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Touring Motor Gliders Association (TMGA)
  • Hoffman Pitch Question

    Ethan Graham

    Summary: Discussion about use of Hoffman prop and static thrust/RPM observations.

     Subject: Hoffman Pitch Question
    From: "Fred Bonar" <fbonar@
    To: <Taifun17E@yahoogroups.com>

    Have a Hoffman prop pitch question?


    17NT is running as of last night. New heads and cooling set up. Heads came up to 300 but the oil did not even get to minimum and the OTA was 48-50. May have to cut back some cooling in the winter and at altitude.

    But as we hoped the heads made such a difference that when checking static went to 2900 (supposed to be 2650 to 2700) and had plenty throttle left. Increased the pitch to max and ran up to 2600 with throttle left. Had a carb tuning issue so did not force beyond that and it was dark.

    Anyone with experience on the Hoffman at full pitch and over static rpm, what’s the long term effect?



    Subject: RE: [Taifun17E] Hoffman Pitch Question
    From: "Lessard, George (LLU)" <glessard@
    Date: 12/16/09 2:55 PM
    To: <Taifun17E@yahoogroups.com>

    Contact the factory authorized station at American Propellers in Northern CA. My guess is that you are outside of the envelope and may be on your own.

    Subject: RE: [Taifun17E] Hoffman Pitch Question
    From: "Fred Bonar" <fbonar@WcFM8TO82SnOkwNZmVxmxg0RqmRzvTHqKy4VTmuB7eNg1ALfpn7QdX9TMoybzsMVvFm7uEStMx69DEg3PQ.yahoo.invalid>
    Date: 12/16/09 3:39 PM
    To: <Taifun17E@yahoogroups.com>

    Will do that, thanks George

    Subject: RE: [Taifun17E] Hoffman Pitch Question
    From: "Fred Bonar" <fbonar
    Date: 12/17/09 11:20 AM
    To: <Taifun17E@yahoogroups.com>


    American had me send them the complete engine, prop and blade models along
    with the new HP and will work a solution with Hoffman. May be as simple as
    changing props to a longer wider one. Hoffman has a variety of blades that
    fit that hub....works for experimental but not type certified....just for

    Thanks Fred

    Subject: RE: [Taifun17E] Hoffman Pitch Question
    From: "Lessard, George (LLU)" <glessard@
    Date: 12/18/09 5:18 AM
    To: <Taifun17E@yahoogroups.com>

    sounds like a solution


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