Modification - Long Big Bertha

Contributed by Frank Casey

Manufacturer: Modification
(Contributed - by Frank Casey - 10/17/07) (MODS) Estes Big Bertha

Brief:
This is a modified Big Bertha rocket. The main body tube was partially crushed when I purchased this kit. Estes sent a replacement which was also partially crushed. When the third tube came, I decided to couple it to the unharmed sections of the first two tubes. I also replaced the 18mm mount with a 24mm mount.

Construction:
Non-stock or replaced parts:

  • Used one stock BT-60 body tube and undamaged parts of two others
  • Replaced 18mm engine tube with 24mm engine tube
  • Replaced 18mm centering rings with 24mm centering rings
  • Replaced engine hook with one to accommodate D & E engines
  • Two coupling rings

Stock Parts:

  • Nose cone
  • Shock cord
  • Balsa fins
  • 18" parachute
  • Engine spacer (for use with D engines)
(MODS) Estes Big Bertha

The construction was straightforward. The only difference from building a standard Big Bertha is that I added tube length by coupling the undamaged sections of the first two body tubes to the one undamaged body tube.

Then I replaced the stock 18mm mount, rings, and engine hook with a 24mm setup to accommodate D and E engines.

Finishing:
At 41 inches long, there was a lot of Big Bertha to paint. I chose gloss black and the paint job came out great.

I am not a fan of the press and stick decals which this newer Big Bertha kit uses, but they went on fine and look great. The white decals really stand out against the gloss black paint.

Flight:
I wasn't sure how this would fly since I had changed the engine configuration and added length to the rocket.

I did figure that adding the length would cause the rocket to be fairly stable in flight and that turned out to be true. Actually the flight characteristics of the rocket have exceeded my expectations. This modified Big Bertha flies arrow straight and does it with great style without the addition of any nose weight.

It is now one of my favorite mods relative to flight!

Recovery:
I have flown this rocket four times on a D12-5. Recoveries have been excellent. The rocket gets right up there on a D12-5. I haven't tried it on an E yet, but I'd expect an almost out of sight flight.

Summary:
What started out as a major pain, that is receiving a rocket with a crushed tube and then receiving a crushed replacement tube from Estes, turned out to be a fun project. I'm actually glad now that the tubes were damaged because I wouldn't have modified the Big Bertha had it not happened.

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