Got the Velocity 20B back in the air on Monday for two flights of about 30
minutes each.  >

Congratulations Al.

Just one thing, are they coil packs I see on top of the engine?
If so please read Tracy Crooks email re operating temperature.  We don't
want another in flight engine failure, it rather spoils one's day.

Ian Beadle

Very good point Ian.
You are absolutely right. Here is a minor point on this subject.
I think Al is running a 2.17:1 PSRU so his RPM's may be less
than yours, hence the pulse rate will be lower. However I can't
say if it is low enough to keep the coils alive. We still need
to set up a pulse generator and measure the heat increase
on the coil surface as a function of pulse rate.

In the mean time and before he flies it again Al should built
a box around the coils and feed in some cold air.

Paul Lamar

Hi Paul
I rigged a circuit to test the coil pack with a 2.5 ms pulse at equivalent
of 9000 rpm.  At 14 volts the heat generated was minimal. After 1/2 an hour
the temperature rise was just noticeable using the finger test.
At 12 volts the spark was less intense.  With a one ohm resistor in series
it was also less intense.

The wiring on Al's alternator looks a bit odd. Shouldn't one of the wires go
to the light?

Ian

Was that the RX8 coils or the GM V8 Ls1 coils?

Well then I wonder why the coils are failing. Equivalent? Is that
9000 pulses per minute ... 150 pulses per second? What ignition
system are you using? I wonder if your ignition system assumes
a waste spark setup where it might be firing twice per revolution.

Perhaps it is a Chinese quality control problem.

I am also wondering if the type of high voltage spark plug
wire has anything to do with it. Some wire has resistance
to suppress radio interference.

BTW when you had a coil fail was that the leading plug
or the trailing plug? How well did the engine run?

Paul Lamar ...No rotor no motor.

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