Model Rocket Plans

The Cyclone is a BT-20 medium-sized model rocket that uses a
"unicopter" recovery system based on the dynamics of a maple
seed. These plans are derived from the final version of the
rocket, which has been extensively flight tested. The model is
easy to fly and works reliably. As usual, you should be careful
whenever you launch any rocket.

A BT-5 version was also built, but is harder to see and easy to
lose due to its small size. Therefore only the plans for the
easy-to-see and easy-to-find BT-20 version are listed. Still,
the BT-20 version can take up to 20 seconds to descend in light
winds.  Launch it on a very windy day and you could lose it.

Be especially careful to follow the directions exactly when
you build Cyclone. The weight distribution, the spin unit's fin
angle,and its structure are critical for correct unicopter
operation. The design is also interesting because the spin and
stabilizing units are stable when connected together, but highly
unstable individually. The instability in each is what causes
them to spin, each in a different way, to the ground, without
the need for extra fins or canted fins (as in the Estes® 
Tornado and Estes® Twister).

Therefore, making changes to this design can result in flights
that are hazardous to the builder and spectators. Undertake design
modifications and subsequent flight testing very cautiously.

The rocket is composed of two units. The parts list and
assembly instructions are given for each:

After building each unit, paint or decorate it according to
your preference. This painting scheme emphasizes the flat
rotation of the spin unit (painted BT-5 Mini-Cyclone shown).


Assembling the Cyclone for Launch is accomplished by inserting
an A3-4T mini-engine into the stabilizer unit. The two units are
then joined by attaching the stabilizer unit's coupler to the
spin unit (BT-20 Cyclone shown).

Attach an igniter and a launch plug to the mini-engine, then
place the rocket on the launch rod. Make sure your launch
controller is safed, then attach the mini-clips. Insert the
key into the controller, give a 5-4-3-2-1-Launch! countdown,
and send Cyclone up! You will hear the rocket whistle during
its ascent (due to the exhaust gas vent), then at apogee it
willl separate into the spin and stabilizer units. The
stabilizer unit will fall back quickly, while the spin unit
will take up to 20 seconds to return, appearing to hover in
the sky.

You might add chrome tape to the spin unit and see if anybody
reports seeing a flashing UFO!

Continue to The Spin Unit
Back to... Return to Designing a Maple Seed Rocket
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