I have tried RDS in F3B ships with good results. There are however a few problems. F3B control surfaces must be very ridid (remember Daryl P. recent post describing why he likes using 3 control surfaces per wing panel with 3 servos per wing panel for added control rigidity). The RDS system uses a steel rod in torsion which is somewhat flexible. (the control surfaces are spongy). I tried using 1/8" rod with brass tubing CA'ed over the rod. Rich Speroni machined some custom aluminum servo adapters that accepted the larger rod (I see that Harley now offers such an option). I also used a bearing at the sub-spar to add additional rigitity (also recommended on Harleys site). This did stiffen the surfaces to an acceptible level, but there was still some flex right where the rod bends 45 or 90 degrees. An all carbon rod would be ideal! The big problem with the 1/8" rod is that the pockects are too fat to fit into a thin F3B trailing edge (at least with my airfoil). I made carbon pockets from a mould, and took the pockets all the way to the skin, but I still could extend the rod back more than 1/2" into the TE.
I was never successfull using the 90 degree bend for the flap approach. The flaps were too spongy and when depolyed at high speeds there was not enough servo power to drop the flaps. Predictable flap control is absolutely critical! These are some of the problems I faced. I have not given up on RDS, and think that they are a great system when installed correctly. My next step would be to make a bent rods from carbon (much better in torsion than steel). But for right now for a rigid direct system it is hard to beat a servo arm hanging out the bottom, attached directly to a horn. I will gladly pay the drag increase to get the higher launch from a system that is more rigid. Gavin >>Hmmm... now there's a challenge if I ever saw one. How about you F3B types? The system isn't THAT hard to install. I would think a drag reduction like this would be attractive to any of you. Especially if it holds up to the rigors of F3B tasks. All I know is that when Bob and I retrofitted our planes with RDS, we'd had lots of time with the planes using standard linkage. When the change was made to RDS, a very noticeable increase in L/D occurred. Longer times became easier and search patterns were increased. I'm not talking F3B of course, just normal TD fun and contest flying. Bottom line; ALL of my planes do or will have RDS, period. Hmmm...maybe I'll put it in my new "Wedgie" . Just my humble opinion guys... Kevin Andersen<< RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
