Re: hello and Q

Thayer Syme (
4 Oct 1995 09:57:28 -0800

Reply to: RE>>hello and Q
I remember this as well. I think it was in reference to flying an authentic
SE-5a at Old Warden. they actually had to make their own gears to fly it
Thayer Syme

San Francisco

Date: 10/4/95 9:53 AM
To: Thayer Syme
In a message dated 95-10-04 08:46:17 EDT,
(James L. Cunningham) wrote:

>I have read in numerous places that there were
>> problems of some type with the Hispano-Suiza engine on that plane, but
>> never found out what that problem was. Do you know, per chance?

There was a very interesting article in WWI Aero a few issues back that
addressed this issue. Apparently, there were problems with the propeller
reduction gearing on some or all versions of the geared models. The
gearboxes had a useful life on the order of 5 hours or less. This problem
may have been related in some way to the particular contractor that built the
specific motor.

The author(s) of the article were involved in the restoration of a Hispano to
operating condition. In the course of this activity, they concluded that the
gears in their possesion, which they believed to be original, were of 2
different tooth profiles, and thus totally incompatible with each other.
Even though the gears could mesh and transmit torque, they would generate
excessive friction and fail prematurely.

I find it surprising that such a design flaw could exist in a developed
product, but I'm looking at this through an 80 year technological gap and a
peacetime economy. It may be that the gear handbooks of 1917 simply didn't
have enough information. Or that supply problems dictated workarounds.

I don't have the article handy and so can't give a reference. If there is
more interest, I'll track it down.

Eli Geher