Diameter: 1.64 inches
Length: 24.00 inches
Manufacturer: Estes
Skill Level: 1
Style: Sport
(by Paul Gray) 

Background

The Big Bertha is a classic rocket built and flown by thousands of people around the world since 1965. Its was designed to have a rather impressive size and to develop the skills of people who are advancing themselves further in the hobby of model rocketry. Because of its size and performance, it is a great rocket to fly on a football field on C motors, and it is perfect for beginners of model rocketry and demonstration flights. 

Construction

[Rocket Pic]The rocket overall is rather simple to build although it requires proper fin alignment, finishing, and proper building techniques. As said before, building this rocket will give the beginning rocketeer a good introduction into using these skills. There are things to watch for when building this rocket. First of all, like many rockets, the motor mount centering rings can angle when you glue them onto the motor tube. Not only should you make sure that they are straight when you first glue them on, but keep any eye on them. They can angle by themselves as the glue dries. Second, the motor hook is held with masking tape that is wrapped around the motor tube. Tape will work just fine. Just make sure that the hook runs straight down the motor tube and use plenty of tape. Third, its very common for plastic nose cones to have flash leftover from the manufacturing process. Be sure to trip any flash off of the nose cone with a hobby knife. Finally, its very important to make sure that the launch lug is glued in between two fins. The rocket is only good for pitching into the trash can when it is in line with a fin, because of course, you can't load the rocket onto the launch pad. 

There is a method of gluing the motor mount into the rocket that I used on this rocket. Its a method that I learned building high impulse rockets. I put the motor mount into the body tube without yet getting out the glue. Then I used a ruler to line the back end of the motor tube with the back end of the body tube. I then put a glue fillet around inside where the back centering ring meets the body tube. I then stood the body tube on its front end and let the glue dry completely before doing anything else. Then I took a long balsa stick and through the front end of the tube, I reached the stick down and spread glue inside around where the front centering ring meets the body tube. This method works very well in gluing the motor mount in strongly. 

When gluing on the fins, make sure that you have good marks drawn on the tube. Preglue the fins before gluing them onto the body tube. Pregluing creates a stronger joint between the fins and the body tube and also helps to have a nice flat root edge for gluing. These are the steps to the pregluing process:

1.Put a thin coat of glue on the root edge (edge that glues onto the body tube) of the fin.
2.Wipe off any excess glue off from the coat you just put on the root edge of the fin. You don't need much glue for this. All you need is a thin, flat film of glue.
3.Let it dry before gluing onto the body tube.

And last, be sure that you glue the fins around the rear end of the body tube. I nearly made the mistake of gluing a fin to the front end of the tube. Not good.

Finishing this rocket isn't anything too complex. Its all black, so you won't need to worry about being an artist. I am using Krylon black paint, and before I paint the rocket, I spray Krylon sandable primer on it, and sand it smooth. This really improves the finish. Krylon clear coat really adds to the finish too after the decals are added on.

Flight

One reason this rocket is a classic is because of its unique look and performance. It flies best on C motors. It likes all of the power you can give it. Its design allows it to fly perfectly straight up. Many people also like the way it floats back down on its 45 centimeter parachute. It doesn't wobble or fall too fast. It comes down slow and majestically. 

Grades

Design: A+ 
Construction: A 
Flight: A+ 

Flights

Comments:

avatar
K.R.J. (November 1, 2000)
The Big Bertha was the first "big" rocket I ever built. I got one when I was 12 and in the hospital. The nurses all thought I was crazy for building a model rocket in a hospital bed, but it went together well. ( I didn't paint it there, though!) Years later, after moving to Europe, my friend Ernst bought me one for Christmas. He couldn't believe that I had one as a kid! This is absolutely the best kit Estes (or Robbe GmbH) ever put out. Period. [As far as the review] Exactly the same experiences. Had to chase mine a half mile once because of the large parachute.
avatar
J.W.P. (January 1, 2001)
Big Bertha is the favorite in our fleet. We have never had a bad launch. Specifically, the large tube size let the chute pack loosely and it opens well. Also, this model tends to weathercock. This means it tends to angle into the wind on its own. The harder it blows the more it flies into the wind and is more likely to land back in the launch field.
avatar
D.T.H. (January 1, 2001)
This kit is quick and easy to assemble. I have been flying my kit for about 6 years. It takes a lot of abuse and keeps on flying. A great first kit for kids. I always take it with me to fly.
avatar
P.D.M. (May 1, 2001)
This is a great, classic rocket with good size (for an Estes kit). I built it with a 24mm (D&E-size)engine mount and I added epoxied BBs in the nose to offset the additional weight. I also replaced the cheap Estes chute with a Rogue 18" nylon chute with a spill hole cut out. I then painted mine a combination of black and turquoise to set it apart from the rest of my rockets. I first launched it with a D12 and it flew great! Straight and high. Then I tried an Aerotech E15 and it was spectacular! My last flight of the day was with another E15 and another great flight, but the winds took it almost out of sight and an hours search was fruitless... it was gone. A great kit and I highly recommend the 24mm engine mount, but get ready to get on your horse for recovery.
avatar
D.P. (July 1, 2001)
My Big Bertha has flown 32 times on everything from an A8-3(low flight)to a D21-4T(great flight) as of 6/27. It now has very thick epoxy fillets on the fins because of them coming off and gluing them back on. I switched out the 18" chute after 28 flights because of excessive drift for a 14" one. The review was right on. The reviewer did not think the drift was bad, but it became a problem for me. Otherwise, I would rate the Big Bertha at a 4.5 out of 5.
avatar
D.H. (October 2, 2001)
I've had my Big Bertha for just under a year now and have launched it probably twenty times. Visually, I don't find it all that impressive, but it sure is reliable. In fact, just the other day, I had to launch it with no recovery system at all. I had forgotten that I removed the parachute, but it flew great. Four great flights and only one tiny tear in the body tube.(fixed on site of course!). I always launch the Bertha first on launch day, to test the winds, because I know I will get it back. Long Live Bertha!
avatar
M.B.H (October 11, 2001)
The Big Bertha is probably my favorite rocket. It's robust, reliable, and has great flights. I launched it one day four times, compared to one or two for my Rattle-7. I flew it on an A8-3, for a low, short flight, B4, B6, and a C6 drag race with another Bertha on an Aerotech RMS D. A sweet rocket that I personally do not think I could ever do without again, now to get a couple more to add to my inventory...
avatar
M.C.L (December 26, 2001)
I flew a 1969 model that was the original and had been stored in a box in a garage for 30 years. It has the balsa nose cone and fins. The things to look out for when building this model are the fins. If you use balsa (I recommend retrofitting the newer Estes model with balsa fins), glue them on with Epoxy. I also used epoxy on the motor mount and the shock cord mount. It ended up as an all-epoxy model. The added weight did not affect the C.G appreciably. I added a heavy duty snap swivel and 1/4" elastic shock cord from a fabric store. I sealed the nose cone and fins with Elmers fill-n-finish and sanded each with 400-grit for a perfect finish. I finished mine with OSH spray paint in purple, red and yellow. I made a custom decal (since the original model had no decals, unlike today) for mine. I did the design in color using Adobe Photoshop. I then printed that at Kinko's on their color laser printer but I had them print it on what they called "sticky back" which is a clear, adhesive-backed film. I cut out the design (leaving a 1/8" margin) and stuck that to my model. Final cost? About 2 bucks. Looks awesome. The model is then clear-coated for a mirror finish. I modified this big Bertha with a homemade 24" ripstop nylon X-form parachute. It is heavier than the Estes plastic one that comes with the model but it is built like a tank (to match the rocket). Estes hit a home run with this model. It has flown countless times and has never given a bad performance. It flies straight and true and recovers perfectly each time. I fly it on C6-5's due to the extra weight and it performs flawlessly. This is a great model for an intermediate beginner and will never cease to impress your friends. I recommend not using the black paint job and, instead, coming up with your own design for this odd-looking bird. The crowds love it and it will fly and fly again.
avatar
B.A. (March 24, 2002)
I luv my Big Bertha. The only troubles I've had is that after about 10 flights the engine mount began to come loose. I think I'll use it as an experiment platform. I love how it goes up nice and straight and has a graceful landing.
avatar
J.R. (July 30, 2002)
My only quam with building this rocket came from the motor mounts and the shock cord system. For the motor mount before it's installed make eight small balsa triangles (gussets) with the scrap balsa that is leftover from the fins. Make them small enough so you can glue them every 90 degrees around the forward mount (these would be in the aft position) and the rear motor mount (these would be placed forward of the aft rings). Also replace the shock cord with a Kevlar® cord that could wrap around engine and threaded through the forward ring then attach sewing elastic (found in fabric stores) just after the Kevlar® cord exits the body tube. I used Fill n Sand for sealing the fins and used a wet finger to make real smooth fillets which I then sanded with 220 then 400 grit for a nice finish. Primer, sand ,primer, sand (600grit) tack cloth then paint two coats of color followed by three coats of clear...AWESOME!
avatar
D.W. (April 5, 2003)
You just need to look at the amount of entries in the flight logs for this rocket, and count the number of times words like 'perfect' and 'great' are used to show what a class rocket the Big Bertha is. Its not the highest flyer; but the slow, realistic take off, and the lovely slow arcs to apogee makes up for that!

comment Post a Comment