Crayon 3E page 2
|Where was I ??
Oh yeah, we also need some motor blocks.
I like to use the ones from Andy of
Aerospace Specialty Products
(asp-rocketry.com) or from BMS. Or you
can cut up a used Estes 24mm motor
casing, its the same difference...
I set the blocks always to take 'E' motors,
and use spacers for 'D' size if I have to,
its always easier to adapt down. I went
really light on this bird using very little epoxy
only on the metal parts like screw eye,
retainer and rail buttons. Yes, rail buttons
from railbuttons.com (shameless plug !),
she ain't that heavy but bulky enough to
need them, and since I got that big ol'
'rail gun' of mine - no problemo...
lets move on...
...And cut up some fin slots. Since the 'wedge
mount' is ok, but not nearly as strong as the
'thru the wall' fin mount', I decided to add up
some considerable strength by slotting
the rear of the airframe for a partial 'semi ttw'
mount to compliment the wedge mounted fins...
Sharp hobby knife works really good in
cutting off the ribs on nose cone shoulder.
Sometimes you need to wrap it up with a
round of two of masking tape for a good fit,
sometimes gotta sand the inside of the tube
a bit, but this was perfect 'au naturel'...
A kevlar leader with a length of elastic got
tied up with three small 220lb quick links,
one in nose, one at the MMT's and one for the
chute... Chute is a ripstop nylon 36" LOC,
that I managed to shanghai some while ago...
Skip the elastic, go for kevlar all the way...
Just some blue and black Krylon paint on
the fins and MMT's, and ta-dah...
Here she is freshly finished...
...and barely a week later sitting on a rail
at NEFAR Bunnell Blast 2006. At the first
launch the shock cord got roasted thru...
And she took the expressway all the way
down from about 1100', thunking into dirt
fin first like a hungry graboid, but thanks to
solid construction she had no damage at all.
Here's a close-up, the rail buttons go thru
the airframe to a #8-32 nuts epoxied on
the inside of the tube and fully accessible
for maintenance or modification...
After that first flight I replaced the
whole shock cord assembly with
about 14 feet of tubular kevlar,
reloaded her up on E9-6's and
cut her loose the second time.
That time the chute got half
tangled up in a 'parawad'
recovery mode and she came
down fast and loose in a tail slide.
After scaring most of the spectator
gallery she again thunked down
hard, this time in tall grass and loose
dirt. Again, no damage...
One tough little bird !