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Space X 2nd stage recovery
On 4/19/2018 6:26 PM, Fred J. McCall wrote:
JF Mezei wrote on Thu, 19 Apr 2018 18:07:43 -0400: On 2018-04-19 16:20, David Spain wrote: Yes I agree. I suspect they are using it mainly for learning curve rather than practical economics, with BFR looming. Could balloons be used for landing cargo on Mars? (yeah, they would need to be huge ballons due to low atmosphere pressure). Only part way. You could use a balloon (or ballute) to increase cross sectional area to increase drag for aerobraking, but you're not going to actually get enough lift to land anything that way. There was a 'balloon/bouncy house' solution where the balloon(s) expanded around the payload which then aerobraked and was simply allowed to strike the surface. This only works for light payloads and I don't know if they ever tried it. Fred this was tried at least once I can remember. The first Mars rovers (Spirit & Opportunity) were light enough that inflated balloons where used to bounce land them on the surface of Mars after parachute. The follow-on rover Curiosity was too heavy for that approach and used the sky-crane retro-rocket approach after parachute. Dave |
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Space X 2nd stage recovery
"Jeff Findley" wrote in message
... In article , says... "JF Mezei" wrote in message news On 2018-04-17 20:05, Jeff Findley wrote: In article , says... https://www.space.com/40313-spacex-r...y-balloon.html By "party balloon" are we talking helium or Hydrogen filled balloons that will "lift" the stage to slow its descent? (and I assume provide drag initially). I'm guessing nitrogen myself. I don't think lift is nearly as important at this point is as drag over as large a surface area as you can manage. I heard helium, because while lift isn't important, mass most certainly is. And at the same volume and pressure, helium masses less than nitrogen. The mass of the molecule doesn't enter into the ideal gas law: P*V = N*R*T Jeff Fair point. And I believe they already have helium tanks on board, just use those as part of the supply. |
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Space X 2nd stage recovery
JF Mezei wrote on Mon, 23 Apr 2018
14:20:01 -0400: On 2018-04-22 19:37, Greg (Strider) Moore wrote: Fair point. And I believe they already have helium tanks on board, just use those as part of the supply. In terms of mass, wouldn't the mass of the balloon(s) be far more significant than that of the gas used to fill it/them? That depends on whether it's intended to just be a big, draggy bag or they're going to try to do something like a paraglider ballute. How heavy would the fabric need to be to survive re-entry? Again, it rather depends on just how they plan to do it, which we don't know. Or would they go with lighter "disposable" material where on balloon does initial slowing down before re-entry interface (where it burns up) and after it, another baloon is deployed do to the drag/lift in denser atmosphere? Go read the original article again. That's one thing we know they are NOT doing from what Musk said. -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw |
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Space X 2nd stage recovery
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Space X 2nd stage recovery
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Space X 2nd stage recovery
On 4/24/2018 7:10 AM, Jeff Findley wrote:
I'm glad they're working on upper stage recovery. My guess is that BFR/BFS will take a bit longer than Elon's aspirational schedule products. As such, Falcon 9 and Falcon Heavy will remain the workhorses of SpaceX for many years to come. Anything they can do to cut their costs increases the cash they can funnel into BFR/BFS development. I am of the opinion that the existing F9 and F9H architectures will be (crew-wise) underutilized. In a perfect world, a "white knight" would step forward and say, "Look we love what you have flying already. And we want to build our own (crewed) space program around it." That WK *could* be NASA, but thanks to politics (and SLS) its likely going to have have to be either business, academia or another country. Politics makes all things complicated. But if an ally (like Australia) came forward, esp. if they not only came with a checkbook but with a request for contract to have SpaceX build an Australian launch complex with them.... But let's see what Bridenstein can pull off. Same goes for Starlink. That needs to be developed, built, and launched quickly in quantity for them to maintain the number of satellites that goes with their FCC agreement. That's a "use it or lose it" type of thing. You can't apply for and be granted bandwidth and just "sit on it". You have to use it. Improving Falcon 9 and Falcon Heavy reuse will help keep costs down for launching Starlink as well. All good. |
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Space X 2nd stage recovery
JF Mezei wrote on Tue, 24 Apr 2018
16:36:20 -0400: On 2018-04-24 14:21, David Spain wrote: I am of the opinion that the existing F9 and F9H architectures will be (crew-wise) underutilized. Unless the space station life is extended beyond 2025, FH and Dragon2 may very well remain the workhorse for mnanned space in USA. So Boeing is irrelevant in your mind? And unless there is real funding for manned space programme beyond ISS, nobody will see much business case to invest in manned space programme from now on, unless you go for it on your own (aka: SpaceX with BFR to Mars). The issue here is that Bigelow seems to have jumped in bed with ULA. If that extends to ferrying supplies and 'guests' to 'space hotels', they might not let SpaceX vehicles dock. Where the "international" thing may fall in place is if SpaceX gets serius about mars and other countries want "in" on the project, supplying modules for the Mars colony or any other "help" they can provide to SpaceX. Or just people who want to go to Mars. If there are enough, it would make sense to launch from almost anywhere. But unless a place like Australia could provide a huge cost and logistics benefit to have SpaceX launch/land there, SpaceX might not be so interested when you consider transportation logistics for modules built in USA. Remember, BFR Spaceship can do point to point travel on Earth and land anywhere there's a big enough piece of concrete. In the case of a LEO assembly/refueling spot to later go to Mars, would launching from 12°S (northern Australia) offer significant performance advantage over 28°N (Canaveral)? I don't think it buys you that much. BFR Spaceship is 'no assembly required'. You just need to be able to launch fuel tankers to the same orbital plane. They're going to be doing the manufacturing in the LA area and then transporting to the original launch site by ship. I think all the inspection and such will occur at the launch site. That makes locating the facility outside the US something of an ITAR issue. I wouldn't expect Australia to be a problem, but you never know... -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw |
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Space X 2nd stage recovery
"JF Mezei" wrote in message ...
On 2018-04-24 07:10, Jeff Findley wrote: I'm glad they're working on upper stage recovery. My guess is that BFR/BFS will take a bit longer than Elon's aspirational schedule products. If SpaceX truly stops production of Merlin engine as it moves its operatiosn to BFR/BFS, despite recovering stage 1s, won't they eventually run out of engines for stage 2? I suspect they'll keep building engines for awhile, simply to have enough and to build in improvements. But the rate will probably decrease. or will SpaceX in reality continue to produce the engines at least for the upper stage config ? If they can recover stage 2 engines reliably, this could enable ending production of the engines to retool for BFR/BFS ? Eh, I'm not sure it's a huge problem. -- |
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Space X 2nd stage recovery
"JF Mezei" wrote in message ...
On 2018-04-24 07:10, Jeff Findley wrote: They do, to pressurize the kerosene and LOX tanks for the Merlin engine. Adding another gas would complicate pad operations (only a bit, but still). Wouldn't that require running additional piping up the launch tower and new connection points on the rocket to load the gas into the tanks, along with the pipe unhooking hardware at launch time? No you just use the existing piping and connection points. Is that considered "major" or a no brainer type of work? I think adding a few additional tanks is the least of the issues. Ensuring proper inflation and then controlling the lift enough to navigate is going to take the most work. But again, it's sort of a no-brainer. For the flights that can take the hit to the payload, you enable this option. You test until it works and then make it operational. If you fail, you haven't lost anything you haven't already written off. |
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Space X 2nd stage recovery
"Jeff Findley" wrote in message
... In article , says... "Jeff Findley" wrote in message ... I heard helium, because while lift isn't important, mass most certainly is. And at the same volume and pressure, helium masses less than nitrogen. The mass of the molecule doesn't enter into the ideal gas law: P*V = N*R*T Jeff Fair point. And I believe they already have helium tanks on board, just use those as part of the supply. They do, to pressurize the kerosene and LOX tanks for the Merlin engine. Adding another gas would complicate pad operations (only a bit, but still). Yeah, only a 'bit' but still some. And SpaceX seems to be focused more on the mantra of "simpler is better". They'd rather give up a hair of payload in return for simplifying operations. And this is a welcome contrast to performance uber alles. I'm glad they're working on upper stage recovery. My guess is that BFR/BFS will take a bit longer than Elon's aspirational schedule products. Agreed 100%. I never really believe his schedules until about 10 seconds to lift-off :-) As such, Falcon 9 and Falcon Heavy will remain the workhorses of SpaceX for many years to come. Anything they can do to cut their costs increases the cash they can funnel into BFR/BFS development. Perhaps. On the other hand they're spending more money developing this. Same goes for Starlink. That needs to be developed, built, and launched quickly in quantity for them to maintain the number of satellites that goes with their FCC agreement. That's a "use it or lose it" type of thing. You can't apply for and be granted bandwidth and just "sit on it". You have to use it. Improving Falcon 9 and Falcon Heavy reuse will help keep costs down for launching Starlink as well. Fair enough point. Jeff -- * I promise I will format my posts properly in the future. * Windows Live Mail just can't quote! Luckily, I have found this: * http://www.dusko-lolic.from.hr/wlmquote/ |
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