RE: New airfoil for Bird of Time?
I am not sure if I agree with Dave's philosophy, although the results he achieved cannot be disputed. As he say's Lift = Drag but lift in level flight always = weight. (exactly) You cannot have too much lift or the model would go up like an elevator. The EXCESS lift is traded into speed, the modern sailplane gets from LIFT A to LIFT B (thro' sink) as fast as possible, burning off all that excess lift as speed. A model whose lift just about equals its weight will always stagger along on the verge of a stall. We have all seen flyers trying to stay up staggering along just on the stall, a bit of down elevator & the model shoots off & the lift piles in. With the Cof G in the correct place the model should fly with the tailplane at more or less zero incidence, flying with loads of UP or DOWN elevator will produce drag. The answer is to use an aerofoil that produces its lift over the estimated speed range & produces min drag. Unless you are using CNC milled wings to the exact design profile you are wasting your time anyway with ribs & a sagged covering. The QUANTUM leap in modern sailplane performance has come about due to the computer generated aerofoil design being transalated 100% into the actual wing & not a 50% near copy.
Posted on: 10/6/2011 2:49 AM by Author "colinusher" in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=10750945

RE: New airfoil for Bird of Time?
If you inspect the ORIGINAL Dave Thornburg drawing you will see details of a much narrower fuselage. (smaller frontal area) However if you are building as a slope soarer narrower means weaker and slopers do not usually have the luxury of a flat landing area. Other suggested Airfoils are S 3021, Eppler 193 Eppler 205. What is the point. If you are building a vintage glider build as per the original plan. Would you build an exact copy of a Type 35 Bugatti & fit a Rover engine. Note in Dave Thornburgs 1979 RCM article the leading edge shape. Colin Usher @ www.colinusher.info
Posted on: 10/5/2011 1:15 AM by Author "colinusher" in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=10749353

RE: New airfoil for Bird of Time?
The Bird of Time aerofoil is a Clark Y thinned to 9%. A reprint of the original article by Dave Thornburg c/w original plan is at the Plans Section of www.colinusher.info Note the details re the leading edge shape. Colin Usher Appleton UK
Posted on: 10/4/2011 2:54 AM by Author "colinusher" in the forum "RC Gliders, Sailplanes and Slope Soaring"
http://www.rcuniverse.com/forum/fb.asp?m=10747643

RE: Keil Kraft Phantom Plan
Phantom Mite Plan & Building Notes. Try www.colinusher.info Colin Usher
Posted on: 3/27/2011 3:16 AM by Author "colinusher" in the forum "Control Lines"
http://www.rcuniverse.com/forum/fb.asp?m=10425340

RE: SEAMASTER Plans?
Use the plans at www.colinusher.info and ask your print shop to scale them up to give the size you need. Or you can print them yourself on sheets of A4 paper. Scale up just the same. A bit long winded but free. Details on how to tile print on my site.
Posted on: 3/29/2010 4:38 AM by Author "colinusher" in the forum "Seaplanes"
http://www.rcuniverse.com/forum/fb.asp?m=9620508

RE: SEAMASTER Plans?
Yes I have a set of plans. go to a_c_usher@yahoo.co.uk Colin Usher UK
Posted on: 11/22/2009 1:25 PM by Author "colinusher" in the forum "Seaplanes"
http://www.rcuniverse.com/forum/fb.asp?m=9272272