Wing hold down - falsifies

Thu Jan 15 10:14:38 AKST 2004

I was just going to reply when I saw Tony's note. I do like the idea of locking the wing with 1/4 x 20 nylon bolts, especially  in one of the wing adjusters. A doughnut of lite-ply would take care of the up and down slop.

My current preference is to put the adjusters in the wing panels. This allows the usual 4-40 $4000-screw in the wing and also the use of RC car-body style clips through the protruding adjusters inside of the fuselage.

E.

-----Original Message-----
From: discussion-request at nsrca.org
[mailto:discussion-request at nsrca.org]On Behalf Of Keith Black
Sent: Thursday, January 15, 2004 1:25 PM
To: discussion at nsrca.org
Subject: Re: Wing hold down

Bob's technique and experience is much like what I do.

I use two adjusters per wing and would be uncomfortable doing otherwise. You
can't count on the nylon bolt to keep the wing from rotating since the hole
in the fuse ends up being larger than necessary to allow for incidence
adjustment. Even if you tightened it down good it will still slip under
force, and you don't want to get it too tight with a nylon bolt.

>>1)  Will tightening the bolt put undue stress on the front 1/2 of wing or
> > will a washer eliminate this

I reinforced the inside of the root rib with lite ply and a 3/16 square of
aircraft ply for tapping to hold the screw. Then on the fuse I reinforced
the inside with a 1/8" lite ply square to keep the head of the screw from
pulling on the fiberglass wall, and to distribute the weight.

Pictures:
http://www.fototime.com/86170A44B86B557/standard.jpg
http://www.fototime.com/59CE12BA35FD91F/standard.jpg
http://www.fototime.com/72F598912096B5F/standard.jpg

On my first Aries (the last two pics) I had to place the screw almost up to
the front wing adjuster to have clearance for the retracts and it does
bother me somewhat that the front of the wing is more snug to the fuse than
the back. So on the second Aries, with fixed gear, I've moved the screw back
a little to help even the load, however I still wanted it to be forward of
the tank because I want to have easy access.

> >
> > 2)  How long do the bolts need to be to keep from backing out, and is
this
> a possibility.

Mine are about 1 1/4" long. I didn't want them too long because it's a
hassle to screw them in, but also didn't want them too short in case they
started backing out.

I use 1/4-20 nylon bolts that I picked up the hardware store and cut them to
about 1 1/4".  I also purchased some aluminum 1/4-20 bolts that would work
fine but I think the nylon ones are less likely to vibrate loose.

Only once have I had a bolt loosen, luckily it didn't loosen enough to allow
the wing to slip off of the anti-rotation pin. So, in this one case it was
good that the screw wasn't just *barely* long enough!

> >
> > 3)  Should the bolts be changed regularly to prevent fatique.

I've wondered the same thing. After 135 flights they still look as good as
new, but I do occasionally think about it. I try to always keep them away
from fuel. I should probably change them once a season.

Keith Black

----- Original Message ----- 
From: "Bob Pastorello" <rcaerobob at cox.net>
To: <discussion at nsrca.org>
Sent: Thursday, January 15, 2004 5:19 AM
Subject: Re: Wing hold down

> I've used this method many years, when access to a bolt head wasn't a
> problem.  I've always used the cheap Dubro black nylon bolts, cut to
length.
> My method is to put a 1/2" hardwood dowel, about 1/2" long, epoxied to the
> back side of the ply root rib.  Usually, I'll locate this as close (in
front
> or in back) of the wing tube area.  Drill and tap for the 1/4-20 bolt,
push
> wing on, mark inside of fuse, drill hole.
>     If the fuse side is flexing a great deal, I just put a 1/16" ply disc
> about 3/4" diameter, glued to the inside of the fuse.  Center drill as
> needed, and enlarge if incidence changes.  It also provides a good surface
> for the underside of the bolt head to grab.
>     Properly snugged, they never loosened, at least in my experience.
>
> Bob Pastorello, Oklahoma
> NSRCA 199, AMA 46373
> rcaerobob at cox.net
> www.rcaerobats.net
>
>
> ----- Original Message ----- 
> From: "Ed Deaver" <divesplat1 at msn.com>
> To: <discussion at nsrca.org>
> Sent: Wednesday, January 14, 2004 11:13 PM
> Subject: Wing hold down
>
>
> > Hey everyone.  Have always used the bolt in the wing drilled through the
> > tube.  Have decided to go with a 1/4" nylon bolt through the fuse into
> > tapped dowel.  Only using one wing adjuster aft, with a vertical slot in
> > this hole so bolt will be tightened down with wings adjusted.
> >
> > 1)  Will tightening the bolt put undu stress on the front 1/2 of wing or
> > will a washer eliminate this
> >
> > 2)  How long do the bolts need to be to keep from backing out, and is
this
> a
> > possibility.
> >
> > 3)  Should the bolts be changed regularly to prevent fatique.
> >
> > Am not interested in rubber band, wire ties ect.
> >
> > thanx in advance.
> >
> > ed
> >
> > _________________________________________________________________
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