REFLECTOR: PITCH & ROLL TRIM

[Dave Nelson]

Re: REFLECTOR: PITCH & ROLL TRIMI also tried various techniques to stiffen the standard pitch trim spring setup before I gave up.  Part of the problem for me was that the standard installation took up room behind the instrument panel, which is why I worked hard to find an entirely different alternative.  

I've got almost 700 hours on my plane.  I started with a pure "standard" installation, went to a modified installation after a significant panel upgrade (which involved inverting the fiberglass spring and stiffening it), and finally, the Strong pitch trim system.  I've got close to 100  hours on the new Strong system, including dozens of instrument approaches (where you really learn if you've got a good pitch trim system!), and I'm extremely pleased with this new setup.  The factory systems never had the authority and fine control that my new setup does.  

If your setup is working for you, that's great!  Mine wasn't, and so I came up with this solution.  Your ideas + mine = more options for the rest of the community!

Thanks.

Dave
  ----- Original Message ----- 
  From: Stephen Vaughen 
  To: Velocity Aircraft Owners and Builders list 
  Sent: Tuesday, October 19, 2004 12:48 AM
  Subject: Re: REFLECTOR: PITCH & ROLL TRIM


  Dave,


  I broke a series of stock pitch trim springs before waking up in the middle of the night with the answer.  As with so many problems I've ever faced, the answer was relatively simple, and was staring me right in the face.


  The answer was to create a pitch trim spring which was a series of 2 bid layers instead of one solid fiberglass spring.


  In other words, imagine the stock pitch trim spring shape and size, but made up of 10 independent layers at 2 bid each.


  What happens is that the layers slide against one another and no individual layer gets over stressed to the point of breaking.  Realize that 2 bid of fiberglass can flex a lot farther without breaking than can a 10 bid layer.  A series of 2 bid layers can achieve the stiffness you want by just adding more 2 bid layers.


  I recall that I found the sweet spot at about 10 layers, 2 bid each.  No more broken pitch trim springs and I have full override movement with adequate stiffness.  You want more or less stiffness, add or remove 2 bid layers. 


  I mentioned to Scott Swing that I had conquered this problem on my plane, so I hope that the word gets around.  Scott asked me how I made it, and I told him that I started with the stock pitch trim spring, duct taped one side, laid up 2 bid, covered it with plastic, another 2 bid, another sheet of plastic, etc., etc.


  Come to think of it, it may have been 8 2 bid layers.  I'll count the layers later this week.


  I hope this works for you.  Regards


  Steve










    I agree that the factory pitch trim system leaves alot to be desired.  Last winter I worked with Alexis Strong (of Cozy fame) to engineer a system for my Velocity STD-RG based on his well proven design that's flying in dozens and dozens of EZEs out there.  I've been (slowly... very slowly) putting together an article to describe my results.  In net, working with Alex, we modified the design for my Velocity and I'm very, very pleased with the results.  I'll try to post more in the next couple of days if anyone's interested.

    Dave

      ----- Original Message -----
      From: Tom Martino
      To: Velocity Email List (E-mail)
      Sent: Wednesday, October 13, 2004 9:51 AM
      Subject: REFLECTOR: PITCH & ROLL TRIM


      I like most everything about the Velocity design except for the pitch and roll trim.  So I am finally doing something about it.  I am installing tiny trim servos in the elevator and one aileron and outfitting them with piano hinged trim tabs.  The wires will be run inside the torque tubes.  I am happy to be eliminating that clunky linear activator and the cumbersome fiberglass trim spring on the canard and the string & spring roll trim.

      Anyone else ever do this?

      BTW - I have forgotten to post the paint designs I promised . but it's been difficult to get my graphic artist to send me the digitals.  All I have now are large print-outs.  They should be coming soon.  

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