Paper Towel Rocket Challenge
 

Hi Gang,

This is my first post, though I have been lurking and searching the forum for some time. I certainly have enjoyed learning by reading posts and appreciate those so willing to share their knowledge. I became a BAR earlier this year while in a hobby store with my sons to pick-up something else. Just passed the rocket display and that was it!

I find myself teaching a basic model rocket course to a group of students to highlight science and math concepts. Part of the course is to make rockets (except motors) from common household materials - body tube is to be a cardboard paper towel roll. The only cost to students will be a couple of motors. So I would appreciate any help on a few issues:

1. does anyone have any tricks, tips or suggestions for making centering rings for motor mount tubes (material suggestions too)?

2. does anyone have any rule of thumbs developed for card size used to make a nose cone relevant to the body tube diameter?

3. does anyone have any 12-inch parachute templates they would be willing to share (i.e. pdf or word format)?

4. does anyone have a rule-of-thumb for length of shock cord relative to size of parachute?

And if anyone else has successfully made a paper towel rocket and wants to pass along any suggestions, please do. Given the students are in a group setting, I'm trying to keep things simple.

Thanks,

Douglas

Shock cord length has more to do with the sustainer body and nose cone than with the chute.

And you only have too much if you can't get it into the rocket.

I have no magic solutions and can never keep track of the weight of the cardstock I've used, but here goes (numbered per you questions).

1. At a paper towel roll size, many sources of free card stock will work. Consider cardboard from shoeboxes or even corrugated cardboard. If you feel the material is too flimsy, have them make two (4 total) and glue them together. I use a lot of foamboard. It's easy to work with and you can make tons of rings from one sheet. Get a circle cutter from a craft store.

2. By size do you mean weight or thickness? For a simple conical cone, the weight of note cards will work. Or get a big sheet of posterboard from a crafts store (with the foamboard and circle cutter). Get a shroud template tool from EMRR to make the patterns. http://www.rocketreviews.com/tools.shtml

3. Can't help, sorry. They are around so someone will give a pointer.

4. Use 2 -3 times the rocket length.

Paper towel tubes have been my primary source of body tubes since I started building and flying rockets a hundred years ago. Attached are some pictures of some recent ones. Most are paper towel tubes but some are toilet paper, wrapping paper, etc.

1. I make centering rings by first creating a pattern in MS Publisher by measuring the inner diameter of the BT and the outer diameter of the motor tube. I like Publisher because you can "snap" the circles to a corner and have them aligned perfectly. I print the rings, glue them on cereal box cardboard with a glue stick and away we go. That method has worked great for me for years.

2. For nose cones I generally use plastic easter eggs or similar items. I make a coupler with cardstock, rough up the inside of the egg with coarse sandpaper, and glue the coupler in with regular wood glue. Some on these forums have chastised for gluing paper to plastic with wood glue because it doesn't form a real bond but, as before, the method has worked well for me.

For what it's worth. :)

Wow - thanks for all the suggestions everyone! I'm already working to incorporate and try them out.

And thanks for sharing pictures too - very inspiring!

Douglas

You can also use shorter segments of paper towel tubes to make tube fins. Then use Easter egg nose cones as previously suggested and the basic cost goes to almost zero (before the motors).

I don't have time at the moment for a lot of info, but I've been making a couple of kits from PT tubes for decades.

I use a 9 inch BT-20 for the motor mount tube so that it acts as a stuffer tube AND prevents the delay afterburn from igniting the PT tube (it ain't normal body tube material, after all).

I use the round half of Ester eggs. I have hundreds of them available for virtually nothing (mainly the shipping cost).

I have instructions on how to make the parachutes, how to make the fin lines, etc. No PDF. purely xerox. I can include a sheet with an egg order.

I can even include a complete bagged kit for $10 if the egg order is large enough. Then you can duplicate.

And yes, I've also make cluster versions as well as 24mm versions with tube fins. The standard models use balsa fins.

For any other newbies like me just getting into scratch building, I found EMRR's "Comparison of Free Paper Rockets" to be helpful in showing various approaches. It was interesting to read through the designs of each rocket. Also, reading the EMRR review of each design gave me additional insights too. Hopefully saves me a few mistakes! ;)

Douglas

Paper towel rockets are fun, great fliers and cheap, cheap, cheap. I'm having a sleepover for my 7yro girl this weekend and part of the party (6 girls total) is building rockets and flying them on Sunday.

Some cardstock and basic rocket building knowledge required

My build list for each kit consists of:
1 paper towel tube
2 toilet paper tubes (6 cuts at 30mm long)
cardboard
110lb cardstock
24" of 1/8" elastic shock cord
easter egg
metal strip from windshield wiper
trash bag
kit string or dental floss
two fishing swivels

As stated, the toilet paper tubes are cut to 30mm length, two pieces are glued together 3x(held in together w/paperclips ) before attaching to body tube where the three pieces are then held to body tube with paper clips while glue dries.

Centering rings are cut with a circle tool (available for $8-$10) out of cardboard. 13mm or 18mm holes are also cut in center for engine mount.

Motor tube is rolled out of 110lb cardstock....double wrap.

Engine retainer clip is bent out of metal strip from windshield wiper.

Once installed into centering rings, motor assembly is glued flush with bottom of paper towel tube leaving approx 1/4-1/2 of motor sticking out.

As mentioned in a previous post, inside of easter egg is scuffed to better adhesion for glue. Nose cone shoulder is cut out of 110lb cardstock approx 1.25" long (double wraped) and attached with Testers plastic cement.

Shock cord is fastened to inside of easter egg and body tube by tri-fold method. Plastic cement for egg, white or wood glue for body tube.

Launch lugs are rolled from cardstock. If enough room bottom lug can be attached in gap between fin tubes against body tube. Second lug attached 1.5" from top of bt.

Parachute is cut 12" x 12" out of black or white trash bag w/appropriate length string. Spill hole can be cut if needed.

Tie a loop in shock cord approx 4-5" from edge of nose cone shoulder. Attach one swivel to end of kite string that is approximately 12" long. Attache other swivel to opposite end of kite string and thread through loop in shock cord. Thread loops for parachute through opposite end. Very nice recovery using this method.

13mm versions require no nose weight, fly straight and stable to about 200'. I have not built the 18mm versions but will be doing so this weekend. I don't think any weight will be required for "A" motors but assume will be needed for B's and C's.

If you really want to have fun and show the kids something, I've built one out of two paper towel tubes and one toilet paper tube to make up the body, tube fins close to the shape of the Kraken, easter egg nose cone, baffle and three 18mm cluster. Flies great.

Great post El Cheapo! Thanks for taking the time to outline your building process - very helpful. If you get any rocket pictures from your build weekend please post! Six 7 yr old girls in your house...man you're brave!! ;)

Just a few questions:
1. Forgive my brain freeze, but I'm not getting your first step with the toilet paper tubes. I'm a bit lost to understand the 6 cuts and what role these tubes serve.

2. Have you found a particular size of Easter eggs to work best?

3. Have you found a cheap source for the windshield wiper part?