New Space-X rocket is the most Kerbal rocket I've ever seen in real life

[LameLefty]

Not really a correction - I simply noted that it was part of the design. Cross-feed is only required when doing a maxium payload lift...and there are no flights anywhere near that capacity on the launch manifest so far. The first launch will be a test only (although I suspect they'll carry a Bigelow Aerospace station), the second is a relatively light payload.

Should be a wild ride to watch

Crossfeed isn't even being actively worked on at this point. It's on their technical roadmap but honestly they've got so much on their plate right now, the sources I've got access to indicate that it won't even be considered for actual implementation until they have 2 - 4 flights worth of data. Between the new stretched version of the base F9 (longer tanks, new thrust structure, provisions for landing legs on the first stage ...) , the Merlin 1D engine, ongoing Dragon production and design work for crewed Dragon, the base F9 Heavy (non-crossfeed version), and activation of the new pad at Vandenberg AFB, they have PLENTY of stuff to keep them very busy indeed.

My personal guess is that cross-feed will come into serious focus only when F9 wins a major U.S. NRO or DoD contract. They are just about the only real customer that needs that kind of performance to low- and medium-earth orbits. Honestly, SpaceX needs a higher-energy upper stage (LOX/LH2 or more likely LOX/methane) for the GEO market - they'd have a KILLER vehicle for the next generation of super-heavy commercial comsats being talked about.

[Kosmic Debris]

Crossfeed isn't even being actively worked on at this point.

Not my understanding from my single internal source, but I think we can agree that it's part of the design and they're actively selling it - regardless of the current readiness or level of effort. I don't disagree at all that they've got a lot of other irons in the fire - it's hard to imagine how well they appear to be managing not only the development but actual production. Certainly shaking up the market!

My personal guess is that cross-feed will come into serious focus only when F9 wins a major U.S. NRO or DoD contract.

They've won two from the USAF, with the potential for another 3...but that's out in 2015. Both development missions, but could be huge for them.

In the end, a lot of this is about a) designing for new capabilities and building on their credibility. They've got a long ways to go to get into the Delta/Atlas club of consistently reliable launches...and a misstep would have a huge impact on their continued success.

All good stuff :-)

[lammatt]

hm, excuse me,

see... im a chemistry graduate and my second degree was in the education field and i am not much into rocketry news, in short, i am pretty uninformed about aerospace engineering,

but my question is, why would they do a powered elanding instead of using parachute and airbags when i expect they do the same job in a more economical/environmental manner

[Jarnis]

SpaceX are cheating, they're using mechjeb on their rockets........

<<<<ducks before various bits of space craft are thrown at him by other forum members

Neil Armstrong used MechJeb (Apollo Guidance Computer).

Read Digital Apollo: Human and Machine in Spaceflight and you'll never babble about MechJeb again. That's how real astronauts do it, so that's how it should be done. That book sure cleared a lot of misconceptions *I* had about how Apollo era spacecraft were flown.

They actually tried fully manual moon landing in the sims. Astronauts crashed it every time. Even the famous "manual dodging of big boulders" on Apollo 11 wasn't really manual - it was automated, with landing target coordinates changed by the astronaut using the hand controller.

(and even SAS is partial automation - comparable to "ATT HOLD" mode of AGC, so don't cheer how you have l33t skillz by landing to the mun using just the SAS. Real manual landing is without SAS and for proper "Apollo" difficulty you should have asymmetrical fuel tanks that drain and move the center of gravity of the lander along the way...)

Real Astronauts fly the computer which flies the ship. Go MechJeb!

[Tiron]

Neil Armstrong used MechJeb (Apollo Guidance Computer).

Read Digital Apollo: Human and Machine in Spaceflight and you'll never babble about MechJeb again. That's how real astronauts do it, so that's how it should be done. That book sure cleared a lot of misconceptions *I* had about how Apollo era spacecraft were flown.

They actually tried fully manual moon landing in the sims. Astronauts crashed it every time. Even the famous "manual dodging of big boulders" on Apollo 11 wasn't really manual - it was automated, with landing target coordinates changed by the astronaut using the hand controller.

(and even SAS is partial automation - comparable to "ATT HOLD" mode of AGC, so don't cheer how you have l33t skillz by landing to the mun using just the SAS. Real manual landing is without SAS and for proper "Apollo" difficulty you should have asymmetrical fuel tanks that drain and move the center of gravity of the lander along the way...)

Real Astronauts fly the computer which flies the ship. Go MechJeb!

Yeah, it's called 'Fly by Wire' in the Aircraft Industry.

Originally invented for Jet Fighters because it allowed them to use designs that are actually aerodynamically unstable, and thus far more maneuverable. With Negative stability, it's already trying to turn in any direction it can get the tiniest start in, and the only reason it doesn't is the computer making constant adjustments to keep it flying straight. So when you actually command a maneuver of some kind, it pretty much literally LEAPS into it. As opposed to a plane with Positive Stability(which you have to drag kicking and screaming into the maneuver) or Neutral Stability (which just sits there unresisting as you move it around).

But on ANY plane with fly-by-wire, you're not actually in control of anything. Your inputs just tell the computer what you want it to do, and it figures out how to accomplish that and carries it out (within limits, in most designs). The F-16 for example. The original version of the F-16's Side-Stick didn't actually move, at all. (I guess it uses strain sensors or something?) The pilots had tons of problems with that, so it was modified to have an EXTREMELY small amount of play in it. I also gather from things I've read that the computers actually limit the maneuverability on it, and that there's some kind of a toggle that can set the limit to either a higher or lower setting as desired. I forget the exact details and I'm too tired to look for them right now. Sorry

Edited August 16, 2013 by Tiron

[camulus777]

Well its cool that companies are proving that privet enterprise can do it cheaper and better then government. It's amazing what you can do if you put your wallet to it

[Ralathon]

hm, excuse me,

see... im a chemistry graduate and my second degree was in the education field and i am not much into rocketry news, in short, i am pretty uninformed about aerospace engineering,

but my question is, why would they do a powered elanding instead of using parachute and airbags when i expect they do the same job in a more economical/environmental manner

Well, your expectation is wrong then

The first stage of the Falcon 9 is still really heavy when it is empty, 19 tons of empty weight according to the table at the bottom of this. You'll need some really big and heavy chutes if you want to bring that down to a safe velocity. For example, the chutes on the shuttle SRB's weighed 2.5 tons and those STILL hit the water at 23m/s. Admittedly, those are quite a bit heavier than the Falcon 9 S1 but it gives you an idea of how big and heavy this'll get.

Don't forget that a rocket stage is quite fragile, you don't want to hit those engines too hard. They aren't going to survive a fast landing followed by a bath in salty water like the boosters. So you need some way to give them a soft landing. And if you're going to bring fuel for that you might as well scrap the chutes and just make the entire descent powered.

[sojourner]

hm, excuse me,

see... im a chemistry graduate and my second degree was in the education field and i am not much into rocketry news, in short, i am pretty uninformed about aerospace engineering,

but my question is, why would they do a powered elanding instead of using parachute and airbags when i expect they do the same job in a more economical/environmental manner

It's already been talked about in this thread. Look back a few pages.

[magnemoe]

Well, your expectation is wrong then

The first stage of the Falcon 9 is still really heavy when it is empty, 19 tons of empty weight according to the table at the bottom of this. You'll need some really big and heavy chutes if you want to bring that down to a safe velocity. For example, the chutes on the shuttle SRB's weighed 2.5 tons and those STILL hit the water at 23m/s. Admittedly, those are quite a bit heavier than the Falcon 9 S1 but it gives you an idea of how big and heavy this'll get.

Don't forget that a rocket stage is quite fragile, you don't want to hit those engines too hard. They aren't going to survive a fast landing followed by a bath in salty water like the boosters. So you need some way to give them a soft landing. And if you're going to bring fuel for that you might as well scrap the chutes and just make the entire descent powered.

Yes, this is also true in KSP, try landing heavy stuff with parachutes and watch the effect, remember my 45 ton Eve lander, used two braking and 12 main parachutes, the braking ones was just ripped off while the main ones disintegrated the lander in an spectacular fashion.

In real world we also have wind, landing the high first stage with parachutes in any wind would not work well while its far easier using gimbaled engines and rcs.

[magnemoe]

Fair enough. But skydivers don't tend to have triple-redundancy on their parachutes - maybe a reserve in case the first fails to deploy, but even the Orion uses a triple-chute system like they did in the Apollo days. It can make it down on two, or even one - but you're tripling that weight for safety.

And I think the heavier your descent payload, the greater your need for that redundancy. Not because it falls faster (it obviously doesn't), but strictly for structural reasons. That's why it's not simply a matter of scaling it relative to a skydiver. [EDIT: Ninja'd by andrewas...]

At any rate, I didn't want to digress, as I did agree with the underlying and more relevant point Koshelennkov was making - that being, such mass is better spent on fuel, which can make a descent as effective and likely more economical in terms of usage of that mass.

An system with multiple independent parachutes is an cheap safety feature, its not much heavier than one large and increase safety a lot.

They could do the landing as we do in KSP, parachutes and an short burn to reduce speed just before landing, however have fun trying to land the high first stage in any sort of wind, yes you could cut parachutes at 10 meters but you would still have an 2-6 m/s sideway movement.

[Jarnis]

Why not use parachutes?

Same reason why no passenger planes use braking parachutes any more (there actually used to be a few in the 1950s that did...). Parachutes are extremely finicky to make and pack (and repack), needlessly complicating and delaying the turnaround for next flight. SpaceX is aiming for "Fuel up, stack up, apply payload, fly again". Yes, in the real world the turnaround time will probably still be weeks - it takes easily 4-6 weeks to integrate a rocket at the launch site from pre-built stages and prepared payload and obviously if you are reusing previously flown hardware, any checks and repairs have to be added to that. But why add something that definitely needs to be constantly repaired/replaced? Also parachutes are dead weight when going up. Coming down using the engines only adds the weight of the legs (which you'd need anyway) and needed fuel (which is incredibly small percentage of the total fuel).

Besides, chutes scale poorly when the size and weight of the payload increases (like, say, a large rocket stage).

[Tiron]

An system with multiple independent parachutes is an cheap safety feature, its not much heavier than one large and increase safety a lot.

They could do the landing as we do in KSP, parachutes and an short burn to reduce speed just before landing, however have fun trying to land the high first stage in any sort of wind, yes you could cut parachutes at 10 meters but you would still have an 2-6 m/s sideway movement.

Actually, that's EXACTLY how the Soyuz lands: Parachute descent, but fires some tiny solid rockets just before it touches down to slow it down a bit more. This is due to the fact it was designed to touch down on land, as opposed the old American capsule systems which were designed to touch down in the ocean.

And three parachutes doesn't necessarily mean triple redundancy: The old Apollo capsules used three but actually required two of them for a safe landing. The chances that two would fail on the same flight were considered pretty low, though (the same logic that skydivers rely on in only carrying a single reserve, which is generally lighter, more tightly packed, and doesn't slow them down as much as their main chute.) This worked out pretty well for NASA: the only Apollo flight I know of that had a parachute failure at all was 15: the crew reported all three inflated initially, and first noticed one of them had collapsed after the RCS fuel dump. It was later found to be missing shroud lines, cause unknown. (But speculated to be the RCS fuel dump)

Edit:

I suppose the advantage to doing it that way (3 chutes, 2 required, 1 pseudoreserve) is that you end up only having to carry 1.5 times as much parachute as you need, as opposed to 2 times if you use two that are both big enough to work with just one of them open.

Edited August 16, 2013 by Tiron

[camulus777]

Why not use parachutes?

Same reason why no passenger planes use braking parachutes any more (there actually used to be a few in the 1950s that did...). Parachutes are extremely finicky to make and pack (and repack), needlessly complicating and delaying the turnaround for next flight. SpaceX is aiming for "Fuel up, stack up, apply payload, fly again". Yes, in the real world the turnaround time will probably still be weeks - it takes easily 4-6 weeks to integrate a rocket at the launch site from pre-built stages and prepared payload and obviously if you are reusing previously flown hardware, any checks and repairs have to be added to that. But why add something that definitely needs to be constantly repaired/replaced? Also parachutes are dead weight when going up. Coming down using the engines only adds the weight of the legs (which you'd need anyway) and needed fuel (which is incredibly small percentage of the total fuel).

Besides, chutes scale poorly when the size and weight of the payload increases (like, say, a large rocket stage).[/QUOT

Corporations like Virgin and others are attempting to get away from the rocket idea. Its inefficient and costly, they are going for more winged craft that take off like every other plane and get into orbit that way. Space x its self proved that the idea was possible, these new balancing rockets are for interplanetary craft to mars and the moons of Jupiter. Or at least that is what the engineers are planning. In my opinion the first company to get to the moon on a budget of 100 million or less will be able to make some good money extracting He3 and other compounds that are expensive to synthesize here on Earth. There is money to be made in space its just not quite marketable yet, and tourism is not going to be paying for it all. Only a few people would be able to afford it.

[sojourner]

Stampede!!!!

LOL

[koshelenkovv]

Repacking parachutes is not reason for delay - one can use special packed parachute cartridges or something like that.

Even if SpaceX will not achieve success in spent stages recovery, they can use acquired methods and practice in the future to make soft-landing Dragons and Lunar/Martian spacecrafts.

It seems like they trying to be far-sighted. Falcon9 was designed to be human-rated, so they will not need to build another rocket. Soft-landing Dragon and stages will eliminate need to design absolutely another craft for landing on Moon, etc.

[camulus777]

Moon is easy, Mars not so much. It still takes to long to get there in even the best conditions, and then when you get there its not the nicest place to be.

[CatastrophicFailure]

Stampede!!!!

LOL

LOL if the rocket returning and landing on its tail isn't Kerbal, THAT surely was! KSC needs livestock!

[HeadHunter67]

Actually, that's EXACTLY how the Soyuz lands: Parachute descent, but fires some tiny solid rockets just before it touches down to slow it down a bit more. This is due to the fact it was designed to touch down on land, as opposed the old American capsule systems which were designed to touch down in the ocean.

To be fair, not every Soyuz landing is a good one - its safe operational history is only because they've used the same kind of craft for decades. I wonder how often they're able to reuse a Soyuz re-entry capsule - or how often the crew is injured.

[astropapi1]

Stampede!!!!

LOL

Loooool! why did they upload it as classified?

[Motokid600]

To be fair, not every Soyuz landing is a good one - its safe operational history is only because they've used the same kind of craft for decades. I wonder how often they're able to reuse a Soyuz re-entry capsule - or how often the crew is injured.

There is a documentary about the creater of Ultima. He bought a ride to the ISS on the Soyuz. Brillant flick. At the end they show the inside view when the capsule hits the ground. Oh..my..god. I swear its like a car crash. Doesn't look fun. I know now why each man gets a custom fitted seat. Scary violent impact.

Edited August 19, 2013 by Motokid600

[CatastrophicFailure]

There is a documentary about the creater of Ultima. He bought a ride to the ISS on the Soyuz. Brillant flick. At the end they show the inside view when the capsule hits the ground. Oh..my..god. I swear its like a car crash. Doesn't look fun. I know now why each man gets a custom fitted seat. Scary violent impact.

Have a link or name of the flick? Been searching youtube for interior footage of a landing & no dice.

And just for the record, not really a fair comparison between Soyuz & Dragon. The Soyuz was never intended to be reused while the dragon is designed with that in mind from the start.

[Dooz]

Now Lets make this in KSP

[Nibb31]

There is a documentary about the creater of Ultima. He bought a ride to the ISS on the Soyuz. Brillant flick. At the end they show the inside view when the capsule hits the ground. Oh..my..god. I swear its like a car crash. Doesn't look fun. I know now why each man gets a custom fitted seat. Scary violent impact.

Soyuz lands at 3m/s, which is equivalent to a 10km/h fender bender. With the crew strapped in an optimal position and suspended seats, its no worse than a hard landing in a airliner.

The seats and floor of the capsule are designed to collapse so that a 10m/s impact (which is what you get if you landed solely on the parachute) would still be survivable. If you get caught in a 30km/h car accident, properly braced and strapped in, you will be a bit shook up with a few bruises, but you will walk away alive.

Edited August 25, 2013 by Nibb31

[astropapi1]

RSA doesn't give a sh*t.

De-orbiting over land? Why not?!

[Jackissimus]

Musk boasts an eventual turnaround time from launch to launch of the re-usable first stages of 10 days.

Mind providing a link for this? Because I found it's just a couple of hours:

Musk told Popular Mechanics, â€ÂMultiple flights per day for first stage and side boosters. At least one flight per day for the upper stage.â€Â