PDA

View Full Version : testing an airspeed indicator



KeithD
12-16-2015, 08:06 AM
Guys,
How would you test an airspeed indicator without installing it and flying it? That is, before going to all the work of installation, how might you test and calibrate the damn thing?
Thanks!

Dave S
12-16-2015, 08:20 AM
KeithD,

Got car or truck?.........the ASI just needs a ram port and static source.......Make like a Google car and put a mast on the roof (or hood) that will keep the temporary pitot tube (Diameter of the temp pitot tube does not matter) above and out of the car's affected airstream.....rig a static port of some kind and go find a deserted road on a calm wind day and have at it.

The calibration will not take into account position error of pitot and static ports on the airplane; but, you can certainly get an idea if the thing works:)

DS

avidflyer
12-16-2015, 09:17 AM
http://www.n56ml.com/airspeed_calibration/
Here is a link to how you can do it using a home made water column. I remember a Kitplanes magazine article from maybe 10 years ago showing the same thing. Jim Chuk

Dave S
12-16-2015, 03:23 PM
I like Jim's idea better than my "dynamic testing".......eliminates the static port variables and theoretically the manometer should be quite accurate....and, less trouble with law enforcement for testing the higher speeds:o.

DS

Micro Mong Bldr
12-16-2015, 05:45 PM
Who cares about the higher speeds? Just get the ground speed off the GPS. It's the bottom end that matters! :D

LSaupe
12-16-2015, 06:39 PM
http://www.n56ml.com/airspeed_calibration/
Here is a link to how you can do it using a home made water column. I remember a Kitplanes magazine article from maybe 10 years ago showing the same thing. Jim Chuk

Actually once set in equilibrium you would'nt even need to add anymore water, just raise one side to get the delta you are after. Easy then to "undo" the pressure by then lowering that side (can get data on the way up and way back down to check for hysteresis etc.)