SpaceX Falcon 9 : Hispasat 30W-6 (1F) : March 6, 2018 - DISCUSSION

[Nomadd]

 The hawser would probably be the limit. Towing at that speed would put ridiculous loads on it as the barge bounced around and they usually use that for a weak link.

[Jcc]

Any chance they could make the trajectory more lofted and add boost back to allow recovery nearer to shore? Just putting it out there.

[Pete]

Any chance they could make the trajectory more lofted and add boost back to allow recovery nearer to shore? Just putting it out there.

Altered trajectory is reasonably doable, but incurs a non-trivial performance penalty.
Considering the speculation about just how SpaceX is managing to even attempt recovery on this launch (partial block 5, etc...), I seriously doubt there is performance margin left to play with.

P.S.
I'm no rocket scientist, nor am I a sailor.
But to my amateur eye, this picture looks scary:

[kevinof]

I am a sailor - Depends on when the data was taken and what speed it's moving away at (I assume it's moving North East).  If it's replaced with higher pressure (usually is) then the sea will settle down quite quick. All depends on the speed and timings.

[LouScheffer]

There is no way Hawk is getting into position in a day. End of story.

Nerd me a story why it can't be done.

*Could* it be done; quite possibly.  A nuclear powered aircraft carrier would do the trick, if the cables and their anchorages would hold, and the resultant pounding did not destroy the barge.

But trying to tow anything at even twice normal speed is normally a no-go.  You need 4 times the force and 8 times the power, roughly.  Here's an example:  lots of people pull a trailer behind their car/truck, at 110 km/hr (70 mph), even in non-deal conditions.  That's exactly what normal equipment is designed for.   But twice that speed is the world record, set only with a highly modified truck on a dead flat course in ideal conditions for a short amount of time.

So it may be possible, but it's surely not practical.

[RocketLover0119]

Heck. Titanium fins are on the s1 still?

[cscott]

Just wrapping up the fast-tow discussion -- I was never advocating for Xtreme X-Tow SpaceX Xdition. At the time I wrote my OP it was still within a few hours of the "expected " departure time (or at least as I understood it, without having crunched the numbers myself) so I was just suggesting that we might see "what Hawk is capable of" with an as-fast-as-possible tow... which I figured would be only a bit faster than usual.  Still would have been interesting as a minimum-time-to-station benchmark, and so worth paying attention to.

Of course, OCISLY still hasn't left port, so we probably won't get to see that max-speed tow this time (for whatever reasonable value max-speed actually has).

My assumption is that foresight and planning don't usually result in a scramble to position.  This case was sort of a fortuitous natural experiment because the sea state improves so quickly after a nor'easter passes that it made sense to get OCISLY in position as late as possible (again, for reasonable definitions of possible).

[TorenAltair]

Heck. Titanium fins are on the s1 still?

Perhaps they don't want to change their rocket in a way never done before: internal landing hardware and legs but no gridfins. They could just try to water-land it and perhaps salvage the fins then. How fast could a tug be there without pulling a barge?

[jpo234]

They could just try to water-land it and perhaps salvage the fins then. How fast could a tug be there without pulling a barge?

I don't think they can intentionally do this. The F9 is ITAR controlled. Leaving it intentionally salvageable in international waters even for a short time is almost certainly an ITAR violation.

[Rebel44]

They could just try to water-land it and perhaps salvage the fins then. How fast could a tug be there without pulling a barge?

I don't think they can intentionally do this. The F9 is ITAR controlled. Leaving it intentionally salvageable in international waters even for a short time is almost certainly an ITAR violation.

Wrong

Water landings (before SpaceX started attempts to land on ASDS) tried to do exactly that.

[jpo234]

They could just try to water-land it and perhaps salvage the fins then. How fast could a tug be there without pulling a barge?

I don't think they can intentionally do this. The F9 is ITAR controlled. Leaving it intentionally salvageable in international waters even for a short time is almost certainly an ITAR violation.

Wrong

Water landings (before SpaceX started attempts to land on ASDS) tried to do exactly that.

Are you sure? I know about the water landings, but AFAIK there never was an expectation that the booster would survive and could be salvaged. SpaceX was very surprised when the GovSat booster floated in the Atlantic.

[jketch]

Yeah, but they're initial recovery plan was to have parachutes deploy from the first stage to allow it to land gently on the ocean. It proved infeasible to do passive reentry, but they never would have tried it in the first place if it were an ITAR violation.

[RocketLover0119]

They could do an entry burn and burn up the rest of the fuel THEN parachute down and they could safely recover the booster due to no fuel left from the entry burn....

Yeah, but they're initial recovery plan was to have parachutes deploy from the first stage to allow it to land gently on the ocean. It proved infeasible to do passive reentry, but they never would have tried it in the first place if it were an ITAR violation.

[Journeyman]

I can't believe thy decided to not remove the Ti grid fins!

I guess it takes to long to remove the fins and still support the current launch window?

It's almost like you wish there is a scrub today so they can attempt the launch and landing another day when weather is favorable. 

[bsegal]

Wonder if they'll change the mission profile to maximize first stage performance (burn to depletion) and get the payload into a more optimal transfer orbit?

[Nomadd]

Wonder if they'll change the mission profile to maximize first stage performance (burn to depletion) and get the payload into a more optimal transfer orbit?

They aren't going to recover the booster, but they'll probably still bring it down for testing. Just a few feet lower than originally planned. The data from these hot landings (waterings?) is valuable.

 I have to wonder if they'll change policy for the Block 5s, as in delay for weather in the recovery area. They're not going to want to lose those so easily.

[AC in NC]

I can't believe thy decided to not remove the Ti grid fins!

I guess it takes to long to remove the fins and still support the current launch window?

It's almost like you wish there is a scrub today so they can attempt the launch and landing another day when weather is favorable.

It does seem surprising they couldn't squeeze that in but it occurs that if you still plan to charge full-freight then you can't impact the contracted commitment and late changes might do that.

[Spudley]

I know I'm late on board (heh, pun intended) with the discussion about the boats, but I wanted to ask something that I didn't see anyone else mention. Granted, the opportunity for this launch has passed, but I'll ask anyway.

Given that the limiting factor in getting the fleet in place is the speed of OCISLY, I wonder whether they could have left it out there while still returning the rest of the fleet. Obviously they couldn't have left it unattended, but if they'd sent a replacement tug, the original tug and the rest of the fleet could have gone home, and still been able to get back out in time.

Obviously this is all hypothetical now, but the thought occurred to me so I thought I'd ask if it was possible.

[Semmel]

I think they just make lemonade out of the lemons they are served. If they have to ditch the titanium grid fins, why not test them in a maximum reentry flight path? A reentry profile that they would not use if they try to recover the first stage. Maybe go to the extreme and perform no reentry burn. It will probably cook the engines, but it would put the maximum amount of heat on the fins. If they live through that, they know they dont need to worry for any future landings using them. Maybe drive the stage at an insane angle of attack, one where the models might be ambiguous about the stresses on the structure?

Ditching the fins might not be entirely useless or painful.

[gongora]

I know I'm late on board (heh, pun intended) with the discussion about the boats, but I wanted to ask something that I didn't see anyone else mention. Granted, the opportunity for this launch has passed, but I'll ask anyway.

Given that the limiting factor in getting the fleet in place is the speed of OCISLY, I wonder whether they could have left it out there while still returning the rest of the fleet. Obviously they couldn't have left it unattended, but if they'd sent a replacement tug, the original tug and the rest of the fleet could have gone home, and still been able to get back out in time.

Obviously this is all hypothetical now, but the thought occurred to me so I thought I'd ask if it was possible.

The fleet came back in because of the weather.  They wouldn't have wanted to leave the ASDS out in those conditions.