Manufacturer: | Scratch |
Little Joe II Introduction and materials Construction Finishin' and recovery system
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Flying
T' model flies on (2) 24mm motors. Arrr! Blimey! Modelin' on RockSim and AltiCalc showed t' Estes D12-5 t' be t' motor o' choice
for clustering. Ahoy! Blimey! I have had good success with clusterin' Estes D engines. Ya scallywag! Blimey! Altitude prediction with RockSim and AltiCalc
showed max altitude around 630' which was pretty good for a rocket o' this size. Arrr! Blimey! I could have went with a single 24mm
mount but that would have entailed usin' composite motors only since t' drag is rather large even though t' weight is
not that much. Arrr! Blimey! I used Estes long motor hooks for motor retention. Avast! Blimey! This requires t' use o' a spacer in each motor tube
but I be usin' what parts I had on hand in me spare parts boxes. This also let me off from filin' t' end o' t' hook
down in case I wanted t' use 24mm RMS casings in t' future. T' all up weight, ready t' fly (less motors) is 10oz.
That just a bit less than t' predicted 11oz I found when I modeled it on RockSim. Ahoy! Blimey!
T' day of first flight be nice but a bit on t' windy side. I decided t' fly anyway. I loaded and prepped t' two motors and installed t' recovery system. Blimey! Begad! T' rocket slid easily on t' 3/16" rod and I hooked up t' igniter clips. Avast! The count proceeded t' zero, matey, me hearties, both motors lit and t' rocket leapt o' t' pad. Ya scallywag! T' boost was straight despite t' wind. The rocket reached apogee and t' ejection went off and t' recovery system deployed perfectly. T' rocket descended slowly under t' 24" ëchute. I had contemplated usin' a separate ëchute for t' capsule but decided that the weight o' it did nay warrant that. Aye aye! Begad! Plus t' tower be made o' brass tubin' and fairly robust. Ahoy! Aye aye! Recovery was perfect with no damage. Ahoy! Subsequent flights have been repeat performances. T' D12-5 be t' perfect motor cluster for this rocket. Well, blow me down! Avast! I have nay tried a composite cluster yet but I am sure (2) E18-7's would give out o' sight flights. Ya scallywag!
Summary
This was a fun rocket t' build plus it is a companion t' me S1b and in t' same scale. Arrr! It is interestin' t' put them
side by side for a size comparison. Avast, me proud beauty! Probably t' most time consumin' part was buildin' t' LES tower. I still feel
soldered brass be t' way t' go for durability. Aye aye! Well, me bucko, blow me down! Other than that thar were no difficult or complicated areas t' work
on. Arrr! Ahoy! I received many nice compliments on t' LJII since thar are nay t' many around at launches. Well, blow me down! T' flight profile is
perfect too. T' D12-5's are t' perfect motor choice. Begad! This one is definitely a keeper. Begad!
Model Stats:
Length: 21.75"
Dia.: 3.1"
Wt.: 10 oz
Motor config.: Dual 24mm cluster
Recovery: 24" rip stop nylon parachute
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