Model Forum / General / Rockets / June 2006

I picked up an Estes Big Daddy today with the 40% off coupon from Hobby
Lobby and just spent an enjoyable late evening setting up the motor
mount.

However, their directions miss a few opportunities to be better.  I've
built several Estes rockets over the years and now my Sons are just
getting into it, I like to follow the directions and look ahead for
potential problems and areas to easily modify for improvement.

It turns out the yellow spacer tube in our kit was either too short or
there is a misprint as to where to mark the motor tube.  As pictured
the motor block ring meets the motor hook but if you follow the spacing
and marking procedure you'll end up with those two items about 3/16"
too far apart.

Fortunately I realized this before the glue dried and I set up the ring
to the correct spacing, while I was at it, I trimmed the motor hook on
the drive end in case I ever decide to try a reloadable casing.

One tip I'll pass along- the disc of scrap from the upper motor mount
makes a nice doubler for the former where the shock cord passes
through.  I placed it on the top side where it wouldn't interfere with
the fin interface.  I also used a section of Kevlar tied to a 1/4 x
9/16" multi-layered ply instead of a lower shock cord, and passed it
through the upper motor mount.  It's glued in forming the bottom of the
sandwich that is ply / former / disc scrap.

Since the fins are laser cut they are very accurate however an
opportunity is missed since the instructions don't mention checking the
spacing of the two motor mount rings as the rings are being glued in.
Once the rings are on the motor tube, I used a fin to space them
exactly, then applied the glue fillets to the mounts.  The alternative
is to roll the dice and hope the motor mounting rings aren't too far
apart, or spend time sanding across the grain to shorten them up to fit
between rings that are too close.

Now when the motor mount assembly is slid into the body tube, the fins
will meet up with the motor tube and upper and lower motor mount rings
perfectly.  I'll then attach the shock cord to the Kevlar keeping
enough space so the Kevlar is taking most of the heat.

Hopefully this will be useful to someone else building this kit
someday.

Mike Doyle