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Comment Re:Space Ship One? (Score 3, Interesting) 113

Their design was kind of problematic. People naturally gravitate towards polybutadiene because of its use as a binder in solid rockets. But hybrids are not solids. Hybrids are great in most regards except for generally pathetic burn rates. Rather than consider other fuels, SS1 just used a typical solid rocket binder. One can compensate for the low burn rate, of course - usually by trying to increase the area by making many, smaller channels - this they did. But the more your propellant looks like swiss cheese, the more likely you are to have chunks break off as the rocket burns down. Which is exactly what happened on one flight, they had such a loud bang during the strike that the pilot thought his engine had exploded.

The proper solution is pointed to by research. Rather than polybutadiene the propellant should be something like paraffin or polyethylene. They melt at lower temperatures and become very fluid. The combustion basically whips up a "spray" off of the surface, making for very rapid combustion. With rapid combustion you don't have to "swiss cheeseify" your propellant. The polyethylene and the high melting point paraffins also are very strong and stable at room temperature.

Comment Re:Please put the word "space" in quotes (Score 3, Informative) 113

a feat that not even government space programs have achieved

Because they haven't seen fit to waste any money on it because it's such a meaningless endeavour. There's so little money in it, except for tourism, which government space programs (possibly excepting the Russians) have no interest in.

As a general rule, when governments shoot something up, they want it to stay up.

Comment Re:Please put the word "space" in quotes (Score 2) 113

But the public confuses space and orbit. To them they're synonymous. It is not technically incorrect to call it "reaching space", but it's also not wrong to point out that "reaching space" and "reaching orbit" are not even in the same ballpark.

Anyway, the oxidizer is HTP, so we can look forward to this company going bust shortly after they suffer from a catastrophic tank explosion - hopefully while nobody is around. Seriously, why did every other little suborbital rocket startup in the 1990s and 2000s suddenly decide that in contrast with the vast amount of evidence amassed earlier, HTP is in reality an easy, convenient, safe oxidizer choice? Because they can find household peroxide in their medicine cabinet and gee, it seems safe enough?

(It's not impossible to use HTP safely - for example, it's used for maneuvering in Soyuz - but it usually takes a number of explosions to get your process refined to the point that that doesn't happen any more)

In general, rocketry has pretty much well settled on the right general formula for liquids and hybrids: LOX (clean, absurdly cheap, relatively dense, low viscosity, stable and (by oxidizer standards) non-corrosive in the right conditions, and although cryogenic we've gotten good at dealing with that) burned with hydrogen or alkanes of varying lengths (depending on the desired balance between efficiency and temperature/density/power; they're clean, cheap, stable, low viscosity and readily vaporized, non-corrosive, etc) and optionally fine-grained aluminum if one can work it (up to 20% - cheap, rather clean, very stable, dense, and very energy-rich). Some of the alternatives under research may provide some benefits, and in certain particular situations there might be a need for "special cases" (for example, where hypergolics or monoprops are essential), but by and large for bulk "lifting" it's about refining designs, not propellant combinations.

Comment Re:Please put the word "space" in quotes (Score 4, Informative) 113

To put it another way: the Falcon 9 first stage has a loaded mass of 418 tonnes and an empty mass of 23 tonnes, or a ratio of 18,2 to 1. New Shepard has a loaded mass of 75 tonnes and an empty mass of 20,5 tonnes, or a ratio of 3,66 to 1. Noticing a bit of difference here? New Shepard has, proportionally, 5 times more mass to throw around toward making their landing easy. How easily do you think they could cut their spacecraft to 20% of its current weight and still land? And on top of that, they face far lower wind loadings and heat loadings to boot and have far less crossrange to deal with, making it that much easier on them.

Suborbital spaceflight is the special olympics of spaceflight.

Comment Re:Please put the word "space" in quotes (Score 4, Insightful) 113

Again: "from space" is not the same thing, or even close, to "from orbit". It's not the height that causes problems, it's the velocity. And more importantly than that, it's the extreme mass limitations that reaching that velocity imposes on your craft. With suborbital flight you can dedicate all the mass in the world to making the task as easy on yourself as possible.

Comment Please put the word "space" in quotes (Score 4, Interesting) 113

Flights that just pop up to the Karman line and back down are virtually nothing like flights that actually go to orbit. Even the X-15, which actually reached a quarter of orbital velocity, was far more like an orbital flight than a straight up/down jaunt.

The Karman line is only 1/3rd to 1/4 of the way to proper orbital altitude. And the energy required to achieve orbital altitude is only a tiny fraction of that required to reach orbital velocity. And the rocket equation means that the faster you want to go, the exponentially more mass it takes. These little up-down jaunts do nothing except to confuse the general public into thinking that they're doing something similar to orbital spaceflight.

Comment Re:This is why ISIS wins (Score 5, Informative) 485

It's really not, at least among the major players. In the north (where the most relevant fronts are, even if there is still lots of random fighting elsewhere) you have Daesh in the east, the YPG (kurdish "Peoples' Defense Units") to the north of them, and JaF (Jaish al-Fatah, "Army of Conquest")/FSA alliance in the center (down to just north of Hama, and edging into Latakia by the Turkish border). The FSA has many different brigades but they're all pretty unified by wanting to fight Assad and Daesh and being composed of members who explicitly didn't join the (formerly much more powerful) Islamist militias. JaF is comprised of a number of militias, mostly islamist, the two most powerful being Ahrar ash-Sham ("Supporters of the Levant") and Jabhat al-Nusra ("The Support Front for the People of the Levant").

Let's break down the players.

The YPG, opposed by Turkey (out of fear of links to the PKK), controls a long strip along Turkey's northeast border, as well as a couple of pockets west of there. They have a long border with Daesh territory and fight almost exclusively against Daesh (even though there's one or two Assad pockets within their territory). Recently they've launched a major anti-Daesh campaign, using US-supplied weapons, in an alliance with Arab anti-Daesh forces, under the banner of Syrian Democratic Forces. So far it seems to be progressing well.

Daesh (aka IS/ISIS/IL) is, of course, Daesh. A group of Islamists so radical that even al-Qaeda thinks they're nuts. That said, it should be reiterated that not everyone who fights for them shares their ideology. They literally do run what is effectively a state, with locally sourced money (based around oil pumping, refining with truck-mounted mini-refineries, and sales - both domestic, to Turkey (black market), and even to Assad, who they're vehemently against. This money funds a militia far larger than their ideological base, often made up of the poor and displaced in the conflict who need the work. That said, literally armed entitity who's not part of Daesh in this conflict is an enemy of Daesh, so it's hard to imagine them surviving in the long run.

The FSA was once the largest fighting force in early post-revolution Syria, but atrophied to a lack of financing and weaponry, becoming a paper tiger. Since 2014 however a joint US/Saudi/Turkey program under the auspices of the CIA (not to be confused with the gigantic-failure Pentagon program) has funnelled them a basically unlimited supply of TOWs, which they've been making good use of - their kill rate is reportedly about 6 out of 7 fired. Their numbers have increased since then. So far they seem to have managed their assets quite well, with reports stating that only 2 (some say 4) have fallen into other hands (Jabhat al-Nusra), and they seem to have used them. FSA works closely with JaF but is not part of the alliance itself.

Jaish al-Fatah is as mentioned a coalition, largely Islamist, although its individual members vary significantly. Let's go into the two biggest ones.

Ahrar ash-Sham can be thought of as sort of like the Muslim Brotherhood: Islamist, supporting sharia, but locally focused. Saudi Arabia and Qatar seem to have this group as their favored dog in the game.

Jabhat al-Nusra is a branch of al-Qaeda operating in Syria. Strangely despite this they haven't been behaving very much like al-Qaeda usually does, and they've been a very effective force against both Assad and Daesh. While they still take part in things like suicide bombings and human shields, they have a policy of not taking any anti-western activity and have worked hard to try to not engender local resentment, such as not imposing sharia on Christian towns. Qatar has been reportedly working to try to get them to break with al-Qaeda, but so far this campaign has not yielded any fruit. A large chunk of al-Nusra's fighters are foreign volunteers attracted by the name and they would risk losing them if they were to break with al-Qaeda.

JaF is really tricky on how one should deal with it. Ahrar ash-Sham is most likely no threat to the west, and one hopes that it doesn't evolve into something that could be. Jabhat al-Nusra currently has taken a strategy of non-hostility activities to the west... but they're still al-Qaeda, and it would be pretty stupid to not consider the possibility that this might change in the future. The coalition currently does not attack them, preferring to focus on the much more significant threat posed by Daesh, who JaN also fights. Then there's confusing groups. For example, after Daesh put out a statement taking credit for and praising the Paris attacks. As a counter, many Syrian militias signed onto a statement condemning the Paris attacks as brutal and unjustifiable war crimes. al-Nusra issued no statement supporting or condemning them. But another JaF member, Jaish al-Islam (Army of Islam), did sign onto the condemnation statement. Yet in the past the head of JaI has praised bin Laden. So how do you interpret a group like that?

In short: there are many parties in the conflict. Some of them are pretty reliable and trustworthy. Others are Clearly Bad News(TM). Others are more ambiguous.

One can act accordingly.

Comment Re:Russia won't retaliate (Score 4, Informative) 485

Oh hey, speak of the devil, they just released a video of the hitting of the helicopter: link "Hard landing" my arse.

They'd really be nowhere today if it wasn't for those TOWs. They film every attack - footage and return of the tubes is apparently part of the deal to get more, to prevent them from stockpiling them or transferring them to other militias, so there's a couple new videos put out every day. Saudi Arabia reportedly purchased 13k of them from the US which it routes through Turkey in batches of a couple hundred at a time.

Comment Re:Russia won't retaliate (Score 4, Interesting) 485

I don't think Russia is so much of an idiot as to give the Kurds anti-aircraft systems. Because Turkey would respond by giving the FSA anti-aircraft systems. Which would be far more devastating due to how close the Russian airbase near Latakia is to opposition troops and how Russia's been focusing so much on close air support, as well as the ratios of assets in the region that could be employed if necessary (Turkey and the other coalition states have far, far more)

Russia's also at real risk of facing a heavy dose of irony. As the battle front has spread deeper into Latakia (yes, Russia/Iran/Hezbollah/Assad has lost ground in Assad's heartland since the Russian/Iranian surge) it's increasingly violent in Jabal al-Turkuman, aka the Turkman Mountains, aka an area to a large indigenous Turkic population. The Russian strikes there have stirred up anger in Turkey (probably no doubt a contributor to Turkey being a bit more trigger-happy on their antiaircraft missiles than usual), and in recent days pictures have started emerging of members of far-right parties in Turkeys that have crossed over to Syria and taken up arms. This has the potential to involve into a mirror of the situation in Donbas.

BTW, and back to the original topic - why are so few people covering the helicopter downing in Syria? Look it up: one of the helicopters in Latakia on search and rescue mission for the plane crew went down. The rebels say that they hit it with a TOW. Russia says that it underwent a "hard landing", but that the crew is okay.

Oh, and we still have Israel continuing to be a wildcard, having launched several strikes inside Syria again just the other day, in the heels of last week's attack on the Damascus airport. They seem determined to stop Iran and Russia from transferring advanced weapons to Hezbollah at any cost.

I've got a bad feeling about this.