The differences include the following:
- Composite propellant has up to 3 times the power of black powder by weight
- Composite propellant model rocket motors are usually “core burning” and are ignited at the “head end” of the propellant grain instead of the nozzle end
- A reinforced plastic case is used in a composite model rocket motor instead of a wound paper case
- The composite model rocket motor nozzle is reinforced plastic instead of pressed clay
- The bulkhead end of the composite model rocket motor is cast epoxy or molded plastic
- Composite model rocket motors are much louder and more spectacular than black powder model rocket motors
- Rockets powered by composite model rocket motors will fly much higher and faster than with black powder model rocket motors
- The high energy of composite propellant enables the manufacture of model rocket motors that are the same size as black powder model rocket motors but with about twice the power.
Will AeroTech 18mm "D" and 24mm "E" and "F" model rocket motors fit in my model rockets that are built for Estes or Quest black powder model rocket motors?
Yes, AeroTech 18mm "D" and 24mm "E" and "F" composite model rocket motors are the same physical size as black powder "C", "D" and "E" model rocket motors.
How are AeroTech model rocket motors ignited?
AeroTech single use model rocket motors are ignited with a 2-wire initiator similar to that used in black powder model rocket motors. They can be ignited using the same electrical launch controllers used for black powder model rocket motors too. AeroTech reloadable model rocket motors are ignited using the AeroTech “Copperhead” initiator which requires a special clip and a 12 volt launch system. In either case the initiator must be placed at the top of the propellant core space, rather than just inside the nozzle as with black powder model rocket motors.
What do I need to get started?
For the ‘D’ and ‘E’ single use model rocket motors, you only need the model rockets you already have and a desire to see them fly higher, faster and louder than ever before! If you want to fly reloadable model rocket motors, you’ll need the reloadable model rocket motor hardware, matching model rocket reload kits, a Copperhead clip and a 12-volt launch system.
What groups or associations do I need to join?
You do not need to join any group to fly model rocket motors up to ‘G’ class, but the National Association of Rocketry (NAR) and the Tripoli Rocketry Association (TRA) provide numerous valuable services to their members. You can learn more about these organizations by visiting their websites at www.nar.org and www.tripoli.org.
What is the difference between black powder and composite propellant?
Black powder is a pressed mixture of Potassium Nitrate, Sulfur and charcoal. This propellant has been used for hundreds of years but has relatively low performance. In contrast, composite propellant is usually composed of a mixture of Ammonium Perchlorate, synthetic rubber and a metal fuel like Aluminum. Its performance can be up to three times that of black powder by weight, and because of this it is commonly used in all sorts of military rockets and the Space Shuttle solid rocket boosters (SRBs). It has other important advantages, too.
What are common user errors with composite propellant model rocket motors?
Common user errors include failure to insert the initiator completely into the propellant core space, dropping a single use model rocket motor, improper assembly of reloadable model rocket motors, using the wrong initiator clip or launch controller, choosing the wrong time delay for the model rocket being flown.
How do I find out if there is an organized rocket launch coming up in my area?
The National Association of Rocketry maintains a launch calendar at http://www.nar.org/NARcalend.shtml. Launch announcements are also published in popular rocketry magazines such as Sport Rocketry and Rockets.
Do composite propellant model rocket motors ever fail? How do they fail?
Occasionally (usually less than 1% of the time) a composite model rocket motor will fail. The most common failure mode of a single-use motor is a case failure, where the casing will split into two or more pieces upon ignition, usually caused by a defect in the case itself. Most of the time the propellant will extinguish itself when this happens! Other modes may include a low-pressure ignition due to improper initiator installation and, rarely, ejection charge failure. For reloadable motors, the most common failure mode is a burn-through of the forward closure, usually as a result of improper motor assembly.