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I wasn't sure if the ascent looked OK - no idea if it was supposed to be running on two, then one engine. But that was a moment that I'll remember for the rest
by djaychela 6y ago
I wasn't sure if the ascent looked OK - no idea if it was supposed to be running on two, then one engine. But that was a moment that I'll remember for the rest of my life. Amazing stuff, even with what obviously meant the complete demise of SN8.
I'm sure they'll learn an immense amount from it, and it was amazing to see it nearly pull off the landing. Given the way that Falcon 9 early landing attempts went, it'll go the same way with Starship, and it'll be landing soon.
- enraged_camel 6y ago>>I wasn't sure if the ascent looked OK - no idea if it was supposed to be running on two, then one engine. I realized that this may have been done to slow down the acceleration to make sure it doesn't go past the 12 km limit. I may be wrong though.
- endymi0n 6y agoI also wasn't entirely sure whether the engine shutoffs were fully intended... at least the sideways acceleration of the Raptors at shutoff looked scary.
- Kye 6y agoWe don't usually see rocket engines cut off in that much atmosphere, but it's probably normal.
- apendleton 6y agoAs engines shut off, the remaining ones that were still going had to rapidly re-center to keep the direction of thrust aligned with the center of mass of the vehicle, and the ones that had shut off had to move out of their way to make room.
- codeulike 6y agoI think it was hovering for a while at the top of the ascent.
- grishka 6y ago> no idea if it was supposed to be running on two, then one engine Yeah and then something caught fire near the engines. I expected it to explode that very moment.
- Filligree 6y agoI think that was the ignition system; the green flame matches. Which makes sense if they lost an engine, of course.
- remarkEon 6y agoWhat's the reason that the flame produced by the ignition system is green? Edit: ah, it's answered here https://news.ycombinator.com/item?id=25366736 https://news.ycombinator.com/item?id=25366736
- elteto 6y agoThat’s incorrect. Raptor does not use a TEA/TEB igniter like Falcon. It uses a spark igniter. The green flame here is unintended engine ablation :) The chamber was melting.
- ArPDent 6y agospecifically it's copper being vaporized i believe
- remarkEon 6y agoNice. Flashbacks to highschool chemistry. I'm assuming this isn't something you want to have happen ...
- SAI_Peregrinus 6y agoNo, engine-rich combustion cycles are definitely not something you usually want. Especially not on a re-usable craft.
- codeulike 6y agoI'm wondering if the engine shutoffs on the way up were deliberate, so they could get data on running on 3,2 and then 1 engine.
- qayxc 6y agoThey looked planned. I think they tested the full array of required operations: shutdown, gimbal, throttling, re-ignition.
- wongarsu 6y agoEven in normal operation it might have been useful to throttle down the engines in order to ascend a bit slower (less drag). If you have multiple engines, shutting some of them down is a convinient way to throttle.
- seg_lol 6y agoIt was a wonderfully designed test. I'd love to hear a presentation on test design, the mission profile and what data they were looking at with each one. I assume SpaceX has the same video feed with superimposed telemetry. I'd love to know turbo pump pressure and rpm during landing.
- smiley1437 6y agoIf you look at the timer, it's almost certainly planned Engine 1 cuts off 1m45s after launch Engine 2 cuts off 1m28s after engine 1 Engine 3 cuts off 1m28s after engine 2 and then SN8 goes into glide testing. The extra time on all 3 engines is probably to gain sufficient height?