Dan wanted an automatic start timer that would start
when the aircraft started moving. The TTC airplane will get off
the ground in about 2 seconds and in less than 100 feet at half throttle.
The prop driven record is from a dead stop on the runway to 10,000 feet
or 3,000 meters in 91 seconds.

The usual way of doing this is tie the tail wheel to a post and
cut the robe with an axe while the engine is set to take off power.
Too much power and it will roll over due to 1000 foot pounds
of prop torque. So Dan needs  to practice this.

I am making the timer out of a $10 kitchen timer.
It has the usual key board found in all keyboards up to a full size
computer key board. It consist of printed metal pattern that is shorted
out by a conducting rubber button AKA the keys. The trick to trigger it
remotely
is;  solder some small wires to both sides of the pattern and short them
out
with a relay. Been used for years and I first used this idea back in
1975 to control an AADO printing desk calculator.

http://www.rotaryeng.net/RT1.pdf

Here are some pictures of what I have done so far. More later.
The little black and blue thing is the 3V coil relay.

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Here it is ready to go. When the audio plug is jerked out
of the connector the timer starts. It is necessary for the pilot
to note the time when he passes 10,000 feet. There is a gopro
camera  recording the instrument panel and the timer so
that is not necessarily needed. Just look at the video
it will show the altimeter reading  and the timer.
The top line is the time of day clock.

The bottom line is the time in minutes and seconds.

The middle line increments like crazy and it may be hundreds of seconds.
I suspect  it will be blur on the Gopro.

Paul Lamar

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