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I have found this interestin video about Airbus Adeline semi-resuable system
http://www.dailymail.co.uk/sciencetech/ … eline.html
The main LOX-LH2 engine and the avionics of a new version of Ariane are pleaced inside a winged nacelle, that detaches from the first stage tank, reenters and lands like a conventional aeroplane using two propellers, resulting up to 30% launch cost reduction.
It may be simpler to make it work than Falcon R resuable first stage.
Last edited by Quaoar (2015-06-12 08:53:09)
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Hi Quaoar:
That's an interesting concept Airbus came up with. It addresses the severe technical difficulties of doing full stage recovery by just recovering the most expensive part. You give up some on your financial return to solve the easier technical problem.
Airbus is at the model stage, while Spacex is now making full scale flight attempts. The jury is out who might succeed first. I rather suspect we'll see various concepts from multiple companies, now that Spacex has gotten as far as it has. Launch prices are only as low as they, because of Spacex.
So far their lower prices have derived from solving the issue of simpler, cheaper logistics in manufacture, preparation, and launch. They will be hard to beat if they succeed at reusing stages.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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Hi Quaoar:
That's an interesting concept Airbus came up with. It addresses the severe technical difficulties of doing full stage recovery by just recovering the most expensive part. You give up some on your financial return to solve the easier technical problem.
Airbus is at the model stage, while Spacex is now making full scale flight attempts. The jury is out who might succeed first. I rather suspect we'll see various concepts from multiple companies, now that Spacex has gotten as far as it has. Launch prices are only as low as they, because of Spacex.
So far their lower prices have derived from solving the issue of simpler, cheaper logistics in manufacture, preparation, and launch. They will be hard to beat if they succeed at reusing stages.
GW
My money's on Space X. Sounds like Airbus are just playing in the sandpit.
Let's Go to Mars...Google on: Fast Track to Mars blogspot.com
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I dunno, Louis. The jury may still be out on that one. Airbus is far behind (and likely not yet well-funded to do this), but Spacex has already run into repeated difficulties solving their far more demanding recovery problem. We'll have to see how this plays out over time. On a scale of years.
My opinion is that Spacex has made their problem more difficult than it needs to be by two possible flaws in their approach. (1) Not having a low-enough 1-engine thrust to permit hover, means that they cannot slow down touchdown timelines to recover from unplanned off-design attitude, speed, and location excursions. (2) I rather doubt that engine gimbal has the authority and the speed to control attitude upsets right at touchdown (I bet they will eventually need attitude thrusters for that). Those grid fins are useless for slow-speed attitude control.
Their problems about landing that stage have less to do with their admittedly very fine expertise in rocket engines, and a whole lot more to do with the control of flight vehicles at less-than-optimal conditions. That's the same area that caused them stage separation troubles with Falcon 1, when they first got started several years ago.
It takes an experienced old hand on your staff to sort out troubles like that. Spacex does not like to hire anyone but "young turks" under 40-45 years of age, because they like to work them 60 hours a week, and older guys won't or can't be worked that way. It's a management staffing approach that serves them well much of the time, but occasionally shoots them right in the foot.
GW
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
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I dunno, Louis. The jury may still be out on that one. Airbus is far behind (and likely not yet well-funded to do this), but Spacex has already run into repeated difficulties solving their far more demanding recovery problem. We'll have to see how this plays out over time. On a scale of years.
My opinion is that Spacex has made their problem more difficult than it needs to be by two possible flaws in their approach. (1) Not having a low-enough 1-engine thrust to permit hover, means that they cannot slow down touchdown timelines to recover from unplanned off-design attitude, speed, and location excursions. (2) I rather doubt that engine gimbal has the authority and the speed to control attitude upsets right at touchdown (I bet they will eventually need attitude thrusters for that). Those grid fins are useless for slow-speed attitude control.
Their problems about landing that stage have less to do with their admittedly very fine expertise in rocket engines, and a whole lot more to do with the control of flight vehicles at less-than-optimal conditions. That's the same area that caused them stage separation troubles with Falcon 1, when they first got started several years ago.
GW
Hi GW
It's ever a pleasure to read your posts.
It seems to me SpaceX is at a dead point, being unable to recover the first stage without redesign it, adding low-thrust rockets for hovering and more powerful attitude control rockets to counteract strong winds. But all these upgrades have a R& D cost and add more weight reducing the payload.
It takes an experienced old hand on your staff to sort out troubles like that. Spacex does not like to hire anyone but "young turks" under 40-45 years of age, because they like to work them 60 hours a week, and older guys won't or can't be worked that way. It's a management staffing approach that serves them well much of the time, but occasionally shoots them right in the foot.
GW
Why not to simply hire experienced old guys as consultants to solve specific problems?
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It seems to me SpaceX is at a dead point, being unable to recover the first stage without redesign it, adding low-thrust rockets for hovering and more powerful attitude control rockets to counteract strong winds. But all these upgrades have a R& D cost and add more weight reducing the payload.
SpaceX started with Grasshopper. They demonstrated ability to land a rocket that size with one engine. The problem is the first stage of Falcon 9 is landing faster and harder than Grasshopper. And Grasshopper used just one engine, so number of engines is not the issue. Look at video of Grasshopper: it did hover, and did land slowly, and perfectly vertical. But the last landing of Falcon 9 landed fast, hard, and at an angle. With a vehicle that tall and narrow, any horizontal momentum will cause it to fall over. In the case of the last landing, it didn't just tip over, it skidded sideways off the platform.
Looks like someone is trying to minimize landing propellant by calculating zero vertical speed just as landing feet touch the platform. As many have pointed out, with cross wind and platform movements due to waves, that doesn't work. Hover and slow vertical descent for the last few feet, absolutely necessary. They did it with Grashopper, but that landed on a concrete pad on land. Landing on anything floating at sea is more difficult, the landing platform is moving. Everyone here agrees, hover is necessary. Or at least slow to very slow vertical descent, directly over the landing spot with no horizontal speed. It takes more propellant that way, but to quote the running shoe slogan "Just Do It!".
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