> The number one problem I've seen with EZIs (and I've made this mistake!)
> is to keep pushing the airframe untill you reach the point of "ooh, it
> has a 54mm motor mount, what's the smallest reload I can put in that"
> at which point you drop in a J275, push it past mach and the fins fall
> off .... (I have heard of people who have built them with G10 fins and
> flown with J275s - but stock it's not going to work), it will fly on a
> J160 with a very long delay.
I watched my then 15 year old scare the daylights out of Ron Schultz at
LDRS XI by flying what Alex called an EZJ - 275. Ron's comment after
the very successful flight was " Kid, don't do that again." Ron and Deb then
very graciously autographed the air frame. Ron was not then aware hoe
much the mounts had been reinforced.
The bird was tracked to a little over 5,000 feet qith a +/- 0.05 error,
so it was a straight, true boost.
The rocket was assembled in a heavily modified and reinforced manner,
with 4 centering rings holding the motor tube, serious fillets on each cr
with the epoxy pumped in through small holes drilled in each segment,
them patched with small fiberglass patches.
The fins were very tightly mounted, with major glue fillets along the
fin / motor tube joints, the inside of the fin / body tube joint, and the
outside of the fin / body tube joint, with glass cloth reinforcement on
the outside joints.
The rocket had a weighted nose cone, with about a pound and a half of
bbs epoxied into it.
Later it was extensively used to loft 35 mm camera payloads, launching on
J 415s. Never lost a fin, but it was finally drowned in the swamp near the
Tripoli Puget Sound Launch site near Monroe, WA.
The EZI 65 is a good bird with a lot of useages. That 4 inch body tube is
a size that lends itself well to being used for serious active payloads
like cameras and other things.
You just have to beef up the fin mounts and use it judiciously with heavy
active payloads so that the big motors don't accellerate it beyond the
ability of the fins to withstand flutter.
Jim McLaughlin These opinions are mine, mine, mine!
And not anybody else's. So there.