Here is how to get off the ground in 150 feet guaranteed.
Use an old American V8 auto tranny  car along side the runway 150 feet
down with a right angle pulley in the center of the runway.

Take one rear tire off and wrap 200 feet of 3/8 nylon line around
the rim through the pulley and back to the main landing gear.

Take the other rim and tire off and anchor the hub with the five studs to a steel plate
embedded in concrete. This is necessary because of the differential action.
You then have 300 HP total. 200 in the car and 100 in the airplane with superb
low speed torque accelerating your airplane at 32 feet per second per second
or more. Have some one in the car ready to hit the gas when you are ready
to take off.

The tow rope auto release is tricky so if you are interested I'll do a dwg.

A lot of STOL airplanes use constant speed props to get good take off performance.
Low speed acceleration is everything. A fixed pitch prop sucks for this use as it
is horrible stalled at static RPM. It is not until you are going 60 to
80 MPH before it starts biting. Hence the junk car. Cheaper than a constant
speed prop :)

If you use a longer rope with the car at the other end of the runway you can use
it to help you climb to several hundred feet. This is how many sailplanes
are launched.
Paul Lamar

Glider guiders around here use a "cable tow" which is essentially a car
engine and auto trans on a stand with a big spool on the output shaft of
the transmission.  Hook up, start the engine, put it in Drive with the
engine at idle.  It takes up the slack, then just sits there, waiting,
with the plane on brakes.

When the Vipers are cleared to launch, advance the throttle on the plane
and on the tow motor.  When there is enough power to defeat the plane
brakes, release them and away you go.

For the ultimate in short-field tow, you can add an anchor and breakaway
on the tow cable and tail of the plane.  When you trip the breakaway,
there is a lot of energy already stored in the cable and your tow motor
is at a high power level.  This is what they do with catapults on
aircraft carriers (except they use a bolt for the breakaway,
specifically rated for the takeoff weight of the plane).

End of message.

Who knows? I DO! Sign your messages and don't delete author names !!!!
or you are out of here :) No more mister nice guy :)

Look up signature files in Google and use them.