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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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