The SillyCopter
(Contributed - by Bob Fortune)
I've enjoyed building and flying variations of the Estes Gyroc and Jonathan's
Cyclone (Maple Seed Rocket) so much I decided to try a variant of my own.
The Gyroc pops an engine to deploy its flaps then spins to the ground. You
can see a plan of this rocket at JimZ's place.
The Cyclone pops its booster and the upper body tube twirls to the ground in
a like a maple seed. This rocket can be seen at:
http://www.cs.indiana.edu/hyplan/jwmills/EDUCATION.NOTEBOOK/rocket/rocket.html
There is another Estes rocket (the Tornado I think) that also uses a
tumble-recovered booster and spinning upper BT in which one fin stays on the
upper body tube whose name I can't recall similar in nature to the Maple Seed
Rocket. Both the Cyclone and Tornado have solid mounted single fins that impart
spin upon descent. You might be able to find this at Jimz's place also.
The SillyCopter recovers in a somewhat similar yet boingy manner. At apogee
the upper BT and booster separate and the sustainer tips over as the springy
pulls the fin and holds it in an attitude like a flap or foil for a
spinning descent. The booster tumbles to the ground in a disorderly manner like
the first stage of a multistage rocket.
So you get to keep your eyes open for both rocket parts!
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This rocket flies very well on A through C engines. It will need some tweaking
of the music wire fin holders once it is assembled and additional tweaking
after a couple of flights to get the sustainer to spin properly. Fly it on an
Estes A8-3 or Quest A6-4 for the first flight. A C motor puts it up there
pretty far, about 1000', and makes recovering the booster a challenge. For
the upper portion to spin nicely the key is to imagine the foil of a helicopter
blade and bend the wire accordingly.
The design of the wire-to-fin junction is relatively robust but take care
that you grasp the fin sled and wire firmly when bending to get the foil just
right. Also take care that the coupler slides freely from the body tube on
deployment and that the "fin sled" is waxed occasionally with
paraffin to make sure it releases cleanly. This is very important! Also take
care that the "sled dog" tabs don't snap off when the "fin
sled" is inserted into place. Grasp the fin and upper body tube in one
hand and guide the fin into the booster sled dog. A couple of flights, a bit of
adjustment and the thing will spin nicely. Prep is easy because there is no
parachute or wadding.
Installation of the black vinyl tape to hold the music wire tight to the
body tube is simple and location is not critical as long as it is on the lower
portion of the upper body tube. Two wraps of tape spaced a couple of inches
apart is all that is necessary. You might also try leaving it off completely
but the fin really bounces around as it moves through the air.
You might also try building it per alternate #1. This is a bit more work but
it's interesting to see. Put some talc in this compartment and it will poof out
when it impacts the ground.
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Parts List:
* 2 or 3 BT-50 couplers
* 2 BT50 to BT20 centering rings
* 1 BT20 thrust ring
* 1 BT50 nose cone
* 10" 20 or 22 gauge music wire and wire cutters
* 3" BT20 as motor mount tube
* a couple of balsa bulkheads, cut and fit as you go
* a sheet of 3/32" balsa
* epoxy, 5 or 15 minute
* 3.25" BT50 for booster BT
* 4.25" BT50 for lower section of upper body tube
* 11.5" BT50 for upper section of upper body tube (so you need 18"
overall)
* launch lug - mounted 6" from aft end of complete rocket
* yellow glue or white glue, some CA and might also be handy
* black vinyl electricians' tape
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| If you build this and fly it please let me know! : ) If
you need help with its construction please feel free to email me. Have
Fun! Bob
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