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Unmanned U.S. Air Force space plane lands after secret, two-year mission

reuters.com

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Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#91

Post by robotresearcher »

kobeya wrote: post #86
hughes wrote: post #67

Earlier quoted context omitted.

Powered landings after an intense atmospheric deceleration.

No, powered landings all the way down. At least on the Moon and Mars (from orbit). With more fuel you could do the same from Earth, but why bother?

That's cool, I didn't know that. So Dragon 2 is a Soyuz-like passive capsule when landing in atmosphere and a powered spaceship like the Apollo LEM when landing in vacuum. Very cool that they could cram those roles into one vehicle. Looking forward to seeing it work.

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#92

Post by coredog64 »

Retric wrote: post #27
colordrops wrote: post #13

Earlier quoted context omitted.

Capsules aren't inferior. In fact they can land on planets and moons without atmospheres, unlike space planes. And once propulsive landing of capsules is implemented, they can land on Earth without a landing strip, and even on boats.

These things would fit inside the shuttle which creates a very different design with much lower thermal stresses. Remember, the initial shuttle design was actually viewed as an improvement by real rockets scientists even if the project ballooned into ridiculous territory there really is a lot of value in those short stubby wings.

Dynasoar was a contemporary of the Mercury capsule.

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#93

Post by Diederich »

robotresearcher wrote: post #91
kobeya wrote: post #86

Earlier quoted context omitted.

No, powered landings all the way down. At least on the Moon and Mars (from orbit). With more fuel you could do the same from Earth, but why bother?

That's cool, I didn't know that. So Dragon 2 is a Soyuz-like passive capsule when landing in atmosphere and a powered spaceship like the Apollo LEM when landing in vacuum. Very cool that they could cram those roles into one vehicle. Looking forward to seeing it work.

https://youtu.be/1_FXVjf46T8

Work in progress..Well along in progress.

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#94

Post by jessriedel »

blackguardx wrote: post #85
jessriedel wrote: post #68

Earlier quoted context omitted.

There isn't really a sharp distinction, is there? The primary method of generating lift for both wings and lifting bodies is simply the fact that it's an inclined plane moving through a fluid with positive angle of attack.

They each have some length of wing, but get a lot of lift from the shape of the fuselage. These craft wouldn't exist without lifting body research. This space plane and the shuttle shouldn't be derided for gliding into landing. Not using fuel while landing saves precious cargo capacity. If the main argument against them is that they can't land on the moon, I don't understand why a future craft couldn't both glide int…

> Not using fuel while landing saves precious cargo capacity

Those wings are also a lot of mass, and hence take away from payload. In fact, propulsive landing always takes less mass than wings in the limit of large craft size. (You can see this by taking an equivalent limit, the limit of thin atmosphere; for sufficiently thin atmosphere, the amount of surface area you need to brake diverges but the amount of fuel to stop propulsively is fixed.) In this sense, propulsive landings naturally succeed wings as crafts get larger.

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#95

Post by mdorazio »

nradov wrote: post #79
tammer wrote: post #20

Surprised nobody's mentioned this possibility as it usually comes up re: the X-37B. Terrifying but I think not out of the question given the strategic potential of such a weapon. https://en.wikipedia.org/wiki/Kinetic_bombardment

Orbital kinetic bombardment is a silly concept suitable only for cheap sci-fi novels. There's no benefit in having kinetic weapons permanently positioned in orbit. The satellites would be easily tracked and vulnerable to ASAT weapons. They can't strike a target much faster than a ballistic missile launched from land or sea. And they would be much more expensive. Anything in orbit is out of reach of maintenance. It ta…

I think you're forgetting a number of advantages.

1. Surprise. All land-based launch sites are actively monitored all the time, giving countries advance warning when a missile is launched. Submarine launches cut down this warning time, but still light up radar and thermal all over the place. A kinetic impactor falling from LEO can hit its target before the enemy even reports up the chain of command (we're talking single digit minutes).

2. Lack of radioactive fallout while still having larger destructive force than conventional munitions. If you need to destroy an entire air base far behind enemy lines, but don't want nearby population centers to be irradiated, you're looking at pretty bad options today, compared to a kinetic bombardment.

3. You can't really intercept a kinetic impactor. We have the technology right now to shoot small rockets right out of the sky, and at least a chance of intercepting ICBM payloads. With a kinetic rod, though, intercepting it wouldn't really do very much - it's just a big chunk of mass moving really fast. The best you could do is break it into smaller pieces that are still moving really fast.

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#97

Post by mdorazio »

taneq wrote: post #65
tammer wrote: post #20

Surprised nobody's mentioned this possibility as it usually comes up re: the X-37B. Terrifying but I think not out of the question given the strategic potential of such a weapon. https://en.wikipedia.org/wiki/Kinetic_bombardment

People always talk about kinetic strikes in the context of big flashy things like rockets and spaceplanes. I'd be a lot more worried about them being dropped from stratospheric balloons - maybe not so useful for full scale bunker busting but extremely cheap to make and almost indefensible against as a strategic strike system.

This reminds me of a novel weapon from the Daemon novels. Basically, small semi-guided darts dropped from weather balloons that were used as antipersonnel weapons rather than as a replacement for conventional explosives.

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#98

Post by hawkesnest »

nradov wrote: post #75
bjd2385 wrote: post #16

Earlier quoted context omitted.

Way I see it is, if we can land a rover the size of a minivan on a different planet, we should be able to do this without much more effort. Money, perhaps, yes; but, we've already done it.

You might think so, but the difficulty doesn't scale linearly with size and weight. For example there's a practical upper bound on airbags to absorb landing shock; we can't just build larger ones for a capsule carrying humans.

I would imagine that the airbag solution would be rather unpleasant for humans, even if it were possible/practical.

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#99

Post by blackguardx »

jessriedel wrote: post #94
blackguardx wrote: post #85

Earlier quoted context omitted.

They each have some length of wing, but get a lot of lift from the shape of the fuselage. These craft wouldn't exist without lifting body research. This space plane and the shuttle shouldn't be derided for gliding into landing. Not using fuel while landing saves precious cargo capacity. If the main argument against them is that they can't land on the moon, I don't understand why a future craft couldn't both glide int…

> Not using fuel while landing saves precious cargo capacity Those wings are also a lot of mass, and hence take away from payload. In fact, propulsive landing always takes less mass than wings in the limit of large craft size. (You can see this by taking an equivalent limit, the limit of thin atmosphere; for sufficiently thin atmosphere, the amount of surface area you need to brake diverges but the amount of fuel to…

I won't argue with that, but that isn't true in the case of the X-37, which is why it glides into landing.

Elegance in engineering is fulfilling the requirements in the simplest, cheapest way possible.

Re: Unmanned U.S. Air Force space plane lands after secret, two-year mission

#100

Post by jjoonathan »

nradov wrote: post #79
tammer wrote: post #20

Surprised nobody's mentioned this possibility as it usually comes up re: the X-37B. Terrifying but I think not out of the question given the strategic potential of such a weapon. https://en.wikipedia.org/wiki/Kinetic_bombardment

Orbital kinetic bombardment is a silly concept suitable only for cheap sci-fi novels. There's no benefit in having kinetic weapons permanently positioned in orbit. The satellites would be easily tracked and vulnerable to ASAT weapons. They can't strike a target much faster than a ballistic missile launched from land or sea. And they would be much more expensive. Anything in orbit is out of reach of maintenance. It ta…

Assuming everyone lives, builds stuff, and maintains stuff at the bottom of the gravity well is an assumption well suited to the present day, but not to the setting of most cheap sci-fi novels.
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