Re: hello again?

[Frank Pittelli <frank-at-pittelli.com>]

In Reply To Brian Kraack Who Wrote On  8 May:
> 
> any tricks or traps you know of (besides what's on the page already)?  What
> thickness sheeting did you use, and how did it stand up to paint hits ...
> What kind of batteries are you using?
> 

My Tiger was made as a skin-on-frame body, using 3/4" square plywood
for the frame and 1/4" luan plywood for the skin.  All the pieces were
glued together with good ole yellow wood glue and tacked into position
with brads.  After the body parts were all in place, the inside was
sealed with a thin coat of epoxy and the outside was covered with a
single piece of fiberglass cloth, leaving the rough finish.  This is
by far the fastest, cheapest and strongest building method.  Although I
originally used 1/4" luan, I will probably use 1/8" luan on the next
vehicle, because the fibreglass cloth adds a lot of strength.

The under-carriage is made out of alumimun stock and stainless steel
bolts, one assembly for each side, and then bolted under the hull. 
This allows the entire track assembly to be removed during various
phases of construction to work on things.  My original approach had the
various wheels attached directly to the hull and that simply didn't
work well.  If you make the track assembly as one piece, everything
becomes easier, both during construction and maintenance.

The biggest design decision concerns how to get into the hull to work
on the systems after everything is built.  My Tiger hull has a hinge in
the back that allows the upper hull (with turret and gun) to be swung
up like the hood of a car.  On the other hand, Will's tank hull pulls
straight up and comes off completely, because his hull shape isn't as
boxy as the Tiger.  Similarly, you want to be able to get into the
turret and work on things quickly so that battlefield repairs and
tweaks can be performed in a reasonable time.  Here again, the boxy
shape of the Tiger allows me to pop-off the entire top of the turret,
while in Will's Panther he pops off the entire turret.  That makes his
turret a little harder to get on and off, but he has easier access to
everything once it is off.

As far as durability goes, paintballs dissipate all of their energy on
impact and since they are relatively large to start with, they have
little effect on the wooden/fibreglass hull.  (We're not sure if the
same thing can be said for a plastic hull ... but we'll find out when
Will takes his Stuart out on the battlefield if the parts going flying.)

I use two 18Ah 12-volt batteries in the Tiger, which allows it to
operate at reasonable speeds for at least an hour.  The motors draw
between 5 and 10 amps while running.  We need to conduct some more
tests to determine the optimum tradeoff between weight and operating
time, but we're probably in the right ballpark.

        Frank P.