Overview
One of the most challenging aspects of a multistage rocket launch is lighting the second stage reliably at near vacuum pressures. Overall system performance is strongly sensitive to second stage ignition timing and many, many, many vehicles have failed to light their second stage. A head end ignition system is designed to be controlled by the sustainer avionics system and reliably and rapidly pressurize the sustainer motor, raise the propellant to it's ignition temperature, and be highly robust to premature ignition.
| Year | Lead |
|---|---|
| Spring 2019 | Sam A. |
Design
38mm COTS Blue Thunder grain installed in forward closure ~80Ns
...
This system was placed on a 3 in motor. The casing for the HEI (the unlabeled black thing outside the HEI grain) is 1/8th inch phenolic. It is easy to crack. In this case, the o ring grooves cannot be even slightly over the diameter listed in the Parker O ring guide. This will result in snapping the casing. It is also difficult to cut. We use a miter saw and found that the best method is to go slowly and have lots of extra stock because it cannot handle shear stresses well.
Pictures
Tests
| Test | Location | Date | Notes |
|---|---|---|---|
| HEI Only Test | Bldg. 37 Blast Chamber | April 2019 | Success! |
| Friends of Amateur Rocketry | July 6, 2019 | Very Successful! | |
| HEI Only Test | Bldg. 37 Blast Chamber | July 2022 | Failure - loss of pressure |
| Static Fire | Crow Island Airfield | July 2022 | Failure - loss of pressure |
| HEI Only Tests | Bldg. 37 Blast Chamber | September- October 2022 | Mostly successes, some struggles with ignition |
| Static Fire | Crow Island Airfield | October 2022 | Success! |