Author Topic: SpaceX Falcon Heavy Discussion (Thread 4)  (Read 713207 times)

Offline Robotbeat

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #320 on: 02/05/2016 12:38 am »
NASA
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Offline AncientU

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #321 on: 02/05/2016 02:09 am »
Not sure what you mean? 
The current 5.2m fairing is approximately 200m3.
Even filled with liquid methane only, it would mass 85tonnes; with Lox, 228tonnes.

.. and filled with steel it'd be 1600 tons. i.e., if you were building steel structures in space, using FH to launch the raw materials would give you 7.5 m3 of material per launch. That giant fairing would be mostly empty, suggesting you'd be wise to form it into less dense beams and girders or whatever.

I was responding to:
I guess people are thinking that if you have a large tonnage size, things like fuel for depots, structures for habitats, and such could be built or loaded in LEO for deep space travel or large space stations.  Then you are limited by volume.

Wasn't sure what spacenut was saying... if you are hauling dense payloads (fuel, steel, water...), then the FH would be mass limited, not limited by volume.  Still confused (but used to it).
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Offline Robotbeat

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #322 on: 02/05/2016 02:21 am »
They can always make a bigger fairing, just like the similarly-sized (in diameter) Atlas V has a 7.2m fairing as an option (that no one has ever ordered). But almost none of our spacecraft infrastructure is built for more than 5m diameter payloads, and shipping such enormous payloads is an enormous pain since you pretty much can't even use an airplane (limited to about 7m, and even then it's like a single aircraft that you'd have to rely on, at least in the US).

I think the whole "volume-limited" thing is overdone. 5m is fine, and you DON'T need a bigger launch vehicle to use a bigger-than-5m fairing.

Also, where the heck would you TEST such a huge fairing? As it is, 5m fairings barely fit at Plum Brook, which has the largest vacuum chamber in the world.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline sdsds

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #323 on: 02/05/2016 02:27 am »
Once the first FH vehicle has lifted from the pad we'll likely know a bit more about the cost (to SpaceX) of launching FH. Only then will we know, for easily divisible payloads like propellant or water, whether a single FH launch is more cost effective than multiple F9FT launches. I think Shotwell knows her potential customers well, and if she doesn't have any asking for 60 tons right now, she is prudent to defer public comment about that capability and how it might be priced.
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Offline sewebster

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #324 on: 02/05/2016 03:07 am »
Also, where the heck would you TEST such a huge fairing? As it is, 5m fairings barely fit at Plum Brook, which has the largest vacuum chamber in the world.

Isn't the vacuum chamber 100' in diameter and taller than that? The acoustic facility is smaller...

Offline Lars-J

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #325 on: 02/05/2016 06:26 am »
Dream on. :) They've never released that kind of performance detail for anything, what makes you think try will now?

So I guess you're saying you don't expect them to just release the source code for their calculations?  :(
Look I would be happy with the ISP and important mass elements for the new cores and upper stage as well as ISP and thrust data for the FT engines as long as they either describe the throttling profile of the centre stage and give at least performance of all expendable, centre core expendable side core RTLS, centre core ASDS side core RTLS and all RTLS.

Do you want them to release a cure for cancer while they are at it?...  ::) No one in the business releases that level of detail.

Offline nadreck

Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #326 on: 02/05/2016 01:39 pm »
Dream on. :) They've never released that kind of performance detail for anything, what makes you think try will now?

So I guess you're saying you don't expect them to just release the source code for their calculations?  :(
Look I would be happy with the ISP and important mass elements for the new cores and upper stage as well as ISP and thrust data for the FT engines as long as they either describe the throttling profile of the centre stage and give at least performance of all expendable, centre core expendable side core RTLS, centre core ASDS side core RTLS and all RTLS.

Do you want them to release a cure for cancer while they are at it?...  ::) No one in the business releases that level of detail.

No, I think the chance of them curing cancer is a little lower than the chance of them putting the ULA numbers up on a NASA website mentioned above.

Seriously were were promised updated FHFT numbers, I want enough to model as accurately as I can.
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline StuffOfInterest

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #327 on: 02/05/2016 02:29 pm »
One thing to keep in mind with all this discussion of larger payload fairings is road transport.  I doubt anything over the current size is going to be able to fit on the road in halves.  Will quarter slices get you back to small enough?  That adds more complexity.  Of course, there has been no mention of any actual payloads out there requiring larger than what is available now so much of this discussion is just burning pixels for fun.

Online matthewkantar

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #328 on: 02/05/2016 02:38 pm »
You could ship it in quarters but have it split in half at sep the same way the smaller fairings do. The flange and fasteners would make it a little heavier, but you could road ship some really big fairings in quarters without having to reinvent the sep event.

Matthew

Offline McDew

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #329 on: 02/05/2016 02:44 pm »
Yes, and the URL was NASA.gov. Thought that'd be sufficient for individuals capable of independent thought.

The best numbers we ever got for 1.1 came from there, came from NASA. I hope it is updated with full thrust and Falcon Heavy numbers.
The NASA site reflects the vehicle configurations and contractual performance offered by the contractors for the NLS-II IDIQ contract.  Contractors can only propose new offerings once a year during the on-ramp period (nominally each August).  Don't expect the numbers or configurations on the NASA site to change until after the next on-ramp/evaluation period.

Offline nadreck

Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #330 on: 02/05/2016 02:46 pm »
Yes, and the URL was NASA.gov. Thought that'd be sufficient.

The best numbers we ever got for 1.1 came from there, came from NASA. I hope it is updated with full thrust and Falcon Heavy numbers.

I got the numbers from spaceflight 101, the SpaceX web site and wikipedia - can you give me a more specific link on that site at NASA because I couldn't find data from there, just a web form for calculating performance (which is aspx and if I go view source I don't see the numbers it makes its calculations from)
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline Robotbeat

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #331 on: 02/05/2016 03:00 pm »
Yes, and the URL was NASA.gov. Thought that'd be sufficient.

The best numbers we ever got for 1.1 came from there, came from NASA. I hope it is updated with full thrust and Falcon Heavy numbers.

I got the numbers from spaceflight 101, the SpaceX web site and wikipedia - can you give me a more specific link on that site at NASA because I couldn't find data from there, just a web form for calculating performance (which is aspx and if I go view source I don't see the numbers it makes its calculations from)
Yes, you must actually calculate performance to a reference orbit of your choosing. That's better than Wikipedia (obviously), SpaceX (doesn't provide full orbit parameters and reserves some undefined amount of performance for reuse, according to Shotwell), and spaceflight101 (which isn't a primary source).

And because it gives you performance numbers to many different orbits, you can use it to calibrate your model much better than just giving a couple reference orbits (especially when it's "GTO" without specifying 1500 or 1800m/s-to-go)
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline Robotbeat

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #332 on: 02/05/2016 03:21 pm »
Yes, and the URL was NASA.gov. Thought that'd be sufficient for individuals capable of independent thought.

The best numbers we ever got for 1.1 came from there, came from NASA. I hope it is updated with full thrust and Falcon Heavy numbers.
The NASA site reflects the vehicle configurations and contractual performance offered by the contractors for the NLS-II IDIQ contract.  Contractors can only propose new offerings once a year during the on-ramp period (nominally each August).  Don't expect the numbers or configurations on the NASA site to change until after the next on-ramp/evaluation period.
That's a good point, however:

V1.1 was added before it was even flown. Full thrust has already flown. TESS, a NASA payload awarded under NLS (I believe) will necessarily fly on a Full Thrust because v1.1 is retired. This implies that Full Thrust is available through NLS somehow.

...so I think it odd that it hasn't already been updated publicly.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline nadreck

Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #333 on: 02/05/2016 03:28 pm »
Yes, you must actually calculate performance to a reference orbit of your choosing. That's better than Wikipedia (obviously), SpaceX (doesn't provide full orbit parameters and reserves some undefined amount of performance for reuse, according to Shotwell), and spaceflight101 (which isn't a primary source).

And because it gives you performance numbers to many different orbits, you can use it to calibrate your model much better than just giving a couple reference orbits (especially when it's "GTO" without specifying 1500 or 1800m/s-to-go)

But it does not give me the information I need to calculate anything. How can I use the calculation on this page to check my model of calculations if I don't know the masses they are assuming? Is the reference model in their calculations one with legs?

Back when the first TMI numbers went up on the SpaceX website I could use that with the data on SII engine performance and SII masses (wikipedia, spaceflight 101 and also the SpaceX website) to backwards calculate the speed the FH lofted the 2nd stage to in fully expendable mode. That gave me one point of sanity check for my model of FH operation.  This doesn't really give me any without knowing the numbers they used.
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline anonymousgerbil

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #334 on: 02/05/2016 03:31 pm »
I found something in the newest F9 user's guide (dated Oct 21st 2015) that perplexed me a bit, especially in regards to Falcon heavy:

Quote
SpaceX uses one of two PAFs on the launch vehicle, based on payload mass. The light PAF can accommodate payloads weighing up to 3,453 kg (7,612 lb), while the heavy PAF can accommodate up to 10,886 kg (24,000 lb).

Would this imply that for payloads greater than 10,886 kg a new PAF would be required?  Seems odd that they can't even max out the single stick with these 2 PAFs, let alone the FH LEO numbers.

Offline Robotbeat

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #335 on: 02/05/2016 03:35 pm »
I found something in the newest F9 user's guide (dated Oct 21st 2015) that perplexed me a bit, especially in regards to Falcon heavy:

Quote
SpaceX uses one of two PAFs on the launch vehicle, based on payload mass. The light PAF can accommodate payloads weighing up to 3,453 kg (7,612 lb), while the heavy PAF can accommodate up to 10,886 kg (24,000 lb).

Would this imply that for payloads greater than 10,886 kg a new PAF would be required?  Seems odd that they can't even max out the single stick with these 2 PAFs, let alone the FH LEO numbers.
The only thing heavier than 10t is Dragon for Falcon 9. Everything else is much lighter. Not many heavy payloads need to launch to LEO.

This is the Falcon 9 user's guide, not the Heavy's.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Offline anonymousgerbil

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #336 on: 02/05/2016 03:37 pm »
I found something in the newest F9 user's guide (dated Oct 21st 2015) that perplexed me a bit, especially in regards to Falcon heavy:

Quote
SpaceX uses one of two PAFs on the launch vehicle, based on payload mass. The light PAF can accommodate payloads weighing up to 3,453 kg (7,612 lb), while the heavy PAF can accommodate up to 10,886 kg (24,000 lb).

Would this imply that for payloads greater than 10,886 kg a new PAF would be required?  Seems odd that they can't even max out the single stick with these 2 PAFs, let alone the FH LEO numbers.
The only thing heavier than 10t is Dragon for Falcon 9. Everything else is much lighter. Not many heavy payloads need to launch to LEO.

This is the Falcon 9 user's guide, not the Heavy's.

The new user's guide covers both F9 and FH:  http://www.spacex.com/sites/spacex/files/falcon_9_users_guide_rev_2.0.pdf

Edit:  it at least somewhat talks about FH, doesn't seem to be comprehensive though.
« Last Edit: 02/05/2016 03:40 pm by anonymousgerbil »

Online oldAtlas_Eguy

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #337 on: 02/05/2016 04:52 pm »
Yes, you must actually calculate performance to a reference orbit of your choosing. That's better than Wikipedia (obviously), SpaceX (doesn't provide full orbit parameters and reserves some undefined amount of performance for reuse, according to Shotwell), and spaceflight101 (which isn't a primary source).

And because it gives you performance numbers to many different orbits, you can use it to calibrate your model much better than just giving a couple reference orbits (especially when it's "GTO" without specifying 1500 or 1800m/s-to-go)

But it does not give me the information I need to calculate anything. How can I use the calculation on this page to check my model of calculations if I don't know the masses they are assuming? Is the reference model in their calculations one with legs?

Back when the first TMI numbers went up on the SpaceX website I could use that with the data on SII engine performance and SII masses (wikipedia, spaceflight 101 and also the SpaceX website) to backwards calculate the speed the FH lofted the 2nd stage to in fully expendable mode. That gave me one point of sanity check for my model of FH operation.  This doesn't really give me any without knowing the numbers they used.
The values given by the orbit query is based on no margins (including no legs). No margins means no engine out either. The 1350 LEO and GTO values for v1.1 given by SpaceX included engine out margins + maybe a little more as well as attached legs and other recovery hardware margins. The two values gives the percentages or delta V/energy values for the stage deltas for no margins vs ASDS recovery for the v1.1. Now for FT we do not have any values.

Plus I do not think the numbers in the NASA query model will give you any answers since they are most likely a polynomial algorithm that given certain inputs returns an output. They may have no relationship to masses of stages or engine thrusts ISPs or anything else just a complex curve equation.
« Last Edit: 02/05/2016 04:58 pm by oldAtlas_Eguy »

Offline Lar

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #338 on: 02/05/2016 05:09 pm »
Removed some squabbling about where stuff was or will be posted. Please assume good faith, and remember, be excellent to each other.
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Offline Robotbeat

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Re: SpaceX Falcon Heavy Discussion (Thread 4)
« Reply #339 on: 02/05/2016 05:30 pm »
Yes, you must actually calculate performance to a reference orbit of your choosing. That's better than Wikipedia (obviously), SpaceX (doesn't provide full orbit parameters and reserves some undefined amount of performance for reuse, according to Shotwell), and spaceflight101 (which isn't a primary source).

And because it gives you performance numbers to many different orbits, you can use it to calibrate your model much better than just giving a couple reference orbits (especially when it's "GTO" without specifying 1500 or 1800m/s-to-go)

But it does not give me the information I need to calculate anything. How can I use the calculation on this page to check my model of calculations if I don't know the masses they are assuming? Is the reference model in their calculations one with legs?

Back when the first TMI numbers went up on the SpaceX website I could use that with the data on SII engine performance and SII masses (wikipedia, spaceflight 101 and also the SpaceX website) to backwards calculate the speed the FH lofted the 2nd stage to in fully expendable mode. That gave me one point of sanity check for my model of FH operation.  This doesn't really give me any without knowing the numbers they used.
The values given by the orbit query is based on no margins (including no legs). No margins means no engine out either. The 1350 LEO and GTO values for v1.1 given by SpaceX included engine out margins + maybe a little more as well as attached legs and other recovery hardware margins. The two values gives the percentages or delta V/energy values for the stage deltas for no margins vs ASDS recovery for the v1.1. Now for FT we do not have any values.

Plus I do not think the numbers in the NASA query model will give you any answers since they are most likely a polynomial algorithm that given certain inputs returns an output. They may have no relationship to masses of stages or engine thrusts ISPs or anything else just a complex curve equation.
Or sure, but you can use it to back out realistic values for all those things and to test your model. If you know lift-off mass, Isp, thrust, and payload to multiple orbits, you could actually back out dry masses, especially for a simple vehicle.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

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