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ad First Flight, reserve parachute and 3 piece wing 29 Nov 2013 23:09 #79

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Hi Rick,

I'm interested to read about the wing's behaviour when you flew it at 70mph. I'm guessing the 'boink' sound you describe was coming from the upper surface of the leading edge D-section as the compression forces built up with speed.

I am vaguely hoping that I might be able to tow my CD behind the local sailplane club's Super Cub tug plane, which has a Best Rate of Climb Speed (Vy) of around 60mph (though I suspect sailplane tug pilots tend to fly faster on tow - 70-80mph?)

My existing plans are to use just two laminates of CF cloth (in +45deg & -45deg strips) in the leading edges, but I wonder now if I shouldn't take the weight penalty and use three layers for extra stiffness. How many layers of cloth did you use in yours? I've read that Steve Arndt has towed up at speeds in excess of 70mph without wing flutter or any other issues. Do you know how many layers of cloth Steve used?

Happy Christmas,

Phil.

www.flubag.ch/FLUBAG_Flugzeuge_Actual/PA...rmalChecklist_en.pdf - scroll down to the last page for the Super Cub speeds data.

From: This email address is being protected from spambots. You need JavaScript enabled to view it. [This email address is being protected from spambots. You need JavaScript enabled to view it.] On Behalf Of Rick Mullins
Sent: 24 December 2012 00:27
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Subject: Re: [Carbondragonbuildersandpilots] ad First Flight, reserve parachute and 3 piece wing

Thanks Jeri. Most of the flight I was flying an indicated 33-35 MPH. Without flaps I was getting stalls around 25. The documentation says it should stall at 22 so 25 without flaps sounds like it's in the ballpark. I flew it to 70 MPH and there I could hear my carbon leading edges start to 'boink" as they oil-canned. I suspect the spoiler would turbulate the airflow to the rudder, but this glider has a very large rudder... doesn't seem to be an issue. I never personally did any firing tests with this pneumatic rocket but there are videos here

www.secondchantz.com/

Merry Christmas and Happy New Year

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