Where does airspeed indicator come alive?

[RoyHelsing]

I have been working on taxiing my recently purchased Model 4 before i actually fly it. I noticed that the airspeed indicator does not seem to work at taxi speeds. I did some testing on it, and it seems to operate fine putting gentle wind into it - but not at taxi. I am wondering if maybe I have not taxied fast enough yet. I have taxied fast enough to raise the tail wheel, but suspect I am only doing about 15 to 20 MPH. Does anyone know if there is a speed at which the analog airspeed indicator comes alive?

[avidflyer]

I just looked at videos of my Avid and Kitfox 4 and the ASI seems to start to move as soon as I go to full power. JImChuk

[RoyHelsing]

so basically once you start to accelerate but not during normal taxi?

[avidflyer]

Guess I'll have to look next time I take the plane out. Here is a video from late last fall. JImChuk
Kitfox 4 on skis 11/22/2021 - YouTube

[RoyHelsing]

Nice panel, nice airstrip, nice plane! When you do the turn around, the airspeed does not move until your take-off acceleration. So maybe mine is fine. I will try to get closer to take off and see what happens. Thanks, I appreciate the input.

[airlina]

Nice panel, nice airstrip, nice plane! When you do the turn around, the airspeed does not move until your take-off acceleration. So maybe mine is fine. I will try to get closer to take off and see what happens. Thanks, I appreciate the input.

Roy, just a word of caution with this kind of high speed testing, -be prepared to go airborne! More than a few guys have wrecked airplanes during high speed taxi testing , when the aircraft departs mother earth and indecision results. Bruce N199CL

[RoyHelsing]

Roy, just a word of caution with this kind of high speed testing, -be prepared to go airborne! More than a few guys have wrecked airplanes during high speed taxi testing , when the aircraft departs mother earth and indecision results. Bruce N199CL

Thanks. Not the first warning of that I have heard, and havre taxied it enough now to see how easily that could happen. However, until the rudder responsiveness because a bit more reflexive (they are way more responsive than other tail draggers I have flown (mostly L19’s super cubs, and champs), and until I can figure out how to tell if I am on the brakes or not (that seems particularly tricky on this plane - I would rather just taxi and if I go airborne guess Iwill have to continue the take off. The airspeed indicator not becoming responsive in taxi is still a concern - I don’t want to go airborne without an airspeeed indicator - so I am going to have to push that envelope a bit. I do appreciate the warning, however.

[avidflyer]

If you get some 1/4" ID plastic hose you can check the ASI without damaging it. I would take a piece about 10' long, and slide one end over the pitot tube. Plug the other end of the tube and start folding up the tube while watching the ASI. Folding the tube increases the pressure in the line, and the ASI should go up. If you were to have a T in the hose connected to a manometer, you would get a reading and with that, you can check the accuracy of your ASI. I've found that most of our cheaper ASIs read high. Here is a link to an article discussing this. Airspeed Indicator Calibration (n56ml.com) He is using a real water column, a manometer is an electronic device that will do the same thing but easier. Any gas furnace installer will have one, and I got mine off ebay for about $30. Used this method and added labels to the face of the ASI showing calibrated readings, my ASIs in both planes are spot on according to GPS readings when flown in opposite directions and then average the speeds. JImChuk

[RoyHelsing]

If you get some 1/4" ID plastic hose you can check the ASI without damaging it. I would take a piece about 10' long, and slide one end over the pitot tube. Plug the other end of the tube and start folding up the tube while watching the ASI. Folding the tube increases the pressure in the line, and the ASI should go up. If you were to have a T in the hose connected to a manometer, you would get a reading and with that, you can check the accuracy of your ASI. I've found that most of our cheaper ASIs read high. Here is a link to an article discussing this. Airspeed Indicator Calibration (n56ml.com) He is using a real water column, a manometer is an electronic device that will do the same thing but easier. Any gas furnace installer will have one, and I got mine off ebay for about $30. Used this method and added labels to the face of the ASI showing calibrated readings, my ASIs in both planes are spot on according to GPS readings when flown in opposite directions and then average the speeds. JImChuk

Thanks. I did ther first part of that and the ASI seems fine others than it does not seem to come alive during taxi (say under 20 MPH). I’m beginning to think that is normal.