Boris and Paul's Aeronautics
and Space Administration

Paul's TARC team ranks 17th in the 2015 finals out of 700 teams in the USA!


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Built from the Polecat Aerospace Fat Man kit - a 2x upscale of Estes Fat Boy
Modified for dual deploy and 19x 24mm motor cluster flight
27 inches tall by 5.5 inches diameter, flight weight 8 pounds.  Click on any picture to enlarge

Videos:   2010 flight videos   playlist of several HellBoy videos     More info:   2011 flights   2012 flights   Rocketry Forum thread

please see links above for later flights

flight 2:   11/21/10   CMASS   Amesbury, MA

1x Pro-X F30 White (AP)  + 18x D11-P (BP) motors

Impulse: 1x 73 Ns + 18x 18 Ns = 397 Ns total

Thrust: 1x 30 N + 18x 11 N = 228 N

19 motors = I-228

The flight went very well, firing all 19 motors and reaching 863 ft.

BP motors were fired by a QM flashpan. Used one Rocketflite ML igniter for the AP motor and another for the flashpan. Flashpan was also exposed to AP motor exhaust to have two ignition sources. Used a small cotton string beneath 3 BP motors to prevent rocket creeping up the rail before the BP motors were pushing hard.

In the first flight the rocket took 0.5 seconds from first visible sign of ignition until it started moving up the rail. In this flight the time was reduced to 0.4 seconds, likely due to the addition of the fast hitting ProX motor.
Times were determined by counting video frames in 720 60p video.

Slight wiggle during boost suggested the need for slightly more nose weight with this engine combination. Flight was in very low winds.

Main chute was slow to unfurl, so I'll pack it to deploy more quickly next time. That's me trying to talk the chute into opening up in the video.

Once again, the rocket is in great shape and will fly again next spring. Maybe with the addition of some cool flame graphics...

first flight:    11/6/10    CMASS    Amesbury, MA

19x D11-P Estes motors. 19 x 18ns = 342 Ns total.
Equivalent to a Black Powder I-209 with a strong initial thrust spike.
Created a flashpan using QM and BP contained between double layers of masking tape flat against the bottoms of the motors.

Confirmed CG is at 16", which Polecat instructions state is as far back as it should be.

photo by Bill Spadafora                              
The Hell Boy flew for the first time in light winds just before 2pm on 11/6/10.

All 19 D11-P motors fired creating enough heat to produce a long central flame trail plus the characteristic BP white smoke and hissing sound.
A very pleasing effect.

Liftoff was straight and recovery went perfectly. Altimeter reported 716 ft.

Build - Fall 2010     Click on any picture to enlarge

The Polecat Aerospace 5.5" Fat Man kit comes with a fiberglass nose cone, pre-glassed body tube (looks like LOC 5.5"), beveled 1/4" fins, 2 centering rings, 54mm engine tube, plus some other hardware and instructions. Flier supplies chute. A good deal at $99.

As a 2x upscale of the classic Estes Fat Boy, it has a wide body ideal for clusters.

Plan is to use low cost 24mm motors, 19x of these fit well in a 5.5" airframe.

Used a jig from BMI to align fins. For this mod glued a 6" coupler tube at the bottom of the body tube. Trimmed the tabs on the TTW fins. Then epoxied them into the slots in the body tube, butting them up against the coupler tube.

Generous fillets with thick, fast Locktite 5 minute epoxy. Then glassed very lightly using thin 1.3oz FG layers. Three layers where fins join body, one layer everywhere else. West 206 epoxy. Just enough to help anchor the fins and provide a hard, smooth surface to the exterior.

After plenty of sanding, applied a topcoat of epoxy and then sanded that down.

Cut LOC 24mm tubing into 18 pieces 5.5" long and one 6" long for the center. The center tube contacts the solid bulkhead, other tubes are shorter to avoid interference with bottom parts of recovery hardware. Glued tubes into a honeycomb using yellow, quick-tacking Elmers.

Cut strips from a "stiffy" tube at 6 contact points, these plus the top of the center motor tube hold the motor honeycomb into the rocket.

Painted West 206 epoxy on the outside of the motor honeycomb and inside of the space they mount into, to bond and fire-harden.

Rocket body (no NC) went from 2.0lbs to 2.5lbs with addition of motor tubes.

Painted inside of the recovery area with thinned epoxy for fire resistance (West 206 + 25% alcohol by weight). 38mm internal tube for altimeter and 3" internal tube for main chute.

The altimeter sled with PerfectFlite HA45K altimeter, Duracell 9V battery and Featherweight screw switch (other side). There is a wooden block below the battery, the tape only has to retain its sidewards motion inside a tight fitting tube. Deployment ground tests confirm 1.5g BP for main and 1.5g for drogue.

Added 7x threaded rods for retention, 3" long 8-32, with 3/4" exposed. Also painted the inside of the motor tubes with thinned epoxy for physical and fire hardening.

Rocket is 6.1 lbs flight ready minus motors, will be 7.9 lbs with 19x D11-Ps. A BP "I" impulse flight.

Will likely reach 700-800 ft, so dual deploy is not really necessary but I like having a second recovery event and chute for insurance. Also facilitates higher impulse options in the future.

Paul holding the Hell Boy. Mounted rail buttons on 1/4" thick basswood risers, both to prevent rail from scraping rocket and to give the rail button screws more to bite into. Rail buttons are just loose enough to rotate freely, for reduced friction and better longevity.

For main wrapped a 45" chute and short Kevlar harness in an 18" square Nomex sheet and packed that into the internal 3" tube. For flight will put one long strip of masking tape over this after the ejection charge is inserted. Top Flight Recovery parts.

Drogue is 24" CATO chute on Kevlar harness. Shortened harness and added nylon section after first flight.