RV9a Performance: Need your x-check

[Richard Connell]

Originally Posted by blaplante

Run a 3 leg GPS test and plug it into the NTPS spreadsheet. [Search the forums...]
That will give you actual ground speed not some +/- 5% airspeed....

This ^^
This is the first step. Have you done anything non standard with the static ports?

[avrojockey]

Originally Posted by Richard Connell

This ^^
This is the first step. Have you done anything non standard with the static ports?

Richard and blaplante are correct...I had non-standard ports and there was almost a 10Kt error. 3-4 leg NTPS will reveal any error.

[blaplante]

And I guess we'll never know!

[Southern Pete]

The basic checks are,

1. Do you have the Van's static ports? If no then your static reference will account for most of the error. It is the outside shape that is critical, doesn't matter how you hook up to the tubes inside. Verify by using the GPS calibration method.
2. Calibrate your tacho and fuel flow.

If you are really turning the Sensenich prop 2400 or 2500rpm and have all your fairings installed and straight then you should be achieving close to Van's posted speeds.