Fairey Rotodyne

[Mossie]

As the Jet Gyrodyne was a pusher, it was probably considered at some point. The pictures I've seen have passengers embarking using the port door, but nothings running. The one's that come to mind are those of the nurses, they appear to be embarking by the side and disembarking at the rear.

[jcf]

Random thought: on a layout like the Rotodyne's, and given a free choice of engines, wouldn't it be better to have pusher props?

There are three means of entry to the fuselage: two side doors at the front and the rear ramp. Having pusher props would mean the blades would be well out of the way of all three, with the tailplanes and fins dissuading you from walking out of the rear and turning forwards too close to the fuselage. However with tractor props you've got to walk dangerously close to them to use the front doors.

Pusher propellers are less efficient than tractor propellers because they are in the turbulent air coming off of the wing and nacelle. Tractor props are in clean air. The pusher arrangement also puts more strain on the prop blades, prop hub and gearbox. I don't see that it would convey any advantage to the 'Dyne. Also it would effect the wing design, CG location, engine location and the design and placement of the undercarriage and undercarriage bays. If you kept the engines in the same location then you'd need extension shafts to drive the props, which adds complexity and weight. You'd also need to incorporate some sort of separate cooling air system to cool the exterior of the engine case because you'd lose the cooling effect of the air off of the propeller. 

[jcf]

As the Jet Gyrodyne was a pusher, it was probably considered at some point. The pictures I've seen have passengers embarking using the port door, but nothings running. The one's that come to mind are those of the nurses, they appear to be embarking by the side and disembarking at the rear.

There's a lot of difference between the small pusher props mounted on the tips of the stub-wing of the Jet Gyrodyne and large props mounted mid-span on the 'Dyne wings. Those little props are in very clean air in comparison to what the installation would be on the 'Dyne.

[Mossie]

By considered, I meant briefly, simply because the configuration existed. All the development drawings I've seen of the Rotodyne have tractor props, even those that are a transition from the Gyrodyne.

[zenrat]

I had the door/prop interface issue with my Tinydyne.  Shortening the fuselage moved the side door in line with the prop.
I just did away with the side door.  Everyone enters and leaves via a door at the rear.

[Weaver]

Random thought: on a layout like the Rotodyne's, and given a free choice of engines, wouldn't it be better to have pusher props?

There are three means of entry to the fuselage: two side doors at the front and the rear ramp. Having pusher props would mean the blades would be well out of the way of all three, with the tailplanes and fins dissuading you from walking out of the rear and turning forwards too close to the fuselage. However with tractor props you've got to walk dangerously close to them to use the front doors.

Pusher propellers are less efficient than tractor propellers because they are in the turbulent air coming off of the wing and nacelle. Tractor props are in clean air. The pusher arrangement also puts more strain on the prop blades, prop hub and gearbox. I don't see that it would convey any advantage to the 'Dyne. Also it would effect the wing design, CG location, engine location and the design and placement of the undercarriage and undercarriage bays. If you kept the engines in the same location then you'd need extension shafts to drive the props, which adds complexity and weight. You'd also need to incorporate some sort of separate cooling air system to cool the exterior of the engine case because you'd lose the cooling effect of the air off of the propeller. 

That's true when considering the propeller in isolation, however when looking at the whole aircraft, removing the effect of the prop-wash scrubbing across a fuselage and/or wing can reduce overall drag. IIRC, the Do 335 was 10% faster on it's rear engine alone than on it's front engine alone. This would probably be of little signifiance to a Rotodyne-style layout, since all it would do is remove the wing from the propwash, but not the tail surfaces.

I don't know of any example of a pusher turboprop that has any additional cooling system for the outer casing. In some cases, namely those that use "reverse flow" engines like the PT-6A, they actually gain a small engine performance advantage by having a less convoluted intake path.

In any case, all of this is an efficiency argument, and it wasn't an efficiency argument that I was making: it was a ground safety argument.