SpaceX Merlin 1C Engine

[Giovanni DS]

Would be possible to cluster 4 merlins and create something like the rd170 ? this could cut the costs probably.

[meiza]

RD-170 has one gas generator and pump, just four chambers and nozzles. Interesting proposal nevertheless. If the nozzle and thrust chamber manufacturing infrastructure is complex, with all the grooved copper and the nozzle tubings, it could make sense.

I think it was done for the RD-170 because a single F-1 size thrust chamber was troublesome with thrust oscillations. Merlin 2 is probably still a very long way from that scale, Merlin 1 is 1/17th.

Here's a table of a few lox/kerosene engines. Thrust is sealevel/vacuum.

Merlin - Falcon 1 & 9 - 450/500 kN
RS-27C - Delta II - 900/1000 kN
RD-180 - Atlas V - 3800/4200 kN
F-1 - Saturn V - 6700/7700 kN
RD-171 - Zenit 2/3sl - 7600/7900 kN

A good easy to remember rule of thumb is that F-1 was 7 MN (meganewtons).
RD-171 is roughly similar. So RD-180 is about half of that. You need about nine Merlin 1:s to match the RD-180.

[hop]

A good easy to remember rule of thumb is that F-1 was 7 MN (meganewtons).
RD-171 is roughly similar. So RD-180 is about half of that. You need about nine Merlin 1:s to match the RD-180.

And they won't match the ISP, and so probably aren't a viable drop-in replace anyway.

Adding ISPs (vac/sl) from astronautix.com

Merlin - Falcon 1 & 9 - 450/500 kN - 304/??? (from spacex, probably for the non-C version), 310/261 (from astronautix, probably old ?)
RS-27C - Delta II - 900/1000 kN - 302/255
RD-180 - Atlas V - 3800/4200 kN - 338/311
F-1 - Saturn V - 6700/7700 kN  - 304/265
RD-171 - Zenit 2/3sl - 7600/7900 - 337/309
A couple more possibly relevant entries
RD-117 - Soyuz-FG strap-on - 800/1000 - 310/264 (there seems to be some conflict between sources about the exact specs, and which variant goes with which launcher)
NK-33 - N1/K1/"Taurus II" - 1510/1638 - 331/297

[coach]

"Clearly they're smart enough to know rocket engines don't scale linearly, since Merlin isn't just a linear scale-up of Kestrel, and it looks like they have the talent to do it. The question is, do they have a reason to do it? And do they have the money to do it? Those are both market-based questions, at whose answer I couldn't hazard a guess."

William, I'll hazard a guess.  Robert Bigelow will have thriving R&D/tourism market in LEO soon.  SpaceX is a likely transport.  Soon after (2020?), Bigelow will start putting inflatables on the moon.  SpaceX will be the transport.  Because of the low cost and steady income of private enterprise, SpaceX and Bigelow will build a Mars rocket and inflatable habitat (2030?).  NASA may even pay for the initial trips.  NASA may get to the moon first but Musk and Bigelow will set up shop.

Just a guess.


Coach

[jimvela]

coach - 14/11/2007  7:51 PM
NASA may get to the moon first but Musk and Bigelow will set up shop. Just a guess.

At the current slow rate of exploration progress, the first NASA astronaut on Mars might take the Virgin Galactic/SpaceX/Northrop mars express, check in at the Bigelow Mars Uzboi Vallis, and drive off in an Eddie Bauer edition Hertz/GM Mars Hummer IX.  They could stop off at the BP/Mars for an homebrew fuelup, and rent a tour of the interesting places from the Six flags mars extreme adventure.  They could get the trip for half price if that rental had the big red Anheuser-Busch "Bud" logo plastered on the hood.

Even that would be great for SpaceX, there'd be a bundle of private rockets in such a mission.

Too bad we can't put our petty differences aside and mount a mission with modules and missions from all the space faring nations.  We could be there in a decade to stay.

[Comga]

meiza - 14/11/2007  6:05 PM
..... You need about nine Merlin 1:s to match the RD-180.

That's why it's a Falcon-9, don't you think?

coach - 14/11/2007  7:51 PM
William, I'll hazard a guess.  .....  Soon after (2020?), Bigelow will start putting inflatables on the moon.  

Not if NASA can help it, and they can.  Check out this:
http://www.spaceref.com/news/viewpr.html?pid=24027
Bigelow talks about putting his modules on the moon and POOF!  NASA has their first inflatable module in years ready for trials in Antarctica. (Anyone know any of the financial details of the Dover contract for inflatable structures? )

With or without the best of intentions, some parts of NASA will undercut the commercial market. The kind view is that these people seriously believe that their labor intensive, document heavy process is the only way to do space missions reliably.  Therefore they feel that they are doing the right thing by running programs that parallel private efforts, which they don't believe have sufficient quality and rigor to succeed.  The unkind view is that they are defending their turf.

Bigelow sees that NASA can duplicate their technology, which started with abandoned NASA technology, and provide "internal" competition for a product Bigelow wants to offer to NASA.  That has to put some damper on their business plans beyond LEO stations.  That puts some damper on the market for SpaceX to pursue moon capable rockets, if such a thing were to exist.

coach - 14/11/2007  7:51 PM

SpaceX and Bigelow will build a Mars rocket and inflatable habitat (2030?). NASA may even pay for the initial trips. [/QUOTE]

Not if the pattern continues.  NASA *IS* the customer for Moon and Mars flights.  They are signaling, intentionally or not, that they don't want to buy missions or mission hardware.  Their jobs are and have been to make mission hardware and run missions.  Anything industry can develop, the can pay people to replicate, only with "appropriate" processes and quality control.

We can only hope that Musk and Bigelow can generate a sufficient independent market for private space stations, and build the seriously complicated systems to get people to orbit and support them their.  If they can make a go of that, and it is by no means assured, they may be able to branch out on their own.  But first (and second and third)... things first.

[wannamoonbase]

Comga - 14/11/2007  11:45 PM
SpaceX and Bigelow will build a Mars rocket and inflatable habitat (2030?). NASA may even pay for the initial trips.

I'll take that bet.  

Space exploration is not like computers or the internet it does not evolve into a new generation every 18 months.

I wasted much of my 20's waiting for SSTO and second generation RLVs, then I learned enough to know that the status quo is that way for many good reasons.  Its hard accelerating something to 5 or 7 miles per second and getting it there safely.  

SpaceX is going to learn a great deal as they roll out the F9 and they will start to resemble ULA and other established operators.

Sadly, until flight rates go up significantly to make RLVs worth while or someone can make a Carbon fiber nanotube elevator and keep it operating we are looking for improvements in the single digit percentage points.

[William Barton]

meiza - 14/11/2007  8:05 PM

RD-170 has one gas generator and pump, just four chambers and nozzles. Interesting proposal nevertheless. If the nozzle and thrust chamber manufacturing infrastructure is complex, with all the grooved copper and the nozzle tubings, it could make sense.

I think it was done for the RD-170 because a single F-1 size thrust chamber was troublesome with thrust oscillations. Merlin 2 is probably still a very long way from that scale, Merlin 1 is 1/17th.

Here's a table of a few lox/kerosene engines. Thrust is sealevel/vacuum.

Merlin - Falcon 1 & 9 - 450/500 kN
RS-27C - Delta II - 900/1000 kN
RD-180 - Atlas V - 3800/4200 kN
F-1 - Saturn V - 6700/7700 kN
RD-171 - Zenit 2/3sl - 7600/7900 kN

A good easy to remember rule of thumb is that F-1 was 7 MN (meganewtons).
RD-171 is roughly similar. So RD-180 is about half of that. You need about nine Merlin 1:s to match the RD-180.

Probably why there's 9 Merlins on the bottom of a Falcon 9 and one RD-180 on the bottom of an Atlast V?  :laugh:

[William Barton]

coach - 14/11/2007  9:51 PM

"Clearly they're smart enough to know rocket engines don't scale linearly, since Merlin isn't just a linear scale-up of Kestrel, and it looks like they have the talent to do it. The question is, do they have a reason to do it? And do they have the money to do it? Those are both market-based questions, at whose answer I couldn't hazard a guess."

William, I'll hazard a guess.  Robert Bigelow will have thriving R&D/tourism market in LEO soon.  SpaceX is a likely transport.  Soon after (2020?), Bigelow will start putting inflatables on the moon.  SpaceX will be the transport.  Because of the low cost and steady income of private enterprise, SpaceX and Bigelow will build a Mars rocket and inflatable habitat (2030?).  NASA may even pay for the initial trips.  NASA may get to the moon first but Musk and Bigelow will set up shop.

Just a guess.


Coach

When I hazard guesses they're called science fiction stories. In my most recent publication, I had my astronauts make it to a NEO with a hodge-podge of Bigelow, SpaceHab, SpaceDev, and SpaceX hardware, bought with a $600M grant from the Gates Foundation. Fun to write and see in print, but, sadly, the real world seldom conforms to my wishful thinking.

[A_M_Swallow]

hop - 15/11/2007  2:00 AM

Adding ISPs (vac/sl) from astronautix.com

Merlin - Falcon 1 & 9 - 450/500 kN - 304/??? (from spacex, probably for the non-C version), 310/261 (from astronautix, probably old ?)

If the Merlin's ISP is smaller than estimated will the Falcons have to reduce their payloads?

[meiza]

Smaller than estimated by whom and when? Your question does not make any sense.

[A_M_Swallow]

meiza - 15/11/2007  7:17 PM

Smaller than estimated by whom and when? Your question does not make any sense.

I quoted 3 estimates of the ISP, your answer could choose which ever one is appropriate.  The payload sizes are stated on SpaceX's website.  All the values to complete the question are therefore available even if the answer is likely to be embarrassing.


Quoting from the SpaceX website on 15 November 2007

Page 19 of the Falcon 1 User Guide says
"Falcon 1 Launch Vehicles are capable of delivering approximately a 723 kg (1590 lbs) payload
into a due east (9.1 degree) low Earth orbit with 200 km circular altitude, when launched from
Omelek Island in the Kwajalein Atoll."

From the Falcon 9 webpage:
"Falcon 9 Performance
Launch Site:                                             Kwajalein         Cape Canaveral AFS
Inclination:                                                 9 degree      28.5 degree
LEO Mass to Orbit (185 km circular):     10,400 kg        9,900 kg
GTO Mass to Orbit (185 x 35,788 km):    5,070 kg      4,900 kg
"

[meiza]

There were two, one by astronautix (old) and one by spacex.
You can read Elon's old updates, I think there he mentions how close they were to reach efficiency, thrust and ISP figures when the original Merlin 1 was developed. I think they were pretty close but somewhat below. I don't remember what Falcon I figures were released when. Falcon 9 wasn't even planned back then.

It's been an ongoing development, both the engine and the rockets. It's not a simple question. Payload, margins and designs have probably fluctuated a lot.

[hop]

Given the astronautix number is so far off spacex own, I'd take it with a grain of salt. It could be from a very early estimate something like that. I only included it because I couldn't find any sea level value anywhere else, and thats where I got the other numbers.

[coach]

"With or without the best of intentions, some parts of NASA will undercut the commercial market."

Who will be able to live in these NASA inflatables?  Only NASA astronauts.  Who will do scientific research in them?  Only NASA employees.  Bigelow will build his inflatables "across the street" from NASA's and will use professional astronauts along with scientists from all backgrounds and tourists from anywhere in the world.  

A reduction in cost to the lunar surface by a factor of ten through innovation over the next two decades is not unreasonable.  This cost reduction may be low enough for corportations and universities, as well as rich private citizens, to do research and business on the moon.  NASA can't undercut this endeavor no more than they can undercut DirectTV from putting a satellite in orbit.


Coach

[Chris-A]

On a hunch, I was looking up a old flight global article and Merlin 1c 92k lb thrust is the block I design with the plump upgrade will increase the thrust to 102k lb, block II.

[coach]

"At the current slow rate of exploration progress, the first NASA astronaut on Mars might take the Virgin Galactic/SpaceX/Northrop mars express, check in at the Bigelow Mars Uzboi Vallis, and drive off in an Eddie Bauer edition Hertz/GM Mars Hummer IX."

Jimvela, too funny.  I'm not that negative of NASA and I may certainly be wrong on any number of points but I am an optimist.  I believe that free markets, following government sponsored exploration is THE best model to open up the solar system.  SpaceX and Bigelow have the best opportunity for than at any time in history.  I may be wrong but I think we all hope I'm not.


Coach

[coach]

"Merlin 1c 92k lb thrust is the block I design with the plump upgrade will increase the thrust to 102k lb, block II."

Are they planning on using the upgraded turbo pump on the F9 Heavy?  SpaceX just updated their F9 Heavy specs page and I was curious if this new pump was a part of it.

Coach

[Comga]

coach - 15/11/2007  7:57 PM

"With or without the best of intentions, some parts of NASA will undercut the commercial market."

Who will be able to live in these NASA inflatables?  Only NASA astronauts.  Who will do scientific research in them?  Only NASA employees.  Bigelow will build his inflatables "across the street" from NASA's and will use professional astronauts along with scientists from all backgrounds and tourists from anywhere in the world. ....

This does not refute my contention.  There is an institutional bias, for good and bad reasons, against what you think is the "best way".   If it is a good idea, and cost reductions are small contributors to "good" at NASA, they will bring it "in house" to a vendor under their direct control.

[meiza]

I'm curious how the F9 has comparable performance to Atlas V 401 even though their first stage has same thrust but less performance and the upper stage is much heavier too... They must have a better mass fraction.