| Author | Message | ||
     John McKiernan New member Username: Rockyjs Post Number: 7 Registered: 11-2008 |
I'm test flying a Wheeler CT with a rebuilt IO-540 and new panel centered around a Dynon SkyView. Testing on the ground with a manometer showed the Dynon and a supplemental airspeed indicator to be very accurate. In flight doing some GPS 3 leg speed runs I find the Dynon TAS is consistently 12-13 knots higher than computed TAS verified by the spreadsheet. For anyone interested here is a link to the spreadsheet for TAS calculations: http://www.ntps.edu/images/stories/documents/gps-pec.XLS The error is attributable to the static ports. The ports are located on each side approximately 6" forward of the baggage compartment aft bulkhead. They are flush with the skin surface and possibly sensing a slight vacuum in this area. Has anyone had a similar issue and any resolution to the problem? My next step is to disconnect the static ports leaving the line open in the tail section. | ||
| wayne norris New member Username: Wayne_n Post Number: 13 Registered: 09-2003 |
take some Elmers glue...put a dot of glue 1/2" ahead of the port hole. will set up a little turbalance over the hole. if it works then wipe off and use epoxy. if it doesn't you could take an xacto knife... trim a ramp into the fwd side of the holes. set the alt to zero while on the runway, as you take off..does the alt increase before you lift off? or buzz the rw and does it read zero plus the few feet you are above it? be sure to announce that you are making a low pass for alt. check!. | ||
| John McKiernan New member Username: Rockyjs Post Number: 8 Registered: 11-2008 |
Thanks Wayne, I've put a drop of hot glue in front but haven't had a chance to test it. Good idea about checking the altimeter on takeoff. I'll also try to get some test runs flown at a lower altitude and airspeed. Another option might be to add a small washer around the static port to create some turbulence. |