SpaceX plans ocean platform landing

[c041v]

I'm wondering if they could develop some sort of industrial strength 'Velcro' or barbs on the landing leg pads that would hook into the deck as it lands. You could just unbolt the pads to free the stage and grind off the barbs.

Maybe a big electromagnet on the barge!?

I'm blown away by the whole thing. Elon and the SpaceX team have given me hope that all the things I read in Popular Mechanics might actually happen someday. I can only imagine how inspiring this must be for the generations in grade school.

 

[Stoneymonster]

I'm wondering if they could develop some sort of industrial strength 'Velcro' or barbs on the landing leg pads that would hook into the deck as it lands. You could just unbolt the pads to free the stage and grind off the barbs.

Maybe a big electromagnet on the barge!?

Heh.

 

[ecarfan]

The video of the landing is fascinating. I watched it at least 10 times. I think if the clip that was posted on vine had started a bit earlier it would have shown that the rocket's vertical axis was oscillating slightly and the onboard computer was over correcting. But just slightly.

So close! Next time Elon...

 

[voidptr]

As another poster, Grendal, noted earlier they should aim for zero velocity at say 25 ft above ground and then inch it down. Sure takes more fuel.

You can't do that with the current Merlin engines, they don't throttle down enough. The one engine they use on the landing burn throttled down as low as it will go still has more thrust than the empty first stage weighs, so they have to do a hover slam to decelerate to zero just as the rocket touches the deck. If they decelerate to zero higher, they can't hover or slow controlled descent, the engine would start accelerating it back up.

 

[Krugerrand]

A little spray of WD40 should clear that right up!

And duct tape. (Surely there's a use for it, no?)

 

[Cosmacelf]

Elon twitted that they think the control problem was related to "valve stiction" This caused the crazy rocket angles due to control lag. Sez easy problem to fix

Good stuff. It did indeed look like the control was lagging. If it is something mechanical like valves, should be relatively easy to fix.

 

[Norbert]

Hmm... well it actually seems nearly zero out the vertical by the time it reaches the barge, so that may be by design to minimize fuel consumption.

I agree. The programming seems to be focused on using as little fuel as possible. Under those circumstances it seems to be trying to bring a lot of variables together right at the moment of landing. If there was any extra fuel then use a little more to bring more variables in synch prior to the last moment would make the whole thing a lot easier.

To me it looks like it might have gotten everything down to zero, except the sideways movement of the bottom of the rocket. The top seems to rest. Maybe the problems with the valve kept it from stopping the sideways movement at the bottom, in time.

 

[Lerxt]

Yes that sideways vector at the end is what did it. It was looking so good up until the last 50'

 

[chickensevil]

Elon twitted that they think the control problem was related to "valve stiction" This caused the crazy rocket angles due to control lag. Sez easy problem to fix

Did he remove this tweet? Because I don't see this comment anymore? Maybe removed because that wasn't the actual problem?

Either way, I am super pumped for the next landing attempt.

- - - Updated - - -

What is required by the Government to allow an attempt on land?

I think the comments from the Air Force was that they would *prefer* they land successfully on a barge first. I hadn't seen anything set in stone either direction. SpaceX has already gotten a contract to build a landing pad from one of the old launch complexes at the Cape. Completing this construction will likely take a year or so anyway. If by the time the pad is complete *and* we don't have a successful barge landing, then it might become more of a battle from SpaceX to allow clearance to attempt a ground based landing attempt.

But keep in mind that between now and the end of the year, SpaceX is going to have quite a few more landing attempts on the ocean. The next 4 launches are all LEO, so unless either the angle is too crazy or the payload is too heavy we should get landing attempts on the next four launches.

So if they can stick even just 1 water landing, I think the Air Force will be satisfied because it should be super easy at that point to stick a shore landing after overcoming all the difficulties of the ocean.

 

[Robert.Boston]

That video is going to become a classic "early days of 21st century space flight" moment. Think of those great video clips of interesting plane designs not quite working. I now see why this is a drone ship; you couldn't pay people enough to be aboard. The scale of the Falcon 9 and the ship are very different than I had been thinking (i.e., the rocket is much bigger than I had imagined, or the landing pad much smaller).

 

[scaesare]

I don't like the video... The pic was great.

Looks to me like rocket rate of decent was way too fast. I was expecting just lateral issues. Wind etc.

With each attempt they are getting closer. They fail in new ways, which means they corrected the previous issue.

Darn impressive... and clearly just a matter of time.

That volcano lair will be Elon's before you know it.

 

[hockeythug]

Remember they swapped launches with the one next week so the next launch won't have landing legs.

 

[Electroman]

You can't do that with the current Merlin engines, they don't throttle down enough. The one engine they use on the landing burn throttled down as low as it will go still has more thrust than the empty first stage weighs, so they have to do a hover slam to decelerate to zero just as the rocket touches the deck. If they decelerate to zero higher, they can't hover or slow controlled descent, the engine would start accelerating it back up.

Don't know about the Merlin engines, but the couple of demos that SpaceX published in YouTube seems to have a no problem hovering at 1000 feet and coming down slowly.

 

[ThosEM]

[vine]euEpIVegiIx[/vine]

Is it just me or does it appear to others that it landed in the water? Why else would all that steaming spray be kicked up? Better video is promised and will tell the tale.

This doesn't look as well controlled as the practice landings on terra firma. I suspect there is insufficient fuel for a more leisurely and comfortable approach so they are hurrying things as fast as possible and exceeding the capabilities of the current control system.

 

[Stoneymonster]

Is it just me or does it appear to others that it landed in the water? Why else would all that steaming spray be kicked up? Better video is promised and will tell the tale.

This doesn't look as well controlled as the practice landings on terra firma. I suspect there is insufficient fuel for a more leisurely and comfortable approach so they are hurrying things as fast as possible and exceeding the capabilities of the current control system.

If you saw the frames taken from the platform, it's clear it is pretty much on target.

 

[Martini]

Yes, exactly. Softer landing=more fuel so they have to bring it in hot. No margin for error.

 

[Johan]

The goal is likely to have something like 1% fuel or less remaining after landing. To bring extra fuel all the way up and then down again, that'd be like burning money. Every pound brought up costs plenty $$$.

 

[ggr]

Yes, exactly. Softer landing=more fuel so they have to bring it in hot. No margin for error.

Sorry, no. The problem is that the Merlin engine can't be throttled LOW enough to hover or fall; its minimum thrust is greater than the weight of the nearly empty rocket. They measure the amount of fuel/oxidizer very accurately, so they could have more fuel in it at the end if they chose to, but that has various costs: it's more explosive when it arrives; taking that fuel up costs even more fuel; it still doesn't overcome the actual problem.

 

[mknox]

What strikes me as odd is that I thought the touchdown was the "easy" part. They've been doing this with their Grasshopper and Falcon 9 test vehicles in Texas for some time now. I thought the hard part would be turning that sucker around at the edge of space, decelerating from high supersonic speeds and actually finding and hitting the landing site. They seem to be nailing that aspect of it.

 

[haid]

is there a possibility of grabbing the thing using some contraption at the last second, to neutralize the tipping problem ?

The mad scientist in me wants to see four posts quickly telescope up 2/3 the height of Falcon. Once extended, each post has a snare that slips off the other posts and tightens around the rocket.