Experi-MENTAL

Hi, my name is Geoff Marshall. I have been a BAR for about 2 years and am currently the president of the British Columbia Rocketry Club. I am also a member of the Canadian Association of Rocketry and hold a CAR level 3 certification. I hope you enjoy this presentation of my Descon 9 entry.

The idea for this rocket came after flying the new Estes E9's for the first time this past September. I liked the long burn time and the gobs of smoke and they perform great in small, light rockets.

The conversation leading up to this design sort of went like this.

Me: I like the new E9's
Other Guy: Yeah, but not much good for bigger models.
Me: True, but you could do a nice cluster.
Other Guy: Or boost it with a D12.
Me: Or a cluster of D12's!
Other Guy: Hmmmmmmmm!
Me: Hmmmmmmmmmmmmm!!!

Thus Experi-MENTAL was born!

• I wanted a relatively big model, 2" X 36" or so
• At least a 2-stage design..... maybe 3-stage
• Initial booster stage would be a cluster
• Sustainer would fly on an E9

Here's a screen capture of the final design

(Click for larger image)

PARTS & CONSTRUCTION

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I chose LOC/PRECISION components for construction as I feel they offer the 'best bang for the buck'.

Parts List:

Airframe:	LOC 2.56" - 1@16.5" sustainer and 2@ 5" boosters
Nose Cone:	LOC 2.56" plastic
Motor Mounts:	LOC .95" - 2@4" booster1, 1@4" booster2 and 1@4" sustainer
Couplers:	LOC 2.56" - 2" for each booster
Centering Rings:	Homemade from .050" kraft paper card stock - 2 per stage
Fins:	3/32" balsa laminated with printer paper & epoxy - 3 per stage
Recovery:	8' of 1/2" tubular nylon & homemade 18" ripstop nylon chute
Guidance:	Acme Conformal rail guides
Misc:	Industrial Formulators 30 min. epoxy used throughout construction

 

Below are some pictures taken during construction
(Click on the small images to view full size)

Airframe completed boosters & motor mounts under construction	All 3 stages complete with motor mounts installed	Completed & ready for paint
The business end of stages  recovery system installed	Staging & recovery layout	Paint, decals & rail guides applied
Another shot of the finished bird	Jared demonstrates how to insert a rocket into little brother Seth's nose

FLIGHT REPORT

Experi-MENTAL had her maiden flight at the British Columbia Rocketry Club's model and HPR launch held in Pemberton Meadows B.C. on Nov. 18th 2001. The sky was clear and the temperature was hovering around 0°C (32°F).
Experi-MENTAL was loaded onto a 6' 80/20 rail with 2 X D12-0 in booster1, 1 X D12-0 in booster2 and a E9-6 in the sustainer. At ignition both motors in booster1 lit up together and the rocket came off the rail nice and straight . About 150' up booster2 lit and the rocket snapped over at about a 45° angle :-( She continued to arc over down range and, you guessed it, the E9-6 in the sustainer lit up right on cue. So now we have the sustainer headed for the ground about 3/4 of a mile down range powered by a motor with a 3 second burn time, needless to say I gave up any hope of the rocket surviving. We did see a puff of smoke from the ejection charge but at that distance you couldn't really tell if it was before or after impact. We then proceeded to launch the rest of that rack and I ended up making a trek into the surrounding woods to help retrieve someone's L2 bird. On returning, another club member offered to help me trek out across the muddy, semi frozen potato field to retrieve what was left of Experi-MENTAL. We found booster 1 just 100 yards or so down range with one fin hanging loose at the fillet. I looked up to get a line of site to booster 2 and the remains of the sustainer and notice another club member heading towards me waving his arms and yelling something. On meeting up with him I discovered not only had he recovered the intact booster 2 but the also completely intact SUSTAINER!! It appears that the ejection charge fired just high enough above ground to get the laundry out and save the bird.... no zippers, no dings, not even a scratch! Experi-MENTAL will fly again!

Post flight analysis:

Close inspection of the stages revealed a scorch mark down the inside of booster1's coupler. It appears that the 2 motors in booster1 burned through at slightly different times and caused the stage to jam at an angle until the ignition of booster2 kicked it off. This is what caused the sharp change in trajectory and sent the rocket on it's long downrange arc.

The fix:

For her next flight I am going to shorten the coupler on booster1 from it's current exposed length of 1 1/8" down to about 3/4" and sand it to a slightly looser fit. Hopefully this will allow the booster to eject cleanly even if the tandem motors pop at different times. Booster2 will remain unchanged as it appeared to perform as planned.

Overall I am very happy with how this rocket turned out and plan on flying it again in various different configurations, booster1 and sustainer only, booster2 and sustainer only and just the sustainer as a single stage rocket. If Estes does release the E9-0 I will definitely fly her on a full load... 2 X E9-0 to E9-0 to E9-8..... Good-bye!!