Robin’s Birthday Rockets HOWTO

*** You’re going to need about 12 hours to make this rocket *** I’ve seen (and done) hot-glue slap-dash rocket builds, and it ain’t pretty. But do what you can!

A note from Robin to her friends: I don’t want to say anything. fffffdfththth what does that say? what did you say? Why did you do that? ffffththththt hehehhhheeee hahaha why are you doing that Drew?!?! kkkkkkkkthththhththt you farted! kkkkheheheh what did that say Drew? WHat are you writing? what did you say drew? Why are you saying?? If it’s too loud, you should bring some headphones. Like these: amazon $13. Robin says the rockets aren’t too loud to me, but some kids might think so. And, by the way, there’s a Geocaching Headquarters in Seattle. I had a great time there! Here’s a pic.

The Facebook event for RSVPing. If you’re not on Facebook, no problem. Message myself or Alison using whatever method you’d like.

You should have one of two kits, the Fiesta (three fins, streamer recovery), or Tristar (two two-part fins, parachute recovery). You’ll make this in a few rounds of glue-drying, which is why it takes 12-24 hours.

Each rocket has it’s own instructions. These instructions and videos are additional tips, pics, and videos for helping things go a little smoother.

First round gluing and assembly

Engine mount – for the engine mount, you’re going to measure a length and make a small incision in the tube that one end of the motor clip will go into. The other doughnut looking things will hold that metal clip in place. Put a light bead of Elmer’s glue along the top and bottom sides of both doughnuts, so four beads total. There’s a single smaller doughnut that is going to go inside the top end of the tube. Put a light bead of glue in the engine tube, and twist slide that guy into place. It should butt up against the piece of the metal clip that’s protruding into the engine tube.

Slide on engine mount rings video
motor mount video

Recovery system – both versions of rockets will have a small polygon cutout. Use plenty of glue to wrap the shock-cord up into the tri-fold of that paper polygon. Once you squish it together, glue will be coming out, that’s good. Put a small weight on top to hold it while it dries. You can attach the parachute to nose-cone, or streamer to shock-cord at this point also.

Launch lug – This is what holds the rocket prior to lift off, and gives it it’s initial direction from the launch rod. It doesn’t have to be perfect (none of this does!)

end of first round video

Second round of gluing

Fins – one of the more tricky parts of construction. There are two main tips here for fin: use a door jam with the tube and pencil to make your lines. And second once you get the fin on, lean it against something to sit basically correct while the glue kicks. Between those things, just eye-ball it, you should be close enough. Each fin requires one round of glue and wait. A video of course

Engine mount – you should use a leftover piece of balsa wood as a glue paint brush. Make a couple marks on the tube with the engine mount, so you can visualize where the mount rings will be inside the body tube. Hold the piece of balsa wood up there where you should wipe the glue on the upper engine mount ring. While the piece is on the outside, it’s easy to see how far you should put it in there. When you put some glue on the stick, you can stick it up there to your mark, and start wiping it around the inside of the tube. Stick the engine mount up in there, before the second ring goes in, cover that with glue all the way around. Up we go, and bob’s your uncle. A video of what I’m talking about.

Shock-cord and nose cone to the body tube. The folded-paper end of the shock cord has to be at least far enough into the body tube so the nose cone can slide cleanly into the body tube. Be careful not to get any glue on the part of the tube the nose cone will be in contact with. Ideally, the nose cone would fall out of the rocket if you turn it upside down. Bend that tri-folded piece of paper so it pretty much holds the shape of the inside of the body tube. Put some glue on the outside of the paper, and give it five minutes to set up. Carefully put the paper into the tube, and pinch it against the inside of the body tube. Once you release it, it should stay right where it’s at. If it bends away from the inside of the tube, just keep holding it. Mounting video

the finished rocket

Engines, velocities, and other fun facts

I’ve got this neat rocket simulation program. It will give me a good idea of what to expect from various rockets, if everything else is nominal (normal).

Estes black powder rocket engines have been around for years. They are divided up by both diameter and impulse. Impulse is how much a thing pushes. The first part of the designation is a letter then a number (B4, B6, 1/2A6) signifying the impulse. Then it’s followed by a dash, then another number. The second number is the delay between engine burnout and the parachute charge blowing out. Ideally you want the parachute to pop out right at 0MPH, after the engine burns out, the rocket finishes coasting and the “nose over” point happens as it starts to head back towards Earth.

1/2A6-2: apogee 152ft, velocity at deployment 20MPH, max velocity 75MPH, max acceleration 812 ft/s^2, time to apogee 2.7 seconds, flight time 19 seconds

B4-5: apogee 832ft, velocity at deployment 9MPH, max velocity 220MPH, max acceleration 1116 ft/s^2, time to apogee 6.3 seconds, flight time 90 seconds

B6-5: apogee 834ft, velocity at deployment 11MPH, max velocity 234MPH, max acceleration 1088 ft/s^2, time to apogee 6 seconds, flight time 90 seconds

C6-5: apogee 1480ft, velocity at deployment 11MPH, max velocity 341MPH, max acceleration 1095 ft/s^2, time to apogee 7.5 seconds, flight time 156 seconds

apogee: highest point, velocity: speed, ft/s^2 a measure of acceleration “feet per second squared” or “feet per second per second” aka positive number gas pedal, negative number brake pedal

The thing you can notice here is how LONG some of these rockets spend on their parachutes. All of that time they are susceptible to sideways winds, only going where the wind pushes them. The longer they spend on their chutes, the more likely we’ll lose the rocket. So, depending on the day, we may not get out the bigger engines. And it’s ALWAYS a good idea to acknowledge that every rocket flight is saying goodbye, and we’re lucky if we get to fly again 😉

clear rocket engine video
SpaceX Falcon Heavy flight animation video (Robin loved this one)
John Kraus photos of rockets how to make a rocket newtons three laws of motion