Improve That Design: How Aircraft Could Have Been Made Better

[Zipper730]

Regarding the "Shortnose P-37"

I believe it was under the nose or under the centre wing area. Hard to tell.

Understood. I'm curious if any other members, such as drgondog P pinsog S Shortround6 tomo pauk T tyrodtom would have anything of use...

Until I get anymore information on that, I was thinking about some other ideas.

 

[pinsog]

I had thought of taking a P36 and moving the engine forward just a bit if needed, removing the cowl guns and putting a turbocharger behind the engine. But I keep thinking about how those engines sling and leak a lot of oil and the problems a hot turbocharger right behind that might cause. Be a nice tight power pack if it could be done.

Any thoughts on that setup?

 

[wuzak]

The regular intake didn't suffer from ingesting oil, so that wouldn't be a problem.

As far as oil hitting the turbo, I'm guessing it would be a very small amount and probably in a very fine mist. If it was going to be a problem you could put a guard around the turbo to prevent the oil getting on the hot bits.

 

[John Frazer]

As s panacea, to make any of them better, or replace them with something different in only one thing, replace some/most of the fuselage with lifting body.
Instant increase in range/ speed &/or payload.

Simplest from the Eshelman patents, is practically a very large fillet. Shrink the non-lifting fuselage down to a pod for pilot & engine, and a boom projecting the tail aft.
Increase the center span to huge chord & camber, housing everything not in the wings.
More marked is the Burnelli, which can be extended into a huge bomber or transport, or maritime/ASW plane.

Some have made the mistake of calling Burnelli type things a sort of all-wing or the media term flying wing. Nope. Simply eliminating or replacing non-lifting drag.
Anything from a fighter to a transport benefits, and there's no doubts about controllability or instability as with a tail-less fin-less all-wing.

 

[John Frazer]

Higgins-Bellanca 39-60
Transport, 1944

Clare K. Vance, 1930s 7500NM range

Arado maritime / bomber E-470
"F" model with jets, "America bomber

Antonov LEM-2

De Monge, before going to work for Bugati on their "blue" racer, worked on the stupendously ugly planes built by Dyle Et Bacalan

Northrop Avion1 "216"

All show that the ideas were known.
Only lack of support stopped them. (and in some cases, the start of the war, in others, the end of it)

Design mechanics of any particular iteration might have troubled some, but the design concept was sound.
The Kalinin giant 8-engine K-7 comes to mind.

 

[Zipper730]

Davis Manta

It was a long-ranged fighter proposed by David R. Davis revolving around the fluid-foil he designed, but with a manta-ray planform with an aspect ratio in the range of 6.0-6.5. Two configurations were proposed, one of which was a tractor-prop design and a single fuselage; the other was a twin-boomed design with a contra-rotating pusher-prop. Both had a nose-gear, a raised-up cockpit/canopy, provision for four 20mm cannons and four 0.50" machine guns in the wings. It appeared to be powered by an Allison V-1710 with turbocharging.

While the aircraft was fairly large, at 26" longer than the P-38, though it's wingspan was 24" less, the empty weight might have been less than expected owing to the aircraft having a blended wing/fuselage configuration which can produce greater strength to weight, though I never saw a weight figure published for the aircraft design.

These are some pictures that were published...





While there were clearly some problems with the design, such as the fact that the V-1710 would almost certainly never have delivered the 430-440 mph requirements specified, something only further confirmed by the fact that the wind-tunnel model supposedly "disappeared" when Davis fell under investigation: Much of it could potentially have been fixed with more powerful engines, of which the H-2470 and V-3420 appeared able to deliver the desired performance, taller landing-gears, and bigger propellers.

An artist named Justo Miranda had done an artist-conception of this design powered by an V-3420 (possibly under the misconception that the aircraft was to be powered by the V-3420 instead of the V-1710), which depict both proposals.



The following members might have some insights I don't have

drgondog , P pinsog , S Shortround6 , W wuzak , X XBe02Drvr

 

[Zipper730]

Another design that I had some interest in would be the XP-54: Of all the R-40C designs, it had the most potential in terms of being a workable design. It had a method for cockpit egress and avoiding getting turned into ground-meat from the propellers.

It seems the problem was that it got too heavy, and I'm curious why.

 

[John Frazer]

Then there are the more nearly all-wing (with fin/rudder, but without tail or separate stab/elevator. (Google translates a German site as calling such a thing "brush-less")
Still frequently called by the media term "flying wing" but disdained by all-wing purists because they had rudders.
Note that to this day, not a single all-wing sort without that fin/rudder &tractor prop have failed to make a workable plane that wasn't highly risky experimental, "not ready for consumers". This goes for the Hortens, despite a few sport gliders of their sort, Northrop, the B-2, the present-day Horten HX-2.

Most designers of such things wanted to make big planes, with everything inside, but with tiny test planes, they had a "fuselage-ish" pod for the engine in front and the pilot. All tried tail-less and failed, as with wing-tip fins. All but the Hortens and Northrop settled on tractor prop with the fin/rudder right aft in the prop- blast, and made functional utility planes.

Cheranovsky succeeded with the BICh--3 & 7a, Fauvel similarly with the AP-10 and later AV-36 sport gliders (several up to the present day flying, the little "Pelican" a derivative). The Arups were apparently entirely brilliant successes, and Canova made a good aerobatic glider before losing support to make a plane. Payen for Aubrun built one like the Arup/Hoffman with very low aspect ratio before moving on from something the "markets" studiously ignored.
Moskalyev made a successful little test plane with even more of a distinct fuselage half in the wing, ignored.
All these were well before the war, some stopped by it. The Eshelman "Spirit of National Defense" ("flounder") and the Lippisch dfs-39c (tractor & fin/rudder, discarding the little "canards") succeeded during the war.
Most seem to have had remarkable speed on little power, efficiency being the promise of all-wing.
Short aspect-ratio planes had their trick of using "parachute lift" to fly slowly while still being sleek & quick, the Arup/Hoffman sorts being stall/spin-proof while being nimble & quick.

 

[wuzak]

Another design that I had some interest in would be the XP-54: Of all the R-40C designs, it had the most potential in terms of being a workable design. It had a method for cockpit egress and avoiding getting turned into ground-meat from the propellers.

It seems the problem was that it got too heavy, and I'm curious why.

It got big!

An indication of how big the XP-54 was is that the centre fuselage was longer than the Spitfire, P-51, P-47, Tempest V, Fw 190D-9, Ta 152H and is only a few inches shorter than the P-38.

It's overall length was longer than the P-61, A-26 and Mosquito and only slightly shorter than a B-26 Marauder.

Part of the problem was the pressure cabin, which dictated the egress system.

Then there was using two 37mm M4 cannon and two 0.50" HMGs, and then needing a compensating mechanism so that the cannon and machine guns hit the same target. The original scheme was for all 0.50" HMGs or a combination with 20mm cannons.

The design was originally to have the XH-2600 (X-1800), then went to the XH-2470. It was planned to use the XR-2160 Tornado when that became available, so the structure to support that engine, which was heavier and more powerful, but also a completely different shape to the other engines. So the engine support structure was probably heavier than it would have otherwise needed to be.

 

[Zipper730]

It got big!

What factors drove up the aircraft's overall size?

Part of the problem was the pressure cabin, which dictated the egress system.

Why was the pressurization system a requirement? The P-51 and P-47's both flew at similar altitudes and didn't require it.

Then there was using two 37mm M4 cannon and two 0.50" HMGs, and then needing a compensating mechanism so that the cannon and machine guns hit the same target. The original scheme was for all 0.50" HMGs or a combination with 20mm cannons.

I thought the traversable guns was just something Vultee adopted on their own initiative...

The design was originally to have the XH-2600 (X-1800), then went to the XH-2470. It was planned to use the XR-2160 Tornado when that became available, so the structure to support that engine, which was heavier and more powerful

The H-2600 and H-2470 both weighed 2400 pounds, with the R-2160 weighing 2350. Power output varied by about 50 horsepower maximum. The reconfiguration of the engine mounts might have played a role.

Was there any change in altitude requirements from the earliest proposals of the XP-54 to the flying models? Also, what did the XP-68 proposal look like?

 

[wuzak]

What factors drove up the aircraft's overall size?

The requirements put on it by the USAAF.

Why was the pressurization system a requirement? The P-51 and P-47's both flew at similar altitudes and didn't require it.

Because the Army wanted it.

I don't know if the P-51 and P-47 could fly at high altitude for prolonged periods without detrimental affects for the pilot.

I thought the traversable guns was just something Vultee adopted on their own initiative...

The Army specified the armament and Vultee came up with a system to make it work.

The problem with mixing the M4 cannon with the 0.50" HMG was the difference in the trajectory. That is why the nose was built to elevate +3° to -6°. I believe the 0.50" HMGs were fixed and the M4 would be elevated to match the 0.50"s.

They had to come up with a computing gun sight to make it work.

The H-2600 and H-2470 both weighed 2400 pounds, with the R-2160 weighing 2350. Power output varied by about 50 horsepower maximum. The reconfiguration of the engine mounts might have played a role.

The R-2160 may have been about the same weight, but it definitely was (expected to be) more powerful. As much as 500hp more than the X-1800, and 200-300hp more

Was there any change in altitude requirements from the earliest proposals of the XP-54 to the flying models?

Yes, as well as many other operational requirements.

Also, what did the XP-68 proposal look like?

The XP-68 was the designation for the Tornado powered XP-54.

 

[John Frazer]

USAAC Test Results Sept 1939
Burnelli fighter / bomber X-BAB-3

From studies of the research made by the Burnelli Co., the NACA and the Air Corps, the Military adaptability of the basic design has the following advantages over the orthodox streamlined dead-weight fuselage.

1. The coefficient of drag is the lowest known for any useful airplane today.
2. The coefficient of lift is greater .
3. The lifting fuselage has distinct advantages for the installation of power plants, bombs, armament and all other accessories over the streamlined fuselage.
4. From wind tunnel tests already conducted by the NACA and NYU the performance is exceptionally good in every phase.
5. The design embodied extremely good factors of safety -- considerably higher than the streamlined fuselage type.
6. The design is simple of construction and in the opinion of the Air Corps lends itself to high speed production better than any design and therefore the valuable time element involved in all production contracts can be taken advantage of to its fullest extent.
7. It is apparently a cheaper airplane to build because of the time element referred to in 6 above.
   
   - - - - - - - - - - - - - -

This was submitted for what was to become the A-20.

Another, possibly related to the A-1 in the other color picture, above.

 

[Zipper730]

The requirements put on it by the USAAF.

I'm just surprised that the early design they were working on used an Allison V-1710 without a turbo. I figure they'd have wanted to get that turbo on the design with a vengeance, or adopt a twin-stage set-up, if they wanted high-speed performance (the best place to get it would be at altitude). After all, the P-40 only ended up with a single-stage supercharger because the turbocharged designs (XP-37/Y1P-37) didn't have enough visibility over the nose.

Because the Army wanted it.

Supposedly the design went from around 11000 pounds with a wing area in the 200-300 square foot range to 456 square feet, and weight went up to around 15000-19000 pounds when it was loaded.

I don't know if the P-51 and P-47 could fly at high altitude for prolonged periods without detrimental affects for the pilot.

Never heard anything to say it couldn't: The P-47 routinely operated in the 25000-30000 foot range and if you had no oxygen, you'd be dead in a matter of seconds or minutes. B-17 crews operated around 25000 feet a lot and they flew missions that were several hours in length. If anybody would have had detrimental effects, they would have been more likely.

The Army specified the armament and Vultee came up with a system to make it work

So they came up with this on their own initiative

 

[Zipper730]

Why'd the US Navy cancel the H-2470? Also, I'm curious if the USAAF could have taken over the funding if the USN cancelled it

 

[XBe02Drvr]

Why'd the US Navy cancel the H-2470? Also, I'm curious if the USAAF could have taken over the funding if the USN cancelled it

Jets were on the horizon.

 

[XBe02Drvr]

I don't know if the P-51 and P-47 could fly at high altitude for prolonged periods without detrimental affects for the pilot

Anybody who's had a chamber ride can tell you. Above FL 350-360 breathing 100% O2 with an ambient pressure regulator doesn't supply enough partial pressure of oxygen in the blood to stave off hypoxia, so pressure breathing becomes necessary, a very taxing and exhausting exercise. Above approx 450, ambient pressure is not enough to keep the nitrogen in the blood in solution, and it literally "boils" out, resulting in instant death by eruption. If you're going to operate in that altitude range or higher, you need pressurization or a pressure suit, or both.
I've flown a couple hundred hours at FL 250 in a non pressurized turbo 210 Cessna, breathing through nose bags, and let me tell you, though it doesn't feel hard at the time, by the end of the day, you feel like you've been run over by a train.
I can tell you that at 260, I was good for 45 seconds after the mask came off, before the chamber floor came up and kissed my face. And at 370, pressure breathing, I was first in a chamber full of tactical jet aviators to signal "uncle" and have the chamber brought down, after about five minutes. The jet jocks were a little disgruntled that I broke up their little "macho quotient" contest early on.
Cheers,
Wes

 

[Shortround6]

It was assumed by many in the planning departments/purchasing that the altitudes at which combat took place would keep going up. Which is why the Americans, British, Germans and others had designs/schemes for planes with pressurized cockpits all in the works in 1941-42. However, for a variety of reasons this did not happen with piston engines. At least not to the extent the planners thought.

There is a difference between what the human body will tolerate for 1 to 2 hours and what it will tolerate for 6-10 hours. You could strip down a Spitfire and send the pilot after a JU-86 at over 40,000 ft on occasion. You could not hang a bunch of drop tanks on a Spitfire and fly it to Berlin and back at 40,000ft and expect the pilots (or a large percentage of them) to stay healthy. Or to even stay combat effective.

Problems with guns, radios, instruments and even ignition systems on the engines kept the combat ceiling lower than expected in addition to the problems of keeping the pilots/crew healthy (or conscious) without pressure cabins.

Germans had pressure cabins in some early 109Gs, A number of the Bomber "B" designs had pressure cabins (at least to begin with) for example.

Americans had several designs for bombers with pressure cabins in addition to the B-29 and there were a number of fighter prototypes with pressure cabins.

But some of the problems took too long to solve and the war was fought (mostly) with unpressurized aircraft.

 

[Zipper730]

It was assumed by many in the planning departments/purchasing that the altitudes at which combat took place would keep going up. Which is why the Americans, British, Germans and others had designs/schemes for planes with pressurized cockpits all in the works in 1941-42. However, for a variety of reasons this did not happen with piston engines. At least not to the extent the planners thought.

What reasons? I just thought the issue had to do with specialized high altitude fighters.

I'm not sure what the projected service ceiling, critical altitude, and combat altitude the XP-54 was expected to fly at, but in practice they had a critical altitude of around 28,500 feet. This isn't much different than the P-51. The P-51's seemed to be able to routinely operate at 31000 feet during combat operations over Europe. I'm not sure how high they flew for B-29 escort.

Problems with guns, radios, instruments and even ignition systems on the engines kept the combat ceiling lower than expected in addition to...

The problems I can see with the guns are temperature related, as for the radios and instruments, I'm surprised altitude would have much effect. As for engine ignition systems, why would that cause a problem?

 

[Shortround6]

The guns were temperature related. You needed more heat to the guns to keep them operating.

Thin air is less of an insulator than thick air and both radios (which sometimes had 600 volts or more DC running through part of them) and engine ignition systems (thousand of volts) suffered from short circuits and engine cross fired, spark intended for one plug/cylinder jumped to another contact or wire and fired the plug in another cylinder at the wrong time. This caused rough running and loss of power.
This was solved on some engines by pressurizing the magnetos, some engines required special ignition harnesses. The problems were solved but it took time.

 

[swampyankee]

Jets were on the horizon.

R-2800 was already there, and the navy didn't want to deal with another liquid.