P-38 (no turbo) vs. Fw-187 (with DB engines)

[stona]

As far as armament goes you've really answered your own question. Many of the images we have are of prototypes or even mock ups and bear little or no relation to the armament that may (or may not) have been fitted to any production versions.
This is always the problem with the Fw 187. With the exception of a few A-0s, which qualify technically, there were no production aircraft to compare with the P-38 or anything else. This exasperates the promoters, detractors and even the neutrals in equal measure. It always promotes arguments which produce far more heat than light.
Cheers
Steve

 

[tomo pauk]

There is always a problem when taking into consideration factory or designer's data about proposed versions. Lockheed was expecting 431 mph at 21000 ft for the P-38 with two Merlin XX engines. Loaded weight 14500 lbs - the Merlin XX was some 100-140 lbs heavier than single stage V-1710s; no turbo on this proposal. The estimate lists 1170 HP at 21 kft (and we can add about 150 HP from exhaust thrust? - 1300-1350 HP total?). We know now that early P-38s were hard pressed to make 400 mph with 1325 HP at 20000 ft, and that would make Lockheed's estimates at least 20-25 mph over optimistic.

The 'mid-alt' P-38 would've avoided some of the P-38 issues, like hi-alt compressibility problems and freezing cockpit. It would still be, for a fighter, easier to spot recognize than other Allied fighters, roll rate problem would still be there, and still it will be the airframe with some blind spots. Fw-187 would also share some of those issues - anybody has data about wing thickness shape? For the P-38 again: messy cockpit; only one generator per A/C, until that gets rectified along with other issues.
Performance, depending on the engines, should be from 370 to 400 mph between 15-20000 ft with single stage V-12s - more than enough for Asia-Pacific, and sufficient for MTO from Op Torch on? Should be cheaper easier to produce than turboed P-38. Much more expensive than P-40 or similar crate, but at least it should climb a bit (despite heavy weapon battery and plenty of ammo) and have superior combat radius.
High alt performance, necessary for ETO tasks, would be good only with Merlins, at least until Allison introduces it's 2 stage engine.
Having another source could enable having both turbo and non-turbo available in good numbers?

 

[Shortround6]

A non-turbo P-38 will climb better than a P-40 using the same engines. How much better is the question.
A P-40C with no drop tank goes about 7500lbs
A P-40E with no drop tank goes about 8300lbs
A P-40F with no drop tank goes about 8675lbs

P-38 has a lot more fuselage but only has 39% more wing. It may have around 54 % more drag at medium speeds?

 

[tomo pauk]

The P-38 (what version?) have had the equivalent flat plate = 8.84 sq ft, or 4.42 per engine. P-40 (early?) was at 5.71 sq ft. So one engine of the P-40 has to pull 1.3 sq ft more of 'drag' than what is the case for the P-38. The drag during the climb would include also the induced drag.

Hopefully Bill M. could drop a line or two about this arythmetics

The weight question - Lockheed's proposal gives 14500 lbs for the version with Merlin XX (loaded weight), while the early P-38s were at basic weight of ~13000 lbs, and at 15500 lbs with full load (protected 300 gals, ammo etc), clean. It is not unrealistic that a turbo-less V-1710 version goes at a around 14500 lbs, Merlinized one around 15000 lbs? That would make it 7250 lbs per engine (vs. 8300 lbs for the P-40E) and 7500 lbs (vs. 8675 for the P-40F). 1000+ lbs (more than weight of internal fuel tankage of many P-40s) per engine would be quite a difference for 1100-1300 HP engines.

 

[Juha]

Apart from the initial 2 seat night fighter variant the zerstorer variants these evolved into were engineered with a raised canopy and Me 410 cheek guns, the Fw 187C also was to have fixed rear armament aimed by periscope. Rear arament shows up repeatedly in various proposals and engineering mock ups illustrated or photographed in the Dietmar Hermann book. Hermann is not your average aviation author and tries to show relevant technical detail, he interviewed Hans Sander, who was a test pilot on the program.

Despite this the Fw 187 was always lighter and much faster than it competitors and it did so on engines that were actually available and reasonably well developed. Some 26000 hours of direct engineering time from some of Germanies finest engineers went into this aircraft for no result. Repeated modification requests attempted to turn it into a sort of multi role combat aircrsft loaded with equipment.

This was a failure of doctrine or procurement or managment. The aircraft that ended up doing the role of the Fw 187 were the Ta 154, Do 335, He 219 and to an extent the Me 410. All needed not only new large engine but developed versions of these engines that provided around 2200hp rather than the 1750hp the Jumo 213 and Db603 entered service with. Granted the were available in mid/late 1944 but by then couldn't be put into mass production and further delays resulted from C3 fuel shortages.

I was refering on built a/c not on projects or mock-ups.

 

[Juha]

Obviously there was no reason it couldn't be uparmed as it was with the later prototypes. Also understand that most first prototypes had no armament installed, so its odd that it had any guns at all.

Not much use to built a proto with 2 mgs if the idea was to produce an a/c with 10 cannons and 5 mgs. Smith book is an oldish one and I have given only a brief browse on Hermann's book when it was published, so I cannot say how reliable the Smith's info is but he claimed that Fw 187 was offered to the RLM as a "light" fighter, so according to him the light armament was one feature of the design.

Juha

 

[stona]

Smith is correct in that the Fw 187 was developed independently by Focke-Wulf and then offered to the RLM as something it might be interested in. It was interested, and a development contract was offered by the RLM to Focke-Wulf, drawn up to Focke-Wulf's specifications.

I've never seen it referred to as a light fighter. The armament was the equivalent of the Bf 109 in the early 1936 mock ups. Focke-Wulf claimed that there was always an intention to increase this on the Fw 187, as indeed happened with the Bf 109 with the introduction of the gun wing (we'll draw a discreet veil over the unsuccessful centreline machine gun attempted by Messerschmitt).

Since the Fw187 was effectively killed off by the RLM as a long range single seat air superiority fighter it was reborn as a heavy fighter, though once again with forward firing armament similar to the contemporary Bf 109. This comprised two MG 17s and either two MG FF or two MG 151s. One version was two have four MG 17s and two MG 151 cannon.
There was also provision for a rearward firing MG 81 to be operated by the second crew member.

It is easy to see why the RLM was so reticent. It already had the Bf 110 in production and another two engine aircraft lifting a similar weapon load as the single engine Bf 109may have appeared to make little economic sense.
The same argument was made in Britain regarding the Westland Whirlwind which lifted four cannon, the same as the planned 'Hawker fighter', which became the Typhoon, could achieve with one engine.

I don't think that the RLM bought the more optimistic performance claims made by Focke-Wulf. It knew that prior to the Fw 190 the company was in desperate need of a decent contract and might well be less than careful with some of its theoretical projections.

Cheers

Steve

 

[Juha]

Hello Stona
rereading Smith's book, I cannot find the notice of the "light fighter" (from where I read that last night?). He only writes that 187 originated from Tank, who began to develop a fighter which would possess a performance superior to that of any other a/c then envisaged and that was behind the idea of twin-engined single-seater. Tank counted on that the exceptional characteristics of the a/c would convince the RLM to order the plane. According to Smith the instigation of Udet was behind the decision to convert 187 V3 into a two-seat. Udet had just succeeded von Richthofen as head of the Development Section of the RLM's Technical Dept. and was convinced that a twin-engined interceptor could never possess the manoeuvrability of a single-engined a/c, and he therefore asked Tank to mod. the Fw 187 as a two-seat Zerstörer.

On the rear gun, if 187 A-0 carried one it must be oneof the poorest rear gunner position in 1939.

 

[stona]

On the rear gun, if 187 A-0 carried one it must be oneof the poorest rear gunner position in 1939.

Mounted over frame 13 with +15-60 degree vertical movement and 30 degrees left and right horizontally. It was supplied with 1,000 rounds of ammunition, the weight of which is usually overlooked by the proponents of the type (as is much other equipment needed on a service version).
It was certainly a very cramped position.
Cheers
Steve

 

[spicmart]

What were the advantages of a Tigercat compared to a navalized P-38. Why did they not just went this way instead of creating a whole new design?

 

[FLYBOYJ]

What were the advantages of a Tigercat compared to a navalized P-38. Why did they not just went this way instead of creating a whole new design?

The P-38 was never intended to be a naval aircraft for starters. As a matter of fact no one ever thought that more than 70+ P-38s would ever be built. I think there were some artist depiction of a navalized P-38 but that was someone's marketing plan.

The Tigercat was designed as a naval combat aircraft from the ground up. Entirely different design requirement for an entirely different customer.

 

[Shortround6]

I would also note that the F7F was designed/intended to operate from 45,000ton carriers (the Midway class).
The F7F was a much bigger plane than the P-38 and the early ones went over 21,000lbs clean.

 

[spicmart]

Talking about high performance twin-engined fighters. Did the P-38 ever had the potential to get to the performance level of th Hornet or Tigercat?

 

[Shortround6]

only if you changed the wing.

 

[spicmart]

only if you changed the wing.

Thanks. But could you elaborate?

 

[Shortround6]

At certain altitudes the P-38 was operating only a few dozen mph from it's compressibility limit. The Hornet and the F7F both had level speeds (at certain altitudes) above the compressibility limit of the P-38. You can see the problem with trying to push the P-38 to those speeds even if you had the engine power.

 

[swampyankee]

The P-38 was a considerably older design than either the Tigercat or the Hornet.

(edited to add...)

So it was unlikely to be able to match the performance, over a broad range, of either aircraft, although it may be better in some restricted parts of the flight envelope.

 

[pinsog]

Someone has said the XF5F Skyrocket showed how NOT to build a twin engine carrier based fighter. (I personally don't agree with that and think it was a huge missed opportunity) So they designed and built the F7F Tigercat that fixed all those things that were wrong with the XF5F and ended up with a carrier based twin engine fighter that couldn't actually operate from a carrier....(I actually love the Tigercat)

I can't see the point of a non-turbocharged P38. The reason for the long booms was specifically to house the turbochargers, intercoolers etc. if you are going to do a non turbo twin you should start with something else and ditch the twin booms and associated weight and drag.

Why not hang a pair of Merlin's under an XF5F Skyrocket? It was tiny compared to a P38 being 10 feet shorter and 10 foot less wingspan. 303 square foot wing, plenty of room for internal fuel.