Now the rocket has a name!

Ken, of Delanco NJ made several of these rockets using colored posterboard for the body tubes. His kids chose the colors, and his daughter Kristen gave them a clever and charming name.

So with her kind permission, I hereby christen this rocket model the "Snap Dragon."

Thanks, Kristen!

Body Tubes

Made from posterboard and spray glue, they are quick, cheap, easy, and sturdy. Can be made lighter, at the expense of some sturdiness, or heavier, for greater strength.

This technique is adaptable to many other rocketry uses, such as inhibitor tubes, case liners, and small motor casings.

Nose cone

Sure, it's nice to have a wood lathe. But you don't really need one to get started. These cones can be "turned" with agile fingers from a 3x5 card, and are reinforced with epoxy. For what they lack in aerodynamics, they make up in simplicity and strength.

Fins

I use a simple, functional design, subject to aesthetic and perhaps aerodynamic improvement. Includes making and installing the launch lugs.

Body Covers

An easy way to create a fancy "paint job" for your rocket.

Finalizing

Thrust ring, shock cord mount, recovery streamer, motor retention, and launch video.

Rocket Science 101

Photos of the October class launch, where this model was tested a number of times.

Everyone in the class assembled at least one rocket, some made more than one. On launch day, they were flown using Estes motors.

Except for some ejection failures, they all performed well and proved sturdy enough to survive a "lawn dart" recovery to fly again. I believe that my new motor retention system will solve the ejection problem, we shall see....

Gallery

Here's one by Geoffrey Andrews which he has named Moonstone. I like that name - it matches the colors well. The tube is carbon fiber, both lighter and stronger than the paper tubes I am using. This one should really fly.

Thanks Geoffrey!

Tubes are made from posterboard, sprayed with glue, and rolled around an appropriately-sized dowel which has been covered with a relatively non-stick material.

Inside diameter is a little over 3/4 inch, outside diameter just under 1 inch. Length is 11 inches, weight is 25 grams.

It took about 5 minutes to make these four tubes, at a total cost of about 50 cents.

Primary material: posterboard. This kind is easily available here. I can buy it at the supermarket for $0.59 per sheet, or at the office supply store in packs of 10 sheets for about $4.00.

Each sheet is 22 inches wide by 28 inches long. Measured with a micrometer, it is 0.012 inch in thickness. One sheet will make four body tubes.

I have found many uses for this stuff lately, inhibitor tubes, case liner tubes, motor casings, epoxy mixings.....

Alternative: One can use plain copy paper to make tubes like these. It would take 4 or 5 sheets of copy paper to make one of these tubes. When made with Titebond glue, these are very strong, although not always very straight.

3M Super 77 Spray Adhesive. Guess you could have read that from the can. This is a medium-weight spray glue which works very well with paper and light wood adhesion.

It costs about $7.00 per can, and is available at most hardware stores here.

Advantages:

• - Adheres upon contact. Tubes do not need to be secured while the glue dries.
• - Tubes dry quickly, can be used within minutes.
• - The solvent does not soften the paper like water-based glues do, so the tubes are much straighter and smoother.

Alternatives: I have used white glue and water-based wood glues like Titebond for years in making such tubes. I still use Titebond for motor casings, as it makes for a stronger tube. 3M General Purpose 45 spray adhesive works OK. It's not quite as tacky as 77 so is a little more difficult to use for nose cones. 3M High Tack 76 is a much thicker, heavier glue that shoots out of the can in stringy blobs. It might be good for gluing plastic laminate onto countertops, but it is not suitable for this purpose.

Other spray adhesives may work for this project, but these are the ones I have tested.

Double-stick tape is sticky on both sides. One of its more common uses is for mounting photographs in albums.

How is it useful here? Well, Super 77 is a contact cement. It adheres immediately. If you spray any part of the posterboard that will contact the rolling dowel, it will glue to the dowel and won't slip off without a struggle. So the first turn of the roll is secured with tape instead, then the remaining posterboard is sprayed with glue and rolled up.

Alternative: You can mask one side of the sheet and spray only the part that needs to be glued. This might actually be the better technique, see below.

Dowel sizes are:

3/4 inch diameter, for making the body tubes themselves.

1/2 inch diameter, for making coupling tubes

1/4 inch diameter, for pre-rolling the posterboard

The two larger dowels should be covered with something that makes them less attractive to glue. In the photo, note that the largest dowel is covered with Nashua 324 aluminum foil duct tape, giving it a metallic look. The 1/2 inch dowel is covered with red plastic-wrap. Both work OK.

The 1/4 inch dowel is not covered with anything, it just looks that way. It is painted flourescent pink. I use these as stabilizing sticks for crude motor tests, and I like to be able to find them. They are hard to look at, but easy to see.

A sheet of posterboard is cut into four equal rectangles, each 11 inches wide by 14 inches long. Each rectangle, rolled the long way, will make one body tube 11 inches long.

It is important to pre-roll the posterboard at both ends, to make it "want" to roll up. Just wrap the edge of the paper around the 1/4 inch dowel and force it to curve around the dowel as smoothly as possible.

It will resist. Persist. Get it curved all the way to the edge of the paper. A smoothly curved edge now will make a smooth, easily-rolled tube, which will not need to be rubber-banded to hold it together. Rubber bands make little ridges.

If you don't pre-roll, you will have trouble at both ends. At the first end, there will be difficulty getting the first roll tight on the dowel, and the tube will not be size-conformal. At the finish, the final edge will want to pull away from the tube, and you will have to rubber-band it or something to make it lay down. Pre-rolling pre-empts these predicaments.

Having done all that strenuous pre-rolling, it is time to unroll one of the ends and flatten it a bit. That is so we can put double-stick tape on it.

A strip of double-stick tape is torn off just a little longer than the width of the posterboard. It is stuck to the edge, and the ends trimmed to the edge of the posterboard.

The taped edge is curled over the 3/4 inch dowel, tucked in evenly, and the first roll made.

The double-stick tape secures the first turn of the tube, making the spray-glue operation much simpler. Note that the far end of the posterboard is not properly tucked. It was the best I could do and still get a photograph. Rest assured that error was corrected before I actually did the roll.

Remove the dowel from the tube to keep it from getting glued.

The first turn is now secured with double-stick tape.

It is protected from the adhesive spray.

I guess you could mask the dowel with tape and not have to take it out. But I haven't tried that yet.

Take the paper to a spot you don't like and spray it with glue. It doesn't take much, but do strive to get an even coating.

Take it back to the flat rolling-board, re-insert the dowel, and roll it up.

The finished tube can be worked within a few minutes. Here I am holding it to a fin-attachment guide, which is used to space out the fins at the right interval and to get them on straight. But we are getting a bit ahead here.

A smaller tube is made in the same manner, except this one is a strip 20 inches long and wrapped around a 1/2 inch dowel. 20 inches of posterboard makes for a nice fit inside the 3/4 inch tube. It slides in with just a little resistance, so it will glue in well. This tube will be cut into short sections to make the motor thrust-ring.

Such close fits can also be used to make extended airframes, either as coupling tubes to add another 3/4 inch ID tube, or by itself to make a reduced-diameter upper airframe. But beware! Long, skinny airframes make ejection more difficult, and lawn-darts are common with this model already.

Just in case you don't have any double-stick tape lying around, or have a yen for doing things the old-fashioned way...

You can mask the side to be rolled around the mandrel. Just draw a line 2.375 inches (2-3/8ths) from one edge. Pre-roll it and mask it with something.

Here I am using a scrap of posterboard and green masking tape. Spray the remainder with Super 77, remove the mask, and roll it up! Starting with the unglued end, of course.

Actually, now that I have tried it again I realize that this works very well. Forget the double stick tape. Make that two essential materials.

I start by making a mark in the middle of one long edge of a 3x5 index card. This is where the apex of the cone will be, and the mark reminds me of its location.

To get the angle right, I make a mark on the other edge 1 inch from the side, and draw a line between the two.

Sometimes words don't do justice, so here is a drawing. Mark the overlap line as shown. Mask the card to the left side of the line, spray the other side, and roll. This will make a nicely-proportioned cone for this airframe.

The far edge is pre-rolled on the 1/4 inch diameter dowel. This gives it a bias toward curving, both on the inside and the outside flaps. This will help make a smooth roll once the glue is applied.

Inside curl will help to keep the cone round, as a straight flap will tend to distort the tube into an ovalish cross-section.

Outside curl will help that flap lay flat upon gluing, rather than (un)curl up.

Top-left side is bent down to make a partial fold as shown. This is the start of the cone.

The cone is pre-rolled to something close to its final form.

What's wrong with this picture? It was taken before I pre-rolled the edge. Note that the final flap wants to fly. It must be convinced to lay flat, that's why the pre-rolling is done.

Having done my pre-rolling duties, I may proceed.

Another card is used to mask the first section of the nose cone card. Masking is not absolutely necessary, one could just spray the whole card. I did that on the first few, but Super 77 is sticky stuff, and rather annoying to have on one's fingers. Makes it hard to let things go.

The cone is rolled again, this time with the glue. Since the final flap has been pre-rolled, it lays flat of its own accord. Be sure to check the inside and make sure the inner flap is pressed firmly against the inside of the cone.

The cone will be mated to a body tube. To give it a better gluing surface, I sand the end of the tube at an angle which will match the taper of the nose cone, more or less.

(Hey! a thought.... cut the body tube edge at an angle so that it rolls "stair steps up the ziggurat" with an angle that matches the cone... I haven't yet tried this, but will!)

Here is that taper I mentioned. It should provide a larger gluing surface, mating with the paper cone better than the original sharp shoulder would, right?

Posterboard does not sand cleanly, but that's OK. The fuzzy stuff is of no consequence, it will be removed later.

Remember that idea of cutting the posterboard at an angle? Well I did it, and here is the ziggurat.

After sanding one to the point that it fit "right," I measured the depth of angled the edge and found it to be 1/4 inch.

The board is cut so that one end is 1/4 inch wider than the other. It is 11-1/8th inch wide on the starting end, 10-7/8ths inch wide on the far end.

Less sanding is needed, and the fit is better. I'll keep this idea!

The dunce cap fits nicely on the tube, and stays put just from friction. Here I am marking the spot on the tube where this part of the cone comes....

Marking the spot where the body tube will reach. I will trim the cone back just a little short of that mark.

Cone is trimmed to within 1/4 inch of the mark. Better a little too long than too short. It's a lot easier to take more off than to add it back later.

A generous glob of white glue is applied to the end of the body tube, and smeared evenly.

OK, now don't get upset that we have changed body tubes here. This is show biz, and these photos were made during several different "shoots." My bad for not using a plain white tube every time, to save that much distraction and confusion.

I'll tell you all about the the pretty tube later.

Moment of truth. The cone is pressed onto the tube. Is is straight? Must find out quickly!

Apologies for the bad photo, but this shot is kinda hard to do.

Sighting down the length of the tube, I noted that the center of the point (bright dot) was not perfectly centered. So I adjusted it a bit. Get that dot exactly in the middle!

Second test for straightness: While the glue is still soft, I hold the body tube loosely in my right hand and spin the assembly from the cone tip. Notice if it wobbles, and how much. Adjust until there is no perceptible wobble, at which point the cone is straight. Whew!

Here is perhaps a better way to get the nose straight, and doesn't require quite the motor coordination of the previous method.

Lay the tube on a flat surface with the nose cone overhanging the edge, get down there with it, and roll the tube. If the nose cone is not centered, the tip will appear to bob up and down.

Nudge it a little towards the middle.

Roll it until the tip points down as far as it will, and move it up a bit. Roll it again. Straighten it again. When the tip rolls in a straight line, leave it alone. Let it dry.

Here is a video of me doing this one. (1.3 meg .mpg file, 15 seconds of video)

There is a bit of overlap, as planned. I must confess, I had already started sanding when it occurred to me to take this picture - note abrasion on the left side.

Here is an alternative to the pre-trimming. You can glue the whole cone on, big flange and all. Then take a very sharp knife, or a good serrated knife, and trim off the excess by slicing along the body tube. This is kinda crude, but it usually works OK.

The shoulder is sanded with 150 grit or finer sandpaper to remove what remains of the skirt and make it all even.

More or less even, if a bit rough. Note that the overlap has been sanded to reduce its obtrusion.

The magic of wet-or-dry paper. Here I am using 400 grit to smooth the cone and its shoulder. This will remove the frass and make the whole thing pretty darned smooth.

But it is still porous. So I smear a layer of Elmer's glue all over the cone. This will seal and harden the surface. Let that dry for 15 minutes, and smear on another coat. That will make it smooth, glossy and much stronger. But not strong enough. It needs the third glue! We will get to that shortly.

Now the nose cone is stuck firmly onto the end of the body tube. This might be OK for a pyrotechnic rocket that goes up and blows up, but that's not what this is about. Proper recovery is required, and that means the nose cone must come off to eject a parachute or streamer. So we will separate the cone from most of the tube.

Remember the silvery dowel? It's the one used to roll the body tubes. I will use it here to assist in cutting off the nose cone.

The dowel is inserted into the body tube until it reaches the nose cone. This will support the far end of the body tube while it is being cut.

A long, sharp knife is laid on the body tube about 1/2 inch from the base of the cone, and rolled carefully back and forth to make a groove. Once a groove is established, more pressure can be applied as the knife is rolled, eventually cutting through the body tube.

Click Here for a movie of me doing this with another tube

(1.3 meg .mpg file, 15 seconds of uninspiring but perhaps informative video)

Finally, the nose cone is set free. Note that the overlapping paper has been sanded down and filled with glue-coats until it is barely visible.

For now, it is just a thin, fragile paper cone. Compromised in places by sanding, but still intact. We will make it strong with the third glue, epoxy.

A section of 3/4 inch dowel is cut to serve as a base.

Some 5-minute epoxy is mixed up, perhaps a teaspoon. The entire interior of the paper cone is coated with this glue. I make sure that it coats the very tip of the cone to seal its small opening, and lingers in the shoulder where the short section of body tube meets the 3x5 card cone. Any glue left over is dumped in the cone and spread around the perimeter, preparing for the next step:

Dowel is inserted in the cone, with 3/4 inch protruding. The picture is deceiving - I coated the end of the dowel with epoxy before inserting it, to make sure it is glued really well.

The nose cone assembly is stood upright on its base while the epoxy cures. This is so it will drip down, reinforcing the shoulder where the cone meets the tube and the paper is the thinnest.

This may cause the glue at the tip to drain down, opening it up again. If that happens, give it another drop of epoxy after this first application has set.

A screw-eye is added to give the shock cord something to hang onto. This is actually a different cone - note the paper base. It has a 1/2 inch wooden dowel for a core.

You can argue with the aesthetics. You can argue with the aerodynamics. But this is definitely a cost-effective procedure... once you have bought the three glues!