Andy
Nope.. just remember the longer the better.. the rocket has to be at or around 50' per sec at the end of the rod to make a stable launch.
When in doubt make it longer (1/8" or 3/16" carbon fiber tubing 40" long works good for most aps.. if you are flying larger rockets I use a 6' rod (1/4") (Aluminum or SS).
IF.. the rocket was 2 feel long and had a 8” launch rod.. as long as the rocket makes 50fs at the end of the rod (LL in this case) you are golden.
Grim
sorry double post
Andy.. a D12 will put you at 52'per (930' alt) sec and a E9 at 42'per (1,519' alt).. if you can get that to a 5' rod you are looking at 55 per sec
on the E.. ..
I have flown rockets that slow off the pad just remember.. NO WIND or very light!
Grim
p.s. whats the body tube dia on that rocket?