If you are old enough to remember the old Oldsmobile advertising campaign, "These are not your grandfather's black powder rockets."
This newer version of the charcoal-tailed rocket motor is commonly called the "nozzleless motor," but I call 'em "speed rockets" and you'll soon see why.
Nozzleless motors are a recent development which has distinct advantages over some other motors:
- They're dirt simple to build. All you need is fuel, tooling and a tube. Simple hand-ramming works fine and a motor can be made quickly - in about 3 minutes.
- These motors can lift a hefty payload - up to 2.5 ounces for the 1/2-inch ID motors you'll see here. Commercial festival-ball shells can be used as expedient rocket headings, or a quick bag-shell heading can lift a load of test-stars high into the air to evaluate their performance.
- The fuel for these motors is not dusty to use at all and does not require ball milling.
- The rammed motors are easier than most to remove from the spindle, because of the lubricant in the fuel,
- These motors are very difficult to blow up ("CATO") at launch. Successful flights are easy with these motors.
- Coarse charcoal can be added to the fuel for a golden spark tail.
- Titanium particles can be added to the fuel above the spindle/core to create a silver-spark tail.
- Although ball-milling the fuel is not necessary for successful flights, it can be used to create "hotter" fuel that provides more thrust than simply-screened fuel will produce.
I made 10 of these rockets, motors and headings in a couple hours one afternoon. That made for a nice rocket display that evening.
Completed 1/2-Inch Speed-Rockets, Ready for Launch
Nozzleless black powder rockets with charcoal and titanium tails and red star headings.
History of the Nozzleless Rocket Motor
Traditionally, black powder rocket motors are made with a clay nozzle that the hot gasses are forced through to create thrust. These are called "nozzled" motors.
The first time that many of us heard of "nozzleless motors" they were associated with a rocketeer named Donald Josar--"DJ" to those who knew him.
I asked doc barr (a well-known and respected US rocket man, who lives so deep in the hinterlands that they have not discovered capital letters yet) for a little history concerning DJ.
"i knew dj probably as well as anyone.The most recent successes I've been seeing with nozzleless motors at pyro events were rockets built by my friend Dan Thames. It was those flights which recently inspired me to play with nozzleless motors more than I had in the past. I asked Dan about his inspiration for the motors.
i used to stay with him in the days prior to the wwb [ed.note: Western Winter Blast - a major pyro event held every February by the Western Pyrotechnic Association], and talked him into going.
i wrote his obituary in afn..
a hell of a guy!
he posted a letter with an attachment showing his 3/4-inch rocket taking up 1 lb of water......... i must have been the only one to see it so i wrote and told him what a phenomenon it was....... that's how we got started.
original............ he didn't know anyone that did rockets.
he just couldn't keep a nozzle in them so he said, 'screw it, i'll make one without a nozzle.' "
I joined R-BP about the time (about 2000) I started trying to make BP rockets. In several posts DJ kept saying, 'If you have problems with your BP Rockets, just leave the clay out.' He also said to use fast fuel. My first three blew the top bulkhead out and I left the clay out and they started flying. Then I paid a lot of attention to DJ and let him tutor me.So, you can see that the nozzleless motor, at least in its current form, is a modern version of the black powder rocket--one which many folks have not even heard of.
What I recall is he got the idea of a Nozzleless BP and several experienced rocket guys scoffed at the idea. He tried to talk it up and get input but very few supported him. I think Doc Barr did and encouraged him to try.
By the time I made my first PGI convention in 2006, DJ had died about a year or so before. Maybe it was just months, I don't recall. I came to the PGI to compete and all I did in competition was to ram a pair of 6lb nozzleless for Best Large Rocket Motor. In the description I wrote, 'In honor of Donald Josar, inventor of the nozzleless BP rocket, a pair of 6lb hand-rammed Nozzleless Black Powder Rockets,' or something very close to those words. The next year Doc Barr looked me up and we talked about the rockets and DJ. He was very pleased to see someone trying to carry on DJs efforts.
I always remember, "If it don't work, just leave the clay out." A good rule of thumb :)"
Cross-Section of a 1/2-Inch Black-Powder Nozzleless Rocket Motor
Rocket Tooling and TubesWe'll be using standard, 1/2" black powder core-burner rocket motor tooling in this project. The paper tubes that are used with this tooling are 1/2-inch ID, 5-inch long, parallel wound tubes.
Skylighter's 4-ounce black powder core burner rocket tooling.
The rammers come with the red and green lines etched into them at the appropriate places (except I add a green line on the solid rammer). The red lines are "do not pass" marks. The rammers are never to be rammed into a motor tube past those marks. This is to ensure that the rammer does not come into contact with the spindle. That would potentially "pinch" the fuel at the contact point and might ignite the fuel during ramming, which would make for a Very Bad Day.
The green lines on rammers #1 and #2 are "switch rammer" marks. When they are even with (or above) the top of the tube after ramming a fuel increment, they indicate that it's time to switch to the next rammer.
I have added a green line on the solid rammer (#3) 1/2-inch above the bottom of that rammer to indicate when enough fuel has been rammed in the motor. I will see that mark even with (or above) the top of the tube when enough fuel has been rammed. Draw that green line on your solid rammer, 1/2-inch from the bottom.
A very helpful tip for making doubly sure that the rammers are never rammed into the tube past the "do not pass" marks is to apply a thick wrap of masking tape to each of the rammers so that the bottom edge of the tape is even with the red lines. These thick wraps of tape will prevent the rammer from going further when the do-not-pass mark gets to the top of the motor tube.
Thick Masking-Tape Wraps on Rammers
Making the Rocket Fuel - Getting StartedSafety Note: The process of making and using the rocket fuel can be dusty. And the lacquer thinner used in reducing the dust produces noxious and flammable fumes as it evaporates. Wearing a respirator rated for paint fumes and performing these steps outdoors will minimize the impact of the dust and fumes.
Please read and observe these safety instructions. These essays detail important safety precautions for mixing compositions, and for making and storing fireworks devices.
The most important safety precautions are:
- Minimize the amount of exposed pyrotechnic compositions and devices at all times
- Wear safety glasses
- Wear cotton clothing that covers as much of the body as possible
- Safely store compositions and devices.
To that formula we add a small amount of mineral oil as a lubricant. That this is in addition to the basic formula is indicated by the "+" sign in the percent and factor columns. Finally, the 1/4 cup of lacquer thinner is required to dissolve the mineral oil for easier incorporation into the fuel. After the fuel is dried, the lacquer thinner will have entirely evaporated leaving only the oil behind in the fuel.
|Component||Percent||Factor||4 oz||113.6 g|
|Potassium nitrate||75%||0.75||3 oz||85.2 g|
|Airfloat charcoal||15%||0.15||0.6 oz||17.05 g|
|Sulfur||10%||0.1||0.4 oz||11.35 g|
|Mineral oil||+2%||+0.02||0.08 oz||2.25 g|
|Lacquer thinner||1/4 cup|
We will also be discussing several optional modifications to this fuel mixture which will permit you to add variety to your rockets by altering both their performance and appearance in the sky. Here are some additional chemicals we will need for these modified fuel formulations.
|Charcoal, 80-mesh||+5%||+0.05||0.2 oz||5.7 g|
|Fine spherical titanium||+10%||+0.1||0.4 oz||11.35 g|
We will use materials to make three variations of the fuel.
- Using only the Basic formula, the most powerful fuel can be made. This fuel will lift the heaviest headings possible. But the Basic fuel will not leave a pretty spark-tail behind the rocket.
- A pretty, long-lasting, charcoal-spark tail can be added to the rocket motor's display by adding 80-mesh charcoal to the Basic formula, This will enhance the rocket's appearance during nighttime flights and reduce the motor's thrust only slightly.
- Or adding spherical titanium to the fuel creates a bright silver spark-trail behind the rocket as it ascends.
These motors, even with the coarse 80-mesh charcoal in them, will easily lift headings weighing between 1.5 and 2.5 ounces. So, if you do want the pretty nighttime charcoal tail, I'd recommend adding that coarse 80-mesh charcoal to your fuel.
If you want the silver spark tail in your rockets, use the titanium additive, but only in the fuel that is rammed above the spindle. The fuel rammed above the spindle accounts for about 20% of all the fuel in the motor. So, you'll want about 80% of your fuel to not contain the titanium and about 20% of your fuel to contain it.
Let's say you want to make 30 rockets. Each batch of the Basic fuel, shown in the formula table above, yields about 6 motors. So, you need 5 batches to make 30 rockets.
For the 30 rockets you would make 4 batches with the Basic formula, and add only 80-mesh charcoal to it.
Then you would make a fifth batch with the Basic formula with 80-mesh charcoal and titanium added to it.
You'll end up with 80% of your fuel NOT containing titanium, which you ram around your spindle. You ram the 20% of your fuel containing titanium above the spindle to create the silver tail.
The processes for making the Basic fuel and the amounts of oil and lacquer thinner are all the same for any of the fuel variations. Simply add the additional coarse charcoal and/or titanium during the final mixing stage, as explained in the next steps.
For your first nozzleless rockets, I suggest you make up a batch of the fuel containing just the additional 80-mesh charcoal, and experiment with making some motors just to get the hang of it. Then you can make a batch of the titanium-containing fuel later to play with the silver spark tails.
Making the Rocket Fuel - Tools and Supplies RequiredThese items will be needed as you make the rocket fuel:
- A printout of the formula and the following instructions
- The chemicals: potassium nitrate, airfloat charcoal, sulfur, 80-mesh charcoal, spherical titanium, mineral oil from a grocery or drug store, lacquer thinner from the paint department of a hardware store.
- A spoon or scoop for measuring chemicals
- A 1/4-cup measuring cup
- A blade-type mill: coffee grinder or single-serving blender, or
- A ball mill (optional)
- A 100-mesh screen (not needed if ball mill is used)
- A 20-mesh screen
- A digital weighing scale
- Paper cups
- A wood stirring stick, such as a popsicle stick or tongue depressor
- A sheet of paper larger than the screen(s)
- A small paint brush
- Rubber gloves (the paint stripping kind, able to withstand lacquer thinner)
- A respirator
- A plastic mixing tub and tight-fitting lid
The tools and supplies you'll need to make black powder rockets.
Making the Rocket Fuel - Milling, Mixing and ProcessingHere are two different ways to pulverize and intimately mix the chemicals: ball milling or blade milling.
If you will be using a ball mill, simply weigh out the potassium nitrate, airfloat charcoal, and sulfur, put them in the ball mill and mill them together for two hours, using the safety procedures described here:
Ball Milling Media Cautions
For successful ball milling, see this article,
Quick & Easy Black Powder Ball Mill,
See the section called "Loading and running the ball mill optimally."
If you are using the small ball mill shown in that article, do not use any dextrin in the mix, and use the amounts of potassium nitrate, airfloat charcoal, and sulfur shown in the formula table above in this project. Do not mill the 80-mesh charcoal or titanium.
If you are using a larger, a one-gallon capacity ball mill, that jar will mill 20 ounces at a time. So you should multiply amounts of potassium nitrate, airfloat charcoal, and sulfur shown in the table above by five. Weigh them out, and add them to the one gallon jar for milling.
Properly handling your ball milled black powder rocket fuel.
Ball milling both pulverizes and intimately mixes the chemicals. This eliminates several steps that are necessary if you use the blade-milling and screening process described next.
If you will not be using a ball mill, the potassium nitrate must first be milled with a blade mill to ensure that it is a fine, talc-like consistency. It must be fine enough to pass through a 100-mesh screen. The airfloat charcoal and sulfur are usually already milled finely enough, although the sulfur may have soft clumps in it. Those clumps will break up easily when you push it through the 100-mesh screen.
Milling potassium nitrate in a coffee grinder and screening it to make sure it is fine enough to use for hand mixed black powder.
Measure out about 1/2-cup of the potassium nitrate. Put it in a blade-type coffee mill or a single serving blender like the one shown above currently available at Walmart for less than $20.
SAFETY NOTE: use blade-type grinders only on individual chemicals, never on mixtures of chemicals. If you're using a blade mill to mill different chemicals, be sure to clean the mill out thoroughly between each different chemical.
Put the potassium nitrate in the grinder and grind it for three minutes. Then place the 100-mesh screen on a large sheet of paper and dump the milled chemical onto it. With your gloved hand, work as much of the potassium nitrate through the screen as possible.
Weighing out the potassium nitrate, sulfur and charcoal to make black powder rocket fuel.
Weigh three ounces of the milled and screened potassium nitrate into a paper cup. Then dump that chemical into the empty mixing tub.
Dump the potassium nitrate that wouldn't pass through the screen onto the paper, and back into its tub for future use.
Weigh out 0.6 ounces of airfloat charcoal. Put it into the mixing tub. Repeat with 0.4 ounces of sulfur, unless you need to screen the clumps out of it.
Cap the mixing tub tightly and shake it, holding the lid securely on the tub as you do so.
Screen mixing black powder chemicals with a 100-mesh screen.
Put the 100-mesh screen back on the paper. Gently pour the black powder mixture onto the screen. Work the powder gently through the screen with your gloved hand.
Put the screened mixture back into the mixing tub. Shake it well, holding the lid on securely as you do.
Repeat the screening and shaking process two more times, for a total of three screenings of the complete base mix.
Adding additional charcoal or titanium to black powder rocket fuel.
If you want to add a charcoal and/or titanium tail, weigh the additional ingredient(s). Then add them to the mixing tub with the base mix, cap, and shake thoroughly.
Adding Mineral Oil and Lacquer Thinner to Fuel to Create a "Putty Ball"
You now have a very fine, and intimately mixed, batch of rocket fuel. If you used it at this point, as-is, the fuel would be too dusty to work with, and would not compact into a very solid fuel grain. So you solve those two problems in this final step: You granulate your rocket fuel with the mineral oil and lacquer thinner.
Note: Always work with lacquer thinner outdoors. Wear a respirator because the fumes are noxious and extremely flammable.
Weigh (using your scale) out the oil into a clean paper cup on your scale.
Measure out (using a measuring cup) the 1/4-cup of lacquer thinner and add it to the oil. Stir the oil and thinner together with the wood stirring stick.
Pour the liquid mixture into the dry fuel powder mix in its tub. Then knead the liquid into the powder with your gloved hand. Create a nice solid "putty ball."
Granulating wet black powder rocket fuel with a 20-mesh screen.
Now crumble the ball of fuel between your fingers onto the sheet of paper. Remake the ball with your hand. Repeat, over and over, until the putty becomes thick and crumbly. This doesn't take long because the lacquer thinner evaporates so quickly.
Once again, do this outdoors so the fumes will dissipate safely. Be sure and wear a respirator so you don't breathe those fumes.
Once the putty is thick and crumbly, put the fuel back into the plastic tub. Put the 20-mesh screen onto the sheet of paper, and work the fuel through the screen with your gloved hand to create 20-mesh granules of fuel.
Spread the fuel granules out evenly. Dry them on the paper in a safe, outdoor, warm, dry, breezy location for a few hours until you no longer smell evaporating thinner.
Put the dry fuel into a tightly sealed storage container in a safe place.
Ramming Motors - Materials Required
Supplies you'll need to hand ram black powder rocket fuel.
For this step, you'll need:
- 1/2-inch ID, 5-inch-long paper tube
- The rocket-tooling set
- A funnel which fits into the paper tube
- A 1/4-teaspoon measuring scoop
- The dried rocket fuel
- A shallow container for the fuel we will be working from
- A solid mallet
- A solid post on which to do the ramming
- A leather glove for the hand which will be holding the tube as the fuel is rammed
- Safety glasses
Ramming the Motors - Procedure
You will be ramming rounded 1/4-teaspoonful increments of fuel into the paper tube. Ideally, each solid rammed increment of fuel should end up being between 1/4-inch and 3/8-inch tall.
Only ram fuel with no titanium in it around the spindle. Ram titanium-bearing fuel only after the rammed rocket fuel is above the tip of the spindle.
Open the tub of fuel and scoop about 1/4-cup of it out with the shallow cup. Reseal the tub and set it aside. Make sure there are no other exposed compositions or devices in the work area.
This is a very important safety step. Minimize the amount of openly exposed ignitable materials so you limit what could be ignited if an accident occurred.
If your tooling has been used before, see if the holes in rammers #1 and #2 are free of fuel. Clean any fuel out of those holes with a bamboo skewer or a drill bit. Keep them free of fuel during the ramming process.
This is critical. You do not want fuel building up inside those holes and possibly getting "pinched" between the top-inside of the hole and the tip of the spindle. Pinching causes accidental rocket explosions.
Wear a leather glove to protect the hand you're using to steady the paper tube and the spindle as you're ramming fuel. Wear safety glasses whenever working with combustibles.
Place the paper tube over the spindle and seat it squarely onto the spindle base. Looking down into the tube, make sure the tip of the spindle is centered in the paper tube.
Verifying that the Spindle is Centered in Tube
How to safely hand ram black powder rocket fuel to make a nozzleless rocket.
Load a rounded 1/4-teaspoonful of the fuel into the tube through the funnel. Insert the long hollow rammer #1 into the tube, and push it in by hand as far as you can. The do-not-pass mark should be about1/2-inch above the top of the tube before you start ramming that first increment of fuel.
If you need to add a little more fuel to this first increment to keep that do-not-pass line at (or above) the correct 1/2" height before ramming, do so now. Then ram that fuel increment with eight nice solid whacks of the mallet. You should feel the fuel start to get nice and solid at about whack #4 or #5. The rammer should stop going much farther into the tube with the final few whacks.
Ramming the First Increment of Fuel
The goal is to ram the fuel nice and solidly compacted, without splitting the paper tube. If you loaded enough fuel into the tube, the do-not-pass line will not go into the tube. If it looks like the do-not-pass line will be rammed into the tube, stop and add a little more fuel. Then finish ramming that increment.
After the first increment of fuel has been solidly rammed, remove the rammer from the tube. Verify the tip of the spindle is still centered in the tube. Gently push the tube one way or the other to center that spindle in there. This is important so that the second rammer does not contact the spindle when it is used. This will also prevent your spindle from getting bent.
Ram another rounded 1/4-teaspoonful of fuel the same as the first one. Repeat the ramming of increments until the green switch-rammer line on rammer #1 is visible above the top of the tube after an increment has been rammed.
Clean any excess fuel out of rammer #1 and set it aside. Start ramming fuel increments with rammer #2 in the same manner. Ram those increments until the switch-rammer mark becomes visible on rammer #2 (after a rammed increment). Then clean out the hole in that rammer and set it aside.
If fuel containing titanium is to be rammed above the spindle, switch to that fuel now. Put all the non-titanium fuel away in its tightly closed tub.
Ram increments of fuel with the solid rammer until the green end-of-fuel line is visible after the final increment. Tap any excess fuel out of the top of the motor back into the cup of fuel from which it came, and put the fuel away in a safe location.
The motor can be twisted off the spindle now. The top of the motor should reveal a nice, solid fuel grain, recessed down into the tube 1/2-inch. The bottom end should show a nice, solid, shiny fuel grain with the hollow core going up into it.
Top and Bottom of Fuel Grain in Finished Rocket Motor
These rocket motors, of course, can be flown as-is, with no heading to display at the end of their flight. If you want to see if your motors are flying well before installing any headings, just skip down to the next step of "Installing the Stick...".
Installing a Heading on the Rocket MotorEventually, you will probably want to have a "heading" display as the motor burns out at apogee. Headings may be as simple as a single large star, up through larger bag-shell headings, homemade cylinder-shell headings, or homemade or commercial festival ball-shell headings. Any of these can be added to your motors.
These motors will lift headings weighing up through 2.5 ounces when they've been made correctly.
Here's how to use a commercial 1.4g festival-ball aerial shell as a heading:
Remove the green fuse, lift cup, and lift powder from a festival ball (or "reloadable" or "artillery shell"). You'll see a primed time fuse projecting from its bottom. Measure 1/8 teaspoonful of loose rocket fuel and put it into the empty space at the top of your motor. Then insert the shell's time fuse into the space at the top end of the motor. Seat the shell against the top of the motor tube and then tape or hot-glue the shell to the rocket motor, observing hot glue safety precautions.
These small rockets are excellent for testing new stars designed to be used in large aerial shells. They will send a test-star high into the air, igniting it up where you plan to see it. You can see the star perform under realistic conditions: at a distance, traveling through the air, and high in the sky.
You can install that single test star very easily. The rocket tool spindle makes a nice stand for the motors during this process.
Single-Star Heading Secured with Masking Tape
Materials Needed to Install a Simple, Single-Star Heading on the Rocket Motor
Put 1/8-teaspoonful of the loose rocket fuel into the empty top end of the finished motor tube. Place the star to be tested on top of the motor and that loose fuel, and use two strips of masking tape to hold it in place and fireproof it. When the rocket fuel burns through the top of the solid fuel grain the star will ignite and you'll see it up where you want it.
Loose Fuel and Star atop Rocket Motor
Installing the Stick on the Rocket Motor - Purpose of the StickThese rockets are stick-stabilized. That means a simple stick is used to keep the rocket going in the direction you want at launch and during flight.
Installing the Stick on the Rocket Motor - Materials
Materials for Installing Stick on Rocket Motor
Materials needed in this step:
- Rocket motor
- 1/4-inch-square, 18-inch-long stick for rocket with no heading or a very light one. Use a longer stick for a rocket with a heavier heading.
- 1-inch-wide masking tape
- Razor-anvil cutters to cut the stick (or a different cutting tool)
Installing the Stick on the Rocket Motor - ProcessHome Depot, Lowes, and similar hardware/lumber stores sell 1/4-inch-square, 36-inch long "square dowels" in the lumber/molding department. For rockets with no headings or light ones, you can cut one of these in half to make two 18-inch rocket sticks. If your rocket has a heavier heading, use a longer stick.
Find the center of the stick by balancing it on a finger. Cut the stick in half diagonally, as shown in the photo above.
Lap the stick onto the nozzle-end of the rocket motor with at least 2-inches of the beveled stick lapped onto the motor.
Holding the Rocket Stick on the Nozzle End of the Rocket Motor
Tear off 8-inches of the masking tape and tape the stick onto the motor. Add a second masking-tape band, as shown in the photo below.
Two Masking Tape Bands Holding Stick onto Motor
Sight down the motor and stick, and twist the stick side-to-side to align it parallel with the motor for a straight rocket flight.
Sighting and Aligning Rocket Stick and Motor
Installing the Ignition Fuse in the Rocket Motor - MaterialsMaterials needed in this step:
- Green Visco ignition fuse
- Razor cutter to cut fuse; never use scissors to cut fuse
- Rocket motor with stick attached
Installing the Ignition Fuse in the Rocket Motor
Ignition Fuse Cut, and Installed in Rocket Motor
Cut a 4-inch length of Visco fuse with a razor blade, or razor-anvil cutters. Bend 1/2-inch of the fuse doubled back in itself, and insert that doubled end about 1 inch into the core in the fuel of the motor. The fuse will be held securely in place by the doubled part of it.
Cut a 4-inch length of Visco fuse with a razor blade, or razor-anvil cutters. Bend 1/2-inch of the fuse doubled back in itself, and insert that doubled end about 1 inch into the core in the fuel of the motor. The fuse will be held securely in place by the doubled part of it.
If one or two rockets have been made, and they will be taken out and flown immediately, they are now ready to go.
If several rockets have been made, and will be handled and/or stored, and then taken out and flown as part of a display, let's say, then it's a good idea to enclose and cover the exposed black powder fused end of the rocket motors. That exposed fuel can take fire from errant sparks very easily, and installing a "nosing" on the fused end of the rocket motor before the stick is installed will prevent that from happening.
Simple nosings can consist of a couple wraps of wide masking tape or aluminum foil tape, bunched around the fuse, or a glued and tied strip of paper long enough to wrap twice around the motor tube.
Nosing Installed on Rocket Motor
Flying the Rocket
For this final, fun step of the rocket process, all you need is:
- The finished rocket
- A launch tube about 3-feet long
- A source of ignition, such as a Bernzomatic TS4000 propane torch (you'll burn your thumb if you light Visco fuse with a cigarette lighter or a match)
Rocket Inserted into Launch Tube, and Being Ignited