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Contributed by Darren Wright (Contributed - by Darren Wright)  Brief:
Estes' re-release of the upscale Big Bertha.
Modifications:
Converted to fly on dual-24mm motors and changed the upper body-tube into a
payload section.
Construction:
The kit includes:
- Two (2) standard Estes BT-80 tubes
- Four (4) upscale Big Bertha 3/16" Balsa Fins
- A 24mm mount
- Paper centering rings
- A NC-80 nose cone
- An Estes 18" parachute
- An Estes standard chute mount
I built the kit without directions, but Estes has always done a great job
with their directions. I wanted to include a payload section, and while I was
rummaging around for an extra BT-80 section, I came across some dual 24mm
mounts for BT-80 tubing. (And a big GRIN came over my face!) I figured with the
payload plus an altimeter, the dual would be needed (Yeah right!)
I built the kit using West Systems epoxy with Silica filler throughout,
really slopping it on near the motor mounts. Since I was butt mounting the
fins, I use the old epoxy rivet trick. I punched holes with a pin along the fin
lines, and squish the fins on there, forcing epoxy into the holes and making
"rivets". I have long since invested in an Estes fin holder, so the
alignment is quite good. This kit is about as strong as an Estes kit can be. I
expect it to fly fine on dual E15's or E30's.
Finishing:
I have not finished it yet, but it will follow suit with all other Estes
products.
 Flight:
The recommended motor is a D12-5. I doubled up and use two D12-5's. Both
ignited, and the flight was nominal. Both motors were successfully held in by
the dual hooks.
I then used two E11-5J's What a great flight! Nice and slow with a lot of
smoke! Chute protection is via wadding. No problems encountered there.
Recovery:
The 'chute is now too small, and the rocket comes down too fast. But I like it
that way, and the rocket can handle it. I'd rather break a fin, than loose the
whole rocket. But with the epoxy construction, the rocket was fine.
Summary:
I'm really glad Estes has re-released some of the old-timers. It's typical
Estes, but great for nostalgia. Flight Log- Post a Comment -
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