Conference vmszoo::rc

    Well I have started on the fuse of the Spirit 100 and I am making good
    progress.  I intend to build the bolt on wings, however one thing does
    not seem quite right.  There is quite a gap between the the bolt plate
    in the wing and the bolt blocks in the fuse.  In my opinion, it would
    be better to have the two block plates touch, or at have a solid wood
    connection between to transfer any forces on the wing into the fuse and
    vice versa.  
    
    Is it normal to have a gap between the bolt plates, and if so why?  It
    should be quite easy to build upo some wood so that there is a solid
    contact between them.  Is there any reason why I should not do this?

    On a hard landing you want the nylon bolt to shear first before any
    structural damage. The space between the plates allows this to happen
    more easily, especially with the larger bolt sizes, >10-32.
    Another common failure point is right at the base of the bolt head.
    This point is more likely to fail on the smaller bolt sizes, and in
    fact is where the Chuperosa bolt always fails. The Chup has no spacing
    between the bottom of the wing and the lower bolt block. 
    
    Ideally you should have only one bolt, in order to allow a pivoting
    action, with the trailing edge located by a small easily broken dowel
    or even a piece of tape across the top. The Chup uses the latter, and
    I've never broken a wing or mount structure.
    
    Terry

Hmmmm. I guess I've got a different opinion on how the wing should be bolted
down. I personally prefer the wing to be as rigidly attached to the fuse
as possible so that it's always in proper alignment and it flies right. OK,
I suppose it becomes less tolerable of bad landings, but I don't like the idea
that the wing can shift whenever it's subjected to stress. I remember flying
Al Ryder's Chup, with just a single bolt holding the wing in place (no dowel
or tape to prevent pivoting), and the wing was actually shifting as a result
of the hand toss. 

Nope, I'd rather build strength into the fuse at the attach points of the 
wing, then concentrate on learning to land nice and smooth. As for the space
under the wing where the bolt comes thru, I would think that there would be
bending stress on the wing that might cause a crack there? I guess I'd feel
more comfortable with a wood to wood contact, allowing the bolt to be tightened
down without stressing the trailing edge.

    
    In some ways I think the rigid setup might break the bolt easier
    (meaning better). It will shear off instead of stretch and maybe spring
    back. And it won't pull up on the plate when it trys to break.
    It will just shear off quickly and cleanly. Maybe?
    

    One way to use the single bolt and still provide a positive attachment
    is to install a small 1/8" dowl downward through the wing and app. 1/4" 
    into the bolt block. This will lock the wing in from side to side and
    still shear off in the event of a bad crash.  I've seen this used on
    pattern ships with the pins on the front and back. Then they installed
    one bolt in the front and one in the back. On a pattern ship bolting at 
    the front and back is used to allow adjustment and to eliminate the
    problems with using dowls in the LE.  Most time they wear.
    
    
    Tom

    Although my opinion of NSP has been colored by recent experiences
    that a club member has had when discussing his Alcyone with them
    (the only source for that kit, BTW), that is neither here nor there
    and Sal is entitled to his opinion of the Spirit, which will not
    affect its popularity, I predict.
    
    Getting back to wing mountings, when using a bolt on wing it's
    a good idea to use rubber strips of some sort along the top of the
    fuselage edges in the wing saddle area. Regular foam self-stick wing
    seating tape is ok for fiberglass fuselages but for balsa I've
    found that a strip of ordinary ~3/16" rubber band, CA'ed on, works
    best.
    I've used this on the Chup and have none of the wing swiveling problems
    mentioned by Dave.
    
    When using nylon bolts on the trailing edge, they should be as small as
    possible. Two small ones can be better than one larger. 6-32 should
    be plenty large, I've used two 4-40s on 100" wings with no problems.
    
    Terry

    I've used 2 4-40 nylon bolts on my 2 meter all season and the only
    bolts I broke were ones my son overtightened (hey dad, they just keep
    turning and turning 8^)

    I use carbon graphite rod as a guide for the bolts.  They prevent
    crushing the trailing edge when you tighten the bolts down.  I have
    always made sure that there is no space between fuselage and 
    trailing edge when using the bolt on method.  The friction is what
    provides the grip.
    
    Will