Here's some ramblings for ya!
Today I got to fire off a few A & B motors......I chickened out on the C6's after the last flight ended up in the tree.....Off to the sports field for that....I ain't building this a third time... The rocket was a re-designed 18mm LM...ie.LM # 2
Big blue sky, 25.5degC. No clouds at all...
Launch # 1 A8-3...Maiden test flight.. Good as usual! No altimeter. Rocksim predicted altitude - 101ft - 76ft/sec. Recovered 30ft from pad. Video shows violent deployment / separation.
Launch # 2 B4-4...A bit better...Launched with Alt15K. Rocksim predicted altitude - 231ft - 110ft/sec. Altimeter reading - 209ft
8.77% below predicted altitude. Recovered 75ft from pad.
Launch # 3 B6-4...A great little engine...perfect for the launch site. Launched with Alt15K. Rocksim predicted altitude - 251ft - 123ft/sec. Altimeter reading -
268ft
6.77% higher than predicted altitude. Recovered 150-200ft from pad. Almost in the tree!!!
Launch # 4 B6-4...Launched with Alt15K Rocksim predicted altitude - 251ft - 123ft/sec. Altimeter reading - 252ft
0.4% higher than predicted altitude. Recovered 10ft from pad. Best flight of the day.
Notes : The three small NC screws, whilst only weighing 0.3g each, have a large effect on the altitude reached. The button head is about 3mm Dia. and 1.25mm high. The drag created from them is enough to reduce the altitude by 100ft on a C6 motor.
And here's some more silly numbers. Spent motor weights from my last 2 launches.....
(A8-3) - 10.9g / 10.7g / 10.8g / 10.5g Ave - 10.725g (B4-4) - 10.7g (B6-4) - 10.8g / 10.9g Ave - 10.85g (C6-0) - 9.3g (C6-7) - 10.4g