[SPAM] Re: [SPAM] Re: [SPAM] Re: No fixed tips?

[David Lockhart]

This past year I put about 500 flights on a pair of Vivats which have fixed tips.  The 3 years prior, I put about 1600 flights on a pair of EMCs which had the control surfaces go all the way to the tips.  Same servos, same linkages, very similar surface areas and control throws.  Both used 2C engines and similar softmounts.  I found the average aileron servo needed to be replaced (pots and gears) after about 250 flights on both planes.  I suspect the biggest difference between the servo life I see and Troy sees is attributable to 2C vs 4C.  FWIW - we are both using the same aileron servos and laser throw meters.

The theory about tip vortices putting extra wear on an aileron servo makes sense - but I tend to think it may be more/less of a problem on different designs.  I tend to think other factors may contribute less, equally, or more depending on the particular plane - softmount used, engine used, weight of control surface, control throw geometry, orientation of the servo pot, etc.

Regards,

Dave Lockhart
DaveL322 at comcast.net
  ----- Original Message ----- 
  From: vicenterc at comcast.net 
  To: discussion at nsrca.org ; discussion at nsrca.org 
  Cc: Rcmaster199 at aol.com 
  Sent: Sunday, January 30, 2005 3:58 PM
  Subject: [SPAM] Re: [SPAM] Re: No fixed tips?


  I agree with Matt.  I have done it in both ways and never had problems.

  Vince Bortone
    -------------- Original message -------------- 

    I have done it both ways and notice virtually identical performance as long as the aileron areas (as a percentage and planform) are unchanged. What I have found stops the snap accurately and repeatably is a light wing. Have not required servo pots in either type after 100's of flights. Don't know why some are losing servos after a few flights, but do know what works for me.

    Commercial jets flying at 600 mph and models flying at 100mph, don't have much in common.

    MattK

    In a message dated 1/30/2005 12:30:22 PM Eastern Standard Time, pattern4u at comcast.net writes:
      The current theory is that the ailerons all the way out to the tips, stop the snap more accurately.

      Eric.
        ----- Original Message ----- 
        From: Bill Glaze 
        To: discussion at nsrca.org 
        Sent: Sunday, January 30, 2005 11:33 AM
        Subject: Re: No fixed tips?


        Again, with the full-size:  Notice that such luminaries as Boeing, Douglas, et.al don't run their ailerons to the tips, but instead stop short?    As Troy and Doug have stated, the wingtip vortices generated are the reason.  I had a long discussion with Dick Hanson about this, and he stated that "it didn't make any difference on our models."  Well, from what Troy has discovered about aileron pots, it seems it DOES make a difference.
        Bill Glaze

        Troy A. Newman wrote:

          They don't fly the same....and the aileron thru the tip thing wears out servo pots faster. I flew a model this past summer and it went thru aileron servo pots in 50 flights. I normally get well over 100-125 flights. And this was a wood model so the vibration was better damped than a composite fuse.

          Wing tips have lots of turbulence coming off of them...then stick a aileron in this turbulence. NOPE not the best from an engineering standpoint. 

          The answer guys and manufacturers give is it snaps better. My answer is design a good wing and it will snap better. Copy a good wing and it will snap better.  The ailerons become more effective with the area at the tip....but I don't feel it helps flight performance. Aileron thru the tip is much easier and faster to build than a boxed in version. on the ARFy stuff its cheaper...this is the biggest reason I think its done.

          As for elevators without tips there are no references. And the same things apply

          All my models have them boxed and will have them boxed in.

          Troy
            ----- Original Message ----- 
            From: Tim Taylor 
            To: discussion at nsrca.org 
            Sent: Saturday, January 29, 2005 7:46 AM
            Subject: No fixed tips?


            No fixed tips at the end of the wing/stab seems to be the rage. Any real reason for this? I really don't care for this very much as it makes it harder to make sure your trim is right and the elev half's meet.


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