Conference vmszoo::rc

    	Well I guess an update is in order. The club meeting has come
    and gone. We didn't bring the ships but do plan to for the next
    meeting. To date my buddy plane has had the wings joined and cap
    stripped.  Last week monday was snowed out. Last night was a different
    matter. We got three good hours of building done. I was able to
    catch up with my partner except for the cap strips. So, to date
    both wings are sheeted and both fuse's are app 70% completed. 
    We made and installed the wing bolt hold down plates for both
    ships last night. Our plans are to install the torque rods and trailing
    edge centers and fiberglass the wings next week. If we get to it
    we will bolt the wings to the fuses also. A change in the design
    was agreed upon last night. We are going to go to 1/4 inch wing
    tip blocks rather than the 1 inch we had originally wanted.
    This is ti reduce tip weight and to shorted the wing down to 59
    inches. Still at 59 " the wing area will be 724 sq's. That's not
    bad. The thickness of the wing came out at the 2 1/4 inches we 
    wanted. With a root cord of 12.5 inches that gives us a 18% wing.
    At 724 sq's and an 18% wing we will be displacing quite a bit of
    air.
    
    						Tom

    
    	Well this project is still going, for those that thought I forgot
    about it. The construction has slowed somewhat but I suspect that
    it will pick up this coming monday.  The Torque rods are in and
    all of the other aileron parts cut. Both ships have large trailing
    edges of app 1/2".  As we looked over the balsa wood for a good
    stiff piece of 1/2 inch material I became clear that there wasn't
    any.  To attain the desired stiffness we laminated two pieces of
    3/8 by 2' trailing edge stock. These were in turn ripper on a table
    saw removing app. 3/8 of an inch of material from the thinner trailing
    edge part. A second rip cut was then done on the leading edge side
    of the aileron that yielded a piecs of stock 1 1/2 inches in width
    and 1/2 inch in thickness. the table saw was then adjusted to produce
    a 30 degree angle. Two more rip cuts were done to the leading edge
    of the aileron. Finished we had an aileron that anyone would appreciate
    taking out of a kit box let alone have scratch built. The laminating
    was done with simple CA glue. To say that these ailerons are stiff
    is an understatement.   I forgot to install two ply wing front dowl
    supports at the spare so a little surgery was in order. Two slots
    were cut and the pieces epoxied in place. I then install 1/8 inch
    pieces of stock to fill the slots cut. These were then sanded to
    a finished state. Repairs done this way yield a finish that doesn't
    need any other fillers. Sometimes when you try and put the same
    size sheeting back in place you tend to geta depression that then
    needs to be fixed. Next week I'll be installing the landing gear
    blocks and fiberglassing the wing center section.  I'm going to
    try a new method of holding down the fiberglass cloth while I apply
    the epoxy to it. I'll be using a spray contact cement to keep the
    cloth in place. Should be interesting. I suspect that the planes
    will be ready for covering in mid March. This will work good as
    by then most of the snow will hopefully be gone.
    
    
    					Regards
    
    						Tom
    
    
    P.S. Is anyone reading this?

    
    
    
    
    				YES!!
    

    
    
    
    				A-yup
    
    
    				Mike
    

Tom, are you sure about holding that glass cloth in place with
contact cement?  Seems like it would hinder the bond between the
resin and the wood underneath, and between the resin and the cloth.
Great idea, though.  How about using CYA to tack the cloth in place?
Or 5 min epoxy?

    
    	I have used CA to tack the cloth in the past. I got the 
    idea of using the contact cement from a CA tape. Hot Stuff
    I think. They used CA to bond the cloth to the balsa but 
    commented that they have in the past used epoxy for the 
    perminent bond. The contact cement is sprayed onto the cloth
    not the balsa center section. To my knowledge there is no
    penetration of the epoxy or resin into the glass fibers themselves.
    Rather the epoxy or resin penetrates the balsa fibers and
    surrounds the glass fibers to create the bond. The bond is 
    different from that of wood to wood where you get a penetration
    of the glue into the two adjacent materials. I don't see a
    problem if there is a surface of contact cement around the glass
    fibers. I guess theoretically that if you took a cross-section
    of the epoxy/contact cement/glass you may find that there is the
    possibility that the glass fibers could be floating inside the
    epoxy encasement on a film of contact cement. Would this matter?
    I doubt it. I know that float between to adjacent surfaces can
    cause problems. That is why most if not all pattern birds use
    epoxy to bond the sheeting to the foam. However I think that
    this theoritical floating of the fibers inside the epoxy would be
    minimal if at all present due to the make-up of the weave of the
    glass cloth.
    
    	These are my thoughts, any comments?
    
    
    						Tom

          		I usually use a drop of thin ZAP to hold the 
          cloth in place while I put the resin on..

The only thing that bothers me is that the value of a glassed
surface is the strength brought about by the union of the brittle,
but tough resin, and the strong (as in impact resistance), but
flexible cloth.  The value of the bond is proportional to the
wetting out of the cloth.  If you put something on the cloth to
prevent the resin from wetting it out, you are no longer
fiberglassing; in your case you are contact cementing!  

As I see it, your resin is worthless in this case; it is only
serving to glue the contact cement/cloth to the fuse.  Why not save
the weight and glue the whole thing together with the contact
cement? 

Remember the note we had in the old file about spraying the cloth
with nitrate dope before applying?  This was done to make the cloth
easier to handle and cut...could use the nitrate to tack the cloth
too, I suppose.  I think that works because the resin will disolve
the nitrate as it wets out the cloth.  Thats a happy marriage.