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docmordrid
2014-Feb-21, 04:26 AM
Yesterday SpaceX’s propulsion VP Tom Mueller said their upcoming Raptor methane staged combustion engine will deliver 1,000,000 lbf each and will be used in a cluster of 9 per core. This performance up from a previously announced 650,000 lbf.

He also mentioned a Mars payload of ~100 tonnes.

Raptor components are supposed to start testing at NASA Stennis this year.

http://www.pacbiztimes.com/2014/02/19/spacexs-propulsion-chief-elevates-crowd-in-santa-barbara/

Elukka
2014-Feb-21, 08:00 PM
They've said before that Raptor is an engine family rather than a single engine, so it might be a different engine altogether from the one that's going to be tested soon.

cjl
2014-Feb-21, 10:42 PM
1Mlbf and 9 per core? It's certainly possible, but I have my doubts that they would jump straight to that from their current ~160klbf per engine. That would give them more liftoff thrust (substantially) than a Saturn V.

ravens_cry
2014-Feb-22, 07:12 AM
1Mlbf and 9 per core? It's certainly possible, but I have my doubts that they would jump straight to that from their current ~160klbf per engine. That would give them more liftoff thrust (substantially) than a Saturn V.
That was pretty obvious given that it will be supposed to put 100 tonnes on Mars. We're getting into Nova territory here.

docmordrid
2014-Feb-22, 08:33 AM
Just imagine an FH style tri-core with 27M lbf. Not sure they'd go there unless they built a new heavily acoustic suppressed pad far from civilization, similar to the underground FH stand at McGregor but larger, or behind a big horseshoe berm.

publiusr
2014-Feb-23, 10:40 PM
N-1 didn't have the volumetric efficiency of Saturn V, but it is #1 in terms of thrust...11 million pounds work as per the wiki at least. Then Energiya. Saturn V is third, then shuttle.

So this is between N-1 and Energiya. I wonder what went with Beal's filament winding machines. That pressure-fed BA-1 first stage was to have more thrust than an SRB.

cjl
2014-Feb-24, 04:10 AM
That was pretty obvious given that it will be supposed to put 100 tonnes on Mars. We're getting into Nova territory here.

Sure, but at the same time, a 9Mlbf core isn't nearly large enough to put 100t on mars (unless you're talking about either a triple core FH-style vehicle, or in-orbit assembly after several launches). The Saturn V could only put about half of that to TLI, and it had a hydrolox upper stage (which is inherently quite a bit better at high-energy orbits such as escape trajectories than the methalox or kerolox designs SpaceX has so far).

publiusr
2014-Feb-25, 12:01 AM
Musk has no experience with LH2. That's why I support SLS, since it is already sized to house hydrogen in its ET based core block--so its upper stage will have similar needed volume.

Garrison
2014-Feb-25, 02:09 AM
Musk has no experience with LH2. That's why I support SLS, since it is already sized to house hydrogen in its ET based core block--so its upper stage will have similar needed volume.

Well luckily Musk isn't designing the engine personally so that isn't an issue. Unlike certain senators he lets professionals do the design work.

cjl
2014-Feb-25, 02:16 AM
Musk has no experience with LH2. That's why I support SLS, since it is already sized to house hydrogen in its ET based core block--so its upper stage will have similar needed volume.

I fail to see the relevance, since right now, SpaceX isn't even planning to use LH2 for any of their vehicles. If they did, however, as Garrison points out, they can always hire professionals with the relevant experience.

ravens_cry
2014-Feb-25, 04:20 PM
Sure, but at the same time, a 9Mlbf core isn't nearly large enough to put 100t on mars (unless you're talking about either a triple core FH-style vehicle, or in-orbit assembly after several launches). The Saturn V could only put about half of that to TLI, and it had a hydrolox upper stage (which is inherently quite a bit better at high-energy orbits such as escape trajectories than the methalox or kerolox designs SpaceX has so far).
Given their past designs, that doesn't sound out of the realm of possibilities.

Garrison
2014-Feb-25, 11:40 PM
Given their past designs, that doesn't sound out of the realm of possibilities.

This page has an outline of SpaceX ideas. Couple of years old but I assume the Merlin 2 is what they are currently calling the Raptor:

http://nextbigfuture.com/2010/08/spacex-talks-falcon-x-heavy-for-125.html

ETA: Nope rereading I realize they are discussing the Raptor as a separate design.

docmordrid
2014-Feb-28, 02:56 PM
A separate design that could grow. Their history with Merlin is that they start with modest pressures and thrust (85 klbf) then grow to higher levels as they improve the design. Merlin 1D is now 147 klbf but Musk says that is only 85% of what it can do, which would be nearly 2x the initial design. If you apply that methodology to Raptor you get 2 mlbf.

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publiusr
2014-Feb-28, 10:10 PM
Unlike certain senators he lets professionals do the design work.

Actually, that's what the Senators are doing too. But folks in JPL have been chain-smoking Delta IIs to the point they became a crutch. They might have been handed out like Lucky Strikes, but they are not good for you.

A nice fat blunt full of LH2 and not kerosene is a lot healthier ;) Better shroud diameter for the Godzilla rover I linked too here on another post. The Delta II is not your friend, and SLS is not your enemy.

I do wish more details on MCT and BFR would come out all the same. He could stand to use that big vertical weld tool too.

Noclevername
2014-Feb-28, 10:53 PM
So, the article says that according to John Favreau, Musk inspired the character Tony Stark? Who has been around in comics since the 60s? That time-travelling idea thief!

Garrison
2014-Feb-28, 11:46 PM
Actually, that's what the Senators are doing too.

Oh come now, the Senate did everything bar pick the colour. Academic of course since it will be cancelled long before it gets near a launch pad.

ravens_cry
2014-Mar-01, 06:30 AM
If he can get the clout to get a NERVA style upper stage, more the power to him. Even with the tempereture limitations of a solid core nuclear rocket, their high ISP make them far better upper stage than even LH/LOX.

publiusr
2014-Mar-01, 06:32 PM
Oh come now, the Senate did everything bar pick the colour. Academic of course since it will be cancelled long before it gets near a launch pad.

Everything? I guess that means Harry Reid runs MSFC and the folks at Marshall pass legislation then. Last I heard, Marshall designs heavy lifters and the Senate listened to those experts and did what they wanted. It is a lot like Direct. I don't see it cancelled--and it will carry NERVA (one day.)

Getting back to Musk...I think MCT may be a methane burner...

His Falcon 9 Heavy will have about as many engines to keep up with as N-1 did.

Speaking of which, I saw a very interesting variation on the N-1 Musk might want to look at
http://www.astronautix.com/lvs/n1mok.htm
http://www.astronautix.com/stages/n1mok.htm

I think that lifting body is a good deal larger than Dream Chaser, the modified NK-33s were to use LH2, and if I'm not mistaken, that is an annular aerospike.
It isn't that different than Uragan.

Musk needs to work with Bezos, who prefers such a design, a bit closer to Bono's squat reusables.

A Musk N1 MOK with Skylon engines as a tail-sitter would be quite a sight to see. About the same number of engines as Falcon Heavy, only shorter and wider--that might make for a better tail-sitter.

Stratolaunch could always be made larger
http://www.buran.ru/htm/foto9.htm#tupolev_aks

Garrison
2014-Mar-01, 10:09 PM
I'm not going to derail any further on the SLS.


Musk needs to work with Bezos, who prefers such a design, a bit closer to Bono's squat reusables.

What exactly do you think Blue Origin can bring to the table? SpaceX has a working rocket design, they are getting closer to producing a reusable first stage (Blue Origin don't seem to have gotten beyond the Powerpoint presentation stage with this idea), SpaceX will hopefully test their Heavy version soon and they've repeatedly successfully launched and retrieved a vehicle from orbit; demonstrating key technologies required for DragonRider. I would love to see Blue Origin produce a working vehicle but they seem to be a long way from doing so.

BTW: Could you please stop posting as if Elon Musk were actually Tony Stark? It is the engineers at SpaceX that design and build the hardware it is not some one man band where Musk lovingly hand crafts every component himself.

NEOWatcher
2014-Mar-03, 01:23 PM
I (Blue Origin don't seem to have gotten beyond the Powerpoint presentation stage with this idea)...
And; they are only going for suborbital for a while it seems.

Elukka
2014-Mar-03, 02:26 PM
A Musk N1 MOK with Skylon engines as a tail-sitter would be quite a sight to see. About the same number of engines as Falcon Heavy, only shorter and wider--that might make for a better tail-sitter.
It would go rather counter to their successful design philosophy of achieving low prices and good reliability through keeping things simple. Musk's opinion when it comes to airbreathers specifically:

"With respect to air breathing hybrid stages, I have not seen how the physics of that makes sense. There may be some assumptions that I have that are incorrect, but really, for an orbital rocket, you're trying to get out of the atmosphere as soon as possible because the atmosphere is just as thick as soup when you're trying to go fast, and it's not helped by the fact that the atmosphere is mostly not oxygen. It's 80% nitrogen. So, mostly what you're air breathing is chaff, not wheat, and having a big intake is like having a giant brake. The braking effect tends to overwhelm the advantage of ingesting 20% oxidizer. You could just make the boost stage 5% to 10% larger and get rid of all the air breathing stuff and you're done."

docmordrid
2014-Mar-05, 03:18 PM
>
What exactly do you think Blue Origin can bring to the table?

The BE-3, a liquid hydrogen engine perfect for an evolved high Isp upper stage. Throttleable from 25 klbf to 110 klbf too.

Both F9 and FH could use it to increase their GTO and BEO payload capacities beyond what RP-1, or even methane, can deliver. For FH close to SLS Block 1.

BO gets orbital flight history, SpaceX a high Isp engine. Too bad it's unlikely to happen.

http://www.nasa.gov/content/blue-origin-test-fires-new-rocket-engine/#.Uxc_Xcso7qA

docmordrid
2014-Mar-08, 01:32 AM
NASASpaceFlight.com has a major new story about Raptor, it's component tests, and some info the BFR's that'll us it. Another story about the launchers and MCT will follow.

What isn't the story (yet) is Level 2 forum data that makes it clear one of these launchers is a true monster. Scary big.

http://www.nasaspaceflight.com/2014/03/spacex-advances-drive-mars-rocket-raptor-power/

cjameshuff
2014-Mar-08, 01:44 PM
The BE-3, a liquid hydrogen engine perfect for an evolved high Isp upper stage. Throttleable from 25 klbf to 110 klbf too.

Except SpaceX isn't very interested in messing with hydrogen, and is interested in using stuff developed in-house to reduce production and operating costs.
(And throttling isn't very useful for an upper stage.)

publiusr
2014-Mar-08, 08:46 PM
Could you please stop posting as if Elon Musk were actually Tony Stark? It is the engineers at SpaceX that design and build the hardware it is not some one man band where Musk lovingly hand crafts every component himself.

Gladly--as long as you quit saying Senators are Chief Designers.


I'm not going to derail any further on the SLS.

Thank you.


The BE-3, a liquid hydrogen engine perfect for an evolved high Isp upper stage. Throttleable from 25 klbf to 110 klbf too. Too bad it's unlikely to happen.

They really do need to co-operate. I still wonder why Dream Chaser doesn't choose Falcon Heavy--they could scale up their Lifting Body to HL-42 size.


Except SpaceX isn't very interested in messing with hydrogen, and is interested in using stuff developed in-house to reduce production and operating costs.
(And throttling isn't very useful for an upper stage.)

If you are going to use hydrogen--and go to Mars, it makes sense to have the container be as large as possible, since LH2 is low density high volume.

This gives you big payload shrouds.

All NTR craft I have seen require some type of shuttle-derived HLLV.

Garrison
2014-Mar-09, 01:24 AM
They really do need to co-operate. I still wonder why Dream Chaser doesn't choose Falcon Heavy--they could scale up their Lifting Body to HL-42 size.

No they really don't; while I'm sure SpaceX would be happy to sell Sierra Nevada a launcher scaling up would the last thing they want to do with Dream Chaser. It was going down that route that wrecked the original vision of the space shuttle. Keep the crew vehicle and the cargo carriers separate; cheaper and simpler in the long run.

publiusr
2014-Mar-09, 07:58 PM
This "keeping crew and cargo separate" religion is just that. I rather like the Liberty "trunk" design after all.
http://www.nasaspaceflight.com/2014/02/nasa-iss-resupply-options-through-2024/

Besides, a somewhat scaled up Dream Chaser is hardly a shuttle--it just allows some food stuffs and bulkier items to accompany astronauts--HL-42 would have been cheaper than STS and was a low risk design: It had a small cargo hold that wasn't to be sneezed at

http://www.astronautix.com/craft/hl42.htm

It was to be about 28 metric tons, well within Falcon Heavies' envelope, the extra payload eaten up by the recovery of the cores, so it looks to mesh well. It would still be considered a mini-spaceplane..just not as cramped.

Garrison
2014-Mar-09, 11:20 PM
This "keeping crew and cargo separate" religion is just that. I rather like the Liberty "trunk" design after all.


And despite my attempt to put things back on a polite basis you resort to jibes within two posts; classy. I think I'm done responding to you.

docmordrid
2014-Mar-10, 10:50 AM
Not to mention his has wandered pretty far from Raptor and the proposed SHLV's.

Back on point....

With a thrust close to Saturn V the single core could probably fly from Pad 39A or Boca Chica, but that tri-core with >20 million lbf is beyond pad 39A's design limits. Boca Chica is probably too close to Brownsville and South Padre Island's resorts for the tri-cores acoustics as well.

ISTM the fix is to either build a new pad at KSC, perhaps 39C, or to build a pad along the Gulf coastline (or perhaps a bit inland) between Boca Chica and Corpus Christi. Not much there but gophers.

publiusr
2014-Mar-10, 08:31 PM
Homestead AFB was hit pretty hard by Andrew...I wonder if there are sections of that that Space X could use. Even farther south than Canaveral, but probably too close to a lot of homes.

I think your 39 C concept might be the only option. The crawlers are already there...and SLS funds to uprate them are already in place, so that gives him an asset he doesn't have to pay for.

docmordrid
2014-Mar-13, 04:26 AM
The big question about the crawlers is if their plume openings are large enough. The tri-core is going to be >30 meters wide.

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Elukka
2014-Mar-13, 08:42 AM
SpaceX so far has integrated and moved their rockets horizontally, Russian-style.

Van Rijn
2014-Mar-13, 08:59 AM
NASASpaceFlight.com has a major new story about Raptor, it's component tests, and some info the BFR's that'll us it. Another story about the launchers and MCT will follow.

What isn't the story (yet) is Level 2 forum data that makes it clear one of these launchers is a true monster. Scary big.

http://www.nasaspaceflight.com/2014/03/spacex-advances-drive-mars-rocket-raptor-power/

Wow. They are moving further into new territory with that engine and the large rockets. This is where I could see them more likely to hit a snag.

On the other hand, aside from his talk about Mars colonization, I could see where this could be what really sells reuse. (The article makes clear they're intending the bigger rockets to be reusable). Since the fraction to orbit is smaller with reuse, a bigger rocket is better. Also, this engine should be lower maintenance and the fuel is cheaper.

Long before we'd have a Mars colony, there would be space hotels. Imagine being a passenger in one of those things (and a real passenger section - dozens of people). They'd probably have Super-duper dracos for the emergency system on the passenger module.

II wonder if motion sickness medicine would be a standard issue for passengers? It wouldn't be much fun if half the people are getting sick.

NEOWatcher
2014-Mar-13, 01:01 PM
The big question about the crawlers is if their plume openings are large enough. The tri-core is going to be >30 meters wide.
That's not a function of the crawler, it's a function of the mobile launch platform that sits on top of the crawler.
The current MLPs are being sold for scrap. They were able to reconfigure them from Apollo to shuttle.
I would assume that the MLPs wouldn't be that big of a deal to either build or modify (at least in relation to the crawler).

publiusr
2014-Mar-13, 06:13 PM
Flight plume modeling has been done recently with SLS:
http://forum.nasaspaceflight.com/index.php?topic=31740.msg1168373#msg1168373

That at least has a nice deluge system--and only has to go up.

If reusability is the goal, how will Space X deal with exhaust on the landing pad?

I wonder if it would be wise to use grating system atop, say (I know this sounds crazy) something looking like the big vertical sinkholes we've seen on the web. Is BFR to land as well--and are all three standard cores on Falcon Heavy to have legs? The art shows the central core with legs too.

Elukka
2014-Mar-13, 07:57 PM
It doesn't seem to be a problem. They've already landed Grasshopper a lot of times and it's very similar to a 'real' landing since both involve burning a single Merlin 1D.

publiusr
2014-Mar-15, 07:03 PM
Since it isn't an air-breather, I guess they don't have to worry as much about kicking up rocks, although the thrust might be a little hard on asphault. Still good to keep everything debris free...

docmordrid
2014-Mar-22, 08:57 PM
If F9R is any indicator the landing pad will only have to deal with the plume of the center Raptor, and likely not at full throttle.

This comparison pic really shows how big the "BFR" single core will be....

http://img.tapatalk.com/d/14/03/23/u5aru8e2.jpg

Now imagine the triple-core.....

ravens_cry
2014-Mar-23, 12:48 AM
Whoa! That is indeed a Big <expletive redacted/> Rocket!

Garrison
2014-Mar-23, 10:10 PM
If F9R is any indicator the landing pad will only have to deal with the plume of the center Raptor, and likely not at full throttle.

This comparison pic really shows how big the "BFR" single core will be....

Now imagine the triple-core.....BFR of course stands for 'Big Falcon Rocket'. ;)

docmordrid
2014-Mar-23, 10:36 PM
On the kiddie boards yes, but we know what it really means ;)

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Noclevername
2014-Mar-23, 11:14 PM
Brobdingnagian Flaming Rustbucket.

Bright Flying Raptors.

Blasting Fiery Rider.

publiusr
2014-Mar-30, 08:09 PM
I guess the only really good art has to be on L2 at nasaspaceflight.com, but those aren't official?

docmordrid
2014-Apr-22, 03:23 AM
Raptor engine component tests begin in about 1 month.

http://mseigs.com/nasa-spacex-cut-ribbon-to-launch-testing-partnership/


NASA, SpaceX Cut Ribbon To Launch Testing Partnership

An April 21 ribbon-cutting ceremony at NASA’s Stennis Space Center near Bay St. Louis, Miss., marked the beginning of a new NASA and Space Exploration Technologies Corp. (SpaceX) partnership aimed at continuing to propel America’s burgeoning commercial space program forward and enhance utilization of NASA’s advanced test facilities. Several Mississippi leaders joined NASA and SpaceX representatives for the ceremony including Gov. Phil Bryant, U.S. Sen. Thad Cochran and U.S. Rep. Steven Palazzo.
*
SpaceX signed a Space Act Agreement with the space agency last fall to test components of its methane-fueled Raptor rocket engine on the E-2 Test Stand at Stennis. SpaceX is developing the Raptor as a reusable engine for a heavy-lift launch vehicle.
*
“This is a great partnership between NASA and SpaceX,” Stennis Center Director Rick Gilbrech said. “These types of activities are opening new doors of commercial space exploration for companies. SpaceX is another example of the outstanding progress America’s commercial space industry is making, and we are happy to welcome them as our newest commercial test customer.”
*
Since the fall, Stennis has performed necessary maintenance to prepare the test stand and completed equipment modifications needed to accommodate Raptor components.
*
With preparations complete, the ribbon-cutting ceremony paves the way for testing which is scheduled to begin within a month.
*
“SpaceX is proud to bring the Raptor testing program to NASA’s Stennis Space Center and the great state of Mississippi,” said Gwynne Shotwell, President and COO of SpaceX. "In partnership with NASA, SpaceX has helped create one of the most advanced engine testing facilities in the world, and we look forward to putting the stand to good use.”
*
The Mississippi Development Authority and the Hancock County Port and Harbor Commission played key roles in the endeavor by fostering and supporting the new partnership.


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publiusr
2014-Apr-26, 07:44 PM
Great news Dr. Mordrid!

Shotwell said something that made me really happy recently: http://nextbigfuture.com/2014/04/spacex-provides-more-information-on.html

"From a commercial perspective Falcon Heavy, it's an over-sized vehicle. Its got more capacity than folks in this room need - unless we wanna put two of the biggest satellites on this vehicle and fly them both to GTO. That would yield a pretty respectable price for folks. But what we are really trying to do is, push the bounds of technology with respect to size of launch vehicles"

THAT is the point, to get folks to dump this thinking that all humanity needs is a Titan IV/Delta IV class rocket and no more. I want to see a push for public and private HLV research both. I think the increase in LV size is something that should be pursued for its own sake.

docmordrid
2014-Apr-29, 07:21 AM
As do I, and Musk recently said they have a 15 million lbf thrust vehicle in mind.

IMO that sounds like a Block 2 of the original BFR single core this first Raptor is for.

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docmordrid
2014-Apr-30, 01:01 AM
HOLD THE PHONE....

At 10:00 AM on Saturday May 17 Jeff Thornburg, Spacex's Principal Propulsion Engineer will make a presentation about Raptor at ISDC 2014 (International Space Development Conference), which takes place between may 14-18

"Raptor High Performance Rocket Engine"

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NEOWatcher
2014-Apr-30, 12:00 PM
HOLD THE PHONE....
Call me back. I'm going to forget by then. ;)

Luckchong
2014-May-10, 04:02 PM
It would be possible to mount a manned mission to Mars today with existing technology. Two space shuttles should be refitted with modern GaAs computers, faster, lower weight, and most importantly, do not need external cooling. GaAs is similar to CMOS, but better. Each shuttle can carry 30,000 lb to low earth orbit. Using turbo/ramjet engines instead of the ammonium perchlorate, powdered aluminum boosters, which compress air into a tank as they rise (fuel weight is lost, air weight is added) and add the air back once the craft gets above 70,000 ft and going more than mach 3, would allow half of the liquid hydrogen/ liquid oxygen fuel tank to survive into low earth orbit. Launching two such crafts in rapid succession would allow them to join in orbit, and have one complete liquid hydrogen/ liquid oxygen tank between them. This composite of two identical shuttles and one full hydrogen/oxygen tank would be enough to place the craft into a highly elliptical orbit having the Lagrange points of Mars within the orbit, thus allowing the craft to fall into orbit around Mars. The craft has 60,000 lb of payload with enough life support for four astronauts for seven months, and a tiny two-person landing craft. Once the mission is accomplished and the craft is again falling toward the Earth's Lagrange points, the extra weight is released. The reason for two identical crafts is redundancy in case of a failure mid-flight.

docmordrid
2014-May-10, 09:48 PM
The Shuttle is not suited for interplanetary flight; it's far too.heavy and would burn up re-entering either at either Earth or Mars from transit velocities. Even if it landed on Mats, how would you come home? No pad 39A, no external tanks and no SRB boosters, not to mention no vehicle assembly building or mobile launch pad.

Rockets and spacecraft are not Legos.

ravens_cry
2014-May-11, 07:09 AM
Not to mention that, even if they could take the heat, I really doubt the wings would be big enough for a safe landing in the thin atmosphere.

cjameshuff
2014-May-11, 12:17 PM
A "tiny two-person landing craft" is mentioned for Mars. But that "tiny" craft is another large chunk of mass you have to haul along.



It would be possible to mount a manned mission to Mars today with existing technology. Two space shuttles should be refitted with modern GaAs computers, faster, lower weight, and most importantly, do not need external cooling. GaAs is similar to CMOS, but better.

GaAs needs more cooling than silicon due to the lack of an equivalent to CMOS (it lacks the native oxide layer used for the dielectrics in silicon CMOS, and the hole mobility needed for high speed P-channel transistors needed for complementary logic), requiring use of logic implementations with higher power consumption. None of which actually matters, silicon electronics aren't what's holding the Shuttle back from use as an interplanetary craft.



Each shuttle can carry 30,000 lb to low earth orbit. Using turbo/ramjet engines instead of the ammonium perchlorate, powdered aluminum boosters, which compress air into a tank as they rise (fuel weight is lost, air weight is added) and add the air back once the craft gets above 70,000 ft and going more than mach 3, would allow half of the liquid hydrogen/ liquid oxygen fuel tank to survive into low earth orbit.

Jet engines are heavy and have low thrust to weight ratios, high pressure compressed air tanks are heavy, as is the air being compressed into them, compressed air is a lousy rocket oxidizer, there's the heating of the compressed air, the inlet drag, the limited time spent in the atmosphere, etc...this just doesn't work. It isn't even "existing technology".



Launching two such crafts in rapid succession would allow them to join in orbit, and have one complete liquid hydrogen/ liquid oxygen tank between them. This composite of two identical shuttles and one full hydrogen/oxygen tank would be enough to place the craft into a highly elliptical orbit having the Lagrange points of Mars within the orbit, thus allowing the craft to fall into orbit around Mars. The craft has 60,000 lb of payload with enough life support for four astronauts for seven months, and a tiny two-person landing craft. Once the mission is accomplished and the craft is again falling toward the Earth's Lagrange points, the extra weight is released. The reason for two identical crafts is redundancy in case of a failure mid-flight.

You haven't demonstrated that you actually have the delta-v for departing Earth and entering Mars orbit, and then returning. You're hauling an enormous amount of dead weight in the two Shuttles. On top of this, your engines are not designed to be reignited in orbit, and the external tank can't store liquid hydrogen for long periods. The Shuttle had extremely limited maneuvering capability, intended to allow a Shuttle carrying a much smaller burden to rendezvous in LEO and then dip back into the upper atmosphere for return. The Shuttles are also meant to operate in the LEO thermal and radiation environment for no more than a few weeks at a time, and as docmordrid mentioned, would not survive reentry from an interplanetary trajectory.

Finally, what does this have to do with the Raptor engine?

docmordrid
2014-May-11, 05:07 PM
Nothing, and our Raptor IQ will be expanded greatly in a few days (May 17.)

The kremlinology of SpaceX statements indicate there have been 3 iterations of Raptor,

660,000 lbf: planning, announced in 2013

1 million lbf: leaked by Tom Mueller (VP of Propulsion) early this year. Likely after detailed Sims were run.

1.67 million lbf: from Musk, who stated a 9 engine core would have 15 million lbf of thrust (15/9 = 1.67) a few weeks ago.

The discussions at NSF and elsewhere center around the idea of a 1 million lbf block 1 engine and a 1.67 million lbf block 2, the latter being used in a stretched core - like the F9 1.0 to F9 v1.1 transition,

Apparently with a full-flow staged combustion engine tweaking the preburners can boost the pump outputs enough to get the extra thrust without enlarging the rest of the engine, which can explain this designs rapid growth during development.

We may find out more next Saturday, or not.

Swift
2014-May-13, 12:31 PM
Finally, what does this have to do with the Raptor engine?
Nothing, as far as I can tell.

Luckchong, welcome to CQ. If you want to discuss your idea further, please start your own thread about it.

docmordrid
2014-Jul-08, 07:09 PM
OK, the updated Raptor performance numbers given at the May Joint Propulsion Conference in Cologne, Germany have come out from the black.

They were behind an Aviation Week paywall but ULA posted them to their Daily Clipsheet blog, then they were posted to aerospace forums by readers..

Checked with a mod before posting.

Point of reference is the Saturn V's Rocketdyne F-1 engine.

t = metric tonnes.
lbf = lb/ft
Isp = efficiency, stated in seconds. Higher is better. 250 is OK, 300 is good, close to or over 400 is great. Propellant and engine design specific. 2-5 Isp points ARE significant.

Rocketdyne F-1 (Saturn V)

Propellants: RP-1 (kerosene)/LOX

Sea level thrust: 680.58t (1,500,000 lbf)
Vacuum thrust: not used in upper stage
Isp: 260 seconds

SpaceX Raptor (#'s may still be low)

Propellants: methane/LOX

Sea level thrust: 705t (1,554,259 lbf)
Vacuum thrust: 840t (1,851,883 lbf)
Isp: 380 seconds

9 Raptor engines in the first stage.

cjl
2014-Jul-09, 12:02 AM
I'm guessing that 380s specific impulse is vacuum, while the 260s for the F1 is sea level? 260 sounds awfully low (even for a gas generator hydrocarbon engine) for vacuum, and 380 sounds awfully high for a non-hydrogen engine (even staged combustion) at sea level.

docmordrid
2014-Jul-09, 02:53 AM
F-1/260 is SL, and Raptor/380 is Vac. Raptors SL Isp is probably around 320-330. Remember this is a full-flow staged combustion, not a "regular" one. Raptor would be the first of this type to fly.

Think of the engine types as the Russians do, how the props arrive at the injectors: a gas generator is liquid-liquid, a staged combustion is gas-liquid and a full flow is gas-gas.

The only full gas-gas engine that fired I can find was the unsuccessful Russian RD-270 engine (1960's.) It had a SL ISP of 301 and a Vac of 322 using hypergolics. The US's integrated Power head Demonstrator (2000's) never got to completion or flight.

Nicolas
2014-Jul-09, 08:12 AM
9 engines, each more powerful than the F1 of which Sat5 had 5, that sounds like a lot of ooomph to get things going. And the regular Falcon Heavy (27 Merlins) already is (will be) a beast.

NEOWatcher
2014-Jul-09, 11:52 AM
F-1/260 is SL, and Raptor/380 is Vac. Raptors SL Isp is probably around 320-330.
According to Astronatica (http://www.astronautix.com/engines/f1.htm) F1 vacuum is 304. So; Your range sounds right to me.
Side note: F1 isp was increased after A9. So if you want to say "moon rocket", an isp of 265 would be the better choice.

docmordrid
2014-Jul-09, 12:26 PM
The Rocketdyne Archives says SA-504 and after was 263, which splits the difference. Still, it's a far cry from Raptor territory.

And yes, the BFR (placeholder name) will be a monster. Some of the guys at NSF are estimating a disposable lift to LEO of about 300 tonnes. The reusable mode payload would still be enormous.

Also, Falcon Heavy #1 is on the production floor at Hawthorne now. The FH test facility at McGregor is also said to be nearing completion.

http://img.tapatalk.com/d/14/07/09/u6e4ader.jpg

Months old FH stand image. Newer images on NSF show a lot of work has been completed, but IIRC they're copywrited by the pilot who took them in June.
http://img.tapatalk.com/d/14/07/09/e6epeqa7.jpg

Nicolas
2014-Jul-09, 01:39 PM
Does any of the Raptor engine exist outside of computer simulation already at this moment in time?

docmordrid
2014-Jul-09, 04:32 PM
Raptor is no PowerPoint.

Starting last year NASA & SpaceX began the upgrading of the E2 test stand at NASA Stennis (Mississippi) for methane/LOX propellants. They cut the ribbon in April. Stennis is NASA's main engine development facility.

SpaceX started testing injector elements in May, with more components to follow. SpaceX engine developments tend to be fast once they go public. That train left the station late last year.

Because of the Dragon V2's SuperDraco abort/landing engines being 3D printed there has been speculation that parts of Raptor will be as well. This could speed the development cycle.

NASA very much wants SpaceX to test the full Raptor engine and first stage at Stennis as well, and that districts congressman chairs the House space sub-committee. One of Mississippi's 2 US Senators is the #2 seniority Republican in the Senate. Do the math.

cjl
2014-Jul-10, 08:10 PM
The Rocketdyne Archives says SA-504 and after was 263, which splits the difference. Still, it's a far cry from Raptor territory.


Well, of course. One is a full flow, staged combustion, high pressure methane design, and the other is a gas-generator hydrocarbon engine with a relatively low chamber pressure. Each was designed with different objectives in mind (and for first stage use, you could make a case that the hydrocarbon engine is a great choice, due to its relatively small size (for the thrust level) and simplicity, and because rocket performance isn't terribly sensitive to first stage isp.

cjameshuff
2014-Jul-10, 09:38 PM
Well, of course. One is a full flow, staged combustion, high pressure methane design, and the other is a gas-generator hydrocarbon engine with a relatively low chamber pressure. Each was designed with different objectives in mind (and for first stage use, you could make a case that the hydrocarbon engine is a great choice, due to its relatively small size (for the thrust level) and simplicity, and because rocket performance isn't terribly sensitive to first stage isp.

Technically methane's every bit as much a hydrocarbon as RP-1...I never did think "hydrocarbon" was a smart choice of terminology.

CH4 actually only has a moderate specific impulse advantage over RP-1, and they're very close to even after the density tradeoff is taken into account. However, RP-1 is a very narrowly defined blend of hydrocarbons, not just standard kerosene, and coking is still an issue with it. It might be much easier to build a reusable full-flow staged combustion engine using methane, and that gives a quite substantial increase in specific impulse.

On top of making it easier to build a high-performance engine, the logistics and economics of fueling your rockets with methane are potentially much nicer. Nearly pure methane is already widely piped around, and separating methane from the other components of natural gas is a quite simple process. It's even conceivable to use the other constituents and some of the methane to power the process on-site...natural gas goes in, liquid methane comes out.

IsaacKuo
2014-Jul-11, 01:54 PM
Given the potential advantages of methane, why don't we already have any production methane engines? Surely there are some problems or technology risk issues involved.

In particular, Elon Musk's ultimate target was always Mars colonization, and must have surely been thinking of methane-lox as the ultimate goal from the start. And yet, he chose to begin with kerolox engine development...

Why?

I'm sure there are reasons, but I don't know what--and that's why I'm asking.

galacsi
2014-Jul-11, 06:30 PM
Given the potential advantages of methane, why don't we already have any production methane engines? Surely there are some problems or technology risk issues involved.

In particular, Elon Musk's ultimate target was always Mars colonization, and must have surely been thinking of methane-lox as the ultimate goal from the start. And yet, he chose to begin with kerolox engine development...

Why?

I'm sure there are reasons, but I don't know what--and that's why I'm asking.

Maybe an other advantage of methane is that the two gases (O2 & CH4) has to be kept at about the same low temperature. It is a simplification compared with LOX and kerosen.

But you are right , one can ask why this has not been done before ?

docmordrid
2014-Jul-11, 06:43 PM
Russia tried a FFSC decades ago (RD-270) but it used hypergolics. The US had the hydrolox Integrated Powerhead Demonstrator but it never was finished. SpaceX just picked up the ball and ran with it.

Interesting point: one of the guys at NSF ran the numbers on Raptor and discovered the only chamber pressure that fit was only about 34% higher than Merlin 1D's. This indicates that even with its current huge thrust numbers it could go MUCH higher in a Block 2.

ravens_cry
2014-Jul-11, 06:46 PM
If I may make a guess, the reason methane was chosen is four little letters, ISRU.
There's quite a few places in the solar system where Methane either exists naturally or the component chemicals are easy to get a hold of.

cjl
2014-Jul-11, 07:58 PM
Given the potential advantages of methane, why don't we already have any production methane engines?

If specific impulse isn't really a huge factor, RP-1 is still easier to store (non-cryogenic), more dense, and better understood due to historical engine designs. Sure, methane gives better specific impulse (around 10 seconds or so in an equivalent engine design, if I remember right), but historically, if specific impulse is important, designers have bypassed methane and gone straight for LH2/LOX designs instead (since they give a ~90 second improvement in ISP rather than just 10).

IsaacKuo
2014-Jul-11, 10:03 PM
If specific impulse isn't really a huge factor, RP-1 is still easier to store (non-cryogenic), more dense, and better understood due to historical engine designs.
Thanks!

The impression I get is that here in the US there really hasn't been much historical success or tribal knowledge in kerolox engine design (not to the extent of Soviet designs).

But I could see density being what sealed the decision for Elon Musk. The diameter of Falcon was restricted by considerations of what could be most easily transported by highway. Given that relatively narrow diameter, fuel density would have a big impact on the length of the rocket. Excessive length would affect road transport considerations as well as difficulty of erecting the rocket from horizontal to vertical.

cjameshuff
2014-Jul-11, 10:33 PM
Kerosene was the conservative, low-risk choice. There's been several projects that used methane, and I don't recall ever hearing about them as being particularly problematic or troublesome, but it's not been used before outside of small experiments. SpaceX's goal was reduction in cost, and RP-1 went right along with the gas generator cycle as being a well-established technology, unlikely to contain hidden costs in development or operation.

Now they're trying something more ambitious and difficult, a staged combustion engine that gives much higher performance. The known costs of using kerosene are more important there (coking being more difficult to manage), and methane offers an opportunity to avoid them without taking on the other costs of using hydrogen, and has some other appealing characteristics in its similarity to LOX in density and temperature. Ability to easily do ISRU is an advantage in the very long run, but the switch to methane makes sense for this engine anyway.

As for why nobody else has used methane...why bother? There's been no incentive to reduce costs or improve technology, or to risk any change at all. ULA's been launching Atlas Vs and Delta IVs in essentially unchanged form for about as long as SpaceX has existed. It's hardly been an example of a thriving, highly competitive industry...there's been a few established players in comfortable ruts and the occasional expensive supertech project that's of little realistic threat to them.