Space Things

[Spuds]

The ocean is a pretty big net though. Parachutes like that are neither accurate nor precise.

[Dadhawk]

Originally Posted by Spuds

The ocean is a pretty big net though. Parachutes like that are neither accurate nor precise.

Are those stages buoyant enough to float?

Personally, I think SpaceX has the right idea, and have proved it's a viable solution with direct fueled landings.

[Ultramaroon]

The SRBs do float. Once the fuel is gone, they're just empty cans. I don't know how, or if water is kept from entering the big hole at the bottom.

Did I read that correctly? Each of those parachutes weighs a ton? Never mind trying to steer the thing into a small target, it's literally a massive waste to lift anything that isn't actually payload. Every extra part that isn't actually rocket goes to the wrong side of the scaling issue.

Also, Elon wants to land on Mars and come home. Regardless of how one feels about that project, I feel safe in assuming that plays into his current decisions.

[Dadhawk]

Originally Posted by Ultramaroon

The SRBs do float. Once the fuel is gone, they're just empty cans. I don't know how, or if water is kept from entering the big hole at the bottom.

Did I read that correctly? Each of those parachutes weighs a ton? Never mind trying to steer the thing into a small target, it's literally a massive waste to lift anything that isn't actually payload. Every extra part that isn't actually rocket goes to the wrong side of the scaling issue.

Thanks for the SRB info. Yea I suppose they would float before water ingress sinks them anyway.

I saw that too on the chutes and was surprised at the total weight. Still lighter I would imagine than enough fuel for the SpaceX landing which subjects the same weight penalty.

[Ultramaroon]

Originally Posted by Dadhawk

Still lighter I would imagine than enough fuel for the SpaceX landing which subjects the same weight penalty.

Ah! Good point. Thanks.

[Irace86.2.0]

Originally Posted by Spuds

The ocean is a pretty big net though. Parachutes like that are neither accurate nor precise.

I would imagine side thrusters and the winglets could correct for wind, but that is just me guessing wind would have a low impact against the inertia and momentum of 500 tons.

[Ultramaroon]

Originally Posted by Irace86.2.0

I would imagine side thrusters and the winglets could correct for wind, but that is just me guessing wind would have a low impact against the inertia and momentum of 500 tons.

Think about the chutes themselves, flying kites, even umbrella in a slight breeze should bring some perspective.

[Dadhawk]

Originally Posted by Ultramaroon

Ah! Good point. Thanks.

It's one of those diminishing return things... How much fuel do you need to fly the fuel that flies the fuel that flies the fuel for landing.....

[Ultramaroon]

Originally Posted by Dadhawk

It's one of those diminishing return things... How much fuel do you need to fly the fuel that flies the fuel that flies the fuel for landing.....

Oh, yeah! I smacked my forehead as soon as you mentioned it. Good stuff.

[x808drifter]

Cost/time of water landing and recovery w/ parachute then prep for relaunch vs Land and reuse.

Figure the parachute way is initially cheaper but removing all the equipment and personnel for is must save a bunch.

Wonder where the break even point is.
Hope it's less than 20-50 launches before landing it starts to become cheaper. (for Falcon-9)

[Dadhawk]

The other factor is that sometimes you need every ounce of fuel to get to lift the payload. Even SpaceX has plans to recover some rockets and "sacrifice" others for the good of the mission.

Also, if I recall correctly, SpaceX doesn't recover the center booster of the Falcon Heavy, only the two outside ones.

there is a similar plan for Starship where sometimes they'll recover the first stage and sometimes they won't.

[gen3v8]

Originally Posted by Dadhawk

The other factor is that sometimes you need every ounce of fuel to get to lift the payload. Even SpaceX has plans to recover some rockets and "sacrifice" others for the good of the mission.

Like Apollo 11. Enough fuel to break earth orbit, fly to the moon,power land, take off again and break lunar orbit for the return. All in, fuel hungry, 70`s tech.

[Irace86.2.0]

Originally Posted by Ultramaroon

Think about the chutes themselves, flying kites, even umbrella in a slight breeze should bring some perspective.

Well, it could be about this, where scaling changes the relationship. Maybe lateral winds acting on an object of a large mass with significant total momentum would have a hard time pushing it significantly off course like trying to veer the Titanic away from an iceberg.

When I went skydiving, we landed on a ten by twenty foam mat from 30k feet. There are GPS guided parachute systems already in use for dropping supplies and Humvees (Source 1, Source 2), so I have to imagine that with the grid fins, side thrusters, GPS systems, and with the sheer mass of the object, that landing in a reasonable zone would be achievable.

The reentry puts the booster fairly vertical, so it would be a matter of devising a way of catching a massive object.

[alex87f]

For something as sensitive to defects as aerospace, I'm surprised the booster having been immersed in seawater (and not being cleaned for probably several hours) doesn't require to change / clean / repaint every single panel, for a higher cost than building new one.

Maybe boosters are that expensive.