| A reloadable motor is a motor designed | | | | cardboard liner. The propellant grains |
| to be used multiple time by inserting | | | | are inserted into the liner. The delay |
| new propellant and replacing other | | | | grain is ignited when the motor ignites |
| expendable components. A reloadable | | | | and burns slowly. When it burns through, |
| motor usually consists of an aluminum | | | | the motor ejection charge, if used, is |
| tube (a special aluminum alloy) and | | | | ignited. When the recovery system is |
| closures to hold the nozzle on one end | | | | deployed through motor ejection, black |
| and to seal the other end. Some | | | | powder is installed in the forward |
| manufacturers have the closures screw | | | | closure's "ejection well". The delay |
| into the motor case. Others use other | | | | grain goes inside the forward closure. |
| techniques to secure the closures, like | | | | APS motor forward closure APS Forward |
| a snap ring. | | | | Closure |
| Pictured is a Dr. Rocket/Aerotech | | | | This is the forward (top) closure, |
| reloadable motor. On the left is the aft | | | | showing the ejection charge well. |
| closure, which closes the rear of the | | | | Black powder is placed into the well, |
| motor and holds in the nozzle, the motor | | | | and cover with some masking tape to hold |
| case and on the right the forward (top) | | | | it in, when motor ejection is used to |
| closure. (Dr. Rocket is a licensed | | | | deploy the parachute. A small hole is in |
| manufacturer of Aerotech's motor | | | | the bottom of the well so that the black |
| technology.) | | | | powder is in contact with the top of the |
| The aft closure is slightly larger than | | | | delay grain. When the delay grain burns |
| the case. When the motor is inserted | | | | through the black powder is ignited. |
| into the motor mount tube the lip keeps | | | | When an electronic mechanism, such as |
| the motor from moving up through the | | | | altimeter, is used to activate the |
| motor mount tube and rocket when | | | | ejection charge, a plugged forward |
| thrusting. | | | | closure may be used if offered by the |
| Motor cases are available in different | | | | motor manufacturer. A plugged closure is |
| diameters and lengths to allow for | | | | like the pictured one but the top is |
| propellant kits of different size and | | | | solid, having no ejection well or hole. |
| total energy. | | | | APS delay installed |
| A propellant reload kit contains one or | | | | This picture shows an APS forward |
| more propellant grains, and other | | | | closure with the delay grain inserted |
| components that are replaced each time | | | | into its chamber. |
| the motor is used. Most motors use one | | | | The motor must be ignited from the top, |
| or more silicone O-rings that must be | | | | not near the nozzle. The igniter must be |
| replaced each time the motor is used. | | | | fully inserted into the motor. |
| Some manufacturers use a plastic nozzle | | | | Motors must be cleaned between uses. |
| that must be replaced for each motor | | | | Insufficient cleaning, or reusing old |
| use. Others use a graphite nozzle that | | | | parts can result in hot gas leakage and |
| is usually good for about 20 flights | | | | motor and rocket destruction. Motors can |
| before replacement is needed. | | | | be field cleaned using foil wrapped, |
| AeroTech RMS™ Reload Kit H123 Reload | | | | wetted towels which are sold under |
| Kit | | | | several brand names in grocery and other |
| AeroTech/Dr. Rocket | | | | stores. |
| This is an AeroTech reloadable motor | | | | The silicone O-rings must have a light |
| reload kit, which can be used with | | | | coat of lubricant ("grease") applied to |
| either an AeroTech RMS™ or Dr. Rocket | | | | them when they are installed. The |
| reloadable motor. | | | | lubricant allows the closures to slide |
| This particular kit, an H-123, contains | | | | over the rings without crimping or |
| two individual propellant grains, a | | | | tearing them when the closures are |
| cardboard motor case liner, rubber | | | | installed and tightened. Following the |
| O-rings, a single-use plastic nozzle, a | | | | manufacturer's instructions. The O-rings |
| delay grain and components, and assorted | | | | should have only a light coating - just |
| seals. | | | | enought to give them a sheen. Too much |
| The propellant grains are inserted into | | | | lubricant can result in motor failure. |
| the liner, and the liner is then | | | | Too much lubricant on O-rings near the |
| inserted into the motor case. | | | | forward closure, where the ejection |
| APS reloadable motor showing components | | | | delay grain is located, can result in |
| APS Motor | | | | failure of the delay grain to ignite if |
| Advanced Propulsion Systems | | | | the lubricant gets on the faces of the |
| Shown here is an Advanced Propulsion | | | | grain. (Dirty hands can also cause the |
| Systems (APS) reloadable motor. The | | | | delay grain to become contaminated with |
| motor consists of a case, forward | | | | lubricant.) If the delay grain fails to |
| closure, aft closure (next to the | | | | burn and motor ejection is used to |
| nozzle) and graphite nozzle. The nozzle | | | | deploy the recovery system the rocket |
| can be used for about 20 flights before | | | | will crash and crumple, hopefully not |
| replacement. | | | | damaging any person or other property. |
| APS reloadable motor reload kit APS | | | | The particular type of lubricant used |
| Reload | | | | (petroleum jelly, grease with Teflon, |
| An APS reloadable motor reload kit is | | | | etc.) is not nearly as important as the |
| shown here. It contains an O-ring, three | | | | correct application of the lubricant. |
| propellant grains, a delay grain, and a | | | | |