Author Topic: SpaceX Falcon Heavy Discussion (Thread 2)  (Read 189930 times)

Offline newpylong

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #20 on: 08/09/2014 11:01 PM »
I think FH is on track. The F9v1.1 had to work first and that's been less than a year.

Additionally I suspect they were waiting to get 39A under there control and built first.

It's a different vehicle than the F9. Just because it looks like 3 F9's squished together doesn't mean it's as easy as building 3 F9's.

These things take time.  Re-using the boosters, even if it's just the outside 2 may depend more on an FAA permission to land  and landing pads than the ability to do so. I'd be surprised if they wait for that.  They have certification for the Feds and paying customers that want to see it work before they hand over the dough.

I see barge landings as a demonstration not direct reuse.  That's going to be a tricky feat to get it down and back to port.  Maybe not impossible but certianly a few very interesting pieces of equipment and procedures and people in very close proximity to an active rocket.  Which is usually not recommended.

SpaceX, when the FH launches, regardless of re-useability is going to make the cost and schedule of SLS (built from existing parts) look horrid.

I want the FH to succeed wildly and be fully reusable.  Maybe we'll know in a years time.

 ::)
This is not on topic but SLS does not use "existing parts" save for 4 flights of RS-25.

Offline GregA

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #21 on: 08/11/2014 02:42 AM »
If they are providing a quality product and are efficient enough to beat the competitors there is no reason, in fact it would be fiscally irresponsible to go as cheap as possible.  SpaceX needs cash flow and profit like all companies, they've spent hundreds of millions on development and they have huge plans.  That will never be funded with sub 10 million dollar launches. 

If a competitor improves and gets cheaper than lower your price but not until you have too.

Yes they have to fund their Mars projects :) The combination of showing they CAN do cheap spaceflight plus they can make a healthy profit will interest some. Still it's no wonder Musk doesn't want to float SpaceX until all the pieces are well and truly in place!

On another note, SpaceX might be in the interesting position of setting their price as 30% cheaper (or whatever) than any competitor. If the competitor tries to match their price they know SpaceX will reduce another 30% because they can and have said they will, so the competitor will not reduce until they know their own costs are sustainable.

In any case, customers are going to pay more for "first use" rockets (for now, as the competitors will spin that as being less risk), and pay more for expendable ("last use") rockets for their extra launch mass. The "regular use" launches will be the cheapest.
« Last Edit: 08/11/2014 02:44 AM by GregA »

Offline GregA

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #22 on: 08/11/2014 02:43 AM »
SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time.
Is it official that the first FH won't have cross feeding?

Offline Llian Rhydderch

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #23 on: 08/11/2014 04:08 AM »

In any case, customers are going to pay more for "first use" rockets (for now, as the competitors will spin that as being less risk), and pay more for expendable ("last use") rockets for their extra launch mass. The "regular use" launches will be the cheapest.

I don't know that this is the way its going to work out...

...but I like your theory; and I think you've advanced the discussion here by advancing it.

The mid-term market for space launch does look like it might birfurcate (trifurcate?) into the sort of product offering distinctions you've articulated here.  And if the terms catch on, we will all know GregA @ NSF said it first:  the "first use"/"last use"/ "regular use" pricing model of space launch in the late 2010s.   ;D
Re arguments from authority on NSF:  "no one is exempt from error, and errors of authority are usually the worst kind.  Taking your word for things without question is no different than a bracket design not being tested because the designer was an old hand."
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Online douglas100

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #24 on: 08/11/2014 10:28 AM »
SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time....

Surely if the core throttles down it will burn longer than the boosters?

Quote
Now, first they have to convince Range that flying three 50m towers at the same time is perfectly safe and there's no chance of collisions.

Agree with that. It would be a sight to behold.
Douglas Clark

Offline cambrianera

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #25 on: 08/11/2014 11:55 AM »
The discussion on Jon Goff's MAC on Reusable Second Stage Configuration thread http://forum.nasaspaceflight.com/index.php?topic=32180.msg1232404#msg1232404 made me think that such a system could also be applied to center stage of heavy.
Eliminating 2000-3000 m/s of DV from the core before starting the boostback burn could be an advantage in term of payload.
The MAC system should be lighter than the propellant needed for the braking part of the burn (about 20-25 ton).
Oh to be young again. . .

Offline guckyfan

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #26 on: 08/11/2014 12:16 PM »
The discussion on Jon Goff's MAC on Reusable Second Stage Configuration thread http://forum.nasaspaceflight.com/index.php?topic=32180.msg1232404#msg1232404 made me think that such a system could also be applied to center stage of heavy.
Eliminating 2000-3000 m/s of DV from the core before starting the boostback burn could be an advantage in term of payload.
The MAC system should be lighter than the propellant needed for the braking part of the burn (about 20-25 ton).

I don't know how useful it would be for boostback. It will travel forward during deceleration. But it should help a lot for downrange recovery. It could reduce the payload penalty for the core to the MAC, the landing legs and landing fuel, which would be quite small.

Offline baldusi

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #27 on: 08/11/2014 12:57 PM »

SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time....

Surely if the core throttles down it will burn longer than the boosters?

But the FH boosters have more propellant than the core, their tanks reach about above the interstage. I've calculated a 10% extra propellant. When I did the numbers for typical MaxQ and throttling at 70%, hey burned about the same time. Elon might have said that 60% was possible, which might give the core more time, though.

Offline MP99

Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #28 on: 08/11/2014 01:43 PM »

SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time....

Surely if the core throttles down it will burn longer than the boosters?

But the FH boosters have more propellant than the core, their tanks reach about above the interstage. I've calculated a 10% extra propellant. When I did the numbers for typical MaxQ and throttling at 70%, hey burned about the same time. Elon might have said that 60% was possible, which might give the core more time, though.

FH carries a bigger payload than F9 - call it (53-13)/2 = 20t per booster (eventually). The core & u/s may also have some additional dry mass over F9 to cope with the greater payload.

9x M1D on F9 core also lifts interstage, 200klb u/s prop, u/s burnout mass, payload adapter, up to 13t of payload, and PLF.

Other than the 20t+ for extra payload & dry mass, all of that extra mass needs to be replaced by prop to keep liftoff T:W the same.

ISTM 80t+ per booster, which is more like 20%?



But, there is also an argument that there must be some prop remaining at booster MECO (BECO?), at least when operating in expendable mode.

F9 has to throttle to keep G-levels OK (call it 5G - doesn't matter if that's a bit out).

If all 27 engines remain burning until some combined MECO event, I don't see how G-levels could stay anywhere near 5G.

Of course, if you're recovering the boosters, then they will BECO with some prop mass remaining, which would help keep the G levels in check. So, this is more an argument for how it couldn't work (27 engine cut-out) in expendable mode.

cheers, Martin

Online douglas100

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #29 on: 08/11/2014 03:50 PM »

SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time....

Surely if the core throttles down it will burn longer than the boosters?

But the FH boosters have more propellant than the core, their tanks reach about above the interstage...

Oops! Forgot that! You're correct.
Douglas Clark

Offline Elmar Moelzer

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #30 on: 08/11/2014 05:25 PM »
But isn't the interstage where the cold gas thrusters and some of the other equipment (avionics, etc) are located? If they fill the entire interstage with tanks, where do these things go?
« Last Edit: 08/11/2014 05:25 PM by Elmar Moelzer »

Offline corrodedNut

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #31 on: 08/11/2014 07:00 PM »
But isn't the interstage where the cold gas thrusters and some of the other equipment (avionics, etc) are located? If they fill the entire interstage with tanks, where do these things go?
The boosters will have nosecones that serve the same purpose.

Offline Lobo

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #32 on: 08/11/2014 10:57 PM »
SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time. Thus, it should not be un expected that all three cores might be recovered.
Now, first they have to convince Range that flying three 50m towers at the same time is perfectly safe and there's no chance of collisions. So, unless they do a dance of F9R-Dev1/2/3 in NM, it will be a tough ssale.

I'd expect an attempted RTLS recovery of the outboard boosters if they've already successfully demonstrated that with F9R.  And then either an expended central core, or a water landing somewhere downrange to test the effects of reentry from that altitude and speed on it.

I think going from RTLS one core to 3 might be a big jump all at once.  Try two, and then on the next flight try all three.  Meanwhile they have telemetry on what the central core does which will be useful for them later if they want to try to recover the central core downrange somehow.


Offline wannamoonbase

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #33 on: 08/12/2014 06:07 PM »
I have a question for our community.

If the FH is going to fly from KSC in 2015, when do you think we will see it on a test stand in McGregor and what would you expect the testing there to be?

I think probably 6 months before scheduled launch
Tests starting with simple static fire for a few seconds gradually building to longer burns that include the core throttling down and simulated separation of the side boosters. 

A full duration burn would be reasonable but can they support a full FH burn on the stand with regards to their permits and deluge system?

Edit: Spelling
« Last Edit: 08/12/2014 06:10 PM by wannamoonbase »
Excited to be finally into the first Falcon Heavy flow, we are getting so close!

Offline CraigLieb

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #34 on: 08/12/2014 06:32 PM »
I have a question for our community.

If the FH is going to fly from KSC in 2015, when do you think we will see it on a test stand in McGregor and what would you expect the testing there to be?
...

Adjunct questions:
  - Has anyone outside of SpX seen FH Stage 1 cores in production? 
  - Would two of the S1 cores be identifiable as FH due to their increased length?
« Last Edit: 08/12/2014 06:33 PM by CraigLieb »
Colonize Mars!

Offline Moe Grills

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #35 on: 08/14/2014 07:16 PM »
Is there a likely orbit that they will use for the first Heavy launch to demonstrate its capability? Similarly are they likely to give it a payload, or simply show that it behaves as expected?

How about a parabolic/extreme elliptical orbit that would take a mockup or a 'boilerplate' version of the Dragon on a cislunar flyby? Of course it is not going to happen; Elon Musk does not like carrying out stunts for stunt's sake. And besides, does Elon care what anybody says here on this forum?

Offline Karloss12

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #36 on: 08/14/2014 08:15 PM »
Does anyone want to bet that the FH initial flight will be delayed until the cores can be recovered?

Or would that delay be to long?

Or will there be no need for a delay as cores will recovered by early 2015?

Offline AJW

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #37 on: 08/14/2014 09:54 PM »
I believe that the first priority was to prove the ability to meet existing demand and clear some of the F9 backlog.  This has required both clearing technical launch hurdles and removals of bottlenecks in the production line.  Given a choice between clearing three paying commercial launches, or launching one FH test flight seems straight forward when the first paid FH launch isn't planned until late 2015 or even 2016.  Having recoverable cores dovetails nicely with the current timeline and I would think that if production is truly ramped up, if launch issues are resolved, if core recovery is proven in the next few launches, then at least two of the FH cores should be recoverable.  That is still a lot of "if's"

Offline Mader Levap

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #38 on: 08/15/2014 12:22 AM »
Does anyone want to bet that the FH initial flight will be delayed until the cores can be recovered?
I doubt that they would slip FH over it, if they could not reliably recover stages by then for some reason.

Or will there be no need for a delay as cores will recovered by early 2015?
If they are lucky (read: successful stage recovery relatively soon, first FH launch relatively late), indeed they could try to recover at least two out of three first stages of FH on first flight.
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Offline Robotbeat

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Re: SpaceX Falcon Heavy Discussion (Thread 2)
« Reply #39 on: 08/15/2014 01:54 AM »

SpaceX will quite probably try to recover at least the boosters. An important consideration, is that since it will lack any cross feeding, and assuming that the core throttles down after MaxQ, all three should deplete by about the same time....

Surely if the core throttles down it will burn longer than the boosters?

But the FH boosters have more propellant than the core, their tanks reach about above the interstage. I've calculated a 10% extra propellant. When I did the numbers for typical MaxQ and throttling at 70%, hey burned about the same time. Elon might have said that 60% was possible, which might give the core more time, though.

FH carries a bigger payload than F9 - call it (53-13)/2 = 20t per booster (eventually). The core & u/s may also have some additional dry mass over F9 to cope with the greater payload.

9x M1D on F9 core also lifts interstage, 200klb u/s prop, u/s burnout mass, payload adapter, up to 13t of payload, and PLF.

Other than the 20t+ for extra payload & dry mass, all of that extra mass needs to be replaced by prop to keep liftoff T:W the same.

ISTM 80t+ per booster, which is more like 20%?



But, there is also an argument that there must be some prop remaining at booster MECO (BECO?), at least when operating in expendable mode.

F9 has to throttle to keep G-levels OK (call it 5G - doesn't matter if that's a bit out).

If all 27 engines remain burning until some combined MECO event, I don't see how G-levels could stay anywhere near 5G.

Of course, if you're recovering the boosters, then they will BECO with some prop mass remaining, which would help keep the G levels in check. So, this is more an argument for how it couldn't work (27 engine cut-out) in expendable mode.

cheers, Martin
Youre calculating wrong. If you use the 52t figure for FH, Falcon 9 v1.1 should be given the 16t to LEO figure in the NLS II contract. Those two figures were released at the same time, so it seems likely to me they have the same assumptions behind them.
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