I should have asked, have you put the weght in to correct the CofG, or is
the CofG now well forward of the specification?
Check the CofG, if its forward of the spec then your overstable which is not
a major problem so long as your aware of the wathercocking potential.
If you had to add excessive weight to move the CoG to the correct place then
you need to check you have plenty of power to lift it - thrust greather than
5 times weight is the general rule of thumb.
I have a few different nose cones that are interchangeable, all with
different nose weights epoxyed in.
Here is the the Stovis last flight profile, loaded with 6 Estes E9's
and a core motor of a AeroTech 24mm reload of a F.
The rocket left the pad, then flipped end over end into the dirt of
Maddox Dairy farm. What went wrong here?
Did all of the motors light? Mixing APCP and BP motors is not a
recommended clustering method. The BP motors tend to ignite before the
APCP motor. In fact almost all of the time the APCP motor will not
ignite at all because the ignitor is pulled out of the motor when the
rocket starts to move under the thrust of the BP motors.
So assuming that all 6 of the E motors lit but the F did not you would
have a launch profile of only a 162 N/S H54. That would be marginal
with a Stovi with an extra 6oz. of weight in the nose cone. I'd
suggest that the low initial thrust did not get the rocket moving fast
enough to fully stabilize itself before it left the rod/rail. If so a
slight gust of wind would be all that was necessary to destablize the
rocket resulting in the flight that you describe.
If the rocket yaws more than about 15 degrees for any reason (like not
all engines lit) or if the wind is enough to give a yaw angle of more
than 15 degrees as the rocket leaves the pad (this happens when the
lift off speed is too low) then the fins will be stalled and will not
produce the corrective force needed. The end over end tumble is what
usually happens in that situation.
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