Could you have designed a better Warbird?

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Me thinks the only real problem P-38 had was availability in the time it was located in top 3 fighters of the world, ie. prior 1944.

Now about alternative engines for P-38...
There is (was) no need for it to wait two-stage Merlins. Single-stage, US-made Merlins were available in some numbers in late 1941, providing 1300-1450 HP, depending on boost applied. So we could expect a performance in late 1942 (squadrons in combat) to be as good as that of historical P-38J (late 1943).
Adding Merlins to the P-38 would've:
- avoided problems caused by British fuel to the turboed Allisons,
- the absence of turbo intercooler would've enabled more fuel to be carried,
- installation of the engine as a power egg (just like Beaufighter, for example) would've make the cooling system lighter more compact (= less likely to be punctured) and with another gain in space for fuel tanks.
Perhaps 3 cannon armament for RAF; 5 HMGs for the ones USAAF got?

Another engine that might have been installed in P-38 was Twin Wasp, either as mech-supercharged, or turboed. With turbo, my take is that performance would be as good as of pre-P-38J models - for slightly more drag we cut the weight of cooling system. Again, zero issues with Brittish fuel.
The two-speed two-stage Twin Wasp would offer more simplicity (lower price, more planes...), less weight - if additional fuel tanks are not added in lieu of turbo it's accessories. Above 15K it would be not as good as turboed versions though.
Attack/bomber version (mech Twin Wasp, 2-3 HMGs, in the place of now-deleted turbo, intercooler, coolant system guns ammo we mount fuel tanks) would've been nice - armed Mosquito...
 
Not much point to using that large / heavy / expensive P-38 twin boom airframe unless you need the space for turbochargers. With mechanical superchargers you could employ a lighter and more compact airframe similiar to the Westland Whirlwind.



Speaking of which....
I wonder if the somewhat similiar Fw-187 airframe could have been powered by a pair of 950 hp BMW132 radial engines? Power to weight ratio would be pretty good even with such small engines.
 

That doesn't follow at all.
1. First P-38F is delivered in March of 1942, First P-38G is delivered in June of 1942.

2. P-38Fs used V-1710-49/53 engines rated for 1325hp for take-off AND at 25,000ft. P-38Gs used V-1710-51/55 engines with the same nominal ratings.

3. The single stage US Merlins were rated at 1300hp for take-off, 1240hp at 11,500ft in low gear and 1120hp at 18,500ft in high gear. Any 'over' boosting that might raise the power only raises the power BELOW those altitudes.

4. Historically, " Merlins were available in some numbers in late 1941" was 45 engines total US production by the end of 1941. Granted production was ramping up fast with 109, 149, 333 and 505 engines built in Jan, Feb, Mar and April respectively. This compares to 6402 Allison's delivered by the end of 1941 and deliveries of 1,101, 1,179, 1,151 and 1,203 for the same four months.

5. While there were problems with the Allisons in the P-38Fs it had to do with the under sized intercoolers, the engines were down rated for a number of months and WER was never authorized for them (although units like the 8th fighter command used their own limits, 1325hp up to 20,000ft). The engines in the "G" had larger carburetors and other modifications and may never had had restrictions placed on them and may have had a WER rating of 1450hp at sea level. .

6. The bit about the singe stage Merlin (V-1650-1) powered P-38 offering the Performance of a P-38J is really off the mark. The engines in the P-38J had a take-off and military rating of 1425hp to 24,900ft or better and also had a WER rating of 1600hp up to at least 10,000ft.



It is not slightly more drag, it is a lot more drag unless you can move forward the knowledge of engine cooling and cowling by by 1-2 years.
After the first P-40 was built and flying they figured it had 30%less drag than the P&W powered P-36 by measured flight tests. While Radials git a lot better it wasn't until mid-late 1942 that ALLIED EXPERIMENTAL installations got to where they were about equal to liquid cooled engines. Add in 3-6 months (minimum) to get these designs into production and to the combat units.
While the aircooled engine does ditch the cooling system (300lbs per engine?) the R-1830 is about 100lbs heavier than the V-1710 so the weight savings is only 200lbs per engine not counting slightly larger cowling and such. Being down anywhere from 0 to 250hp per engine depending on which model of each each you are comparing isn't going to do much for performance when you count in the higher drag.
Known two stage R-1830 engines seem to be limited to 1200hp for take off and 1040hp/18,400ft or 1000hp /19,000ft depending on source. At any rate it seems it took 150-200hp to run the auxiliary supercharger so even a best case where you get a 1350hp take off R-1350 you are gong to down to 1150hp at just under 20,000ft. The 1350HP R-1830s were about 100lbs heavier than the 1200hp versions though. 1550-1575lbs? for single stage superchargers. Add 100lbs plus for the two stage supercharger.
I am not seeing any real advantage for the R-1830 here.

British fuel in P-38s. A throughly bad rap. The components of the fuel were known ahead of time and Allison was working an an improved intake manifold ( the gypsy queen) for ALL Allison engines, not just the turbo ones to solve mixture distribution problems. Eighth Air Force would have had a lot fewer problems if they had flown the P-38s as both Allison and Lockheed wanted them to. Low rpm and high boost would have helped keep intake manifold temperatures up in cruising conditions and prevented fuel puddling in the manifolds and poor mixture distribution. "Hanger talk" had the pilots flying at high rpm and low boost because they thought they could get to military power quicker if bounced. They also would have gotten more range on the same amount of fuel.
 
davebender said:
Not much point to using that large / heavy / expensive P-38 twin boom airframe unless you need the space for turbochargers. With mechanical superchargers you could employ a lighter and more compact airframe similiar to the Westland Whirlwind.
Click to expand...

Only if you use smaller, lighter and less powerful engines.
Don't get me wrong, I really like the Whirlwind but 1100lb/885hp (765hp for take off) engines are not 1450lb/1200hp engines, especially after you fit the bigger propellers and other assorted bits the bigger engine needs.


davebender said:
Speaking of which....
I wonder if the somewhat similiar Fw-187 airframe could have been powered by a pair of 950 hp BMW132 radial engines? Power to weight ratio would be pretty good even with such small engines.
Click to expand...

But the drag would have been horrendous. Frontal Area of the BMW 132 was 16 sq ft compared to the Jumo 210's 4.9 sq ft or the DB 601's 5.4. Granted cowling and radiators make up a bit of the difference but the 132 was actually several inches larger in diameter than the 801.

See Grumman Skyrocket with similar sized engines.
 

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  • f5f_grumman_skyrocket.jpg
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XF5F Skyrocket
Grumman XF5F Skyrocket - Wikipedia, the free encyclopedia
2 x R1820 radial engines.
3,677 kg Empty weight. similiar to Fw-187
4,600 kg Loaded weight. once again, similiar to Fw-187
383 mph max speed
4,000 ft / min. rate of climb.

If RLM had provided funding the Fw-187 would have been in mass production by 1940. An aircraft with the above performance plus exceptional endurance (1,100 liters of internal fuel) would have been a world beater during 1940 and would remain competitive through 1942. What's wrong with that?
 

Nothing is wrong with that if actually could have been achieved in service.
The F5F had 1200hp engines not 950hp engines, They are similar in size not power. The F5F was plagued with cooling problems which means that performance, if it was actually achieved and not an estimate might not be available in service. The plane was flown in both the short nosed, short nacelle,no spinner form without guns and in the long nose, long nacelle, spinner form with four .50s. I haven't seen yet which form the performance figures are for.
you also have to believe that this plane with it's 'streamlining' was over 40mph faster than a P-38 at sea level with the P-38 having another 125hp per engine.
 
Glad you do not have any objections vs. idea of P-38 with turboed Twin Wasps

Sorry, the source I've looked (book "P-38 in detail scale") states engine powers at just above 1100 HP for pre-P-38H

3. The single stage US Merlins were rated at 1300hp for take-off, 1240hp at 11,500ft in low gear and 1120hp at 18,500ft in high gear. Any 'over' boosting that might raise the power only raises the power BELOW those altitudes.
Click to expand...

Of course - some 10% extra power (WER?) at still decent heights.


Yep, that's why I don't trumpet very much about Merlined P-38 (contrary to P-51 Merlin): while superb plane on paper, numbers would've been modest compared with Allison engined one. Hence idea for Twin Wasp as alternative: very much feasible in 1941, all-American.


Again, I have nothing against P-38s performance, even more so for pre-J versions


Nope - we can take a WER of Merlin XX and then compare it with values of P-38J.



The advantage is availability lower cost, as I've stated in prior posting. If we loose 15 mph @ 20K vs. P-38s of 1942, so what. We can have 500 more planes in time allies were hard pressed, balancing out speed loss by a huge margin.


I've read that in a book I've stated above in the post - seems like authoritative
 
4,600kg XF5F loaded weight.
7,000kg P-38 loaded weight (early models).

The P-38 weighs about 50% more while having about 10% more engine power. It could probably beat the F5F in a sustained dive. Otherwise I suspect the F5F would have superior aerial performance.
 
tomo pauk said:
Sorry, the source I've looked (book "P-38 in detail scale") states engine powers at just above 1100 HP for pre-P-38H
Click to expand...

Seems to conflict with "America's Hundred Thousand", "The American Fighter" by Angelucci and Bowers and most importantly "Vee's For Victory" by Danial Whitney, the story of the Allison engine.


tomo pauk said:
Of course - some 10% extra power (WER?) at still decent heights.
Click to expand...

Define decent heights. It took the American's longer to get into the WER thing than the British. But even using British ratings from one book the XX engine gets to 1480hp, quite nice at first glance but that is at 6,000ft in low gear declining to the above mentioned 1240hp at 11,500ft after which the gear change can be made the power goes back up to 1480hp at 12,500ft but declines once again back to the standard 1120hp at 18,500ft. WER only works when the supercharger has 'extra' capacity. It NEVER works above the rated altitude or critical (full throttle hight) height of the engine.



It wasn't a superb plane on paper, and numbers would have been even more modest. Of those production numbers I gave 2/3 of the engines went to the British. As far as the win Wasp alternative goes, Something like 96 Two stage Wasps were delivered in 1941. Production per month didn't exceed 20 until June of 1942. Of the 324 F4Fs delivered in 1941 65 were F4F-3As with single stage engines, About 130 Were British Martlet IIs &IIIs, also with single stage engines and there may have been few left over Martlet I with Wright engines. Pratt Whitney was having trouble developing and Building the two stage engine despite the fact that they were cranking out 400-500 single stage engines a month.

tomo pauk said:
Nope - we can take a WER of Merlin XX and then compare it with values of P-38J.
Click to expand...

See above, 1480hp at 12,500ft doesn't quite equal 1425hp at 25,000ft.



tomo pauk said:
The advantage is availability lower cost, as I've stated in prior posting. If we loose 15 mph @ 20K vs. P-38s of 1942, so what. We can have 500 more planes in time allies were hard pressed, balancing out speed loss by a huge margin.
Click to expand...

I think the speed loss would be even greater and I don't think it was an engine shortage that held down P-38 production, There is more to aircraft production and tooling up factories than cost per airplane. The US already had a crapload of fighters that could do 360-370mph at 15,000ft, what it didn't have was a fighter that could do 370-400mph at 20-25,000ft. THAT is were the P-38 came in.


tomo pauk said:
I've read that in a book I've stated above in the post - seems like authoritative
Click to expand...

I could be wrong but I am going by a 11 page article in Volume 1, issue 2 of the 'Torque meter" by Daniel Whitney titled "The Allison Time Bomb" which seems to be a thorough examination of the problem. The 'Torque meter' is/was the journal of the AEHS whose website is here.

AEHS Home
 

Why would you suspect that?

We can look at the P-36/Curtiss 75 and the early P-40s and see a parallel.

Curtiss 75A-4 2608Kg loaded
Curtiss P-40C 3323kg loaded
27% more weight.

Curtiss 75A-4 1200hp at take off, 1000hp at 14,200ft
Curtiss P-40C 1040hp at take off, 1090hp at 13,200ft. 1040hp at 15,000ft ?
4% more power?

Curtiss 75A-4 323mph at 15,100ft.
Curtiss P-40C 345mph at 15,000ft.
6% more speed.

Curtiss 75A-4 2820ft/min initial climb.
Curtiss P-40C 2690ft/min initial climb.
4.6% less climb but then the engine in the 75A-4 was rated at 1200hp for 15% more power.

Not seeing a big improvement here just because of lighter weight.
I wonder the extra drag of the radial has something to do with it.
 

What power was practically extracted from V-1710s in F G models of P-38, according to those books?



Indeed, they do not equal, so I'd reduce my estimates of Merlinized P-38 to achieve performances somewhere between H and J models, achieveble in late 1942



The mech-supercharged Twin Wasp would've been less complicated to build then turboed one, or turboed Allison version, thereby speeding up preparations for alternative production line. And even if I agree that such a plane would do only 370mph @ 15K, that's still plenty of performance for Japanese fighers to deal with until Hayate or Raiden show in - in 1944. Now before people cut in to say that P-39 and/or P-40 were able to fly as fast, we calculate in range, sturdiness and multi-role capability such P-38 would've possessed, and then draw conclusions. We can take a look at other Allied (and Axis) planes, and have trouble to find a plane that would be better in range-speed-firepower-durability combo such a P-38 would've offer. Spitfire Mk.VIII as only contender, from late 1942 - really shame it wasn't produced in more examples.



Hmm, so choosing alternative engine configurations would've made such pilot-induced engines less likely to happen. I stand corrected re. Brittish fuel issue
 
tomo pauk said:
What power was practically extracted from V-1710s in F G models of P-38, according to those books?
Click to expand...
There is a bit of conflict so, in the interest of learning with you, I found 'specific engine flight charts' from the flying manuals for the planes in the manual section of this website. This what the Army said the pilots could do.

P-38D-E
1150hp take-off rating could be used at from sea level to 25,000ft. It was also the military power. 5 min time limit.
1000hp max continuous to 28,000ft. No time limit, could be used until the fuel ran out temperatures permitting but you got short range.
NO WER

P-38F
1240HP take-off to 21,000ft 5min limit.
1325hp military to 15,000ft 5 min limit.
1000hp max continuous to 28,000ft.
NO WER

P-38G
1240hp take off to 21,000ft 5min limit.
1425hp military to 15,000ft 5 min limit
1100hp max continuous to 24,000ft.
NO WER

When taking off with heavy loads on short runways the pilots were allowed to use the military rating as a WER take off rating.

The P-38H showed a major improvement.
1425hp take off to 22,000ft 15min limit.
1600HP WER to 10,000ft 5min limit.
1425hp Military rating to 24,900ft 15 min limit.
1100hp max continuous to 34,000ft no limit.

fitting the 'chin' intercoolers to the same engines on the "J"s changed things to:
1425hp take off to 26,600ft 15 min limit.
1600hp WER to 28,700ft 5 min limit.
1425 Military power to 29,000ft 15min limit
1100hp Max continous to 22,800ft no limit.

tomo pauk said:
Indeed, they do not equal, so I'd reduce my estimates of Merlinized P-38 to achieve performances somewhere between H and J models, achieveble in late 1942
Click to expand...
See above, not counting the weight reduction, a Merlin XX powered plane may beat the P-38F at certain altitudes but somewhere above 15,000ft it looses whatever advantage it had. As for equaling a P-38G, that doesn't look likely and any version after the "G" it is no contest.




All you have simplified is the booms, or you have changed problems and gotten rid of the radiators, the two stage Wasps still need intercoolers of some sort. installing heavier engines forward of the CG while pulling radiators from behind the CG is going to take a bit of working on. It is doable but this is not fast or easy with engineers and draftsmen in short supply. And you still need all the tooling, jigs, fixtures and work force for the second production line.
Allison got about 10% better fuel economy than the Merlin, not sure how the wasp compares but higher drag at cruising speeds isn't going to help either. Yes you may be able to cram enough fuel into the plane to get the range you want.
Two stage Wasps at the time you want them (lets assume you can get them) have:
1200hp for take off at 2700rpm
1200hp military at 1800ft at 2700ft
1040hp military at 18400ft at 2550 rpm
1100hp max continous at 3300ft at 2550rpm
1040hp max continous at 13,000ft at 2550rpm
NO WER.
2 stage Wasp weighed about 200lbs more than an Allison so weight savings from losing the radiators and turbos, while there, is not so much as at first glance.
You can trade fuel for turbo weight but you have less power to lift weight from runway once you get to the 'G" model.

Add you still don't have a plane that could fly "top cover" to prevent enemy planes from diving on your formations from above.



tomo pauk said:
Hmm, so choosing alternative engine configurations would've made such pilot-induced engines less likely to happen. I stand corrected re. Brittish fuel issue
Click to expand...

That or just better training to begin with
 
I sure can learn from people that have your way of sharing stuff. Thanks

The main reason I've gotten in thinkering about re-engined P-38 was premise that such a version would've increased availability of the plane, not that it's original performances were lacking - as stated in 1st post re. such P-38.
 
main reason I've gotten in thinkering about re-engined P-38 was premise that such a version would've increased availability of the plane
Click to expand...
If engines are in short supply then the USA should build a new engine plant, which takes about 2 years to become fully operational. The USA had the money and the time.
 
Having hundreds of new planes (with good performance) in 1942 means as much as thousands of new planes in 1944, for Allied cause - hence my turboed mech-supercharged proposals for Twin Wasp in P-38. Very much feasible in 1941/42.
 
tomo pauk said:
Having hundreds of new planes (with good performance) in 1942 means as much as thousands of new planes in 1944, for Allied cause - hence my turboed mech-supercharged proposals for Twin Wasp in P-38. Very much feasible in 1941/42.
Click to expand...

If turbos (actually the turbo controls) are giving problems on the V-1710 engine why do you think the very same turbo from the same company (GE) using the very same turbo control units is going to be trouble free on the R-1830?
The Turbos and turbo controls were NOT quite ready in 1941/42 on any engine.
 
davebender said:
If engines are in short supply then the USA should build a new engine plant, which takes about 2 years to become fully operational. The USA had the money and the time.
Click to expand...

What Money and what time?

in 1938 you had TWO US plants that made large aircraft engines. They were joined by Allison in 1939, if you can call 46 engines large production. Allison went on to build 1178 engines in 1940.

Allison's proposed Plant 3 was 390,000sq ft at it's ground breaking in 1939. It was over 3 million square feet by June of 1943. And a number of General Motors plants were doing major subcontracting.

P&W quadrupled the size of their factory between 1938 and 1940.
Wright also had massive expansions of floor space.
The Government gave Ford over 14 million dollars in 1940 to build a new factory to make R-2800s, Packard go the deal to make Merlins in 1940.
neither produced any engines to really speak of until 1942.
Wright by the middle of 1941 had completed their Cincinnati Plat, the largest aircraft engine plant in the west.
In the spring of 1942 Studebaker, Buick and Chevrolet all started delivering engines from either new factories or from extensively retooled ones. Work on them had started months if before if not in late 1940/early 1941.
Nash Joined in by the end of 1942.
All these factories were either under construction or being planed before Pearl Harbor.
This does not take into account the enormous amount of sub-contracting that went on. For instance that Huge Cincinnati plant was being fed by, the Ohio Crankshaft company (crankshafts), Otis elevator (crankcases), Hudson Motor Car Company ( Pistons and rocker arms), Eaton manufacturing company (propeller shafts) and the Graham-Paige Motors Corporation (Master and articulated connecting rods).

Many of these aircraft engine factories doubled or tripled their sizes by the time they hit peak production in 1944. For example that Ford factory for the R2800 went from 890,000sq ft planned sq ft for 300 engines per month in the fall of 1940 to a 536,000sq ft addition completed Feb 1 1942 to June 1942 plan of 2,618,000sq ft and planned out put of 1800 engines a month to a Jan 1943 plan of a total of 3,852,000sq ft and a planned 3400 engines a month, this was later scaled back to 3100 engines per month but the factory set a peak production record of 186 engines in one day in July of 1944.

If you want more engines at the start of 1942 you had better go back to the summer of 1939 to make any real changes.

Every war related industry was competing for factory space, machine tools, trained workers (or training them themselves) and even raw materials.
Allison at one point in 1940 when strategic materials were getting hard to come by found a stock of 2,000tons of steel bars of an unusual shape that were considered unusable. Allison bought the bars sent to steel mills to re-rolled and heat treated. This was done before the government froze vital materials and instituted a priority system. This stock of material lasted them into 1942 by which time the Government priority system was working well.

America was still coming out of the depression. Even if the money spigot opened up there was only so much you could buy because the mines and factories that made the raw materials and machine tools needed time to gear up to the new demands.
 
davebender said:
I agree. Otherwise the P-40E would be an excellent candidate for a turbocharger.
Click to expand...

were would you put it?

you need somewhere between 10 to 15 cu ft of space for the turbo, the intercooler and ducting. Throw in a few CG problems and the fact that the ducts need to be certain sizes and can't be squashed down to fit some existing space and you might wind up with a rather different aircraft.

Like the XP-60A;

 

I've thought it was Allison/turbo combo that needed to be treated in a certain way, while turboed 1830 was void of such an issue?
Were the P-43 experiencing any issues with their powerplants?
 
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