I'm currently using a Vne of 125 mph flying my 4/1200 with 32 ft wing span. What's the groups thoughts on this? I'm currently cruising at 110-115 mph indicated.
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I'm currently using a Vne of 125 mph flying my 4/1200 with 32 ft wing span. What's the groups thoughts on this? I'm currently cruising at 110-115 mph indicated.
My first question is this: How accurate is your ASI? Second is: What does Kitfox say the VNE supposed to be on the Kitfox 4? JImChuk
My pilot handbook, if I remember correctly, says 120 mph for the standard model 4 1200 and 140 mph for the Speedster. I assume the airfoil shape of the tail surfaces of the Speedster handle higher airspeed a little better than the standard model 4's flat surfaces. James Thomas
My understanding is it has more to do with the thickness of the windshield material.
Thanks for the replies. My ASI is correct. I don't plan on faster than 120mph but when I got my kit vne was listed at 125 in my limitations (skystar). Of course we keep speeds down in rough condions.
You're probably right DesertFox4 about the windshield thickness. I just figured the airfoil tail surfaces might be less likely to flutter at higher speeds. I do remember that the Speedster called for a thicker windshield. I suspect we're both right. James Thomas
Just as a comparison, the Avid MK IV had a VNE of 135. They never did use any wood ribs in the tail feathers on the Avids. Avid wings are 2' shorter than the standard Kitfox 4. I have noticed the .060" thickness windshield start to buckle in at about 100 MPH though. JImChuk
My IV-1050 stated 125 mph.
My IV-1200 Classic has listed 140.
I agree with Steve, it is all about the windshield. The earlier kits had a thin (.062"?) Lexan (polycarbonate) sheet the w/s was made from. This would begin to stove in at around 115-120 mph. The later kits had a thicker piece (.087'?) or the molded acrylic piece from LP Aeroplastics which was much more rigid.
Is the 140 mph for the standard wing span Larry?
I don't know that the wingspan has any effect on the VNE.