Pinnacle of Piston fighter: XP-72 vs Spiteful Mk XVI? (1 Viewer)

[Jugman]

Time machine.

From page 443 of "Vees for Victory"
"V-1710-41 2550+ bhp, turbo-compound w/separate 2-stage S/C and 2-stage air-cooled turbine, 50% aftercooler and port injection, 1947.

Also on Page 280, short description. Based on the G-10 which was a modified E-30 derived from the E-27.
E-27 engine
View attachment 796412
Just take of the engine driven supercharger, replace the single stage aux supercharger with a 2 stage supercharger, replace the single stage exhaust turbine with a two stage exhaust turbine. Install an after cooler, install port fuel injection, already has water injection.

Easy-peasy to put in a Spitfire in 1940

You Know a clam shell type bubble canopy like the F-16 has was technically feasible for a 1936 fighter. Are going to make some silly comment about needing fly-by-wire and advanced composites and CAD to make it happen? Obviously a 1936 clam shell bubble canopy wouldn't be the exact same design or materials. The same goes for a "turbo Spitfire"
And I do believe two-stage impellers and turbines predate 1940. I want to say the French for both of those but I can't remember.

 

[Reluctant Poster]

You Know a clam shell type bubble canopy like the F-16 has was technically feasible for a 1936 fighter. Are going to make some silly comment about needing fly-by-wire and advanced composites and CAD to make it happen? Obviously a 1936 clam shell bubble canopy wouldn't be the exact same design or materials. The same goes for a "turbo Spitfire"
And I do believe two-stage impellers and turbines predate 1940. I want to say the French for both of those but I can't remember.

Who knew how to make a large blown canopy in 1936? Perspex and Plexiglass were brand new materials in 1936. As far as I can tell the first use was in the Spitfire. Everyone else was building birdcage canopies until production techniques had evolved enough to produce large blown Plexiglas in mass quantities

You have to learn to crawl before you learn to walk. The conceit that you can jump straight to the final result without the hard work of development is nonsense.

As for turbo chargers materials were the main issue. GE didn't get their turbine materials sorted until 1941. From

"Cooperative research by Haynes Stellite and General Electric into the possibility of using Hastelloy alloy A, B, or C as a material for turbosupercharger buckets was begun in 1937. Forging was extremely difficult because of the great hardness and strength of these alloys at high temperature, but GE eventually developed a successful technique, the first one to succeed in drop-forging a Hastelloy alloy into any finished shape. Tests were also made of buckets which were cast to size by Austenal, but they were not liked so well as the
forged buckets, both because it was extremely difficult to produce sound, accurate castings and because the casting process gave a much larger grain than forging, while experience to date was believed to indicate that fine grain was essential for turbine buckets. The result was that by the middle of 1941 GE had decided that the best available method of producing turbo buckets was to forge them of Hastelloy alloy B. Eventually research done by GE on cast and forged Hastelloy buckets led to the discovery that at the 1,500°F-1 ,600°F blade temperature of the turbo the large grain of castings actually gave superior strength after 200 or 300 hours of life, but it would seem that this had not yet been fully realized by the middle of 1941.
By this time, however, it was clear that because of the war, buckets for turbosuperchargers would have to be made in enormous quantities, and that there was not nearly enough forging capacity in the United States for the use of that method of production, particularly since Hastelloy alloy B was so hard at the forging temperatures that the dies wore out very quickly. The result was that Austenal set to work in cooperation with GE to develop its lost-wax casting process to be really satisfactory for casting turbo buckets, and to make it suitable to true mass production. Austenal found it much easier to produce good castings of the Haynes Stellite alloy closely related to Stellite No. 6 which Austenal sold in dentures under the name Vitallium than of any of the other alloys tried. It was only then that tests were made by GE which revealed that Vitallium had really superior properties as a bucket material. The casting process had been developed to the point where it was satisfactory for buckets by the end of 1941, and Austenal then developed from the denture alloy a slightly modified composition which contained less carbon and hence was less brittle and better suited for turbine buckets. As soon as this casting process and alloy were approved for production by the Army, the Haynes Stellite Company was called on to assist in working out methods for mass production. The modified denture alloy was further improved by Haynes Stellite; the resulting material was designated Stellite alloy No. 21. This proved an excellent material for the purpose and actually far better than Hastelloy alloy B would have been, since the latter material contained no chromium and had very poor resistance to oxidation above about 1,400°F. "

 

[Reluctant Poster]

Time machine.

From page 443 of "Vees for Victory"
"V-1710-41 2550+ bhp, turbo-compound w/separate 2-stage S/C and 2-stage air-cooled turbine, 50% aftercooler and port injection, 1947.

Also on Page 280, short description. Based on the G-10 which was a modified E-30 derived from the E-27.
E-27 engine
View attachment 796412
Just take of the engine driven supercharger, replace the single stage aux supercharger with a 2 stage supercharger, replace the single stage exhaust turbine with a two stage exhaust turbine. Install an after cooler, install port fuel injection, already has water injection.

Easy-peasy to put in a Spitfire in 1940

Detailed article on turbo compounding

USAAF Compound Engine Project

 

[Shortround6]

You Know a clam shell type bubble canopy like the F-16 has was technically feasible for a 1936 fighter. Are going to make some silly comment about needing fly-by-wire and advanced composites and CAD to make it happen? Obviously a 1936 clam shell bubble canopy wouldn't be the exact same design or materials. The same goes for a "turbo Spitfire"
And I do believe two-stage impellers and turbines predate 1940. I want to say the French for both of those but I can't remember.

We are confusing two different things. What is technically feasible from a materials and fabrication point of view and what is feasible practical from point of view of just fitting the desired "stuff" in the air frame.
By the time you get to 1945-46 piston fighters with high altitude engines the supercharger system takes nearly the same volume as the basic engine.
Even if you have the idea for such a supercharger and the materials to make it it won't fit in a Spitfire or even a P-51.
You might be able to build your prototype engine and fit it into a single seat fighter. But it won't be anything somebody would recognize as a Spitfire or P-51.
Engine text book of the time estimated a turbo or mechanical 2 stage engine for a 1000hp engine needed about 10 cu ft of space. A 2000hp engine would get some benifit of scaling but it was going to be closer to 20cu ft than to 10 cu ft.
What was not said was what altitude. The Super Allison, the P&W Sidewinder and the Wright turbo compound engines were made for higher altitudes than even the 2 stage Merlins and they need the space/volume to deal with the thinner air.
Once again the earlier simpler Allison than the H-1.

and no aftercooler or any ducting for an after cooler.

 

[tomo pauk]

Shortround6 described the V-1710H. Bell had a P-63 proposal for Wright turbo mounted behind the engine at ~60° from horizontal. Both of these fit in the same space as the regular V-1710 two stage.

SR6 described the V-1710E-27, not a V-1710H. It was Bell's XP-63H paper projest that was supposed to be powered by that engine. The E-27 will not fit in the same space as the regular V-1710 with 2 stages of supercharging, since there is another perhaps 1.5ft required for the power recovery turbine to fit, and the exit of the spent gasses also requires some free volume.
Added to this, the 2-stage supercharged V-1710 was already a long engine, longer than the 2-stage Merlin, let alone the 1-stage Merlin.

GE turbos had two major problems that impacted compactness.
1. Their impeller efficiency was god awful.
2. Turbine cooling.

Pretty much anybody else's supercharger fixes one.
Two can be improved by air-cooled turbine blades. BMW had some success with them in 1938. There were other methods to improve cooling that could be employed. Such as the "turbo Snout" used in the P-61C. Most of these methods require better coordination between GE and the engine and airframe manufacturers.

If you'd be so kind to post some info about the air-cooled turbine blades by BMW, that would've been cool.
List of companies that made 'bad' impellers, and further messed up the intake to lower the compressor abilities:
- P&W (rectified by the C series R-2800s of mid/late 1944)
- BMW (rectified by late 1942 801E that went nowhere, repeated the succes with 801S in late 1944 by that time it was too late)
- Bristol (rectified by mid/late 1944, for the Centaurus and 100 series Hercules)

There is no doubt that GE would've made a better stuff with more pressure by the military, as well as with more support by the military and NACA. As for the usage of turbochargers in the British aircraft, that ain't gonna happen unless indeed some kind of time travel is used.

The XH-2600 engine X-95 This engine had two 13in diameter impellers. The first stage had an eye diameter of 9.625 and a van height of 3in. 8.25in and 1.25 for the second stage.
The XH-3130 engine X-96

Thank you
Unfortunately, P&W's 2-stage superchargers once installed on R-1830s were about as good as other people's 1-stage superchargers, leaving out the question of just how good were the superchargers on these P&W engines.
FWIW, RR (and other companies) were free to look at Farman's 2-stage S/C as depicted in open press in 1937, or even the earlier devices on the Junkers and Bristol engines in order to make a 2-stage S/C even earlier.

 

[SaparotRob]

Time machine.

From page 443 of "Vees for Victory"
"V-1710-41 2550+ bhp, turbo-compound w/separate 2-stage S/C and 2-stage air-cooled turbine, 50% aftercooler and port injection, 1947.

Also on Page 280, short description. Based on the G-10 which was a modified E-30 derived from the E-27.
E-27 engine
View attachment 796412
Just take of the engine driven supercharger, replace the single stage aux supercharger with a 2 stage supercharger, replace the single stage exhaust turbine with a two stage exhaust turbine. Install an after cooler, install port fuel injection, already has water injection.

Easy-peasy to put in a Spitfire in 1940..

I was thinking Hurricane, myself. P-39?

 

[Reluctant Poster]

You Know a clam shell type bubble canopy like the F-16 has was technically feasible for a 1936 fighter. Are going to make some silly comment about needing fly-by-wire and advanced composites and CAD to make it happen? Obviously a 1936 clam shell bubble canopy wouldn't be the exact same design or materials. The same goes for a "turbo Spitfire"
And I do believe two-stage impellers and turbines predate 1940. I want to say the French for both of those but I can't

I was thinking Hurricane, myself. P-39?

With or without nose armor?