Pusher prop Vs tractor prop

[18-Wheeler]

There's a debate on another aviation (model) forum about which is more efficient, a tractor-type or pusher-type prop arrangement.
All things being equal, (fuse & wing aero drag, engine & prop efficiency, etc) which is going to make for a faster aircraft?
Pushers are supposed to make more thrust standing still, but no more or less than a tractor prop at speed, or so the argument went.

[Ultralights]

pusher? as the trust isnt creating drag by pushing against leading edges of the airframe/wings.

[Flying Binghi]

...which is going to make for a faster aircraft?


I guess the proof is in the pudding - What is the fastest prop driven aircraft. Pusher or tractor ?

If yer believe wikipedia -
Fastest propeller-driven aircraft - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Fastest_propeller-driven_aircraft)




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[18-Wheeler]

I don't think it's that simple.

[barit1]

I believe the Cessna 336/337 performs better with the front engine shut down, compared to rear engine shut down. Tends to confirm Ultralights' post.

[Jane-DoH]

Pusher seems to be more effective as the flow from the prop isn't blown over the wing.

[Ptkay]

I guess the proof is in the pudding - What is the fastest prop driven aircraft. Pusher or tractor ?

What is the fastest commercial and mass produced prop aircraft?
Pusher or tractor ?

Piaggio P.180 Avanti - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Piaggio_P.180_Avanti)

Beechcraft Starship - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Beech_Starship)

[By George]

My understanding is the pusher is slashing away in disturbed air from the trailing edge of the wing and thus is down a little on effeciency. I also think it's the reason for that terrible "band-saw" noise they all make. The P166 and C337 sound like fornicating bumble bees.

[decurion]

"Pusher propellers were chosen to allow an undisturbed airflow over the wing so as to contribute to maintaining laminar flow over as large a portion as possible of the wing. An additional advantage is a drastic noise reduction in the passenger cabin. The aft position of the engine/propeller assembly also contributes to reestablishing the relative position of the C.G..

A side benefit of pusher propellers is that engine exhaust gases impinging on propellers blades make a blade de-icing system unnecessary."

Taken from: “PIAGGIO AERO INDUSTRIES: A LONG HISTORY OF INNOVATION”, AIAA/ICAS International Air and Space Symposium and Exposition: The Next 100 Y 14-17 July 2003, Dayton, Ohio

[DTY 116.4]

I seem to recall that when doing C of A single engine climb performance checks in the Cessna 337 many years ago, the aircraft climbed considerably better on the rear engine than on the front one. The reason put forward was that the disturbed air behind the front prop reduced the efficiency of the wing.

DTY

[Checkboard]

As a designer you have a choice:

Have the prop operate in clean air, and the wing behind it in disturbed air, or
have the wing in clean air, and the prop behind it in disturbed air.


Pusher prop designs are generally that way because the designer thinks that they have a very good, clean, laminar flow wing - and to maximise that efficiency they want the prop behind.

For something like the Piaggio Avanti, it also moves the CofG back, giving a nicer cabin, and getting the prop out of the way of the cabin (easier entry, and quieter operation).

[Dont Hang Up]

Another efficiency argument. The rotating wash from the front prop creates a sideways push on the vertical stabiliser which has to be trimmed out by the rudder. That means extra drag.