This looks like a fuel line, for orbital fuel depots. Tanks could be used as a building material instead of burning though.
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Doesn't vertical landing necessarily use more fuel than landing aerodynamically, like the Space Shuttle? I would want a craft that takes off and lands like an airplane, ideally.exoscientist":1i98k8gd said:
Not necessarily. First you start your powered braking above the atmosphere, loose most of the speed before getting into thicker layers, where aero-braking gets hot. This is how you reduce need for a thermal protection, which can make a big part of mass of a lander.neutrino78x":1054udxt said:Doesn't vertical landing necessarily use more fuel than landing aerodynamically, like the Space Shuttle? I would want a craft that takes off and lands like an airplane, ideally.exoscientist":1054udxt said:
Bob, please post SS2 realted material in the SS2 threadexoscientist":f4glpwyr said:Video of SpaceShipTwo assembly, showing the all-composite construction, including the structural members:
An innovative method for joining composite structures implemented by Northrop Grumman has passed a series of intensive structural tests, paving the way for the use of composites in future spacecraft.
It was also very inspiring, cost measly 1.3 G$, comparing to stick, and quoting wikipedia:Astro_Robert":h99r7pln said:Please keep in mind as someone mentioned at the top of the thread that X-33 was only a technology demonstrator granted experimental status and meant only to advance certain key technologies to a higher Technology Readiness Level (TRL) to provide risk reduction for the VentureStar follow on vehicle.
http://en.wikipedia.org/wiki/X-33Thus, the X-33 was not only about honing space flight technologies, but also about successfully demonstrating the technology required to make a commercial reusable launch vehicle possible.
We do what we can with information we have available. Show us more, we'll know more and you are more than welcome to show faults in our reasoning, that's the point, right ?Astro_Robert":h99r7pln said:Part of me just finds it a little bit humorous when laypeople with apparently little expertise or knowledge of things self proclaim as to whout should have been or could be possible.
The X-33 was used as an example for what is possible IF instead of focusing on hydrogen as the fuel for a SSTO we used dense propellants. Kerosene is just the most commonly used one. It probably is not the most ideal dense propellant to use for the purpose.Astro_Robert":prfwthoq said:Please keep in mind as someone mentioned at the top of the thread that X-33 was only a technology demonstrator granted experimental status and meant only to advance certain key technologies to a higher Technology Readiness Level (TRL) to provide risk reduction for the VentureStar follow on vehicle.
Cost issues have been addressed in this thread, and it seams prices went down a lot. There are new ways to bind structure together, as you can also read about in this thread.Astro_Robert":1uc5v1wg said:As far as all-composites, in practice one would have to balance any weight savings with fabrication cost and lifetime. Composites are usually more expensive to fabricate and are often more fragile and can be difficult or impossible to repair. One can use composites as ‘black-metal’ taking composites sections and bolting them together as one would a metal piece. However a lot of the weight is in the joint fasteners so that solves little. If one attempts to make a large bonded structure so save weight, one encounters massive fabrication and quality control issues, again going to cost.
If the cost for carbon structure is too high, if it doesn't fly enough, then maybe lifecycle costs could probably be greater ...Astro_Robert":1uc5v1wg said:An all-composite vehicle would likely cost much more to fabricate, increasing the costs to be amortized over its lifetime. Chances are that the cost penalty far outweighs the weight savings for an expendable vehicle to be made entirely of composites. The weight penalty of not staging probably requires low cost requiring fabrication and thus would tend to eliminate an all-composite disposable rocket. If the lifetime is not sufficiently long, then the lifecycle costs of operating a re-usable SSTO could actually be greater than that of a staged expendable.
Which launcher you had in mind for 100 M$ ? Can't remember any such cheap thing in 10t to LEO class ? Where did you get 5 $B ?Astro_Robert":1uc5v1wg said:There are 2 primary considerations driving people to consider SSTO vehicles such as X-33: Cost and Responsiveness. One would imagine that not throwing away a $100M rocket every time would save money, but can a $5B vehicle really fly well over 50 times (depreciation vs inflation), the Shuttles have only flown like 30 times each and are falling far short of their claim in that regards. On the Responsiveness side, it is expected that a re-usable vehicle would have better responsiveness but again Shuttle flies only a few times per year per vehicle, and it is the composite TPS that has been one of the drivers in this regard.
If it did a bit more braking above atmosphere, had lower entry speeds, it would require even less thermal protection or had less severe requirements for it.Astro_Robert":1uc5v1wg said:X-33 was not all-composite. It actually used metallic primary Thermal Protection System (TPS), and it weighed comparable to or less than the shuttle composite TPS. This is because the shuttle possesses a primary Aluminum skin plus pads plus ceramic bricks, whereas the X-33 only utilized the metallic shield. Being metallic, this shield was tougher than Shuttle tile, and likely would have required much less maintenance. The reason X-33 could use it instead of Shuttle tile, was that as a Hypersonic glider, its re-entry angle was not as steep and hot as shuttle. This slightly more benign environment allowed the use of this newer material.
It seams to me, that a lot of that is being addressed, otherwise airlines and car companies would not start introducing this materials in their production lines.Astro_Robert":1uc5v1wg said:Again, there are problems with composites that have to be considered, when one contemplates their advantages. Yes they tend to be lightweight, but can be difficult to produce and are not usually as damage tolerant as metal. They tend to have very low co-efficient of thermal expansion which tends to be good in a space vehicle, but necessary metallic pieces may not be compatible with their much different thermal properties.