REFLECTOR: squat-switch adjust

[Al Gietzen]

During my 40 hour flight test, I thought my switch had lost its calibration
because I could not get my gear to retract even at 120 knots.  I pulled the
switch and checked the calibration and it was correct.  I found a pinched
pitot tube (tie wrap pulled too tight). 

And since my switch is located on the forward side of the canard bulk head,
the reference side of the switch is exposed to the nose pressure.  If you
look at the Velocity from the side, you can see that the pressure in the
nose area is going to be close to ram air - pitot pressure.

 

Either run a tube from the other side of the air pressure switch to the
cabin area or relocate the switch into the cabin, then the air speed switch
will have the proper static pressure reference.

 

Thank you; Ron.  That's it exactly.  I had recently calibrated it with a
water manometer to increase the setting a bit (to about 95) since I also use
that setting for warning the gear up when below the set speed. The gear
wouldn't retract until 110-120 kts.  It had worked OK before, but I also
recently installed the 'air dam' on top of the canard to keep the air from
spilling into the cabin; so now there is higher pressure in front of the
canard where the switch is.

 

Running the tube to the cabin side should be an easy solution.

 

Thanks again,

 

Al

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