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SpaceX's New Spin on Falcon 9

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Re: SpaceX's New Spin on Falcon 9

#61

Post by kllrnohj »

FD3SA wrote: post #9

"It's about a 30% increase in performance, maybe a little more. What it does is it allows us to land the first stage for GTO missions on the drone ship." I am constantly blown away by SpaceX. This is an absurd level of improvement for an already mature, commercially successful rocket. If even 1% of the world's companies in other sectors worked this well, I can only imagine how much our quality of life would improve.…

> This is an absurd level of improvement for an already mature, commercially successful rocket.

What are you basing that on? And an absurd level of improvement can just as easily mean that V1 was just really bad, not that V2 is just that good.

I mean, the Merlin-1D has really good thrust to weight ratio, but the actual amount of thrust and the ISP at sea level is lacking compared to, say, the space shuttle's main engines (even with +30% the 1D is going to come short of 1,000 kN thurst, whereas the RS-25 on the shuttle was 1,860 kN).

It also runs on RP-1 which is a supply-constrained fuel choice that also has a max theoretical ISP that's lower than the ISP that the space shuttle's main engine actually achieved at sea level. And the RS-25's vacuum ISP is so far out of the 1D's reach it's not even funny. Not saying the RS-25 is particularly unique here, there are 17 liquid-fueled rocket engines that have an ISP over 400 in a vacuum, 9 of which also have more thrust than the 1D. The 1D by contrast has an ISP of 340 in a vacuum. 9 engines that have more thrust and more efficiency than the 1D. 9. But somehow Space-X is the one that blows you away?

So sure, it has good thrust to weight - at the cost of using a limited fuel, with low efficiency, and low total thrust. Wow that sure is worthy of just being blown away by absurd level of improvement

The one thing Space-X and Elon Musk do deserve credit on is they sure know how to market effectively. He is really, really good at making mundane tech sound amazing.

Re: SpaceX's New Spin on Falcon 9

#62

Post by stcredzero »

termain wrote: post #49
ChuckMcM wrote: post #47

Earlier quoted context omitted.

> Anyway, these are probably the most exciting times in > spaceflight since the 60s! Yes it is, and we get to use technology from the future this time :-). It is bittersweet for me, the opportunity lost to keep funding NASA at a reasonable level could have a lot of useful data in the 'bank' as it were, but by and large much of the stuff that makes what SpaceX does possible is relatively new. In particular the avionic…

"It is bittersweet for me, the opportunity lost to keep funding NASA at a reasonable level could have a lot of useful data in the 'bank' as it were, but by and large much of the stuff that makes what SpaceX does possible is relatively new." Minimally, the pintle engine technology came out of NASA work and I suspect much of their technical knowledge comes either directly or indirectly from NASA funding. " Clearly nobo…

Where there are engineers feeling oppressed, there is opportunity to disrupt!

Re: SpaceX's New Spin on Falcon 9

#63

Post by semi-extrinsic »

mikeash wrote: post #23
arikrak wrote: post #5

Earlier quoted context omitted.

That was their original plans for the shuttle. Not saying they won't be able to save money this time, but it's never that simple.

The Shuttle pushed the envelope in a dozen different ways and always operated right on the edge, which made it incredibly complicated and caused it to require extensive refurbishment after each flight. If you look at costs relative to constructing new launchers, reusing the Shuttle was quite cost effective. Cost per launch was in the neighborhood of $500 million, while the cost of building a new orbiter was in the ne…

The Shuttle's design was also complicated by the military who required it to have a huge 1000 nm cross range capability.

Re: SpaceX's New Spin on Falcon 9

#64

Post by stcredzero »

Tuna-Fish wrote: post #25
nickhalfasleep wrote: post #20

Earlier quoted context omitted.

I wonder if instead of letting the second stage burn up, they could dock them in space somewhere to serve as material and fluid storage. They might not work for long term cryogenic storage, but a ton of pure aluminum has to be worth something up there.

They launch to specific orbits desired by the customers. It might well be extremely expensive to move the second stage from these orbits to some common one where could dock.

If we could fuel tugs with material from off-planet, then it wouldn't be nearly as expensive to do this.

Re: SpaceX's New Spin on Falcon 9

#65

Post by mhandley »

justin66 wrote: post #33
martythemaniak wrote: post #8

Currently they have to throw away the rockets used for GTO missions (around half of them) and can only attempt landings on LEO missions such as the ISS resupplies. Given their last few landing attempts, it's pretty likely that they'll be able to land a rocket sometime this year, which means that starting next year they might be able to reuse all of their F9 Rockets. A lot of customers may not want to fly on a used ro…

> A lot of customers may not want to fly on a used rocket though (no one knows the risks) I am certain the insurers will be happy to take a crack at figuring out the risk. That matters a lot. Whether or not you "want to fly on a used rocket," if your company can purchase a flight and insurance on a used rocket for a lot less than it can purchase a flight and insurance on a new rocket, you might be obligated to try it…

Other than costs, another advantage of flying the first stage back is that they can be analyzed to see how all the components perform or wear, and the design improved based on the findings. It's harder to do that when you crash them into the Atlantic every time. Over time, this could mean that reusable rockets are actually more reliable than one-time use rockets, though only if you fly enough times to get the benefit of evolving the design.

Re: SpaceX's New Spin on Falcon 9

#66

Post by NamTaf »

toomuchtodo wrote: post #27
Tuna-Fish wrote: post #25

Earlier quoted context omitted.

They launch to specific orbits desired by the customers. It might well be extremely expensive to move the second stage from these orbits to some common one where could dock.

Yes, definitely cost prohibitive from a fuel perspective to change orbits, but the vehicle could be safed for future use. I do not have enough information as to whether though would be valuable unless Tesla as some way to produce fuel on-orbit for the waiting, safed second stages.

You'd have to keep boosting it where it is, which means it needs extra thrusters. Otherwise it'll just decay.

Also, changing orbits is expensive. Remember you need to change both height and angle, and the delta-V is huge.

Bringing them back down is almost certainly the easiest option.

Re: SpaceX's New Spin on Falcon 9

#67

Post by marktangotango »

kllrnohj wrote: post #61
FD3SA wrote: post #9

"It's about a 30% increase in performance, maybe a little more. What it does is it allows us to land the first stage for GTO missions on the drone ship." I am constantly blown away by SpaceX. This is an absurd level of improvement for an already mature, commercially successful rocket. If even 1% of the world's companies in other sectors worked this well, I can only imagine how much our quality of life would improve.…

> This is an absurd level of improvement for an already mature, commercially successful rocket. What are you basing that on? And an absurd level of improvement can just as easily mean that V1 was just really bad, not that V2 is just that good. I mean, the Merlin-1D has really good thrust to weight ratio, but the actual amount of thrust and the ISP at sea level is lacking compared to, say, the space shuttle's main eng…

To bad people down voted you without commenting on why. Here's what I think:

>>I mean, the Merlin-1D has really good thrust to weight ratio, but the actual amount of thrust and the ISP at sea level is lacking compared to, say, the space shuttle's main engines (even with +30% the 1D is going to come short of 1,000 kN thurst, whereas the RS-25 on the shuttle was 1,860 kN).

The Saturn's F1 engine had an even lower Isp, and was also KeroLox. Your focus on Isp is a bit misguided. Sure the SSME's have a stellar Isp, but guess what? The shuttle solid rocket boosters had a terrible Isp (Shuttle basically ran the RS-25 at lift off only to verify they'd start. They weren't throttled up until well into flight). When it comes to hauling millions of pounds off the launch pad, past the tower, Isp is not what you want. You want mass expelled at a tremendous rate. In other words, why not use electric ion engines with >2000 Isp for the first stage? Thrust to weight matters on lift off is why.

Re: SpaceX's New Spin on Falcon 9

#68

Post by remarkEon »

thelambentonion wrote: post #41
FD3SA wrote: post #9

"It's about a 30% increase in performance, maybe a little more. What it does is it allows us to land the first stage for GTO missions on the drone ship." I am constantly blown away by SpaceX. This is an absurd level of improvement for an already mature, commercially successful rocket. If even 1% of the world's companies in other sectors worked this well, I can only imagine how much our quality of life would improve.…

Disclaimer: I work in the space industry for one of SpaceX's competitors. None of my work is in competition with SpaceX (totally different systems), but it bears mentioning. I've also never worked for SpaceX, so a lot of what I'm saying here is opinion and hearsay. SpaceX does excellent work, and has an amazing track record for such a young space company. That being said, it's important to highlight that the 'absurd…

SpaceX takes that concept and turns it up to 11, expecting people to eat, breathe, and live their jobs. The last thing I would want is a firm dedicated to propagating these ideals.

On the other hand, if that's what you love it starts to not feel like work. In my experience getting that the match right is super difficult but perhaps that's what SpaceX is aiming for - not really looking for employees but members.

Re: SpaceX's New Spin on Falcon 9

#69

Post by darkmighty »

justin66 wrote: post #60
darkmighty wrote: post #35

Earlier quoted context omitted.

It's not a straightforward insurance matter since many many applications are time critical. If a rocket blows up they may need many more years until a replacement cargo can be manufactured, fitted into the launch schedule, etc. The coverage for that ( specially opportunity costs, which are hard to measure anyway) might be too high, making the insurance premium larger than the gain provided by reusability. I'd believe…

> It's not a straightforward insurance matter since many many applications are time critical. If you can put a dollar figure on the potential time loss, it's still a pretty straightforward matter. If you're flying with a "we must get this in orbit ASAP or the world will catch on fire" priority then, eventually, one will probably pay more for that. (the government will contract out a series of flights so it will play…

Being timely is pretty important in the satellite business, there are things like communication licenses which expire.

It may not seem like it, but launch costs are still only a fraction of the total system cost. Ground for example infrastructure is more expansive by a large factor. Even the sat manufacturing costs overshadow launch costs for most systems. That's why customers might prefer safety until reliability is proven. Cutting corners on launch can jeopardize the whole system.

Re: SpaceX's New Spin on Falcon 9

#70

Post by avmich »

darkmighty wrote: post #69
justin66 wrote: post #60

Earlier quoted context omitted.

> It's not a straightforward insurance matter since many many applications are time critical. If you can put a dollar figure on the potential time loss, it's still a pretty straightforward matter. If you're flying with a "we must get this in orbit ASAP or the world will catch on fire" priority then, eventually, one will probably pay more for that. (the government will contract out a series of flights so it will play…

Being timely is pretty important in the satellite business, there are things like communication licenses which expire. It may not seem like it, but launch costs are still only a fraction of the total system cost. Ground for example infrastructure is more expansive by a large factor. Even the sat manufacturing costs overshadow launch costs for most systems. That's why customers might prefer safety until reliability is…

The fact that payloads are so expensive is partially caused by the launches being so expensive, so reducing the launch price tag will cause reduction in payload costs.
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