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

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