Most of the polyhedral glider flyers in this area (including myself) mount a brass tube on the leading edge of the spoilers with torsioned music wire inside to hold the slats closed. Would this be a good idea with your system for the 2M, or do they stay closed OK without the added fuss and weight?

Would this be a good idea with your system for the 2M, or do they stay closed OK without the added fuss and weight?

From : Don Stackhouse

That's a nice way to do it, but I don't see any benefit to this in this particular case. The key difference here is that the 2M Chrysalis uses pushrods (capable of both pushing and pulling) to operate the spoilers, rather than cables (capable of pulling ONLY). When you rig the spoilers, just set the pushrods with a LITTLE compression in them, and they will hold the spoilers closed every bit as well as the torsion springs would. The big trouble with the torsion springs (or any kind of spring-closed, cable-opened system, which is why we didn't go with this type of system on the 2M Chrysalis) is that the spring force is greatest when the spoilers are open and the air loads against the cable are greatest (which makes life very difficult for the servo), and the closing force is least when you need it the most, to hold the spoilers closed.

One thing that would add less weight and expense than the torsion springs, although with a bit more cost, and would make the spoilers even more solid in operation, is to mount a small servo (HS-50's would probably be enough) out in the wing at each spoiler with a short pushrod, then couple the two of them together to the same channel with a "Y" harness. This would replace the tubing and long pushrods in the wing, and would add strength by eliminating most of the cutouts in the center section sheeting (other than a small hole to get the wires out). Leave them coupled for RES contests, but if you want a little more roll control authority for sport flying or regular 2-meter contests (and if you're very good at transmitter programming), put them on separate channels and arrange for one or the other to open at more than about 50% rudder throw. This will give you a sort of aileron effect. A number of full-scale aircraft, such as the Mitsubishi MU-2 and the Grumman F-14 Tomcat use this arrangement instead of ailerons. It's also used on quite a few airliners to assist the ailerons.

Don Stackhouse
DJ Aerotech