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

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+ 

Background:

This spring I ran a build session for faculty kids at the school where I teach. I ended up using the Quest Bright Hawk for the 7-9 year olds and the Quest Big Betty for the 10-12 year olds. After the build session, I began thinking about the types of rockets that would make great first builds for a budding rocketeer. I wanted to select rockets to compare that had the following in common:

• BT-60 body tube
• Parachute recovery
• Balsa fins
• Engine hook motor retention
• Reasonable Price
• Stable flight performance
• A rocket that can fly on small athletic fields and can be viewed in all aspects of flight. In other words, no Alphas, Wizards, or Vikings.

I ended up selecting 3 rockets that fit these criteria. The Estes Big Bertha, the Quest Big Betty, and the Fliskits Rhino.

Click Here for the Comparison Article.

Construction:

The Big Bertha is your standard Estes Skill Level 1 bird. The instructions are adequate, and the parts are usually average to above average in quality except for the shock cord (too short). The motor mount is easy to construct, and the engine hook is simple to add to the motor mount. What is nice about the Big Bertha is the length of the motor mount. This reduces the overall amount of the body tube that needs to be pressurized at deployment time. It also makes it easier for clumsy hands to handle. The fins are die cut and require minimal sanding to get a good finish. Remember, I tried to build the Big Bertha as a beginner would. Using the double glue method, it is easy to get the fins on the body tube. I added fillets to the fins and added the very long launch lug to the body tube. As is the case with many Estes kits, the parachutes may arrive already with shroud lines attached. All I needed to do was add the shock cord using the tri-fold method, attach the parachute and attach the shock cord to the nose cone.

Finishing:

Finishing consisted of priming and Fill-N-Finish. I then painted my Big Bertha with a 60’s design. Had I finished the rocket as a skill level one bird, I would simply have given it a solid coating of black and put on the one simple self-stick decal sheet. Since this was the Big Bertha, a classic, I did give myself the liberty of designing it my way, rather than the simple black.

Construction Rating: 4 out of 5

Flight:

I have flown my Big Bertha on B6-4s, C6-5s and even a D21-7. This bird always turns in a solid performance flight after flight. It is very easy to prep and pack the parachute. With the size of the rocket and the big swept back fins, the Big Bertha can be a great demonstration model to be enjoyed in all stages of flight and recovery. This is probably one of the reasons why it is a classic.

Flight Rating: 5 out of 5

Overall Rating: 4 ½ out of 5

Brief:
Everybody's favorite prom date, the Estes Big Bertha, is a rocket that seems to wind up in every fleet at one time or another. While there are a lot of other rockets in her size range that equal her low, slow, and always stable flights, there's something to be said for building and flying the original. Bertha's getting a little long in the tooth these days and in need of an update, but it's nothing that a quick shot of Kevlar couldn't fix.

Construction:
The kit contains:

• BT-60 main body tube
• BT-20B engine tube
• PNC-60L nose cone
• 2 RA-2060 centering rings
• engine hook
• elastic shock cord
• balsa fin stock
• 18" parachute

The Bertha instructions remain the standard by which other skill level one kits are written. (I'd prefer that the part numbers were still included as a part of the exploded view, but that's a personal nit that I felt the need to pick.) The Bertha has no "gotchas" and is the perfect starter rocket for those with a taste for small field flying. I attached the engine mount with Elmer's Wood Glue and for the first time in a long time, glued in a stock Estes shock cord with a tri-fold paper mount. Normally I would use about six feet of combined Kevlar® and sewing elastic, but I wanted this comparison to be about stock models built the way the instructions said. So for the sake of the comparison, I went retro.

My fin attachment method did have a nod to the new millennium. I tacked the fins in place using LocTite Gel CA, then filleted them in place with two heavy lines of wood glue per joint.

Finishing:
Although the Big Bertha paint scheme I modeled was the 1969 catalog version, the finishing remained the same. Before anything was done I coated the spirals with thinned Elmer's Fill 'n' Finish, then sanded the whole thing smooth. The fins, which were shaped as was directed in the instructions, were then given two coats of the same Fill 'n' Finish with sanding between each coat. The rocket was given a base coat of white, then masked to allow the 1969 catalog scheme to come to life in black and red paint. I used Valspar paints throughout the project with the final touch being an Estes logo decal that JimZ sent me with an order back in 2001. Why go to this much trouble? Because the current Bertha paint and decal scheme is DULL! If ever there was a rocket ripe for updating, the Big Bertha is it.

Construction Rating: 4 out of 5

Flight:
While this wasn't my first Big Bertha, I wanted to fly the same progression of motors that I flew in the other three rockets in this comparison: a B4-2, B6-4, and C6-5. All three flights were made on a windy day which I knew from experience would make for some long recovery walks, so I started with the C6-5 flights while my legs were fresh. The Bertha on the C6-5 climbed to a pretty respectable height, then drifted downrange 1/4 of a mile or so. The stretch of field we flew on that day has exactly one rocket eating tree on it, and for a moment it looked as if the Bertha might land in it, but a fortuitous gust carried it past the tree and to the left. I was able to cheat a little and do most of my walking on the access road, which cut down my time between flights and made my legs feel less like lead from stomping through the weeds.

The B6-4, while noticeably lower than the C6-5 flight, would still allow you decent small field flights with very little fear of losing the rocket to a tree. The Bertha recovered about 100 yards from the pad and I was back prepping for the third flight very quickly. Flight #3 was on a B4-2, which was suggested to me as a way to get a good liftoff picture. I still managed to get the rocket smoking on the rod, but the flight was interesting in that it took a moment for the rocket to find it's way after clearing the rod. It looked as if it stopped for a moment before kinking noticeably to the right as the wind caught the big fins. Recovery on the B4-2 flight was just past the pad, but windcocking was pretty severe. (Not always a bad thing.)

Recovery:
Recovery was handled by the stock 18" Estes chute, heavily reefed to cut down on the aforementioned recovery walk. That didn't matter though. I walked myself to death anyway. This hobby needs caddies.

Flight Rating: 4 out of 5

Summary:
PROs: Classic styling, variety of catalog paint schemes to choose from, and foolproof design and instructions.

CONs: Not enough shock cord! And would it kill Estes to come into the 21st century and start including Kevlar® as part of the recovery system?

Overall Rating: 4 out of 5