Rocketry Update

Although several rocket launches here in Alberta have been cancelled recently, I have continued to build new rockets. Why? There are a variety of advanced construction methods being used today and I want to learn them. Each rocket that I build is designed to include one new fabrication technique that I have not used previously. I hope that by doing it this way, only “one thing” can go wrong at a time.

What have I learned so far? The Estes Crossfire was my first modern model rocket. The instructions were very clear and the rocket was very well designed. It allowed me to build and fly a model rocket, forgiving any minor mistakes that I might have made. My goal was to recover a rocket by parachute, something that didn’t happen back in the “good old days” of amateur rocketry. The Crossfire was fired three times, with a perfect parachute recovery each time.

The Rocketarium VK-7 was next. A little larger, it used a cluster of two motors and also employed a baffle to help protect the parachute from the burning ejection gases. The instructions were not quite as specific as the Crossfire’s, but I built and flew the rocket without problems. Both of the motors ignited on time and the parachute recovery was perfect.

Both of the preceding rockets used “through the body” fin attachment, which gives greater strength. Now I wanted to see what happens when you glue the fins directly to the body tube. I built the Hebe, which flew three times. Because it was little more than a motor with fins, it attained higher acceleration and velocity figures than any rocket I’ll likely build in the near future. Happily, the fins did not get ripped off during flight or broken on landing.

So far, I had been using 18mm motors. I built the Ceres B to gain experience with a 24mm motor. The test flight was perfect, but the rocket drifted away on the wind and was not recovered. Lesson learned: if it is somewhat windy, try a smaller parachute.

Romulus

Those are the only rocket I have flown to date, but I’ve been busy in the workshop. The Romulus is a 2-stage rocket that uses 18mm motors. I mentioned it before in “Learn to Build Rockets” and showed photos of the unusual fin assembly. It is ready to go.

Ceres B2

The Ceres B2 is similar to the Ceres B, but uses a 3D-printed fin can and baffle. It also is ready to go. I will be taking some smaller parachutes with me, just in case…

The Eris II also uses a 24mm motor, a 3D-printed fin can and baffle. It is a smaller-diameter rocket than the Ceres and VK-7, and should reach an altitude of about 1800 feet. Yup, it is ready to go as well.

Eris II

Lastly, I am building my first rocket to use a 29mm motor. I am using plywood centering rings and fins, instead of balsawood, and using epoxy glue instead of wood glue. The fins are attached to the motor mount in “fin-can” style just like the Romulus booster, and just like the recommended method for the Aerotech Mega-Initiator, which my wife gave me for my birthday. My original goal here was to learn how to glue up plywood parts with epoxy glue. I just finished attaching the fins, and should have the rocket ready to test by November, although I will try for October.

I am also happy to report that the ERC has assigned me a very experienced mentor from among their ranks, who will guide me along the path to high performance rocketry. He believes that the rocket I am now building will be suitable for my L1 Certification flight. HPR flights cannot be done in Calmar, so my first chance would be in February 2023 at the ERC’s annual Fire & Ice launch.

The Mega-Initiator is a 4″ diameter rocket that can take motors of 29mm, 38mm or 54 mm and requires lots of HPR know-how to built it right. That’s why I have been learning these skills on smaller rockets, and why I have been assigned a mentor. With a bit of luck, this rocket might be ready to fly at Fire & Ice, too, provided I don’t spill epoxy all over my feet and get bonded to the garage floor!

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3d-Printed Rocket Buzzer

Rocket Buzzer

At the last rocket launching I attended, several of my rockets greatly exceeded expectations and were likely swallowed up by the universe at large. Two things might have helped: a smaller parachute and/or a tracking device.

This tracking device is based on a design by Adam Nehr, published in the March/April 2022 issue of Sport Rocketry. Mr. Nehr’s excellent article is nine pages long, so you should probably read it for complete instructions on how to use this tracker.

My design does not require soldering or messing around with epoxy, nor do you need to buy and then modify the battery holder. The red part is 3d-printed in PLA and only takes about ten minutes on my Dremel 3D20.

https://www.thingiverse.com/thing:5452251

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Learn to Build Rockets

Estes Designer’s Special and Make: Rockets

Today’s model rockets aren’t anything like the amateur rockets that we “old-timers” built back in the 1960s. How was I going to learn to make rockets today, and where would I get all of the parts needed? My solution was to buy a copy of “Make: Rockets” and an Estes “Designer’s Special” kit of assorted model rocket parts.

The book shows you how to make about a dozen model rockets, including rocket-gliders, using parts from the “Designer’s Special”. Everything is explained so it is easy to understand, and there are lots of photos. The construction techniques are basic, but solid. So far, I have built and flown two rockets from this book — the Hebe and the Ceres-B, both of which I have described in previous posts.

Currently, I am working on the two-stage Romulus (second from the left, on the book’s cover). The book says it will fly to about 1500 feet, but with my modifications to it OpenRocket (a free rocket analysis program) limits it to a more conservative altitude of just over 1000 feet. Ok by me, maybe I won’t have to walk as far to recover it.

What modifications, you ask? In this book, the author glues the fins directly to the body tube. This method is outdated, since it dates way, way back to when the book was published in 2014. Rocket kits today attach the fins through slits in the body tube, so part of the fin glues directly to the motor mount inside. The Estes Crossfire and Rocketarium VK-7 both did it this way. I am doing this on the second stage (sustainer) of the rocket. Larger rockets, such as the AeroTech Mega-Initiator, suggest gluing the fins directly to the motor mount, then slitting the body tube up from the bottom so that you can just lower it down on top of the motor mount/fin assembly. I am doing this on the first stage (booster) of the Romulus, so that I will have some experience with this method in case somebody gives me a Mega-Initiator for my birthday in a few months.

There are a lot of interesting designs in this book, and I still have a lot of parts left over, but once the Romulus is finished my immediate plan is to experiment with some electronic payloads and attach a miniature video cam to the larger rockets, at least until my birthday.

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Up, Up and Away!

L to R: VK-7, Ceres-B, Crossfire, Hebe

The Edmonton Rocketry Club was back in Calmar on July 30. So was I, with four rockets ready to go! The Crossfire from Estes had already flown three times previously, and was included as a spare. The scratchbuilt Hebe had previously flown twice, suffering water-damage on that second landing. I transplanted part of another rocket into the mid-section to attempt one more flight. The VK-7 from Rocketarium and the scratchbuilt Ceres-B were ready for their first flights.

Hebe Flies Again !

Hebe was the first rocket launched that day. It was powered by a “C” motor this time, and launched with a vengeance. The projected altitude was 1231 feet, but it went so fast and was so small, that I never saw it again!

A great success, but also my first offering to the rocket gods…

Next up was the VK-7, my first rocket to use a cluster of two “C” motors. The trick is to get them both to ignite at the same time, or else things can go awry very quickly.

The crowd was warned that this was a “heads up” launch, meaning be ready to dive for cover! To my great relief, the motors ignited perfectly and the VK-7 rose majestically into the sky, easily reaching the projected altitude of 633 feet (over 1000 feet, IMHO) and making a perfect landing.

All of my previous model rockets flew on motors that were 18-mm in diameter. The Ceres-B was my first experience with a 24-mm motor, in this case a “D”. It easily reached its projected altitude of 1017 feet, had a perfect parachute deployment, but caught the wind and was last seen drifting south. I searched for about an hour but never found it. My fault — I should have used a smaller parachute, but instead … my second offering to the rocket gods!

Before you start feeling sorry for me, let me just say this was my best rocket launching ever! In 1964, I was a student member of the Rocket Research Institute and launched an amateur rocket to an altitude of about 1000 feet. We didn’t use parachutes back then, so we didn’t recover our rockets either. My immediate goal as a “born-again rocketeer” was to break the 1000 foot altitude, and this time around at least two (maybe three) of my rockets did that. Yes, it was a perfect day!

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AARM-50+2

On July 17, the Edmonton Rocketry Club hosted a rocketry competition in nearby Calmar, Alberta. People launched a variety of model rockets, competing in various categories, with varying success. The only thing that wasn’t variable, was the excitement! I didn’t fly anything, but had fun trying to video some of the launches.

Read more about the competition on the ERC website: https://www.edmontonrocketry.net/aarm-50

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