Talk:Raptor (rocket engine)
|WikiProject Spaceflight||(Rated Start-class, Mid-importance)|
- 1 Raptor is an engine, not a rocket stage.
- 2 Cleanup
- 3 Hydrogen?
- 4 "MCT is not a engine. Raptor is the next engine."
- 5 Article move
- 6 Substantially more information released to the public, October 2013
- 7 I've got a possible citation for the Raptor specific impulse, if some guesswork is allowed
- 8 Liquid methane
- 9 vacuum specific impulse is different from the specific impulse of a vacuum optimized version
- 10 New thrust numbers
Raptor is an engine, not a rocket stage.
SpaceX's web site and presentations mention the raptor as a rocket engine, not a rocket stage.I suppose it could be both, though. Recommend this article be renamed Raptor (rocket engine). I see that there are web pages that mention it as being an upper stage, but these seem to be mistaken, and SpaceX's own web site would be a much more reliable source for what it actually is. --126.96.36.199 (talk) 15:13, 3 November 2010 (UTC)
- That seems to be correct, it is an engine and not a rocket stage. Let's wait another week or two to see in anyone else wants to weigh in. If not, let's just rename the article per proposal by 188.8.131.52 above. N2e (talk) 05:43, 13 December 2010 (UTC)
- I cant find mention of Raptor as an engine on SpaceX's web site can you give a link. If Raptor is the name of the engine then it would make sence to change the name but as Raptor would use diffent fuel to the merlin it would need a new stage which would proberly carry the same name so the stage should still be mentioned. 184.108.40.206 (talk) 01:10, 22 December 2010 (UTC)
- I don't know of a source still available from the SpaceX website; SpaceX may have gone proprietary on some of their current advanced plans. The source in the article, from the AIAA Innovations in Orbit: An Exploration of Commercial Crew and Cargo Transportation conference held in June 2009, is the source I am familiar with, and where I first heard of the Raptor concept design. I'm glad the AIAA caught the talk on video. I have captured the quotation: "[SpaceX has] begun initial design of the Raptor LOX/Hydrogen upper stage, which dramatically increases payload performance."
- But the important note to make is we still have no (zip, zilch, nada) source that indicates that "Raptor" is a rocket stage. We could speculate on the name for the stage, but this is Wikipedia so we can't, and should just go with what we have verifiable information for. So I think it is time to rename the article. Looking at other rocket engine articles, I would propose: Raptor (rocket engine). N2e (talk) 06:25, 22 December 2010 (UTC)
I've made a few edits to begin to cleanup the article, including requests for more up-to-date information on the formal status of this development(?) or conceptual(?) program. Much more is needed. N2e (talk) 05:48, 13 December 2010 (UTC)
- Could be. But it is not clear that any Methane engine they might be working on is the Raptor, and therefore may not belong in this article. If you have a source, please edit the article and update it with the facts. Cheers. N2e (talk) 04:45, 5 September 2012 (UTC)
"MCT is not a engine. Raptor is the next engine."
Elon Musk, November 2012: "MCT is not a engine. Raptor is the next engine. More details to be revealed next year!".
Looks like this supports the discussion above, from 2010, and the article should be renamed. As well, this info will need to be reflected in the article body. Cheers. N2e (talk) 07:10, 21 November 2012 (UTC)
- Here's a timelink to where in the video he says that quote.--Craigboy (talk) 08:35, 8 March 2013 (UTC)
more press on the same topic
- Notes from an attendee at Musk's talk
- Musk goes for methane-burning reusable rockets as step to colonise Mars, David Todd, Flightglobal Hyperbola, 20 Nov 2012.
Based on previous discussions on this Talk page since 2010, and now recent reliable sources confirming both that the SpaceX "Raptor" development project is an engine, not an upper stage—and that it will utiilize Methane/LOX as a propellant, not LH2/LOX—I am going to move the article to Raptor (rocket engine) from its existing article name Raptor (rocket stage). N2e (talk) 03:17, 22 November 2012 (UTC)
Substantially more information released to the public, October 2013
In recent news releases, a good bit of new information has been publically released by SpaceX about the Raptor engine, and the whole methane-based Raptor concept objective (inner solar system travel and exploration and colonization of Mars). I have updated the article with several aspects of the new information: mostly technical specs, testing plans, and the launch vehicle objectives of the new methane powered rockets.
Having said that, there is more info in the Space News article, on the financials for the Mississippi test facility, and more, should other editors want to read it, and consider its use in the article. Cheers. N2e (talk) 02:26, 26 October 2013 (UTC)
I've got a possible citation for the Raptor specific impulse, if some guesswork is allowed
"I realized that a methane-oxygen rocket engine could achieve a specific impulse greater than 380." - Elon Musk
- I'd go ahead and add it to the article, as the current citation does not support the 380 claim at all. N2e (talk) 05:38, 26 November 2013 (UTC)
Why not refer to liquid methane as LCH4 for short? The following paper does so: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090004695.pdf — Preceding unsigned comment added by 220.127.116.11 (talk) 07:09, 13 June 2014 (UTC)
vacuum specific impulse is different from the specific impulse of a vacuum optimized version
The first stage version would have a sea level ISP of 321s and a vacuum ISP of 363s. The 380s number is for a physically different engine, which the citations are correct about, but this article was not. A vacuum optimized Raptor engine would be required for 380s ISP. Vacuum optimization means a larger expansion nozzle so the gasses expand more completely. The Merlin article makes this distinction correctly - sea level ISP is 282s, vac ISP is 311s, and the vacuum version of the engine is 340s. I don't think it's correct list stats side by side for physically different versions of the engine without making the distinction. ArbitraryConstant (talk) 23:30, 31 December 2014 (UTC)
- I believe I understand your technical point, and it is a good one. If you can think of a good way to present that reality in the article, go for it. As long as there are verifiable reliable sources for each number, and those sources clarify which engine config the isp number is for, I see no problem with being explicit about this detail. N2e (talk) 05:21, 1 January 2015 (UTC)
New thrust numbers
From 2015-01-05 Reddit AMA with Elon Musk,
- Q: Has the Raptor engine changed in its target thrust since the last number we have officially heard of 1.55Mlbf SL thrust?
- A (Musk): Thrust to weight is optimizing for a surprisingly low thrust level, even when accounting for the added mass of plumbing and structure for many engines. Looks like a little over 230 metric tons (~500 klbf) of thrust per engine, but we will have a lot of them :)
From same AMA:
- Q: In your recent MIT talk, you mentioned that you didn't think 2nd stage recovery was possible for the Falcon 9. This is due to low fuel efficiency of kerosene fuel, and the high velocities needed for many payloads (high orbits like Geostationary orbit). However, you also said that full reusability would be possible for the Mars Colonial Transporter launch vehicle.
- What have you learned from flights of Falcon 9 that taught you
- a) that reuse of its second stage won't be possible and
- b) what you'll need to do differently with MCT to reuse its second stage.
- A (Musk): Actually, we could make the 2nd stage of Falcon reusable and still have significant payload on Falcon Heavy, but I think our engineering resources are better spent moving on to the Mars system.
- MCT will have meaningfully higher specific impulse engines: 380 vs 345 vac Isp. For those unfamiliar, in the rocket world, that is a super gigantic difference for stages of roughly equivalent mass ratio (mass full to mass empty).
I don't know how and if this information should be incorporated into the article. Perhaps as a footnote to existing numbers until something more official is released. -- ToE 12:12, 6 January 2015 (UTC)