Fighters Made in USA, for mid 1943: how would you do it?

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The concept drawing for P-40 high-altitude, developed perhaps after the -C version. Complete installation is in chin, coolers relocated in wings. That, along with loss of hull MGs would've, at least partially, cancel out the shift of CoG after turbo is mounted.
 

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a few problems.
1. The turbo appears to be upside down.


the large pipe exiting to the right is the waste gate. Adding pipe to it to get it out side the airplane isn't that big a deal. All those blades/buckets is where the exhaust comes out when the turbo is actually working. You appear to have it pointed up at the crankcase of the engine. Not good for both cooling the exhaust turbine and cooling the engine itself. There is a reason most US turbo installations had that part of the turbo exposed to the outside air.

2. you are back to the short exhaust pipes to the turbo. Allison found in the turbo compound experiments, with the turbo behind the engine that exhaust gas temperature could exceed 1750 degrees F in the inlet to the turbo.

3. The cowl .50 cal guns actually stuck through the upper corners of the instrument panel just a tiny bit. They were actually pretty much on the CG to begin with. Weight savings yes, CG shift no.
 
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There really isn't much to do beyond putting the P40 up. If the P51/F4U are out of the picture, the P47 is already up and P38 is moving along, only the Packard engined P40 is left. Maybe the P63 but that was a fighter from a time gone by (local defense) and all the action was in the attack end of the world.

If the P40 can make the trip from England into France, it might work. But it is an older design. Curtiss's P40 replacement might be a better call.
 
As already said, a concept drawing

Now to the points:
1) the turbos for B-17 -24 were upside down, when compared with P-38 and worked fine (I know not same types/engines). Or we can move turbo slightly down, and top-down, so the duct inlets are above. That way we can make place for exhaust manifolds to be longer, applying a kind of more elaborate S shape for manifolds in same time. That also solves the issue #2.
3) Oil glycol coolers, radio, hydraulic tank pump, oxygen bottle - all can get relocated further aft. Plus the tail can get longer, as in later P-40s. The hull tank can grow slightly.
 

I don't look at such a P-40 as some world beater, more a kind of back-up if some of new fighters have trouble to perform as advertised.
Think all this sqetches are getting better of me

I've taken a look only at 39, 40 and 47 so far
 
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P-47 with some legs.
Two new fuel tanks for some 150-200 gals (520-570 internal total for 1943). Ideally, we can move the pilot back and put a bigger main tank in front, since all of this fuel would've disturbed CoG. All while praying that water injection is ready for summer of 1943
 

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tomo pauk said:
I don't look at such a P-40 as some world beater, more a kind of back-up if some of new fighters have trouble to perform as advertised.
Think all this sqetches are getting better of me

I've taken a look only at 39, 40 and 47 so far
Click to expand...

I agree with you. P40 has the main advantage of being available. But in the form of the late 30s/early 40s airframe, the old P36 version, it really wasn't a second gen aircraft. Needs a bit of reworking. But, as they say, the perfect is the enemy of the good enough. In the early war period, it was good enough. By 43, there were other birds out there that were better.
 

The Turbo actually doesn't care if it is turbine up, turbine down, turbine left or right or turned so turbine/compressor shaft is parallel the engine crankshaft. What is important, both for the turbo turbine and for the rest of the engine, is getting rid of the exhaust gas in way that doesn't add heat to the engine compartment or any thing else you are trying to keep cool. And also provides a flow of cooling air over the turbine blades/buckets to keep them cool. The simplest way was to mount the turbo in such fashion as to have the exhaust from the turbine dump directly to the outside air. Here is a B-17 turbo.



You can see the wastegate open in the pipe. you can also see the amount of sheet metal 'cut away' in both this picture and the P-38 picture to provide cooling for the turbine section despite the drag penalty. You can hide the turbo inside the fuselage for better streamlining but you have to duct the exhaust out (both wastegate and turbine) and duct cooling air for the turbine into and out of the turbo "compartment".
I was in error on the earlier post, while Allison did go to 1725 degrees on the turbo compound experiments (not 1750) normal turbo operation for GE turbos was to keep turbine inlet temperatures to 1600 degrees max.
You need adaquate sized exhausts to handle the flow and while an "S" bend snaky pipe may help the exhaust cooling it adds bulk and drag if outside the cowl, it doesn't cool as well if inside the cowl and the more restriction you put in the exhaust "system" the higher the back pressure at the exhaust ports which lowers power and hinders cooling of the exhaust valves which shortens their life. Allisons might be better at this last than some other engines.

here is a Picture of the Curtiss XP-60A using an Allison V-1710-75 engine with planned turbo charger.

http://upload.wikimedia.org/wikipedia/commons/7/71/Curtiss_XP-60A_061024-F-1234P-016.jpg

This what the Curtiss engineers thought it would take to put a 1425hp turbo charged Allison into a single engined airframe BEFORE Pearl Harbor.
 
Don't see the pic of B-17 turbo

The data about tha XP-60A is rare as hen's teeth. Care to add some?
Judging at the pictures, XP-60A featured turbocharger behind/under pilot, unlike my proposal.

Here is another take on the turbo installation. Red 'tubes' depicts exhaust manifold, ducted to turbine (only one side deoicted), then exhaust over board, green 'tubes' show air inlet to compressor, then to inter-cooler and finally to carb, blue are cooling ducts (to i.-cooler and out). Note that exhaust tubing is curved at angles above 135deg:
 

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I wonder how much the intercooler placed where you have could cool the intake charge ?
The intercooler is in between the exhaust pipe from each side of the engine, only a little back from the turbo itself, plus the cooling air for the intercooler passes right over the turbo unit, which would heat the cooling air even before it gets to the intercooler. Very compact, but probably not very efficent.

In addition placing the turbo directly below the engine, just separated by the intercooler cooling duct, which would carry some of that heat away ( into the intercooler), just doesn't seem too safe. Anything that leaks from the engine will end up in the bottom of the cowling, touch that very hot turbo, and instantly ignite.
 
Then we'll put a aluminum sheet under the engine, or maybe between turbo and i.-cooler intakes

The cooler part of the turbo is near i.-cooler intakes anyway, so that shouldn't be that much an issue. P-38 had issues re. i.coolers, but it was able to pull 1325 1425 from deck to high alt, in 1942 and 1943 respectively.
 
My take on P-51:
All Packard Merlins allocated for the USAAC go there, once we have airframes (some time late 1942). As a back-up, if in 1943 airframe production surpasses that of engines, V-1710 geared for 15kft+ critical altitude. Adapt the airframe to carry 6 HMGs.
No A-36s; P-40 gets dive brakes if we lack funds for fighters. Start adjusting the airframe to two-stage Merlin, with Packard establishing new production lines for that engine, so we could field it in spring of 1943. Add hull fuel tank of size that doesn't hamper handling and performance too much. Perhaps having 21 (single stage PM : two stage PM : Allison) ratio between P-51 types at hand in mid 1943.
 
tomo pauk said:
Don't see the pic of B-17 turbo
Click to expand...

My appoligies, I am not very good at getting pictures to appear in the posts, sometimes they do and sometimes they don't.
tomo pauk said:
The data about tha XP-60A is rare as hen's teeth. Care to add some?
Click to expand...

Data is a bit scarce and sometimes confusing. Most performance data is based on Curtiss "estimates" of performance because of the limited flight testing done.
It also has some aspects that don't make sense to me. Like a service ceiling of 35,200ft for a turbocharged airplane?
Estimated speed was 420mph at 25,000ft and 324mph at sea level. Test flights were undertaken without the turbo after a small fire in ground running/taxi tests. Low altitude speed and climb (where the turbo doesn't add anything anyway) were described as disappointing. The Merlin powered XP-60 which used the same wing but a fuselage much closer to the P-40 was found to have it's wing not manufactured to the tolerances needed to gain any benefit from the laminar flow. Similar problem for the XP-60A? could it be fixed?
Empty weight is given at 7,806lbs and normal gross as 9,616lbs which doesn't leave a lot of useful load. While there was tankage for 200 US gallons it seems this gross weight only included 116 US gals and ammo was only 200rpg. Climb seems in the 2500ft/min range.

tomo pauk said:
Judging at the pictures, XP-60A featured turbocharger behind/under pilot, unlike my proposal.
Click to expand...
I believe it was. However the Curtiss company/engineers had built planes with the turbo under the engine, they were called YP-37s.

http://www.aviastar.org/pictures/usa/curtiss_p-37.gif

Please note that these planes used the old "C" series engines with the longer gear case that positioned the prop 6 in lower than the -39 engine in the P-40E. Also that the turbo is located under the rear half of the engine, intercooler and radiators are located inside the fuselage over the wing leading edge. Area were the cockpit normally is has oil tanks, coolant header tanks and extra fuel tank normally behind pilot on P-36/40. Considering that this plane was built before the P-40 the Curtiss engineers may have had an idea of what they wanted to go were and why. Taking out the inboard guns in the wing and using the space for the radiators may help but anyway you look at it stuffing a turbo into a P-40 airframe is going to be a tight fit. difficult to maintain fighters (hanger queens) may not be what the USSAF needs in 1943
 
I think it would take more than a little aluminum sheet to isolate the heat from the turbo.

I've seen the exhaust portion of modern turbos get red hot under dyno pulls. WW2 era turbos probably operated at lower temps, but most installations i've seen locate them away from parts of the system that needs to be cool. You've surrounded that intercooler with every heat producing part a engine has.
 
Designing a plane around the turbo is always better than attacking a turbo installation at an existing plane type; F4U being an exception perhaps, since it appears it's turboed one-off was a good bird.
OTOH, having 500 of planes that do 1400 HP is better than having 100 ones with 1600, if one is fighting the war.
 
Thanks for the info, SR6

Sticking a turbo into a SE plane, while not adding the bulk, produces either the low performance type, or the one with low fuel/ammo/armament contents, or a 'hangar queen'*, or a combination of those. At least that's what I've read about historical types. I've tried to use the bulky chin of P-40 to 'produce' not a world beater, but a good performer @ hi alt and hopefully easier to maintain than P-38.
If we add the bulk, we can go Republic's way
 

Max exhaust gas inlet temperature for the WW II Turbos was 1600 degrees F, they glowed quite nicely at night
 

While a single engine plane will require less maintenance than a twin, if the twin has the parts spread out and decent access it may not be that much worse than a single with restricted access. I once had a car in which the simplest way to get the oil filter out was to disconnect a fuel line. When it was changed from right hand drive to left hand they ran the steering column through the area next to the oil filter
 
For the sake of using aircraft in a strictly fighter roll I would delegate P-40/39s to the front line and point defense positions and use P-51s and P-39s as interceptor and long range attack runs as well as escort fighters. I know the P-47 was still under developed and saw limited service by 1942, however it was still the only "fighter" plane that could fly higher than enemy aircraft and be a competitive performer in that roll and for that reason i would still delegate a significant portion of P-47s for top cover over combat areas. It wouldn't be til the Merlin 1650-9s were introduced where the P-51s could replace the P-47 in that roll.


bill
 
That would've been roughly my idea, too (the P-38 instead of P-39 as interceptor/LR fighter - typo?).
The USAAC F4U would've been neat, I agree with opinions of many fellow members. The machine proved itself in Marine hands, so Army would've been just fine with it. Esp. with a dedicated land plane version, saving perhaps 300-500 lbs by deleting arrester gear and having non-foldable wings. The lower hull would've been also built lighter hopefully, since it wouldn't have to endure rough landings. Of course, birdcage needs replacement ASAP. The plane have had generous wings, so perhaps some wing cropping would've been good, now the plane is lighter, to extract some speed.
The main issue is where to produce it. With so many fighter types in production, perhaps having Vultee to build it would've been good? The plane can double as a dive bomber, too.
 
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