Superchargers serve a different function in aircraft engines than automotive......their purpose is to provide boost to maintain engine power at altitude, not to increase power as is done in vehicles. Some trivia for ya.....
This 17 minute "Air Forces" recruitment film made in '42 and featuring Lt. Jimmy Stewart has plenty of period footage. It's well worth a look for anyone interested in this stuff! http://www.youtube.com/watch?v=ZK-ODNKKLBo
Also...the whole damn industry; California became a hotbed of aircraft building and so had vast capacity for fabrication, casting aluminum, working plastic, machining, plating, etc. So...lots of good tech people, lots of engineering and improv knowledge, lots of capacity, and the boom and bust cycle of aircraft contracts often left capacity available...perfect atmosphere for aluminum widgets, cam development special parts of all kinds. The whole speed equipment industry was just a little wart on the side of the huge government funded air industry...
Yes, it was designed to give the engine more air at high altitude where air is less dense, but the supercharger increases power at all altitudes. They can't turn it off and on based on altitude. Now if the had the blower Mad Max had...
Many WW2 aircraft had multi speed superchargers and or dual stage.With a dual stage,one supercharger feeds the throttle with a steady 14 PSI. Then a second supercharger boosts it for power.Water cooled V-12 fighters by the end of the WW2 could see 45 psi of actual boost for combat emergencies.All US four engine bombers used a turbo and mechanical supercharger,also same for the P-38.German Mercedes V-12's had a hydraulic variable speed blower.Allison also used a variable speed blower drive and alcohol injection to control detonation. All superchargers were centrifugal designs.
In true Hot Rod fashion, Fisher Body in 1942 signed up to build two P-75 "Eagle" prototypes. Take pieces/parts from the P-51 Mustang, Douglas A-24(SBD), F-4U Corsair all in the mid engined,shaft driven prop layout of the P-39 Airacobra and stuff the most powerful liguid cooled engine available in it. The 2600 HP Allison V-3420 was basically two V-12's driving one propshaft.
Not 100% accurate. The big radials were supercharged to around 60" of manifold pressure at sea level. They used every bit of it on takeoff. As we all know, a non-supercharged engine will never exceed 30".
I have a pretty extensive hardbound collection of aviation history books, mostly WW2, and many autobiographies. One of my favorite books, though, is "China Pilot" by Felix Smith. Put it on your read list, you'll be glad you did. One of his best friends was the real "Earthquake McGoon", who was killed flying C-119's in relief efforts of the French at Dien Bin Phu. What an incredible book!
3 years ago at Carlisle I was buying a Model B fuel pump an old guy had in his "$1.00" pile. I was feeling guilty about it, and wanted to say "NO!! Here's $50"... Then I noticed his cap bore a CBI sevice patch. I was the FIRST PERSON EVER to notice that! We talked for about an hour; as a young officer, he had helped supervise thousands of Chinese laborers building the huge airfields in China that launched the first B-29 strikes agains the Japanese home islands. Fascinating and little known history by the ton. Pay attention to the geezers you meet...some of them are still ticking, and we still have the chance to hear first person hiostory for a few more years.
I remember you giving me the whole run down of the history of 'aviator' sunglasses and how they were specially designed for fighter pilots to allow unobstructed vision and as eye protection. Have you still got that old Omega (c.1957?) that you found in a pawn shop? (Yes, I do retain completely useless information!)
I always thought that the invention that counted most that was a biproduct of the war is the computer. One of the earliest computers was Norden sight used to accurately target bombs. Some 70 years on and I'm sitting here typing a comment on a website on a computer. My Dad always says, nothing excels technology quicker than a war. Great blog JB, i'll look into reading some of the books mentioned.
The Jalopy Journal
