Hacker News new | past | comments | ask | show | jobs | submit login
SpaceX – Pad abort test successful (livestream.com)
24 points by outworlder on May 6, 2015 | hide | past | favorite | 12 comments



From the video, it looked good. Great takeoff, boost, coast and landing. Really well done!

https://www.youtube.com/watch?v=5bhW2h08zhY

Couple of points of interest: There were a couple of puffs of smoke from the engines that might be a sign of premature shutdown. Having one engine out would cause uneven thrust which will cause the vehicle to rotate or tumble. The test continued successfully, so if an engine did indeed die, we can assume that another was also intentionally shutdown to balance the thrust. The remaining engines would have fired for a little longer to make up for the lost ones.

The engine chambers are the first entirely 3d printed production rocket motors in the world. They're printed in inconel using Direct Metal Laser Sintering. This is the first time that so many of them have been fired in an actual mission scenario. The tech is so new and untested that special shields were built round the motors to isolate the rest of the vehicle in case of an explosion. I'm very interested to see how they held up.

There was some pretty severe tumbling during the drogue and main chute deploys. While easily survivable, this would have been quite uncomfortable for any passengers inside. I wouldn't be surprised if SpaceX tweaked the deployment sequence a little to help reduce this.

Good job, SpaceX... I can't wait for the In-Flight abort test later this year!


i thought i remembered, and so confirmed(i), that the super dracos were positioned in pairs and run at half thrust each

a precaution against a possible failure

in the event of a failure the others will increase thrust to compensate:

if your analysis is correct, i'd speculate further at a possible intentional shutdown to test the super draco's buddy system

(i) https://www.youtube.com/watch?v=zLdhhPGLntk#t=10m17s


> they're printed in inconel using Direct Metal Laser Sintering.

As someone who works with people who occasionally have to machine this stuff, that's seriously impressive.


What are the comparative advantages of Direct Metal Laser Sintering vs the more traditional CNC Milling?

CNC Milling

- Broader base of manufacturers who can meet specs

- Lower cost?

- Higher strength?

- Faster essential steps (prototyping can be done more rapidly)

3D Printing

- More optimal alloy distribution since the part is built up instead of milled down

- Less raw materials used / lower waste

fixermark suggests: - Can machine shapes that are impossible to machine via reductive process.


I don't know for certain if it mattered in this specific case, but the 3D Printing list should include

- Can machine shapes that are impossible to machine via reductive process.

... (sort of, if you turn your head and squint. "Without seams" ;) ).


CNC milling does have more metal waste up front, but it's usually recovered, separated from any contaminants, and remelted into new metal, so it's not really "waste" in the long-term sense. The recovery isn't free, of course, but then that's just another part of the economics calculation.


What blows me away is comparing the acceleration of a fully loaded Falcon 9 and today's test. Obviously, the two are different and you know the acceleration will be different to escape a failure of the rocket.

But to see something so small with relatively little fuel on board, take off so fast is really incredible.


Another great step for SpaceX. At the moment it feels like they're making progress every other week.

What sort of G loads do the astronauts in that capsule experience in an abort scenario? It shoots up much faster than a typical launch. The separation from the trunk looks fairly violent too.


> At the moment it feels like they're making progress every other week.

And they intend to accelerate their schedule as they go! This is so exciting!


4-5 Gs.


Anybody know why they don't leave the trunk behind in the first place? It seems like a waste of fuel.


The trunks mass moves the COG rearwards and when combined with the fins, it provides passive stability that keeps the nose pointing in the direction of travel.

Notice that when the trunk detaches, the craft immediately starts pitching over.




Consider applying for YC's Summer 2025 batch! Applications are open till May 13

Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: