EarthboundMisfit Posted October 11, 2020 Report Posted October 11, 2020 Hi all, Looking for feedback from other long body drivers regarding your aircraft's stab and elevator trim in cruise. In our Ovation with the STEC55x managing pitch, stab trim is always very nose down, yet elevator trim is slightly nose up. From the picture, you can see the elevator counterweight protruding downward in to the air stream during level cruise. Is this the same in other Ovations (or Bravos or Acclaims)? Appreciate any feedback. Hayden VH-OVH Quote
carusoam Posted October 11, 2020 Report Posted October 11, 2020 Same same... regardless of who/what is holding the elevator there... Experiment with moving Cg back, you may see less downward lift needed back there... PP thoughts only, not an aero engineer... Best regards, -a- Quote
PT20J Posted October 12, 2020 Report Posted October 12, 2020 Normal. The original design trimmed in trail. Lengthening the fuselage and adding heavier engines/props have necessitated changes to the trim system on later models. Js for instance trim trailing edge down. Long bodies trim trailing edge up. Skip 1 Quote
GeeBee Posted October 12, 2020 Report Posted October 12, 2020 Ditto! By the way my Super Cub flew the same way. Quote
JT Posted October 12, 2020 Report Posted October 12, 2020 Seems like this would have to be somewhat inefficient, no? Quote
GeeBee Posted October 12, 2020 Report Posted October 12, 2020 A little, but surprising little. I forget the number but it has be thrown out here. Quote
carusoam Posted October 12, 2020 Report Posted October 12, 2020 Consider it part of the design... it changes with WnB... To improve on that... Al Mooney last worked on a canard... It would be more efficient, but still have the variable with WnB... Best regards, -a- Quote
StevenL757 Posted October 13, 2020 Report Posted October 13, 2020 On 10/11/2020 at 5:24 PM, EarthboundMisfit said: From the picture, you can see the elevator counterweight protruding downward in to the air stream during level cruise. Is this the same in other Ovations (or Bravos or Acclaims)? Yes. It’s normal. Quote
PT20J Posted October 13, 2020 Report Posted October 13, 2020 10 hours ago, GeeBee said: Ditto! By the way my Super Cub flew the same way. Not surprising. I believe that the Super Cub (one of the most fun airplanes I've flown) has a very similar trim arrangement to the Mooney. Quote
PT20J Posted October 13, 2020 Report Posted October 13, 2020 6 hours ago, JT said: Seems like this would have to be somewhat inefficient, no? @GeeBee is right. The effect is very small. If it were not, Mooney would have fixed it long ago. Supposedly, Roy Lopresti analyzed this during the development of the 201 and decided it wasn't worth correcting. And he was looking for every knot of improvement he could economically get. Sometimes people think this deflection creates "trim drag." But that's not the major source of drag. The tail generates a tail down force to balance the airplane. This force adds to weight and increases the amount of lift the wing has to generate. The additional lift creates additional induced drag. This additional drag is the "trim drag". Any drag from the elevator being slightly out of trail is negligible by comparison. Skip 2 1 Quote
GeeBee Posted October 13, 2020 Report Posted October 13, 2020 10 hours ago, PT20J said: Not surprising. I believe that the Super Cub (one of the most fun airplanes I've flown) has a very similar trim arrangement to the Mooney. Almost except the trim handle is from a 57 Studebaker. 1 Quote
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