The sound barrier

Interesting discussion so far.

But I have to agree with Bill here and say:

Soren if you are going to claim something and site "professional sources" then you need to provide the sources.

Now having said that:

What me and the other moderators said in the Panzer thread, applies to this thread as well. As soon as this thread gets out of hand, the thread will be closed and the effected parties will take an extended vacation.

We do not need any childish bullshit here.

Soren said:

A normal Me-262 in 1945 wasn't of very good quality Juha, so obviously there would be structural issues.

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Mirrioring what already been said.

For a statement like you you're going to have to show where the quality of latter model 262s were deficient enough to cause structural issues. I would agree that there was degradation across the board on all aircraft being built by Germany towards the end of the war, but having built several hundred aircraft and drones myself, its actually pretty hard to screw up the assembly of a structure when it is built in a jig, and I do now that all 262s were jig built. Unless there were deficiencies in sub assemblies, heat treating and processing of structural parts or some other core systemic deficiency, a few poorly driven rivets aren't going to make a difference in the long run unless they happen to be holding major components together, and again it would be highly suspect to try to attempt to put a finger on where and when something like that was to happen in the aircraft's production.

Ok for the sake of preserving the interesting nature of this discussion I'm gonna ignore Bill's insults and attempt at starting a mud throwing contest.

The sources for my claims are Mutke's own description of what happened coupled with the findings of the study done in Germany in 1999.

Ok you want me to provide the 1999 Study, well atm. I can't because I don't have it, I've made that clear multiple times by now. I first read it a couple of years back and saved it somewhere.

But I am not the only one to draw attention to that study, Delcyros was the first IIRC and he also didn't provide it for anyone to see, yet no one complained. However Bill insists I provide it for some reason, but only because he has run dry of arguments himself IMO. (Which is also the reason he finds it necessary to throw insults at me, which I am not going to pursue)

Moving on…

For the sake of simplicity let me summarize the arguments brought forth:

I say the Me-262 quite clearly broke the sound barrier because as Mutke explains the heavy vibrations and uncontrollable pitch down his a/c exhibited while in the transonic region suddenly seized and a smooth ride followed while still in the dive, after which he shut his engines and started to trim the tail plane to recover from the dive (The all moving tailplane is what allowed him to recover from the dive as shockwaves rendered the elevators ineffective), shortly after the vibrations started again. This to me is a clear sign that he went supersonic. And studies done in Germany in 1999 prove that it was possible for the Me-262 to go supersonic, but it was risky and damage to the a/c was almost assured, and depending on the quality of the workmanship of the airframe it could come apart in the attempt as-well.

Further proof that the Me-262 either went supersonic or came extremely close to it is the British claims that the Spitfire, a propeller driven a/c, reached Mach 0.9 in dives. The claim is substantiated by the fact that the speeds were recorded to be viewed afterwards. The Spitfire featured no wing sweep and being a propeller driven a/c it had absolutely no thrust at such high speeds, so to explain why the a/c was capable of such a speed it is claimed that it is the unusually thin airfoil which gave the a/c its high Mach number.

Keeping the above in mind it should be mentioned that the Me-262 not only featured a thinner wing than the Spitfire but also wing sweep, and even more crucial is the fact that the Me-262 is a Jet and thus has available a lot of thrust at high speeds. Furthermore the Me-262 is a much cleaner a/c than the Spitfire.

In level flight the average Me-262 achieved a top speed of Mach 0.77 to 0.79 at a height of 6km (The British established the top level speed to be 900 km/h in several recorded flights).

So there is absolutely no doubt in my mind that the Me-262, along with the Me-163 F-86 Sabre, broke the sound barrier before Chuck Yeager in his X-1 craft.

but you reject other claims by Brit tests regarding a Spit diving speed held under test conditions, or Encounter reports claiming '660 mph' dive in a Mustang.

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Bill that is a lie, I never mentioned the Mustang, all I said was I doubt that the Spitfire ever reached Mach .9 in a dive, I think Mach .82 seems a lot more reasonable.

Fabricating stuff definitely doesn't bolster your own credentials Bill.

FLYBOYJ said:

Mirrioring what already been said.

For a statement like you you're going to have to show where the quality of latter model 262s were deficient enough to cause structural issues. I would agree that there was degradation across the board on all aircraft being built by Germany towards the end of the war, but having built several hundred aircraft and drones myself, its actually pretty hard to screw up the assembly of a structure when it is built in a jig, and I do now that all 262s were jig built. Unless there were deficiencies in sub assemblies, heat treating and processing of structural parts or some other core systemic deficiency, a few poorly driven rivets aren't going to make a difference in the long run unless they happen to be holding major components together, and again it would be highly suspect to try to attempt to put a finger on where and when something like that was to happen in the aircraft's production.

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FLYBOYJ,

The German industry was under a lot of stress as the war went on, having to finish a/c at increasing paste while proper materials and resources were in short supply and the factories were being bombed. All this resulted in that the Me-262's contructed in 1945 were subject to shabby workmanshipby comparison to those built in mid to late 1944. By 1945 all German a/c were being hurridly put together in order just to get 'something' in the air to counter the Allies, the Germans were desperate. The quality of the workmanship of the 109's built in 1945 was but a shadow of what it was a mere half a year earlier.

Soren said:

FLYBOYJ,

The German industry was under a lot stress as the war went on, having to finish a/c at increasing paste while proper materials and resources were in short supply and the factories were being bombed. All this resulted in that the Me-262's contructed in 1945 were subject to shabby workmanshipby comparison to those built in mid to late 1944. By 1945 all German a/c were being hurridly put together in order just to get 'something' in the air to counter the Allies, the Germans were desperate.

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Show me specifically where and how these aircraft were deficient or suspect to have structural integrity problems? What you said could be applied to just about any German aircraft of the period but to say their structural in integrity was suspect is far reaching unless you have facts. Poor workmanship in assembly would be noted (rivet flushness, gap and mismatch, rework of discrepancies, etc.) but that doesn't necessarily mean the aircraft will have structural problems.

Personally I believe the Me 262 "could have" gone super sonic IF the engines didn't flame out in the trans sonic range, IF the aircraft did hold together and IF the pilot did the right thing to recover so he didn't wind up as a statistic. There's a lot more ifs tied to this so to me it's possible but not probable and in the end I really doubt it happened and even if it did I also doubt the guy flying it would live through it. (And I don't believe Mutke actually went supersonic, close but not truly mach 1)

Bottom line, you could make a brick go supersonic if you put enough thrust behind it.

no further comment

Moving on to a slightly different topic: Does anyone have info on the Me 262 HG-I's (the one actually flight tested) critical Mach number and control characteristics when this speed was reached?

The 004 has neither a convergent-divergent nozzle nor reheat and so the thrust massively drops off by Mach 1. Far more important is the fact that you're in a dive and gravity is pulling you earthwards - which is why a Spitfire can accelerate up to M0.94.

The Me 262 had negligible wing sweep. The effect can be calculated by taking the Cosine of the sweep angle. This reduces the effective thickness by an entire 5% to give an effective thickness of 10.5%. This is a far cry from the 5% and 6% t/c for other high transonic aircraft (and most are much cleaner designs)

Bottom line, you could make a brick go supersonic if you put enough thrust behind it.

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Its called the Space Shuttle.

Soren
I wonder how you can first try to proof a claim with a fact

Quote: "Further proof that the Me-262 either went supersonic or came extremely close to it is the British claims that the Spitfire, a propeller driven a/c, reached Mach 0.9 in dives. The claim is substantiated by the fact that the speeds were recorded to be viewed afterwards. The Spitfire featured no wing sweep and being a propeller driven a/c it had absolutely no thrust at such high speeds, so to explain why the a/c was capable of such a speed it is claimed that it is the unusually thin airfoil which gave the a/c its high Mach number."

And then in the next message dispute the very same fact

Quote: "all I said was I doubt that the Spitfire ever reached Mach .9 in a dive, I think Mach .82 seems a lot more reasonable."

After all drag raise is very steep after say Mach 0.75 (depending on a/c). So if Spitfire's max was Mach 0.82 how that support Mutke's claim? The question is only rhetorical one.

And as Bell X-1 showed, wing sweep wasn't mandatory to high transonic/supersonic speeds.

Juha

Juha said:

Soren
I wonder how you can first try to proof a claim with a fact

Quote: "Further proof that the Me-262 either went supersonic or came extremely close to it is the British claims that the Spitfire, a propeller driven a/c, reached Mach 0.9 in dives. The claim is substantiated by the fact that the speeds were recorded to be viewed afterwards. The Spitfire featured no wing sweep and being a propeller driven a/c it had absolutely no thrust at such high speeds, so to explain why the a/c was capable of such a speed it is claimed that it is the unusually thin airfoil which gave the a/c its high Mach number."

And then in the next message dispute the very same fact

Quote: "all I said was I doubt that the Spitfire ever reached Mach .9 in a dive, I think Mach .82 seems a lot more reasonable."

After all drag raise is very steep after say Mach 0.75 (depending on a/c). So if Spitfire's max was Mach 0.82 how that support Mutke's claim? The question is only rhetorical one.

And as Bell X-1 showed, wing sweep wasn't mandatory to high transonic/supersonic speeds.

Juha

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Pretty good summary Juha. The other wildcard is that apparently the Spit did not suffer a 'pitch down' moment coefficient as it went transonic over the wing - unlike the 262.

Nothing like becoming a cloud of aluminum fragments to slow one's progress toward Mach 1.

FLYBOYJ said:

Show me specifically where and how these aircraft were deficient or suspect to have structural integrity problems? What you said could be applied to just about any German aircraft of the period but to say their structural in integrity was suspect is far reaching unless you have facts. Poor workmanship in assembly would be noted (rivet flushness, gap and mismatch, rework of discrepancies, etc.) but that doesn't necessarily mean the aircraft will have structural problems.

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Well as you know at close to Mach 1 even small defeciencies can be fatal. Lets say a panel comes off at Mach 0.85 because of a small gap made in assembly, well that could cause the whole a/c to come apart.

The pace at which a/c were being contructed in 1945 as well as, and no less, the circumstances under which they were made, enevitably caused a lot of quality issues. But to make matters even worse the LW, in order to get enough a/c in the air, had to significantly lower their quality acceptance demands. Hans Fey also notes the lower quality acceptance demands and differing workmanship between a/c in the report on the site I referenced earlier.

Infact by 1945 Hungarian built 109's were considered to be of much better quality than German built ones.

Bottom line, you could make a brick go supersonic if you put enough thrust behind it.

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Yes, but will it stay together ?

Juha said:

Soren
I wonder how you can first try to proof a claim with a fact

Quote: "Further proof that the Me-262 either went supersonic or came extremely close to it is the British claims that the Spitfire, a propeller driven a/c, reached Mach 0.9 in dives. The claim is substantiated by the fact that the speeds were recorded to be viewed afterwards. The Spitfire featured no wing sweep and being a propeller driven a/c it had absolutely no thrust at such high speeds, so to explain why the a/c was capable of such a speed it is claimed that it is the unusually thin airfoil which gave the a/c its high Mach number."

And then in the next message dispute the very same fact

Quote: "all I said was I doubt that the Spitfire ever reached Mach .9 in a dive, I think Mach .82 seems a lot more reasonable."

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I was presenting arguments from all parties Juha.

I was making the point that how can people who support that the Spitfire reached Mach 0.9 in a dive not support that a much cleaner a/c, with a thinner wing, with sweep (Every little helps), a Jet infact, reached Mach 1 in a dive?

After all drag raise is very steep after say Mach 0.75 (depending on a/c). So if Spitfire's max was Mach 0.82 how that support Mutke's claim? The question is only rhetorical one.

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Well it supports it a lot in my mind as the Me-262 was over 200 km/h faster in level flight.

And as Bell X-1 showed, wing sweep wasn't mandatory to high transonic/supersonic speeds.
Juha

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True, but every bit helps Juha.

PS: The X-1 barely had any wings, more like fins

Soren said:

Well as you know at close to Mach 1 even small defeciencies can be fatal. Lets say a panel comes off at Mach 0.85 because of a small gap made in assembly, well that could cause the whole a/c to come apart.

The pace at which a/c were being contructed in 1945 as well as, and no less, the circumstances under which they were made, caused some a lot of quality issues. But to make matters even worse the LW, in order to get enough a/c in the air, had to significantly lower their quality acceptance demands. Hans Fey also notes the lower quality acceptance demands and differing workmanship between a/c in the report on the site I referenced earlier.

Infact by 1945 Hungarian built 109's were considered to be of much better quality than German built ones.

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Do you have any evidence of any 262s coming apart during normal combat, affected by the lower quality standards? The bottom line is you're only speculating on something that may or may not existed. I've assembled and worked on MiG-15s from USSR, Poland and China and I could see the difference in the quality of the aircraft, but I could also say despite the lower quality of one to another there's going to be little or no difference the way each one will fly.

Soren said:

Yes, but will it stay together ?

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I'd give it about the same odds as a 262 or any other aircraft where the designer says not to exceed critical mach number - BTW, the MiG-15 was in the same boat - Could it exceed mach 1? Possibly, but the odds are the pilot won't live to tell about it

FLYBOYJ said:

Do you have any evidence of any 262s coming apart during normal combat, affected by the lower quality standards?

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Infact yes I have, Prof. Doetch's envestigations done in 1944 which concluded that many of the Me-262's lost in combat due to unexpectingly falling apart in dives were because of poor quality workmanship on some ships.

The bottom line is you're only speculating on something that may or may not existed.

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No as envestigations done in 1944 prove that there were infact quality issues which caused fatal crashes than I aint really speculating just citing.

I've assembled and worked on MiG-15s from USSR, Poland and China and I could see the difference in the quality of the aircraft, but I could also say despite the lower quality of one to another there's going to be little or no difference the way each one will fly.

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MIG production facilities weren't being bombed, manned by slave labor or lacked any resources or materials.

I'd give it about the same odds as a 262 or any other aircraft where the designer says not to exceed critical mach number

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First of all Willy wasn't the designer, and secondly all that was concluded was that at Mach .86 the Me-262 would enter an untrollable pitch down dive, the increasing negative G-forces eventually breaking the a/c apart.

- BTW, the MiG-15 was in the same boat - Could it exceed mach 1? Possibly, but the odds are the pilot won't live to tell about it

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Yet the F-86 Sabre did it, regularly..

drgondog said:

Pretty good summary Juha. The other wildcard is that apparently the Spit did not suffer a 'pitch down' moment coefficient as it went transonic over the wing - unlike the 262.

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That is probably because the Spitfire never went fast enough for it to happen. There's a reason the all moving tail-plane was such an important feature.

"The aircraft's design introduced many innovations which are still used on today's supersonic aircraft. The single most important development was the all-moving tailplane, giving extra control to counteract the Mach tuck which allowed control to be maintained to and beyond supersonic speeds. This was wind-tunnel tested at Mach 0.86 in 1944 in the UK.[6] In the immediate postwar era new data from captured German records suggested that major savings in drag could be had through a variety of means such as swept wings, and Director of Scientific Research, Sir Ben Lockspeiser, decided to cancel the project in light of this new information. Later experimentation with the Miles M.52 design proved that the aircraft would indeed have broken the sound barrier, with an unpiloted 3/10 scale replica of the M.52 achieving Mach 1.5 in October 1948."

The fact that the Spitfire was not a jet doesn't really prove anything wrt the 262. It is after all a matter of record that the Spitfire dived faster than the Meteor, Vampire and P-80, all jets. It only proves that the Spitfire could dive at an exceptional speed for its class of aircraft.

secondly all that was concluded was that at Mach .86 the Me-262 would enter an untrollable pitch down dive, the increasing negative G-forces eventually breaking the a/c apart.



isn't that the point?

Soren said:

Infact yes I have, Prof. Doetch's envestigations done in 1944 which concluded that many of the Me-262's lost in combat due to unexpectingly falling apart in dives were because of poor quality workmanship on some ships.

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So what makes you believe that those built in 1944 with "some" flaws had the same chances of coming apart as those built later? Do have serial numbers and dates they were produced? Lot numbers, etc?

Soren said:

No as envestigations done in 1944 prove that there were infact quality issues which caused fatal crashes than I aint really speculating just citing.

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Oh so if it happened in 44' then some of those incidents "could of" been at the front of the production run, when the quality was higher?

Soren said:

MIG production facilities weren't being bombed, manned by slave labor or lacked any resources or materials.

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Slave labor yes as well as unqualified labor as well.

Soren said:

Do I have to repeat that Willy wasn't the designer ?

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No he wasn't but he was the head of the design team and the buck stopped with him. In the book "Arrow to the future" by Walter Boyne there is a very detailed organization chart of how he and his design team interacted and the bottom line here is a limitation was placed on the airframe - Willy would of had the final say taking into consideration input from his aerodynamicists as well as design and stress engineers. On page 108 of the book it list "Prof. Messerschmitt as chief engineer with Fronklich, Rethel, reporting directly to him and Voigt underneath Williy

Soren said:

Yet the F-86 Sabre did it, regularly..

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And it did - and those who designed it knew it could do so with ease including the chief test pilot who proceeded to do so days before Yeager did, but the only proof of that is the dozens of people who heard the "boom." Without witnesses and telemetry equipment it is speculation, just like Mutke's flight.

Slight digression here but wasn't the first British pilot to exceed Mach 1 Roland Beaumont in a USAF F-86? Albeit unofficially. I'm sure I read that somewhere.

The MiG 15 had its tail mounted near the top of a very large fin, surely a major flutter problem when nearing mach unity? When they built a supersonic fighter MiG moved the tail to ther rear fuselage, like it was on the F-86