Talk:RP-1

Power Density / Specific Impulse
Here, the article states that RP-1 is both considerably less powerful than liquid hydrogen, and significantly more powerful! Could somebody please make this more comprehensible to the lay wiki-crawler who knows nothing about rocket science? Thank you! (^o^)V --unsigned by 62.252.192.7 at 12:51, 10 December 2004.


 * PR-1 has a lower specific impulse (Isp) then hydrogen, this is basically a mark of efficiency of how much thrust can be made per mass of fuel.
 * Now Imagine you were building a rocket engine, you need to mix fuel and oxidizer together and burn it to make thurst, The more fuel you mix at once the more thrust per mass of rocket engine, the higher the fuels Isp the more thrust per mass of fuel. So natural your going to want a rocket engine that can burn a huge amount of fuel at once thus producing huge a amount of thrust from a very light weight engine, as well has use a fuel that has a high Isp so you need less fuel and thus less mass. Hydrogen has the highest Isp so it got the fuel mass problem cover, but hydrogen very low density means that a large volume of fuel must be pump into the rocket engine, meaning a engine which produce less thrust per weight of the engine. RP-1 with is very high density means a small volume of must be pumped into the engine, thus smaller ligher engine. Thus RP-1 can produce greater thrust per volume then hydrogen, but Hydrogen produces greater thus per mass. --BerserkerBen 00:59, 20 December 2005 (UTC)


 * To summarize the detailed description above, hydrogen is more energy dense with respect to mass (1 kg of hydrogen contains more "energy" than 1 kg of RP-1). However, since hydrogen has such low density, 1 kg of hydrogen takes up a lot more room than 1kg of RP-1. Therefore hydrogen is not as energy efficient with respect to volume. For spacecraft applications mass is generally more important, but volume is definitely a concern as well as you would need bigger (thus heavier) tanks (not to mention cryogenically capable) to use hydrogen over RP-1.
 * --unsigned by 128.158.214.39 at 21:52, 6 August 2007

chemical formula
What is the chemical formula for RP-1 (kerosene)? — Preceding unsigned comment added by 132.198.251.60 (talk) 21:54, 9 May 2012 (UTC)


 * I believe it is an extensive mix of many different alkanes, as with nearly all petroleum fuels. The difference being mostly a much lower sulfer content (and probably many other undesirable impurities) than cheaper and less rare petroleums. This is touched on in the Fractions and formulation section. 24.79.109.110 (talk) 23:19, 26 July 2012 (UTC)

Specific Impulse as exhaust velocity vs momentum
In the comparison with other fuels section, there are a few sentences early on directly equating exhaust velocity with specific impulse. While these are certainly related, the paragraph appears to be saying that velocity is more important than momentum, which (as far as I understand physics) is completely ridiculous. I believe the purpose of that paragraph can still be served by removing the 2nd through 5th sentences, and reworking the rest regarding oscillating modes between atoms. Maybe an additional mention of lower combustion temperatures vs. hydrogen? 24.79.109.110 (talk) 16:58, 23 July 2012 (UTC)
 * As a characteristic value, velocity is better. You can get more momentum by increasing the (mass) flow rate. You could use momentum per unit mass, but then you get ... velocity!  Specific impulse is thrust divided by (weight per second) of fuel (and oxidizer), which has dimensions of time (seconds).  If you instead used thrust/(mass per second) of (fuel and oxidizer) you get a velocity. Ideally, this is the velocity of gases exiting the engine, which is specific impulse (in seconds) times standard g.  (That is, little g.)  Jet engines have a similar quantity, but only based on fuel used not oxidizer (air). In this case, the velocity doesn't have much meaning. Gah4 (talk) 04:45, 6 August 2020 (UTC)
 * As a characteristic value, velocity is better. You can get more momentum by increasing the (mass) flow rate. You could use momentum per unit mass, but then you get ... velocity!  Specific impulse is thrust divided by (weight per second) of fuel (and oxidizer), which has dimensions of time (seconds).  If you instead used thrust/(mass per second) of (fuel and oxidizer) you get a velocity. Ideally, this is the velocity of gases exiting the engine, which is specific impulse (in seconds) times standard g.  (That is, little g.)  Jet engines have a similar quantity, but only based on fuel used not oxidizer (air). In this case, the velocity doesn't have much meaning. Gah4 (talk) 04:45, 6 August 2020 (UTC)

Should we explain cost?
My understanding is that one of the main reasons to use RP-1 is because of the significantly lower cost than some other propellants, I believe people reading this article might be interested in a rough cost comparison between RP-1 and other fuels like automotive gasoline and jet fuel. 174.76.23.195 (talk) 00:14, 1 July 2015 (UTC)

comparison with diesel
What happens if you fill RP-1 into a diesel car? Judging from what the article currently reveals, my guess is that RP-1 should be well within the specs for diesel fuel and therefore should work without problems. Or maybe there are some important additives for combustion engines missing? It would be nice to get an authoritative answer for that, and I think readers of the article would also find this interesting. --BjKa (talk) 14:56, 18 August 2016 (UTC)

Air pollution
Why would an RP-1/LOX engine produce nitrogen oxides but an LH2/LOX engine not do so, as suggested at the end of RP-1?125.254.43.66 (talk) 03:54, 2 December 2016 (UTC)
 * I was about to ask the same question, but you got there first (by a few years). For a jet engine, yes. I suppose for fuel rich, there could be some combustion with air, but I think at lower temperatures. It is the higher temperatures that generate NOx in internal combustion engines. Gah4 (talk) 04:47, 6 August 2020 (UTC)
 * Yes, the heat of LH2/LOX combustion produces some nitric oxide. Praemonitus (talk) 14:33, 6 August 2020 (UTC)
 * The article says that RP-1 does, and LH2 doesn't. For cars, it is the peak temperature is high enough to generate the NOx, and then cool fast enough that the N2 doesn't reform. (I forget the temperature, though.) Cars use EGR to reduce the temperature enough. So, for rockets, the question is how much air mixes in when it is still hot enough, and does it cool fast enough. And why RP-1 but not LH2? Gah4 (talk) 16:45, 6 August 2020 (UTC)
 * From this EPA paper it seems that 1300C is the magic temperature. Presumably when air starts to mix with exhaust, it will cool down, from the outside in. Gah4 (talk) 19:34, 6 August 2020 (UTC)
 * No the article says that the combustion of hydrogen produces water, which it does. It also does not claim that the reaction creates no pollution; only less. Presumably it is the thermal output that causes nitrogen and oxygen in the atmosphere to react. In that sense it's an indirect product. Praemonitus (talk) 20:55, 6 August 2020 (UTC)
 * It says: while hydrogen (H2) reacts with oxygen (O2) to produce only water (H2O), with some unreacted H2 also released., which seems to leave out any other possibility. It also leaves out unreacted O2. The sentence before, for hydrocarbons, mentions NOx. Combustion in air, above 1300C, generates NOx. If cooled fast enough, it doesn't get a chance to go back to N2. For rockets, it would have to be above 1300C when air got mixed in, which I don't know about. For gasoline engines, it is indirect. It seems that coal and diesel can have nitrogen in before combustion. Gah4 (talk) 23:58, 6 August 2020 (UTC)
 * Well the whole point of this article is to discuss RP-1. All that paragraph needs to demonstrate is that the LOX/LH2 reaction is cleaner, and as written appears correct. If you want to expand on the possibilities, I suggest starting with LOX/LH2. Praemonitus (talk) 01:57, 8 August 2020 (UTC)
 * From this EPA paper it seems that 1300C is the magic temperature. Presumably when air starts to mix with exhaust, it will cool down, from the outside in. Gah4 (talk) 19:34, 6 August 2020 (UTC)
 * No the article says that the combustion of hydrogen produces water, which it does. It also does not claim that the reaction creates no pollution; only less. Presumably it is the thermal output that causes nitrogen and oxygen in the atmosphere to react. In that sense it's an indirect product. Praemonitus (talk) 20:55, 6 August 2020 (UTC)
 * It says: while hydrogen (H2) reacts with oxygen (O2) to produce only water (H2O), with some unreacted H2 also released., which seems to leave out any other possibility. It also leaves out unreacted O2. The sentence before, for hydrocarbons, mentions NOx. Combustion in air, above 1300C, generates NOx. If cooled fast enough, it doesn't get a chance to go back to N2. For rockets, it would have to be above 1300C when air got mixed in, which I don't know about. For gasoline engines, it is indirect. It seems that coal and diesel can have nitrogen in before combustion. Gah4 (talk) 23:58, 6 August 2020 (UTC)
 * Well the whole point of this article is to discuss RP-1. All that paragraph needs to demonstrate is that the LOX/LH2 reaction is cleaner, and as written appears correct. If you want to expand on the possibilities, I suggest starting with LOX/LH2. Praemonitus (talk) 01:57, 8 August 2020 (UTC)
 * Well the whole point of this article is to discuss RP-1. All that paragraph needs to demonstrate is that the LOX/LH2 reaction is cleaner, and as written appears correct. If you want to expand on the possibilities, I suggest starting with LOX/LH2. Praemonitus (talk) 01:57, 8 August 2020 (UTC)

Copyright infringement
Most of this article is copied verbatim from John D. Clarke's "Ignition!"
 * ❌ doesn't appear to be a copyvio.   Dr Strauss   talk   08:59, 24 October 2017 (UTC)

The problem of coking in high-performance engines with RP-1 fuel
The article briefly mentions "the problem of non-dissociated petroleum residue" (coking) in RP1-fueled engines, but does not really explicate the problem of coking, or how this is causing a large amount of engine research and development to move to other fuels (like the recent large upswing in methalox rocket engines like Raptor and BE-4). The term "coking", although widely mentioned in rocket engine and jet engine engineering literature, is not even mentioned in the Wikipedia article at all in the present version.

This paper for publication by AIAA—Decomposition Measurements of RP-1, ...—and this extensive set of data that underlie it—DECOMPOSITION KINETICS OF THE ROCKET PROPELLANT RP-1 AND ITS CHEMICAL KINETIC SURROGATES, that came from this 2012 Mechanical Engineering PhD dissertation by Megan E. MacDonald—would help improve the coverage of coking in the article.

"High-performance regeneratively cooled engines require fuel that not only performs well as a propellant but also acts as a coolant for the engine. Operating temperatures of the engines in these high-performance vehicles are continually increasing and are reaching the point at which research into the formation of coke (solid carbonaceous deposits) in the cooling channels, which restricts the flow and hinders the heat transfer process, has become critical. Three main mechanisms of coke formation have been described in the literature: oxidative, catalytic, and pyrolytic [1-5]. Here, the focus is on understanding the initial gas-phase kinetic processes that lead to the formation of pyrolytic coke. This coking mechanism is predominant at temperatures above 825 K and occurs when the fuel is heated enough to decompose into reactive fuel radicals, leading to the eventual formation of coke [3]. There is a need to characterize the high-temperature decomposition rates of both rocket fuels and the fuel surrogates used to simulate the kinetic behavior of these fuels."

Good stuff. Would definitely facilitate improvement of this article on RP-1 if someone wants to parse the abstract and introduction and conclusions, and then write up a section that better explicates coking with RP-1. Cheers. N2e (talk) 11:24, 23 November 2018 (UTC)

Request to change/remove section
{request edit}} Price section of page The language of the section fails to maintain a neutral tone. Citations taken from a Quora article, with no historical price trend information available. -sayer2681