Trimming Question

[Paul Lawrence]

MessageI had an Aresti that had a bad tendency of pulling to the left on vertical uplines.
After spending half the day adjusting the engine thrust with no luck, I decided to check the elevator halves. The left elevator was moving up more than the right. After evening the throws, it pulled straight up after that.
My Aresti also pitched to the belly upon applying rudder and in knife edge. I mixed in about 5% up elevator with the rudder and it would then knife edge all way across the field with only rudder. That was probably a band aid for a CG or incedence problem, but it worked.



  ----- Original Message ----- 
  From: Larry Diamond 
  To: discussion at nsrca.org 
  Sent: Thursday, May 01, 2003 5:11 PM
  Subject: RE: Trimming Question


  Dean,

  Thanks for the advise...I think I'm on the right track. As for the "spectacular horse power"...The Aresti has a real good power to weight ratio with this set up. Plane is under 5-1/2lbs. If I pull power, the nose will start to slowly drop at the top of the 1/2 reverse cuban 8 as the airspeed decreases.

  I got through the up/down thrust test on the trim chart and ran out of time. Seems ok through this part of trimming. I did note that I may need a little more right thrust as it requires right rudder after pulling to vertical about 200ft. Didn't notice a pitching tendency. I'll check it again and pay closer attention......

  I'm new at this, so I appreciate the responses...

  Thanks, 
  Larry K. Diamond 
  Program Manager, KEG 

  Phone:  (812) 634-4286 
  Pager:   (877) 575-4163 
  Fax:      (812) 634-4007 
  E-Mail:  ldiamon at kimball.com 

    -----Original Message-----
    From: Dean Pappas [mailto:d.pappas at kodeos.com] 
    Sent: Thursday, May 01, 2003 1:46 PM
    To: discussion at nsrca.org
    Subject: RE: Trimming Question


    Hello Larry,
    You should not be trying to trim out the pitch behavior with rudder in level flight, but in the knife edge and/or vertical down. Tail-heaviness makes planes pull to the belly both there and in level flight with rudder. You just might be tail-heavy, based on your statement that you have to make the looping portion of the 1/2 reverse cuban start. You are probably in the very smal adjstments needed neighborhood. Unless your horsepower is spectacular (it should with the combo you have) a normal plane will want to start to at least think of dropping its nose after the 1/2 roll on the 45 up.

    Check both knife edges and the up and down lines. If three out of four (it's not a vote) pull to the belly, then you are tail-heavy.
    Regards,
        Dean Pappas
      -----Original Message-----
      From: Larry Diamond [mailto:ldiamon at kimball.com]
      Sent: Thursday, May 01, 2003 10:13 AM
      To: NSRCA
      Subject: Trimming Question


      I am sorting out an H9 Aresti 40 that I intend to start with Sportsman until I get another plane sorted out. 

      CG appears to be very close. It holds a 45 degree upline straight and needs a touch of elevator to start the pull through the 1/2 Reverse Cuban 8. Inverted flight only requires a touch of down elevator.

      My tank location was modified from the intended location and is on CG, to be read, "The front of the fuel tank is about 1/4 inch forward of the leading edge. I have mounted a YS 63 and has unlimited vertical after 4 tanks of fuel. CG is currently located at 4" back from the LE per the instructions (aft range). This tank location result in outstanding ground handling on grass. Zero tendency to nose over, not even close...

      The problem is in level flight it pitches to the belly with rudder input. Made for an interesting landing when I corrected with a touch of rudder for cross wind. 

      Is this an incidence problem? I haven't tried a power off dive yet to check it out due to time. What else could I look for?

      Engine - YS 63 New (2 tanks for break in and 4 flights) 
      Prop - APC 11x8 
      Max RPM - 11,400 (slightly rich still) 

      Thanks, 

      Larry K. Diamond 
      Program Manager, KEG 

      Phone:  (812) 634-4286 
      Pager:   (877) 575-4163 
      Fax:      (812) 634-4007 
      E-Mail:  ldiamon at kimball.com 

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