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A new concept class of racing at Reno
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Re: A new concept class of racing at Reno
Is just me, or does that look like a puller prop bolted on backwards to be a pusher?
Met a really talented fabricator once. While showing photos of his handwork, there was a moped with a motor and prop on the back. He said the performance was well below what he had hoped to achieve. He had taken a regular prop and turned it around backwards. I pointed this out to him. He had no idea a pusher prop is different.
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Re: A new concept class of racing at Reno
The shape of a prop blade is optimized to either pull, or push. Although there are turboprops which can go into reverse pitch and back up, the blades are optimized to go one direction. Taking a puller prop and sticking it on a pusher application is effectively running the prop backwards. It will work, but not as effectively.
Another way to think about it is imagine if you took the wings on a Cessna 150 and flipped them over, so the top is now the bottom. It will still fly, but it won't create as much lift. I suppose this doesn't count with a laminar flow wing, but I've never heard of a prop shaped that way.
Thus exhausts my layman's understanding of wings. Experts, please feel free to correct me.
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Re: A new concept class of racing at Reno
An upside down wing (or backwards prop) can generate the same lift as right side up (up to a point) but generally generate more drag as they do it. This means more torque required to spin the prop at a given RPM and thrust, requiring more power from the engine, making for an less efficient installation.
How bad this is depends on the airfoil. A highly cambered (curved) airfoil will be the worst; a symmetrical airfoil won't care either way.
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Re: A new concept class of racing at Reno
Think I will hold out for the Jet Beetle Class...
http://www.ronpatrickstuff.com/
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Re: A new concept class of racing at Reno
What you want is this:
More detail on the power unit here:
Get old-time hot-rodders together and utter the name "Turbonique." The entire conversation will shift to legends and half-truths of the '60s company supposedly created by NASA subcontractors to create a consumer market for rocket technology. Now there's video.
But I digress...
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Re: A new concept class of racing at Reno
if you took the wings on a Cessna 150 and flipped them over, so the top is now the bottom. It will still fly,'71 S.D.1000, '85-'91,'94',95,'97-'99,'02,'04,'06,'08,'10,'13,'14 NCAR.
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Re: A new concept class of racing at Reno
Originally posted by L.E.D. View PostAn upside down wing (or backwards prop) can generate the same lift as right side up (up to a point) but generally generate more drag as they do it. This means more torque required to spin the prop at a given RPM and thrust, requiring more power from the engine, making for an less efficient installation.
How bad this is depends on the airfoil. A highly cambered (curved) airfoil will be the worst; a symmetrical airfoil won't care either way.
It means you need to have an engine running the opposite direction.
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