REFLECTOR: Calibrating the static port

Scott Derrick scott at tnstaafl.net
Tue Feb 24 14:23:28 CST 2009


Yes Al and thanks, a bit of pressure dyslexia!

If your altimeter shows you at a lower altitude than it should, your
static port is in a high pressure zone, which should respond to tape in
front of the port.

The reverse if it shows you at a higher altitude.

Sorry for the mix up.

Scott

Al Gietzen wrote:
>
> Scott;
>
> Straighten me out here:
>
> At the runway, Set your altimeter to field elevation.
>
> Now fly the airplane at cruise speed as close to the runway as you are
>
> comfortable. 50 ft is a good safe altitude.
>
> Note the altitude. Your altimeter should indicate 50 ft above field
>
> elevation.
>
> IF NOT:
>
> If your altimeter shows a lower altitude this means the static port is
>
> in a low pressure zone relative to the real or unaffected pressure.
>
> If the port pressure is too low, wouldn’t it be indicating altitude
> too high?
>
> Usually this requires a ridge behind the port to raise the pressure. Put
>
> a thin piece of aluminum tape right behind the port. Fly again. It
>
> may require multiple layers, it may require tape in front of the hole.
>
> Its a trial and error process.
>
> If it shows a higher altitude, the the same as above but start with the
>
> tape strip ahead of the port to lower the relative pressure.
>
> And vice versa?
>
> Mine was off 400 ft(high) at cruise. No wonder the ground seemed so low
>
> in the pattern! 3 layers of aluminum tape ahead of the static holes got
>
> it spot on, and my indicated airspeed now agreed with my GPS's computed
>
> airspeed(not ground speed!).
>
> Flying at cruise speed just above the runway requires calm attentive
>
> piloting. Don't do this as part of a known low pass with people
>
> watching and waving. Too distracting. Don't do it. This is flight
>
> testing and serious business. Have one person near the runway to
>
> estimate how high you are as you make the pass to verify your altitude.
>
> Scott
>
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