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Jch
05-24-2014, 12:24 PM
I took my SS7/Rotax912S/Dynon Flight Dek180 out for its first taxi today. Brakes were good, tail wheel and steering felt good. But when the GPS said I was moving along at 18mph the Dynon IAS said nothing. I have the basic Kitfox pitot tube, not an AOA unit. I disconnected the air tube from the back of the Dynon. I applied air to the pitot tube and heard and felt the air coming out of the other (Dynon) end. I was careful and the supplied air pressure to the pitot tube was very light...as I moved the (Dynon) end of the tube with air coming out close to the "In" port of the Dynon, the IAS moved up to 26mph or so. I have two static ports on either side of the fuselage. There is a "recalibration" function in the dynon under SETUP/AIRSPEED but that didn't help. This seems like such a simple system...how could it not work? I can call Dynon but with the Holiday it won't be until Tuesday and I'd like to keep working on this. Anyone have any ideas?

AirFox
05-24-2014, 01:41 PM
I experienced similar results when I first taxi tested my SS. I have the Advanced Flight Systems 5600. I was told that typical electronic airspeed indicators don't work til about 30 mph. That is what I experienced. My indication is spot on once I get to mid 20 mph. My plane wanted to get off the ground at 29 mph so be careful while taxi testing. Have fun!

Scott

jiott
05-24-2014, 03:07 PM
I have the same thing with my Dynon Skyview. IAS doesn't come alive until about 25 mph. Its just fine after that.

Jch
05-24-2014, 07:22 PM
Phew! An easy solution or explanation. Unlike the 25+ hours it took to trouble shoot the oil pressure sensor glitch. I'll taxi a little faster tomorrow. Boy the forum sure has been a time saver. Thanks.

jdmcbean
05-24-2014, 09:21 PM
That is correct. The pressure sensor for the AS will usually not come alive until mid 20's to low 30's. One way to check is to put a length of tygon tubing on the pitot tube and simply roll it up and pinch it off. This will put light pressure Into the system and should hold an airspeed.. If it bleeds off you might also have a leak.

Jch
05-25-2014, 10:12 AM
And just like that...I taxied up to 20-21 mph and on she came. ''Hey Dynon" If you put a sentence like "You may have to accelerate to 20+ to see the IAS with your new FlightDek D180" a person wouldn't have to remove his glare shield and disconnect the pitot tube, tubing, and connections unnecessarily. Ready for inspection in 3 days. Thanks Airfox, Jiott, and John M. for being there for a TeamKitfox member. I guess I am feeling some stress.JCH

Jch
05-25-2014, 06:05 PM
My apologies to Dynon. In their pilots users guide it explains "as airspeed increases from 0 knots, the indicator becomes active at 20 knots. The indicator remains active until airspeed drops below 15 knots" The airspeed is accurate up to 325 knots. Good to know.