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How common are gear-driven superchargers in modern piston-engine aircraft, either alone or in combination with exhaust-driven turbochargers? What are some examples of modern aircraft that use them? Is it a technology that essentially went extinct in the aviation context with the last of the piston-engined fighters, bombers, and large airliners? Such that turbocharging alone (or other variants such as turbonormalizing) is the preferred technology for piston-engine aircraft now? (Besides the old standby of normally aspirated engines of course.)

How about belt-driven superchargers-- do any aircraft have them? If so, which ones?

Feel free to consider homebuilt aircraft, experimental aircraft, lightsport aircraft, and automotive conversion engines in your answer.

Edit: in light of a recent comment, I'll add that I'm asking about devices that are used at least in part to increase thrust and power by feeding pressurized air to the engine, rather than only to pressurize the cabin.

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  • $\begingroup$ Not really an answer to your question, but most pressurized pistons use a gear or belt driven supercharger not for increased power but for providing pressurization. It should be noted that most of these aircraft also have a ground normalized turbo-charger for power at altitude as well. $\endgroup$ – Noah Nov 1 '19 at 0:37
  • $\begingroup$ I'd say it's at least a partial answer, thanks! I didn't even consider that possibility though its kind of obvious in hindsight. $\endgroup$ – quiet flyer Nov 1 '19 at 0:40
  • $\begingroup$ Radial engines like the P&W R-985 contain a gear-driven impeller disc that spins at greater-than-crankshaft speed and centrifugally stirs the fuel/air mixture around in the intake manifold so that each cylinder gets the same mixture as all the others. However, by increasing the gear ratio it is possible to get a supercharging effect in addition to the mixture distribution effect. at least one Beech Staggerwing with the R-985 engine had the original fan ratio increased to 22:1 to improve hot & high takeoff performance. Don't know how common this mod was. $\endgroup$ – niels nielsen Nov 1 '19 at 4:43
  • $\begingroup$ @nielsnielsen that's worthy of an answer $\endgroup$ – quiet flyer Nov 1 '19 at 17:15
  • $\begingroup$ I would say that supercharging is much more simple solution than turbocharging. It has some use in cars as there is no turbo lag and that is not actual in planes. Turbocharging recovers otherwise wasted exhaust gas energy and supercharging just uses engine increasing consumption. Turbocharging technology has advanced a lot so it doesn't make sense to use supercharging' $\endgroup$ – Andrius Nov 1 '19 at 19:18
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Lycoming offered mechanical superchargers in some of their large 6 and 8 cylinder opposed engines like the GSO-480 but such engines have been out of production a long time.

I would say the only mechanical superchargers to be found on any engines manufactured today would be found on Russian or similar Eastern European radial engines like the M14P.

I'd be pretty shocked to hear of a homebuilder incorporating a mechanical supercharger, but maybe somebody will find an example. In any case, if you're going to do it, so much easier to do it with a turbo. The thing that makes turbocharging difficult to work seamlessly in cars, the power lag issue, isn't a problem with aircraft, so a turbo is a no-brainer that can be done by the homebuilder on just about any engine if they really want it. To incorporate a mechanical drive system on an engine not designed for it would be quite a daunting task.

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Radial engines like the P&W R-985 contain a geared impeller disc that centrifugally slings the fuel/air mixture around in the manifold from the carb out to the intake runners for each cylinder. This disc spins at greater-than-crankshaft speed and is intended to stir the mixture sufficiently well so that each cylinder is feeding on the same mixture as all the others. However, by changing the gear ratio it is possible to get a supercharging effect in addition to the mixture distribution effect. This was done in at least one instance in a Beech Staggerwing with the R-985 engine where the original fan ratio was changed up to 22:1 to improve hot & high takeoff performance. I do not know how common this practice was.

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  • $\begingroup$ The Reno Air Races, Unlimited Class P51s have stepped-up superchargers. Stock max manifold pressure is around 75 inches. Unlimiteds go as high as 150 inches or possibly higher these days. Lots of ADI fluid injection and liquid manganese in the fuel, though. $\endgroup$ – Walker Nov 2 '19 at 1:32

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