Author Topic: Syntin for the second stage of Falcon 9?  (Read 22047 times)

Online LouScheffer

  • Full Member
  • ****
  • Posts: 1818
  • Liked: 2336
  • Likes Given: 253
Syntin for the second stage of Falcon 9?
« on: 02/20/2014 05:31 PM »
Syntin is a synthetic hydrocarbon with slightly better properties than RP-1. It's a little denser and slightly higher ISP.  The main drawback seems to be that it has to be synthesized and is hence expensive.  But it seems like using it in the second stage could help Falcon 9 to GTO significantly.

Assuming current payload to GTO of 4.85t, empty second stage mass of 5t, and propellant load of 90t (200k lbs), and ISP of 340, then the delta-V provided by the second stage is:

340*9.8*ln( (4.85+5+90) / (4.85 + 5)) = 7717 m/sec

Syntin is about 5% denser.  Assuming you cool the LOX, you can get 8-9% denser on that, too. 

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20050203875_2005204553.pdf

So assume you can cram  95t of propellant in the current stage.  The Russian engines got about 8 sec more ISP with syntin.   So now you can loft 6t to GTO...

348*9.8*ln( (6+5+95)/ (6+5)) = 7726 m/s

So how expensive is syntin in industrial quantities? 

EDIT:  Oops, I wrote 940/948 for the ISP where I meant 340/348.  But this was a copying error and the results are correct.
« Last Edit: 02/22/2014 09:30 PM by LouScheffer »

Offline Proponent

  • Senior Member
  • *****
  • Posts: 5403
  • Liked: 943
  • Likes Given: 622
Re: Syntin for the second stage of Falcon 9?
« Reply #1 on: 02/20/2014 05:37 PM »
This is vague, but Bruce Dunn suggested in the mid-1990s that it would cost more than $100/kg.

But the project seems like a lot of work for a slightly greater capacity.

Offline cartman

  • Full Member
  • ****
  • Posts: 505
  • Greece
  • Liked: 485
  • Likes Given: 2505
Re: Syntin for the second stage of Falcon 9?
« Reply #2 on: 02/20/2014 05:43 PM »
Well if its $100/kg it is $9.5million for 95 tons plus the cost to test and qualify the fuel. Probably not worth it, at least in a launch that costs about $50million

Offline llanitedave

  • Senior Member
  • *****
  • Posts: 2142
  • Nevada Desert
  • Liked: 1317
  • Likes Given: 1548
Re: Syntin for the second stage of Falcon 9?
« Reply #3 on: 02/20/2014 05:46 PM »
Is there any indication that SpaceX has expressed interest in Syntin?
"I've just abducted an alien -- now what?"

Offline Lars_J

  • Senior Member
  • *****
  • Posts: 6161
  • California
  • Liked: 665
  • Likes Given: 195
Re: Syntin for the second stage of Falcon 9?
« Reply #4 on: 02/20/2014 05:46 PM »
Why would it be worth it, if it only provides a slight benefit?

Online LouScheffer

  • Full Member
  • ****
  • Posts: 1818
  • Liked: 2336
  • Likes Given: 253
Re: Syntin for the second stage of Falcon 9?
« Reply #5 on: 02/20/2014 05:50 PM »
Well if its $100/kg it is $9.5million for 95 tons plus the cost to test and qualify the fuel. Probably not worth it, at least in a launch that costs about $50million

Only half the propellant is Syntin, the rest is LOX, so it adds only 5 million or so.  And there are lots of commercial satellites in the 4.85t < M <6t mass range.  See this recent SeaLaunch example:

http://www.sea-launch.com/missions-q11373-Mission_Overview.aspx

The alternative (from the SpaceX view) would be to use a FH.  If you can compete for these same launches with an F9, it would save a lot of money, even if the fuel was a few million bucks more.

Offline Elmar Moelzer

  • Senior Member
  • *****
  • Posts: 3106
  • Liked: 553
  • Likes Given: 809
Re: Syntin for the second stage of Falcon 9?
« Reply #6 on: 02/20/2014 05:51 PM »
Hmm, pre chilling the RP1 might yield better results (might have other issues though).

Offline Danderman

  • Extreme Veteran
  • Senior Member
  • *****
  • Posts: 9601
  • Liked: 356
  • Likes Given: 460
Re: Syntin for the second stage of Falcon 9?
« Reply #7 on: 02/20/2014 05:59 PM »
This would work, but:

Sintin is really not available.

and

the engine has to modified to burn Sintin.

As a result, the IRR on learning to burn methane is probably higher.


« Last Edit: 02/20/2014 06:01 PM by Danderman »

Offline cambrianera

  • Full Member
  • ****
  • Posts: 1426
  • Liked: 307
  • Likes Given: 249
Re: Syntin for the second stage of Falcon 9?
« Reply #8 on: 02/20/2014 06:11 PM »
Only half the propellant is Syntin, the rest is LOX, so it adds only 5 million or so.

Actually less than one third; lowest O/F ratio for LOX and RP-1 is around 2.2 (most common around 2.5).
Oh to be young again. . .

Offline john smith 19

  • Senior Member
  • *****
  • Posts: 7405
  • Everyplaceelse
  • Liked: 1090
  • Likes Given: 7328
Re: Syntin for the second stage of Falcon 9?
« Reply #9 on: 02/20/2014 07:12 PM »
Well if its $100/kg it is $9.5million for 95 tons plus the cost to test and qualify the fuel. Probably not worth it, at least in a launch that costs about $50million

Only half the propellant is Syntin, the rest is LOX, so it adds only 5 million or so.  And there are lots of commercial satellites in the 4.85t < M <6t mass range.  See this recent SeaLaunch example:

http://www.sea-launch.com/missions-q11373-Mission_Overview.aspx

The alternative (from the SpaceX view) would be to use a FH.  If you can compete for these same launches with an F9, it would save a lot of money, even if the fuel was a few million bucks more.
Not really. IIRC Robobeat said Spacex are quoting NASA 16 tonnes to LEO and maybe half that to GTO for an expendable mission.

It sounds like Syntin is costing about the same as J10 (the synthetic fuel for cruise missiles) at about $100/lb.

RP1 is somewhere below $1/lb AFAIK. It's said that fuel costs are in the "noise" as far as launch costs are concerned but if that figure is right then Syntin is more expensive than any of the Amines.

The trouble with both  sub cooled propellants and advanced propellants is that they should be designed in before the LV is designed. That increased propellants weight means a) More thrust needed from the engines b)Slower acceleration,  so more stress on the vehicle, which means you either eat into your safety margins or strengthen the vehicle.

Similar issues with changing propellants. A 100x fold increase in propellant cost is pretty serious already but the logistics costs around it will cause even more cost and disruption.

The note on the LO2 densification article the OP mentions suggest that it's possible to build an HX with temperature difference across the exchanger of about 1 2/3K. That suggests that using standard boiling point LN2 you could cool any propellant to 79K (provided it's mp > 79k) without the trouble and expense of putting a large, high power vacuum pump on the exhaust to lower the BP of the LN2 (lowering the air pressure in the 2nd stage of the LN2 boiler by about 12 psi buys you about 10k).

Yes it's probably feasible. No it's probably not worthwhile  :(
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 32241
  • Cape Canaveral Spaceport
  • Liked: 10896
  • Likes Given: 325
Re: Syntin for the second stage of Falcon 9?
« Reply #10 on: 02/20/2014 07:27 PM »
Hmm, pre chilling the RP1 might yield better results (might have other issues though).

Heating works better.

Offline Elmar Moelzer

  • Senior Member
  • *****
  • Posts: 3106
  • Liked: 553
  • Likes Given: 809
Re: Syntin for the second stage of Falcon 9?
« Reply #11 on: 02/20/2014 08:15 PM »
Hmm, pre chilling the RP1 might yield better results (might have other issues though).

Heating works better.
I thought of pre chilling the RP1 for increasing the density. Wouldn't heating have the opposite effect?

Offline cambrianera

  • Full Member
  • ****
  • Posts: 1426
  • Liked: 307
  • Likes Given: 249
Re: Syntin for the second stage of Falcon 9?
« Reply #12 on: 02/20/2014 08:47 PM »
Hmm, pre chilling the RP1 might yield better results (might have other issues though).

Heating works better.
I thought of pre chilling the RP1 for increasing the density. Wouldn't heating have the opposite effect?
We are talking about the second stage, what's important is the specific energy, not the mass density.
Heating increases total energy (and combustion efficiency).
http://forum.nasaspaceflight.com/index.php?topic=5118.msg81521#msg81521
http://forum.nasaspaceflight.com/index.php?topic=5118.msg81574#msg81574
http://forum.nasaspaceflight.com/index.php?topic=5118.msg81581#msg81581
Oh to be young again. . .

Offline Dudely

  • Full Member
  • ***
  • Posts: 312
  • Canada
  • Liked: 109
  • Likes Given: 92
Re: Syntin for the second stage of Falcon 9?
« Reply #13 on: 02/21/2014 12:00 PM »
Man, rockets are hard.

Offline Elmar Moelzer

  • Senior Member
  • *****
  • Posts: 3106
  • Liked: 553
  • Likes Given: 809
Re: Syntin for the second stage of Falcon 9?
« Reply #14 on: 02/21/2014 01:36 PM »
I thought of pre chilling the RP1 for increasing the density. Wouldn't heating have the opposite effect?
We are talking about the second stage, what's important is the specific energy, not the mass density.
Heating increases total energy (and combustion efficiency).
Oh, that makes sense! Thanks!

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 28109
  • Minnesota
  • Liked: 7919
  • Likes Given: 5273
Re: Syntin for the second stage of Falcon 9?
« Reply #15 on: 02/21/2014 02:03 PM »
How much does heating really change the energy, though? Mass ratio is also really important.
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 vigleik

  • Member
  • Posts: 25
  • Liked: 4
  • Likes Given: 6
Re: Syntin for the second stage of Falcon 9?
« Reply #16 on: 02/22/2014 07:33 PM »
Let me point out a problem with the math in the original post: If you increase the mass of the second stage and the payload the delta v provided by the first stage goes down, and it looks to me like that wasn't taken into account. So the advantage is smaller than implied. (Exact numbers left as an exercise.)

Online LouScheffer

  • Full Member
  • ****
  • Posts: 1818
  • Liked: 2336
  • Likes Given: 253
Re: Syntin for the second stage of Falcon 9?
« Reply #17 on: 02/23/2014 05:40 PM »
Let me point out a problem with the math in the original post: If you increase the mass of the second stage and the payload the delta v provided by the first stage goes down, and it looks to me like that wasn't taken into account. So the advantage is smaller than implied. (Exact numbers left as an exercise.)
This is certainly true, and it reduces the advantage by about 30%, to about +800kg.  But on the other hand, SpaceX has announced that the regular kerosene powered model can loft 5.3t to GTO, more than the 4.85t previously claimed.  So a Syntin-fueled second stage could still put 6.1t into GTO.  That covers an awful lot of the comsat market.

Of course the FH can do this job easily.  But even if the stages are recoverable, it's still expensive.  Say the engines are $1M each, and can be used 10 times.  Then each use costs $100k.  The 18 extra engines cost at least 1.8 million in wear and tear alone, not to mention recovery and re-stacking.

Furthermore, a 4t comsat could be launched on a recoverable F9.1 mission with Syntin, but would need an expendable or a FH with kerosene.

Offline Lars_J

  • Senior Member
  • *****
  • Posts: 6161
  • California
  • Liked: 665
  • Likes Given: 195
Re: Syntin for the second stage of Falcon 9?
« Reply #18 on: 02/23/2014 08:40 PM »
Syntin is not 'KISS'. It only provides a minimal performance boost. Therefore it won't happen.

Online Robotbeat

  • Senior Member
  • *****
  • Posts: 28109
  • Minnesota
  • Liked: 7919
  • Likes Given: 5273
Re: Syntin for the second stage of Falcon 9?
« Reply #19 on: 03/11/2014 01:51 AM »
Syntin is not 'KISS'. It only provides a minimal performance boost. Therefore it won't happen.
Same with subcooling, which Musk suggests is likely?

I have no idea if syntin would be used, but something similar (and much cheaper) may be looked at by SpaceX if they need the performance. Which they probably do in order to reach all their performance goals. Subcooling sounds like a better idea, though, but I wouldn't put it past SpaceX to consider a reformulation of kerosene for the upper stage. A few seconds more Isp, a few percent better density, and you can now afford even upper stage recovery (or at least first stage recovery for an expanded customer list).

Propellant subcooling, carbon-carbon nozzle upper stage, possible other tricks like syntin for upper stage, maybe crossfeed for the Falcon Heavy... Pretty soon you've bought back much of the performance hit of reuse.
« Last Edit: 03/11/2014 01:55 AM by Robotbeat »
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

Tags: SpaceX