I picked up this model last year at a hobby shop here in town ("Aero-Tronics Model Supply Co.") where I used to buy plenty of Centuri kits "back in the day" (read "1970's") to contribute the fin patterns to Ye Olde Rocket Plans (YORP), only to discover the patterns were already printed in the instruction sheet posted at JimZ.
I found it odd that this BT-55 kit had a mini-engine mount with a 9" long stuffer tube, and I thought it was an awfully heavy rocket for 13mm engines. So today I finally got my money's worth out of RockSim
and worked up the attached files below.
My suspicions were confirmed with "wimpy" 13mm engines, so I just upgraded this kit to an 18mm mount (which I will probably end up using). However, in the spirit of Bill Eichelberger, who seems to have a hankering for engines labled D, E, and up
-- I couldn't seem to leave well enough alone, and did a 24mm version, as well.
Here are the general numbers for those of us who don't have RockSim:
Motor -- Max. Alt. (feet) -- Deployment (feet) -- Speed (feet per second)
13mm
A3-4T -- 176 -- 143 -- 41
A10-3T -- 170 -- 165 -- 18
18mm
A8-3 -- 153 -- 150 -- 15
B4-4 -- 365 -- 363 -- 11
B6-4 -- 371 -- 370 -- 6
C6-5 -- 794 -- 791 -- 13
24mm
C11-5 -- 706 -- 705 -- 4
D12-5 -- 1254 -- 1250 -- 21
Cheers,
--Jay
(who discovered the main body tubes for his "Thunder-Awk" and pre-release Semroc "Aphelion" clone were crushed in the post-flood... "rearranging")