This is not real automatic landing system so much as
it is an automatic flaring system.
Sharp makes a GP2DO2 solid state distance measuring sensor that can be
interfaced to the PICAXE It measures distances from 4 inches to 32 inches
with high rez. It uses the same principle the British Dam Busters
use in WW II to destroy German dams. It measure the angle the sensor
sees looking at a spot of infra red light reflected off the
runway surface.

You set up a decent rate of a couple hundred feet per minute
and let the auto flare unit take over at 32 inches. You might also
want to monitor the air speed so it does not flare after stall :)

The rest is software.

If you have a PIXAXE auto pilot altitude hold
you already have most of what you need. The idea here is mount
the sensor on the main landing gear axle and measure the distance
100 times a second and control the elevator to flare
the airplane. If anyone is interested in this let me know
and I will upload info from a book I have on interfacing
PICs.

This could be handy for landing sea planes on glassy surfaces
or land planes at night.

Paul Lamar ...No rotor no motor.

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