Aviation myths that will not die

GregP said:

Ditching a Barracuda definitely improved the aesthetics of the rest of the sky. People would smile and women would sing. FGood would go on sale.

If ever there was an ugly aircraft, the Barracuda was one of them. Not the ONLY one, of course. One of the worst of the lot has to be the LWS-6 Zubr.



It had Jay Leno's chin, which isn't too bad on Jay, but is the pits for an airplane. Conversely, it might be Jimmy Durante's nose instead.

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Just imagine trying to ditch that bastard...

fubar57 said:

I have the Aircrew Manual for the Mk.II Steve but don't see anything about ditching. Would you like it?

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If it's anything but the 1993 version, then yes....thanks

Steve

Excellent video above, and even a mention of Major G. J. 'Lemmie' Le Mesurier, a Commonwealth ace with 5 victories (3 CR.42s and 2 Ju 87s). He shot down two of the CR.42s flying the biplane Gladiator, one of which I was watching flying in the sunshine at Duxford yesterday. It must have looked like something from WW1

The squadron was always the RAF's basic tactical unit. They did operate in pairs and sometimes even threes on occasion, on offensive operations.

Cheers

Steve

Sorry Steve, '93 version

Thanks anyway!
Cheers
Steve

How about the Myth that the P-51H was 'Fragile' compared to P-51B/D?

It is true that the XP-51F and P-51H were designed to RAF standards for high AoA lods imposed by dive pull out and high G banked turns - namely 7.3G Limit Load and 11G Ultimate Load factor.

That said, the P-51 Design loads were 8G and 12G for 8000 pounds and increasing limited as the mission loads were increased from P-51 to A-36 to P-51A to P-51B/D. At the end of the P-51D design cycle the design limit Load remained 8/12G respectively for 8000 pounds, but the design full internal combat load of 269 gallons of fuel and 1800 rounds of ammunition tipped the scales at 10,200 pounds. At that Gross Weight, the P-51D limits had reduced to 64000/10200 = 6.27G Limit Load.

The P-51H, OTOH, was designed for 7.3/11G respectively for 9500 pounds at full internal combat mission weight. If you squeezed 14 more gallons to add to the 255 gallon P-51H capacity, then the GW for EXACTLY the same internal load as the P-51D increases 84 pounds to 9584 pounds GW.

At that weight the Calcs = 7.3x 9500/9584 = 7.23G Limit load.----------> 1G greater Limit Load capability for the P-51D.

Now - had the XP-51F gone into production with a design combat load of 4x50, 1000 rounds of ammo and 180 gallons of fuel it would have done so at Design full internal combat load of 7604 with 7,3/11G Limit and Ultimate Load factors. Had the production P-51F gone into combat to meet AAF projected needs of 269 gallons, plus 55 pounds for the 85 gallon tank, plus 440 more rounds of ammo to meet the P-51B spec, then the GW increases to 8339 pounds.

At that weight the Calcs = 7.3x7604/8339 = 6.66G Limit Load ---------> still greater than the P-51D and same as P-51B. But the P-51F is 1300 pounds lighter than the P-51B with slightly greater wing area, less drag.

So why did the P-51H empty weight increase over the XP-51F by 900+ pounds you ask? The structural modifications to take the loads imposed by greater Gross weight to wing spars and longerons, and skin thickness, along with adding 25 more gallons of fuel space in the wing, a 50 Gallon fuse tank w/structure to support, a longer fuselage and a bigger empennage.

Net - drop a 1650-3 or 1650-7 into the P-51H and you have a lighter, faster, better accelerating, better tuning and climbing fighter than either the P-51B or D - and stronger besides.

Were there any important developments in materials between the b/d and the h to allow a reduction in weight without a loss of strength?

drgondog said:

How about the Myth that the P-51H was 'Fragile' compared to P-51B/D?

It is true that the XP-51F and P-51H were designed to RAF standards for high AoA lods imposed by dive pull out and high G banked turns - namely 7.3G Limit Load and 11G Ultimate Load factor.

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Bill, do you have an opinion on the myth that the Spitfire was fragile?

Teh Spitfire did grow quite a bit in weights, but it was also strengthened as it did so, in the wings and fuselage.

wuzak said:

Bill, do you have an opinion on the myth that the Spitfire was fragile?

Teh Spitfire did grow quite a bit in weights, but it was also strengthened as it did so, in the wings and fuselage.

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I reckon the Spit was as fragile as a 109s undercarriage

This old chestnut appeared on my Facebook feed. The Me262 breaking the sound barrier even though the wings would have come off long before the plane got to Mach one

Messerschmitt Me 262 Breaking the Sound Barrier, April 9th 1945

pbehn said:

Were there any important developments in materials between the b/d and the h to allow a reduction in weight without a loss of strength?

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The NAA developed their own 75ST when Alcoa could not deliver until 1945. After a dimpling process was developed to enable lighter gauge 75ST to replace thicker 24ST and still use flush rivets the skin weight was reduced.

wuzak said:

Bill, do you have an opinion on the myth that the Spitfire was fragile?

Teh Spitfire did grow quite a bit in weights, but it was also strengthened as it did so, in the wings and fuselage.

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I don't have access to necessary Spitfire docs regarding a.) original structural analysis, or b.) design changes to wings and empennage to account for increased gross weight and Q loads. Simple answer, No.

For those (or rather he) that imagine that air scoops, radiators etc would be easily stripped off an aircraft in a ditching, not 'digging in' to the water as the aircraft alighted causing serious problems I quote part of the report for the forced, wheel up, landing of the Spitfire prototype on SOLID ground.

"The intake of the radiator and oil cooler were badly torn, but the oil cooler was undamaged and the radiator appeared to be sound except for slight superficial damage to the casing...The engine bearer was badly damaged, presumably by a connecting rod coming through the crank case, but in all other respects the airframe appeared to be airworthy."

Just sayin'

Steve

Didnt the spitfire being fragile story start with wings being wrinkled when it was used as a dive bomber, personally I would take wing that bent and wrinkled thn got me home rather than simply folding up.

A few P-51s were supposed to have come back with a few more degrees of dihedral than they took of with after the pilots got "G" suits.
At least that is the story

pbehn said:

Didnt the spitfire being fragile story start with wings being wrinkled when it was used as a dive bomber, personally I would take wing that bent and wrinkled thn got me home rather than simply folding up.

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There was a 'problem' with cracks and rivet failures on the skins over the wheel wells on the Spitfire V. This typically revealed itself after approximately 100 hours flying. The Farnborough report noted that they

"..take the form of circumferential cracks between the rivets connecting the plating to the vertical wheel well. The cracks have the appearance of fatigue which suggests the presence of vibration. But the pulling out of rivets seems to confirm estimates that this panel and its attachments are highly stressed under the local pressures."

A fix was the external reinforcing strakes visible on some Mk Vs and eventually the fitting of internal reinforcement and a slightly heavier gauge skin.

There are other reports of the wrinkling of skins, but these were invariably a result of the aircraft being subjected to unusually high loading in flight. The same for the rare structural failures investigated at Farnborough.

One tailplane failed when a certain Squadron a Craxston pulled out of a dive at 465 mph. Craxston managed to land and on examination it was established that the tail plane spars were of the non-reinforced type, having been removed from X4916 and erroneously fitted to Craxston's aircraft, AA912. Incidentally, despite the accident and wild high speed oscillatons that had been violent enough for Craxston to be "thrown about the cockpit" no damage was found on the mainplane or fuselage.

Nothing in any of the reports would indicate that the Spitfire's essential design was in any way fragile. I'd definitely call that one as a myth.

Cheers

Steve

It's possible that the 'myth' of the Spitfire being fragile originated in Germany, prior to WW2, when, allegedly, Luftwaffe and RLM representatives, having seen one on a pre-war visit to England, called it 'The Toy.

stona said:

There was a 'problem' with cracks and rivet failures on the skins over the wheel wells on the Spitfire V. This typically revealed itself after approximately 100 hours flying. The Farnborough report noted that they

"..take the form of circumferential cracks between the rivets connecting the plating

stona said:

There was a 'problem' with cracks and rivet failures on the skins over the wheel wells on the Spitfire V. This typically revealed itself after approximately 100 hours flying. The Farnborough report noted that they

"..take the form of circumferential cracks between the rivets connecting the plating to the vertical wheel well. The cracks have the appearance of fatigue which suggests the presence of vibration. But the pulling out of rivets seems to confirm estimates that this panel and its attachments are highly stressed under the local pressures."8

A fix was the external reinforcing strakes visible on some Mk Vs and eventually the fitting of internal reinforcement and a slightly heavier gauge skin.

There are other reports of the wrinkling of skins, but these were invariably a result of the aircraft being subjected to unusually high loading in flight. The same for the rare structural failures investigated at Farnborough.

One tailplane failed when a certain Squadron a Craxston pulled out of a dive at 465 mph. Craxston managed to land and on examination it was established that the tail plane spars were of the non-reinforced type, having been removed from X4916 and erroneously fitted to Craxston's aircraft, AA912. Incidentally, despite the accident and wild high speed oscillatons that had been violent enough for Craxston to be "thrown about the cockpit" no damage was found on the mainplane or fuselage.

Nothing in any of the reports would indicate that the Spitfire's essential design was in any way fragile. I'd definitely call that one as a myth.

Cheers

Steve

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to the vertical wheel well. The cracks have the appearance of fatigue which suggests the presence of vibration. But the pulling out of rivets seems to confirm estimates that this panel and its attachments are highly stressed under the local pressures."

A fix was the external reinforcing strakes visible o;n some Mk Vs and eventually the fitting of internal reinforcement and a slightly heavier gauge skin.

There are other reports of the wrinkling of skins, but these were invariably a result of the aircraft being subjected to unusually high loading in flight. The same for the rare structural failures investigated at Farnborough.

One tailplane failed when a certain Squadron a Craxston pulled out of a dive at 465 mph. Craxston managed to land and on examination it was established that the tail plane spars were of the non-reinforced type, having been removed from X4916 and erroneously fitted to Craxston's aircraft, AA912. Incidentally, despite the accident and wild high speed oscillatons that had been violent enough for Craxston to be "thrown about the cockpit" no damage was found on the mainplane or fuselage.

Nothing in any of the reports would indicate that the Spitfire's essential design was in any way fragile. I'd definitely call that one as a myth.

Cheers

Steve

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Well certainly a weak hook to hang a hat on, to me just experience gained.

We had a couple of Spitfires at the Museum for many years, a Mk. IX and a Mk. XIV.

Both were WAY more fragile than a P-51.

By "fragile," I don;t mean it wasn't as strong structurally, I mean it is WAY easier to dent or rip something on a Spitfire than on a P-51. They put the strength where it was needed and didn't put much where it wasn't. Hence, the Spit was far lighter than a P-51, which translated into a lot more "hangar rash."

Personally, I love all Spitfires. Classics, to be sure, and beautiful. But saving a ton or more of empty weight comes from SOMEWHERE. In the case of the Spitfire, the fillets and other small things were a lot more fragile than on a US fighters in general. At least, that was our experience and we barred volunteers from working on them because a bit of ham-handedness could cause damage that a P-51 would shrug off.

Maintenance did not always live up to standards set by the manufacturer. The wings of AB200 were damaged after they were "inadvertently subjected to high loading in flight" by an unnamed Squadron Leader. The assessment of the damage also noted that

"Wheel well panels and stiffeners have the appearance of having been subjected to heavy upwards loading. The covering and stiffeners have further been damaged by hammering to accommodate wheel and by use of this area as a walkway."

There were also occasional issues on the production lines with wrong materials, wrong rivets or screws etc being used. In November 1942 a manufacturing errors list was prepared and it finished with these words.

"An essential part of the organisation for ensuring structural strength of aeroplanes is the arrangement whereby careful inspection is carried out at every stage from raw material right through to the finished product. As a result of non-function the structural safety of the Spitfire in certain cases is being most seriously affected."

Again, none of this implies an inherent fragility in the aircraft itself. If you don't build something correctly or fail to maintain it correctly, then you are asking for trouble.
I agree with the post above that the margins for this kind of error were smaller on the Spitfire than on some other types. There was a constant stream of instructions and advice, issued my the various technical officers, throughout the war, in an effort to ensure proper maintenance procedures for this very reason.

Cheers

Steve