As anyone invovlved in the hobby of model rocketry already knows, commercially manufactured model rocket engines cost a bloody fortune, it is much more practical and much less expensive for you to simply make them yourself. You can make them from materials available to anyone at your local drug, hardware, and grocery stores, and they'll cost you very little each.
Simple and inexpensive to make, these little beauties will take a featherweight model 200 to 300 feet into the air. A small investment will buy enough supplies to make several hundred rockets, and each one will do anything a commercially made engine will do including igniting second stage rockets and popping parachutes. Here's how to make them. If you don't already have these items around your house, go out, hunt them down, and purchase them as follows.
Go to the local drug store or chemical supply company and buy a small container of saltpeter and a small container of flowers of sulfur. Saltpeter is also known as potassium nitrate. Both chemicals are over-the-counter items and do not require a prescription for purchase. In most cases you'll find them in the patent medicines section along with the glycerine, calomine lotion, witch hazel, castor oil, etc. In some stores, due to shelf space considerations, the pharmacist will keep them in the back. If your local pharmacist does not stock these items, speak to the pharmacist, and he will probably be happy to order them for you.
The saltpeter will come in a 4 to 6 ounce container, and the sulfur will be packaged in the 2 to 4 ounce size. One package of each is sufficient for at least one hundred rockets!
Next go to the local supermarket and purchase a small package of powdered white confectioner's sugar, also called iceing sugar. Sugar is the fuel in the rockets you'll be making, and saltpeter (potassium nitrate) is the oxidizer. The sulfur plays a role in releasing various gases during the rocket's flight, thus raising propellent impulse and improving rocket performance in general. Combine these three substances in the following proportions by weight.
SALTPETER...........................63% SUGAR...............................27% SULFUR..............................10% It has been reported that you can use red iron oxide in place of the sulphur
Ideally you should have some accurate weighing equipment (a triple beam laboratory balance), or a gun powder scale, but if you don't, a simple postal scale or diet scale will do. If you're involved in reloading your own rifle and shotgun shells, your reloading scale will work nicely. Postal and diet scales can be bought in most large department stores for about $5, and the more accurate you measure your ingredients, the better your rockets will perform.
These little rockets were designed to fly with a very low impulse propellent, and we wanted to make the mixing process as simple and safe as possible, so here's what we came up with. Place the properly measured chemicals into a small plastic refrigerator container with a tight fitting lid (a half pound or one pound soft margarine container works great). Break up any lumps ahead of time with the flat end of a large wooden dowel or screw driver handle, tighten the cap onto the container, shake the ingredients in the container vigorously together for about three minutes, and you're done!
WARNING Never attempt to mix the above-listed chemical together in a blender or any kitchen appliance designed for mixing or grinding food! Friction will generate heat, and a blender can rapidly (in the vivinity of the bearing and blades) cause the mixing powders to reach the ignition temperature. Six ounces of these chemicals in a blender can cause a flash fire large enough to set fire to your entire kitchen, and after that, your house! As we said before, we've designed these rockets to use low impulse propellent, and the lenght of the core in each engine is just about right to handle the mixture that you've prepared from the instructions above.
NEVER attempt to load one of these homemade rockets with anything other than the properly prepared propellant described in this report, and never attempt to convert or reload a commercially manufactured motor with this homemade rocket propellant!
The finished propellant will be a pale yellow colored powder, and if you were to simply load it into a cardboard tube with a hole in one end, it would burn too slowly to allow a rocket to fly. In order to use this slow-burning material to propel your device into the air, you have to get the powder to burn all at once, and you do this by introducing a core or bore hole right through the middle of the propellant charge and igniting the propellant all along this core all at once. Once you've done this, the propellant will burn along its entire length beginning at the center and burning outward to the inside wall of the motor casing. Rockets constructed in this manner are called core-burners, and they are ideally suited to the use of slow-burning, homemade, low impulse propellants.
This particular mixtures of chemicals is hygroscopic. That is, if left in an open container, it will absorb moisture out of the air and dissolve itself in it. If you don't keep the propellant container tightly sealed, your propellant will get damp and not burn properly, but if you keep the lid on, it can be stored indefinitely.
Here's an actual recipe you can use. It will make a little over 6 ounces of rocket propellant, and since each rocket only uses 3 to 4 grams, it is enough to make about eighty rockets. For those of you with metric weighing equipment we've written the recipe in grams.
SALTPETER..................113.2 GRAMS SUGAR.......................48.5 GRAMS SULFUR......................18.0 GRAMS
Remember when you're weighing things that you must subtract the weight of the container in which you are weighing them. We suggest the use of small, thin, lightweigth sandwich bags. They seem to work just fine, and they're about the right size for the recipes written above.
Method 1 Long and detailed description
While you're at the supermarket buying the powdered sugar, go to the stationery section and buy a 2 inch wide roll of gummed brown packaging tape. We found ours at the local drug and variety store, the same place where we bought the chemicals. It's made of the same material used in the construction of brown paper shopping bags. It's coated on one side with water soluble dextrin glue. The $0.99 roll we bought was 75 feet long, and that's enough to make about 100 rocket casings.
To make an engine casing, proceed as follows. Cut a one foot length of 1/4 inch diameter hardwood dowel (available at a hardware store), and cover it with several strips of scotch tape. For reasons that you'll understand later, the inside diameter of the casing has to be a little larger then 1/4 of an inch, and the layers of scotch tape will build up the diameter of the dowel just enough to give you the proper finished engine casing indide diameter.
Next cut a strip of gummed paper packaging tape eight inches long and lay it, gummed side down, on a smooth, flat surface such as a kitchen counter top. Dampen all but the last inch of the back of the tape with a wet sponge. Remember, DON'T wet the last inch of the tape.
Now turn the tape over and starting at the dampened end, begin rolling it up around the scotch-tape-covered dowel. As soon as you've gotten one layer of tape around the dowel, moisten the gummed side of the rest of the tape and roll it up around the dowel as tightly as you can, like a jelly roll or a window shade. You may have to experiment a bit with just how much to dampen each side of the tape, so reconcile yourself to wasting a few strips of tape in the beginning.
Some brands of packaging tape are made from a kind of paper that sort of falls apart if you handle it when it's wet. We told you to leave the last inch of the back of the tape dry. That was so that it would not start to roughen with handling as you finish your rolling and remove the casing from the dowel.
Your biggest problem will be telescoping. That is, as you continue to roll, the paper tape will start to run off to one side or the other. When this begins to happen, you can correct it in the following manner. If, for example, it is starting to run off to the left, then use a single edged razor blade to slit the unrolled portion of the tape right next to the roll. Start the slit at the left edge of the tape and cut across the tape to within 1/4 of an inch of the right edge. Once the tape has been partially cut, you can pull it to the right and correct the error. If the tape starts to roll off in the other direction, reverse the instructions given above. With a little practice in rolling you'll be able to reduce your errors to a minimum and eventually eliminate the need to make these corrections. When you're done rolling a casing, hold the last edge of the tape firmly against the counter top for a few moments to be sure that it is thoroughly glued down; then slide the finished casing off the dowel and set it aside to dry.
Before proceeding to the next step these finished casings should be allowed to thoroughly dry. They will air-dry overnight, but if you're in a hurry, you can bake them in your kitchen overn at 160 degrees for a half-an-hour. The finished casings should have an inside diameter of a little over 1/4 inch, an outside diameter of about 3/8 of an inch, and a wall thickness of about 1/16 of an inch. The ends should be resonably square, and they should be as close to 2 inches long as possible. Slightly inferior casings can be trimmed square and to length with a single edged razor blade once they're dry.
Method 2 Short desciption
SMALL ROCKET ENGINE CASINGS ARE EASY TO MAKE.FIRST MAKE THE CASE FROM THICK PAPER CUT A PEICE 2 INCH WIDE BY 6 INCH LONG,GET A 1\4 INCH FORMER,GET SOME WHITE PVA GLUE AND BRUSH ON A VERY THIN LAYER LEAVE A SMALL DRY AREA SO IT DOES NOT STICK TO FORMER, TO MUCH AND IT WILL SLIP WHEN ROLLING PAPER. YOU GET A 2 INCH TUBE ABOUT 3/16 THICK OR SO,NEXT YOU MAKE A SMALL TOOL. GET A PEICE OF 1/4 INCH FORMER IF IT IS HOLLOW BLOCK THE END UP,INSERT THE FORMER INTO THE TUBE (WHEN GLUE DRIES) 1 AND 3/4 INCHES NOW WRAP SOME MASKING TAPE AROUND THE END OF THE BIT OF FORMER HANGING OUT THIS NOW IS YOUR DEPTH GAUGE, NOW YOU MUST MAKE A NOZZLE FROM SOME WATER PUTTY THAT SETS HARD AND DOES NOT SHRINK CHECK YOUR HARDWARE SHOP!,MIX THE PUTTY INSERT THE DEPTH GAUGE, AND PUT IN A 1/4 INCH BLOB TO MAKE THE NOZZLE,REMOVE THE DEPTH GAUGE SLOWLY BECAUSE THE VACCUM WILL SUCK THE PUTTY THROUGH. WAIT TILL THE PUTTY DRIES, NOW DRILL AN 1/8 INCH HOLE IN THE MIDDLE CAREFULLY. YOU NOW HAVE A CASEING WITH A NOZZLE.
Go to the hardware store and purchase a small can of rock hard water putty. It has different brand names around the world just ask the hardware store for water putty, While you're there, also pick up the following items:
1.One package of epoxy glue(part a and part b) 2.A few ungalvanized nails, 3/32 of an inch thick 3.One length of 1/4 inch diameter hardwood dowel 4.A 7/64 inch diameter drill bit 5.A 1/8 inch diameter drill bit
We bought the smallest can of water putty they had, and it is more than sufficient. water putty is an old standby in most hardware stores and is commonly used for filling holes in wood and patching cracks in plaster. It sets up extremely hard, and unlike other wood and plaster fillers we tried, it doesn't shrink! If the first place you go doesn't have it, look around in a few other stores. It works better than anything else you'll find, and it won't dull the drill bit used to make the nozzle holes.
The nails are about 3/32 inch in diameter. You form the core of each rocket by packing the propellant down around one of these nails, then removing it when you're finished. All finishing nails have a little row of shallow grooves right near the head that will cause you some minor problems as you pull the finished rockets off the nails. These little serrations will tend to hold and tear out a bit of the propellant. If you live near a hobby stop, you can buy a length of 3/32 inch diameter piano wire (used to make model airplane landing gear). You will have to cut it with a grinding wheel (it's much too hard to snip with wire cutters), but it is smooth along its entire length and will make better coring mandrel than a nail.
As we stated before, the nozzled are made from rock hard water putty, and to make one you're first going to form a little 1/4 inch long plug of putty in one end of each paper casing. To do so you're first going to make yourself a little depth gauge to be sure the plug of putty in any given rocket doesn't extend deeper than the required 1/4 of an inch.
Cut off a six inch length of the 1/4 inch hardwood dowel that you just bought and wrap a dozen or so layers of regular masking tape around it so that one edge of the masking tape is exactly 1-3/4 inches from one end of the dowel. Slide a paper rocket casing over the dowel and run the end of it up against this edge of the tape. If you now look into the open end of the casing, you will see a cavity exactly 1/4 of an inch deep, and you must pack this cavity full of durham's putty.
Mix the putty with water in a small container to the approximate consistency of stiff bread dough. You can pack each cavity by simply pressing a wad of putty into the end of the casing with your finger and wiping the excess off with your thumb. Press the putty firmly into the cavity, and try to avoid creating bubbles or air pockets.
When the cavity has been completely and firmly filled, slowly withdraw the dowel depth gauge. Please not that we say slowly, turning slightly can also help, If you pull too fast, the suction created by the pulling action will suck the putty down into the motor casing, and you'll have to start over again. Remember that when you rolled the casings in the beginning we told you to make the inside diameter a little larger than 1/4 of an inch. We did this so that the dowel depth gauge and the 1/4 inch diameter powder tamp you'll be using in the next step would slide easily in and out without binding.
Rock hard water putty dries quite slowly, and you should let the plugged casings sit overnight before proceeding. You can, however, speed-dry them by laying 50 or 100 of them on a cookie sheet in your oven and heating them at 140 to 160 degrees for an hour to an hour and a half.
Once the putty is hard and dry, drill a 7/64 inch diameter hole completely through the center of each dried putty plug. If you are careful, you can hold the tiny drill bit between your thumb and forefinger and hand-twist it through, but if you have access to a power drill, or even better yet a drill press, you can work much more quickly and accurately.
You can make yourself a little jig to hold the casings upright under the drill by simply drilling a series of 3/8 inch diameter holes in a small, thick block of wood. Stand the casings, puttied end up, in the holes in the block, mount your 7/64 inch drill bit in your drill press, and go to work. Work carefully, and try to keep each hole well centered. The more accurately each hole is drilled, the more accurately each rocket will fly.
As we stated in the beginning, these little rockets are core-burners. You make a core-burner by packing the propellant down around a dowel or mandrel, it leaves behind a hollow core. It's that simple, and the mandrel we use for these tiny rockets is one of the six penny finishing nails that you bought (or better yet, a short length of 3/32 inch diameter piano wire).
The cores or bore-holes in these little motors should be about 11/4 inch long. The core starts at the inside edge of the nozzle plug and extends forward to the inside edge of the forward bulkhead plug. The nozzle plug of 1/4 of an inch thick, so the entire madrel should be 1+1/2 inches long.
To make a mandrel, use a tack hammer (or any small hammer) to pound one of the nails into a block of wood. Then use a pair of dikes or wire cutters to snip it off to a length of exactly 1+1/2 inches. If you're using piano wire instead of a nail, drill a 3/32 inch diameter hole in the block, roughen up one end of the wire with sandpaper or file, and glue the roughened end of the wire in the block with the epoxy glue that you bought. When the glue in completely hard, grind the wire to length with a grinding wheel.
We decided that it would be nice to be able to load a dozen or so rockets at once and proceed with each of the final steps in groups of twelve, so we made one block of wood with twelve mandrel wires on it, each one exactly 1+1/2 inches tall. To use it simply set each drilled rocket casing over one of the wires, drilled end down, and you're ready to start loading.
Now comes the tricky part. To load the sugar based rocket propellant, you must pack it down around the wire coring mandrels, so the tamp that you use must have a hole drilled right in its center and deeper than the length of the mandrel wire inside the paper casing. You make such a tamp as follows. Cut a 4 inch length of 1/4 inch hardwood dowel, sand the ends square, stand it upright under the drill press, and drill a 1/8 inch diameter hole right down the center of the dowel to a depth of 1+1/2inches. If you can find a piece of 1/4 inch brass or aluminum rod, you can make yourself a much nicer and more durable tamp. DO NOT USE STEEL! Since your coring mandrels are made of steel, there is a slight chance (albeit a small one) of generating a spark should the tamp and mandrel strike one another during the loading procedd. Brass against steel and aluminum against steel will, in most cases, not spark, and we consider either of these to be safer to use.
If you're having trouble figuring out just how to accomplish this task, try making yourself a little jig, similar to the one you used to hold the casings upright, to hold the 1/4 unch dowel upright under the drill. If you have access to a machine lathe, or course the job is a piece of cake. Anyone with a lathe can finish it for you in about five minutes.
Next make yourslef a tiny paper funnel, place it over one of the open rocket casings, and fill it with about 1/8 teaspoon of sugar based propellant. Using a small wire or stick, poke enough down into the casing to fill it about half full, remove the funnel, and insert the dowel tamp you just made (drilled end down) into the end of the casing. Using a small hammer, pack the propellant down around the wire mandrel with four or five good, solid hits.
Remove the tamp and add another dose of rocket propellant. Reinsert the tamp and pack this second dose in tightly. Remove the tamp again, and look down into the end of the rocket casing. Keep filling and tamping in the manner described above until the tamped powder just reaches the top of the wire coring mandrel. Now wad up a small piece of kleenex tissue, or paper towel, and pound it in on top of the powder. This kleenex plug keeps the epoxy glue used to plug the front of the rocket from running down and sticking to the coring mandrel.
Once the kleenex plug is in place, fill the remainder of the casing with epoxy glue. Whwn we do it, we mix up enough glue for a dozen or so rockets, and use a small stick to droozle the glue down into the open rocket casings. You can use five minute epoxy if you wish, but we advise you to stay away from it. It will gel so fast that you will mos likely waste a large portion of each batch. If you instead use the slow setting variety, you will have enough working time to make use of all of what you've mixed. Once the epoxy has hardened, you can twist and pull each rocket off of its respective mandrel, and you're done!
The nozzles of these tiny rockets are small, the best performance is obtained when the powder along the entire length of the core is ignited all at once. To accomplish this we adopted the following procedure.
Go to the sporting goods store or local gun shop and purchase a can of FFF or FFFF fine black powder. The FFFF is the best. you will be using it in such minute quantities, that one pound can will last virtually forever (a one pound can is enough to ignite about 2000 if these rockets).
To prime or fuse one of these rockets stand it on end, nozzle up, and using a small paper trough fill the entire core hole right up to the top with the black powder you just bought. It takes an amazingly small amount to do this, and if you were to weigh it out, you would find that you'd used about 0.2 grams. To make a trough take a small peice of paper and make a fold in it that goes to one corner this makes a very sharp pointy trough, the powder will slide down easy
Obviously if you turn the rocket over at this point, all the priming powder will fall out, so you must cap it to keep the powder in. You do this in the following way. Place a small amount of the powder into a baby food jar or something similar, and add water a few drops at a time, stirring with a spoon or a stick as you go, until the mixture is about the consistency of toothpaste. Next take up a small dab of this black powder paste on the tip of your finger, and smear it over the nozzle hole of the rocket that you just primed. Be sure to completely cover the hole, set the rocket aside, and allow this powder-paste cap tp dry for a half-an-hour or so.
This dried black powder cap will seal the core hole, keeping in the loose priming powder, and at the same time will act as an igniter. All you need to do to fire the rocket is to touch this cap with a burning fuse or an electric igniter. The cap will instantly take fire, transfer the fire to the loose priming powder inside the core, and ignite the propellant inside the rocket.
WARNING! Do not attempt to use smokeless nitrocellulose powders. You will just be throwing your money away. Unless they are tightly confined inside a rifle or pistol shell, they will burn so slowly as to be totally useless.
Not all gun shops sell blackpowder. Black powder (especially the FFFF grade) works better than anything else we've tried and it is definitely worth going a little bit out of your way to obtain a can of it. If, however, you can't find it, the Hodgedon Powder Company of Shawnee Mission, Kansas manufactures a fairly good substitute call "Pyrodex". Most gun shops that do not carry black powder do carry Pyrodex. It is a little more expensive than black powder, and it burns a little slower, so your rockets will ignite a little slower, lift-off a little slower, and not go quite as high as they would, had they been primed with real black powder. Pyrodex comes in two grades, coarse for rifles abd fine for pistols. The fine stuff is called Pyrodex P, and this is what you need to ask for.
The easiest way to fly one of these little rockets is to simply glue or tape it onto a stick. If you live near a party shop or a large supermarket that handles Bar-B-Que supplies, you can buy a package of Hibachi Sticks, also known as Shish Kabob Skewers. They're made of bamboo; they're used to skewer small morsels of meat and other cooked foods, and they make perfect guide stcks for your rockets. They are very cheap (less than a penny apiece), and they're flexible, so that if one is a little crooked, it can be easily bent back straight.
You can affix one of them to a rocket with a drop of instant cyanoacrylate model cement/glue), or you can use a drop of white glue and a single wrap of ordinary masking tape. Your rockets will fly a little better if they are slightly streamlined, and you can do this by fashioning a little nose cone out of paper and masking tape and gluing one onto the nose of each rocket. You can buy a piece of cannon fuse (available at gun shops specializing in black powder and muzzle loading supplies), or an electric igniter.
To ignite one of these rockets electrically, the only safe way !
(1) simply tape a filament of wire from a piece of coarse steel wool over the priming cap, attach each end to an electrical lead (Radio Shack sells some tiny little alligator clips that work perfectly), attach the leads to a strong battery, and fire by closing a switch to complete the circuit. The electric current will make the steel wool wire glow red hot, then burn and ignite the priming charge.
(2) You can also use fine Soapless steel wool, just pull a small clump of wool off the pad and twist and stretch it so its about an inch and a half long and about a 1/8 to 1/4 inch thick and tape it to the priming cap and connect the battery leads to each end and close the switch to ignite it
You can launch these rockets from a small tube, the neck of a bottle, or from a soda straw stuck into the ground, and when primed with FFFF black powder and fired vertically, each one will achieve an altitude of 150 to 300 feet. If you wish to see a slow and realistic lift-off, either prime with Pyrodex or don't fill the core all the way to the top with black powder. Put just a little in. The propellant inside the rocket will take fire more gradually, and you will witness a slow lift-off reminiscent of a larger rocket.
Once you've become familiar with these two inch rockets, you can begin to experiment with delay fuses in the front of each motor. A rocket similar to ones you've been making with a time delay added to its front is capable of doing anything that a commercially manufactured model rocket engine can do, including igniting a second stage engine or popping out a parachute.
To advance to this next stage in rocket construction you'll need to buy a few extra items. In order to provide room for a time delay in the front of each rocket, you're going to need a longer rocket casing, and to make a longer casing you'll need to buy some wider brown paper packaging tape. The wider tape is usually not available in supermarkets or stationery stores. It is three inches wide instead of two, and you'll probably have to look in the yellow pages in the phone book and contact a large paper supplier that specializes in packing supplies. It is also usually thicker than the 2 inch material, so instead of needing 8 inches of it, you'll only need about 6. It will cost $5 or $6 for a roll of it, but the rolls are much larger (you get about 10 times as much ).
To construct a rocket with a time delay in front follow all the instructions about for the little two inch rockets with the exception of the following: Use a three inch long casing made from the three inch wide packaging tape, and when you reach the top of the coring mandrel, continue working, using the flat, undrilled end of the tamp, and pack an extra 1/2 inch of propellant in on top of the mandrel. If the time delay seems a little too long, then shorten the delay to perhaps 3/8 of an inch. If it seems too short, then lengthen it to 5/8 or maybe even 3/4 of an inch. You experiment a little bit. With a bit of practice you'll be able to achieve quite consistent results. If you wish, you can make a little depth gauge out of a piece of dowel to tell you when you've reaches the right level.
You'll also need to form a tiny hole or passage-way through the epoxy plug in the front of each rocket, so that the time fuse inside the rocket casing can ignite whatever bursting charge you have in the nose. You do this in the following way. When you're finished packing the propellant into the rocket, stick a large sewing needle into the propellant right at the edge of the rocket casing (not in the middle). Press or tap it into the delay powder to a depth of perhaps 1/8 of an inch. Now firmly pack in your wad of kleenex or paper towel and then pour in the front plug of epoxy.
In this case you have quite a bit of room in the front of each rocket, and you don't need to fill it all the way up. When the glue has thoroughly set and hardened, you can, using a small pair of pliers, twist and pull the needle out of the epoxy, leaving a tiny pin-hole through the plug leading into the time delay powder inside the rocket casing. Larger safety pins work great, because you can use one leg of the pin as a lever and eliminate the need for the pliers during removal.
To make a rocket with a simple report or POP at the end of its flight fill up the tiny hole where the pin was removed with fine black powder or Pyrodex, and then add perhaps another 0.1 of a gram (about half as much as you used to prime the rocket). Now press in another wad of kleenex and pour another epoxy cap on top of that. When the flame inside the rocket reaches the front of the time delay powder, it will flash through the tiny powder-filled pin hole and ignite the powder in the nose, creating in effect, a minature fire cracker and a small puff of smoke in the sky at the end of the rocket's flight.
If you wish to use the time delay to pop a parachute, fill the tiny pin hole with fine powder and add a much smaller amount of powder on top of this. Instead of capping with another epoxy plug, cut a disk of stiff paper from a recipe card, and using one end of your powder tamp, press the paper disk into the nose of the rocket on top of the loose powder mentioned above, sort of like an upside down bottle cap. If you're using the little rocket engine in a small model rocket, the loose powder under the cap will ignite at the end of the time delay. The expanding gases will force out the paper plug, pushing the recovery wadding and the model's parachute out ahead of it. If this doesn't seem clear to you, we suggest that you go to a hobby shop and purchase a small model rocket kit with engines. Go ahead and put it together and fly it a few times. Then you will realize what we are talking about and how much money you can save by using these little homemade rocket motors.
The amount of powder needed to pop out a parachute is incredibly small; perhaps 0.02 to 0.04 grams. Be careful, because if you put in too much, it will tear the shock cord and the parachute right out of the front of your model! Just the tiniest 'pinch is all that is required.
If you wish to have your rocket ignite a second stagem then do as follows. Immediately upon removing the needle or safety pin from the front of the epoxy plug, use a single edged razor blade to cut the excess length of casing off right at the front of the front plug. Then fill the tiny pin hole with loose powder and cap the front of the rocket with the powder paste just as you did to the rear end when priming it for firing. Be sure to mark the front of the rocket, as once the ends are capped, you won't be able to tell which end is which.
When you want to ignite a second stage, simply place the priming cap of the second stage engine in contact or close proximity with the front end cap of the booster or first stage motor. When the flame in the first stage motor reaches the front of the time delay powder, it will ignite the cap at its front, which in turn will light the priming cap of the second stage engine.
When making a two stage stick rocket, you'll need a longer stick to balance the extra weight up front and you'll have to connect the two stages in such a manner that the second stage can slide easily away from the first once the first stage is spent. To make this work, wrap a single layer of paper tape around the front of the booster engine, so that the tape is glued to the front of the booster but sticks perhaps 1/2 an inch out in front of the finished, capped engine. Once the glue is dry, you can slide the tail of the second stage into this paper sleeve at the front of the first until the priming cap of the second stage motor touches the front cap of the first. The fit should be snug, not loose. Glue or tape the longer stick to the second stage engine, leaving the first stage engine and its sleeving free.
When the first stage motor is spent and ignites the second stage rocket, second stage ignition will blow the first away, sending the paper sleeve with it.
Use a shorter time delay for your booster motors than you use for your upper or single stage rockets. The delay should be in the range of 1+1/2 seconds. Once again, experiment a bit to achieve the right performance. If you can't find durham's rock hard water putty, you can make a suitable substitute by mixing regular white baking flour with epoxy glue to the consistency of stiff bread dough.
For two stage rocket motors you need plenty of power to lift the extra weight of the second stage. You can make a more powerful propellant by trying to obtain more finely powered versions of the required chemicals. Flowers of sulfur found at the drug store is actually fairly coarse. You can obtain a more finely powdered form of sulfur by going to a nursery or fertilizer supplier and asking for a small bag of dusting sulfur. The powdered sugar at the supermarket is obviously ideal, but the potassium nitrate that you got at the drug store is also obviously not. About the consistency of table salt, it is too coarsely ground to allow you to make a really fast burning propellant. You can't grind in up in a blender. It will simply pile up and stick to the sides of the container, but if you have or know someone who owns a rock tumbler, used by hobbiests to polish small gemstones, you can render it to an extremely fine state by placing a measured amount into the tumbler along with a few dozen glass marbles and running them together for several hours. As the marbles roll aver one another they will grind the nitrate to a fine powder. You can also grind it by hand but takes a while to do so, use this powder along will dusting sulfur and follow the instructions at the beginning of this report, and your efforts will result in a rocket propellant of superior qualities.
You can also adjust your rocket's performance by either lengthening or shortening the coring mandrels and thereby deeping or shortening the propellant cores, adding more or less propellant respectively to a given rocket. If your rockets fly a little poorly and you can't seem to make a stronger propellant, then make a longer coring mandrel and a deeper propellant core with a little more rocket propellant, and you should notice a distinct improvement. If they explode like firecrackers or blow out their ends, then shorten the mandrel, make the propellant core, itself shorter and use less propellant accordingly.
As always, please follow all local, state and federal fire and safety regulations, and be sure to consider the health and safety of yourself, everyone around you, and their property. If you set a fire with one of these rockets or injure yourself or someone else in the process of making one, it will reflect badly on the hobbies of model and amateur rocketry as a whole and may result in even more repressive legislation than already exists.
The propellant described in this report is very benign when compared to most. However it is a rocket propellant, and as such is capable of causing property damage or serious injury if mishandled or handled carlessly. Be a good representative of your hobby, and please be safe!
[TIP note -- Well, these guys did put in a fair amount of work to write up the 11 page manual above. So, I am leaving in the following crass commercial announcement as my way of thanking them for doing the above. I am not associated with "Teleflite" and have never seen the book advertised below. In fact, they may have moved out of the address given, so it might be a good idea to send a letter WITHOUT a check to find out if they still exist. By the way, they are not being fully truthfull when they claim to be the "only publishing company in the world that offers solid, reliable, and thoroughly proven instruction on the making of homemade rockets and rocket engines." Hopefully I will have a listing of such books in the bibliography section soon.]
The Teleflite Corporation is the only publishing company in the world that offers solid, reliable, and thoroughly proven instruction on the making of homemade rockets and rocket engines. If you enjoyed making and flying the rockets described in this publication and want to learn how to make much larger and more powerful rockets, we suggest that you order a copy of our complete 148 page rocket engine manual, titled BUILDING YOUR OWN ROCKET MOTORS.
As in this report, the techniques involved, although of necessity a little more elaborate, are basically simple. Tooling is cheap and easy to make, and the materials are all inexpensive and readily available to you in your own locality. Once you've ordered the book, you need buy nothing else form us.
BUILDING YOUR OWN ROCKET MOTORS provides fully illustrated instructions for preparing a much more powerful rocket propellant, and it provides complete instructions and plans for making eighteen different rockets varying in size from a tiny A3 that generates 4 pounds of thrust to a giant G100, which when ready to fly, will generate about 70 pounds of thrust! Cost to make them? $0.50 to $0.75 each.
Amateur rocketry is a fascinating hobby. Don't stop now! Keep on learning! If you wish to order a copy of BUILDING YOUR OWN ROCKET MOTORS, send a check or money order for $21.95 to: Building your own rocket motors, The Teleflite Corporation, 11620 Kitching Street, CA 92388. California residents add 6% state sales tax. Foreign countries except Canada add $2.00 for shipping and handling.