What of the Republic P-47 Turbo-Supercharger

[Husky]

As a kid reading Robert S. Johnsons' "Thunderbolt", I was captured by his exploits and the aircraft he flew. I really became fond of the P-47; I found out it was huge for a fighter, didn't climb all well (not counting zoom climbs), wasn't all that good maneuvering (depending upon profiles of flight). But, was extremely durable, had powerful armament, was very one of the fastest WW2 aircraft at 25K alt and above, could dive like a home sick demon (and not break apart)...and, the top European Theater aces (Gabraski, Johnson, Muhurin) all flew P-47's and survived.

I used to wonder why there where no engine exhaust stacks from the massive PW R-2800 engine on the P-47? Those two portals on either side just in front and a little lower of the wings was the exhaust? Huh? I gather those two ports where called "Waste Gates"? Doesn't seem right compared to other supercharged aircraft where their exhaust stacks are all but clear to the eye.

So, what's up with the turbo-supercharger system of the P-47? Why so unique? Why valuable?

 

[pbehn]

As a kid reading Robert S. Johnsons' "Thunderbolt", I was captured by his exploits and the aircraft he flew. I really became fond of the P-47; I found out it was huge for a fighter, didn't climb all well (not counting zoom climbs), wasn't all that good maneuvering (depending upon profiles of flight). But, was extremely durable, had powerful armament, was very one of the fastest WW2 aircraft at 25K alt and above, could dive like a home sick demon (and not break apart)...and, the top European Theater aces (Gabraski, Johnson, Muhurin) all flew P-47's and survived.

I used to wonder why there where no engine exhaust stacks from the massive PW R-2800 engine on the P-47? Those two portals on either side just in front and a little lower of the wings was the exhaust? Huh? I gather those two ports where called "Waste Gates"? Doesn't seem right compared to other supercharged aircraft where their exhaust stacks are all but clear to the eye.

So, what's up with the turbo-supercharger system of the P-47? Why so unique? Why valuable?

Dunno what the question is. A member here posted a picture of the P-47 turbo system, it is huge. taking the exhaust gases to the rear of the plane to the turbo and then the compressed air forward to the engine.

 

[Dash119]

Due to its size, the Turbo-Supercharger(Turbocharger in modern parlance) was located in the aft fuselage. The exhaust was ducted underneath the pilot to the Turbo-Supercharger and then exited underneath the lower fuselage. The compressed(boosted) intake air was returned to the Supercharger of the R-2800 via additional ducting underneath the pilot. All of the plumbing and ducting, as well as the Turbo-Supercharger itself, in part dictated the large size of the plane itself. There is a pronounced hump underneath the rear fuselage where the exhaust exited from the Turbo-Supercharger. The Waste Gates regulated the amount of exhaust gases sent back to the Turbo-Supercharger, and I believe all the exhaust escaped through the Waste Gates during engine start.

Instead of a two stage Supercharger , which was common on other high altitude fighters, the R-2800 in the P-47 had a single stage Supercharger which was fed by the Turbo-Supercharger. This is the same set-up that was used in the P-38 Lightning, but the Lightning used the Allison V-1710 rather than the P&W R-2800.

It was unique because I believe the P-47 was the only single engined Turbo-Supercharged fighter in the Allied inventory. It was valuable because the Turbo-Supercharger generated more boost above 25,000 feet, and didn't require some of the engine horsepower to turn it. There was some loss because there was no thrust generated by the exhaust gas, but it was more than made up by the higher boost.

 

[Husky]

Dunno what the question is. A member here posted a picture of the P-47 turbo system, it is huge. taking the exhaust gases to the rear of the plane to the turbo and then the compressed air forward to the engine.

You don't see the questions?

 

[pbehn]

You don't see the questions?

Well I presume that now you know how the thing works? The P-47 like the P-38 had an exhaust driven Turbo charger, which fed the single stage, engine driven supercharger. It was not at all unique as a system it was just the only major example in a single engine fighter. Here is a picture of it without the aircraft. from here Warbirds and Airshows - 2017 Pikes Peak Regional Airshow

 

[Husky]

Due to its size, the Turbo-Supercharger(Turbocharger in modern parlance) was located in the aft fuselage. The exhaust was ducted underneath the pilot to the Turbo-Supercharger and then exited underneath the lower fuselage. The compressed(boosted) intake air was returned to the Supercharger of the R-2800 via additional ducting underneath the pilot. All of the plumbing and ducting, as well as the Turbo-Supercharger itself, in part dictated the large size of the plane itself. There is a pronounced hump underneath the rear fuselage where the exhaust exited from the Turbo-Supercharger. The Waste Gates regulated the amount of exhaust gases sent back to the Turbo-Supercharger, and I believe all the exhaust escaped through the Waste Gates during engine start.

Technically got all this.

Instead of a two stage Supercharger , which was common on other high altitude fighters, the R-2800 in the P-47 had a single stage Supercharger which was fed by the Turbo-Supercharger. This is the same set-up that was used in the P-38 Lightning, but the Lightning used the Allison V-1710 rather than the P&W R-2800.

Not sure what this has do with the discussion.

It was unique because I believe the P-47 was the only single engined Turbo-Supercharged fighter in the Allied inventory. It was valuable because the Turbo-Supercharger generated more boost above 25,000 feet, and didn't require some of the engine horsepower to turn it. There was some loss because there was no thrust generated by the exhaust gas, but it was more than made up by the higher boost.

Thank you...looking for more of why. The P-47 had this large turbo-supercharger system that required a large airframe to support it. Big aircraft, very fast at altitude, incredible dive rates, 8 X .50 MG's, and not the nimble sleek fighters one thinks.

Again, why did Republic decide on this system of Turbo-supercharging?

 

[pbehn]

Again, why did Republic decide on this system of Turbo-supercharging?

They didn't, Republic make aircraft not engines, they used the engine systems that were available. Turbo superchargers have advantages and disadvantages.

 

[Husky]

Well I presume that now you know how the thing works? The P-47 like the P-38 had an exhaust driven Turbo charger, which fed the single stage, engine driven supercharger. It was not at all unique as a system it was just the only major example in a single engine fighter. Here is a picture of it without the aircraft. from here Warbirds and Airshows - 2017 Pikes Peak Regional Airshow
View attachment 588464

I'm familiar...thank you.

I see that now, looking at P-38 images...there's no exhaust stacks/ports from the engines.

From your image above; that system is very encompassing of an airframe; a lot of duct work (hot and cold), a fair amount of weight and fuselage growth.

Why this system over the P-51, Spitfire, BF 109, FW 190 supercharging systems?

 

[Husky]

Agreed, but they decided on how to use that engine.

 

[Dash119]

Instead of a two stage Supercharger , which was common on other high altitude fighters, the R-2800 in the P-47 had a single stage Supercharger which was fed by the Turbo-Supercharger. This is the same set-up that was used in the P-38 Lightning, but the Lightning used the Allison V-1710 rather than the P&W R-2800.

Not sure what this has do with the discussion.

I was just trying to point out that while it was somewhat unique, it was not the only case where a Turbo-Supercharger fed a Supercharger.

 

[Husky]

Undertstood

 

[Dash119]

From your image above; that system is very encompassing of an airframe; a lot of duct work (hot and cold), a fair amount of weight and fuselage growth.

Why this system over the P-51, Spitfire, BF 109, FW 190 supercharging systems?

 

[Dash119]

Sorry, for the last posting.

Loose nut on the keyboard.

 

[Husky]

Sorry, for the last posting.

Loose nut on the keyboard.

On the floor...go find it. LOL

 

[Dash119]

From your image above; that system is very encompassing of an airframe; a lot of duct work (hot and cold), a fair amount of weight and fuselage growth.

Why this system over the P-51, Spitfire, BF 109, FW 190 supercharging systems?

The Turbo-Supercharger allowed the P-47 to maintain more horsepower at the very high altitudes. It is only above 25,000 feet where the P-47 has a speed advantage over some of the other fighters. At 20,000 feet the P-51 is faster than the P-47, at 30,000 feet the opposite is true.

 

[Husky]

They didn't, Republic make aircraft not engines, they used the engine systems that were available. Turbo superchargers have advantages and disadvantages.

Still doesn't make sense to me; this engine is available to many aircraft; yet the P-47 utilizes this system of duct work and turbines to capture engine exhaust, cool and convert into supercharged air for the engine intake.

There are no engine exhausts headers on the the P-47 sticking out the side of the airframe, the exhaust is ducted to the turbo-supercharger, then there are controllable 'waste gates' of the turbo-supercharger.

 

[Husky]

The Turbo-Supercharger allowed the P-47 to maintain more horsepower at the very high altitudes. At those It is only above 25,000 feet where the P-47 has a speed advantage over some of the other fighters. At 20,000 feet the P-51 is faster than the P-47, at 30,000 feet the opposite is true.

Agreed. Big ass aircraft faster that all at 25K plus.

 

[pbehn]

Why this system over the P-51, Spitfire, BF 109, FW 190 supercharging systems?

The P-51A and Mustang Mk 1 had a single stage supercharger as did the early Spitfires. Later they had a two stage supercharger to give altitude performance. The P-47 and P-38 used an exhaust turbo for one stage and then and engine driven supercharger for the other stage, this works very well but is hard to fit in a single seat fighter. When Rolls Royce were asked to produce an engine for a high altitude Wellington bomber they discounted the use of a turbo just because of the difficulty in adapting it for anything else especially single engine fighters.

 

[Dash119]

Turbo-Superchargers of the day were quite large and not nearly as efficient as their modern counterparts. They are difficult to mass produce due to the close tolerances and special alloys required for efficiency. There was also a big demand for their use on Bombers.

 

[Husky]

The P-51A and Mustang Mk 1 had a single stage supercharger as did the early Spitfires. Later they had a two stage supercharger to give altitude performance. The P-47 and P-38 used an exhaust turbo for one stage and then and engine driven supercharger for the other stage, this works very well but is hard to fit in a single seat fighter. When Rolls Royce were asked to produce an engine for a high altitude Wellington bomber they discounted the use of a turbo just because of the difficulty in adapting it for anything else especially single engine fighters.

Now, this is interesting in understanding more.