Allied airframes, German parts

Lighthunmust · Jun 5, 2011

Glider said:
No problem my posting was less than clear. The German seats were far from perfect but a lot better than nothing. My understanding is that they were used about 70 times during the war, and I am very confident that those who used them, loved them.

Initially the seats were powered by compressed air but were soon changed to cartridge powered. At least one fighter a He219, was hit in the compressed air tank and the resultant rupture of the tank forced a crashed landing.

Now that you mention them, anybody ever heard the story that the Germans ran low of explosives and resorted to dropping cylinders of compressed air? My Scuba instructor in my freshman year of high school tried to use that nonsense to impress us with the danger of dropping our tanks!

Do you have any information on fatalities due to malfunction of the German ejectors seats? I have heard of at least one example.

P.S. Its a riddle not a quiz. Nobody has to pass, it just for amusement and to stimulate discussion. The riddle has succeeded in stimulating posts with good information. I wish someone would give more details of using zinc chromate for smoothing surfaces. I had only heard of its use for corrosion resistance.

razor1uk · Jun 5, 2011

Would that zinc chromate be used in a hot, swirly whirly whooshing kind of working environment?

tomo pauk · Jun 5, 2011

Lighthunmust said:
Reliable as defined by what standard?

By standards of non-mentioning the issue from late 1942 on?

Ammunition supply was still to low for the hit probabilities of air to air, and power was to low for anti-tank.

Agreed on anti-tank capability, but that was not the purpose of the plane anyway.
While I agree that ammo capacity was low, firing time was 20 sec with that gun. So the ammo capacity did not hamper hit probability in any way.

The one thing the P-39 didn't need from the Axis or Allies was improvements to beauty, it was gorgeous.

Very streamlined plane, at least to say.

Lighthunmust · Jun 5, 2011

tomo pauk said:
By standards of non-mentioning the issue from late 1942 on?

Agreed on anti-tank capability, but that was not the purpose of the plane anyway.
While I agree that ammo capacity was low, firing time was 20 sec with that gun. So the ammo capacity did not hamper hit probability in any way.

Very streamlined plane, at least to say.

Twenty seconds of firing with enormous amounts of time (for evasive targets) between shots. Sure one hit and its probably all over for most opponents, but accuracy requirements are very difficult. I seem to recall there were many 37mm misses for every F-86 shot down by 23mms from Mig-15s. That of course is another story. Not many fighters today using fast firing, low ammunition capacity, 37mm rotary cannons. That too is another story.

tomo pauk · Jun 5, 2011

(boy, do I like to beat stuff to death sometimes )

Twenty seconds of firing with enormous amounts of time (for evasive targets) between shots.

Considering that 70-80% (would like that somebody correct/approve the numbers) of all planes shot down were not aware of imminent danger, rate of fire was rather sufficient.

Sure one hit and its probably all over for most opponents, but accuracy requirements are very difficult.

IIRC Thatch said that a pilot unable to hit anything with 4 MGs will miss with 8 MGs on-board.

I seem to recall there were many 37mm misses for every F-86 shot down by 23mms from Mig-15s. That of course is another story.

Perhaps JoeB can enlighten us in this issue? How easy was to tell what cannon claimed a Sabre anyway?

Not many fighters today using fast firing, low ammunition capacity, 37mm rotary cannons. That too is another story.

They use mostly missiles to kill other planes, managing some 1 (or less?) kill per 10 missiles expanded.

Lighthunmust · Jun 5, 2011

tomo pauk said:
(boy, do I like to beat stuff to death sometimes )

Considering that 70-80% (would like that somebody correct/approve the numbers) of all planes shot down were not aware of imminent danger, rate of fire was rather sufficient.

IIRC Thatch said that a pilot unable to hit anything with 4 MGs will miss with 8 MGs on-board.

Perhaps JoeB can enlighten us in this issue? How easy was to tell what cannon claimed a Sabre anyway?

They use mostly missiles to kill other planes, managing some 1 (or less?) kill per 10 missiles expanded.

After reading many old threads about cannon versus machineguns, and a few new posts since I became a forum member; I am proud to be in the good company of murderous stuff beaters who think the issue unsettled.

Maybe sufficient at very, very close range or with an excellent marksman. Also consider that unaware target and the attacker are moving in multiple directions simultaneously every second. Aircraft don't fly smoothly in one direction as if on rails.

Four, count 'em, 4, much faster firing weapons with many more projectiles per burst, at targets only needing a few hits per many misses to be effective. I don't think your Thatch reference works. Anyone want to speculate that Thatch would have preferred one 37mm and a couple of .50s? He was an experience gunnery instructor before the war so maybe it would work out for him, but I doubt he would believe it was the best option for average pilots.

I hope JoeB can provide information. It is my understanding that the only reason the MiG had a 37mm was that the Soviets specified it for destroying B-29s. The caliber 37mm does not last long as a MiG armament, it was not used in the MiG-19 or later MiGs. Nobody today specifies 37mm caliber even for ultra-fast rotary cannons. Gotta be a reason.

I always hope to be educated more than educating when participating in these discussions. Thank you to all forum members for the education.

tyrodtom · Jun 5, 2011

The Mig-15 was origionally designed to counter the B-29, B-50, and B-36 bombers that the Soviets though they would be facing in the next war.
And they were very effective against the B-29's over Korea. But i'll leave the determination about how much of that was due to the 37 mm, or the two 23mm's they carried, to someone else, because I could only guess.

Shortround6 · Jun 5, 2011

tomo pauk said:
Considering that 70-80% (would like that somebody correct/approve the numbers) of all planes shot down were not aware of imminent danger, rate of fire was rather sufficient.

Rate of fire for the US 37mm M4 cannon may be in dispute. Dean says 90 rpm and the firing time of 20 seconds for 30 rounds of ammo.
Tony Williams says 140-150 rpm for a firing time of 12-13 seconds.
Melvin Johnson says 125 rpm or a firing time of 14.4 seconds.

For those who bring in the Korea and the Mig 15 it used a different cannon the the WW II Soviet 37mm. It fired at 400rpm and ran out of shells in about 6 seconds.

tomo pauk said:
IIRC Thatch said that a pilot unable to hit anything with 4 MGs will miss with 8 MGs on-board.

Thach began training as a Naval Aviator in 1929 and spent time as an aerial gunner instructor before making squadron commander. His experience and expectations may have been a bit different than an "average pilot" who started training in 1942.

tomo pauk said:
Perhaps JoeB can enlighten us in this issue? How easy was to tell what cannon claimed a Sabre anyway?

I don't know if it is true but they say that no Sabre survived a 37mm hit although a number came back with 23mm hits. Not much to go except a negative there.

Lighthunmust · Jun 5, 2011

Shortround6 said:
Rate of fire for the US 37mm M4 cannon may be in dispute. Dean says 90 rpm and the firing time of 20 seconds for 30 rounds of ammo.
Tony Williams says 140-150 rpm for a firing time of 12-13 seconds.
Melvin Johnson says 125 rpm or a firing time of 14.4 seconds.

For those who bring in the Korea and the Mig 15 it used a different cannon the the WW II Soviet 37mm. It fired at 400rpm and ran out of shells in about 6 seconds.

Thach began training as a Naval Aviator in 1929 and spent time as an aerial gunner instructor before making squadron commander. His experience and expectations may have been a bit different than an "average pilot" who started training in 1942.

I don't know if it is true but they say that no Sabre survived a 37mm hit although a number came back with 23mm hits. Not much to go except a negative there.

Even with a 400 rpm it was still slow, the pilot was using an inferior gunsight, and better get it right in 2 or 3 bursts or no more ammo. I too have always heard no fighter survived a 37mm hit. I guess I'm back to the sufficient power argument. One or two more 23mm cannon firing more shells may have caused enough hits to break more Sabres. The Soviets specified three 30mm for the MiG-19.

Glider · Jun 6, 2011

Lighthunmust said:
Four, count 'em, 4, much faster firing weapons with many more projectiles per burst, at targets only needing a few hits per many misses to be effective.

You hav mentioned the much faster firing weapons can I aask what you are comparing against what?

drgondog · Jun 6, 2011

Lighthunmust said:
I wish someone would give more details of using zinc chromate for smoothing surfaces. I had only heard of its use for corrosion resistance.

I wish I had more specifics for you. I have the drawings/BOM. I don't have the time to research them at the moment.

The assembly line pics I have seen that are in color 'suggest' Zinc Chromate but do not so state!

Lighthunmust · Jun 6, 2011

Glider said:
You hav mentioned the much faster firing weapons can I aask what you are comparing against what?

M4 and M10 versus M2

Number of projectiles per burst of one 37mm versus number of projectiles per burst of four .50s

The larger gaps in the 37mm projectile stream than the .50cal projectile stream

Higher probability of average pilots missing more frequently with a 37mm than four .50s

Sufficiency of power from multiple .50cal hits being a better option than the devastating power of one 37mm hit for multiple firing passes at multiple targets making rapid transitions in multiple directions.

Sufficient ammunition capacity to compensate for inherent mechanical accuracy of the weapons, gunsight technology, type and amount of gunnery training pilots received, and average ability of pilots under the stress of combat.

Lighthunmust · Jun 6, 2011

drgondog said:
I wish I had more specifics for you. I have the drawings/BOM. I don't have the time to research them at the moment.

The assembly line pics I have seen that are in color 'suggest' Zinc Chromate but do not so state!

I understand the time constraints and only asked on the hope you had information readily at hand. I'm really glad you brought this up. I'll try to find more myself.

Lighthunmust · Jun 6, 2011

There actually was something extremely valuable the Germans "had" that made the airframe of the P-51 better than anything the genius of Willie Messerschmitt put into any version of the Bf109. Does anyone on this forum know what it was?

Clues:

1. Use non-linear thinking.

An aircraft is more than the sum of the hardware parts it contains.

2. It was something the genius of Willie Messerschmitt could not contribute.

Messerschmitt was in Germany, so physically unavailable.

3. Germany "had" it prior to WW2.

Germany had the citizenship of Edgar Schmued until he became an American in the 1930s.

4. Fokker contributed to making it available.

Schmued held a job with GM in Brazil, and latter a job with GM in the U.S. when GM represented Fokker. Multi-year employment during the Depression with an American company and turmoil in Germany certainly influence Schmued to become an American citizen.

5. It required over 30 years of development before it would be available for NAA.

By the time Schmued was available to design for NAA his aviation ingenuity had been developing for over 30 years.

6. The answer can be given with one sentence if necessary.

The genius/ingenuity Edgar Schmued instilled into the assemblage of hardware parts that a Mustang contains.

Can you imagine how bad things would have been for the Allies if those P-51s with German insignia you see in the movie "Fighter Command" were a reality in 1942?

drgondog · Jun 6, 2011

You will find few people that admire Schmeud or Kelly Johnson more than me. Having said that there were a lot of basic science/math/airframe guys that are imbedded in the Mustang (and F-86) than one great Design engineer, ditto the team on the F-12/SR-71. Schmeud's genius, like Johnson's was an incredible multi discipline engineering background to field and parse all ideas from BS to pure art and sunshine of intellect.

This is from the Osprey "Production Line to Frontline" book, page 16 and other pages:

"At the factory, the wings were primered and finished with airfoil smoother. The first 40 per cent of the wing chord was shot with one coat of zinc chromate primer. This was then followed by enough coats of Acme Gray Surfacer No 53N5 to cover all irregularities. Skin butt joints were then filled with Acme Red Vellunite glazing putty no 58485. The entire area was then sanded down and sprayed with one coat of camouflage enamel (when camouflage was deleted, the forward portion of the wing was sprayed silver). This was a simple and quick way to create a nearly perfect laminar flow surface, but one has to wonder just what effect all those size 12 GI boots (warn by both air- and groundcrew) in the field had on the carefully-applied laminar flow finish!."

bobbysocks · Jun 6, 2011

zinc chromate primer's main role was to bond paint to the difficult aluminum surface. if you ever painted aluminum its a B!T<# !!! regular ( acrylic and enamel ) paints and primers dont want to stick. there are several ways to accomplish surface prep. in addition to roughing the surface up by sanding the prefered method is to acid etch the surface which will create millions of microscopic craters and crevasses for the paint to flow into and adheare. but when you had panels rivited together that acid would seep between the plates and to areas not covered and protected by the primer. this etching "lays the metal open" and could accelerate corrosion in those areas and is less that desireable. the other method is to use a chemical bonding agent. zinc chromate filled that role for non ferris metals. i am not a chemist so i can not explain why. zinc is also used in galvanization to provide resistance to corrosion. how much of that comes into play...?? i am not a chemist. all i know in my years of selling paint and being around aircraft ZC was the only way to keep paint on a plane but was not used in other applications such as automotive. if it had superior corrosion resistance for ferris metals it would have been the base coat on all autos, tractors, etc. and up until the late 90s i can guarentee you it wasnt.

Lighthunmust · Jun 6, 2011

drgondog said:
You will find few people that admire Schmeud or Kelly Johnson more than me. Having said that there were a lot of basic science/math/airframe guys that are imbedded in the Mustang (and F-86) than one great Design engineer, ditto the team on the F-12/SR-71. Schmeud's genius, like Johnson's was an incredible multi discipline engineering background to field and parse all ideas from BS to pure art and sunshine of intellect.

This is from the Osprey "Production Line to Frontline" book, page 16 and other pages:

"At the factory, the wings were primered and finished with airfoil smoother. The first 40 per cent of the wing chord was shot with one coat of zinc chromate primer. This was then followed by enough coats of Acme Gray Surfacer No 53N5 to cover all irregularities. Skin butt joints were then filled with Acme Red Vellunite glazing putty no 58485. The entire area was then sanded down and sprayed with one coat of camouflage enamel (when camouflage was deleted, the forward portion of the wing was sprayed silver). This was a simple and quick way to create a nearly perfect laminar flow surface, but one has to wonder just what effect all those size 12 GI boots (warn by both air- and groundcrew) in the field had on the carefully-applied laminar flow finish!."

I agree completely about it being a team effort. Most complex engineering tasks are a team effort. When I was younger (1960s) one book said James "Dutch" Kindelberger deserved the credit for the Mustang's design. In the 1980s I remember reading about the claims of Lee Atwood that he was responsible for the design. Edgar Schmued deserves the lions share of credit for the success of the design, something not well publicized until after his death.

Thanks for the information on the finishing and the source. Considering all the unpainted P-51s at the end of the war, was this not just a colossal use of time for little benefit?

After reading Bobbysocks post, I can understand the need to prime for camouflage paint. I'm slapping my forehead for not thinking of that.

bobbysocks · Jun 6, 2011

Lighthunmust said:
Thanks for the information on the finishing and the source. Considering all the unpainted P-51s at the end of the war, was this not just a colossal use of time for little benefit?

i would be interested in knowing the difference in weight of the ac between painted and unpainted. I know when USAirways went to the blue/gray color scheme back in the 90s. the difference did effect the load capacity of the ac. between the external primers (you would have to protect the interior parts regardless with ZC ), sealers, finishing putty, and final top coats it could be in excess of a couple hundred pounds.

Jabberwocky · Jun 7, 2011

Mike Williams said:
Hi Jabberwocky: I've read (and seen first hand in restored jobs) that the leading edge of the Mustang's wing was filled and sanded smooth, even in otherwise bare metal models. It's mentioned in various flight tests such as these:

P-51B-1-NA, AAF No. 43-12093, Preliminary high speed and climb performance tests
"Finish was filled and sanded and was supposed to be the standard production finish."

Mustang IV T.K.589 Position error of static vent and brief level speed trials
"The aircraft was not painted. The under surface of the wings back to the main spar and the whole of the top surface had been coated with a smooth composition, the joints being filled and the remainder being bare metal. The fuselage was left with the bare metal except for a matt anti-glare finish on the top engine cowling."

Did you ever see the Smithsonian's Spitfire VII? That thing is clean! The finish is filled and sanded and there is hardly a rivet to be seen.

I haven't seen the Smithsonian's Mk VII, but I've been up close with a Mk VIII in Australia and a couple of Mk Is, a Mk II and a Mk Vc in the UK.

The difference that was most noticeable was the fit of the panels.

The Mk I was quite fiddly, with more small panels on the nose, lots of domed rivet heads and inconsistent panel gaps. There was notable warping of the fuselage skin aft of the Merlin firewall on one example.

The Mk II was quite a bit neater, with less overhangs on panel edges and smoother skinning on the fuselage.

The Mk V was perhaps the poorest of the lot: some big panel gaps, panel warping on the lower nose and an overall lack of fit and finish. I was really surprised at how it looked like it had been banged together with a couple of hammers by hand, rather than created as part of an assembly line process that made more than 20,000 Spitfires.

The Mk VIII was much smoother. More 'industrial' looking. Panel gaps were both smaller and more consistent. Flush riveting used throughout and there was less warping on the wing surface and fuselage. Also the use of fewer and larger panels, like under then nose and immediately in front of the cockpit, adds to the overall impression of better streamlining.

Of course, these aircraft are 70-75 years old now and the restorations have been of varying quality and are a bit of a hodge podge so the criticisms may be a little unwarrented.

The Mk V I saw had a 4 blade prop and six stack multi-ejectors but the cannon were gone, although the associated bulge on the wing remained: a legacy of the 'Battle of Britain' movie would be my guess. There is no telling how much rough treatment it suffered since WW2.

tomo pauk · Jun 7, 2011

Lighthunmust, thank for educating me about Edgar Schmued

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