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Mike Stevens

ELEVATOR deflection at high speed cruise

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I think mine rides too trailing edge high.  It must be about 3/8" above the faired position at high speed.  I'm considering checking/lowering my canard incidence.

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On 10/13/2019 at 5:47 PM, Mike Stevens said:

What are the fliers finding for elevator defection at their max cruise speed?

In order to answer this question in a useful manner, you have to discuss GW, CG location, which airfoil (GU or Roncz) and IAS. Without that, any comment will be meaningless.

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Marc is correct.  I just presented a basic response.  The above that I presented is at a CG of 102.8, GW of about 1255#, Roncz canard and roughly 190 MPH indicated.  I verified all the above, except I only have screenshots near 190 MPH indicated.

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58 minutes ago, longezdave83 said:

Marc is correct.  I just presented a basic response.  The above that I presented is at a CG of 102.8, GW of about 1255#, Roncz canard and roughly 190 MPH indicated.  I verified all the above, except I only have screenshots near 190 MPH indicated.

Now we're getting somewhere.

At almost the aft CG limit of 103", somewhat under design MGW and an IAS substantially higher than the design cruise speed of the airplane (remember, the Long-EZ was designed for an O-235 engine of 115 HP, so has a design cruise speed in the 120 - 125 KIAS range (call it 140 mph IAS), it's not at all surprising that the elevator would be reflexed up a bit. That's 50 mph over the design IAS, give or take - the elevator trim position will need to be higher than trail.

There are O-540 powered Long-EZ's and Berkuts that will run out of up elevator at max power, and will still be climbing even with the elevator deflected full TE up (at well over 200 KIAS).

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Thanks to all for your inputs. I went ahead and installed my canard tips per plans and will probably mod once I start flying.  Hopefully next summer. 

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