ContestID67 wrote:
I am in the midst of a project to install a gear/airbrake warning
system on my glider based on the built-in capability of my Cambridge
302. This system is better than the simple "airbrakes open, gear up"
warning system (http://www.wingsandwheels.com/pdf/gear%20warning.pdf)
as it also alerts the pilot to "airbrakes open on tow".

My "sensors" will be strategically placed reed switches and associated
magnets (and tefzel wire of course). My primary question revolves
around how to do a pre-flight test of the system.

From the manual...

"Warnings depend on presence or absence of airspeed as well as the
switch contacts. Here
is the logic: Unlocking the airbrakes connects pin 7 to ground. When
airspeed rises above 25 knots, the
alarm sounds. The alarm is cancelled when the airbrakes are locked.
During flight with the
landing gear retracted, unlocking the airbrakes connects pin 7 to
ground and sounds the
alarm. Lowering the landing gear opens the connection between pin 8
and ground and
cancels the alarm."

Reading from the above it would seem that the alarm system is totally
inactive until the GPS indicates I am moving 25+ knots. If so, how
can I test this system on the ground? Anyone else install this system
and have any experience? This weekend I will experiment to see if
the 302 programming is smart enough to allow testing while I am
standing still.

Thanks, John DeRosa


Connect a large syringe (ideally with a ballast volume) to the pitot
tube system and use this to carefully increase pressure.

This feature of the C302 is very nice.

Darryl