Hi Uri,

The solution for a warning on air brakes unlocked prior to take off is quite
easy. Use a micro switch on the air brake handle and a pressure transducer
from a washing machine in series.
The pressure transducer is connected to Ptot with a restictor in the line.
The restrictor together with the volume of the pressure transducer will
cause a delay of several seconds before full Ptot is noticed.
The pressure transducer switches at about 80 km/h for increasing pressure
(at take off) and at about 40 km/h for decreasing pressure (after landing).
I use the same idea in the warning system of our new glider. Have a look at
http://home.wxs.nl/~kpt9/gear.htm , figure 5.

Karel, NL



"Uri Saovray" schreef in bericht
om...
So if we agree this is a good idea, my main question is the design of
the tow sensor:
1) It must be robust
2) It must not interfere with the hook mechanism (open spoilers AND
can't release???)
3) If it is magnetic - will it interfere with the compass? Does
anybody care?
4) A Large magnet at the end of the tow rope - will it survive the
fall to the ground (either on winch or from the tug
Ideas?

Uri
Eric Greenwell wrote in message
...
Uri Saovray wrote:
Speaking of simple warning devices:
How about a simple hookup to a horn which is activated when the
airbrakes are opened while the towhook is engaged (i.e. open spoilers
during tow)?
A microswitch on the airbrake levers would be the no-brainer part.
What about the towhook? Magnetic sensor? where? How? Other ideas?
Uri

This would be an easy addition to the typical gear warning system, with
the new switch simply over-riding the gear switch. Fixed gear gliders
would need to add a spoiler switch and warning buzzer.

Pilots concerned about warning proliferation could consider using a
voice chip to speak "Spoilers" and "Gear" for the two alerts, instead of
a buzzer. Voice chips are cheap and simple to use these days.