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"Wooden chair" seems like a rather drastic oversimplification. Yeah, the bulk of the device, and its combustible material, is made of wood. But it's also got t
by bunderbunder 8y ago
"Wooden chair" seems like a rather drastic oversimplification.
Yeah, the bulk of the device, and its combustible material, is made of wood. But it's also got two igniters (for redundancy) and a sensor for ensuring that the device has successfully ignited. Some engineering thought went into this. Comparing it to putting a burning piece of furniture under the rocket nozzles makes the whole design sound a lot more jerry-rigged than it really is.
- Xylakant 8y agoNotably, the ignition device, while seemingly low tech, works pretty much without flaws and fails safely. “This setup is not as simple as a regular match, but it is surprisingly reliable and has worked for six decades on hundreds of rockets” So why attempt to fix such a safety critical thing?
- petschge 8y agoThe one reason to go from external match sticks to internal ignition using hypergolic fuels is to be able to relight in flight after an engine shutdown.
- bunderbunder 8y agoYep. Which seems like a fairly unnecessary requirement for an expendable first stage. I'm no rocket engineer, but my guess would be that, if you're shutting down an engine at that stage in the flight, your only realistic options are going to be redirecting fuel to the remaining engines for a longer burn, or cutting all engines and activating the launch escape system. I can't imagine there's any practical reason to plan on shutting down and re-igniting engines during the first stage of a launch, and I also can't imagine trying to decide whether an engine is safe to re-light during the few seconds you'll have between when you executed the emergency shutdown and when it's time to jettison the first stage entirely.