Airspeed on final

General
21

Vented to the cabin. Same as Kip.

22

Interesting. I tried that and got the same altitude and IAS errors as with the static being out at the wing. I figured there must be a slight negative pressure in the cabin.

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23

60 MPH. But there is a little “wiggle room” there, so 60 kts probably works too. But I wouldn’t want much more speed than that. Anything over 70 mph was float city. And yes, airspeed errors will make a huge difference in landing performance. Verifying accuracy of the airspeed indicator is something that should be done fairly early in the flight test process.

3 Likes
24

Joe’s definitely the authority; but FWIW here’s my procedure & numbers:

  • 80-70 KIAS on downwind (pull 1 notch of flaps between midfield and abeam the touchdown point)
  • Slow to 65 KIAS as I turn base, then pull full flaps
  • Slow to 60 KIAS turning final
  • 60-55 KIAS on final, depending on my glideslope. There’s a decent change in glide angle between these two speeds; its amazing how much more she “parachutes” at 52-55 KIAS (while still being comfortably above stall and easy to control).
  • 50-55 KIAS on very short final - just a quick cross-check as I look down the runway and pull power to idle shortly before crossing the threshold. Then everything is based on the sight-picture and pitch attitude.
  • After the flare I still float for a bit as I slowwwly increase the AoA, then touch tail-first (ever so slightly) right around stall speed. With moderate braking (smooth asphalt runway) I can turn off the runway at the 1500’ mark.
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25

I like to think that my pitot/static system is within 2% accuracy, even with my “rivet-vented” static system. Hopefully Bryan’s is accurate, too. I permanently bug 70 mph as a “minimum flare speed”. It seems that below 70 at idle, there tends to be more of a sinking tendency. Entering the flare at 70 may add a bit more float but it seems more natural. Going into shorter fields, I’ll carry a little power and be on the back side in the low 60’s. Get to five feet, chop and drop for minimal ground roll.
Additionally, I find that my full stall, three-point groundspeed to be about 55 mph at touchdown with zero wind.

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26

Your numbers look good Noel.

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