snips..

Exactly. It will always suffer from high disk loading at low speed. So does
the UDF. The advantage is since you can control the pitch you can optimize
the pitch and get more power from the engine and therefore thrust. The UDF
used either two counter rotating fans or fixed stators behind a single fan
to recover some of the rotational momentum imparted to the air. A larger
prop with fewer blades will be more efficient at low speeds. If you can save
enough weight by going direct drive, plus some configuration advantages with
a small dia prop, and the variable pitch advantage, hopefully can help
offset the loss of efficiency. Remember this will only work on a high speed
single seat design. You certainly would not want it on a STOL plane.
An aircraft capable of using such an arrangement will need the following
numbers:
GW:                 1000 lbs
Max Cl:             1.8
S:
 46.6 ft^2
Flat Plate:         .8 to 1 ft^2
Monty

Hi guys,
There is such a design as your jpeg file attached and that is the Mini-imp that needs 60 to 80 hp. Go to www.mini-imp.com
This would also make a great single rotor plane.
Regards Don

There is a two place Imp in the Dallas Area but noone I've talked to has been able to get any information on it including the
guy selling the single Imp info.  He has been trying to find it so he can take some dimensions off it.
Roger Robertson

 
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