Author Topic: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)  (Read 1086014 times)

Offline Jim

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2540 on: 04/14/2024 10:53 pm »

NASA is literally paying for it now, and has been for a decade, and doing so on top of paying for two other cargo vehicles.

No, not really.  NASA is only paying for the cargo flights, not the development.  So, the only monies for mission planning has been given to Sierra, not for vehicle development.

Offline lrk

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2541 on: 04/17/2024 03:57 pm »

Not when it lands at the Shuttle Landing Facility at end of mission, and then has to be towed off back the processing facility several miles away. And that will be even more true when or if it ever lands somewhere else.


Not going to land if rain is eminent.  The shuttle was out on the pad in the rain.

Moisture in the air, and it can rain while Tenacity is being towed off the runway. It is Florida, after all.

The waterproofing in the shuttle tiles was destroyed by entry heating, and thus needed to be reapplied after every flight.  So post-entry the tiles wouldn't be waterproof, anyway. 

So I also don't understand why waterproofing is needed if the spacecraft is always kept in an airconditioned fairing.

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2542 on: 04/17/2024 11:37 pm »
Runway landings theoretically imply quick vehicle turn-around for reflight, assuming launcher availability. With "first flight in the fourth quarter of this year" the question becomes how soon the same vehicle can launch again.

How long did it take NAR/NASA to turn around Columbia between STS-1 to STS-2/3/4? Or for SpaceX to achieve rapid relaunch of Falcon 9s?
For the first dozen or so missions I expect long turn arounds as they learn what wears out faster in reality vs theory, and what is doing better than expected. And what comes up that they had not planned for.
« Last Edit: 04/17/2024 11:40 pm by JAFO »
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Offline gongora

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2543 on: 05/04/2024 01:17 am »
0765-EX-ST-2024
NET June
Quote
The tow/taxi test demonstrates multi-system performance over a range of speeds and braking profiles by towing the UDC down the runway at the Shuttle Landing Facility (SLF) at Kennedy Space System (KSC) to a test case specific speed and releasing the UDC such that it controls itself and brakes to a stop.
...
Kennedy Space Center Shuttle Landing Facility
« Last Edit: 05/04/2024 01:17 am by gongora »

Offline MattMason

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2544 on: 05/04/2024 10:22 am »
Runway landings theoretically imply quick vehicle turn-around for reflight, assuming launcher availability. With "first flight in the fourth quarter of this year" the question becomes how soon the same vehicle can launch again.

How long did it take NAR/NASA to turn around Columbia between STS-1 to STS-2/3/4? Or for SpaceX to achieve rapid relaunch of Falcon 9s?
For the first dozen or so missions I expect long turn arounds as they learn what wears out faster in reality vs theory, and what is doing better than expected. And what comes up that they had not planned for.

If the same technologies as used on the Shuttle Orbiter were present on Dream Chaser, I would fully concur.

But we know otherwise, and Sierra appears to avoid those same pitfalls that slowed Orbiter turnaround.

For one, Dream Chaser uses a launch vehicle that has its own integration and assembly metric. Vulcan's still a bit young for us to know the speed that ULA will assemble, fly and assemble again, but this company has been absolute pros with Atlas V, and it seemed Vulcan Cert 1 was a resounding success.

But a key turnaround killer for STS was the use of hypergolic propellants all over that Orbiter. DC Cargo uses, I believe, nitrous oxide/propane, far easier to manage, clean and refill for turnaround. TUFROC leading edge and nose tiles with STS-type silica tiles, but on a much smaller vehicle should aid in repair and refit of any tile issues.

The only question for me is the assembly speed of Shooting Stars. They're the throwaway item, is large, and is as critical as the Apollo and Starliner Service Modules for on-orbit power and maneuvering.

I agree; no plan escapes first contact with reality, and this is really a new vehicle. But not all spaceplanes are the same.
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Online DanClemmensen

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2545 on: 05/04/2024 02:33 pm »
For one, Dream Chaser uses a launch vehicle that has its own integration and assembly metric. Vulcan's still a bit young for us to know the speed that ULA will assemble, fly and assemble again, but this company has been absolute pros with Atlas V, and it seemed Vulcan Cert 1 was a resounding success.
I'm confident that the ULA team is highly professional, but they do not have much experience with quick turnaround. They have never launched more than 16 times in a year ( once, in 2009) and they have never launched more than 9 Atlas V in a year (twice, 2014 and 2015). They will need to learn how to maintain a high cadence to launch Kuiper on Vulcan, but it takes time. The tenth Atlas V mission was five years after the first one, so launching Vulcan at high cadence in 2025 does not seem likely.

Online JAFO

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2546 on: 05/04/2024 04:20 pm »
Not to mention that NAR/NASA had to dang near invent everything associated with Shuttle, soft and hardware, whereas SNC gets to benefit from the knowledge gained from the 28 years the Shuttle flew.


I did smile once I realized what 0765-EX-ST-2024 meant. Going to be exciting/cute to see Tenacity being towed and released on the SLF runway. SNC, if you’re reading this I hope you position her next to the plaque embedded in the runway marking STS-135 Wheel stop and get some overhead pics, send it out on Twitter/X it out captioned “Wings are back.”
« Last Edit: 05/04/2024 05:30 pm by JAFO »
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Online DanClemmensen

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2547 on: 05/04/2024 04:39 pm »
The only question for me is the assembly speed of Shooting Stars. They're the throwaway item, is large, and is as critical as the Apollo and Starliner Service Modules for on-orbit power and maneuvering.
Starliner's SM, and Dragon's Trunk are also throwaway. The SM is complex and expensive. The Trunk is a lot simpler. How does Shooting Star compare to these?

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2548 on: 05/04/2024 04:50 pm »
Was there ever any reason given why they stopped plans to human-rate the -100 DC and start from zero with a clean sheet -200?
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Offline GreenShrike

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2549 on: 05/04/2024 04:58 pm »
The only question for me is the assembly speed of Shooting Stars. They're the throwaway item, is large, and is as critical as the Apollo and Starliner Service Modules for on-orbit power and maneuvering.
Starliner's SM, and Dragon's Trunk are also throwaway. The SM is complex and expensive. The Trunk is a lot simpler. How does Shooting Star compare to these?

It's probably the most expensive of the service modules, containing, as it does, actual pressurized volume for a few tonnes of cargo, three external hardware mounting points, as well as solar panels, radiators and an ACS.

It's like a mini-Cygnus spacecraft all by itself.
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Offline deltaV

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2550 on: 05/04/2024 07:53 pm »
Was there ever any reason given why they stopped plans to human-rate the -100 DC and start from zero with a clean sheet -200?

It's probably the most expensive of the service modules

A grunt in the universe's spaceflight economics department dislikes airplanes and has sabotaged the cost effectiveness of dozens of space planes and air-breathing launch vehicles. Their favored tool is messing with the laws of physics, e.g. poor hypersonic lift-to-drag ratios, inefficient hypersonic air-breathing engines, reentry heating that favors blunt bodies, and a rocket equation that severely punishes dry mass, but when a program risks being successful anyway they find excuses to raise its costs. That's how Dream Chaser got separate cargo and crew vehicles, an expensive service module, and a 20-year development program.  :)

Offline edzieba

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2551 on: 05/13/2024 02:56 pm »
For one, Dream Chaser uses a launch vehicle that has its own integration and assembly metric. Vulcan's still a bit young for us to know the speed that ULA will assemble, fly and assemble again, but this company has been absolute pros with Atlas V, and it seemed Vulcan Cert 1 was a resounding success.
I'm confident that the ULA team is highly professional, but they do not have much experience with quick turnaround.
A 7-day turnaround for AV-059 to AV-058 (Mexsat-2 to USA 264) is ULAs record for same-vehicle turnaround, and they've pulled off a few 5-day Atlas-to-Delta or Delta-to-Atlas turnarounds.
By my count, ULA have pulled off 6 week-or-less turnarounds and 41 month-or-less turnarounds. I don't think launcher turnaround time is going to be the long pole for Dream Chaser reflight.

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2552 on: 05/13/2024 03:09 pm »
For one, Dream Chaser uses a launch vehicle that has its own integration and assembly metric. Vulcan's still a bit young for us to know the speed that ULA will assemble, fly and assemble again, but this company has been absolute pros with Atlas V, and it seemed Vulcan Cert 1 was a resounding success.
I'm confident that the ULA team is highly professional, but they do not have much experience with quick turnaround.
A 7-day turnaround for AV-059 to AV-058 (Mexsat-2 to USA 264) is ULAs record for same-vehicle turnaround, and they've pulled off a few 5-day Atlas-to-Delta or Delta-to-Atlas turnarounds.
By my count, ULA have pulled off 6 week-or-less turnarounds and 41 month-or-less turnarounds. I don't think launcher turnaround time is going to be the long pole for Dream Chaser reflight.
AV-059 to AV-058 was in 2015. 059 at CCAFS and 058 was at VAFB.  Separate teams on separate pads on separate coasts, nine years ago, with a rocket they had 9 years of experience with. The ULA team has a better chance than anyone else to ramp quickly, but I think it's still a challenge.

Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2553 on: 05/13/2024 05:59 pm »
It's like a mini-Cygnus spacecraft all by itself.

I wonder if in a year or so, after the first flight, Sierra Space will start marketing Shooting Star as an all purpose solution the way Northrop grumman do with Cygnus.

Gateway Logistics? Shooting Star.
Free Flier? Shooting Star.
Lunar Surface Hab? Shooting Star.
Returning Manufactured Goods from LEO? Shooting Star with HIAD.
Wait, ∆V? This site will accept the ∆ symbol? How many times have I written out the word "delta" for no reason?

Online adrianwyard

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2554 on: 05/13/2024 06:08 pm »
Throwing such a capable (~human rated) vehicle away each time does feel like a waste, and will ensure high cost of DC100.

HIAD seems like a great idea - tech demo at least - but I don't see how it could be integrated, not easily anyhow. Maybe the hatch to DC would have an ablative heat shield added? CG seems like it would be in an inconvenient location too.
« Last Edit: 05/13/2024 06:09 pm by adrianwyard »

Offline Jim

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2555 on: 05/13/2024 07:14 pm »
It's like a mini-Cygnus spacecraft all by itself.

I wonder if in a year or so, after the first flight, Sierra Space will start marketing Shooting Star as an all purpose solution the way Northrop grumman do with Cygnus.

Gateway Logistics? Shooting Star.
Free Flier? Shooting Star.
Lunar Surface Hab? Shooting Star.
Returning Manufactured Goods from LEO? Shooting Star with HIAD.

No.  Much like the Dragon trunk it is not a standalone spacecraft.
« Last Edit: 05/13/2024 07:15 pm by Jim »

Offline Asteroza

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2556 on: 05/14/2024 12:04 am »
It's like a mini-Cygnus spacecraft all by itself.

I wonder if in a year or so, after the first flight, Sierra Space will start marketing Shooting Star as an all purpose solution the way Northrop grumman do with Cygnus.

Gateway Logistics? Shooting Star.
Free Flier? Shooting Star.
Lunar Surface Hab? Shooting Star.
Returning Manufactured Goods from LEO? Shooting Star with HIAD.

No.  Much like the Dragon trunk it is not a standalone spacecraft.

Sure, Dragon trunk is basically a shell with a radiator and solar panel surface mount, but Shooting Star seemed far more substantial though?

Offline StraumliBlight

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2557 on: 05/14/2024 12:21 am »
Sure, Dragon trunk is basically a shell with a radiator and solar panel surface mount, but Shooting Star seemed far more substantial though?

Sierra Space market a Free Flyer Shooting Star in their hardware catalog.

Offline Yellowstone10

Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2558 on: 05/14/2024 01:26 am »
Sierra Space market a Free Flyer Shooting Star in their hardware catalog.

Interesting to note in that graphic that they've depicted both a JEM Exposed Facility payload and an ExPRESS Payload Adapter-mounted payload on the exterior of the Shooting Star. Wonder if we'll start seeing that cut into the "market share" for unpressurized payloads launched in Cargo Dragon's trunk?

Offline Jim

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Re: Sierra Space Dream Chaser DISCUSSION Thread (was SNC)
« Reply #2559 on: 05/14/2024 01:26 am »
Sure, Dragon trunk is basically a shell with a radiator and solar panel surface mount, but Shooting Star seemed far more substantial though?

Sierra Space market a Free Flyer Shooting Star in their hardware catalog.

Completely different vehicle.

 

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