Author Topic: SpaceX Falcon Heavy Discussion (Thread 5)  (Read 372641 times)

Online GWH

Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #600 on: 02/26/2017 05:10 pm »
Theoretically.  Needs either more propellant or much less mass for the delta v required.  See the dragon derived lunar lander thread in missions to the moon.

Offline Basto

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #601 on: 02/26/2017 05:25 pm »
A newbie here but I have been wanting to ask this so here goes. Could a F9H put a fueled Falcon second stage and Crew Dragon into lunar orbit? My math skills are not up to that, but I wonder if anyone here has worked that problem? My SWAG is that it could, but some of the second stage fuel would have to be used for a lunar orbit insertion retro burn.

Then could the Crew Dragon de-orbit, land propulsivley, and have enough left in the tank to re-orbit, dock to the second stage again (I know this is not designed at all) and use the S2 to boost home to Earth reentry. Basically an Apollo moon mission with decades newer technology.

SWAG: not quite. Just too much capability gap between Saturn V and F9H.

Anyone think so?

No, this won't work.  Dragon 2 doesnt have the DV to land, much less take off from the moon

Dragon 2 is designed to land on Earth, although certainly using the atmosphere to slow down helps with that, but didn't Musk say that Dragon 2 could land on any solid/liquid planet or moon in the solar system?

While you may be able to land it by filling it full of fuel it would be a one way trip.  Atmosphere makes a huge difference in the DeltaV required to land. Elon often makes these impractical off the cuff comments to pump up the capabilities of his hardware. (Like how the first stage of F9 having the required Dv to be an SSTO if it didn't have a payload)

D2 is just not designed for landing on a body without atmosphere.

Offline dglow

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #602 on: 02/26/2017 05:33 pm »
D2 is going to land on Mars, which doesn't have much atmosphere when compared to Earth.

Yes, Elon made a broad statement. A D2 could land on Luna if it carried enough propellant. Where that extra propellant might be stored, for a Mars landing, is an active topic in the Red Dragon thread.

Offline woods170

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #603 on: 02/26/2017 05:42 pm »
After 6 years of waiting, I'm just looking forward to seeing the hardware come together.

How about seeing what it would look like launching on a cloudy day?   :)


<snip images>


Yes, modified from the CRS-10 launch.

UPDATE:   Another photoshop pic related to FH eventually. I make no claims for a 2nd landing pad accuracy or location, it's for visualization.


<snip image>

Beautifull as these photoshops are would you kindly stop embedding images and attach them in stead? Thank you.
« Last Edit: 02/26/2017 05:43 pm by woods170 »

Offline meekGee

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #604 on: 02/26/2017 07:05 pm »
D2 is going to land on Mars, which doesn't have much atmosphere when compared to Earth.

Yes, Elon made a broad statement. A D2 could land on Luna if it carried enough propellant. Where that extra propellant might be stored, for a Mars landing, is an active topic in the Red Dragon thread.
Right, but the difference is high.

Dragon terminal velocity on Mars will be ~4 times higher than on earth, so say 800 m/s?  (Very roughly)

On the moon, it'll be the escape velocity, it 2400 m/s.

I didn't check to see if that dV will fit inside the Dragon body, but it's high enough that the sucky ISP begins to matter.

----

EDIT:  As DGlow points out below, we're in the wrong thread...

A quick BOE calc shows though that the propellant required to land on the moon easily exceeds Dragon's rated payload, whereas for atmospheric bodies (oh, say, just for example, Mars) the propellant is a fraction of the the rated payload.

In both cases, of course, the dry weight of Dragon can be reduced by getting rid of some subsystems, but even then landing on the moon is still a stretch, dV wise.

« Last Edit: 02/26/2017 08:34 pm by meekGee »
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Offline dglow

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #605 on: 02/26/2017 07:32 pm »
D2 is going to land on Mars, which doesn't have much atmosphere when compared to Earth.

Yes, Elon made a broad statement. A D2 could land on Luna if it carried enough propellant. Where that extra propellant might be stored, for a Mars landing, is an active topic in the Red Dragon thread.
Right, but the difference is high.

Dragon terminal velocity on Mars will be ~4 times higher than on earth, so say 800 m/s?  (Very roughly)

On the moon, it'll be the escape velocity, it 2400 m/s.

I didn't check to see if that dV will fit inside the Dragon body, but it's high enough that the sucky ISP begins to matter.

The point of my comment was to shift discussion to the proper thread.

Offline Kaputnik

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #606 on: 02/26/2017 08:28 pm »
A newbie here but I have been wanting to ask this so here goes. Could a F9H put a fueled Falcon second stage and Crew Dragon into lunar orbit? My math skills are not up to that, but I wonder if anyone here has worked that problem? My SWAG is that it could, but some of the second stage fuel would have to be used for a lunar orbit insertion retro burn.

Then could the Crew Dragon de-orbit, land propulsivley, and have enough left in the tank to re-orbit, dock to the second stage again (I know this is not designed at all) and use the S2 to boost home to Earth reentry. Basically an Apollo moon mission with decades newer technology.

SWAG: not quite. Just too much capability gap between Saturn V and F9H.

Anyone think so?

Falcon second stage mass is about 116t- so with a Dragon on top of that, over twice what a FH can lift to LEO.
So you would need two FH launches to do this, and you're still nowhere near lunar orbit.
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Online M.E.T.

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #607 on: 03/09/2017 05:42 am »
Just getting back to the Raptor upper stage for the Falcon Heavy. One of the main objections to this I have read on the forum is that it would require two different rocket engine assembly lines (one for the Merlin and one for the Raptor), thus significantly reducing SpaceX's cost efficiencies gained from economies of scale and so on.

So my question is, how do they plan to overcome this problem once ITS goes into production? Will this not require the production of both Raptors and Merlins in any case? After all, it's not as if they're going to be able to stop Falcon9 and Falcon Heavy production once ITS comes online. There will presumably always be a market for smaller rockets than the ITS.

So, since at that point they will be producing large numbers of Raptors for the ITS in any case, does it not make the idea of a Raptor upper stage for the Falcon rocket family a lot more feasible? And then, if you completely want to retire Merlin engine production, the conversion of all SpaceX rockets to Raptors thereafter?

But at the very least, if you're going to start producing 50-plus Raptors per ITS rocket in any case in a few years time, then the production lines are already there to make a few extra ones for use in your Falcon upper stage, whether for increased payload capabilities, or for the elusive goal of second stage reusability, which the Raptor might make possible.
« Last Edit: 03/09/2017 05:48 am by M.E.T. »

Offline macpacheco

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #608 on: 03/09/2017 09:15 am »
ITS stages cannot be built in Hawthorne, so a new production line will have to be setup.
Due to transport restriction on such massive stages, they will be build near the launch site (Musk stated that).
So no conflict between Falcon/FH and ITS assembly.
The actually assembly site haven't been announced yet though.
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Offline TomH

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #609 on: 03/09/2017 09:20 am »
Just getting back to the Raptor upper stage for the Falcon Heavy. One of the main objections to this I have read on the forum is that it would require two different rocket engine assembly lines (one for the Merlin and one for the Raptor), thus significantly reducing SpaceX's cost efficiencies gained from economies of scale and so on.

So my question is, how do they plan to overcome this problem once ITS goes into production? Will this not require the production of both Raptors and Merlins in any case? After all, it's not as if they're going to be able to stop Falcon9 and Falcon Heavy production once ITS comes online. There will presumably always be a market for smaller rockets than the ITS.

So, since at that point they will be producing large numbers of Raptors for the ITS in any case, does it not make the idea of a Raptor upper stage for the Falcon rocket family a lot more feasible? And then, if you completely want to retire Merlin engine production, the conversion of all SpaceX rockets to Raptors thereafter?

But at the very least, if you're going to start producing 50-plus Raptors per ITS rocket in any case in a few years time, then the production lines are already there to make a few extra ones for use in your Falcon upper stage, whether for increased payload capabilities, or for the elusive goal of second stage reusability, which the Raptor might make possible.

Raptor is for en entirely different purpose than Merlin. ITS will not replace F9. If anything, more Merlins will be produced as SX becomes more proficient and Block 5 becomes more reliable. Raptor should do nothing to affect economies of scale on the Merlin production line. Reusability of Merlins may balance out the increasing number of Falcon flights, though.

Online guckyfan

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #610 on: 03/09/2017 10:32 am »

Raptor is for en entirely different purpose than Merlin. ITS will not replace F9. If anything, more Merlins will be produced as SX becomes more proficient and Block 5 becomes more reliable. Raptor should do nothing to affect economies of scale on the Merlin production line. Reusability of Merlins may balance out the increasing number of Falcon flights, though.

I can not believe that. Once Raptor is in full production and reliable, they will want to terminate Merlin and Falcon production. Wether they do everything with ITS or build a smaller cousind, I don't know. I guess they will want something smaller and 7 engines like New Glenn look just about right. I just guess they want to do that after ITS flies, not before.

Offline su27k

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #611 on: 03/09/2017 11:57 am »
Just getting back to the Raptor upper stage for the Falcon Heavy. One of the main objections to this I have read on the forum is that it would require two different rocket engine assembly lines (one for the Merlin and one for the Raptor), thus significantly reducing SpaceX's cost efficiencies gained from economies of scale and so on.

I don't remember two engine production lines were ever raised as an objection, maybe you meant two upper stage production lines? The current upper stage seems to share a lot of tools with first stage, if you want a new 5m upper stage for Raptor, it would be a new production line thus expensive.

Offline Jim

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #612 on: 03/09/2017 12:31 pm »

I can not believe that. Once Raptor is in full production and reliable, they will want to terminate Merlin and Falcon production.

No, they won't.  It is still a source of income.  ITS is not going to produce income for awhile

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #613 on: 03/09/2017 12:37 pm »
Just getting back to the Raptor upper stage for the Falcon Heavy. One of the main objections to this I have read on the forum is that it would require two different rocket engine assembly lines (one for the Merlin and one for the Raptor), thus significantly reducing SpaceX's cost efficiencies gained from economies of scale and so on.

I don't remember two engine production lines were ever raised as an objection, maybe you meant two upper stage production lines? The current upper stage seems to share a lot of tools with first stage, if you want a new 5m upper stage for Raptor, it would be a new production line thus expensive.

Ah. I might have confused the two issues, if so.

However, didn't Elon say a while ago that they abandoned upper stage recoverability (for now) because it proved impossible with the Merlin engine? If a Raptor upper stage made full reusability possible, (in addition to allowing New Glenn level payloads on the expendable Falcon Heavy), would that not go some way to justifying the costs of the revised upper stage production line?


Offline spacenut

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #614 on: 03/09/2017 12:49 pm »
Ok, are they producing the Raptor with Merlin tools?  Are the combustion chambers the same size, larger, with a larger nozzle?  What about turbopumps.  The same or different/new pumps. 

If it is a completely different engine, seems like the Raptor will have it's own tooling and assembly line.  Merlin will still be needed for F9/FH for satellite launches and a steady stream of money. 

Therefore, why not develop the Raptor vacuum for use in a 5.2m upper stage?  This alone would greatly increase the FH' capabilities by 10-15 tons to LEO, and for cislunar activity which it seems is the direction NASA is wanting to go.  This would also make it a huge lower cost competitor for SLS and New Glenn. 

Offline Jim

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #615 on: 03/09/2017 12:58 pm »

However, didn't Elon say a while ago that they abandoned upper stage recoverability (for now) because it proved impossible with the Merlin engine? If a Raptor upper stage made full reusability possible, (in addition to allowing New Glenn level payloads on the expendable Falcon Heavy), would that not go some way to justifying the costs of the revised upper stage production line?



It has nothing to do with the engine. 
Just stop, Spacex has said no Raptor with Falcon

Offline rpapo

Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #616 on: 03/09/2017 01:03 pm »
Just stop, Spacex has said no Raptor with Falcon
As has been noted before: Raptor requires liquid methane as fuel.  The proper mass ratio of methane to oxygen is different from kerosene to oxygen.  The density of liquid methane is different.  The volume of tankage required to hold that mass of methane is very different.  You would most likely have to put the methane tank above the oxygen tank, which is the reverse of what happens now.  Essentially, you need a new rocket design.  And new infrastructure.  In many ways, you need to start over.
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Offline meekGee

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #617 on: 03/09/2017 02:34 pm »

Raptor is for en entirely different purpose than Merlin. ITS will not replace F9. If anything, more Merlins will be produced as SX becomes more proficient and Block 5 becomes more reliable. Raptor should do nothing to affect economies of scale on the Merlin production line. Reusability of Merlins may balance out the increasing number of Falcon flights, though.

I can not believe that. Once Raptor is in full production and reliable, they will want to terminate Merlin and Falcon production. Wether they do everything with ITS or build a smaller cousind, I don't know. I guess they will want something smaller and 7 engines like New Glenn look just about right. I just guess they want to do that after ITS flies, not before.
I think so too, but I am having difficulty picturing the market once ITS exists.  It'll be such a game changer.

It'll be a world with daily launches, manned and unmanned.

I'm pretty sure F9 will have no place there.
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Offline Jim

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #618 on: 03/09/2017 02:44 pm »

It'll be a world with daily launches, manned and unmanned.


Not in this or the next decade.

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Re: SpaceX Falcon Heavy Discussion (Thread 5)
« Reply #619 on: 03/09/2017 02:49 pm »

It'll be a world with daily launches, manned and unmanned.


Not in this or the next decade.

I think that is pretty much accepted. With ITS likely to only land the first humans on Mars from 2026 onward (on an optimistic timeframe), the era of hundreds of ITS flights per launch cycle to Mars is not likely to arrive until well into the 2030's or 2040's. I don't think even Elon is claiming anything different.

So the era of daily launches is pretty much a dream for the 2030's, at the earliest.

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