ORIGINAL: jrpav1

Matt - judging by the pictures it looks like what he means is the stab + elevator pitch which would of course translate to stab incidence. With split elevators like we have on pattern planes, I always try to lock the elevators to some known point when I adjust the stab. incidence - I take the pushrods out of the equation because they can be slightly biased. If the elevators don't go all the way to the tip this is easy. I disconnect the pushrods, clamp the elevators to the stabs at the tips and take my incidence measurements. On planes that have full-length elevators I make a fixture that slides over the stab + elevator and hold the elevator in the same position on both stab + elevator halves.

While we're sort of on this subject, what has more effect, an incidence change or a control surface ''trim'' change? What I mean is, say you're trying to trim your downlines. You notice that you're carrying some ''up'' elevator trim to maintain SAL flight. You also notice that the plane pulls out of a downline more than you'd like (i.e you can't hold a downline for very long without ''doing something''). Now, if you increase the wing incidence to reduce / remove your elevator trim, how will it affect the downlines? Will that solve your problem? What if, instead of increasing wing incidence, you decreased the stab incidence (and neutralized the elevator trim)? What would the difference be with each of these methods? Is it sometimes beneficial to split the difference between incidence and control surface ''trim''? I think in some cases it may be, I'm just not sure what has a ''stronger'' affect and which one is more sensitive to speed changes. I would think that control surface trim is more speed sensitive but I'm by no means a Master in this area.

John Pavlick
Team Black Magic, Tech-Aero Designs