67 Contrail hybrid motors are now Tripoli certified!

Contrail Rockets Hybrid Motor Hardware

Contrail 75mm and 98mm hybrid motor systems consist of three pieces of hardware: the oxidizer tank, the combustion chamber, and the nozzle. All three are connected with hex-head flush mounting bolts. To assemble a Contrail 75mm motor, you select one of three different sizes of oxidizer tank, one of four different sizes of combustion chamber, and one of three different nozzles, and bolt them together.  75mm reload kits come with a fuel grain, a set of fill and vent tubes, an igniter, and a set of injectors that screw into the oxidizer tank. The fuel grain is cast in a paper liner; several different fuel formulas are available. 

Contrail 38mm and 54mm hybrids are monotube motors with an internal injector baffle that separates the fuel grain from the oxidizer compartment. The injector baffle can be in different positions depending on the length of the fuel grain (like the "floating injector" motors made by Ratt Works, Propulsion Polymers and Sky Ripper). There are five different 38mm motor lengths. The forward bulkhead/vent and injector baffle are the same for all 38mm motors (except for the J800, which requires a special high speed injector baffle), and they are all held in place by external snap rings. There are three different nozzles available: slow, medium and fast/x-fast. The injector orifice comes with the reload kit and is not part of the standard hardware set; it is used once and replaced. Two fuel grains are used: solid PVC, and a high regression rate fuel that is cast in a thin PVC liner.

The combinations of different motor casing lengths, different nozzles, different injector sizes, and different fuel formulas makes the Contrail hybrid motors the most flexible hybrid motor hardware available. Contrail Rockets has demonstrated a commitment to certify and produce as many practical motor combinations as possible. This makes the Contrail motor hardware an outstanding value.

You can purchase Contrail hardware in three different ways:

Components are also sold separately. So, for example, if you get the 3200cc 75mm Hardware Set with a Medium combustion chamber nozzle for the L122 load, you can add a Long combustion chamber and Fast nozzle to allow you to use the L2525 and M2281 loads. The 38mm Injector Baffle and Forward Bulkhead are the same across all 38mm motor sizes, so once you have one 38mm Motor Hardware System you can simply add different motor casing lengths to the hardware you already have, and use more motor combinations. 

Details of the Contrail 75mm hybrid motor hardware (98mm and 152mm hardware is similar)

Fuel Grains are available in several different propellant compositions. Since this is a hybrid motor, the fuel grain has no oxidizer mixed with it like conventional solid propellant. It is shippable without hazmat restrictions and does not require special storage.

There are three Nozzles: Slow, Medium and Fast. The nozzle itself is a precision machined piece with a graphite insert; the throat of the graphite insert determines the nozzle speed. The nozzle bolts into the aft of the Combustion Chamber with flush mounted hex head bolts and is sealed with two O-rings. There is a groove just above the bell section of the nozzle for a snap ring that serves as a thrust ring and retention device.

The upper section of the Contrail motor is the Tank Assembly, which incorporates the five-port Injector.

The oxidizer tank vents through the center port of the injector. No extra hole or fitting in the rocket body is required for the vent line. The vent line is secured outside by a special fitting that can be attached to the launch pad in a position where it is easily visible.

Each Reload kit contains a Fuel Grain, a bundle of tubing, an igniter, and five push-to-connect injector fittings. The bundle ("loom") of tubing has four outer tubes and once center tube. The center tube is the vent, and is always 1/8 inch clear tubing. Two of the outer four tubes are looped, and the other two are connected to the fill system to fill the oxidizer tank.

Fast motors use 1/4 inch diameter fill tubing. Medium motors use 3/16 diameter tubing, and Slow motors use 1/8 inch diameter fill tubing. Since the connectors are provided with each reload kit, the injector serves all three speeds.

Contrail reloads are non-pyrotechnic as shipped. They require the addition of Pyrodex pellets as igniter boosters. This allows them to be shipped and stored without regulatory issues.

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