• If You Are Having Trouble Logging In with Your Old Username and Password, Please use this Forgot Your Password link to get re-established.
  • Hey! Be sure to login or register!

Range Markings

hilllaguna

Registered User
Boise, ID
I am just getting ready to order instruments for my panel in my TCOW kit, and I would like to know how others have marked their airspeed indicator. Using the standard Piper manual, the VNE is 138, the top of the green arc is 110, and the flaps are 40-80. After talking with several experimental builders they have made adjustments to all this, and I get that experimental planes have their own characteristics depending on what you have built. But I tend to be one who pushes envelopes very little. For instance the flaps are significantly bigger on the TCOW kit, and I am thinking that dropping them out at 80 may not be a great idea (assuming that the flap range indicates full flaps). So I am thinking that I might white arc this at a top of 70.... While this is structurally a stronger AC than the original, keeping the 138 VNE seems prudent. But I would like input from others on how they approached this, and would just like to end this thought by stating my general perspective usually leans to the conservative in things.
 
For Our Certified Super Cub, we found that the STCs modified the airspeed markings. The 2000 lb gross weight increased the stall speed (at gross) and changed the maneuvering speed. Since we used all of the 18-150 upgrades we marked the indicator with the later 153 mph never exceed speed also.

Green Arc: 52 to 121 mph
Yellow Arc: 121 to 153 mph
White Arc: 50 to 85 mph
Maneuvering Speed: 103 mph
Red Line, Never Exceed: 153 mph
 
Remember that NO airspeed indicator markings are required for an experimental aircraft. You can temporarily mark a Vne for the inspection, then adjust as your flight testing progresses. Nothing needs to be set in stone at the outset.
 
Thanks

Thanks for the replies. The posting on the PA18-150 range markings was helpful. As yes, the FAA was the main issue to me. Having flow a lot of very early planes, give me a tachometer, altimeter, compass and an oil pressure gauge and I'm pretty good to go. You fly a plane, and depending on W/B, angle of attack, bank etc. the stall speed is a variable, so seeing the bottom end of an arc on a gauge is of relative value. Ditto Vne. If you are approaching that number, you likely have other issues on your mind like getting out of that dive without ripping the wings off the thing. The top of the white arc is good to know, but I am usually more interested in things not marked - your maneuvering speed, best glide. But what I really don't want is any surprises from the FAA at inspection.
 
Addendum to the previous

I got a call back from someone at the FAA that I have known for years - and perhaps those here already know this, but it was news to me, that the Piper Vne was related to the limits of the windshield, not structural issues with the wings or tail feathers.... who wudda thunk?
 
Back
Top