I had an elevator related incident this weekend that I haven't seen before, especially on a DLG. After the HSS SC-2 contest Larry Pettyjohn and I were flying and comparing launch height on basically the same plane, one at 9.5 oz. and the other at 11.5 oz. I thought we were throwing at about the same force, so I suggested that we switch planes and compare launch height.
It's amazing how much 2 oz. feels in a DLG. You can really feel the inertia building up. Anyway, I was pleased with the launch height I was getting with Larry's 11.5 oz. plane, but I didn't like the crack I heard when Larry flew my plane. The elevator broke on the outside panel and the plane looped out of control. Larry quickly pulled flaps and got it down without any more damage. The autopsy reveled that it had failed during launch about 1" outside the mounting bolts and at the end of the carbon reinforcement. This is not a dynamically balanced stab, but it goes to show you the forces are pretty high. For the record, the servo (HS-55) and pushrod held up; it was the balsa and carbon that gave in. Dr. Drela's comments about flight loads are well taken, even in a 60", 9.5 oz plane. JE -- Erickson Architects John R. Erickson, AIA PS: Larry offered to replace the stab for me, which was appreciated. I was the one suggesting that we swap planes, yet he still felt responsible for the break. We need more of that integrity out on the field. > From: "Jason Werner" <[EMAIL PROTECTED]> > Date: Wed, 17 Jul 2002 11:24:20 -0400 > To: <[EMAIL PROTECTED]> > Subject: Re: [RCSE] servos on full flying stabs: thanks > > Oleg, > one other thing that everyone seemed to leave out. The elevator is a > "required" control. What I mean by that is that in the case of a > "situation", when you need to have the elevator move and move completely to > a desired position, having a small servo will not help here. For example - > you are diving your plane (of course not on purpose) and need to pull up. > If the servo is not up to snuff, then you are SOL. Flaps and ailerons can > have smaller servo requirements, normally if either are "overloaded" then > you simply get less throw and less motion. But neither are "fatal". Not > having enough elevator can be. RCSE-List facilities provided by Model Airplane News. Send "subscribe" and "unsubscribe" requests to [EMAIL PROTECTED]
