Message-ID: <056a01c42666$9de27440$6401a8c0@Davidscmptr>
Reply-To: "David Carter" <dcarter@datarecall.net>
From: "David Carter" <dcarter@datarecall.net>
To: <aeroelectric-list@matronics.com>
Cc: "flyrotary" <flyrotary@lancaironline.net>
References: <200404192243.i3JMhqI30111@matronics.com>
Subject: Re: AeroElectric-List: Re: Horse Power?
Date: Mon, 19 Apr 2004 18:32:44 -0500
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Hey, Old Bob,  about measuring torque in a planetary gear reduction system.

I have a 2.85 to 1 planetary gear reduction to hang on front of my RX-8
Renesis engine on an RV-6.  Have any idea how one could find out how to put
a strain gage on such a gadget to get torque?

The Lone Star Flight Museum at Galveston, Texas, has an excellent research
library with lots of tech data on WW II aircraft.  Maybe I could spend some
time in there and find out how they did that torque thing - if they had
started doing it by WWII.  I don't remember fighters having torque meters -
seems like that was something for the 4 engine transport and bomber guys
with a flight engineer monitoring lots of stuff.

David

----- Original Message ----- 
From: <BobsV35B@aol.com>
To: <aeroelectric-list@matronics.com>
Sent: Monday, April 19, 2004 5:43 PM
Subject: Re: AeroElectric-List: Re: Horse Power?


> --> AeroElectric-List message posted by: BobsV35B@aol.com
>
> In a message dated 4/19/04 5:33:02 PM Central Daylight Time,
> jmfpublic@comcast.net writes:
> I asked this question some time ago, and looked into strain gauges on the
> wing struts!  The strain gauge on the prop shaft scares me, as it could
mess up
> the engine, and sounds hard to design.  I dropped the whole idea in favor
of
> just completing the airplane.
>
>
> Good Evening Jim,
>
> If you really want to check the torque output, put strain gauges on the
> engine mounts.  Al Hundere made up a device to do just that on a Twin
Beech many
> years ago.  I understand that it worked OK, but needed a lot of TLC to
retain
> accuracy.
>
> I suppose you are familiar with the torque meters used on many radial
engines
> of the forties and fifties.  They worked by measuring the force on the
> planetary gear reduction system.
>
> More than one way to skin a cat.
>
> The nice thing about using a fuel flow to figure out what power is being
> developed is the simplicity of the idea.  The bad thing is that it won't
tell you
> if the engine is developing an unusual internal drag.  The engine could be
> tearing itself up and the fuel flow indication would not reflect the power
loss.
> A torquemeter will show that power output has been lost even though the
> engine is using the amount of fuel that it should be using to develop the
indicated
> HP.
>
> In smooth air, a change in airspeed gives an excellent indication of power
> output and, if the airplane has a fixed pitch prop, you can easily note
power
> changes by the change in RPM.  That is how Lindbergh did it.  Still works
just
> fine.
>
> Any help?
>
> Happy Skies,
>
> Old Bob
> AKA
> Bob Siegfried
> Ancient Aviator
> Stearman N3977A
> Brookeridge Airpark LL22
> Downers Grove, IL 60516
> 630 985-8502
>
>
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