After a hiatus (you know, it’s 2020…), we’re back with The Model Rocket Show!
This episode is a classic “workshop” episode fans of The Rocketry Show have come to enjoy – and the N00b is joined by Jesse and Gheem from The Rocketry Show! CG is there, too, but just listening quietly in the background (you know how Gheem and the N00b can ramble on…)
In the first half of the show, we answer listener questions, including one from a Patreon patron which slipped through the N00b’s email for a while (sorry about that, Les!).
After our break, we get to talking shop with a fun, longwinded conversation which culminates in… MURDER!!!
…of the N00b’s Mercury Redstone escape tower.
A lot of rocketeers have been frustrated by a build over the decades, and sometimes smashing a piece which is getting your goat feels like the only solution…
In this episode, we chat with James Duffy, an accomplished scale modeler and competitor in FAI international model rocketry competitions.
James’ main specialties in scale modeling are the Bumper WAC – an early American two-stage sounding rocket consisting of a captured German V-2 first stage with a WAC Corporal cobbled on top as a second stage…
…and the Little Joe test vehicle, which NASA used during Project Mercury to test the launch escape system (the Little Joe II was later used for the same purposes for Project Apollo) and heat shield.
One impressive model James has flown in international competitions is his 1/12 scale Little Joe.
We discuss scale modeling and get his advice, and James tells us about FAI international model rocketry competitions. The American team has made a bid to hold the World Championships here in the United States in 2023. This would be the first time the international fly-offs will have been held in the U.S. since 1992.
Also, check out Spacemonkey Models (CLICK HERE), James’ company selling the most detailed scale model V-2 available anywhere. It’s a static model (which means it doesn’t fly), but it can be converted to a flying model rocket with a conversion kit sold by Apogee Components (CLICK HERE to get it). You can also buy the Spacemonkey V-2 itself from Apogee.
I have one of the Spacemonkey kits, and it’s a gorgeous thing. James has a thorough video tutorial series for building the V-2 on his YouTube channel. CLICK HERE to go to the playlist.
The kit comes with four different decal sets, so you have what you need to build one of four different iterations of the V-2, and the decals fit almost perfectly to the Estes V-2, so with a Spacemonkey kit you have the decals to build three more flying models!
In this episode, we talk with Gary Rosenfield, who founded AeroTech Consumer Aerospace in 1982. AeroTech makes ammonium perchlorate composite propellant motors, often referred to as simply “composite motors.” This distinguishes them from the traditional model rocket motors, which use black powder propellant.
AeroTech is known for making high power motors, up to the enormous M, N, and O impulse motors. But they also make low and mid power motors for model rocketeers.
Around 2014, AeroTech merged with Quest Aerospace, a model rocket company which manufactured kits and black powder motors. The motors were rather similar to the Estes black powder motors, but included the much-loved Q2G2 igniters.
Q2G2’s were fast igniters. That is, they required less amperage to fire, and with a small black pyrogen tip, they were great for igniting black powder clusters – configurations of two or more motors.
With clusters, it’s important to have all motors ignite simultaneously, or the rocket could leave the pad with one or more motors unlit. This can sometimes result in a less-than-straight flight trajectory, and it’s what makes clustering a fun challenge!
Following an accident in a port in China, through which Quest’s old motors were exported to the U.S., Quest motors and igniters became unavailable for a long time.
Bill Stine, who had founded Quest, challenged Gary to create an A-impulse motor with composite propellant.
Gary accepted the challenge, and after a long period of development and experimentation, the new Quest composite motors became a reality.
Dubbed “Q-Jets,” these little 18mm motors are the same length and diameter as standard A/B/C model rocket motors, but because they contain the more energetic AP composite propellant, Quest/AeroTech can get a D powered motor into the smaller sized casing.
This is because AP propellant has a higher specific impulse than black powder propellant.
Q-Jets are fast, fun, zippy motors. And AeroTech has lots of different AP motors for rockets of all sizes.
You can get Q-Jet’s from our sponsor, eRockets.biz, by clicking here.
In this episode the Rocket N00b answers some model rocketry questions – some beginner’s questions commonly asked on online forums, as well as a couple questions sent to him through social media.
“What’s the Best Glue?”
Yes, we know. This question gets asked a LOT online, and some rocketeers get tired of seeing it. But it’s a good sign – it means there are new people entering the hobby all the time. That’s good for us, as it means more people to support our vendors of kits and motors, as well as greater awareness of this safe and awesome hobby.
The long answer is on the show (the N00b does tend to ramble). The short answer: for most model rocketry applications, you want to use white or yellow glue. Brand is pretty unimportant – pick one you like. The bond formed between paper and wood with these glues is stronger than the materials themselves. If a fin breaks off, it’s not the glue that failed – it’s probably that the body tube’s paper has ripped off, or a fin has snapped at the root.
Here’s a video sent to the N00b by Kirk G. showing a strength test of various white and yellow glues.
Obviously the construction technique here is quite different from what you’d be doing when building a model rocket, but it does illustrate the point that these glues are plenty strong.
Here’s the link to the Titebond page showing the differences between Titebond I, II, and III.
And here’s a quick video from Titebond comparing the three glues.
We also talk about epoxy, CA or super glue, plastic cement, glue sticks, and finally, hot glue (DO NOT USE HOT GLUE).
The plastic cement the N00b mentioned (but couldn’t remember the name) was Plastruct Plastic Weld.
The rockets the N00b mentioned during our sponsor segment – eRockets.biz – were by New Way. You can look at all the New Way kits eRockets carries by clicking here.
“Do Engines/Motors Go Bad?”
A lot of times, people will have rocket motors from a decade ago or more. Many people on the forums ask if they’ll still be good.
The fact is that model rocket motors, whether they are black powder or composite motors, do not have an expiration date. The important thing is how they’re stored. If they’ve gone through a lot of hot and cold temperature cycles over the years, the propellant grains can crack, making them more prone to catastrophic motor failures, or CATOs.
But people have flown 30-40 year old motors with no problems.
Some composite propellants, such as White Lightning or White Thunder propellants, can have some surface oxidation on them, making them harder to light, but that’s about it. Again, temp cycling may be a problem, but if properly stored, they don’t really “go bad.”
If you’re not sure, you can always soak old motors in water and dispose of them, and get new ones. Or, heck, fly ’em. That’s what minimum safe distances are for! (Click here to see the Model Rocket Safety Code.)
“How Do You Fill the Seam Between Two Body Tubes?”
Some kits come with two short body tubes, instead of one long one, and you’re supposed to join them together with a tube coupler. A follower on Instagram asked the Rocket N00b, “How do you fill in the seam so it looks like a single tube?”
It can be done easily. But the first thing to ask yourself is if you actually want to do that. There are two good reasons not to fill in that joint.
The first is if the rocket is to be painted two colors, and the color separation coincides with the length of the body tubes.
Here’s one of the N00b’s favorite Estes rockets, the Cosmic Explorer. The top is black and the bottom white.
If you paint the rocket first, with the top black and bottom white, and only glue the tubes together at the very end, you’ll have a perfect color separation – a straight line, no bleed through of the black paint onto the white – and because of the color difference, you won’t see the seam.
The second reason is you might want to convert the rocket into a payload carrying vehicle. Some kits come with a payload section. Instead of a hollow tube coupler, they come with a balsa bulkhead called a nose block.
But even if there’s just a coupler, you can make your own bulkhead from heavy card stock, balsa, or basswood, add a small loop of Kevlar string, and now you have a payload section. Instead of blowing off the nose cone, the rocket will separate at the coupler during parachute ejection. You can fly your payload (such as an altimeter) in the upper section and keep it safe from ejection gasses.
The Estes U.S. Army Patriot is a perfect kit for this conversion. So is any kit with two tubes.
But if you do want to make one seamless tube out of two, you can use Elmer’s Carpenter’s Wood Filler.
Thin it until you can brush it on with a paint brush, and coat an area around the seam about two inches long. Once it’s dry, sand it smooth. Even if the tubes are a little uneven in their thickness, the wood filler can cover that up. The rocket will be slightly thicker in that spot, if you measure it with a digital caliper, but you won’t see it.
“What Kinds of Cameras Can You Put On a Model Rocket?”
A number of small video cameras can be attached to a model rocket to record the flight. A very popular kind is called an 808 keychain camera. This little “spy camera” looks like a key fob. They’re cheap and compact, and can simply be taped to the side of a rocket with electrical tape.
These little cameras range from very cheap (less than $10) to not so cheap (some cost between $70-90). Quality varies a lot, but even the cheap ones may be good for fun.
Little cameras like this can simply be attached to the side of a rocket with electrical tape.
MateCam seems to be a popular brand among rocketeers. Aside from video quality being on the better end, MateCams have a larger lens assembly. You can take one apart and arrange its guts to fit a special project.
The little cameras the N00b mentioned are called flash drive cameras.
There are a number of kinds of so-called “flash drive cameras,” but the ones referred to here can be found on eBay for less than $9.
Here’s video of the hidden camera payload rocket, the Ceres B booster with ICU2 payload, the design of which came from Mike Westerfield’s book, Make: Rockets: Down-to-Earth Rocket Science.
In this episode, we talk with Jim Parsons, who was once described as “the Chuck Norris of OpenRocket.”
OpenRocket is free model rocket design and simulation software which runs on Java. You can download it here, and play around with it if you’ve never tried it before.
OpenRocket is a great tool – and it’s free. But it does have its limitations.
If you make a sim of a kit, you might notice that it doesn’t look exactly like the kit you’re building. One big difference you’ll notice is the nose cone. All nose cones in OpenRocket (except for the elliptical ones) come to a sharp point, which isn’t the case in most model rockets. Usually nose cones are spherically blunted.
Now, for a flight simulation, this may not matter much. To find the center of pressure, model rocket simulators use what’s known as Barrowman equations, a system of mathematically locating the CP on a model rocket. These were derived from the math used in sounding rockets, and were published as an R&D report at Naram X in 196X by James Barrowman. (Click here to see the N00b’s interview with James Barrowman at NARCON 2017).
One of the simplifying principles of Barrowman equations are the assumption that all nose cones come to a sharp point.
But what if you want a simulation that looks like the actual kit? What if you’re trying to clone a historic, out of production model? Or you want a good reference for decal placement?
Jim has figured out how to trick OpenRocket to simulate accurate looking kits of all kinds. Some are quite challenging, because of features on the model that OR isn’t built to re-create. Check out this masterful sim of the Estes QCC Explorer.
While most of K’Tesh’s sims can be used for flight simulations, due to the limitations of OR, there is the occasional model sim which is mostly just for show. The A.C.M.E. Spitfire, by FlisKits, is one such example.
The N00b has used some of Jim’s files and images to figure out the decal placement and paint scheme measurements on a number of builds, like his recently-completed Semroc Bandit and Semroc Cherokee D.
Jim joins us from China, where he lives and works. He and the N00b discuss OpenRocket, chat a little about model rocket history, and the challenges of pursuing the hobby while living in China.