Wikipedia:Reference desk/Archives/Science/2017 February 27

= February 27 =

Why are there so few jet engine manufacturers?
It seems that jetliners from different aircraft manufacturers almost always use jet engines from a small group of manufacturers: GE, Pratt & Whitney, and Rolls-Royce. What is it about designing and building jet engines that is so difficult or expensive that even big aircraft manufacturers don't want to develop their own? --100.34.204.4 (talk) 02:37, 27 February 2017 (UTC)


 * It was decided in the 1930s that United States antitrust law did not allow airplane manufacturers to make the own engines (or to own their own airlines, either&mdash;see United Aircraft and Transport Corporation). I presume this still applies and would also prevent non-US companies such as Airbus, Bombardier, or Embraer from selling planes to US airlines if they had made the engines for them.  And I presume that without the US market, they would be unwilling to manufacture engines.  But my presumptions could be wrong; citations welcome.  As to how difficult it is, this answer seems to be based on actual knowledge.


 * None of this addresses the question of why there are so few engine manufacturers. I think (here I go presuming again) it is because engines are so expensive and complicated nowadays that new companies don't want to compete against the existing ones. --76.71.6.254 (talk) 02:56, 27 February 2017 (UTC)


 * And Rolls Royce isn't even making that much profit off its jet engines . I can't fin the specific answer for you, but it's usually dictated by economies of scale. This is general background, and I'm not certain this is the case here: In brief, the output of a given firm, in terms of widgets per year, gets cheaper per widget to a point. Up to that point, a large firm can undercut the price of a smaller firm. If the most efficient scale of production is a third the size of the entire market, then three firms can turn a profit (or one firm can operate three factories). If the most efficient scale is larger than the market, only one firm can turn a profit. It is widely thought, for instance, that the global market for large commercial airplanes can only support a single firm, and the most efficient scale is unreachable . That one firm would be Boeing, with Airbus only continuing to exist thanks to sponsorship by European governments and carriers, who don't like the idea of one company making every airplane. Someguy1221 (talk) 02:58, 27 February 2017 (UTC)
 * And forgot to mention, companies that try to enter the engine market tend to get purchased by an existing company . Someguy1221 (talk) 02:58, 27 February 2017 (UTC)


 * That does not compute. Boeing gets bigger State subsides than Airbus ever did. , . So Boeing  is able to undercut  Airbus by selling at below 'true' cost without going bankrupt.--Aspro (talk) 17:31, 27 February 2017 (UTC)


 * Boeing and Airbus have been arguing forever over who gets bigger subsidies, and we actually have a section on it in Competition between Airbus and Boeing. It's actually difficult to compare since both companies get their subsidies in different fashions. Boeing's subsidies are in the form of tax breaks and tax credits (and according to airbus, military contracts indirectly subsidies civilian operations). Airbus receives subsidies in the form of government-backed loans at interest rates far below the market rate. Boeing would certainly argue that the magnitude of Airbus' subsidies far exceed its own. As for who would die without subsidies, I find it compelling (to me anyway), that Boeing's subsidies usually arise as states race to the bottom while fighting over where Boeing will put a factor they had always planned on building; while on the other hand, Airbus is receiving below-market-rate loans to invest in something they may have never built otherwise. Someguy1221 (talk) 01:34, 28 February 2017 (UTC)


 * Barriers to entry may be relevant. StuRat (talk) 03:04, 27 February 2017 (UTC)


 * Also Monopolistic competition. ←Baseball Bugs What's up, Doc? carrots→ 03:11, 27 February 2017 (UTC)


 * More of an oligopoly. StuRat (talk) 03:47, 27 February 2017 (UTC)
 * Monopoly isn't relevant when there's three major manufacturers. The above linked oligopoly is indeed correct. The aviation jet engine (don't forget about marine turbines etc) market is largely determined by the plane manufacturers, as they choose which engine, or choice of which engine, they offer with their planes. Fgf10 (talk) 08:12, 27 February 2017 (UTC)
 * Not monopoly, but monopolistic competition: A few large firms controlling the market. ←Baseball Bugs What's up, Doc? carrots→ 08:44, 27 February 2017 (UTC)
 * The jet engine market is weird, since the three companies often work together in mix and match ways - Engine Alliance is GE and P&W, International Aero Engines was originally RR and P&W, and RR and GE worked together on the (failed) General Electric/Rolls-Royce F136, and then there are other smaller companies like the German MTU Aero Engines and the Japanese Japanese Aero Engine Corporation, who manufacture engines for the big three. So it's not really that there are very few engine manufacturers, exactly, but rather, the planemakers and airlines didn't want to deal with so many competing engine standards, and so engine manufacturers coalesced. As for why no duopoly has emerged (like, for instance, how Boeing and Airbus now dominate airliner manufacturing), the manufacturers specifically try to ensure that engine manufacturers are always competing and avoid vendor lock-in by making at least two different engine types available for each model (and Boeing is now going further - Dreamliner engines are designed so that engines from Rolls Royce and GE can be swapped easily). There's a fairly detailed analysis of jet engine manufacturing industry here. Smurrayinchester 09:01, 27 February 2017 (UTC)


 * In the UK, there was only a single engine maker and a single large aircraft maker as the result of a deliberate government merger policy in the 1960s. Particularly for aircraft, this is generally seen as having had a bad effect overall, particularly for defence procurement.
 * In the engines field, this led to the dominance of one company and its approaches, abandoning several promising avenues of development as "not invented here". Bristol Siddeley in particular saw products that had achieved successful sales (the BS Pegasus) absorbed under the new banner but the next generation of development, the BS100 abandoned to save investment costs on a "foreign" site. The supposed advantages of avoiding duplication didn't happen as intended, and engines like the Armstrong Siddeley Viper still continued, alongside the superior BS Orpheus. This single organisation was supposed to increase its investment potential in new projects (such money actually came from a government pot anyway, and was handed out on the same per-project basis no matter who it went to). Yet it also made the whole edifice prone to a single-point failure, such as Rolls-Royce's bankruptcy after the RB211 fan blade problems. Some companies, such as de Havilland and their small helicopter turbooshafts, disappeared into licence building US designs.
 * Procurement of aircraft was particularly affected. The UK went from the 1950s and an era of innovation and competition between manufacturers to the monolithic doldrums of the 1970s when the answer to all military large aircraft designs was to stick some more new parts onto a Nimrod - which led to abandonment, abandonment and explosion, followed by buying from the US. Andy Dingley (talk) 10:17, 27 February 2017 (UTC)
 * While all that is true, the British aviation industry model of the early 1950s was not sustainable: "... there would be too many companies chasing a declining domestic market, and few had the potential to take on the American competition", from The Formation of the British Aircraft Corporation (BAC) 1957-61 (p. 2). That article is about the restructuring of the aircraft industry, but the aero engine sector was under the same pressures. The age when the RAF could purchase several types of aircraft to fulfil the same role had gone for ever. Alansplodge (talk) 13:43, 27 February 2017 (UTC)
 * But an industry based on two or three makers would still have supported some competition.
 * There was no problem post-war that there were "too many" makers, but rather that most of them were far too small. It was the small makers who needed to be merged, not Avro / Vickers / Handley Page / Shorts. What actually happened didn't even give one simple economic unit: the "factory in Belfast" was still known as Shorts and it was still thrown porkbarrel government contracts to keep the population sweet. Work was split between Brough or Warton according to political lobbying by unions and local MPs, not for some corporate economy of scale.
 * We got the worst of both worlds. Andy Dingley (talk) 15:04, 27 February 2017 (UTC)


 * To discuss the barriers to entry a bit more, starting up a new jet engine company would require a major influx of capital, with little promise of a quick return on investment. Compare this to starting a restaurant chain.  You could start with just a hot dog cart, then upgrade to a hot dog stand, then one restaurant, then 2, etc., until you have a major chain.  So, the initial investment can be quite modest, making for a low barrier to entry.  This is one factor explaining why there are so many restaurant chains, relative to the number of jet engine manufacturers. StuRat (talk) 15:15, 27 February 2017 (UTC)


 * In the restaurant scenario, selling the same hotdog as everyone else can work. In the engine scenario, selling the same engine as everyone else won't work. There is no reason to contract with the new guy in the market unless he has a phenomenal new design or he has plenty of money, drugs, and women lined up as kickback. 209.149.113.5 (talk) 17:58, 27 February 2017 (UTC)


 * True, but being able to do it cheaper would also be a selling point, and being based in nation X, which lacks it's own jet engine manufacturer, may get you more sales in that nation. Still, those barriers to entry are rather substantial. StuRat (talk) 18:02, 27 February 2017 (UTC)


 * Here's a fantastic set of charts from the USC Department of Aerospace Engineering: Merger and Acquisition History of Major US Aerospace Companies.
 * Nimur (talk) 19:15, 27 February 2017 (UTC)

Can earthling plants live on martian soil?
How is martian soil different from earthling soil? 166.216.159.83 (talk) 15:07, 27 February 2017 (UTC)
 * Wikipedia has articles titled Martian soil (for Mars) and simply Soil (which covers Earth's soil). You can read those and arrive at your own conclusions.  -- Jayron 32 15:14, 27 February 2017 (UTC)

How is Earth different from Mars? Can earthling life be transported to Mars? Does Mars have indigenous life adapted to the current conditions on Mars? 166.216.159.83 (talk) 15:12, 27 February 2017 (UTC)


 * Life on Mars is Wikipedia's article on this subject. -- Jayron 32 15:15, 27 February 2017 (UTC)


 * As far as current technology, we could only transport small life forms to Mars, such as plant seeds. Keep in mind that they need to be kept alive during the long trip, so may need some heat, even if those seeds are resistant to freezing.  Small animals, like mice, would require additional care, such as food, water, oxygen, and removal of solid, liquid, and gas waste (carbon dioxide).  Of course, this doesn't mean that those life forms would survive for long, once on Mars, but could be useful for experiments, to see if the transport method is safe. StuRat (talk) 15:23, 27 February 2017 (UTC)
 * Just to provide a link to what you're describing (ECLLS); life support system Fgf10 (talk)
 * Regarding differences, Mars has less gravity than Earth (37.6% as much), a very thin atmosphere (0.6% of the pressure on Earth - see Atmosphere of Mars) with little oxygen (but 96% CO2), no bodies of (liquid) water (see Water on Mars), and 43% as much sunlight (see Climate of Mars). What little water there is seems to be mostly frozen in the soil and as ice at the polar caps (Martian polar ice caps).  Temperatures also drop exceedingly low during the Martian night and winter, particularly in the southern hemisphere and poles.  The thin atmosphere also allows radiation and micrometeors to pass through which are blocked by Earth's atmosphere.  Of these differences, the lack of water is a major problem for all Earth life, and the lack of oxygen is a problem for Earth animals.  Any plan to bring life to Mars should include both plants and animals, as they can together form a closed system, where the plants provide oxygen and food for the animals, which in turn provide fertilizer, pollination, and carbon dioxide for the plants.  Far more plants would be needed than animals, both because of the higher metabolic rate of animals, but also because Mars has lots of carbon dioxide to start with, and little oxygen, so need many plants to convert it to O2.  This could also be done mechanically/chemically, but since the goal is to bring life to Mars, plants meet that goal better.  Also see Terraforming of Mars and colonization of Mars.   StuRat (talk) 15:28, 27 February 2017 (UTC)


 * Experiments meant to simulate Martian soil suggest that many plants could be grown on it.   You would need to provide water, more air, reasonable temperatures, and for most plants protection from ultraviolet light.  So basically, you would have to bring the soil inside and keep it in some kind of greenhouse, but the soil itself appears to be a viable foundation for agriculture.  Of course, that's based on what we think is in the soil based on the limited experiments we've sent over.  There could still be surprises that make growing plants harder than expected.  Dragons flight (talk) 16:02, 27 February 2017 (UTC)


 * Another difference is that Mars has a "sidereal rotation period" (day length) of 24h 37m 22s. Compared to the other diffs, this is minor, and shouldn't cause any problems. StuRat (talk) 22:25, 28 February 2017 (UTC)

See "Potatoes on Mars". It seems a bit overblown to me, what being simulated soil with artificial Earth conditions like water and air, but it addresses this question. Wnt (talk) 00:58, 2 March 2017 (UTC)

Metallic Hydrogen, Deuterium
Could metallic deuterium be formed? How would its properties differ from metallic hydrogen? Granted that the initially much lower abundance, and the necessary concentration and purification make difficulties, would it be easier after getting a good sized sample of pure deuterium to form the deuterium kind instead of the hydrogen kind, like somewhat lower pressure and higher temperature?144.35.45.64 (talk) 23:56, 27 February 2017 (UTC)


 * Not that many people study metallic deuterium compared to the corresponding state in hydrogen, but it is suspected to also reach this state at appropriate temperatures and pressures. However, the physical properties are expected to be measurably different (thermal expansion coefficient, specific heat, etc.) . Deuterium also, interestingly, has a different phase diagram from hydrogen . Someguy1221 (talk) 00:18, 28 February 2017 (UTC)
 * This paper talks more about the difference between the two isotopes, but like the others, doesn't say whether one will form a metal easier than the other. Someguy1221 (talk) 00:26, 28 February 2017 (UTC)


 * This is an interesting question. I would think the kinetic isotope effect would stabilize deuterium metal as it stabilizes other deuterium compounds - the heavier molecules jiggle back and forth less under the same heat, so they stay closer to the optimal positions for bonding, as far as I know.  But... I certainly don't know, so take that as a mere question. Wnt (talk) 00:44, 28 February 2017 (UTC)