Odd Supercharger Questions

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ClipperLuna
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Odd Supercharger Questions

Post by ClipperLuna »

Couple things I was wondering about how the superchargers are geared on the 3350. I saw a diagram somewhere that looked like some kind of planetary gearset is used. Is that right? Also, are the gears setup for reduction in low speed and direct drive in high, or is it direct drive in low and overdrive in high (or something else entirely)?

flapman
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Re: Odd Supercharger Questions

Post by flapman »

ClipperLuna wrote:Couple things I was wondering about how the superchargers are geared on the 3350.
According to the F.A.A. Type Certificate Data Sheet (TCDS):

Low gear ratio ("low blower") is geared 6.46 to 1 turn of the crankshaft.
High gear ratio ("high blower") is geared 8.67 to 1 turn of the crankshaft.
The propeller is geared to turn 7 for every 16 turns of the crankshaft.
ClipperLuna wrote: I saw a diagram somewhere that looked like some kind of planetary gearset is used. Is that right?
Here's an image of a supercharger gearing for a Turbo Compound engine. It does looks like at least some of the gearing is of a planetary design.

Image

Granted, the modeled engines in the A2A L-49 do not have Turbo Compounding, but I imagine some similarities in design exist between versions.
ClipperLuna wrote: Also, are the gears setup for reduction in low speed and direct drive in high, or is it direct drive in low and overdrive in high (or something else entirely)?
There is no direct drive of the supercharger. The supercharger is an aerodynamic device, and must rotate at speed to perform work. A supercharger spinning at propeller RPM just isn't going fast enough. Even direct drive from the crankshaft is insufficient.

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ClipperLuna
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Re: Odd Supercharger Questions

Post by ClipperLuna »

Yes, that's the picture I saw, but until now I could only find a low-res version of it. Thanks, flapman!

Kind-of looks like an automatic transmission, doesn't it?

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