Super charger

[raytoews]

Looking at the pics of the Bally Bomber, which is an amazing accomplishment, it looks like the unit between the prop and the engine might be a supercharger of some type.
Which got me thinking, Lycoming has that big flywheel on the front, turns 2700 rpm, replace it with a squirrel cage type fan, would it produce enough usable air to give a few inches of boost?
Relatively easy to build.
I remember reading way back when EAA was doing the mogas certification they had used an electric fan into the intake during ground runs and had seen "significant" increase in power.
I played with a Kcar with turbo many years ago and was impressed with the small amount of air pressure produced by the turbo which made a large difference in hp.
There was a discussion, I don't remember if it was here or on the Rvaitor about the ram air effect and it turned out to be not that big a deal.
I have an RV style carb heat and notice very little difference when I close off the ram air and draw air from under the cowling.
Turbo's are a small fast turning fan and we all know a big slow turning fan moves more air so maybe a 12 inch squirrel cage turning 2700 rpm might move enough air to make a difference?

[Sawdust]

Not quite the same thing, but....I read a story (with accompanying YouTube video) on a car forum about some guys who used four gas powered yard blowers to "supercharge" a little econobox car, and actually measured the resulting rear wheel power on a dyno. It really did measurably increase the power.

[eiclan]

just a quick reminder that horsepower costs,so driving a fan with the engine WILL incur a cost to the output.It is all about is the power in and out.This is why a turbo charger is more efficient than a supercharger as the supercharger uses engine power to drive it. Cheers Ross

[1600vw]

But nothing gives you that Hot Rod look better then a Supercharger...

https://www.youtube.com/watch?v=HRhDrt87ojY

[58boner]

Back in the 60's a dude named Smokey Yunick who also just happened to be a former B-17 Bomber pilot found himself to be a successful race car builder in the new burgeoning sport of NASCAR stock car racing. Having a dyno in his shop and an inquisitive mind he was known for his many...shall we say innovations that gave his cars an advantage on the track. He fashioned a supercharger that worked off of vanes he had welded to the spinning clutch assembly inside of the cars bell housing and recorded huge horsepower gains on the dyno but was unable to conceive a way to get the air to the air intake in such a manner that would elude detection of the tech inspectors. He did lots of stuff like that such as placing air pressure sensors in the wheel wells of test cars so he could collect actual data when he made changes to the wheel opening shapes on his race cars to reduce drag without visiting a wind tunnel.

[nrpetersen]

From basic physics, the name of the game with a fan type supercharger is how fast can you make the blades move. If you can get them to move 100 ft/sec say, then the maximum pressure gain per stage will be about 0.6 ft of water - or only about 0.25 psi (about 1/2 inch of mercury). At 2700 rpm your fan would have to be at least 8 inches in diameter (per stage) and you would be hard pressed to see the difference. But since the max pressure gain goes as the square of the velocity, the easiest thing to do is raise the RPM - a lot.

(I hope I did my estimates right........)

[1600vw]

Back in the 60's a dude named Smokey Yunick who also just happened to be a former B-17 Bomber pilot found himself to be a successful race car builder in the new burgeoning sport of NASCAR stock car racing. Having a dyno in his shop and an inquisitive mind he was known for his many...shall we say innovations that gave his cars an advantage on the track. He fashioned a supercharger that worked off of vanes he had welded to the spinning clutch assembly inside of the cars bell housing and recorded huge horsepower gains on the dyno but was unable to conceive a way to get the air to the air intake in such a manner that would elude detection of the tech inspectors. He did lots of stuff like that such as placing air pressure sensors in the wheel wells of test cars so he could collect actual data when he made changes to the wheel opening shapes on his race cars to reduce drag without visiting a wind tunnel.

As with anything if you want to do it right you better know what you are doing. So in building this truck I did a lot of research. Smokey did some great work with other parts of the engine like heads and intakes. I read a complete book just about him and what he did and did not do and why. Great reading.

Tony

[Skydriver]

( edit. . . ) This is why a turbo charger is more efficient than a supercharger as the supercharger uses engine power to drive it. Cheers Ross

A common misconception. It takes plenty of engine power to drive a turbo. Exhaust back pressure from the turbine restriction can easily be one atmosphere. 15psi back pressure on a 5" diameter piston is 294 lbs. of force pushing back on the piston. That is 145 HP at 2,600rpm. Yes, a centrifugal device is far more efficient than other designs but they all take gobs of HP to drive them. (numbers have rounding errors)

[raytoews]

On closer examination the mechanism on the front of the engine on the Bally Bomber is an overuning clutch. It would need it because the props are fixed pitch and an engine failure would produce bag of drag so the prop has to windmill freely, thus the need for the clutch.
Vey clever.
I owned a Terra Terratorn for a while and it had the same clutch. It worked fine but I removed it because we were concerned it would fail.

[Bob Dingley]

On closer examination the mechanism on the front of the engine on the Bally Bomber is an overuning clutch. It would need it because the props are fixed pitch and an engine failure would produce bag of drag so the prop has to windmill freely, thus the need for the clutch.
Vey clever.
I owned a Terra Terratorn for a while and it had the same clutch. It worked fine but I removed it because we were concerned it would fail.

I'm confused. I find that an unfeathered, wind-milling propeller produces high levels of drag. I had read that if you are unable to feather it, the next best solution was to stop the rotation by slowing to near stall or hope the engine seizes. I heard some trivia that in some instances a brake was installed to stop windmilling. Anybody else heard of brakes?


Bob