Hacker News Reader

Comment by monkmartinez | Hacker News Reader

I had an in-flight emergency (kind of) today while doing a cross country flight with a friend who is a PPL. We lost the alternator and lucky for us the weather was really good, sans high winds. That means we had no instruments and no comms.... except the back up handheld radio and our cell phones. No harm, no foul and we landed safely...

I say that to say this; I would hope they are just really fast at inspections. There is a real reason to get them right. Failures happen, even to super analog tech.

View on HN

I think its important to note that while you shoot for reusability, if the vehicle fails where it can complete is primary objective (but not return to pad), that's not a show stopper; SpaceX has an entire warehouse full of returned cores now. For ICT, same deal. Hope for the best, but if your core has a critical failure and must burn a bit longer to achieve orbit, thereby losing boostback and sacrificing itself, you start rolling out the next core to the pad as soon as telemetry tells you (if you're on the clock with colonists waiting in orbit for fuel before breaking orbit).

This is not without precedent; a Falcon 9 core previously had a failure of an engine in flight, and the vehicle recalculated the burn time on the fly to continue on with the primary mission.

https://arstechnica.com/science/2012/10/that-smooth-spacex-l...

Ultimately, it may be better to abort in such cases, and land with payload (assuming there's enough propellant left to do so), or even discard the payload. As re-usability becomes more commonplace, the cost of the first stage booster will dwarf the cost per launch, and we'll probably see space launches for increasingly lower value cargo.

The dynamic loads of a fully loaded Falcon 9 preclude an abort once it's off the pad; you are committed.

I'm not an aerospace engineer, but if one wants to comment, I'd be happy to be corrected. It already requires ideal conditions for stages to separate successfully.

I realise this comment is now over a week old, but could you clarify what you meant? I don't know the specifics of the Falcon 9, but the only tolerance problem I see is in the strength of the landing legs, supporting the weight of the payload when landed (any excess propellants can be burnt off). Obviously you could make them bigger at the cost of lift mass.

The weight distribution of a fully fueled and payload-carrying Falcon 9 prohibits it from attempting any sort of boostback burn back to the landing pad if an abort is needed. It would tear the vehicle apart.

It would be similar to a a fully loaded semi truck trying to turn on a dime.

Reply on news.ycombinator.com