Did the Me 262 break the sound barrier?

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Topspeed
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#31

Post by Topspeed » 24 Jun 2004, 09:44

GP,

The negative elevator force is due to the fact that every plane has some incident in the wing..since the plane travels near the speed of sound..it wouldn't need the liftforce of the wing that much anymore..that is why they had to compensate it with a push of the controlcolumn.

See the faster the kite goes the more you gotta push.

JT

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#32

Post by Hop » 26 Jun 2004, 23:51

If they were able to reach .89 with Spitfire XI then I would almost certainly say it was possible to dive to mach 1.001 with a Swalbe.
Don't look at the Spitfire, which like all WW2 fighters fell far short of mach 1.

Compare to the prototype F-86 Sabre, which was marginally supersonic in the dive (mach 1.02)

The Sabre had much lower normal drag than the 262, with a 5000 lbs thrust engine it did 650 mph, with 4000 lbs the 262 did 540. So normal drag was much lower on the F-86, and the weight was similar (iirc). That gives the F-86 a huge advantage to begin with, but the F-86 was also much better when approaching the sound barrier.

The F-86 had thinner wings than the 262, it had a lower aspect ratio than the 262, and it had heavily swept wings.

If you look at the first graph I posted in this thread, you can see the dramatic rise in drag factor (actual drag will be increasing even faster than this) as you exceed critical mach.

The Spitfire does well in that test because it had thinner wings than the others, and slightly lower aspect ratio. That gave it a higher critical mach, which means the dramatic rise in drag is delayed to higher speeds.

The F-86 has a much higher critical mach than the 262, as well as lower drag to start with. There'd be much, much more difference between the F-86 and 262 on that graph than there is between the Spitfire, Mustang and Thunderbolt. And the F-86 prototype only just passed mach 1.
Spitfire was designed already in the thirdies and even a Fiat G.50 did reach the speed of 850 km/h the engineers were somehow able to calculate it already back then.
Note the speed the Spitfire reached in that dive, 609 mph, that's 981 km/h
BTW: Tempest was able to dive at 540 mph roughly mach 0.75 ( 870 km/h ) safely according to manual and thence close in on a Me 262 for instance.
Yes, the Tempest was one of the fastest divers of the war, acording to the AFDU, a British test establishment that evaluated British, allied and enemy aircraft, the Tempest had " the best acceleration in the dive yet seen at this Unit."

That's dive acceleration, though, which the Spit didn't excel in. What the Spitfire exceled in was maximum dive speed. According to the manual, the safe diving limit was limited to mach 0.85, which is higher than any other prop fighter, and higher than most of them were tested at.
PS: Didn't they loose a prop at such an attempt in a dive with a Spitfire ?
Yes. There were many accidents in such testing, and several British and American pilots died. Martindale, the pilot who lost his prop in a fairly well known incident, glided his plane to a landing because if he bailed out the instruments and details of his flight would have been lost. Brave men.
How they were able to recover from it..I dunno.
That's the other part of the problem. You not only need enough thrust, you have to be able to control the plane as it reaches the sound barrier.

The 262 would have offered no control to a pilot once it exceeded it's critical mach. It would have suffered mach tuck, the dive would have steepened, and it would have done a slow outside loop, which no plane would survive at close to mach 1.
To Hop: too many words in your post pls watch carefully the pitch angle of the elevators in your Thud chart. When exceeding 500 m.p.h (or knots?) your own data sheet has well shown a banking from about 3° positive to 3° negative. THIS IS THE INVERSION OF COMMANDS!
Sorry about the length of the post. If you are using a translation tool, sorry about the poor spelling as well, which makes it more difficult.

At the start of the dive, the planes were flying quite slowly. As speed picked up in the dive, the natural tendency of the plane is to pull out, because lift increases with speed. For that reason, the elevators are puch forward to hold the plane in the dive.

At very high speeds, you get a phenomenon known as "mach tuck". The centre of pressure on the wing moves backwards, puching the nose down. At that point, the plane begins to steepen it's dive. The elevators were pulled back to stop the plane from increasing it's angle of dive.

It's not true control reversal, it's just ineffectiveness of the controls. It happens well below mach 1, the thicker the wings, the lower the speed at which it happens.

If you look at the Spitfire, it doesn't ever get as bad as the Thunderbolt, although at very high speed it no longer requires forward elevator to stop the plane pulling out.
Exactly what I said before... Cool And no WW2 fighter was equipped with any machmeter before jets.
Late war Mustangs were equipped with mach meters, which were also used in this test.
Read carefully the meaning of C.I.A.S. at the bottom of the same.
The Thunderbolt figures were not obtained by the RAE during these tests. The Spitfire and Mustang figures are EAS, which does take into account compressibility corrections.
Consequently what have you to ask more to a pilot when the wings of his plane are stripped away and the foe is gunning his own precious and unique ass? Gulf of Naples in summer '43 was not surely the comfortable US Salt Lake high speed location during '50s.
It's not a question of how brave, or frightened, the pilot is. These planes were pushed to the limits in these test. I think there were 5 pilots involved in the high speed tests for the RAE, 3 of whom died.

And these were aircraft in perfect physical condition, in some ways specially prepared for these speeds.

At these high speeds, the planes simply go out of control. The report shows that at mach 0.86, the Thunderbolt required a pull of more than 200 lbs on the elevators, and it still couldn't stop the dive from stepening of it's own accord. The Thunderbolt pilot would almost certainly have died, except his plane was fitted with dive flaps, which allowed an automatic recovery.

The "sound barrier" is something many pilots reached in WW2. Some survivied, some didn't. But the "sound barrier" begins at mach 0.8, sometimes lower, depending on the plane.


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#33

Post by Hop » 26 Jun 2004, 23:57

That's dive acceleration, though, which the Spit didn't excel in. What the Spitfire exceled in was maximum dive speed. According to the manual, the safe diving limit was limited to mach 0.85, which is higher than any other prop fighter, and higher than most of them were tested at.
Sorry, left a bit out.

There are 2 limits for a WW2 fighter. One is the mach limit, which applies at high altitude. The second is the IAS limit, which applies at low altitude.

The Spitfire had an average IAS limit, 470 mph, lower than the Tempest and Mustang (505 mph). At higher altitudes though, the Spitfire had the highest limiting mach, 0.85, 0.75 for the P-51B, 0.7 for the P-51D.

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#34

Post by Topspeed » 27 Jun 2004, 10:41

The control reversal is something different Gabriel,

It happened when jets like MIG-15 landed at low speed the ailerons somehow started to react just opposite...this was because of the foil shape kinda started to lift better on the side where the wing was supposed to lower due to control command or something ?

Hop want to shear some light on this matter here ?

Juke

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#35

Post by Topspeed » 16 Aug 2004, 18:33

So what did we conclude here. Did 262 reach the Mach 1.0 or was it just in the buffeting zone before it ?

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#36

Post by thunderw21 » 17 Aug 2004, 06:20

Being a pilot myself and having studied aircraft in general, I would have to say that no, the Me 262 did not break the sound barrier and neither did any other WW2 fighter. First of all, jet fighters did not first break the sound barrier until the 1950s, and these were still in dives. Also, the jet engines of the mid-1940s were not powerful enough to push any aircraft passed the sound barrier, even in a dive. Heck, the MIG 15 couldn't even break the sound barrier in a dive. Propellor driven aircraft of WW2 were not designed to break the barrier. I do not believe a prop aircraft can even break the sound barrier, the whirling blade just creates too much drag. I do recall a Spitfire having it's prop and engine rip off during a high speed dive test. Plus, the ME 262 nor any other WW2 airplane had a flying tail, which is required to pull out of a dive while going passed Mach 1. Again, my opinion is that it was impossible for anyone to go Mach 1 before the X-1.

MA4H Thunder :)

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#37

Post by Hop » 17 Aug 2004, 15:35

I do not believe a prop aircraft can even break the sound barrier, the whirling blade just creates too much drag. I do recall a Spitfire having it's prop and engine rip off during a high speed dive test.
The Spit in question suffered a failure of the prop pitch control, which is why it ripped off.

I know NASA spent some time designing supersonic propellers, but never reached mach 1.

With modern tech it's probably possible to get a prop plane throught the sound barrier, but no way could a WW2 fighter do it.

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Re: Did the Me 262 break the sound barrier?

#38

Post by Cantankerous » 31 Dec 2022, 06:55

Even though this thread is almost 20 years old, I found this in a 2001 Associated Press article regarding Mutke's dubious claim about breaking the sound barrier in an Me 262:
For the last several years, Otto Wagner, a professor at Munich's Technical University, has done computer simulations to try to verify Mutke's claim. He has been able to simulate the Me262 at Mach 1.02 — just above the speed of sound — but he says the basic data on the plane's aerodynamics are not reliable. He's now trying to obtain wind tunnel studies from 1944 at the Messerschmitt factory in Berlin to do a more accurate simulation.
I also should note that Messerschmitt proposed three Me 262 variants (collectively called the HG [Hochgeschwindigkeit = high-speed] series), which would have had backswept wings and horizontal stabilizers, and a top speed of about Mach 0.96 (736 mph).

Link:
https://www.secretprojects.co.uk/thread ... ants.7932/

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