How could a design like this work

[skater]

A while back, there was a discussion about the fastest a propeller plane could go, and someone included this study of a hypothetical air racer that could potentially go faster than the fastest existing unlimited racers on a little over 2,000 HP.

http://aero-comlab.stanford.edu/Papers/AIAA-2000-4341-839.pdf

The strange thing about the design is that it uses a propeller mounted in the fuselage in FRONT of the tail empennage. I can't figure out a practical way to build such a structure. Either it would need structure that runs INSIDE the propshaft (I have seen some designs for front propellers with non-rotating noses that use that), or maybe a "ring" bearing, driven by a planetary gearbox where the structure runs in between the planetary gears (which would be a nightmare to design and I can't think of any precedent). Any other design would have to pass through the plane of the spinning prop.

Is there any other way to execute such a design? I'm starting to think this was an interesting aerodynamic study by people who gave no thought to how one would actually mechanically execute the design. They criticize Pond Racer, but Pond Racer was infinitely more practical than this.

[bflynt]

As a graduate student at Stanford I attended a presentation for this paper given by Eric Ahlstrom a short while after it came out. He was pretty clear the designs considered were dictated by the person who was funding the work. It sounded like the person was as interested in having something unique as having something fast. I remember that little side discussion specifically in reference to the mid body propeller like you asked about.

Does anyone know (and be willing to tell) who was funding the effort?

[RLind]

The AIAA paper mentions Sam Bousfield of Rennaissance Research: 'Inventor Sam Bousfield has developed several innovative methods to reduce the mechanical complexity required and has sponsored research into the performance potential of a body propeller equipped aircraft for both racing and civil use. Patents on these applications are pending,' on page 3. I assume that's the funding source but just guessing based on context.

Sometime in the early 2000s I saw a different mid body propeller application. It was a transport, not a racer. This other aircraft was going to have a unique hydrogen motor that was part of the 'secret sauce', I never saw how that aspect was supposed to work. This was also an inventor's pet project. I've honestly forgotten their name but I'm pretty sure it wasn't Bousfield.

[skater]

Sometime in the early 2000s I saw a different mid body propeller application. It was a transport, not a racer. This other aircraft was going to have a unique hydrogen motor that was part of the 'secret sauce', I never saw how that aspect was supposed to work. This was also an inventor's pet project. I've honestly forgotten their name but I'm pretty sure it wasn't Bousfield.

In trying to figure this out, I looked at the GE36 and Pratt/Allison 578-DX propfan engines, although I couldn't find many really clear cutaways. Both have fairly substantial structure behind the prop plane(s). The GE36 was powered by a turbine whose arc was just under the cowling, and the engine was able to carry static structure through the middle, as the gas generator axis did not extend back all the way to the turbine that drove the fan turbine. The 578-DX looks like it was probably just the equivalent of a large spinner for the rear fan.

Maybe something like the GE36 would work, or there was some sort of spur gear that drives the prop. Even more exotically, maybe one could hook up a gas turbine to a generator/alternator, and then build the propeller hub as something like nearly fuselage-diameter induction motor. The bearing would be unprecedented; any such system would have a rather low technology readiness level.

[Jukka]

Idea looks to be doing just fine. I wonder if Eric Ahlstrom is still on it.

https://en.wikipedia.org/wiki/Otto_Celera_500L