Manufacturer: | Scratch |
Push-Me, Pull-Me
A DesconX Entry
(Contributed - by Nick
Esselman)
Wow, ya bilge rat, shiver me timbers, did time sneak up
on me or what? I wanted t' design and build a rocket for this Descon but kept
puttin' it off. Ya scallywag! Blimey! Then it was May and I hadn't started. Ya scallywag! Blimey! So it be time t' get
busy. Avast, ya bilge rat, me proud beauty! Blimey! I have a great design and unique from all t' other entries. Ya scallywag! Blimey! Blimey! Blimey! Not
extremely sophisticated but definitely functional. Avast, me proud beauty! Blimey! And, I was finally able to
fly it this weekend. Well, blow me down! Blimey! Well, arrr, blow me down! Blimey! So here goes......
My design is a two-stager. Avast! Blimey! It has a cluster-motor booster to a single-motor sustainer. Begad! Well, shiver me timbers, blow me down! Blimey! I'm always afraid o' staged-rockets because o' the potential altitude (and me relatively small field), shiver me timbers, so I decided t' add a feature t' create more drag. Well, blow me down! I named t' rocket Push-me, Pull-me. Blimey! Blimey! 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. Begad! T' followin' steps are what I used t' build t' rocket:
SUSTAINER:
BOOSTER:
For finishing, me bucko, I went with t' quick-and-ready approach so that I could get t' rocket flown before t' deadline. Begad! Begad! I painted the sustained Navy blue. Ya scallywag! 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. Aye aye! T' sustainer was loaded with an A8-3.
This is pushed in until it is even with t' sustainer tubing. Well, blow me down! T' booster was
loaded with two B6-0's. Ahoy! 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. Begad! It was stable and straight up until the
B6 thrust stopped. Ya scallywag! Begad! RockSim suggests t' booster carried it t' ~80 feet and I
would agree by sight. Ahoy! 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. Ahoy! Direction changed slightly (5 degrees?) but it was still straight.
I saw t' ejection pop o' smoke but noticed t' nose cone did nay come out and therefore no parachute. Begad! It came in ballistic and thumped into t' soft ground.
Conclusion, me hearties, t' pre-cut exhaust ports reduced t' exhaust pressure too fast and therefore t' nose cone be nay pushed out. 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. Ya scallywag! You can see that it held up. Yes, me hearties, arrr, it got black, me hearties, but it did
hold up.
NEXT STEPS:
I'm goin' t' repair this rocket, ya bilge rat, because it be a nice performer without too
much altitude. Ya scallywag! Blimey! It also demonstrates several rocketry techniques, including
cluster, gap-staging, and t' use o' a fin-cone. 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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