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Experimental USAF space plane breaks record for orbital spaceflight

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Re: Experimental USAF space plane breaks record for orbital spaceflight

#81

Post by RobertoG »

ggm wrote: post #80
jandrese wrote: post #36

Earlier quoted context omitted.

https://www.military.com/daily-news/2019/07/23/former-secaf-... Long term heat management hardware for space electronics. Among other things no doubt.

"I think it creates more misconceptions about what the mission of the X-37B is and could lead to more international concerns that it's some type of weapons platform," Weeden said. "I think that works against U.S. interests because it will create more diplomatic problems for the U.S. when it tries to point out Russian and Chinese 'unusual behavior in space' and push for discussions on space norms of behavior." In shor…

>>"Like the Soviets believing in US first strike intent."

the soviets? We are really going back, aren't we?

Re: Experimental USAF space plane breaks record for orbital spaceflight

#82

Post by raducu »

walrus01 wrote: post #20
Tuxer wrote: post #19

Earlier quoted context omitted.

Space isn't like a highway where you can move from A to B at minimal expense. Switching orbits, both orbit heights but mainly orbit inclinations, comes at a very high delta-V expense and therefore propellant expense, which this craft simply doesn't have the volume to hold. This cannot shuttle between LEO stations and switch orbits to imitate multiple observation sats unless those sats and stations are very close in t…

people who haven't played kerbal space program (with mechjeb for data) usually don't fully understand how expensive, in terms of delta V, a large inclination change maneuver is.

I think the idea is that you plunge into the atmosphere, use lift to perform the orbital inclination change and then you raise your periapsis again.

I think you only need very little delta V to plunge back into the atmosphere from LEO.

The question is how much lift vs drag + delta V to lower and the raise you periapsis.

I think the space shuttle only had about 250m/s delta v once the yellow tank was exhausted, so those 250 m/s were enogh to complete both rasing the periapsis and then lowering it to de-orbit.

Think of a space-glider with one tip of its wings pointed straight down and the other straight up, if it has very little drag and a lot of lift, it could use its wings to maneuver north-south, change its orbital inclination, then when it gets out of the atmosphere again, once it reaches apoapsis it will spend some fuel to raise its periapsis again above the atmosphere, but KSP intuition is that if drag is low enough and lift is high enough, it could be better than to do an inclination change in vacuum.

Re: Experimental USAF space plane breaks record for orbital spaceflight

#83

Post by moonbug »

scarecrowbob wrote: post #34
kanox wrote: post #22

> breaks record of orbital spaceflight It broke it's own record of "time-in-orbit" and as far as spaceflight records go this is one of the least relevant. Once a spacecraft gets to orbit it is very easy to stay there almost indefinitely. Hell, the ISS breaks the record for "continuous habitation in orbit" every day.

Man, if you wanna get points in Tony Hawk Pro Skater, you gotta land the trick. Same thing... I don't think the ISS is gonna land that trick, as far as I know... I'd be stoked to find out I'm wrong about that, though.

What?

Re: Experimental USAF space plane breaks record for orbital spaceflight

#84

Post by TeMPOraL »

riffraff wrote: post #79
thorum wrote: post #41

I'm mainly surprised that we have reusable space planes at all. You'd think that would get more attention.

this still gets launched with a rocket, it's basically a very small unmanned space shuttle, so it's not as "cool" as, say, something that goes to orbit from the ground on its own.

Are single-stage to orbit (SSTO) spaceplanes even possible on Earth with current chemical rockets? They're a PITA to build in Kerbal Space Program, and there the universe is 1/10 the size of the real one (albeit with the same gravitational acceleration).

Re: Experimental USAF space plane breaks record for orbital spaceflight

#85

Post by TeMPOraL »

nwallin wrote: post #72
Phlarp wrote: post #59

Earlier quoted context omitted.

It uses an oblong orbit to gain a small window where the next orbit cannot be perfectly predicted by an adversary that can only watch half the sky. You can't gain delta-v by inducing additional drag on the craft.

If a spacecraft is traveling at 4,000 m/s and it plows headlong into a planet, it has gained 4,000 m/s of delta v. Delta v a measurement of a vector, not a scalar. The fact that its kinetic energy with respect to Earth is decreasing does not mean it isn't gaining delta v. In addition to the obvious (lowering your apogee) you can also use this delta v to change your inclination. It's not "free" of course- you need to…

> If a spacecraft is traveling at 4,000 m/s and it plows headlong into a planet, it has gained 4,000 m/s of delta v.

Yes and no. You've changed your velocity by 4km/s. You didn't gain usable ∆v, and you've just lost your spacecraft.

∆v means few related things. One, the amount of velocity change your mission plan requires. Second, the velocity change your craft is capable of using its own propulsion. Say you're plotting Mars orbit insertion. It requires (via [0]) 1.5 km/s ∆v. But you're a cheater, and decided to use aerobraking to bleed off (guessing a number) 1km/s of that velocity. This means you can complete this maneuver with a craft that only has 500m/s ∆v at the point of insertion. This does not mean the craft has gained ∆v.

--

[0] - https://www.reddit.com/r/space/comments/29cxi6/i_made_a_delt...

Re: Experimental USAF space plane breaks record for orbital spaceflight

#86

Post by [deleted] »

pletnes wrote: post #64
Phlarp wrote: post #59

Earlier quoted context omitted.

It uses an oblong orbit to gain a small window where the next orbit cannot be perfectly predicted by an adversary that can only watch half the sky. You can't gain delta-v by inducing additional drag on the craft.

You can certainly get delta-v with drag. You’ll keep bleeding energy from orbital (kinetic plus potential) to atmospheric heat, but that’s an entirely different thing.

[deleted]

Re: Experimental USAF space plane breaks record for orbital spaceflight

#87

Post by TeMPOraL »

therein wrote: post #60
raverbashing wrote: post #42

Earlier quoted context omitted.

Yes, orbital mechanics are very non-intuitive. Thinking "you're in space so can go anywhere" makes as much sense as thinking it's easy to go from Canada to the top of the Everest just because they're both on land.

Definitely, and in fact that's probably the first epiphany one reaches when one starts playing KSP.

Yup. You learn that you can easily go anywhere you want on a curved line, as long as you're willing to wait long enough. But making that line point towards where you want to go is a stupidly fuel-expensive process.

Re: Experimental USAF space plane breaks record for orbital spaceflight

#88

Post by vinay427 »

moonbug wrote: post #83
scarecrowbob wrote: post #34

Earlier quoted context omitted.

Man, if you wanna get points in Tony Hawk Pro Skater, you gotta land the trick. Same thing... I don't think the ISS is gonna land that trick, as far as I know... I'd be stoked to find out I'm wrong about that, though.

What?

I believe they're saying that the requirement of landing after staying in space for a long period of time should constitute a new record, and that they would be excited to learn about plans to land the ISS back on Earth in some capacity as this would place the ISS in the running for this record.

Re: Experimental USAF space plane breaks record for orbital spaceflight

#89

Post by TeMPOraL »

egdod wrote: post #23
walrus01 wrote: post #20

Earlier quoted context omitted.

people who haven't played kerbal space program (with mechjeb for data) usually don't fully understand how expensive, in terms of delta V, a large inclination change maneuver is.

I have so far resisted mechjeb (and other mods). Should I give it a try?

Mechjeb can help you with the boring parts. First couple dozen launches or orbital intercepts are super-fun. But once your goals shift from "let's land on the Mun" to "let's send a 250 ton ship to Duna", assembling it in orbit from a dozen launches starts to feel like a chore.

Re: Experimental USAF space plane breaks record for orbital spaceflight

#90

Post by TeMPOraL »

bigiain wrote: post #48
nine_k wrote: post #35

Earlier quoted context omitted.

This kind of sudden malfunction, along with acceleration not due to firing of any engines, would be a signal for the self-destruction device, likely chemically powered (explosive) and mechanically actuated. It would be sure to shatter the interesting electronic parts, burning or detonating any remaining fuel for bonus points.

I suspect the arguments about how much launch mass to devote to self destruct explosive and mechanism - compared to useful payload or manoeuvring propellant - would be interesting to see...

I suppose your self-destruct mechanism could be "aim retrograde and burn all remaining propellant". Might not turn out well for a spaceplane that latched onto such satellite.
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