Elon Musk says he's planning a 'supersonic, electric hover jetplane' Hecamillionaire space cowboy Elon Musk has revealed new and ambitious plans for the future - among them the idea of a "supersonic electric jet" able to make hovering landings and takeoffs. The one-time PayPal luminary and founder of both upstart rocket biz SpaceX and electrocar darling Tesla Motors is also pondering plans to …
To me it sounds frankly impossible. There is no way to develop enough power from any battery for more than a few seconds of supersonic flight. As a builder of electric model aeroplanes I am fully familiar with the limitations of that technology. Also if some other power source is used to generate electricity, the question as to why that power source is not directly utilised has to be asked.
In short its just a load of fluff and bollox. It may sound sexy, but it wont work.
But then these days not a day passes without the announcement of some new technology that ticks all the boxes in the dreamlist, but none in the list of things that include economically viable and physically possible.
I myself have patented the idea of a green car that runs on wish fulfilment alone. And we shortly be applying for a billion pound grant to develop it.
@itzman
That was a seriously funny post. I have visions of itzman rocking up to Mr Musk waving about his 10'' electric R/C plane and explaining why Elon is plain wrong. And plane wrong.
Also, you need to spend less time building said R/C planes and practice hitting the apostrophe button instead.
Here you go: "It's just you" and "...won't work" (I know there's a second "its" error)
And while I'm at it, "dreamlist" and "I myself" aren't really English either.
To you and other doubters here, I would wager that the man who founded and runs Spacex, a company that that has made multiple successful spacecraft launches to low earth orbit *might* be better placed than yourselves to decide whether it will or will not work.
Call me crazy but I think he'd have considered the enginnering challenges before going to the press.
Let's wait for more details shall we, hmm?
I'm sure your experience with model planes gives you far more insight into cutting edge technology research than a man who owns two tech research companies and has successfully designed built and launched space rockets.
I know exactly how you feel, too - I had an RC car when I was a kid and now I'm fully qualified to tell Lewis Hamilton how to drive. Sadly, he won't return my phone calls, the fool.
Nonsense. Not only is this idea feasible, but it is very sensible. You're getting hung up on the word electric. It is quite obvious, however, that it really is impossible to have a viable plug-in electric plane. Has it occurred to you to ask why would Elon mention something as stupid as that?
If I had to venture a guess. The plane doesn't store fuel as electricity, but rather as liquid hydrogen. The 'electrical' label is there to prevent it from being shut down by the Hindenburg crowd. Liquid hydrogen is 5 times more energy dense than kerosene, so the plane would be significantly lighter. It can also achieve much higher peak power very easily, allowing for hover and supersonic. Both of those are crucial for economic viability of the craft. Airline companies aren't going to take a gamble on a new technology (especially hydrogen) unless in addition to slight fuel savings, it offers unprecedented capability.
So, how many hydrogen fuel cell model airplanes have you built?
Oh, and as to why a hydrogen fuel cell plane would be called electric - for all intents and purposes it essentially is. The turbines will be electric and hydrogen can be electrolysed wherever there's water and electricity. It's merely used for more efficient (by weight) energy storage.
Metal hydrides have much higher storage densities without all the hassles associated with very cold and/or high pressure hydrogen gas.
See http://www.dalefield.com/slspartners/hydrogen_fm.html
Myth 4 – Hydrogen has a higher energy density than gasoline or diesel
Hydrogen has more energy per unit mass than other fuels (61,100 BTUs per pound versus 20,900 BTUs per pound of gasoline). The problem with hydrogen is that it is much less dense (pounds per gallon) than other fuels. A gallon of gasoline has a mass of 6.0 pounds, the same gallon of liquid hydrogen only has a mass of 0.567 pounds or only 9.45% of the mass of gasoline. Therefore one gallon of gasoline yields 125,400 BTUs of energy while a gallon of liquid hydrogen yields only 34,643 BTUs or 27.6% of the energy in a gallon of gasoline. The Space Shuttle uses hydrogen as a fuel, because its mass is low, and the fuel is carried in an external fuel tank that is jettisoned during lift off. Automobiles can not have external fuel tanks that are discarded, and the energy per unit volume is used to determine a fuel’s energy density in automobiles. Compressed gaseous hydrogen is even less dense than liquid hydrogen. At 5,000 psi of pressure gaseous hydrogen only has a density of 0.25 pounds per gallon or one twenty fourth the density of gasoline. Gasoline and diesel are far superior fuels to hydrogen in this regard.
Liquid hydrogen does indeed have a higher specific energy than kerosene. However, when you take into account the cryogenic containment system you need, things don't look so rosy. Additionally, liquid hydrogen is about 1/10 the density of kerosene, so you need a lot more volume to store the same energy.
"As a builder of electric model aeroplanes I am fully familiar with the limitations of that technology"
I respect that.
"Elon Musk is an engineer and entrepreneur who builds and operates companies to solve environmental, social and economic challenges. He co-founded PayPal and currently drives strategy, development and design at two companies he created, Space Exploration Technologies (SpaceX) and Tesla Motors, and oversees a third company, SolarCity, which he co-founded. He led SpaceX’s efforts to be the first private company to successfully launch and dock a spacecraft with the international space station" (http://elonmusk.com/)
And I also respect that.
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Just what the heck is an electric jet?
Does he mean a plasma or ion thruster?
Is he even aware these things actually exist.. but are only used in space because.. well that's the only place they really work..
He should stop squandering his money on silly things like overweight 'sports' cars only capable of hatchback speeds and instead pay me to make a proper sports car.
Isn't "electric jet" a bit of a contradiction in terms? Call me a nitpicker, but a jet engine to me generally involves burning fuel, and a plane described as a jet is generally powered by the aforementioned fuel-burning jet engines. Still, I like the sound of it, whatever it's called.
+1
weight of ..... turbine, & motor & battery(or fuelcell+tank)
Good luck getting enough power-to-weight, and figuring out how to get your turbines to survive supersonic intake
-OK you could try variable inlet spikes....
My advice .. if you must do it, limited liability company, no hyping, and stay away from Moller :P
> "but a jet engine to me generally involves burning fuel"
Generally yes, but alternatives have been proposed - e.g. a nuclear reactor for project pluto (http://en.wikipedia.org/wiki/Project_Pluto). As a completly wild guess he could be talking about using a similar ramjet design but with a really big electric heater instead of the nuclear pile.
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If you do a bit of research you'll find that Boeing and Airbus have active research projects into electric commercial airliners. Use a conventional turbine running at a constant, efficient, speed to generate electricity to charge batteries. Call on the batteries for peak energy needs, i.e., when taking off.
The supersonic part I'm a bit fuzzy on, but I'm not sure I'd bet against Musk's record.
It's usually called a "more electric aircraft" and it's electricity for replacing the *hydraulic* systems on board with electric actuation, eliminating *lots* of high pressure (c 4000 psi) tubing, issues with leaks, issues with it absorbing water, aid bubbles etc.
Front runners for the generator system are miniature un-lubricated gas turbine systems with direct coupled generators and fuel cell systems.
No one is planning on replacing the high bypass gas turbines hanging under the wings *anytime* soon.
Why are you people talking about an electric turbine as if a turbine is something that can be driven by electricity? That makes no sense at all! A turbine converts fluid flow into mechanical energy and occasionally thence into electrical energy, going the other way you do not have a turbine but a compressor or pump.
Fuck me.
Torn between the nuke icon or ironic use of the "degree level" icon... or the pint because it's enough to drive a man to drink.
It's called a "Sense of humor"
And he's quite adept at thinking on his feet when using it. Anyone remember the question about being a Bond villain and his quip that "I don't have any collarless jackets in my wardrobe"?
He may also be aware of the story of HH sinking a *lot* of money (for the time) into a SoA steam powered car. Logically quite reasonable (team found a way to solve most problems after a fashion) but practically completely bonkers.
I suspect this is more of a ribbing than a serious idea and (as a graduate physicist) he'd know just how *much* energy such a machine would need.
There is a reason why you cannot buy a high *thrust* ion drive for rockets.
He didn't say all-electric, he said electric. i.e
superconductor fan <------> motor controller <------> capacitor <-------> generator.
There are enormous efficiencies to be gained from mechanically decoupling the fan from the compressor and turbine and spinning each at the most optimal speed. The reason why it hasn't happened is because airlines and manufacturers are even more risk averse than car companies. They're even choking on geared turbofans, and they've been on the drawing boards for decades.
He's investing his money and creating jobs (and the future) by starting SpaceX, Tesla and perhaps this VTVL electric superjet company. Unfortunately there are too many millionaires who just give their cash to hedge fund managers to speculate on currency and commodity futures, which only creates jobs for hedge fund managers.
Too bad there aren't more of the former than the latter, then we wouldn't still be talking about how crappy this economy is.
While the story of the self-made millionaire is a popular & oft-repeated one, the truth is, most of today's millionaires inherited their wealth.
As the saying goes, making a million out of nothing, that's hard. Making two million out of one million, that's inevitable.
When you make your first million, you're keenly aware of the people/systems/networks around you that enabled you to make that million so you're more likely to invest in those people/systems/networks etc. When you get handed your first million, you're less likely to make that investment and more likely to let it turn itself into two million while you jet around living the high life.
Flying car? Doable, but not in the next ten years without a lot of money thrown at it and you'd still have big concerns about safety. A car going off the road at 40 to 60 mph is one thing but a car falling out of the sky at 100 to 160 mph? Even if the flying bit worked, the debate over control systems & safety would take years.
Electric car? Doable, (in fact, it's being done) but it won't replace regular cars until the price comes down, the battery life goes up and the recharge time gets down to 10 minutes or less for a daytime top-up.
An electric jet? I have no idea what that is. An electric propellor engine now...
A supersonic, electric jet that can do vertical takeoffs & landings? Yeah, we'll have those just after we get unicorns to ride.
I have to say, I really admire Elon Musk. I always like to think if I had his wealth I would probably do more or less the same (yeah, in reality I'd blow it all in Las Vegas or something).
I wish he would invest in Reaction Engines. The Skylon seems like something SpaceX could really use/develop.
Quote
I wish he would invest in Reaction Engines. The Skylon seems like something SpaceX could really use/develop.
Unquote
I wish he WOULD. They'll need up to 10 billion dollars over the next ten years. That said, REL will never co-operate with SpaceX (an American company) because if they did, ITARS would kick in, all the REL Skylon technology would become American & REL would have to lease their own technology back from SpaceX.
So he could buy shares and get dividends but that's about as far as it could go. REL is likely to licence construction to EADS (Airbus) or British Aerospace, keeping only the Frost Control technology & precoolers for themselves.
According to Mark Hempsell (of Reaction Engines) US citizens (I'm fairly sure Musk is one now) risk *arrest* under the ITAR rules as they are funding a (potentially) military technology.
And courtesy of shrub *all* space technology is viewed in that way, not just solid fuel, reentry nosecones or space nuclear engineering.
Musk is not putting on an Orange jumpsuit anytime soon.
A friend of mine has bought one, and plans to drive it north to visit me soon. Hmm. Let's see. Maximum range is claimed to be about 220 miles, so at motorway speeds it's probably safe to assume about 175 miles. A one-hour charge restores 80% of battery capacity, so he'll be fine if he stops for an hour every 140 miles or so. Giving an average speed of (140 miles) / (2 hours driving + 1 hour charging) = 47mph. Whoop de do. That's a hundred grand well spent.
Said before, will say again... you want a proper eco car which will also appeal to er.. 'motoring enthusiasts'? Gimme the moneys (all of them). To be fair the Tesla was ahead of it's time, by a little bit, wasn't it? I mean now Nissan, Ford, Renault and uh.. some other guys, offer fully electric cars. How good they are and whether they become easily and expensively bricked or burst into flame is tbc. Really Mr. Musk should contact some proper automotive engineers for umm.. joint ventures. *cough*hint*cough*
electric jet....
what does he mean?
"jet" like "scanner" is a word with *many* possible meanings. They refer to a *result*, not a cause.
"Ion engines" for example, produce a jet as well, but it's not a gas turbine, which is probably what most people are talking about.
For something more direct NASA did look at a *direct* electric thruster. This took GH2 and fed it to a 30Kw tungsten filament heating element (yes it's basically a giant light bulb element). IIRC it was part of their nuclear rocket engine work for attitude control and had a thrust of < 100lb.
You'll need a bit more thrust to get vertical takeoff.
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