Hummm...deciding between bolt-on or rubberbanded wings is getting tougher all the time.
What do you think of the following feedback I received from
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- I like your idea of matching the wing saddle [with a contoured plywood strengthener on the sides of the fuselage], it will be much stronger, and won't add too much weight.
- I would use 3/32" light ply [for the strengthener]
- I would use 3/16" dowel for a small plane like that, and let it protrude
1/2 - 5/8"
- This is ok as is [the fact that my swept wings are not flush with the leading and trailing edges of the saddle but have gaps fore and aft], but if you want to close it up [the gaps], you could lay waxed paper over the fuse bottom, then mount the wing, and fill both areas with some of that Super Light Spackle. let dry, and sand to shape.
5 definitely strengthen the rubber band area. I would suggest wrapping the TE with some aluminum cut from a soda can. ==
BOLT-ON WINGS PROS AND CONS
- Looks much nicer than rubber bands + dowels.
- Less risk of crushing EPP on LE and TE.
- Getting wing alignment right is more difficult; once block is in place and holes are drilled, I'm pretty much locked in.
- If the wings shear off completely during a cartwheel, I risk having the servo lead wires ripped apart unless I fabricate some kind of teather to keep the wings close to the fuselage (similar to ski straps).
- If the hardwood block should split (or if the bolt should break in the block) I'm hosed.
- The hardwood block would have to go near the CG, which is right where I'd want to put a ballast area.
RUBBERBANDED WINGS PROS AND CONS
- Looks like crap, not at all to scale.
- LE and TE where rubberbands intersect have to be strengthened, either with hardwood or aluminum can cutouts (or both).
- Cutting out a plywood saddle contour is non-trivial, but adjusting wing alignment and incidence is easy.
- Like bolt-on wings, this configuration also needs a teather. One could easily be attached to a graphite or carbon fiber rod used in place of a wooden dowel.
- Rubberbands will probably break before the plywood saddle contours break.
- The fuselage area surrounding the CG will be empty, so I can cut out a nice ballast area.
Gosh, now that I've enumerated all these issues, maybe I should ditch both ideas and just glue the darn wings on! This will certainly be lighter AND a lot less work...
>
> >The problem with bolt-on wings is that nylon bolts are designed to shear
> >when placed under stress, I expect to be "stressing" my foamie glider A LOT!
> >If the bolts shear on account of rough landings, I'm afraid that I'll be
> >spending half my time in the field replacing them.
> >
> >Also, if the wood blocks in the fuselage should spit I'll be in big trouble
> >as "fixing" this would require major surgery on a foamie wrapped with
> >fiberglass packing tape. So for these reasons, a rubberbanded connector is
> >the way to go.
> >
> >(By the way, about 3 weeks ago I posed a similar question, but at the time I
> >was actually considering using a bolt-on wing. Half the replies I received
> >were of the form: "Why don't you consider using rubberbands and dowels
> >instead?" Now that I've made the switch, respondents are asking the
> >opposite question: "Why not use nylon bolts instead?". It never fails...)
> >
>
> Good Points Ken,
>
> What you need to do is to design the bolt-on system right! Use ONE
> bolt, a 1/4"-20, through the wing at the CG and into the EPP fuselage,
> and have the hardwood block (Maple block) about 1" deep. What I would
> do is just pass an Xacto carving blade through the 2" EPP side and
> slide the block in place. Use a second (shear bolt) near the trailing
> edge, going into the balsa at the wing and into the EPP of the
> fuselage. That bolt can be as small as a 6-32. This bolt screws only
> into the wing and slides into the EPP fuselage. This bolt is mainly an
> alignment pin which pops out of the fuselage when the plane is hit, or
> if you catch a wing-tip during landing.
>
> The EPP between the main bolt and the Maple block will give a lot of
> shock absorbing action when the wing is hit. The 1/4" bolt will shear
> only in a direct hit, which would pop off rubber-bands anyway.
> Glancing hits and wing-snags would only pivot the wing. You just pivot
> it back and you're back into action.
>
> I hate rubber bands. When the plane gets hit, the rubber bands tear
> into the wing trailing edge. Using enough rubber bands to keep the
> wings from shifting crushes the EPP soft foam.
>
> -Fritz
>
>
>