What If the Lockheed chose a conventional layout for the P-38?

[wuzak]

I'm sure we have all seen the original layout sketches of the P-38.

https://www.secretprojects.co.uk/proxy.php?image=http%3A%2F%2Fp38assn.org%2FPersonnel%2Fimages%2Fsketch.png&hash=f45377fe8207f704cc13f131eb7b07e3

https://www.secretprojects.co.uk/proxy.php?image=https%3A%2F%2Fi.pinimg.com%2F736x%2F58%2F5d%2F34%2F585d34fec79e32451f8442b373066bb3--xp-proposals.jpg&hash=b64dd121e28e237be5631468e6f6ab41

Like the top left sketch/drawing in both these pictures.

Would performance have been the same?

Would it have been easier to get to production?

Any disadvantages to a conventional twin layout? Advantages?

 

[tomo pauk]

Cheaper, easier to produce, greater internal volume, easier to make a proper 2-seater, lightet.

 

[Shortround6]

Kelly Johnson and crew picked the best (in their view) configuration.

One does wonder, for instance, where the guns would have gone in proposals 1, 2 and 3,
Or what the armament in 5 and 6 would have been. The USAAC wanted a cannon but had yet to make up their minds which cannon (and caliber) it would be.

2 and 3 have two engines buried in the fuselage.

The designs are all idealized concepts without such nagging details as carb inlets, radiators/oil coolers or even the turbo chargers.

If we believe that No 1 is better than No 4 then we have to believe that Kelly Johnson and crew did their sums wrong. even if they swap the pilot/cockpit back to the leading edge of the wing and fill the nose with guns.

 

[GrauGeist]

#6 isn't a bad idea, Cessna did that with their O-2A and it was a solid performer. Of course it worked with two IO-360 H-6 engines - if they had tried to build it on a scale to accept 2 V-1710s, it probably would have been one of those "one-off" X-planes relegated to the dust bin of history.

#1 *may* have worked, but now you have a "heavy fighter" like the Bf110 or Ar240, which was a good idea on paper, not so much when put to the test.

 

[wuzak]

#1 *may* have worked, but now you have a "heavy fighter" like the Bf110 or Ar240, which was a good idea on paper, not so much when put to the test.

Would #1 be any bigger or heavier than the actual P-38?

 

[GrauGeist]

Would #1 be any bigger or heavier than the actual P-38?

Hard to say.
As it was, the P-38's wingspan was 52 feet, the closest that matches that span, is the Bf110 and Me410 (both 53 feet).
The Ar240 was almost 44 and the KI-45 was 49.

 

[FLYBOYJ]

When I worked at Lockheed in the early 80s I heard Kelly Johnson speak several times at Management Club meetings. Regarding the P-38, he said his instructions from Hal Hibbard (the then head of engineering) was to meet the AAC Circular Proposal X-608 requirement. They felt that a twin engine aircraft was able to do this and chose a twin boom design to fit everything required (engines, turbos and installation components) while saving weight. I remember him saying that there were certain guidelines they were required to follow, one of them was a yoke installation instead of a stick which he would have preferred. Lockheed management never expected to build more than 70 aircraft when the P-38 was first designed.

 

[eagledad]

Gentlemen,

IMHO, designs 1, 2, and 3 would need some rework, as it appears that there is limited (no ?) rear visability. That might have been OK given the specification (intercept bombers, hopefully unescorted) but would have limited its usefulness in air to air combat. Design 5 actually saw the light of day as the SM 92 (first test flight November 1943) and Bf-109Z (no flight test). Design 6 reminds me of the Fokker D XXIII, test flown in June of 1939. Neither of the 2 prototypes had the performance of the P-38, but to be fair, the D XXIII only had 2 525 hp engines, thoight the SM 92 had 2 1250 hp engines.

Kelly Johnson certainly was an inspired designer.

FYI

Eagledad

Source william Green Warplanes of the Third Reich, and Fighters of WW II volumes 2 and 3

 

[Thumpalumpacus]

Kelly Johnson and crew picked the best (in their view) configuration.

One does wonder, for instance, where the guns would have gone in proposals 1, 2 and 3,

Belly-tray? Or, on 2, wing-mounted close inboard -- ammo supply belt-fed from the fuselage?

Or what the armament in 5 and 6 would have been. The USAAC wanted a cannon but had yet to make up their minds which cannon (and caliber) it would be.

On 5, the armament could have been between the fuselages, but perhaps problematic for lining up from an off-center pilot?

On 6, it'd have to be wing-mounted (at the head of each tail-boom, feeding ammo from outer wings and fuel from inner?), which introduces harmonization into the equation, or else synchronization, reducing rate of fire. Aerodynamic as all-get-out, but more complication in terms of mission.

2 and 3 have two engines buried in the fuselage.

Just what a front-line fighter needs, more complication.

 

[GrauGeist]

Along with the Bf109Z, Messerschmitt was looking at producing the Me609, which was to have been built from Me309 components but as the war drew on, it never left the development stage.

As far as Kelly's design, the Italians and Jaoaneae had similar designs, the SM.91 and Mansyu KI-98.
In regards to the SM.91, there were several "P-38 sightings" over Italy that have been waved off as myth, because the one P-38 that the Italians captured had been grounded and no Allied P-38s had been operating in the area around the time of the sightings.
I'm fairly sure that what was being seen, was the SM.91 during one of it's many test flights.
The one difference about the SM.91, was that it was larger, close to the XP-58's wingspan.

As far as #6's weapon mounting, look to the O-2 or even the OV-10's configurations, since their profile was identical.

 

[Thumpalumpacus]

[...] because the one P-38 that the Italians captured had been grounded and no Allied P-38s had been operating in the area around the time of the sightings.

Is that the one Caidin said was used by a jilted lover against the Americans?

Sorry for the dumb question, I get my soap-operas mixed up.

 

[GrauGeist]

Is that the one Caidin said was used by a jilted lover against the Americans?

Sorry for the dumb question, I get my soap-operas mixed up.

Not dumb at all - Caudin's fantasy love story has a grain of truth: the Italians did capture a P-38 and it was even used to attack a B-24 once.
And it was not sneaky, masquerading as an American, it was clearly marked in Regia Aeronautica markings.
The P-38's life as an Italian was short-lived, though. The engines were trashed by their low octane fuel, so it was grounded not long afer it's capture.

 

[Thumpalumpacus]

Not dumb at all - Caudin's fantasy love story has a grain of truth: the Italians did capture a P-38 and it was even used to attack a B-24 once.
And it was not sneaky, masquerading as an American, it was clearly marked in Regia Aeronautica markings.
The P-38's life as an Italian was short-lived, though. The engines were trashed by their low octane fuel, so it was grounded not long afer it's capture.

So the usage was done, but the soap-opera "back-story" was horse-hockey?

Classic Caidin, in other words, lol.

He's like the screenwriters for the movie Titanic. My son's mom and I went to see that on release. I'd already read Lord's book about it, and other stuff too, so watching the movie I was nonplussed by the writers' apparent need to "add" drama to a disaster that had so much drama already.

What's with these assholes? Sometimes reality is just more dramatic than your "creativity".

Where's my shotgun, these guys need off'n my lawn already!

 

[GrauGeist]

Hence the term "Caidinism".
He started out his career as a "historian" when he was an editor for an aircraft periodical in the 1950's.

Do a Google image search for "Col. Tondi P-38" and you be able to see that particular P-38.

 

[Thumpalumpacus]

Hence the term "Caidinism".
He started out his career as a "historian" when he was an editor for an aircraft periodical in the 1950's.

Do a Google image search for "Col. Tondi P-38" and you be able to see that particular P-38.

Any others interested:

I laughed, even as I read that tale, at how tall it read even on the printed page. Like a barroom BS artiste, Caidin clearly had no idea how his writing came across to the reader.

 

[tomo pauk]

#1 *may* have worked, but now you have a "heavy fighter" like the Bf110 or Ar240, which was a good idea on paper, not so much when put to the test.

Bf 110 have had ~35% greater wing area than P-38, wing of ttc of 18% at root (vs. 16%), and was a all together bigger heavier aircraft. Wing profile '2R' was used last on the Ki-61, vs. the NACA 230 series just being used on actual aircraft by the time P-38 was mooted.
Closest 'classic' size-wise to the P-38 was the DH Hornet - 2-engined piston-engined fighter that gotten everything right, but missed the crucial thing: timing.

Would #1 be any bigger or heavier than the actual P-38?

Probably not.

 

[don4331]

1st post so don't flame too badly.

The requirements from specification - X-608:
twin engines - X-609 is the equivalent specification for single engine
1k usable payload - flushes out to 2 - 0.3" M1919, 0.5" M2 (200rpg) and a 23mm Madsen cannon (50 rounds)/25mm Hotchkiss (Just cannon was specified in requirement, but the those were leading contender to be designed around).
Tricycle gear (for bonus points)
360 mph @ 20k'
fly at full throttle for an hour.
take off & landing with 2,200' over 50' obstacle.
Allison's new V-12
Turbo super chargers - they were going to be need anyways.

Allison V-12 with mechanically supercharged made 960hp on 100 octane fuel at 12k' in '37 when the Lockheed team started the design. RR Merlin basically made same 950hp at 11k' on 87 octane fuel, but is down to less than 800hp by 20k'; Allison loses power faster as it is less efficient. (Just 2 yrs before Merlin was only making 740 hp at 12k', but Rubbra and H**ker increased the supercharger efficiency from 36% to mid 70s. I can't but wonder if Allison, General Electric, Pratt & Whitney, Wright, etc didn't benefit from RR technology to improve their superchargers as they seem to also make some dramatic improvement without any formal recognition). With turbosupercharger, there was ability to cool the compressed air between the turbo and mechanical supercharger, so setup in XP-38 makes 1,100 hp (engine would actually make more but the radiators couldn't handle any more). So, your design is going to have to fit engine and turbo in close proximity. You also need to find some location for main landing gear - again ideally in close proxity. Engine is largest single mass, so if landing gear is any distance away, you will have to add structure - read weight. So, you aren't going to get DH Hornet short nacelles if engines are in wings. Also, in '37-39, the Meredith effect isn't know, so no leading edge/Mustang radiators, heck not even the YP-38 podded ones. Burying the radiators in wing ala Westland Whirlwind leaves no space for the >400 gallons of fuel in wing, if you're putting it in central fuselage, you're making it big = heavy/lots of skin drag. So, a "conventional" twin doesn't happen. Strike figure 1.

The armament requirement, specifically a cannon like Madsen. At ~115lbs for gun only - which means about 175lbs with all accessories (muzzle brake, trigger, etc but not ammo). About 10% heavier than HS.404 for reference. So, we definitely don't want to pack 2. While a belt feed was available for the Madsen, the 50 round drum is the most common configuration. So, if we attempt a P-82 layout, we will need to install it in center of the inter fuselage wing, and we will have an UGLY, not aerodynamic lump for the breach/feed mechanism and probably another for the drum magazine e.g. Spitfire with early HS.404. And we still need to figure out how to make the P-82 configuration tricycle gear. Strike figure 5.

The Allison engine isn't designed for cannon to fire through hub ala DB 601/605/603, Jumo 210/211/213 or Hispano Suiza 12Y engines, so a Dornier Pfiel/Fokker D.XXIII/Bolkhovitinov Sparka/Kawasaki Ki-64 configuration isn't happening. But something like the Bugatti Model 100 would certainly check the boxes. P-75 had cannon thru the remote gear box along with 4 - hmg, just install engines in tandem rather than the W-3420 of the P-75. Raising the cockpit to fit tricycle gear helps with rear visibility, not a bad trade off if you need the bonus point. Probably a very nicely looking aircraft possible - and they say if it looks nice, it flies nice. Probably better than historic - fewer joints for interference drag.

Options 2 and 3 are possible, and Allison certainly had no concerns with remote propellers - P-39 Aircobra, P-75 Eagle, B-42 Mixmaster. There are some issues with packaging which add weight but nothing insurmountable. I consider pilot in nose a preliminary design, putting between engines ala Ki-64 or behind like Sparka are possible.

The wing for P-38 is a plagiarism of that just designed for the Constellation Excaliber - same basic root and tip profiles, just a smaller planform and root a little thinner. Saved a ton of design calculations. Size of wing is based on loads of all components, which don't really change in any of the scenarios, so wing won't change significantly.

Bf.110 started flying with 600hp Jumo 210s - needing more wing area to fly at same weight isn't surprising. Messerschmidt's Zerstorer needed as re-wing like the 109 received between E & F models, between the B (Jumo 210) and C (DB601) versions - they were strengthening and aerodynamically cleaning it up anyways.