TE
科技回声
首页24小时热榜最新最佳问答展示工作
GitHubTwitter
首页

科技回声

基于 Next.js 构建的科技新闻平台,提供全球科技新闻和讨论内容。

GitHubTwitter

首页

首页最新最佳问答展示工作

资源链接

HackerNews API原版 HackerNewsNext.js

© 2025 科技回声. 版权所有。

Why it's so hard to build a jet engine

444 点作者 mhb2 个月前

24 条评论

mppm2 个月前
One important aspect of modern jet engines that the article only mentions on the periphery are the materials engineering problems in the hot section. There are many metals (not to mention ceramics) that can survive 1000C temperatures, but there are not many that can permanently resist <i>creep</i> at these temperatures under high tensile loads. The <i>only</i> really viable class of materials at the moment are Nickel-based single-crystal superalloys that contain rare metals like Rhenium and Ruthenium. This comes with serious supply limitations and rather complex manufacturing, where the molten metal is solidified directly in the shape of a turbine blade from a single seed crystal. Fun stuff, in other words :)
评论 #43221684 未加载
评论 #43218151 未加载
评论 #43230131 未加载
评论 #43230543 未加载
评论 #43231309 未加载
评论 #43220420 未加载
bob10292 个月前
I&#x27;ve always been fascinated by the power density potential of the gas turbine. Especially the micro turbine class.<p>&gt; The MT power-to-weight ratio is better than a heavy gas turbine because the reduction of turbine diameters causes an increase in shaft rotational speed. [0]<p>&gt; A similar microturbine built by the Belgian Katholieke Universiteit Leuven has a rotor diameter of 20 mm and is expected to produce about 1,000 W (1.3 hp). [0]<p>Efficiency is not fantastic at these scales. But, imagine trying to get that amount of power from a different kind of thermodynamic engine with the same mass-volume budget. For certain scenarios, this tradeoff would be amazing. EV charging is something that comes to mind. If the generator is only 50lbs and fits within a lunch box, you could keep it in your car just like a spare tire. I think the efficiency can be compensated for when considering the benefits of distributed generation, cost &amp; form factor.<p>One of the other advantages of the smaller engines is that you can use techniques that are wildly infeasible in larger engines. For example, Capstone uses a zero-friction air bearing in their solutions:<p>&gt; Key to the Capstone design is its use of air bearings, which provides maintenance and fluid-free operation for the lifetime of the turbine and reduces the system to a single moving part. This also eliminates the need for any cooling or other secondary systems. [1]<p>[0] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Microturbine" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Microturbine</a><p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Capstone_Green_Energy" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Capstone_Green_Energy</a>
评论 #43218062 未加载
评论 #43223190 未加载
评论 #43215641 未加载
评论 #43226885 未加载
评论 #43219575 未加载
评论 #43220173 未加载
评论 #43223195 未加载
评论 #43232061 未加载
jmward012 个月前
The physics of gas turbine engines is one reason I am really excited about electric aviation. People don&#x27;t realize that you are temp limited at altitude. They think the air is cold, but it is about getting mass through that engine so compressing that air to the density needed brings its temp way up. Electric doesn&#x27;t have that issue so electric engines could go much higher which means those aircraft could become much more efficient. People focus on the problem of putting enough energy into an electric airframe, but they don&#x27;t realie the potential massive efficiency gains that it can bring because of the physics of flight.
评论 #43214129 未加载
评论 #43214515 未加载
评论 #43214028 未加载
评论 #43214061 未加载
评论 #43215526 未加载
评论 #43219053 未加载
Animats2 个月前
And why they are so expensive.<p>General aviation is still running on pistons. Not because small jet engines can&#x27;t be built, but because they don&#x27;t get cheaper as they get smaller. 6-passenger bizjet sized engines seem to be the lower economic limit.<p>Williams tried and tried. They built good small jet engines, all the way down to jetpack size, but those never got cheap.[1] There are &quot;very light jets&quot;, but the smallest in production, the Cirrus Vision Jet, is around US$2 million.<p>[1] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Williams_International" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Williams_International</a><p>[2] <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Very_light_jet" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Very_light_jet</a>
评论 #43224025 未加载
评论 #43223086 未加载
评论 #43225992 未加载
adiabatichottub2 个月前
For anybody interested in gas turbine engineering, I recommend Gas Turbine Theory by Cohen &amp; Rogers.<p><a href="https:&#x2F;&#x2F;archive.org&#x2F;details&#x2F;gasturbinetheory0000sara" rel="nofollow">https:&#x2F;&#x2F;archive.org&#x2F;details&#x2F;gasturbinetheory0000sara</a>
sitharus2 个月前
A very good article, but I was disappointed to see the misunderstanding about the de Havilland Comet failures repeated<p>&gt; fatigue failures around its rectangular windows caused two crashes, resulting in it being withdrawn from service<p>While the accident investigation reports refer to &quot;windows&quot;, which really doesn&#x27;t help matters, the failure point was the ADF antenna mounting cutout. The passenger windows had rounded corners and did not fail in service.<p>The Comet was not withdrawn from service, they re-engineered and launched the Comet 4 (with oval windows, but that choice was to reduce manufacturing costs) in 1958, but the Boeing 707 was introduced that year and the DC-8 in 1959, ending the Comet&#x27;s status as the only in-service jet airliner it held between 1952 and the grounding of the Comet 1 in 1954. The Comet 4 continued to fly in revenue service until at least the mid 1970s with lower-tier airlines.<p>The decision to bury the engines in the wings was one of the deciding factors for airlines - engines in nacelles are easier and cheaper to service and swap if required. Re-engining the Comet 4 to new more efficient turbofan engines the DC-8 and Boeing 707 introduced in 1960 and 1961 respectively required a new wing, but a podded engine was much easier to swap on to an existing airframe and this was done for many of the Boeing and Douglas aircraft.<p>The last Comet-derived aircraft - the Hawker Siddeley Nimrod - flew until 2011 in the RAF. They did look at upgrading them with new wings and avionics, but the plan was scrapped when they discovered that in the grand tradition of British engineering every fuselage was built slightly differently and they couldn&#x27;t make replacement parts to a standard plan.<p>Anyway that&#x27;s my rant in to the void today :)
评论 #43217076 未加载
anon_cow11112 个月前
For young aspiring engineers here who may read this and just like the sound of &quot;building jet engine&quot;, look into building a pulse jet first.<p>They&#x27;re extremely easy to build, having no moving parts, and only requiring some steel tubing, a welder and a large propane tank. I&#x27;ve already done it and can attest to this being true.<p>The &quot;best&quot; part is that they&#x27;re incredibly, <i>obnoxiously</i> loud. Like wear earplugs and ear muffs at the same time loud. Efficiency isn&#x27;t great, you can expect maybe 20-100 lbs thrust from larger models but I suppose that&#x27;s more than enough for &quot;let&#x27;s grab an old bicycle and do something really stupid&quot; (oh and look pulsejets up on youtube for sure, it&#x27;ll open up a whole world for you in under 20 minutes)
评论 #43226189 未加载
avmich2 个月前
&gt; Developing a new commercial aircraft is another example in this category, as is building a cheap, reusable rocket.<p>Cheap rockets can be vastly simpler than turbojet engines. Reusability (I&#x27;m talking about reusability of an orbital rocket, suborbital reusable rockets can be rather simple, as e.g. Armadillo Aerospace and Masten Space achievements show) adds a lot to the order, but increasing the size the square-cube law improves things to an extent.
评论 #43220637 未加载
评论 #43220856 未加载
评论 #43218907 未加载
smitty1e2 个月前
&gt; Building the understanding required to push jet engine capabilities forward takes time, effort, and expense.<p>This occurs in a broader cultural context. A society that dreams, enjoys science fiction, rewards hard study of advanced topics and so forth, can produce the work force to staff companies capable of going to the stars.<p>Let us encourage that.
评论 #43218961 未加载
wyager2 个月前
What&#x27;s beautiful to me is that that combustion turbines have the simplest possible thermodynamic cycle in theory (a steady input flow of X fluid&#x2F;sec at pressure P, and a steady output flow of Y&gt;X fluid&#x2F;sec at pressure P), yet it turns out to be one of the most complex cycles to harness in practice!
评论 #43218408 未加载
alkonaut2 个月前
&gt; There’s no point in designing a new engine if it doesn’t significantly improve on the state of the art<p>Oh but there is. I would love to see more European alternatives to US designs even at 5% less efficiency and power. Surely it can’t be <i>that</i> expensive to create an engine in 2025 similar to the state of the art 2005, when you have all the hindsight plus unlimited access to the original design?<p>Events of this week show that this will be very important.
评论 #43221291 未加载
评论 #43230305 未加载
评论 #43224073 未加载
评论 #43228871 未加载
评论 #43229488 未加载
orbital-decay2 个月前
One important point is missing from this: building a cheap and good engine is not enough, there are more companies and industries that can do this than it seems. But you also need the maintenance and logistics network, with a ton of professionals trained for your engine type in particular. And for that you need to penetrate the market that is already captured. This is what stopping the most.
I_dream_of_Geni2 个月前
Funny, if you mouse over the graph of transistor costs, they become free in 2005! Cool!
评论 #43217671 未加载
divbzero2 个月前
Related:<p><i>See Thru Jet Engine [video]</i> - <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=32145297">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=32145297</a> - July 2022 (70 comments)
evnix2 个月前
I feel, What&#x27;s more harder are the jet engines on fighter planes. These are usually a decade or two ahead in terms of advancements. The technology here trickles down to commercial jet engines slowly. Things like Metullargy for blades etc are a closely guarded secret. China and India are pouring billions into research just to get theirs close to even the lower end of what GE has to offer.
评论 #43218110 未加载
drysine2 个月前
&gt;Depending on how you count, there are just two to four builders of large commercial aircraft (Airbus, Boeing, Embraer, and now COMAC).<p>Where is Russian Sukhoi?
评论 #43217831 未加载
评论 #43217900 未加载
paulpauper2 个月前
It&#x27;s hard not because the technology is so special , but because the tolerance for errors is so small . Jet failure can mean loss of many lives and little room to rectify the situation in flight ,whereas an automobile or train engine failure is a more manageable situation.
maxglute2 个月前
May countries got domestic turbojet running, but most engine projects fail because there wasn&#x27;t political will eat the billions to keep a competitive program going, especially as complexity increase in turbofans.
DeathArrow2 个月前
I wonder if there aren&#x27;t other propulsion principles to pursue in modern aircrafts beside the jet engine.
gtirloni2 个月前
Aren&#x27;t these engine designs patented very heavily? How were clones popping up less than a decade later?
1024core2 个月前
How many countries make their own jet engines? US, UK, France ... anyone else?
评论 #43225235 未加载
评论 #43224340 未加载
评论 #43222744 未加载
anovikov2 个月前
It&#x27;s not all that hard to build a jet engine. Nazi Germany built them being constantly bombed, with actively sabotaging slave labor. Starving North Korea builds them. War-torn Ukraine builds them.<p>What&#x27;s hard is to build a competitive jet engine. And there, it happens naturally, by itself: the best marketable jet engine is the one where marginal increase of complexity and cost matches marginal fuel savings: buy simpler&#x2F;cheaper ones and you waste more money on fuel than you save buying the engine, buy a more complex&#x2F;expensive one and you don&#x27;t justify the costs with your fuel savings.<p>Because an engine runs for tens of thousands of hours - some over 100K hours - so 1% of performance improvement is worth ~1000 tons of fuel - there is a lot of complexity that can be pushed into the solution while still being profitable - and competition ensures this is the case.<p>That&#x27;s why it is incredibly hard to make a competitive jet engine.
评论 #43230041 未加载
gunian2 个月前
because it flies away
betimsl2 个月前
Material tolerances.