I've explained this many, many times on r.m.r. (a Google search of r.m.r. is a very fast way to find info without having to wade through the stink).
Here is a summary:
Build it stock. Do not add extra weight (extra weight comes from replacing the lightweight parachutes with heavy nylon parachutes, filling the fins with epoxy or wood, using epoxy to assemble the motor mount, too much paint, etc.).
With the E9-4 it should weight between 1 pound and 1.1 pounds.
Launch in ZERO wind. Us a 1/4" diameter x 6' long steel launch rod and use the entire rod. Some folks try using a Mantis pad and that is a disaster because the mantis swallows a huge amount of the rod AND it does the "Mantis Dance" when the motor ignites and the rocket starts to move.
Photos of our club members launching with E9-4 motors are all over the lower portion of the jimz photo gallery web page. They fly great when you follow my advice above.
If you launch in wind, with an overweight model or using a short launch rod, your model will barely have any airspeed as it leaves the rod, the rod may bend at a dangerous angle and the rocket will possibly arc over and impact.
The D12-3 gives a slightly faster lift-off, but it will not provide as much total impulse as the E9-4. The D12-3 is better if there is a slight breeze and you need the slightly lighter lift-off weight and faster rod departure speed. you just won't fly as high.
And you can always use the Aerotech F21-4. It will kick your V-2 off the rod FAST and it will go much too high.
Originally posted by SpartaChris
My V-2 loves to veer one direction or another right off the launch pad. I was wondering if any of you other Estes V-2 owners have had a similar experience and what you possibly did to correct it? Could it be that it is under powered? An E-9 seems barely enough to get the thing up in the air. Could I have put the motor mount in crooked? Could it be out of balance?
Thanks in advance for your help.
-Chris