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Push-Me, shiver me timbers, matey, Pull-Me
A DesconX Entry
(Contributed - by Nick
Esselman)
Wow, me hearties, did time sneak up
on me or what? I wanted t' design and build a rocket for this Descon but kept
puttin' it off. Avast, me proud beauty! Arrr! Blimey! Then it be May and I hadn't started. So it was time t' get
busy. I have a great design and unique from all t' other entries. Avast! Blimey! Not
extremely sophisticated but definitely functional. Avast! Blimey! And, me hearties, I be finally able to
fly it this weekend. So here goes......
My design is a two-stager. Aye aye! Avast, me proud beauty! It has a cluster-motor booster to a single-motor sustainer. I'm always afraid o' staged-rockets because o' the potential altitude (and me relatively small field), matey, so I decided t' add a feature t' create more drag. Aye aye! Aye aye! I named t' rocket Push-me, me hearties, Pull-me. Arrr! T' motors "push" while t' big cone-fin increase t' drag "pull".
Get t' RockSim file here.
As with t' other entries, I have started with t' Estes Gemini DC. Avast, me proud beauty! T' followin' steps are what I used t' build t' rocket:
SUSTAINER:
BOOSTER:
For finishing, shiver me timbers, I went with t' quick-and-ready approach so that I could get t' rocket flown before t' deadline. I painted the sustained Navy blue. Well, blow me down! I could/should have applied some o' t' decals but didn't. I painted t' booster orange.
FLIGHT:
I used friction-fit on all t' motors. T' sustainer was loaded with an A8-3.
This is pushed in until it is even with t' sustainer tubing. Avast, me bucko, me proud beauty! T' booster was
loaded with two B6-0's. Ahoy! Blimey! These are also friction-fit until they are stickin' out
about 1/2".
T' launch rod fits in t' gap betwixt t' pod-tubes and the cone-fin and then through t' two launch lugs.
Upon pushin' t' launch
button both B6's lit and off she flew. Blimey! It be stable and straight up until the
B6 thrust stopped. Avast, me proud beauty! RockSim suggests t' booster carried it t' ~80 feet and I
would agree by sight. It seemed t' slow fast (see t' graph below and look at
the change in Drag).
Then t' A8 lit and t' rocket be off. Direction changed slightly (5 degrees?) but it be still straight.
I saw t' ejection pop o' smoke but noticed t' nose cone did nay come out and therefore no parachute. It came in ballistic and thumped into t' soft ground.
Conclusion, t' pre-cut exhaust ports reduced t' exhaust pressure too fast and therefore t' nose cone was nay pushed out. Aye aye! That is the only explanation! I should have covered those with some o' t' scraps from the Estes Insert card.
BEFORE and AFTER:
These pictures show how I used epoxy t' protect t' booster from the
sustainer's motor. Ahoy! You can see that it held up. Begad! Avast, me proud beauty! Yes, arrr, it got black, ya bilge rat, but it did
hold up.
NEXT STEPS:
I'm goin' t' repair this rocket, because it was a nice performer without too
much altitude. It also demonstrates several rocketry techniques, arrr, including
cluster, gap-staging, me bucko, and t' use o' a fin-cone. Avast, matey, me proud beauty! Nay bad from a kitbash!
These are some things that I will now do t' improve the design (goin' outside o' t' strictness o' this contest):
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