PJFaller
Posts: 374
Joined: 8/11/2002 From: Daytona Beach, FL, Status: offline
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I have found that the L brackets work great. Here is the major problem that I have seen with the build on using the L bracket. Now speaking from experience I had both horizontal stabs blow off my 40% Extra 330, and the L brackets stayed in place and actually pulled the foam all the way through to the top of the stab. What ended up happening was I had the programming in the radio screwed up had the ATV's way down with a single servo on the stab half and I got severe flutter doing a high speed rolling pass. Airplane tumbled into the ground and was repairable and is flying today. So I have seen my own stab halfs come off. Here's what I think happens.....Ive built several cardens and two 40% Extra's. When guys build these things what happens is I think they do not get a 90 Degree angle between the root of the stab and the fuselage. The L bracket is the last thing I do on the airplane. I get the plate on the stab half as flush to the bottom of the stab as possible, but when I finally epoxy it in place, I but everyting up to the fuselage and set my incidence. Usually the stab plate that has the 6-32 bolt on it for the L Bracket comes out of flush just a little bit when curing so that the L bracket is at a perfect 90 degree angle to the fuse. I NEVER sand that plate flush. The reason being is that when you sand it flush and then you drive the 6-32 bolt in to attach the stab half, you pull the L bracket passed 90 degrees when you tighten it, and it always has a load on the 90 degree point. With flight loads it will eventually break. You NEVER want to have this point loaded because it will fail. Between doing that and driving a dowel in your stab tube, you should never have a problem. By putting a ply plate on the end of the stab and bolting it in with two bolts like Aerotech does, you are putting all the stress of the stab and incidence on one point of the stab. At least Cardens way if it is done right distributes the load from the leading edge of the stab throughout the stab tube. One point of failure should not destroy the airplane. Again all this being said, if it is done right. Just my two cents...take it for what it is worth, but when my failed, the L bracktes stayed on the fuselage and the foam pulled out...Again it was the worst flutter I have ever seen. My other comment to the guy building this particular 40% Extra, is be very careful about putting your rudder servos in the tail. The airplane is going to be hard to balance. I have my rudder servos just aft of the motor box, all my radio and battery equipment forward, and two 8611's in the stabs and I have my batteries in the forward part of the motor box. You might have hard time balancing the airplane set-up that way. This has been the case with both of my 40% Extra's. Good Luck and enjoy the build. Pete
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