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