Paul,

         Have you seen any development, theoretical or practical, of the
         following:

         Aircraft have a unique opportunity for using a compounding
    turbine's
         shaft energy.  The cooling drag for an aircraft engine is about
         equal to
         the energy recovery from turbo compounding.  Both are 10-15% of the
         power
         output.  Connecting an exhausting fan directly to the recovery
    turbine's
         shaft could push the cooling air from the cowling at free stream
         velocity or greater.

         When the outlet velocity matches the inlet, cooling drag vanishes.

         The simplicity of a lightweight volute or shroud and an exhaust
    pipe
         could replace the complexity, weight, cost, and potential
    problems of a
         gear train and its safeguarding mechanisms.

         Thanks,

         Philip Groelz


         That is a real good idea Philip.
         Here is something similar.

         Paul Lamar ...No rotor no motor.

         This is an interesting idea and I have thought about it alot in the
         last
         few days. What I can't figure out is how to get the blower or
    sucker
         under the cowl. Too big.

         Then I thought well why not use an exhaust ejector AKA
    augmenter to
         evacuate the cowl and reduce the cooling drag. This too uses
    the waste
         energy in the exhaust to reduce the cooling drag.

         Nothing new here. The high velocity exhaust gases entrains air and
         sucks it out of the cowl. This is a direct way of utilizing the
         waste energy in the exhaust. Here are a couple of 3Ds. Main problem
         is it adds to the frontal area and therefore increase the drag on a
         tractor airplane. Probably will work fine on a pusher to reduce
    the
         drag. At least one pusher rotary is flying with an exhaust
    ejector and
         Charlie Airseman flew his Subaru powered Variez for a few years
    with
         one.

         Here are some old NACA papers on the subject.

         http://naca.larc.nasa.gov/index.cgi?method=simple

         1. An experimental investigation of rectangular exhaust-gas
    ejectors
         applicable for engine cooling Manganiello, Eugene J Bogatsky,
    Donald ,
         NACA Aircraft Engine Research Laboratory (Cleveland, Ohio., United
         States)
         NACA Report 818, 19 pp.

         2. Preliminary investigation of cooling-air ejector performance at
         pressure
         ratios from 1 to 10 Ellis, C. W. , Hollister, D. P. , Sargent, A.
         F., Jr. ,
         Lewis Flight Propulsion Laboratory, Cleveland, Ohio. NACA Research
         Memorandum
         E51H21, 23 pp. , 1951

         3. Preliminary air-flow and thrust calibrations of several conical
         cooling-air
           ejectors with a primary to secondary temperature ratio of 1.0 I
         :diameter
         ratios of 1.21 and 1.10 Greathouse, W. K. , Hollister, D. P. ,
    Lewis
         Flight
         Propulsion Laboratory, Cleveland, Ohio. NACA Research Memorandum
         E52E21, 26 pp. , 1952

    -------------------------------------------------------

    Bill James still flies a varieze with ejector/augmenter...

    Whole airplane,
    http://www.ez.org/feature/F0502-1/F0502-1.htm
    <http://www.ez.org/feature/F0502-1/F0502-1.htm>


    Under cowl pic with ejector:

    http://www.ez.org/feature/F0502-1/F0502-24.jpg

    A rather creative builder...


    Matt-

    On second glance it does not look like it meets the geometry
    requirement outlined by NACA of an effective augmenter. Here is a
    better one.

    Paul Lamar



In what way?  The exhaust stack terminates well short of the end of the
ejector.


Matt-

The dia. and lenght of the tapers needs to be in specific ratios.

see http://www.rotaryeng.net/how-to-cool12.html