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Skylon

By Skylon
in Science & Spaceflight

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tater

tater

Posted
Posted

There were some hi res photos on NSF a bit ago that showed they had added RCSE to that area of the vehicle. They were also looking like they were for roll, mounted to fire at a tangent, vs the vents which seem to be radial. It's on page 118 of the NSF pictures thread I think.

Also this post:

https://forum.nasaspaceflight.com/index.php?topic=50773.msg2083155#msg2083155

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mikegarrison

mikegarrison

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Hmm. I guess "barge turnaround time" is now officially a known obstacle to rocket reusability. This launch would not have been scrapped for a single-use rocket.

On the other hand, it also demonstrates that SpaceX must actually be saving money reusing rockets, because they are apparently not willing to go full-expendable just to keep a schedule for their internal customer Starlink.

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mikegarrison

mikegarrison

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@tater raised this question before, but if this were the ISS crew launch, and the only weather obstacle was that they couldn't recover the booster, would they be launching? I wonder what the schedule v. booster recovery priority is for that?

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tater

tater

Posted
Posted (edited)
1 hour ago, mikegarrison said:

Hmm. I guess "barge turnaround time" is now officially a known obstacle to rocket reusability. This launch would not have been scrapped for a single-use rocket.

They already knew this, which is why they have 2, and are building a third. JRTI has been refitted, and would have been available, but they want to put her through sea trials first.

Not sure where A Shortfall of Gravitas is in fitting out, actually.

Quote

On the other hand, it also demonstrates that SpaceX must actually be saving money reusing rockets, because they are apparently not willing to go full-expendable just to keep a schedule for their internal customer Starlink.

Yeah, true.

So far the only other reusable vehilce used operationally was Shuttle. They must have had weather conditions that scrubbed launches for downrange weather I assume, right? I know RTLS was always dodgy to be possible at all, but didn't they have an over the hill abort to Spain or something?

5 minutes ago, mikegarrison said:

@tater raised this question before, but if this were the ISS crew launch, and the only weather obstacle was that they couldn't recover the booster, would they be launching? I wonder what the schedule v. booster recovery priority is for that?

Yeah, this is interesting. Presumably since NASA is paying for a new booster they can drive schedule at the expense of the booster? ISS windows are instantaneous, so while they have contingency launch windows, if the weather is good at the Cape, and lousy downrange... they might miss all windows if they delay.

Edited by tater
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mikegarrison

mikegarrison

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Posted
Just now, tater said:

So far the only other reusable vehilce used operationally was Shuttle. They must have had weather conditions that scrubbed launches for downrange weather I assume, right? I know RTLS was always dodgy to be possible at all, but didn't they have an over the hill abort to Spain or something?

Yeah, but that's different. The equivalent would actually be scrubbing a launch because they were afraid they would not be able to recover the SRBs.

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tater

tater

Posted
Posted
Just now, mikegarrison said:

Yeah, but that's different. The equivalent would actually be scrubbing a launch because they were afraid they would not be able to recover the SRBs.

True for the crew vehicle, yeah.

It comes down to cost, I guess. NASA eventually let them use previously flown boosters on CRS flights, maybe that becomes a thing with crew missions? In that case, maybe they intentionally use flown boosters in case they need to expend it? That or again, NASA pays full ticket, and SpaceX eats the booster since it's paid for anyway. (?)

Really interesting question.

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Brotoro

Brotoro

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Is NASA's contract with SpaceX not a matter of public record? I presume if NASA is paying full price for the booster with the understanding that it gets thrown away if there is bad recovery weather, it should say something about that. But if SpaceX gave NASA the option to take a cheaper booster price in exchange for the option to delay for booster recovery reasons, it should say that.

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tater

tater

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I know they are doing ASDS landings for DM missions... I wonder if they can possibly do an RTLS at some point in future with Crew Dragon? they might always have fo land downrange because they can't loft the trajectory for appropriate abort dynamics for the crew vehicle, so maybe it's always ASDS. Maybe if it turns out after a while they are comfortable with margins they could do RTLS and at least the weather would be the same for launch/landing? Or even a hybrid trajectory? That would be not landing pure downrange, but actually doing a boostback, just not all the way to the Cape?

4 minutes ago, Brotoro said:

Is NASA's contract with SpaceX not a matter of public record? I presume if NASA is paying full price for the booster with the understanding that it gets thrown away if there is bad recovery weather, it should say something about that. But if SpaceX gave NASA the option to take a cheaper booster price in exchange for the option to delay for booster recovery reasons, it should say that.

https://www.nasa.gov/sites/default/files/files/CCtCap_SpaceX_508.pdf

A quick skim doesn't show it. My guess is they eat the booster.

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mikegarrison

mikegarrison

Posted
Posted (edited)
11 minutes ago, Brotoro said:

Is NASA's contract with SpaceX not a matter of public record? I presume if NASA is paying full price for the booster with the understanding that it gets thrown away if there is bad recovery weather, it should say something about that. But if SpaceX gave NASA the option to take a cheaper booster price in exchange for the option to delay for booster recovery reasons, it should say that.

That sort of stuff isn't always public. At least, not without filing a FOIA request. And even then, they have the right to redact things that are considered "confidential business information".

10 minutes ago, tater said:

I know they are doing ASDS landings for DM missions... I wonder if they can possibly do an RTLS at some point in future with Crew Dragon? they might always have fo land downrange because they can't loft the trajectory for appropriate abort dynamics for the crew vehicle, so maybe it's always ASDS. Maybe if it turns out after a while they are comfortable with margins they could do RTLS and at least the weather would be the same for launch/landing? Or even a hybrid trajectory? That would be not landing pure downrange, but actually doing a boostback, just not all the way to the Cape?

https://www.nasa.gov/sites/default/files/files/CCtCap_SpaceX_508.pdf

A quick skim doesn't show it. My guess is they eat the booster.

I don't see how they could do a RTLS trajectory and still make an aborted launch survivable.

Edited by mikegarrison
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tater

tater

Posted
Posted
3 minutes ago, mikegarrison said:

I don't see how they could do a RTLS trajectory and still make an aborted launch survivable.

Agreed, pretty sure that is what's driving the downrange landing, shallower reentry on an abort.

Still wonder about a sort of partial RTLS—land on the drone ship, but closer to shore, with a partial boostback, vs just landing where the booster naturally wants to fall after MECO. Of course the bulk of the dv there is killing the 2.x km/s downrange velocity, so maybe it's not possible.

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magnemoe

magnemoe

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Posted
1 minute ago, RCgothic said:

Dragon 2 with full cargo weighs as much as a full Starlink launch, much more than CRS. We've never seen Starlink RTLS so I don't think Dragon2 missions can.

is it that heavy? Anyway the need for an shallow launch trajectory so you can survive an abort, starliner has the same issue but here it was low trust on upper stage with one engine. 

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RCgothic

RCgothic

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Posted (edited)
1 hour ago, magnemoe said:

is it that heavy? Anyway the need for an shallow launch trajectory so you can survive an abort, starliner has the same issue but here it was low trust on upper stage with one engine. 

9.5t empty, 1.3t props, up to 6t Cargo = 16.8t, exactly the same as Starlink.

Edited by RCgothic
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Hannu2

Hannu2

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Posted
3 hours ago, tater said:

So far the only other reusable vehilce used operationally was Shuttle. They must have had weather conditions that scrubbed launches for downrange weather I assume, right? I know RTLS was always dodgy to be possible at all, but didn't they have an over the hill abort to Spain or something?

If I remember correctly, there was a delay in some Shuttle launch because there was bad weather on some airport intended to use in some abort situation. But it was more than a decade ago and I am not sure. Did they have suitable airbases for abort in Africa?

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