are wood and fabric planes that were barely aerodynamic.

I don't know much about the limits of WW2 aircraft other than the accounts I mentioned before with Japanese Zero's going into uncontrolled dives, quirky/unresponsive behavior at high speeds, and a couple accounts of pilots who managed to pull out after diving insane speeds.

I do think the aircraft would shake like wild if it began to suffer from fluttering, which seems would be the most likely cause of failure.


http://www.youtube.com/watch?NR=1&v=OhwLojNerMU&feature=endscreen
Here's another fun one on fluttering, with music!



Ya that's my thinking too. I know that there are structural limits to the aircraft, even fighters that are built to be quite sturdy to begin with, but it just seems a little strange to recover from a smooth dive that has a mild rumble audibly and to look out at your wings and be missing both ailerons without any shaking or vibrating of the airframe. Maybe something could be put in by team fusion to the effect of fluttering like when you have a busted engine the way the airframe shakes like mad when you start getting to that point. I don't think it's realistic how smooth it is flying and then losing parts of the airframe like that FWIW.

While we are talking about damage, it would also be neat to see if they could incorporate damage to the wings in relation to strength, if the spars and stuff have a hit boxes allocated to them. An example would be that you nailed a guy in the wings and he powered dived to try and escape with 40% spar damage, the wing might fold up early due to the extra stress of the dive on the damaged wing or at least be more prone to failure than one that is 100%. Might see guys with some severe battle damage not take it all the way to the max automatically if the knew that they might want to take it easy on that busted wing instead.

[palker]

Any aircraft will react differently to an overspeed. It depends on many factors and both 1946 and CoD use similar approach of controls surfaces falling of at certain speed and after that wings will fold. It is simple one size fits all solutions but you cannot possibly expect exceeding the never exceed speed without serious consequences. I am fine with what is in the game now as it would be very difficult to figure what exactly would happen to different planes in overspeed.

[Foul Ole Ron]

I realize what the flight manuals say. The question is "what happens afterwords?" It it a limit on the engine? IE: the engine will over-rev beyond those speeds. Or does the aircraft tear itself apart.

If you go past the Vne you can introduce too much stress on the airframe depending on how're maneuvering. Aircraft are only designed to withstand a certain level of stress before getting damaged and then literally breaking apart.



The only 'hard' evidence I have of aircraft shedding parts is from WW1 aircraft. There were a couple of German and French aircraft that had sesquiplane designs. These are biplanes, but the lower wing is smaller than the upper wing. They made them this way to keep the structural stability of a biplane, and to reduce the extra drag of having a full lower wing.

There's a couple of fairly recent examples with P51s in the Reno Races in 1998 and 2011 where elevator trim tab flutter caused the tab to depart from the aircraft. In the first example it resulted in the plane immediately pulling a high g load which blacked the pilot out though he fortunately came around and righted the plane. The 2011 one unfortunately resulted in the pilot's death.

There's a Spitfire accident report where the wing broke off due to aileron flutter though granted the bad weather and gusting winds might have contributed to the airflow problems that caused the flutter to get out of hand:

Tangmere 31 May 1942. "During an interception flight in very bad weather in the Winchester area the pilot of this Spitfire VII was leader of two aircraft. His aircraft was badly damaged in an engagement but he was able to note that the other Spitfire went into a high speed dive. Ground witnesses saw wreckage coming through clouds consisting of fuselage only, both wings being off. The fuselage caught fire after impact and was almost destroyed. The pilot who returned to base thought the other pilot lost control.

"The port wing had broken off at the root bolts and the leading edge rivet seam was sheared from one foot outside the cannon to the outer m/g, indicating high torsion due to aileron flutter. Practically all the structure aft of the spars was broken away. The aileron lever rivets were sheared on the starboard wing. On the port wing, part of the lever comprising the two arms was broken off from its attachment flange and pulled through by the cables to rib 12, where it jammed. Both rear cables are thought to have broken first, ie. those holding the ailerons down.

"The starboard tailplane is thought to have broken upwards, shearing the bolts. The tail end had torn away at the rear joint rivets but was intact. It is considered that structural failure was due to excessive normal loading, produced by an uncontrolled pull out at high speed".

With the Mitsubishi Zero the Japanese had to lower its Vne considerably as flutter could cause the elevator rods to break in a dive and the plane would plummet into the ground

A high speed dive that results in flutter doesn't necessarily result in structural departures though as can be seen in this Spitfire report:

"Spitfire AA912 examined at No 1 CRU for suspected tailplane failure. May 1942. Squadron Leader Craxston said that in the course of a dive to 465 mph violent oscillation of the elevator occurred while pulling out gently. The oscillation was of high frequency and violent enough to throw him about the cockpit and he thought that a tail surface was coming away. He closed the throttle and eased the machine out even more gently, whereupon the oscillations ceased and he was able to make a normal landing. The oscillations lasted a few seconds and he had kept the Spitfire fully trimmed into the dive. There was no abnormal tendency for the elevator control to take charge in coming out of the dive.

I think it's a hard thing to model right in a sim as it's a very complex set of variables to try and take into account. Each plane will react differently and external factors introduce their own variables. Right now the effects of over-speeding in a dive seem fair enough to me when it comes to the early war models. It was something always on the minds of designers during that period and they were introducing various design features to try and overcome the problem. In CLOD you go too fast and you're going to break something but the sim lets you get away without massive structural damage and you can usually get home. Buffeting maybe could be increased in CLOD to give users a better warning but as can be seen in the videos above the onset of vibration can being about massive damage very quickly if speed isn't brought under control.