Kitty Hawk’s Cora

Sunday, March 18th, 2018

Kitty Hawk Corporation’s new Cora air taxi “is powered by 12 independent lift fans, which enable her to take off and land vertically like a helicopter” and has a range of “about 62 miles” while flying at “about 110 miles per hour” at an altitude “between 500 ft to 3000 ft above the ground”:


  1. Albion says:

    Pollution free, zero emissions, etc.

    Nice, but only in theory, because it avoids mentioning the production of components and elements that, er, relied on emissions and pollution to make. Let’s hope too that the maintenance of the planes does not need to use anything made with non-zero emissions.

  2. Jeff says:

    62 miles at 110 mph takes 34 minutes. Then you someehow have to recharge the batteries. How long does that take? And where do you do it?

    Maybe they have a way of swapping out batteries to get back in the air without waiting for a charge cycle. But this could only be done at specific locations, which implies that the taxi has to return to one of those locations after discharging passengers, which further lessens the usable range since you have to reserve enough charge to get to the swapping station.

    The power stored per pound for batteries is still very much less than fossil fuels. This is bad enough for an electric car. It’s much worse for an electric plane which has to lift all those heavy batteries, not just roll them along like a car does.

  3. Kirk says:

    Albion’s point is an excellent one that rarely, if ever, gets mentioned in all these “alternative energy” concepts.

    Once upon a time, I lived near a retired and very bored Boeing engineer, a man with several advanced degrees, a lot of experience in the aeronautical industry, many hours of time to fill, and a grudge. I got to know him by BS’ing with him at the local coffee place, and got my ear filled when I asked some questions about what he was working on with his laptop–His significant other had thrown him out of the house, you see, and he’d gone to the coffee place to work.

    He’d basically done a very thorough spreadsheet workbook outlining every single energy input into several “alternate energy” ideas, with emphasis on wind energy capture. His spreadsheet basically showed that by the time you got done returning the net energy used to manufacture and erect the then-current systems, circa 2003, you’d only start to break even on energy production about the time you were due to decommission the wind generator. If you rolled over the energy expenditures by recycling existing equipment, you only did a little bit better.

    Long story short, you ain’t running an advanced economy on “alternate energy” anytime soon, with the efficiencies we have. Maybe, just maybe, if someone makes some super-cheap room-temperature superconducting material, you might change that, but until something like that comes along, the costs of the systems outweigh the energy captured or produced. You’re actually better off burning the oil used to make the damn wind generators as fuel for a diesel generator–You get more efficiency out of it.

    Alternative energy is a scam, pure and simple. Anyone who does the math, and is half-way honest with it is going to find that out. You’re basically just cooking the energy books with these schemes–Even the damn corn for ethanol winds up costing more fossil fuels than you save, because of all the fertilizer, fuel, and other inputs that have to go into making the corn–And, that’s before you go through what it costs in energy to convert it to alcohol.

    The interesting thing is, even if you had unlimited free electricity from fusion and/or powersats, it would probably make a lot more sense to use that electricity to make artificial hydrocarbon-based fuels, instead of batteries. The weight of the fuel and the energy densities it can achieve really outcompete electric for a long damn time, like until we manage to attain near 100% efficiencies and lossless storage systems for it. An artificially produced hydrocarbon fuel in an internal combustion engine outdoes electric in terms of sheer efficiency and range for a huge part of the curves on these matters.

    But, we no longer do science and engineering in this world of ours–It’s all “feels”, all the damn time.

  4. Gaikokumaniakku says:

    “Long story short, you ain’t running an advanced economy on “alternate energy” anytime soon, with the efficiencies we have. …
    Alternative energy is a scam, pure and simple.”

    I would like to disagree at length. I don’t suppose I could persuade you to read a re-posting of other folks’ calculations if I were to post it at Vulture of Critique?

    I will assume that you won’t be willing to read a long re-hash so I will summarize. In brief, many Malthusians claim that EROEI cannot possibly be sufficient to run an advanced society on renewable energy. However, those Malthusians do not stop to reckon with the time factor. Return on investment is not just about magnitude of payoff; it is also about how much time is required for the payoff.

    Suppose you have an investment that pays off 20 to 1, but it takes 300 days to pay off. That sounds pretty good. Contrast that with an investment that pays off at 1.1 to 1, but it pays out every 3 days. If you were to reinvest everything, I think that pays off as (1.1)^100, which is slightly bigger than 20. But maybe total reinvestment is not reasonable. The point is that the “payoff” is just one number. The length of time required for the investment to pay off is the other key number.


    Now I have to websearch all those renewable energy links from startpage… I will post a link if I manage to locate the whole story.

  5. Mike in Boston says:

    Whether or not alternative energy is feasible for running the whole economy, if you are living in Hawaii (with sky-high utility rates) or somewhere tropical with a dysfunctional electric utility (Hawaiian readers can let me know if I am repeating myself), having cheap solar panels available sure seems nice, and it would be even better to have better batteries to store that energy at night.

  6. Graham says:

    The track record of the last 50 years does suggest that technology is not liable soon to make it possible to run a large industrial/postindustrial economy on alternative energy. Batteries, storage, the undeniably superior energy capacity of fossil fuels etc. etc. etc.

    Still, the research capabilities and to some degree financial surplus of these societies is significant and the topic has produced enough marginal payoffs, local projects, and niche uses to be well worth committing more efforts to. And wherever such sources can be used or storage improved, there’s a gain to something even if it’s just local survivability.

    Somebody gains from using these tools, and somebody profits from the R&D, marketing and manufacture. If they ever really make any of the promised breakthroughs, the winning idea will cease to be an “alternative” energy source very quickly.

    If not, then not. We need to invest with measured aspirations, but still invest.

  7. Graham says:

    If we’re lucky, we’ll get to some point at which we need fossil fuels neither for energy or for manufactured products, because both energy research and materials science will have found productive, economical and profitable replacements for oil, coal, and plastics.

    I know too little to be sure, but my impressions to date are that we might be closer on the materials than on the energy. Which is good, because I was terrified we wouldn’t solve that problem and would end up burning as fuel supplies we need to make our crap. And not-so-crap useful goods as well.

    Frankly, even given a set of assumptions about climate change, the failings [and some dishonesty] of the ways it has been presented the past 25-40 years, and the reality that some policies on offer are designed to advantage some states over others, there’s a huge mistake in too willingly ceding technological leadership in all these categories. “Green Jobs” was kind of a juvenile catch-all category with little semantic content and a lot of hope-inflation, but people are making money off this stuff. Plus, there’s always the chance of military applications…

    Actually, that bit about ways of presenting CC lingers for me. I remember the 1990s, when ever so many advocates for change more or less took the line that the apocalypse of the next 1-5-10 years could be staved off only by suicidal cuts NOW, and any primarily technological solution was pooh-poohed as wishful thinking by deniers. [I don't recall if that term was yet in vogue. But the line of argument was.] Now, lo, and technology is the answer after all.

    If this were still the argument of the 1990s, that admission would be the trigger for some kind of re-evaluation, reconciliation. Pity there’s so little goodwill left. Either way, I don’t expect us to move up to Kardashev Level I and stay there on the strength of fossil fuels and I haven’t been sold “alternative energy” can even keep us where we are now, yet. I’d like to see more pragmatism.

    Of course I’d also like home-use batteries for gadgets that don’t die with half their apparent charge still showing on a tester.

  8. Kirk says:


    The problem with those sites you don’t seem to recognize is that they’re run by advocates. So, they don’t include all the supporting data, just the bare assertions from other advocates that claim that the rate of return of energy goes as low as 4 years.

    Now, I’ve seen the spreadsheet that my engineer acquaintance, and still have it on an old hard drive. His numbers were actually cited, and based in real-world energy costs like what it took to produce a ton of aluminum in terms of mining, transportation of ores, refining, manufacture, and all the other little details. I know he captured everything going into it, and could see that for myself, along with the citations for where it was sourced from. As well, he actually used real-world energy production from specific wind projects, which the advocates will not tell you about–They say “Oh, it’s a six-megawatt generator…”, and then assume that the damn thing produces six megawatts continuously, all the time, with no down time or slack time for either inadequate or too much wind conditions. When you go digging into the actual power production numbers, the way he did, the actual “produced power” in the real world…? Yeah, that’s a hell of a different number than what the advocacy sites claim. There hasn’t been a single wind power plant that managed full-time production the way they assume, ever–Most of those wind farms in Hawaii and California that were built back in the last “wind power boom” never produced anywhere near what they were rated for, and the actual numbers for what they produced were horrendously bad, in terms of energy recovery. A huge majority of them never “paid back” what they cost to build, in terms of energy–Which was all fossil fuels, and would have probably been more efficiently used to just generate the electricity those wind power farms were supposed to.

    You have to watch these assholes, carefully, and go back and dig into the actual numbers they used. A clear warning sign? When you dead end, like I did in all those sites you’ve thrown up, and can’t find the actual data.

    My acquaintance had all that data to back up his assertions, and it was all carefully researched and verified. None of the available public documents I’ve been able to get my hands on ever go to that depth of research, and the thing you should be noting with all these advocacy sites is that most of their “evidence” dead-ends into sources that basically just make unsupported assertions. You won’t find the actual lifetime energy production figures for those wind projects in Hawaii and California that are currently rotting away on the hills, because those are mysteriously “not available”, likely because if they were, the people doing those projects would be in jail for fraud.

    The fact is that without the government mandates and incentive programs, none of this crap would be economical, and wouldn’t be happening. That’s a huge clue to what is really going on, and the reality is that we’re going to be paying the bill in terms of pollution and other costs to build this “pollution-free” alternative energy infrastructure for a long time to come. Just the damage done to the environment for the rare earth extraction effort alone is enough to make you really wonder who is benefiting from this entire sham of a “movement”.

  9. Gaikokumaniakku says:

    “The problem with those sites you don’t seem to recognize is that they’re run by advocates.”

    The two links draw on the USA’s Department of Energy and one of the biggest academic research groups in Europe. They are not amateur hippies. They cite quite a few peer-reviewed journal articles. This is not to say that peer-reviewed journals are above reproach – a great deal of error and fraud slips by peer review.

  10. Kirk says:


    See, here’s the thing: If they don’t provide the underlying data and assumptions used…? I don’t care who the hell they are, or what their “credentials” are–No data, no credibility.

    The guy I’m talking about? His stuff was impeccable–You could go out and verify it, run his calcs, and then be confident that you were looking at valid work. The folks from those “prestigious” outfits you’re credulously taking as accurate…? Why aren’t they doing the same thing?

    It’s just like the climate data–They hide it, and refuse to release it, claiming it’s proprietary. Even though it was paid for with tax dollars, they won’t give it up for anyone to give a critical look at it. This should tell you something, and where I’ve been able to examine real-world datasets, the difference between what they’re asserting and what is recorded is laughable.

    Too many people just take these people at their word, and never question whatever bullshit they’re spouting. Look for the actual numbers they’re using, and then do your own math while verifying. If they dead-end in “proprietary research”…? Well, do the math anyway. They’ve just revealed a whole lot of what you need to assess their credibility.

  11. Gaikokumaniakku says:

    “If they don’t provide the underlying data and assumptions used…? I don’t care who the hell they are, or what their “credentials” are–No data, no credibility.”

    The linked sources did indeed provide their arguments and assumptions. The data was a little bit shallow, compared to what one might find in a journal with good “supplementary data” sections. From my perspective, you seem to be arguing from a false premise.

    I’m not sure whether you examined the evidence and arguments in detail. If you are not willing to accept peer-reviewed data from any kind of scholarly journal, I can’t do anything to argue my case.

    I’m not sure what sort of peer-reviewed journals you typically read to get data and calculations from. In my experience, few scientists publish all of their data in their articles. A typical example of scientific disclosure is the following:

    Specifically speaking, the total energy input, including the energy input of the module manufacturing and the energy input of balance of system (BOS) is 19.5548 x106
    MJ, while the annual energy output is calculated to be 8.328 x 106 MJ. Thus the energy payback time (EPBT) is 2.3 years, revealing the conclusion that the establishment of the solar power station would contribute to a clean usage for more than 27 years, given the assumption of a 30-year operation period.

    doi: 10.1016/j.egypro.2017.03.281

    Also, I note that one of the files I linked — the original is here — has a list of five peer-reviewed publications. However, the citations are old and you would probably prefer more current research.

    However, perhaps you are not willing to accept peer-reviewed journals as evidence. I’m not sure how much evidence I would have to submit. Also, the “no data, no credibility” argument also applies to the analyst from Boeing. Until I see his data and his calculations, I should not regard his argument as having any credibility.

  12. Kirk says:


    See, here’s the problem: I go to those links, and there are no source numbers at all, just the bare assertion. The paper your extract is linked to returns nothing but empty pages from Elsevier, so I can’t look at and verify the assumptions they make to attain those numbers.

    I’ve yet to been able to find anywhere that these “trustworthy” types make the basis for their assertions available and clear. Maybe I’m not looking hard enough, but if I can’t get into the weeds enough to find one or two of their sources, verify them independently, and then run the numbers myself to see if their calcs are correct…? Yeah; I’m assuming it’s voodoo science, not real work.

    The paper you cite may be perfectly valid. Problem is, I can’t tell–Elsevier returns crap to my at my computer. And, when you look at the folks doing the research, by name…? They’re all Chinese, and working for the Chinese PV industry or academia engaged in that trade. Independent and trustworthy…? Not.

    I’ll look for that hard drive, and try to find the spreadsheet he built. I vaguely remember that he had a website, or had published it on one–I want to say it was something like “Energy Skeptic”, or something. Might have been on something like Geocities or MySpace, too.

    My point does remain, though–If you can’t see the basic numbers, and they’ve made everything opaque to the reader/researcher, then that’s the moment you start to go “Yeah, sure… Whatever.”, and move on to someone who does. We had a salescreature out to the house a few years, trying to sell photovoltaic to us. The poor bastard had an Excel spreadsheet that his company gave him, and which he used to make his presentation on rates of return, and so forth. However, when you looked at the cell formulas and everything else in that spreadsheet, there were some really interesting issues, like the formulas assumed 24/7 sunlight, no seasonal differences in sun intensity, and on and on. The poor bastard left in tears, when I got done with him. And, while the advertised “ROI” was supposed to be something like 4 years, the one installation that I know he sold someone still hasn’t paid itself off after nearly six years, with about two-thirds of the installation cost yet to be recouped. And, the photovoltaics aren’t producing what they were rated to produce anymore, either. The owner had a tech out to look at his system, and the tech opined that his equipment was not going to meet its rated lifespan due to the performance drop.

    Original installation company is nowhere to be found, these days, BTW. That’s a real-world example, and one of the many reasons I am highly dubious of the whole “alternative energy” schema–People have wrapped the whole thing in this aura of sanctified, unquestioning virtue, and that’s another good warning sign that all ain’t as it seems. Wind power is another example–All you need to do is go wandering through all the abandoned sites, look at the now-useless equipment, and wonder at how odd it is that they’re no longer in use, once the subsidies that helped pay for them are over with. Most “alternative energy” schemes are not actually about energy, when you dig into them: It’s more like they’re mining the government budget. Do witness that Germany, for all of its vaunted Energiewende, has some of the highest electricity prices in Europe, and that they’re still importing power from countries like France and Czechoslovakia. If the “alternative” sources were so damn good, why is that? Shouldn’t the power be cheaper than conventional, on the macro scale? Why aren’t the subsidies resulting in cheaper power for industry and the public?

  13. Gaikokumaniakku says:

    Kirk, you raise good points.

    Most importantly, the scientists presenting data often do have conflicts of interest with solar panel manufacturers!

    But let me focus on getting you as much data as possible. For starters, I hosted one of the relevant files at:

    I hope that you can download that PDF successfully and I hope it motivates you to keep fact-checking. Science definitely requires skeptical fact-checking!

  14. Kirk says:


    Have a look at Table 2 in that paper, “The life cycle energy requirement summary”.

    The area I question, and term “unsupported” would be all the numbers in that entire table. What are they considering as being a part of something like “Frame”? Is that the entire support structure, including the concrete used in the foundation supports? Without a breakdown of what they’re including in those areas for that entire table, it’s bloody opaque. You put in a major PV installation, you’re going to be using significant amounts of concrete: What were the energy inputs to calcinate the lime? Haul the gravel for aggregate? All of that stuff has to be included, or you’ve done an inaccurate and dishonest job of calculating the net energy costs. Most of these papers and “researches” dead-end in things like this, where they don’t show their work–Which is where I really start to get suspicious about the quality of it all.

    Not to mention, with this specific paper: What are the odds that the numbers in Table 2 would be so… neat and rounded off? The values in honest real-world calculations I’ve seen done on this are nearly always things like “337.58″, not conveniently even values like “400″, “500″, and so forth. That neatness of figure really makes me want to see the basis, because while I can buy one factor coming out an even “550″, the fact that the rest of the ones in that table are things like “400″, “100″, and so forth really makes me question the validity of it all. And, it’s not like we haven’t seen a huge problem with Chinese science being reproducible, or accurate, either.

    With due respect, and I do thank you for taking the time, I can’t look at this paper and say “Yeah, my mind is changed…”. If anything, the flavor of this particular paper makes my skeptic’s bump swell even more…

  15. Gaikokumaniakku says:


    I think you have an excellent, scientific mindset. I am giving you this info not so much to change your mind; rather, I am learning from your real-world experience. Your criticisms of past experiences (such as your debunking of the solar scammer) and present thoughts (such as your criticisms of the paper) can improve my future projects. Your skepticism is showing me the points that need clarification!

    You wrote:

    “What are they considering as being a part of something like “Frame”? … Without a breakdown of what they’re including in those areas for that entire table, it’s bloody opaque. … Most of these papers and “researches” dead-end in things like this, where they don’t show their work…

    Not to mention, with this specific paper: What are the odds that the numbers in Table 2 would be so… neat and rounded off? ”

    In the case of this particular paper, the authors explained that they are making an estimate that seemed reasonable for their situation. They cited Alsema’s paper as [16] as follows:

    Another factor is the transportation process, and assumptions have been made that the unit energy requirement for this was estimated to be 2-5 MJ/t/km, the average weight per m2 of panel is 15kg [16], and the average transportation distance would be 300km in China.

    It is reasonable to object to their estimation process. It is reasonable to also object to Alsema’s paper, which they assumed must be true.

    So there’s some bad news and some good news. The bad news is, right now, I can only give you the papers that are easy to access, and they are of comparable quality to this Chinese paper. They are not going to impress you!

    The good news is, now that I understand where you’re coming from a little bit better, I can find retrospective studies that provide a lot of accounting details. These are studies where someone went ahead and made the investment, then afterward published how much it cost and where the cost overruns occurred. That won’t be a complete answer, but I think it would address your criticisms better than this latest paper did.

    Thank you for your feedback. Skepticism is very healthy and beneficial for science!

  16. Kirk says:


    I appreciate your efforts. It’s rare to find folks on either side of the debate with minds that are still open enough to entertain the potential that they might be either in error, or been given bad information.

    The other area that needs to be addressed with these studies is the power production. You can’t simply go off of what the projected rating is, because inefficiencies creep in with regards to project-internal wiring, weather, and maintenance. PV is really vulnerable to this, because even a minor difference in efficiency of the cells can have major impact across entire installations, drastically changing the numbers which were projected.

    One thing we’re all really bad about, across human engineering and design efforts, is that we don’t go back and look at how things actually did after we build them. I can only think of one auto manufacturer that made a habit of monitoring their vehicles out in the field after they were sold, and that was Saab. They had a program where they’d sell a car at a reduced price to a long-time customer, and then every so often, take it back in for a full analysis to see what parts were wearing, and why. This information was fed back into manufacturing, and created a much better feedback loop to the design team. It is unfortunate that more manufacturers don’t do similar things, especially in the construction industry. I know for a fact that we find stuff in remodeling and insurance work that was done in accordance with manufacturer’s installation instructions, and which simply has not worked out in terms of weatherproofing or structural strength. I think that a huge missing piece of our engineering process is that we need to start going back and looking at things we’ve already built, and then carefully analyze how that structure or piece of equipment worked out, in service. Even the military is horrible at this–I used to do a lot with small arms, and what struck me the most was all the lost opportunities we had to find out just how our equipment was working, in the field. They should have been doing longitudinal testing of equipment sets, baselining them in terms of wear and breakage, before deployment, tracking how much use they were actually seeing downrange, and then taking them in after the fact to evaluate the condition after deployment, in order to assess the effectiveness of lubrication, coatings, and overall design/materials.

    Similar analysis needs to be done in about every field of endeavor. You can project all you like from lab testing, but until you’ve got that PV installation out in the middle of the Mojave or Gobi deserts, in service, you just don’t know how it’s going to work out, or what the actual numbers are going to be.

  17. Alistair says:


    Agree about solar PV audit of input. It’s frustratingly difficult to get properly sourced calculations for PV and Wind EROEI and ROI; but it shouldn’t be hard to do! So yes, the lack of good, well detailed breakdowns in many “sources” is itself suspicious.

    As far as output goes, I can only nod my head in agreement about real world degradation issues. I have a lot less experience in PV, but have a reasonable amount of experience in wind. Here, a typical factor of real world degradation is about ~30% down from the modelled baseplate at a specific site with 5-minute wind data. There was a good paper on this (which I might be able to dig) which came out with a 0.29 estimate which I got similar numbers to from multiple regressions on actual output of all the major wind farms in Scotland for the last 12 years.

    It has to be said, one of the biggest sources of degradation is clearly due to number of turbines in field, and wake effects (something like 20% rating loss per 10x scaling). This is very unfortunate for anyone wanting a civilisation scale rollout of this tech; it has strong negative returns to scale.

  18. Kirk says:


    You put your finger on the primary reason I have such a deep cynicism on this issue. Couple the dearth of actual clear and reliable data with the rent-seeking behavior of the majority of the players in this field, and you really start to question their motives. There have been huge fortunes made, and a few lost on the side of the legacy industries, another set of facts I find troubling…

  19. Gaikokumaniakku says:

    A lot of the reasoning in the links I cited seems to trace back to the following:

    This seems like a very brief sketch, but it is a spreadsheet with calculations. I fear these calculations won’t be convincing, but this is a key link in the various estimates. This spreadsheet comes from ECN.

    I don’t believe the spreadsheet is expected to stand on its own; it appears to have supporting documents somewhere to explain it, but I need to find those docs.

  20. coyote says:

    Gentlemen: thanks for the gentlemanly discussion of this issue. If I may address the vulture of critique (only, sir (and I apologize), due to my inability to pronounce your name: There are very lengthy and scientific discussions of the alternate energy technologies at Anthony Watts site “Watts up with that”- those who “outed” the CO2 global warming affair. As noted above, follow the money to see who benefits from these scams. The environmental disasters in China mining the rare earth minerals, the degradation of our western landscapes (with “special exemptions” to kill bald eagles), the bribes and payoffs to contractors, – on and on. The only thing these technologies are good for is for individual homes who can build in backup and can afford the future maintenance. Most are looking at 15-20 yr paybacks; and wrapping into a low-interest mortgage made sense for some.
    Thanks again for your interesting commentary.

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