[simpits-tech] A-4 website updated again

[LT1_Z28]

Sean Galbraith wrote:
> 
> Easier than that... he's got the forward fuse, seat and canopy off a busted
> DG200 (IIRC) which will be the donor for the project.  I think his plan is
> to make it portable and cart it round to airshows and the like as an
> interactive recruiting tool for the sport.

Hell, he's set! Hmm... how about a pod molded into the top of the
fuselage just behind the canopy to house a projector?
 
> Best part about the A-4 canopy is that there is a heap of meat in the lower
> section of the frame (look at any photo...) so I could even bury some
> aluminium longerons in there.

Forgot to mention one little thing. Make absolutely, positively sure
that you either zinc chromate the hell out of the aluminum, inside and
out, or use anodized aluminum. If you don't you won't have any longerons
in about a year ;) Well, a little longer than that, but they will
definately go away due to galvanic reactions and stuff.
 
> I could build a box frame to mount the pivot and glass that into the back,
> and maybe connect it to the longerons.......  this is getting better.

That's the way to do it. Build the structure then bond it in. Done right
it'll last until the day after forever. Just make sure you get some UV
blocking paint on it. UV + epoxy = bad things.
 
> Well it will be nowhere near flat so it should be as strong as houses!

I got bored a while back and pulled an 1/8" thick hemisphere made of
polyester resin and medium e-glass mat off a beach ball. It held 265
pounds 3 hours after layup with less than 1/4" deformation. The next day
it didn't deflect at all. I used that as a mold to make 2 more parts,
trimmed 'em, and bonded the two together with an internal flange (not a
particularly easy flange to make). Dribbled it down the driveway like a
basketball, making a really odd sound, and punted it over the house. The
damn thing just wouldn't break. I finally wound up painting it like a
giant eyeball for halloween and, of course, some little punk stole it.

So, yes, glass is strong ;)
 
> Do you know of any online tutorials on glass stuff?  Really need to learn
> more now :)   All I've ever done with glass is some crash repair on various
> bikes.... (and even some carbon on my 400RR!)

There are a few at the various composite supply shops' sites, but if you
need anything specific feel free to ask. I've done a few things to my
bikes, too. Like a full fairing and solo tail for a Ninja, made from
scratch ;) Also, carbon is best used to make things look pretty or add
stiffness, not strength. The only realistic way to add any strength in
excess of what you can get with glass is to use either prepreg or rigid
laminates. Carbon is very picky about fiber orientation. I just got a
book called Composite Basics by... I can't remember the author. It's
mainly intended for homebuilt planes, but has a lot of good stuff on
structure design and testing. Took me about 20 minutes to design the
spars for my ultralight (28' span, 9" deep front spar, 4" deep aft spar,
white pine caps, urethane foam and glass webs, right at 30 pounds).
It'll take some special fixtures to build it since the urethane foam is
cast between the caps, but it won't be too tough... at least the
construction won't be. The spar itself, however, will be damn near
indestructable ;)
-- 
Steve
lt1_z28@swbell.net http://www.mysticz28.org/
Jesus saves, Budda enlightens, Cthulhu thinks you'll make a nice
sandwich.