First of all, this is THE
First of all, this is THE MOST DANGEROUS project for anyone to do. MOST DANGEROUS project for anyone to do. ItIt should not be attempted in any manor unless you have significant experience should not be attempted in any manor unless you have significant experience
with making rocket motors of this size. Manufacturing flaws can cause with making rocket motors of this size. Manufacturing flaws can cause extremely violent and powerful failures in the structure of this motor, which extremely violent and powerful failures in the structure of this motor, which can lead to property damage, personal injury or even death. I therefore, release can lead to property damage, personal injury or even death. I therefore, release
myself of all responsibility with what you do with this page. Please exercise myself of all responsibility with what you do with this page. Please exercise
every possible safety precaution if you do decide to proceed. every possible safety precaution if you do decide to proceed.
What You'll Need What You'll Need
Casing Of Rocket
Casing Of Rocket
1. 1 Length of 1" (dia.) schedule 40 PVC pipe (hardware store; 1. 1 Length of 1" (dia.) schedule 40 PVC pipe (hardware store; schedule 40 is standard)
schedule 40 is standard)
2.1 PVC Male threaded reducing coupler 1" (hardware store; 2.1 PVC Male threaded reducing coupler 1" (hardware store; looks like the picture below)
looks like the picture below)
3. 1 PVC end cap 1" (hardware store) 3. 1 PVC end cap 1" (hardware store)
4. 1 can of standard PVC cement (hardware store) 4. 1 can of standard PVC cement (hardware store)
5. 1 can of standard PVC purple primer (hardware store) 5. 1 can of standard PVC purple primer (hardware store)
6. 1 can of Durham's Rock Hard Water Putty (comes in different 6. 1 can of Durham's Rock Hard Water Putty (comes in different amounts; pick amount depending on how many of these you plan amounts; pick amount depending on how many of these you plan to make) (hardware store)
to make) (hardware store)
7. Scrap piece [or small sheet] of 1/4" PVC (plastic supply) 7. Scrap piece [or small sheet] of 1/4" PVC (plastic supply)
Propellant and Casting Equipment
Propellant and Casting Equipment
1. 78 g Potassium Nitrate (
1. 78 g Potassium Nitrate (KNO3) (Chemical Supply)KNO3) (Chemical Supply) 2. 42 g Confectioners sugar
2. 42 g Confectioners sugar
3. Small (about one cup) metal pan 3. Small (about one cup) metal pan 4. Larger metal pan
4. Larger metal pan
5. 6"x 1/2" Wood Dowel 5. 6"x 1/2" Wood Dowel 6. Automotive Grease 6. Automotive Grease 7. Stick for stirring 7. Stick for stirring
8. Shortening (I used Crisco) 8. Shortening (I used Crisco)
9. Old coffee grinder, or something similar 9. Old coffee grinder, or something similar 10. Stove or hotplate
10. Stove or hotplate Procedure
Actual Photo of Engine Actual Photo of Engine
1. Cut a small disk out of the 1/4" 1. Cut a small disk out of the 1/4" PVC sheet/piece to the exact inside PVC sheet/piece to the exact inside diameter of the "nozzle" on the PVC diameter of the "nozzle" on the PVC male reducer coupling (should be male reducer coupling (should be 3/4").
3/4").
2. Using the purple primer and PVC 2. Using the purple primer and PVC cement, cement the disk into the cement, cement the disk into the inside of the nozzle right where the inside of the nozzle right where the reduced part meets the main part of reduced part meets the main part of the coupler. (Labeled PVC Holding the coupler. (Labeled PVC Holding Insert in the drawing the left). Allow Insert in the drawing the left). Allow to dry.
to dry.
3. Mix Durham's Rock hard Water 3. Mix Durham's Rock hard Water Putty with water until it is the
Putty with water until it is the consistency of loose mayonnaise. consistency of loose mayonnaise. Pour enough in the wide end of the Pour enough in the wide end of the male reducer coupling to fill if about male reducer coupling to fill if about half of the way from the cemented half of the way from the cemented PVC insert to the wide end of the PVC insert to the wide end of the coupling (see drawing). Allow this to coupling (see drawing). Allow this to dry for a minimum of 48 hours.
dry for a minimum of 48 hours. 4. Drill a 9/32" (.713cm) hole 4. Drill a 9/32" (.713cm) hole
through the PVC holding insert, and through the PVC holding insert, and all the way through the water putty. all the way through the water putty. This is the throat of the engine. This is the throat of the engine.
5. Cut a piece approximately 5" long 5. Cut a piece approximately 5" long from your 1" PVC pipe. The exact from your 1" PVC pipe. The exact length isn't important, as you will length isn't important, as you will trim it to exact size later.
trim it to exact size later.
6. Measure out 78g of KNO3 and 6. Measure out 78g of KNO3 and 42g of Sugar (65% :35% FYI). The 42g of Sugar (65% :35% FYI). The KNO3 you bought is probably not KNO3 you bought is probably not fine enough for these purposes. This fine enough for these purposes. This is what the coffee grinder is for. Put is what the coffee grinder is for. Put the KNO3 in the old coffee grinder the KNO3 in the old coffee grinder and
Nozzle section Nozzle section
Propellant Grain Propellant Grain
possible. Now pour the KNO3, and possible. Now pour the KNO3, and the sugar into a small Tupperware the sugar into a small Tupperware container and shake for several container and shake for several minutes to thoroughly mix the two. minutes to thoroughly mix the two. Note that they should never be Note that they should never be
ground together in the coffee ground together in the coffee grinder!!
grinder!!
7. Widdle the end of your dowel to a 7. Widdle the end of your dowel to a point. Then coat the hole thing in a point. Then coat the hole thing in a very thin coat of automotive grease. very thin coat of automotive grease. 8. Put enough shortening in your big 8. Put enough shortening in your big pan to fill it up about half way when pan to fill it up about half way when
melted. Heat the shortening up to melted. Heat the shortening up to between 350 and 400 degrees F and between 350 and 400 degrees F and
then place your smaller pan in the then place your smaller pan in the bath with some of the propellant bath with some of the propellant
(enough to fill it up about half way (enough to fill it up about half way in powder form) in it. Stir
in powder form) in it. Stir
continuously and don't let the small continuously and don't let the small pan touch the bottom of the big pan. pan touch the bottom of the big pan. The propellant should start to melt. The propellant should start to melt. As it does, pour more in, until it is As it does, pour more in, until it is all melted. I have had several e-mails all melted. I have had several e-mails about the melting process. You want about the melting process. You want to melt it without caremeling it. This to melt it without caremeling it. This means stirring continuously and not means stirring continuously and not letting the melted propellant get any letting the melted propellant get any darker than a kind of yellow color. darker than a kind of yellow color. IT SHOULD NOT BE
IT SHOULD NOT BE BROWN!!BROWN!! 9. The propellant should be about the 9. The propellant should be about the consistency of honey, or a little
consistency of honey, or a little thinner. Put your 1" PVC pipe thinner. Put your 1" PVC pipe
section on a piece of wax paper and section on a piece of wax paper and pour the melted propellant into the pour the melted propellant into the pipe.
pipe.
10. Immediately put the dowel 10. Immediately put the dowel through the middle of your melted through the middle of your melted
External View of Propellant Grain
External View of Propellant Grain propellant. It should slide through propellant. It should slide through easily. Wait about 10-15minutes and easily. Wait about 10-15minutes and pull the dowel out. It might be
pull the dowel out. It might be
difficult, but it should slide out. Let difficult, but it should slide out. Let the propellant cool for about 30 more the propellant cool for about 30 more minutes. Store it in an airtight bag in minutes. Store it in an airtight bag in the freezer.
the freezer.
11. Using a handsaw, saw off the 11. Using a handsaw, saw off the end of the pipe that isn't full of end of the pipe that isn't full of propellant so that both ends are flat. propellant so that both ends are flat.
12. Using your purple primer and 12. Using your purple primer and PVC Cement, cement the propellant PVC Cement, cement the propellant section into the nozzle section (the section into the nozzle section (the male reducer coupler) and then cap male reducer coupler) and then cap the other end off with the end cap in the other end off with the end cap in the same manner.
the same manner.
13. Let the cement dry for about 24 13. Let the cement dry for about 24 hours (just to be sure) and your hours (just to be sure) and your ready to go.
ready to go.
Congratulations! You have just built a low end "G" engine! This Congratulations! You have just built a low end "G" engine! This
thing is extremely powerful for it's size and can do extensive thing is extremely powerful for it's size and can do extensive injury/damage if it fails. So please, static fire this motor well away injury/damage if it fails. So please, static fire this motor well away
from people, property or other liabilities and secure it properly from people, property or other liabilities and secure it properly when you do so. This motor has a maximum thrust of over 50lb when you do so. This motor has a maximum thrust of over 50lb and as such will go RIGHT THROUGH you if it is freed in your and as such will go RIGHT THROUGH you if it is freed in your
direction while firing. Be careful out there. direction while firing. Be careful out there.
I have designed this motor to be as safe as possible. I have not had I have designed this motor to be as safe as possible. I have not had
a single failure of the casing-although I have had several nozzle a single failure of the casing-although I have had several nozzle ejections while trying new things. If you build exactly according ejections while trying new things. If you build exactly according to these instructions, you should find it very reliable. The nozzle to these instructions, you should find it very reliable. The nozzle will blow at pressures well below that which the PVC casing will, will blow at pressures well below that which the PVC casing will, and as such is an effective safety margin. But with this in mind, and as such is an effective safety margin. But with this in mind, make sure that the ejection of the nozzle will not endanger anyone make sure that the ejection of the nozzle will not endanger anyone
or anything in the case that it does. Good luck and be careful!! or anything in the case that it does. Good luck and be careful!!
