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Currently watching Felix on What About It; working towards a flight of SN-11.

For electric aircraft supporters ...

Today's news feed included an item about a design for an electric powered aircraft system using a hybrid approach ...

A passenger vehicle is designed to fly 300 miles at 200 miles an hour, with (I ** think **) six passengers.

The system would feature a drone to lift the passenger plane from a small inner-city port, carry it to altitude, and release it to fly to the destination.

At the destination, a similar drone would capture the aircraft and land it gently in vertical flight mode to a similar small landing field.

At this point (I got the impression) the system is purely conceptual, but I liked the concept.

The capture of link and text got lost along the way, but (hopefully) other forum members will be able to find it.

(th)

"Plan and prepare for every possibility and you will never act.  It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing.  Great things are accomplished by embracing great dangers" - Admiral Sauvitaire (addressing a class at the Martian Naval Academy).

It is an excellent quote, but the history of engineering has shown it to be foolhardy.  Whilst caution and meticulous analysis of risks may be expensive, and adventurous men may grow impatient at delay, an accident is often catastrophic.  It is wiser to proceed with caution and arrive a little later, than to stumble into a catastrophe that may end the programme.

More troubling should be the one's that get the virus after having the 2 shots of vaccine.

Louis: 

I looked at the article whose link you provided.  What it says and what you claimed it says are the exact opposite.  It says polio outbreaks happen where vaccination rates are low.  And did you notice that the US is NOT on the list where outbreaks happen?  There is a reason for that:  vaccinations.

I was born during the last polio epidemic in the US.  The vaccine was not available until I was in the second grade,  and it was the Salk injection,  not the Sabin sugar cube (that came 3 years later).  I was lucky,  but my cousin and some friends were not.  They got infected before the vaccine became available.

You often make good sense and say good things,  but your anti-vaccine denial BS is NOT part of that.

GW

Reading the link showed we do not have a natural immunity to the polio but require the vaccine to help the body against it as it did not give it to them.

Current US variants not including the first two are now 3 more from the UK, Brazil and Africa. These are being tested in labs to see if the vaccines work on them as well.

louis wrote:

Totally unconstitutional and unethical that your employer should be able to force you to take a medicine which could kill you.

SpaceNut wrote:

Got moderna shot today at work as required and aside from sore arm at shot site the only other thing is a headache which is a side effect for some.

Employers can and do make many rules to stay employed and this is just another of them which include mask mandates.
Plus if I were to die they pay forever in one way or another in insurance payouts to family.

Got moderna shot today at work as required and aside from sore arm at shot site the only other thing is a headache which is a side effect for some.

For Calliban re #76

Louis is an important contributor to the forum, in the sense that he is able to draw forth outstanding and memorable posts by those who ARE knowledgeable!

This has been going on for years!  If you ever have time (which I understand you don't) you'd find numerous instances of Louis leading knowledgeable members to creation of remarkable posts.  The challenge for the rest of us (who might want to be able to find those memorable posts again) is that the forum structure does not lend itself to retrieval of such worthwhile posts.

That is why I try to set up little trail markers from time to time, but even those suffer from limitations because it is so difficult (for me at least) to think of short tags that others might find helpful.

So I disagree that your posts are a waste of time.  As you create them (if you ever decide to do so again) please keep in mind that Louis himself is not (or ever could be) the target of your work.  You are (hopefully) writing for those who visit this forum without ever becoming members, and for some registered members who are following the major contributors closely.

Just look upon Louis as a sparring partner who gives you a framework for some of your best thinking.

(th)

Louis,

louis wrote:

kbd

I think this article answers some of the points you make:

https://www.theguardian.com/world/2020/ … rst-flight

The real attraction for operators will be the lower running costs of electric aeroplanes - maybe 40-70% lower according to the article, which sounds about right to me.

I've already read that article.  You keep talking about a fanciful concept that simply doesn't exist.  It doesn't matter all that much that the batteries cost less to recharge if the aircraft in question is so much larger and heavier, therefore more expensive to own and operate, that nobody can afford to buy and operate it.  Even if they could, it still can't carry much of anything to pay to turn all those cheaper stored electrons into noise.  That article doesn't address any part of the physics of flight, which is what I was addressing.  Weight takes power to push through the air, and lots of it.  There are clever aerodynamics tweaks that you can use to minimize the total drag generated at a given design operating speed, thus the power that must be generated to remain airborne at that speed, but you cannot overcome the need to produce power to keep weight in the air.

Unlike car engines, the only time aircraft engines are idling is while sitting on the tarmac and just prior to landing.  At all other times, they're operating at a significant percentage of their maximum rated output. If you use a turbofan engine or motor driven fan, at 375mph, it's generating 1hp for every pound of thrust generated.  If it takes 375hp / 279.6kW to push the airframe to a given speed, then that's how much continuous power any kind of propulsion system must produce to continue moving at that speed.  At an energy density of 160Wh/kg at the battery pack level, that equates to a 1,748kg battery pack.

As an American, I work in pounds (just to tee of metric people, if for no other reason), so let's examine what that means from a practical electric propulsion system design perspective:

1,748kg = 3853lbs

A 550hp PT6A-21 gas turbine weighs 327lbs and will consume fuel at a rate of about 0.63lbs/hp/hr in cruise.  Subtracting out the weight of the engine, that leaves us with 3,526lbs of fuel to play with.

To produce that same 375hp that the battery can generate (and we're completely ignoring the weight of the electric motors here), we're burning around 236.25 pounds of fuel per hour, so that's just shy of 15 hours of fuel onboard!  I don't know about you, but I can't think of any practical airframe powered by a single 550hp PT-6A that carries that much fuel, apart from some of the airborne relay drones in Viet Nam that had no pilot or paying passengers or cargo onboard.  A Beech King Air C90 series that's powered by a pair of PT-6As has an empty weight of 6,950lbs and a maximum takeoff weight (MTOW) of 10,100 pounds, so all fuel / baggage / crew / passengers / fuzzy dice can come to a combined weight of 3,150 pounds.  That means the battery alone weighs more than the payload capacity of a fairly large light commercial aircraft.  There's also another problem we've yet to address.  The King Air needs two of those beautiful Pratt engines to cruise around at 250mph.

How many people do you know of who are looking for a $2M to $4M King Air that can stay airborne for a maximum of 30 minutes, bearing in mind that those things normally have a range of over 1,400 miles and can stay in the air for almost 6 hours?  If it's airborne for a half hour, then it can fly about 125 miles at most.  While there are a few flights that short, most flights in a King Air are a third of the way across the country, like Las Vegas to LA, for example.

Who do you think is going to pay for a multi-million dollar zero pilot / zero passenger / zero cargo aircraft that flies for 30 minutes?  World's most expensive privately owned RC toy?  How are you supposed to make money with an aircraft that can't carry anything but the battery it needs to get off the ground, because more than 100% of its available payload capacity is consumed by a boat anchor for a power source?  As light as Lithium-ion is, when compared to Lead-acid, it's an absolute brick for flying when compared to any gasoline or kerosene burner in existence.  Thus far science can't seem to "deliver the goods", with respect to a remarkably more energy dense battery.

As "fluffy" as liquid Hydrogen is for a given weight of the stuff, it still has sufficient energy density for real flight applications, especially if it's reacted in a fuel cell, as does liquid Methane and Propane.  A nuclear reactor can supply the enormous amount of continuous thermal and electrical energy required to synthesize those fuels.  A wind turbine or photovoltaic farm may be able to supply intermittent energy, but chemical plants aren't shut off because clouds are overhead, the wind isn't blowing, or day turns into night.

louis wrote:

Everything has to start somewhere - modern planes started with the Kitty Hawk.  The 9-seater looks viable for short island hopper flights.

Fair point, but normally you start with something that actually works.  The Wright Brothers didn't attempt to fly with a cast iron engine block, nor Lead-acid batteries, because they knew the power generated per unit weight carried aloft was insufficient with motor vehicle battery or combustion engine technology of the time.  They used Aluminum instead of cast iron by casting their own components.  That's the only reason that their bird left the ground.  Hydrogen fuel cells do actually work, and can even reduce the weight of the propulsion system carried aloft aboard a light aircraft, so a like-kind replacement is feasible without invoking technology that doesn't exist.

louis wrote:

I don't think you understand the relative significance of EROI or how it relates to green energy.

Concepts like EROEI aren't independent of all other considerations.  The EROEI of nuclear fusion could be absolutely stellar (you can decide for yourself if the pun was intended), but we simply don't know because we can't make one that produces more power than it consumes.

louis wrote:

Try this thought experiment. You are a clever engineer who creates a magnificent set of algorithms which allows solar powered robots to function in the asteroid belt, mining materials, refining raw materials, constructing factories and making things. These robots are so clever they can even build rockets. Now, you being so clever have built into these robots' algorithms that they will always want to serve you and bring you finished products at no charge. The robots built a nice rocket landing pad near your home and periodically bring you lovely products entirely free of any charge.

People who are way more intelligent than I'll ever be haven't yet built a robot that can perform the simplest of tasks in a completely autonomous manner, so the rest of the thought experiment is moot.  Thought experiments are also reserved for academics at universities and Hollyweird screenplay writers, not clever engineers.

louis wrote:

Now, it is clear these robots are using huge amounts of energy to operate in the asteroid belt and make the products they do. But it is equally clear from this experiment that they have no reason to levy any sort of charge, despite the prodigious amounts of energy being used.

Yes, if they're creating the machines that produce the energy they consume, then up to some incredibly large figure limited by raw materials, they can consume energy like it's going out of style.

louis wrote:

What really creates the need for price is human labour input. It isn't the fact you use x KwHs in making a product that determines its price, it is that in order to use x KWhs, z number of people are employed in helping get that energy to a point where it can be used in the making of the product. This applies though only where people are free because free people will not work without reward. If we look at slave labour, again there is no need to generate price. On a Roman villa farm lots of activities would take place and products would be made - all involving slave labour - but at no cost to the slave and land owner. Same on slave plantations in the past in the Americas. Yes, the slave needs to be fed and otherwise minimally maintained, but that is like the energy used by the robots.

We've already established that a robot can't walk into a room, or float in the water, and marry up two randomly shaped pieces of sheet metal to weld together without a LOT of assistance from sensors that humans design and tweak, ultimately prodigious quantities of skilled human labor, because if the robot could actually do that, then our factories would be devoid of people.  Similarly, none of the robots have the ability to repair their own circuitry without human labor.  So putting a bunch of robots out in the asteroid belt STILL requires a ton of human labor, many millions of miles from home.

louis wrote:

Your point about energy budgets for activities is of course a truism. If an activity is not generating energy, then it cannot continue indefinitely without additional energy inputs.

Yes, human powers of basic reasoning and the use of relatively simple, if intricate, logic exists for very fundamental reasons.  It's utterly necessary to orient yourself in the world and to interact with it and other people in ways that are, minimally, merely survivable.  I'm not any kind of philosopher, though.  I recognize my own limitations, in that regard.  I lack that kind of creativity.  What I do know how to do is to interact with and manipulate rules-based systems to get the end result that I'm after, so long as I know what the rules are.  That's the basis for sound engineering work, BTW.

louis wrote:

The error I think you fall into is assuming that EROI is the key factor to energy budgetting, It isn't. The key factor is relative ubiquity. The point  about energy resources like wind, solar and geothermal is they are pretty much ubiquitous across the planet. To take solar, the energy from the sun transported to the planet is huge, enough in one hour to power humanity's needs for decades. More than that, it is readily available all around us, not concentrated in a few locations. So even if solar let's say had an EROI of only 5% of coal's EROI, if we have the right technology - meaning in effect the right price - we can easily build up a larger energy surplus from solar than from coal. So while it's true - in this case - that for every 1 energy unit put into coal I get 100 and I only get 5 from solar, solar is all around and easily available to use if you have the right technology whereas coal is unevenly distributed and its extraction involves mature technologies that are not going to deliver major cost reductions. With solar you have a scenario where you can just invest the 1/4 of your energy surplus back into solar and you can continue to grow your energy surplus at a prodigious rate. With coal, if you did that you would soon strip all the more easily accessible coal deposits.  But with solar we can go on and on, and if we get the technology right we can exploit solar power beyond the narrow confines of Earth e.g. with solar power satellites.

Uranium and Thorium are also ubiquitous.  They're present in every gallon of sea water, just like the Lithium used in Lithium-ion batteries.  That doesn't mean it's easy to extract or that the extraction is "free" in terms of energy consumption, merely because the energy resource is ubiquitous.  Otherwise, we wouldn't go to South America to extract Lithium when we can start filtering it out of sea water.

The mere fact that sunlight and wind are present across the entire planet doesn't make them an intrinsically useful resources, because those resources are very diffuse and require an enormous number of enormous machines that require enormous quantities of materials, therefore enormous quantities of energy to fabricate and maintain.  The total quantity of energy delivered by the Sun is only usable if the entire planet or some very healthy portion of it was covered in solar panels or wind turbines, or there are international power grids established to move electricity around the world.

You can't make those machines cheaply enough to overcome the fact that they require 10 times to 100 times more materials to produce equivalent quantities of energy output.  We use concrete, steel, light metal alloys, and composites for everything.  We don't use Uranium or Thorium for any other purposes apart from fissioning them in nuclear reactors, so your repeated attempt to conflate steel and concrete production with fissile material production is a bad comparison.

Thus far, our "energy surplus" from solar is at or very near to zero, precisely because the most practical / cheapest storage mechanisms, molten salt or molten metal, are not being exploited batteries.  There's enough fissionable nuclear materials sitting in Paducah, Kentucky to supply 100% of the US electricity needs for the next century, or next three centuries if we have a more appropriate mix of power generation technologies.  The storage mechanism for wind and solar cannot begin to "store" the electrical energy used by the entire United States, for at least the next century, in a physical space smaller than a football stadium.  It doesn't matter how "ubiquitous" you think Uranium and Thorium should be, either.  They're a technological fact and the quantity of fissionable material in Paducah is a physical objective fact, not subject to anyone's ideology.

With appropriate storage and energy surpluses, we can continue using wind and solar into perpetuity.  Without a fully functional storage mechanism, we cannot.  People advocating for using wind and solar for everything need to first demonstrate a 16GWh storage facility that can supply 1GW over the 16 hours of the day where there is no sunshine or wind.  A power plant is only a power plant when it generates power.  I don't care if the power is generated or stored for later use, but power needs to be available to cover demand at all times.  Nuclear easily accomplishes that, without spending a dime on storage, or having two or three different power plants to account for the highly variable output of wind and sunlight.