Author Topic: DARPA Experimental Spaceplane 1 (XS-1) Program  (Read 419521 times)

Offline Khadgars

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #820 on: 07/21/2018 05:30 pm »
Great article.  But is AR saying that they finally achieved with the SSME what they set out to do 35 years ago?  Borescoping, inspecting bolts, and the figuring out of the dry time of any moisture....this only can be accomplished now?  After the program has long ended and the Orbiters are in museums?   ???
What might've been....

Why do you think the SSME was the limiting factor?  The shuttle was much more than just the SSME , for instance tile inspection required much longer than 24 hours.
Evil triumphs when good men do nothing - Thomas Jefferson

Offline envy887

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #821 on: 07/21/2018 06:48 pm »
Has it been mentioned yet how this thing will get back to the launch site? Presumably it can't just glide back.

Glide back is exactly the plan.

Offline sunworshipper

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #822 on: 07/21/2018 08:42 pm »
Quote
After deploying the upper stage, the booster is an unpowered glider. For lower speed deployments, it will flyback to a landing field at the launch site; for higher speed deployments that take it beyond range of a return to the launch site, it can land on runways downrange.

Offline Prettz

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #823 on: 07/24/2018 03:45 pm »
Quote
After deploying the upper stage, the booster is an unpowered glider. For lower speed deployments, it will flyback to a landing field at the launch site; for higher speed deployments that take it beyond range of a return to the launch site, it can land on runways downrange.
So I guess it's mostly going to be gliding to downrange sites. I'm not sure what kind of launch would allow it to glide back to the launch site.

Offline envy887

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #824 on: 07/24/2018 05:39 pm »
Quote
After deploying the upper stage, the booster is an unpowered glider. For lower speed deployments, it will flyback to a landing field at the launch site; for higher speed deployments that take it beyond range of a return to the launch site, it can land on runways downrange.
So I guess it's mostly going to be gliding to downrange sites. I'm not sure what kind of launch would allow it to glide back to the launch site.

I'm not sure what launch sites and azimuths would allow it to land downrange. This needs a runway, not a barge. There aren't many runways downrange from existing launch sites.

Offline Prettz

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #825 on: 07/24/2018 07:28 pm »
I'm probably just misunderstanding this thing's operations. I was imagining it launching on space shuttle like trajectories so it could glide back to land somewhere up the coast.

Is the idea that it's going to be launching on more lofted trajectories so it's never very far downrange at separation?

Offline envy887

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #826 on: 07/25/2018 01:44 am »
I'm probably just misunderstanding this thing's operations. I was imagining it launching on space shuttle like trajectories so it could glide back to land somewhere up the coast.

Is the idea that it's going to be launching on more lofted trajectories so it's never very far downrange at separation?

I'm not sure, but I imagine a depressed trajectory is also an option as long as the upper stage has a good amount of thrust. Keeping the booster apogee low will reduce the time before reentry, which limits the downrange distance and makes it easier to glide back.

Offline ncb1397

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #827 on: 07/25/2018 01:48 am »
Why not do a boost back maneuver?

Offline ZachS09

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #828 on: 07/25/2018 01:51 am »
Why not do a boost back maneuver?

Probably because the AR-22 is not restartable.
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Offline ncb1397

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #829 on: 07/25/2018 01:54 am »
Why not do a boost back maneuver?

Probably because the AR-22 is not restartable.

Why do you have to cut the engine off?

Shuttle RTLS:

Quote
Return to launch site (RTLS) was the first abort mode available and could be selected just after SRB jettison. The Shuttle would continue downrange to burn excess propellant, as well as pitch up to maintain vertical speed in aborts with an SSME failure. After burning sufficient propellant, the vehicle would be pitched all the way around and begin thrusting back towards the launch site
https://en.wikipedia.org/wiki/Space_Shuttle_abort_modes
« Last Edit: 07/25/2018 01:58 am by ncb1397 »

Offline ZachS09

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #830 on: 07/25/2018 01:58 am »
Why not do a boost back maneuver?

Probably because the AR-22 is not restartable.

Why do you have to cut the engine off?

Well, the engine can be reused for future flights, but once its single burn is completed, it's not ignited during the glideback to landing.
Liftoff for St. Jude's! Go Dragon, Go Falcon, Godspeed Inspiration4!

Offline QuantumG

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #831 on: 07/25/2018 02:00 am »
Why do you have to cut the engine off?

Shuttle RTLS:
<snip>

Right, so you're gunna do staging with the SSME running?


Human spaceflight is basically just LARPing now.

Offline ncb1397

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #832 on: 07/25/2018 02:03 am »
Why do you have to cut the engine off?

Shuttle RTLS:
<snip>

Right, so you're gunna do staging with the SSME running?

Shuttle boosters staged with the SSMEs running. This is side mount, not top mount.

Offline QuantumG

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #833 on: 07/25/2018 02:06 am »
Shuttle boosters staged with the SSMEs running. This is side mount, not top mount.

Fair 'nuff.
Human spaceflight is basically just LARPing now.

Offline RDoc

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #834 on: 07/25/2018 08:15 pm »
Based on the picture, aren't they going to have falling ice and/or insulation issues with the second stage?

Those wings and winglets also look pretty big for anything like Mach 10 to me, but I'm no expert.

Offline envy887

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #835 on: 07/25/2018 08:30 pm »
Why do you have to cut the engine off?

Shuttle RTLS:
<snip>

Right, so you're gunna do staging with the SSME running?

Shuttle boosters staged with the SSMEs running. This is side mount, not top mount.

The SRBs were not running, they were essentially burnt out which reduces the risk of recontacting. And more importantly, nobody cared if the SSMEs smoked them on the way past.

Boeing's promo video shows MECO followed by staging in freefall:

Offline mainmind

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #836 on: 08/26/2018 09:17 pm »
Just a quick question. The Boeing Phantom Express spaceplane is designed to deliver an expendable upper stage carrying a small satellite into orbit for rapid and responsive space access. Could that expendable upper stage be replaced with, or carry, an X-37B vehicle, to allow true two-stage to orbit full reusability and some really interesting applications for the combination?

I think the short answer to you question is no. The XS-1's disposable upper stage probably cannot be replaced by the X-37B.

The XS-1 is being designed to launch a 3,000 lbm satellite to orbit http://www.spacedaily.com/reports/Northrop_Grumman_Developing_XS_1_Experimental_Spaceplane_Design_for_DARPA_999.html https://www.militaryaerospace.com/articles/2013/11/darpa-xs1-spaceplane.html
The X-37B, according to public sources, has a launch mass of 11,000 lbm https://en.wikipedia.org/wiki/Boeing_X-37.

In quick searches, I couldn't find any information public that indicates the launch mass of the XS-1 second stage that carries the 3 klbm payload to orbit. Ignoring physical dimensions and aerodynamic issues of a spaceplane piggy-backing another spaceplane, the question becomes:
1.  what is the launch mass of the XS-1 second stage (including payload);
2. what is the  the delta-V the XS-1 provides;
3. what is the maximum delta-V of the X-37B (Wikipedia indicates initial requirements targeted 3.1 km/s);
4. what is the final payload mass to orbit of the X-37B.

I don't think the X-37B numbers will be published as long as its operational. Of all of its launches to date, it has been encapsulated within a payload fairing until reaching the extents of the atmosphere. Wikipedia says the planned wingspan of the XS-1 is 62 feet (19m) and the X-37B wingspan is 14 ft 11 in (4.55 m). So it is conceivable that the X-37B could at least be mounted to the XS-1 in some fashion. The inert mass fraction of the X-37B is going to be higher than any expendable upper stage it is currently planned to fly, significantly eating into deliverable payload mass to orbit.

If rocket stages were like Lego vehicles, the resulting system (without fairing) would be reminiscent of early shuttle concepts, but smaller.

HTH

Offline Kryten

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #837 on: 08/27/2018 01:02 pm »
In quick searches, I couldn't find any information public that indicates the launch mass of the XS-1 second stage that carries the 3 klbm payload to orbit.
Several companies developing small launch vehicles have received DARPA study contracts for production of the second stage; it's an outsourced solution that hasn't yet been selected.

Offline mainmind

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #838 on: 08/27/2018 01:24 pm »
In quick searches, I couldn't find any information public that indicates the launch mass of the XS-1 second stage that carries the 3 klbm payload to orbit.
Several companies developing small launch vehicles have received DARPA study contracts for production of the second stage; it's an outsourced solution that hasn't yet been selected.

That explains the lack of detail. Thanks for this clarification.

Offline envy887

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Re: DARPA Experimental Spaceplane 1 (XS-1) Program
« Reply #839 on: 08/27/2018 01:24 pm »
In quick searches, I couldn't find any information public that indicates the launch mass of the XS-1 second stage that carries the 3 klbm payload to orbit.
Several companies developing small launch vehicles have received DARPA study contracts for production of the second stage; it's an outsourced solution that hasn't yet been selected.

IIRC some old DARPA presentations were base-lining a upper stage mass around 8 tonnes.

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