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The concept was sort of an "essentials only-type" fighter plane. Guns and that's it.
They wanted to do the smallest package possible, so it was developed from the standpoint of a "formula 1" type of race plane, modded for military use.
It was to be powered by a small V-12, thus the reason for setting the pilot so far back.
They promised "500 cubic inches, 500HP", but that version couldn't be developed in time, so a lower (350) HP version was used for testing instead.
Performance suffered because of this and the plane was passed up for that reason..
...or so I've heard/read
Elvis
I know you start with a "requirement" issued from the government, but if you want a plane that can be delivered on time and in quantity, you'd better start your program to FILL that requirement with a power plant that you know will be there.The proper way to do it would be to start with the paylad (weapons) desired and the performance that is wanted.
As in " we want a 1000lb weapons load to go 350mph at 20,000ft and climb to 20,000ft in 8 minutes. Range to be not less than 500miles at 200mph. Landing and take-off speeds to be compatable with standard existing airfields. Design Structural strength is to be 'X' Gs positive and 1/2 'X' Gs negative with an ultimate strength of 'X'+50% to be equiped with standard instraments and radio YYY, etc."
Designer then tries to figure out what engine and what sized airframe will give the desired performance. Sometimes the lowest price will also enter into it.
In some cases it took a second engine choice to make the airplane work (both Zero and Hellcat).
It has been said that combining a new airframe with a new engine is a recipe for failure
I know you start with a "requirement" issued from the government, but if you want a plane that can be delivered on time and in quantity, you'd better start your program to FILL that requirement with a power plant that you know will be there.
I'm not saying that these things never ever worked out. The M.B. 2-5, the entire hyper-engine project (XP-55, 49, 67), P-75, XP-58 are all designs that suffered at the hands of experimental engines.Like the above mentioned Zero and Hellcat?
Both prototypes used engines that were in production yet didn't deliever the required performance and had to switch to another engine.
Or the FW 190?
Engine it was designed for never made it into production.
P-39, P-40 and P-38 were designed around an engine that had at least passed a type test even if it wasn't really in "production". 7 engines delivered in 1937 and 14 in in 1938.
Or the Hawker Typhoon/Tornado design started with the Sabre, the Vulture was added early in the design proccess, first flew with the Vulture but we all know how that engine turned outLater proposals include 3 additional engines, one of which was the Bristol Centaurus. THe last made it to hardware stage on the Tornado airframe. Strange that the final fighters produced of this family used the Centaurus.
THis is just fighters somewhat of the top of my head.
Some goverment requirements specified which engine was to be used.
maybe confusion with the vague and mysterious Tucker XP-57?Some mistakes can be pretty obvious. Like one book claiming the plane was to be armed with two 20mm cannon and two .50cal MGs. Nobody else makes such a claim and trying to figure out were the guns would go makes it pretty clear that this is a mistake.
I still say you never go with lesser engines. it's a waste of production capacity. "Cheap" Aero engines are still too expensive and the workers building them need to work on real engines.Possiable but book devotes half a page of text to the XP-57 and a full page 3 view drawing.
Gives two armament options for the XP-57.
Almost a full page of text to the XP-77, a full page 3 view and 3 photos.
Yep, I think that's the best approach.ClayAllison said:Building a light fighter is great, just make it the lightest package you can that has everything you need, like the Zero and the Ki-43.
Going from therory to practice always has a few problems.
Given the usual + or - of a few % in both individual aircraft wieght and engine power due to production tolerances comparing the results of just one set of numbers and declaring the therory bad doesn't seem to fair.
It's 100% true, i always knew that. It's why it's so tiresome ans uselessness to compare aircraft performance datas.
http://www.ww2aircraft.net/forum/aviation/late-war-fighter-competition-20794.html
Now try to explain it to your friend Soren, einmal!
Not only them, it'an universal problem. It's why it makes sens only if you compare with the Yak-1 you have modified. And with some approximation (40kmh~25mph).Especially considering the Russians seemed to have a fair degree of trouble just getting their production planes to perform up to prototype standards. Just which Yak-1 is being compared?
Early Yak-1M, did not recieved it's wing tunnel radiators at time, and was tested without them AFAIK in february-march 1943, keeping the Yak-1 one. But there is a discuss about that from specialists...It's true, the Yak-1M "dubbler" was flying faster, 656kmh insted of 638, than our's first Yak-1M.Were there anyother changes to the plane that might change the drag, like different oil cooler location or ducting, a different propeller and/or spinner or other modifications besides a better fit and finish on the Prototype Yak-1M vrs a series built aircraft?
I'm not sure, since the La-5 with the more sturdy and big wing gained only 80 kg from that. But it's true that all proportions keeped, a 8% smaller wing should be 26% lighter. It makes 420 - 440 kg from 530-560kg weight reduction.Doesn't take a lot of genious to replace the wooden longerons with metal ones as the metal became more available later in the war. According to one book this accounts for over the half the weight difference.
It worked elsewere, with due reservation of course:
109F/109E.
Il-10/Il-2
D-550/D-520
Anyway, you could turn your problem as much as you like. To overcome the 109F, from the P-40 you have to make a plane smaller and lighter, with some sacrifices in weapons, range, protection matters. Or use a powerfull engine that not exists.
It's much more difficult to gain on the Cd, even impossible.
Regards
Shortround6,
Thanks for clarifiying your sources.
I see what you're getting at.
Yes, definately some descrepencies.
As for testing an engine rated @ 12K ft, at 4K ft., I've heard many times, from different sources, that the engine that was supposed to go in the XP-77 wasn't available at the time testing was scheduled, so they went with a less powerful version.
The jist I got was that it was hoped that the more powerful engine would be available by the time testing ensued.
That could explain why the plane was tested at the lower altitude, although, that does seem like a really low test altitude.
Weird.
Elvis
It worked elsewere, with due reservation of course:
109F/109E.
Il-10/Il-2
D-550/D-520
Anyway, you could turn your problem as much as you like. To overcome the 109F, from the P-40 you have to make a plane smaller and lighter, with some sacrifices in weapons, range, protection matters. Or use a powerfull engine that not exists.
It's much more difficult to gain on the Cd, even impossible.
Regards
Actually as far as the 109F/109E goes there were a number of differences that would affect drag besides the wing.
I am not sure about the IL-10/Il-2 but in the D-550/D-520 comparison the D 550 used a diifferent engine (higher power) in addiation to a few other changes, like a retractable tail SKID instead of a tail wheel.
For a P-40 to best a 109F you need to do both.
Make the P-40 smaller and use a more powerful engine that did not exist at the time.
Shortround,According to most sources the engine they hoped for was supposed to give 500-520hp at 27,000ft.
The engine they fitted was supposed to give 520 at 12,000ft for one minute.
Unless they got a dog. It was a standard Navy engine fitted to the Curtiss SO3C if I have things right.
What effect do you think the undercart arrangement is going to have on this? Or are we re-doing that as well?What about laminar flow wings?
See the idea of installing a V-1710 with an auxillary stage supercharger has been discussed already.
To save weight I suggest removing two of the six .50 guns. Each gun weighs 70lb, one round 0.3lb. With 235 rounds per gun that saves a total of 280lb. What about laminar flow wings? C&W had designed some for the XP-60.