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Windfree-need info

Old 01-12-2003, 10:20 PM
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captjckirk-RCU
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Default Windfree-need info

I have recently acquired a Windfree sailplane, can anyone give me some information? When designed, elevator setting, flight habits, balance point [I don't have the plans]? Thanks in advance for any help you may have. Captjckirk
Old 01-13-2003, 12:51 AM
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Ollie
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Default Windfree-need info

The Windfree was designed by Rod Smith and was flown to a first place in standard class at the 1970 SOAR Nationals at Chicago in 1970 by Mark Smith (Rod's son). Mark flew the Windward at the 1969 SOAR Nationals so, I believe the Windfree was designed in late 1969 or early 1970.

For first flights, balance the Wind free at the forward end of the tow hook. The instructions say to remove one BB of nose weight at a time until you can't stand it. Then put one BB back. The CG should be adjusted to the pilots flying ability so, there is a range of proper CG locations. The elevator angle is determined by flight testing and varies a bit with CG adjustment. Test glide over tall grass for safety until the aproximate elevator trim is established. The initial test flying and adjustments should be done by an experienced glider guider.

The Windfree was designed for use on histarts and 6 volt winches. The wing spar and joiner wires are undersized by today's standards. When launching on a 12 volt winch it should be tapped up gently so as not to bend the joiner wires or fold the wing.

The Windfree was on of the first competition R/C sailplanes to win national competitions. It dominated the standard class competition for the first half of the 1970's. It is still a fine thermal soaring sailplane if properly adjusted, flown prudently and not abused.

At the 1973 or -4 Soar Nats in Chicago I watched Rod Smith flying his 2-channel Windfree at near the limits of vision with two minutes to go to the target time. Someone asked him what he was doing so high. He replied,"Selling sailplanes." Then he did a half loop and flew inverted for about a minute and a half. Just above landing pattern height, he rolled upright and was on the ground within seconds of the target time. I relate this story to drive home the point that it isn’t the complication of the rules or the sophistication of the equipment that counts in the final analysis but the skill of the pilot in trimming and flying that renders other considerations relatively unimportant.

In an earlier Soar Nats. contest I watched his son, Mark, resolve a tie in a fly-off round. Mark was also flying a Windfree. In the landing approach Mark touched down on the second of the target time and with a touch and go, became airborne again to land about 20 feet away in the middle of the maximum landing zone for a perfect score. He didn’t need spoilers of flaps to do it. It was that performance that prompted Soar to go from landing zones to a graduated tape for landing. This change in rules was solely to spread the best fliers scores so that fly offs wouldn’t be necessary.
Old 01-13-2003, 01:21 AM
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captjckirk-RCU
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Default Windfree-need info

Ollie, thanks for all the info, looks like it should be a fun bird to fly, I only have access to a high start, so should be ok,
Old 01-20-2003, 09:21 AM
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wildblueyawner
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Default Windfree-need info

captain,

I recently finished a Windfree (named it “Oprah” ) that had been sitting, about 80% completed, for years up in my attic. It gets sloped, but in an area with only mild breezes and good thermal activity.

You’ll enjoy this plane, it’s a no-hassle (albeit delicate) thermalling machine – On the 2nd day out I thermalled it so far up that it almost vanished for good.

Some setup details:

I've currently got the CG exactly 2-1/2" behind the L.E. at the root. Even though that's only 35% of chord, it indicates lift well and feels pretty good; probably still too stable, so will test CG at more rearward positions.

Washout starts at the T.E. taper break. Use about 3/16" - 1/4" measured at tip. Make sure washout of each panel is within 1/16" of each other. I've experienced no tip stalling tendency at all.

Elevator travel is +/- 3/8" measured at the stab root T.E.

Rudder travel is +/-15 deg, however I made the rudder much larger than the original design. With the original rudder, the plane seemed very sluggish in yaw; CG location may have been the problem.

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