My 'Crypt Keeper' Is 8" X 9' 6"... One Center 54mm and Two 38mm. I will be using a center K660 and the outers will be J285. All CTI.
Ive been reading and found this basic rule of thumb for newton/weight ratio at pad loaded.
"Take pad weight and multiply by 25 and make that your minimum liftoff Newtons of thrust"
Does this sound about right? Of course given many veriables in rocket construction and size,this would only be an est.
My rocket will weigh 23lbs at most (loaded). 23 X 25 = 575. My Minimum Ns. My K660 is a little over four times that. Should leave pretty well.
All this is to decide when to light the two J285. At pad or hold or off a few seconds.
thanks MikeS
PS. Also found "NAR safety in that it states max weight should not exceed 1/3 of the impulse"
I think this is for low power...?
Throw it into Rocksim or OpenRocket and check velocity off the rail. Also very handy for figuring out timing for airstarts.
-Ken
Did that this morning: Just with the K on OpenRocket. 13.9 ms (31.9 mph) aprox alt 3700ft.
Assuming most was filled out correctly 🙂
Seems pretty reasonable??
Latest Post: Hello World Our newest member: ted41b90301689 Recent Posts Unread Posts
