Eagler's Nest

Airframes => Single Seaters => XL => Topic started by: Mrbill on May 01, 2018, 07:24:27 AM

Title: Help needed - Wing dihedral dropping
Post by: Mrbill on May 01, 2018, 07:24:27 AM

I’ve been trying to set the dihedral on my wing to 3 inches. However, every time I think it’s set, when I take the stand down it drops up to 2 inches.  I’m going to rope it up to the garage door track and see if this helps.  Any input would be appreciated.  Also, since I’m building in my garage, I can only do 1 wing at a time.
Thanks,

Title: Re: Help needed - Wing dihedral dropping
Post by: leshoman on May 01, 2018, 08:57:25 AM

rigging one wing at a time us possible but difficult because of flex and general construction strength of an ultralight.  i took elect conduit, 3/4 and 1” so they would slide inside each other and welded a nut on larger tube so i could adjust an lock in length. bent ends so they would fit in fuselage and wing, adjustable length struts. built 4 of them, moved to front yard and rigged it.  adjusted lengths till i got everything where i wanted it them used the conduit struts to build real strut

Title: Re: Help needed - Wing dihedral dropping
Post by: Mrbill on May 01, 2018, 09:15:24 AM

Thanks Les.  I think I understand. I just wish there was an easier way.

Title: Re: Help needed - Wing dihedral dropping
Post by: leshoman on May 01, 2018, 09:47:18 AM

if machine was inflexible like bigger ones it would be easy.  i tried several methods and finally gave up and went this way

Title: Re: Help needed - Wing dihedral dropping
Post by: CHARLES DEBOER on May 01, 2018, 09:36:57 PM

I built two adjustable saw horses.  Leveled the fuss. and attached wings at root.  Propped the outboard wing tips with adjustable saw horses (both wings at same time).  Leveled the wing and checked for washout and incidence.  Measure and cut struts.

Title: Re: Help needed - Wing dihedral dropping
Post by: Mrbill on May 02, 2018, 07:41:49 PM

Thanks Charles.  Any issues holding your measurements?  I basically did the same thing however, when it’s released it’s not holding.

Title: Re: Help needed - Wing dihedral dropping
Post by: CHARLES DEBOER on May 02, 2018, 10:40:19 PM

If you can measure the amount of sag simply extend the strut beyond the desired position by the amount of sag.  As long as you have the same amount of sag for each wing, don't worry about having exactly 3 inches of dihedral.  Leonard has said that we are not building high performance aircraft.  On something like dihedral, IMHO, if you are within 1/4 inch or 1/2 inch on each wing don't worry about it.  The speeds we fly will not make much difference.  Dihedral helps make for a more dossal aircraft and insures that the fuel flows towards the inboard fuel sump of your gas tank.

Title: Re: Help needed - Wing dihedral dropping
Post by: Mrbill on May 03, 2018, 07:11:10 AM

Thanks again Charles.  That was my next plan.

Title: Re: Help needed - Wing dihedral dropping
Post by: Leonard on May 03, 2018, 04:40:17 PM

Hi,
 Set the dihedral with the front strut and set the washout with the rear one.   Leonard

Title: Re: Help needed - Wing dihedral dropping
Post by: Mrbill on May 13, 2018, 06:49:37 PM

After several tries I believe I finally have it.  My thanks for all the input!