[NSRCA-discussion] Trimming question

Ken Thompson mrandmrst at comcast.net
Mon Jan 30 13:25:31 AKST 2006


Well Dean,

I guess I will have to check to see which one of my planes needs the most help in this area.  I'm pretty sure my new El Nino won't need this kind of help, but I do have a few sport planes that I'm always looking to improve.

C'mon nice weather:-)

Ken
  ----- Original Message ----- 
  From: Dean Pappas 
  To: NSRCA Mailing List 
  Sent: Monday, January 30, 2006 5:08 PM
  Subject: Re: [NSRCA-discussion] Trimming question


  Hi Ken,
  You're right, it will.
  The subfin or strake should run from well forward of the stab, to the back of the stab. Okay, right up to the tailwheel mount! While you are at it, add a ton of side area!
  By making it more difficult for air to flow toward and then around the bottom of the plane, the stab will see less airflow from the "top" that causes a positive pitch.
  This only happens when the side of the plane is presented to the wind: let go of the rudder, and the spillage around the fuse disappears. (At least it changes)
  That's why Nat has fixed so many belly pitches, over the years, with a dorsal (backside) strake, filling in the "hole" in the side area, in front of the fin. 

  Science experiment, anyone?
          Dean

  Dean Pappas 
  Sr. Design Engineer 
  Kodeos Communications 
  111 Corporate Blvd. 
  South Plainfield, N.J. 07080 
  (908) 222-7817 phone 
  (908) 222-2392 fax 
  d.pappas at kodeos.com 

    -----Original Message-----
    From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Ken Thompson
    Sent: Monday, January 30, 2006 4:36 PM
    To: NSRCA Mailing List
    Subject: Re: [NSRCA-discussion] Trimming question


    Hello Dean,

    This is why I read all of the list's posts...I like to learn new things.  

    The sub-fin would go where, under the stab or closer to the nose?  I would think the placement would make a huge difference in the effect.

    Ken
      ----- Original Message ----- 
      From: Dean Pappas 
      To: NSRCA Mailing List 
      Sent: Monday, January 30, 2006 1:53 PM
      Subject: Re: [NSRCA-discussion] Trimming question


      Hi Gang, Hi Ken,
      The enswer probably lies in a combo of what Lance and Ron offered.
      How much is your buddy willingg to cut or add to fix the problem.
      A ventral strake/subfin will be a great experiment, and I am sure that a bunch of us would like to hear the results.
      Raising the stab would be terribly invasive, and also interesting.
      Make sure the ship flies with a styraight elevator first.
      later,
      Dean


      Dean Pappas 
      Sr. Design Engineer 
      Kodeos Communications 
      111 Corporate Blvd. 
      South Plainfield, N.J. 07080 
      (908) 222-7817 phone 
      (908) 222-2392 fax 
      d.pappas at kodeos.com 

        -----Original Message-----
        From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of patterndude at comcast.net
        Sent: Monday, January 30, 2006 1:44 PM
        To: NSRCA Mailing List
        Subject: Re: [NSRCA-discussion] Trimming question


        Ken,
        Not always. In level flight the neg incidence will require up trim. In KE flight, the tail has an increased weighting in the balance of forces and this uptrim can be more than needed.
        --Lance


        --
        District 6 AVP 
        www.aeroslave.com

          -------------- Original message -------------- 
          From: "Ken Thompson" <mrandmrst at comcast.net> 

          > Wouldn't negative incidence cause it to push to the gear, not the canopy? 
          > 
          > Ken 
          > ----- Original Message ----- 
          > From: "Lance Van Nostrand" 
          > To: "NSRCA Mailing List" 
          > Sent: Monday, January 30, 2006 12:40 AM 
          > Subject: Re: [NSRCA-discussion] Trimming question 
          > 
          > 
          > > Not many responses to this one, but here's my thought. The wing incidence 
          > > is way negative and the CG is aft. I got myself into that situation once 
          > > and didn't catch it for a while. Inverted flight was fine but the plane 
          > > was 
          > > squirrely and the up elv trim was more effective in knife edge than level 
          > > flight, resultin! g in canopy pull. 
          > > --Lance 
          > > 
          > > ----- Original Message ----- 
          > > From: "John Pavlick" 
          > > To: "NSRCA Discussion" 
          > > Sent: Friday, January 27, 2006 10:31 PM 
          > > Subject: [NSRCA-discussion] Trimming question 
          > > 
          > > 
          > >> Ok here's a good one. The owner of the L.H.S. asked me what I thought 
          > >> about 
          > >> this and I couldn't come up with a good answer. He has a Hangar 9 Ugly 
          > >> Stik - the real big one. I can't remember exactly what it's called. Guess 
          > >> it 
          > >> has a gas motor in it. It's big. He says he has it trimmed so it will fly 
          > >> inverted with just a very slight bit of down elevator (almost none). Ok, 
          > >> so 
          > >> it's not nose heavy, maybe even a little tail heavy. Now, when he flies 
          > >&! gt; it 
          > >> knife edge (either side) it pulls severely to the canopy. I mean like it 
          > >> will fly a complete circle. It needs almost 3/4 down elevator to fly 
          > >> straight. It's beyond a mix - fix. He also says that it has a bit of roll 
          > >> couple when flying level (not knife edge) but it doesn't pitch severely 
          > >> up 
          > >> or down under these conditions. Any thoughts? I guess you can rule out 
          > >> C.G. 
          > >> because if anything it should pull to the belly considering how it's 
          > >> trimmed 
          > >> to fly level upright and inverted. I haven't flown it so I can't add too 
          > >> much more. He builds OK so I don't think there's anything way out of 
          > >> alignment, but again I haven't seen it yet so maybe there is. What should 
          > >> I 
          > >> look for if I get my hands on it to try and help him? 
          > >> 
          > >> John Pavlick 
          > >> http://www.idseng! .com 
          > >> 
          > >> -- 
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