Improve That Design: How Aircraft Could Have Been Made Better

[wuzak]

So it would just go around the pathway of the turbine outlet? Forcing air forward like that sounds like an awesome way to produce drag.

The turbine outlet is facing down form the aircraft. The intercooler pipes are inside the aircraft.

 

[Zipper730]

The turbine outlet is facing down form the aircraft.

That I'm aware of, but I'm looking at the diameter of the exhaust outlet where the airflow goes through the turbine and out...

... as I understand it, it's that ring shaped hole with the blades: I'm thinking that, thing's gotta be something like 1.5-3.0 feet in diameter.

Looking at the airflow path on the XP/YP-37: The carburetor intake goes slightly upwards; then rearwards to pass through the compressor. From that point, it goes through the intercooler, and from there, upwards, and then forwards to the fuel injection manifold and main-stage supercharger, and into the engine? I just want to make sure I'm perceiving everything right

 

[BiffF15]

That I'm aware of, but I'm looking at the diameter of the exhaust outlet where the airflow goes through the turbine and out...

View attachment 544586
... as I understand it, it's that ring shaped hole with the blades: I'm thinking that, thing's gotta be something like 1.5-3.0 feet in diameter.

Looking at the airflow path on the XP/YP-37: The carburetor intake goes slightly upwards; then rearwards to pass through the compressor. From that point, it goes through the intercooler, and from there, upwards, and then forwards to the fuel injection manifold and main-stage supercharger, and into the engine? I just want to make sure I'm perceiving everything right

Zipper,

Nice shot!

Greg,

Any idea how many Lightning's are flying with operational turbos?

Cheers,
Biff

 

[wuzak]

Looking at the airflow path on the XP/YP-37: The carburetor intake goes slightly upwards; then rearwards to pass through the compressor. From that point, it goes through the intercooler, and from there, upwards, and then forwards to the fuel injection manifold and main-stage supercharger, and into the engine? I just want to make sure I'm perceiving everything right

I guess it has to, since enter under the nose and go into the compressor inlet.

In the case of the YP-37 the inlet is on top of the installed turbo. The XP-37 used a different turbo design, at least initially, where the air entered the compressor in the space between the compressor and turbine housings.

The P-40F had the radiator mounted under the nose and an updraft carburetor, so the arrangement I propose is possible.

 

[wuzak]

As I understand it, an intercooler includes air drawn in from the outside, and cycled through tubes/grills/passageways (a radiator) which absorb the heat from the air passing through the carburetor intake on the way to the engine. The heat from the carburetor is transferred to the airflow in the intercooler, which then is routed overboard.

The intercooler on a V-1710 plus turbo is before the carburetor. I think you mean compressor.

Makes sense, but I'm figuring the turbo has hot exhaust gas flowing out of it. If the duct was like the P-38J, wouldn't the air get cooled off, then heated up by a whole bunch of hot exhaust gas blowing in

The air that is cooled is inside the ducting that is routed back to the engine.

The exhaust does not enter the ducting. The only way the exhaust affects the cooled air is if the manifolds or exhaust gas passes close by the duct, transferring heat.

The exhaust gas from the turbo in my hypothetical P-37 would enter the air that has been warmed by the intercooler.

 

[pinsog]

That I'm aware of, but I'm looking at the diameter of the exhaust outlet where the airflow goes through the turbine and out...

View attachment 544586
... as I understand it, it's that ring shaped hole with the blades: I'm thinking that, thing's gotta be something like 1.5-3.0 feet in diameter.

Here are the sizes for early turbochargers on P38. Not sure what model P38 your pic is

 

[Zipper730]

You may note that I said the intercooler would be mounted ahead of the turbo.

That's one idea, but I was also thinking about the fact that, with the radiator repositioned to the wings; the volume of the intercooler could be reduced and shaped in a way to be more compact. Furthermore, the size of the nose would probably allow an oil-cooler to be there even if the radiator wouldn't fit in the nose.

As for the intake path for the intercooler, would there be enough room in the wings to pull that off, or would you cut into the wing-fuel space?

Well, that aside, I'd also thought about removing and repositioning equipment, much as was done in the P-40.

1. Auxiliary Fuel Tank: Repositioned behind/below pilot
2. Radio-Transmitter & Receiver: Repositioned aft of cockpit
3. Battery: Repositioned aft of cockpit
4. Hydraulic Tank & Pump: Repositioned aft of cockpit

Just with those mods alone, about this much length could be trimmed off the nose.

 

[Shortround6]

The stuff may fit behind the cockpit (although you are working on a 2 dimensional plan) see;

fuselage is lot narrower behind the cockpit,
Tail has to say a certain distance behind the wing or control of the aircraft goes out the window (plane becomes unstable)
Just because something "fits" doesn't mean the weight and balance are going to be correct, stuffing a lot of heavy stuff in the rear of the plane leads to sme real CG problems,

The YP-37 may look long, but it was actually 9 inches shorter than P-40, P-40B & C

 

[tyrodtom]

The XP-37 has basically nothing behind the cockpit except that baggage compartment, ( which if you look at the specs, is probably limited to 20-30 lbs)

Moving equipment back there whose combined weight is probably at least a couple hundred pounds just wouldn't work out CG wise.

 

[Zipper730]

The stuff may fit behind the cockpit (although you are working on a 2 dimensional plan)

I really do appreciate the three-view image. It reveals some stuff of great use

1. I didn't realize the design had such large fillets: The P-36 didn't seem to have them, and neither did the P-40 for that matter, actually.
2. The carburetor intake is interesting to say the least. I didn't know the intake was only on one side.

It does raise some questions about where some things could be repositioned: For starters, I'm curious if the radiator space also includes the oil-cooler (the radiator, intercoolers are all next to each other). Also how big is the oil-cooler relative to the carburetor intake?

fuselage is lot narrower behind the cockpit . . . . The YP-37 may look long, but it was actually 9 inches shorter than P-40, P-40B & C

The P-40 is actually fairly narrow in the back. This design is a bit plumper up-front, which I'm not sure is due to the turbocharger (most likely due to the displacement of various other items), the radiator configuration, or the fact that the exhaust pipes have to be tapped to feed the turbocharger.

I'm not entirely sure how the C/G compares to the P-40, as it's a little bit shorter, but the wings do look a bit further back on the airframe. I'm surprised that the design would have less weight up front than the P-40 (the turbocharger and everything): The only thing that would likely result in more weight in the middle/aft would be the radiator position (on the P-40 it's below the nose), though the XP-40 actually had a belly radiator proposed (it didn't seem to work).

How much mass is in the cockpit?

 

[pinsog]

If you want to turbocharge the P40 I think your going about it the wrong way by using the YP37 as a starting point. If you want to turbo charge the P40, I think the best way would be to start with a standard P40, put the turbocharger behind the cockpit partially exposed like a P43. Make just enough space down the middle of the plane between the wing tanks for a 6 inch diameter pipe half exposed in the belly going to the turbocharger and the return pipe on top of that one. I have no idea where the intercooler would go, I guess in the back near the turbocharger with flaps to control the amount of air.

Personally I think the P36/Hawk 75 would be MUCH easier to turbocharge. Intercooler directly behind engine with turbocharger just like P43, in the belly behind cockpit, exposed, pipe to turbocharger half exposed, return pipe on top. Turbocharged P36/Hawk 75 would be much slower than P40, especially at low altitude, but would climb like crazy compared to any contemporary fighters with no drop in performance at high altitude. I believe this plane could have dominated early war up through 1941 in Europe and done well in the pacific through 1944. Using the cube rule, a P36/Hawk 75 with a turbo charger should do around 360 at 25,000 feet.

While we are at it, put it in a wind tunnel and clean up that wing and landing gear, you don't see those bulges and crap on a Zero, one of the keys to a Zero's performance on such low power.

 

[MX-2054]

Now, does that mean guns that didn't exist (but could be made with existing technology?)
Engines that wouldn't exist for a year or more?

and so on.

At that point it just becomes the "ideaI piston-engine WWII fighter design*," which I have a very detailed idea of by now, but I'm sure everyone has their own idea of one too. For that I just used the GSh-30-1. It makes the armament design much easier but certainly isn't a WWII design even if it can be made with WWII technology.

*More accurately described as the fighter (including engine, weapons, etc.) you would create if you had to design/specify one from scratch in the 1930's.

 

[Shortround6]

For that I just used the GSh-30-1. It makes the armament design much easier but certainly isn't a WWII design even if it can be made with WWII technology.

Can it be made with WW II technology (or pre-war technology)?

There may be nothing about the design that is really startling. But the devil is always in the details. There were a lot of improvements in metal alloys and heat treatment between WW II and the 1980s that allowed for higher performing guns at low weights. Assisted by better testing techniques and quality control.
The lowering of the life span of the guns (making them semi disposable) didn't hurt the weight either

The GSh-30-1 needs a pretty good engine too. While the gun is light the ammo is not. 100 rounds weighs almost twice what the gun does and that 100 rounds weighs as much as 600 round of .50 cal ammo or 3000 rounds of .303/7.7mm.
The 30mm is much more destructive but you either need to fire one gun through the prop hub (which may be all you need?) or you need a large engine in order to haul one gun in each wing with ammo.

 

[P-39 Expert]

Definitely all you would need.

 

[Zipper730]

If you want to turbocharge the P40 I think your going about it the wrong way by using the YP37 as a starting point. If you want to turbo charge the P40, I think the best way would be to start with a standard P40

I agree with this idea.

Does anybody have a drawing of the P-40J proposal, which was to involve a turbocharger. Nothing was ever built, but I'm curious if any drawings exist.

 

[Kevin J]

I agree with this idea.

Does anybody have a drawing of the P-40J proposal, which was to involve a turbocharger. Nothing was ever built, but I'm curious if any drawings exist.

It's called a P-60. P-40 fuselage with larger laminar flow wing.

 

[Zipper730]

It's called a P-60. P-40 fuselage with larger laminar flow wing.

I thought that came later?

Regardless, where did they put the turbo?

 

[MX-2054]

Can it be made with WW II technology (or pre-war technology)?

There may be nothing about the design that is really startling. But the devil is always in the details. There were a lot of improvements in metal alloys and heat treatment between WW II and the 1980s that allowed for higher performing guns at low weights. Assisted by better testing techniques and quality control.
The lowering of the life span of the guns (making them semi disposable) didn't hurt the weight either

It should be able to be built with WWII or earlier technology, with some increased weight and reduced barrel life. Metallurgy has relatively little to do with improved gun performance, it mostly increases barrel life and allows the gun to be made slightly lighter by making its component parts lighter. The smaller size and improved performance of guns (rate of fire for a given cartridge) is mostly due to mechanical improvements. The mechanical design of the GSh-30-1 in particular is very efficient, with its lever-based system allowing it to mostly keep its rate of fire even when redesigned with a heavier barrel.

I'd guess a WWII GSh-30-1 would be about 60-65 kg, and have a barrel that would essentially have to be replaced after firing a single load of ammunition, but would still have the same rate of fire and size. It would be mounted in the propeller hub (it can't be synchronized and if it was wing-mounted outside the propeller arc its recoil alone would necessitate a very heavy and strong wing).

The GSh-30-1 needs a pretty good engine too. While the gun is light the ammo is not. 100 rounds weighs almost twice what the gun does and that 100 rounds weighs as much as 600 round of .50 cal ammo or 3000 rounds of .303/7.7mm.
The 30mm is much more destructive but you either need to fire one gun through the prop hub (which may be all you need?) or you need a large engine in order to haul one gun in each wing with ammo.

For that I required an electronic rate reducer (used on the A-12.7) to allow the gun to be fired at full or half its rate of fire. 10 seconds of cannon fire (the lowest commonly found time in WWII fighters) would require 250 rounds at 1500 rpm, and 125 at 750 rpm. The 250 rounds would be too heavy, so I settled for 150 rounds (coincidentally the same as the ammunition load of the gun in real life), and assumed the gun would have to be fired at reduced rate to get 10 seconds of fire out of it, with the full rate used in situations requiring more firepower.

 

[wuzak]

I thought that came later?

Regardless, where did they put the turbo?

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

File:XP-60 - Ray Wagner Collection Image (27409064984).jpg - Wikimedia Commons

The XP-60 program started as the XP-53 program with the IV-1430. The XP-60 flew a couple of months after the first P-40/Merlin did.

 

[Shortround6]

The smaller size and improved performance of guns (rate of fire for a given cartridge) is mostly due to mechanical improvements.

And better springs.