From: petera@bcrka398.bnr.ca (Peter Ashwood-Smith 1600361)
Newsgroups: rec.models.rc
Subject: Re: Great Planes Super Sportster 90/120 review
Date: 13 Apr 92 14:17:53 GMT
Reply-To: petera@bcrka398.bnr.ca (Peter Ashwood-Smith 1600361)
Organization: Bell-Northern Research, Ottawa, Canada

>    John Cowie Writes...
> I also agree with the problems on wire gear for this bird.  I'm wondering
> if I could get more detail from you on the aluminum gearing you used.  I
> have not gotten to the repairs on my wing, and this would be a perfect

   Ok, here goes.

  Basically what you are trying to do is build very rigid gear that will
knock off in the event of a seriously bad landing. The wheels/axels will absorb
most of the shock of normal landings. The idea is to make a T out of 1/4 inch
aluminum pieces with gussets at the top of the T to stop any sidways
bending. You need to have this welded by someone that does aluminum work. I
went to a local machine shop and the guy charged me 15$ to make a pair of 
these T's. I had to clean them up/polish them etc. but the bulk of the work
was done by the shop. These T's are about 6" long, 4" across the top and about
1" wide. All pieces are 1/4" aluminum sheet. Next you mount a pine block at 
least 1/2 thick by 6" by 1/1.5 " burried in the wing to act as a seat
for the top
of the T. This is mounted the same way as the old wire system but you must
make larger rib doublers to accomodate this piece. You must also be absolutely
certain that the angle the block sits at is exactly 90 degrees to the desired
angle of the landing gear since you cannot bend the T struts forward or back.
The axels are attached to the bottom of the T strut facing outwards and
the wheel
pants are easily attached with a couple of bolts and blind nuts running through
the strut. Finally 4 holes are drilled in the corners of the top of the T strut
to take #6-32 bolts which run through the top of the T-strut into the
wing mounting block and into blind nuts on the top side of the block. I use
nylon bolts to hold the struts to the blocks which will break if there is any
severe stress. One thing to keep in mind is that when the T struts break free 
the wheel pant may puncture the wing so a double layer of fabric on the bottom
of the wing above the wheel pant will make it less likely that the wheel pant 
will puncture both the bottom and top surfact of the wing.


            #6-32 blind Nut

           v-| |-v
             | |  
       +-----   ---------------------------+    <-- Pine Block
       |                                   | 
       |                                   |
       +-----   ---------------------------+
 ----------                            ---------- WING SHEETING -------
           +-  ----------------------+
           |                         |
           +-  ----------------------+
                 \ \   |   |   / /
                  \ \  |   |  / /
             /     \ \ |   | / /
             /      \  |   |  /
  #6-32      /       \ |   | /
 Nylon       /         |   |
  Bolt       /         |   |
             /         |   |
             /         |   |
            | |        |   |
                       |   |      /\/\/\/\
                       |   |     (        )
                       |   |     (        )    3.25->3.5 inch wheels.
                       |   |     (        )
                       |   |      \      /
                       |   | -----------------
                       |   | -----------------
                       +---+      /      \
                                 (        )
                                 (        )
                                 (        )
                                  \/\/\/\/  

  I'd like to come up with a simple modification to this scheme that has better
shock absorbing abilities, for example, cutting the base of the T
halfway up and
drilling two holes in each piece then putting music wire in the holes and then
reassembling the base. Anyone else got ideas on ridged gear struts?

  Peter Ashwood-Smith.