Dethermalizing with R/C

During a long conversation with Don Broggini (of Stardust Special and Flying Wing fame) he pondered the possibility of an R/C DT but then dismissed it as impractical for normal flight regimes. He was amazed how quickly I found a reference to it on line.


In Radio Modeller Mar 1984, a diagram was published of an r/c operated dethermalizer to fit to to a fully flying stab replacing the usual horn. You fly normally, but if full up trim is selected, then full up stick applied, the stab went to 30-40 degrees up, causing a deep stall. The airplane then descended almost vertically, but horizontal, and fell more or less gently. Normal control could be recovered by reverting the stab to normal. I can not figure out how to make the linkages because the outlines are confusing. Has anyone made one? It could be done by using 2 servos, but this neat as it only used the one servo. I can email a pic if anyone can help. I want to try it as I want to fly in a clearing in the midst of trees, and this would be the way to "land"!

Take a look at the drawing I attached:

You need 2 of part A. SInce this part is fixed to the fin, it could be integral to the fin, and doesn't need to be this exact shape.
Part B has a tang that rides axle 1 between the 2 part A's. It also has 2 lower arms that engage the slot in part C. You could most easily make part B from sheet stock by using one "tang" piece and two "lower arm" pieces. Axle 1 is also the main axle/ carrythru for the stab.
Part C rides on axle 2, which wasn't clearly shown on the original. The slot in C, engages the 2 arms from B with a pin.
It's all just a mechanical way to provide extreme exponential.

 Thanks to the contributors at R/C Groups for providing this info.

Flying Stab Illustration

It goes through a 1/16" strut that goes from the top to the bottom of the fuselage at that point. Tube is CA'd to the 1/16" plywood strut. It pivots in the stab.

Eut
SAM Hall of Fame

The mechanics are built into the center section of the stab and not
very visible in the picture. When I frame the stab, aluminum sleeves are
installed for the pivot (5/32 ID or larger) and bellcrank (1/16 ID). The
sleeves extend out into the stabs for strength and set screw. The center
section has four ribs to support the bellcrank and keep the width 1" to
11/4"or the 1/16 wire will flex. Cut out the center section with a fine
saw. The aluminum tubes cut easy. Use brass tubing in the pivot.
I hope you can decipher my drawing and explanation. The Chief is a
great airplane. Walt.