The "Real Aerospace" Thread

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Arioch
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Re: The "Real Aerospace" Thread

Post by Arioch »

Also, NASA doesn't build rockets and never has. Lockheed-Martin and Northrop-Grumman and Boeing/Rockwell do, on NASA's behalf. The space industry has always been in the hands of private industry, and there have always been accidents and screw ups; the only difference now is that they can be blamed on corporate managers instead of NASA managers.

After every NASA accident, there was always some talking head saying that NASA was incompetent and the space program should be privatized; now the other group of idiots get to say the reverse.

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Re: The "Real Aerospace" Thread

Post by Senanthes »

Unfortunately, accidents happen under extreme conditions at the slightest provocation, and aerospace flight certainly qualifies as extreme conditions...

Which doesn't make it any less of a tragedy. :(

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Re: The "Real Aerospace" Thread

Post by Grayhome »

So that is the general feel this thread is going for? Orbital Science got a 40+ soviet constructed piece of junk out of storage, used it, it explodes, and it's just a common, run of the mill error that NASA makes all the time?

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Re: The "Real Aerospace" Thread

Post by icekatze »

hi hi

Considering that the Soviets made some damn fine engines, it is not hard to imagine why a company might want to use some of them, considering how hard it is to get rocket engines in general.

Some statistics. Claude Lafleur's Spacecraft Encyclopedia, 2014
Russia - 2975 successful - 203 failures - 93.60% success rate
USA - 1435 successful - 152 failures - 90.42% success rate
Europe - 215 successful - 17 failures - 91.7% success rate
China - 183 successful - 17 failures - 91.5% success rate
Japan - 79 successful - 14 failures - 84.85% success rate
India - 29 successful - 10 failures - 73.75% success rate

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Re: The "Real Aerospace" Thread

Post by Arioch »

And of course, the Soviets always accurately reported their failure rate...

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Re: The "Real Aerospace" Thread

Post by icekatze »

hi hi

It turns out that it is actually quite difficult to hide a failed rocket launch. They tend to be remarkably visible events. Considering that even in the very early days of their space program, their failures were actually documented and now widely known, including the first human casualties in space. Like Vladimir Mikhaylovich Komarov, who died in Soyuz 1 on re-entry, April 24th 1967. They may not have published everything at the time, but they did keep internal documents, and a lot of those were released after the Soviet Union collapsed.

When it comes to politics, 2+2 can equal 6, but when you're trying to go to space, 2+2 has to equal 4. It's not like they could just pretend their failures didn't happen and succeed through the power of ignorance. Ignorance may produce hot air, but it doesn't produce delta v. :P

Even if we just look at the post cold war world, there is also still no way to reasonably hide a rocket failure, since the people who are trying to put a spacecraft into orbit generally want to know where it went.

The information is hardly classified. You can look for yourself if you'd like.

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Re: The "Real Aerospace" Thread

Post by Alexandr Koori »

In time of Glasnost' madness 1988-1993 many documents was reclassified. And all of spacecraft industry, as I know. Do you want to read about incident on launch R-16 in 1960? Nobody knows about it before end of 80-th. Now -at your pleasure. Do you want to see drawings of Buran? At your pleasure.

This is just most significant examples.

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Re: The "Real Aerospace" Thread

Post by icekatze »

hi hi

The Defense Support Program, replaced the flawed Missile Defense Alarm System in 1970, and has been keeping track of unannounced missile launches ever since. From Iraqi short range tactical missiles, to North Korea's ballistic missile tests.

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Re: The "Real Aerospace" Thread

Post by Nemo »

Hard to keep secret, like the N1 program. Which didn't even exist until 1989. No, before that it was just a fake out to the US to make them THINK there was a space race going on. Hardy har, foolish Yankees.

Granted, the Soyuz has a long and fairly reliable history. The US ultimately opted for the technically more complex space shuttle, which saw its share of failures. Had the Soviets pursued the Buran, I imagine it would have faced many of the same issues, and each would have learned from the other. Presupposing they remained honest that is. Challenger and Columbia, Apollo 1, etc etc etc., due to the nature of the American system of politics these failures were loud and the causes widely disseminated. No one at the time learned anything from the Soviet failures, like the N1 or Proton rockets in development, because of their inability to face embarrassment. Whether we actually know the full truth remains an open question. Its difficult to prove a liar is not lying when asked to take his word for it.

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Re: The "Real Aerospace" Thread

Post by icekatze »

hi hi

The statistics I'm using are only taking into account rocket launches that were attempted. If you look at the statistics, most of the rockets with 100% success rates are also rockets that have single digit launch attempts. Going to space today is rocket science. People aren't just throwing these things together with a hammer and duct tape.

So yes, in the sense that even extremely minor defects and mistakes can ruin an entire launch, it is "run of the mill," to have rockets explode. Although that isn't the wording I would choose myself.

(My brother, who is an actual rocket scientist, had a lot to say about why the N1 failed. Layman's condensed summary though, there are good reasons why the US chose to use a smaller number of larger rocket motors, and good reasons why the Soviets could not overcome the not-insignificant engineering hurdles required to do so themselves.)

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Re: The "Real Aerospace" Thread

Post by Zakharra »

icekatze wrote:hi hi

Considering that the rocket industry hasn't been privatized, that is a strange claim to make. But I guess there is a lot of confusion over who is running what, how, and why.

I got the impression they meant more direct NASA control over the projects. As in the private companies build them, but NASA controls the funds and is in full charge of the project. No private companies doing their own thing involving the space industry. Yay. even more government control. /sigh

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Re: The "Real Aerospace" Thread

Post by icekatze »

hi hi

I wonder where they get these so called, "experts." It sounds like someone that is totally clueless about space travel in general. First of all, NASA controls the funds and is in overall control of Orbital Sciences' resupply mission, even if they decide not to insert their own managers into every level of the process, they are present during lift-off. Second of all, NASA does not own outer space, the USA does not own outer space, if the US government didn't want to let private companies go to space, they could just find someone else to carry their payloads, like Russia or Europe.

The AJ26 equipped Antares rocket had four prior successful launches before the fifth launch ended in failure, and Orbital Science's predecessor to the Antares, the Taurus, also suffered an unsuccessful launch in 2001, on the second stage.

On average, one out of every 16 orbital space launch attempts ends in failure. That rate of failure has been roughly steady for the last 40 years.


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Re: The "Real Aerospace" Thread

Post by Mr.Tucker »

Ok, since I'm an aerospace fan, and I have a few nagging questions, I though I would post them here, hoping someone with a better knowledge and inside info on space projects may answer them. If not then no worries :) .

First up: can anyone please explain the difference between a magnetic sail (or magsail) like the one proposed by Zubrin&Andrews and an electric sail? I know quite a bit about magsails, but E-sails are supposed to be a relativelly newly developed system. And they seem to work on the exact same basis, so how would they be different from the earlier magsails?

Second: why is a VASIMR drive considered to be better than an MPD (seem like the official line from NASA). The VASIMR can do both high thrust and high Isp, sure, but the MPD can do BOTH at the same time. And they have similar power requirements.

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Re: The "Real Aerospace" Thread

Post by Arioch »

Mr.Tucker wrote:First up: can anyone please explain the difference between a magnetic sail (or magsail) like the one proposed by Zubrin&Andrews and an electric sail? I know quite a bit about magsails, but E-sails are supposed to be a relativelly newly developed system. And they seem to work on the exact same basis, so how would they be different from the earlier magsails?
As I understand it, a magsail is a loop of wire through which a current is run, creating a magnetic field, while the E-sail is a set of straight wires radiating from a central point which are charged with electrons, creating a static electrical field but not a magnetic field. Both will deflect and derive momentum from the charged particles of the solar wind, but the magsail can also push against planetary magnetic fields, whereas the E-sail can't (and since planetary magnetic fields usually deflect the solar wind, an E-sail won't get much thrust at all inside a magnetic field). A magsail can also be used as a brake against the interstellar medium (if the magnetic field ionizes the hydrogen), which I don't think is true of an E-sail. The advantage of the E-sail would be that it's smaller and cheaper than the magsail, which requires the use of superconducting wire.
Mr.Tucker wrote:Second: why is a VASIMR drive considered to be better than an MPD (seem like the official line from NASA). The VASIMR can do both high thrust and high Isp, sure, but the MPD can do BOTH at the same time. And they have similar power requirements.
I'm not sure, but it looks like the VASIMR VX-200 currently in testing requires 200 kW, whereas proposed magnetoplasmadynamic thrusters require 600-1000 kW.

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Re: The "Real Aerospace" Thread

Post by Mr.Tucker »

I see. I guess superconducting cables of such lengh are still some way off. Its surprising though given that the entire ISS produces around 144 kw. You still need some kind of space reactor to operate even the lower powered VASIMR. Its' sad knowing that the Phoebus II NTR produced during the 60s produced 4000MW (yes, most of it was thermal, but that doesn't mean it can't be at least partially used).

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Re: The "Real Aerospace" Thread

Post by icekatze »

hi hi

I hate to be a spoil sport here, but VASIMR engines are magnetoplasmadynamic thrusters. Variable Specific Impulse Magnetoplasma Rocket.

There are lots of competing designs being built by various companies, and they all suffer from the power input problem. It is my understanding that one of the main benefits of the VASIMR design over many of the competing designs is that it doesn't use electrodes to generate the plasma, which allows them to magnetically shield the whole engine chamber, which prevents corrosion over time.

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Re: The "Real Aerospace" Thread

Post by Mr.Tucker »

You're not being a spoil-sport, you're being helpful :) . So they operate on similar principles, but with a different way to create the plasma (electrodes vs microwaves). Sounds about right. I guess VASIMR would work as an interim solution until material sciences can get better at building cathodes that don't evaporate. Though I still question the idea of buiding a drive you can't power. Then again, I question a lot of things NASA does these days.

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Re: The "Real Aerospace" Thread

Post by icekatze »

hi hi

I guess you have to look at "high thrust," in a relative manner. Compared to the ion engine on the Dawn spacecraft, which gets 90 milliNewtons of thrust, the Princeton MPDT got a whopping 12.5 Newtons of thrust at 200kW. That is even high when compared to the VASIMR's 5 Newtons at 200kW in high gear, but low compared to the VASIMR's 1000+ Newtons in low gear. When you compare it to the space shuttle solid rocket booster's 12,500 kiloNewtons of thrust, none of them seem very high thrust.

There is sort of an inherent tradeoff between thrust and exhaust velocity, and getting both is really hard to do.

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Re: The "Real Aerospace" Thread

Post by Mr.Tucker »

Yeah, I agree. I was refering to the ''High thrust'' relative to other ion/drives. I still do consider the Princeton MPD as superior to the VASIMR, since it can be used in a more flexible manner while being more economical. But yes, compared to other potential tech, like nuclear thermal or fusion, they are low thrust/high Isp with high mass power requirements. The only drive which could do both ''real'' high thrust and high Isp is the nuclear salt water....which is so problematic on so many fronts that it doen't really even need to be taken into consideration.

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