What if America built De Havilland Mosquitoes instead of the B-17 Flying Fortress?

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No it was not at all a problem of UK vs US inches - it was that Lee Enfield had their own inch that nobody else used.
For those not familiar with the story, Enfield used standards based on the Imperial standard yard that was destroyed when Parliament burned. The new standards distributed in 1855 were supposed to be as close as possible to the old standard based on existing copies but it didn't quite match Enfield.
 
Oh dear, a basic mistake in QA/QC the first topic of every discussion, is everybody using the latest revision of specifications and documents.

When I worked to API X65 5 years ago the min yield strength of X65 (65,000 PSI) was 448 MPa and that is the official conversion, I looked it up yesterday on the net and the value has been rounded up to 450 Mpa.
 
It all reminds me of the state legislature that several years ago voted to standardize pi as "3." At least we don't redefine a foot on the size of a king's foot every time a new monarch takes the throne...

Cheers,



Dana
Pi is the ratio of circle circumference to diameter. There is a passage in the Old Testament about a giant bowl built for King Solomon and the circumference and diameter quoted for it have a ratio of three so that is the correct value for pi. Of course, if you have a six inch slide rule and aging eyes, there isn't much difference between 3 and 3.14.
 
Point of order, the Romans didnt have a decimal point, Pi is 3 to no decimal places, 3.14 is also 3 when rounded to an integer.
 
The problem with the A-36 was for every A-36 you built you didn't have a P-51. (But really, the A-36 was only meant to be a placeholder to keep the assembly lines running during a short funding gap. Later the USAAF found out the A-36 exceeded expectations. Then again, the Allison-engined P-51 and P-51A did too. By the time The P-51A was showing itself in service, plans were already in place for the Merlin-engined P-51B.
 
If the Army had swallowed it's pride and had their A-24 pilots go through the Navy's SBD training, it would have been far more potent in the PTO and thus, a potential Ground attack platform in the MTO/ETO. As it was, A-24 pilots were trained to attack at a 30° to 45° angle, more of a "glide-bomb" profile, than using the A-24 as designed.
In all, the Army received 168 A-24 (SBD-3), 170 A-24A (SBD-4) and 618 A-24B (SBD-5) types. That was nearly 1,000 potentially lethal dive-bombers that could have yeilded results at time when it was much needed.
 
The A-36 Mustang served two puposes and you clearly identified one - namely interim funding to bridge NA-91 Mustang IA. The second was combined 'political' and best for a job urged by Asst SoW Bob Lovett on Hap Arnold beginning in 1940 when reports of Stuka CAS were filtering in to AAF HQ. When the A-36 actually began combat ops, the AAF doctrine for CAS had moved from a posture of dive bombing capability 'useful' to the notion that a fast attack fighter (P-51A/P-51B, P-47) 'better'.

On the latter point. The production of A-36/P-51A and P-51B co-existed at Inglewood. By the time P-51A emerged for first flight in first week of February, the P-51B-1 was nearly complete, save 1650-3 engine; XP-51B#1 had been flown for two months and in the middle of solving the 'rumble isssue'.

By the time the P-51A was operational in CBI, the P-51B-1 was also beginning in combat ops in ETO.
 
Another problem, which would apply to both Merlin engines and Lee Enfield rifles would be that you have multiple shops manufacturing them. Shop A subcontracts to Billy Bob and Cousin Elmo's machine shop. The bolt does not fit. Shop A works with Billy Bob and Cousin Elmo and perhaps they ship them some receivers. BB&CE work out a solution. Meanwhile, Shop B subcontracts to Amitkumar and Cousin Ramesh's machine shop and the bolt does not fit. This time, Shop B sends bolts to A&CR's shop, and they figure out how to make matching receivers. Both guns reliably shoot .303 ammo. Are the bolts interchangeable?

Drafting standards have improved dramatically since WWII, largely because of WWII. Now, I can prepare drawings of gun and/or engine parts that precisely define the parts I need. Obviously, it helps if I understand what I need.

If you want consistency and interchangeability, you want to manufacture everything in one plant. On the other hand, if you want lots of something, you need another factory. This is especially true if you factory is within bombing range of damn foreigners.
 
Dave - While everything you say is true, the A-24 was already recognized as too slow to survive in MTO/ETO. Army units were already adopting P-39 and P-40 to 'fast attack and recon' combined roles per new CAS doctrine . I am not saying that A-24 would not have been a lot more effective by using 'the Navy way' - just that it didn't matter in any theatre save SWP - Over water flights encountered far less flak than over land in MTO/CBI, much less fighter intercept.
 
The Ranger's SBDs sure delivered a great deal of hurt to Vichy French assets, both Naval and shore-based in the MTO.
 
Drgondog, I have your book on the P-51B, and the thing that surprised me most was that the prototype for the P-51D (with the bubble canopy and 6-guns) was flying before the P-51B's combat debut.
 
Drgondog, I have your book on the P-51B, and the thing that surprised me most was that the prototype for the P-51D (with the bubble canopy and 6-guns) was flying before the P-51B's combat debut.
True, good eye - but recall that both P-51D-NA and D-1-NT were crafted from P-51B-1-NA fuselage Spares. Both were hybrids, comprised of NA-102 and NA-106 designs, The actual NA-102 to be modified came 'as is & complete' and were staged side by side with The First P-51D Cockpit Enclosure, Sliding modifications, namely P-51B-1-NA 43-12102. The ONLY difference between the three ships is that the two Ds had D six gun wings.

If one follows the 'original Advanced Design for Production P-51D/E', via NA-106, they were planned to be NA-104 P-51B-5-NA airframe and 'bird cage' canopy with NA-106 six gun wing - and the planned break was 42-106539, with all new P-51B/D config but with new wing. USAAF and NAA changed their collective minds in March 1943 as the first P-51B-1-NA was emerging as production #1.

In September as all three ships were nearing completion, the AAF requested either 55 or 85 gal tank be installed. At this moment in time there was only Experimental Department/Fieldservice design for the 85 gallon tank - and zero kits released for NA-73-95 Field Service roll outs. P-51D-1-NT was held back, found that 85 gallon tank was infeasible and the 55 gal tank was installed. A it was being installed, the AAF decided that all production P-51B/C/D would have 85 gallon tanks and NA-106 (and NA-107) was wrapped up and folded into NA-109 and distributed to make more P-51B-10-NA beginning with 42-106540..

Lot of changes and decisions in September 1943. The 55 gal P-51D could have been in limited combat ops by March instead of June - but would have less range than the P-51B/C w/85 gal tanks - and about the same as the P-38J-15 with LE tanks.
 
"...it helps if I understand what I need." Unfortunately, a lot of people don't understand and some really bad drawings make it out to the shop. I have a cartoon somewhere of a supervisor rubbing an engineer's nose into a drawing on a drafting board and saying "Bad engineer! Bad engineer!" Someone in the background says "What a moron. Everybody knows you've got to catch them in the act."
 
It is not too small to matter it is to big to be taken seriously by anyone working in advanced science at the time. Your quoted date of 1893 is three years after Lord Rayleigh had done his experiment, which I did at school and I am sure many forum members did, dropping a droplet of camphor oil onto water covered in lycopodium powder, this typically estimates the size of a Camphor molecule as 1.7nanometers. As I remember my physics teacher telling me, the accuracy doesnt matter, at the time no one had any idea how big or small an atom or molecule was, if it is wrong by a factor of ten it was far too small for anyone to consider measuring with the methods they had in 1890. Johnson Matthey in London produced 30 bars of 90% platinum and 10% iridium and in 1889 bar number 6 was accepted as the closest to the prototype meter standard selected in 1799

The standard metre copy you describe when the USA took the metre standard was numbered copy bar no No 27, it deviated from the standard metre by 1.6 microns.

To summarise this part, while Angstrom was developing his Angstrom unit in the mid 1800s discussing measurements of 10 to the power minus 10 metres (10 to the power minus 7 mm) the world standards based on bars of metal couldn't produce reliable metal samples of a metre to better than 0.01mm, or 10 microns. In aerodynamics in the 1930s and 1940s companies like de Havilland and North American were discussing surface finish of 2 microns for polished aluminium and 5 microns for a good paint finish. Testing a paint surface for thickness and smoothness could induce irregularities or 1 to two microns. All of these measurements are below or in the ball park of the difference between the USA standard metre and the official standard held by in Paris by the Mètre des Archives).
As an inspector of 30 years working in metrology and other things I ca see the fundamental and unavoidable mistake made by the people concerned in the period 1799 and 1893, recognised by any person with a scientific background, can you?



Your point was made with respect to de Havilland ordering or supervising production of their Mosquito design in the USA. The Mosquito can stand beside the P-51 as being at the top of aircraft design. For choice of aerofoil, cooling drag regime and surface cleanliness and overall low drag design they are on par by their own route and path, they have almost nothing in common other than with the same engine both were approx. 30 MPH faster than a Spitfire with the same engine.
As a company de Havilland could build you an engine pre and post war, build you a metal or wooden aeroplane, they designed their own suspension for the Mosquito based on compressed rubber good enough to cope with massive overload on recon versions and also carrier landings. They manufactured propellers under license from Hamilton in USA, produced their own hydraulic and electrically actuated propellers even developed phenol-formaldehyde resins which were half the weight of aluminium for propeller blades. The notion that de Havilland could not cope with any metrology issues between USA and UK is just funny, in a very funny way. I really don't know where you get your ideas from.
 
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AP bombs were typically used against shipping. I fail to see what use a bomb with a 9% charge to weight ratio would be against oil targets. Better to use HC bombs against such targets. 2, 4, 8, or 12,000 lb HC munitions were routinely dropped on oil targets. The charge to weight ratio was 71% for the 2,000lb bomb. Lots of these were dropped by Halifaxes during the war.

Jim
 
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