Boeing Working on Fuel Cell Aircraft

"Boeing is working with development partners on a fuel cell-based small aircraft. It seems like a logical use of the technology. Now if they can come up with a quiet, personal-sized VTOL craft a la Paul Moller's Skycar (which is anything but quiet), we'll really have something." From the article "A Boeing research director was quoted as saying, "While Boeing does not envision that fuel cells will provide primary power for future commercial passenger airplanes, demonstrations like this help pave the way for potentially using this technology in small manned and unmanned air vehicles."

Comments

Better hurry up...

[kmac06]

I want my flying car by 2015.

Re:Better hurry up...

[$RANDOMLUSER]

I realized that Popular Science had been lying to me about flying cars when the diesel powered typewriter they predicted never materialized.

Re:Better hurry up...

[El Torico]

I have horrible visions of the skies over Naples, Italy if that happens.

Re:Better hurry up...

[kmac06]

Hook up a diesel-powered UPS to a computer!

Re:Better hurry up...

[peragrin]

I have horrible visions of a 2000 car flying pile up.

Re:Better hurry up...

[GFree]

I'm sure in 2015 plutonium is available at every corner drugstore, but in 2007 it's a little hard to come by.

Re:Better hurry up...

[Anonymous Coward]

Air routes have a way of being "self-cleaning" unlike a freeway. You collide with another plane, and you won't be in the way of traffic for much longer. The most damage you could have is maybe 2-4 flying vehicles, and some unlucky building on the ground. That said, the psychological impact on the public of a collision between two flying vehicles would far exceed that of a 2000 car pileup.

Re:Better hurry up...

[Solra Bizna]

the psychological impact on the public of a collision between two flying vehicles would far exceed that of a 2000 car pileup.

Not to mention the physical impact. (How likely am I to survive crashing into another car and then falling 60 or more meters to the ground?)

-:sigma.SB

Re:Better hurry up...

[joto]

On a scale from 1 to 10?

1

Skycar

[Anonymous Coward]

The Skycar is vaporware. It has been for the last 30 years. Please don't use the Skycar as a benchmark for anything but hype and failure.

Re:Skycar

[Anonymous Coward]

Amen! I remember reading about the Skycar in "Popular Mechanics" in the library way back in middle school... WAAAAY back. Let's not pretend any longer that we'll all one day be flying about in our own personal jets. Most people have enough trouble controlling a vehicle with two degrees of freedom. There's a very good reason why getting a pilot's license is much harder and more costly than getting a driver's license.

Re:Skycar

[kmac06]

Of course not everyone should be allowed to pilot/drive a flying car. But that doesn't mean there will never be a cheap (~$30,000) flying car/plane that will require a pilot's license to operate.

Re:Skycar

[WED Fan]

Have you ever noticed that you never see David Copperfield in the same place as the creator of the Moller Skycar?

The guy is either one of the most deluded inventors, financially incompetent, or a huckster. Or, all of the above.

Re:Skycar

[Anonymous Coward]

You can already buy a Cessna C172 for $30,000. They might be older but they still fly. What is really needed is airplanes which require lower maintenance fees and I don't think you'll get that by stuffing ever more expensive tech into them.

Re:Skycar

[YrWrstNtmr]

What is really needed is airplanes which require lower maintenance fees

A&P certified mechanics are expensive.

Re:Skycar

[QuantumG]

No, what's needed is vertical take off and landing vehicles for that price which don't make insane amounts of noise or vent extremely hot gases in a way that is dangerous to third parties. Without that, you can't replace a car with a plane, assuming that's what you want.. I know it's what I want.

Re:Skycar

[YrWrstNtmr]

No, what's needed is vertical take off and landing vehicles for that price which don't make insane amounts of noise or vent extremely hot gases in a way that is dangerous to third parties.

And to do that we just need to suspend the laws of physics. Unless you know of another way of lifting 2,000 lbs straight up in the air.

Re:Skycar

[zippthorne]

Yes, but one reason is Moller's sticking to a flawed plan IMO. He states that he wants *everyone* to be able to have one, and he makes the appropriate design choice for that goal, but it's not an appropriate choice for a product that will be sold within even 10 years. He wants the plane to fly itself. (He also requires what amounts to a complete revamp of the ATC system, but NASA and others are already researching something similar to his needs in that arena)

As long as that's a requirement, the plane will never be ready. If he's willing to sell it as a toy for rich playboys with nothing better to do, it might one day take off, (heck, even if I had the money, I wouldn't buy the Fischer Price version anyway), but it doesn't look like he'll take the pragmatic route.

Re:Skycar

[MobyDisk]

You can buy a Used Cessna for well under $30,000 US dollars. Up your price to $40,000 and there are a lot more. A Hummer H3 runs between $30,000 and $40,000.

Re:Skycar

[maxume]

It's important to point out that you have never seen me in the same place as David Copperfield either.

Re:Skycar

[onescomplement]

If I were their director of marketing:

"The Skycar remains perfectly positioned for the expected invention of antigravity."

Re:Skycar

[QuantumG]

Unless you know of another way of lifting 2,000 lbs straight up in the air. Step 1: ask the 3 american passengers to hop out.

Re:Skycar

[nothing now]

heyy... we're not all fat!
  I'll have you know I only wheigh 250 lbs or 113.4 kg and I'm 6ft 1 inch or 1.85 meters abouts.
so sod off! , only lazy suburbanites and welfare families are that fat.

Re:Skycar

[Anonymous Coward]

Are you implying that you invented the Moller Skycar?

Re:Skycar

[QuantumG]

Unnecessarily tall. :)

Re:Skycar

[geobeck]

Step 1: ask the 3 american passengers to hop out.

Conveniently enough, that will also take care of much of the noise and venting of hot gases.

:

Re:Skycar

[shmlco]

"As long as that's a requirement, the plane will never be ready."

Never be ready? I've been following the thing with interest for years, and as far as I know no one's ever seen the thing fly at all. Computerized or not.

Re:Skycar

[zippthorne]

He claims tethered flight of the M200, (or an alleged M400 that looks suspiciously like a M200 to me...)

I don't know about the concept: a flying wing four feet wide, eight feet long, and only 400 mph seems a bit ambitious to me, but if the math supports it...

Though working model in hover mode seems more plausible to me.

I did not mean to imply that it was finished except for the control system. Although it does seem to me that the control system is significantly holding it back.

Re:Skycar

[Anonymous Coward]

OK, I know this is probably a joke (sod off? Who the fuck in the US says that?), but 6'1 250lbs is a fat fucking fuck. I'm 6'4, if I weighed 250 I would cry every day of the week. It's a BMI of 33, which is pretty firmly in the "obese" category.

Re:Skycar

[TooMuchToDo]

How about dropping the vertical takeoff and landing requirement, and simply using general aviation airports? According to Wikipedia, there are 5,288 GA airports in the US.

Re:Skycar

[micknz]

And to do that we just need to suspend the laws of physics. Unless you know of another way of lifting 2,000 lbs straight up in the air. Sylar can do it, why can't we?

Re:Skycar

[mpe]

No, what's needed is vertical take off and landing vehicles for that price which don't make insane amounts of noise or vent extremely hot gases in a way that is dangerous to third parties.

The only way you get vehicle capable to taking of vertically is by having a thrust to weight ratio of greater than 1. Ideally thrust significently greater than the weight of the vehicle (including pilot, passengers and luggage). The only easy way to do this is by moving a large amount of air.

Re:Skycar

[shmlco]

My point exactly. "He claims." No photos. No videos. No demos. You'd think, as many times as it's been "featured" on shows like 20/20 and FutureCar, that "somebody" would have gotten a demo.

Nope, it's probably as functional as the clay model concept car I saw at a local auto show...

Re:Skycar

[SkyDude]

Of course not everyone should be allowed to pilot/drive a flying car.

Are you saying some people can't drive safely? What's wrong with hitting the gas when it was the brake they meant to hit? That would be no problem at a few hundred feet up, would it?

Re:Skycar

[tsalaroth]

Unless he only has 5% body fat - it could be all muscle. Wait, this is /.

Hmm.

Re:Skycar

[Anonymous Coward]

That's almost as funny as your mom throating elephant cock!

Re:Skycar

[BVis]

Not to take the wind out of your sails (your point is well taken) but most "serious" health professionals regard BMI with about as much respect as phrenology; it's pretty meaningless. 6'1" and 250 isn't unrealistic IF your body composition is sane. (Body composition is the percentage of fatty tissue versus lean mass in a human body, and is a far better indicator of a healthy weight.) If he's 6'1" 250# and has a body fat percentage under 10% (3% is bare bones(pardon the pun) essential for males, 15% is essential in females) then he's at a completely healthy weight for his height. If he's 6'1" 250# and his body fat is 30%, then that's a whole different story, and is at risk for obesity-related health problems.

Like so many other things in the health and fitness industry, nobody wants to look for the shades of gray or give people answers that they don't want to hear. For example: To lose fat weight, you must eat less (fewer calories) and exercise more. That's it. No fancy diets, no Atkins bullshit, no seaweed wraps, vibrating belts or other crap. BMI is a classic example of that. It's a number that is easily compared to an arbitrary scale, with math that isn't hard enough to make Joe Sixpack's eyes glaze over. The effort involved in body composition testing (Dunk tank best, caliper measure less so but more convenient, circumference measurement about the same, body conductivity most convenient but least accurate) is too great for most people to even consider unless they're forced.

There's more to measuring appropriate weight than height vs. weight. But like so many other things, nobody wants to hear that. And there's no money in telling people what they don't want to hear, so you'll never hear the fitness media conglomerate talk about it.

(I have a degree in exercise science, but work in tech because I refuse to work in an industry that I've found to be based on scams and diet pills.)

Re:Skycar

[kmac06]

Maglev! Discover a room temperature superconductor, spray it on all the roads, and have a giant electromagnet in your plane.

Re:Skycar

[GooberToo]

He wants the plane to fly itself. (He also requires what amounts to a complete revamp of the ATC system, but NASA and others are already researching something similar to his needs in that arena)

Then don't hold your breath. Funding for the next found of ATC/FAA restrucuring is going before Congress this year. Based on the currently announced plans, it will take 10-20 years before all planes adopt the new ADS-B technology (Info here or here. That means several decades before Moller's car can hope to fly its self. And if he requires something other than GPS and ADS-B, then his car won't be off the ground for two plus decades, easily.

Re:Skycar

[GooberToo]

I have seen a video of a Moller Skycar during a tethered flight. What a joke. It never left ground effect and its stability was a smoldering pile waiting to happen. I'm sure that is why you don't see it and that is why it is not generally available.

In fact, his project has all the earmarks of the flying saucer efforts (Avro Aircar) efforts during the 50s. The only improvement Moller has over Avro's efforts is it uses less fuel and the risk of falling into the propulsion system is greatly reduced. Aside from that, neither has left ground effect.

Re:Skycar

[LWATCDR]

"I don't know about the concept: a flying wing four feet wide, eight feet long, and only 400 mph seems a bit ambitious to me, but if the math supports it..."
It doesn't The power to weight ratio required is way more than you could get from any internal combustion engine that is reliable enough for manned flight.
It has hovered but how much fuel did it carry? How much load?
The control system is an excuse. Set it up for a conventional pilot if that is possible.
Frankly the Skycar makes the BD-5 look like a great success.

Re:Skycar

[jdray]

It's tethered, but... http://www.moller.com/medi.htm#

I'm not saying that Moller isn't something of a crackpot, and I suspect that he makes just enough progress to keep the investments rolling in without having to actually produce something viable on an automotive lot. However, he is making progress, and there may be a market for the vehicles if they work even half as well as he touts.

Re:Skycar

[tompaulco]

I'm also 6'1" and I weigh 200 pounds. I am not obese, but I am definitely overweight.

Re:Skycar

[joto]

and there may be a market for the vehicles if they work even half as well as he touts.

You mean, if it's able to fly... halfway?

Moller isn't a crackpot. He's a fraud. How he manages to milk investors for money to his 30 years in the works and billions burnt and all he has to show for it so far is an aborted tethered hoover demonstration is beyond me.

If Moller had started with something that flies, and gradually improved it with safety features and VTOL, he might have had a flying car decades ago. As it is now, there is no other way of viewing him, then as a complete fraud. Not only is he failing, and has been failing for the last 30 years. He is still taking investor money, and even continues to sell his "flying car" to customers.

Re:Skycar

[mazarin5]

You know, I was just explaining this last night to a group. It's along the same fallacy of everybody having the same ideal weight. It tries to improve by introducing a single variable: height. How tall are you? Here's how much you should weigh. Are you a 20 year old pencil neck? Are you a 60 year old 3 foot wide bodybuilder? If you're the same height, then you should weight the same! According to the BMI, I'm obese for my height. I really need to cut down on my excessive 19% body fat! It's one of those situations where the BMI is only good for people who are obviously not fit. The closer you are to the "ideal" weight, the less accurate it is. It's redundant in a way, because if you know the BMI chart might be useful to you, it's because you already know you have to lose (or gain) weight. For people close to fit, I try to use a chart that at least takes into account their frame size, and gives a proportionate category. If I have a ruler around, and the chance to pinch people, then I calculate their body fat % and use it along with their current weight and age to help them figure out what they need to lose, and the furthest that they should go. But you're absolutely right, it comes down to eating less and exercising more. People need to ease into exercising. I don't know how many people I've seen sitting on their groove in the couch, deciding that they're going to do 50 push-ups every day and run 5 miles. Guess how long before they're back on the couch because "it's too hard!"? My usual advice is that you find something that makes you breathe hard, but not so hard that you run out of breath. Do it for as long as you can. If that means jumping rope 5 times, then fine. If that means jogging for 100 feet, then fine. Eventually, it will be 500 feet, then maybe even a mile or two in the future. I think another problem is that people expect instant results. It doesn't help that going from sedentary to active will see some pretty big results right away, but then it slows down as you reach a new equilibrium. Then it's time to eat less and exercise more, again. It think a lot of people expect to shed their fat like they're a snake shedding it's skin. Sorry, it looks like the BMI put me in rant mode...

Re:Skycar

[Anonymous Coward]

You're kidding, right? Every motherfucker on the street knows BMI has to do with both fat and muscle, and is only a loose guide with the assumption of typical musculature.

I also think every motherfucker on the street knows people in Slashdot don't lift anything more than the Twinkies to their mouths. 250 6'1 could be healthy if the guy is a professional athlete but that isn't true.

BMI as a concept is not a subversion of the eat less - exercise more dynamic. It's a general weight guide to give people a vague idea of their ideal weight.

Unmanned, most likely

[stratjakt]

I know fuel cells don't make a whole lot of power, ie; you're unlikely to ever see them power big rigs.

Anyone got any good data on the power they do make?

Re:Unmanned, most likely

[Timbotronic]

TFA doesn't mention the power of the fuel cell but it does say it's not sufficient for takeoff and climb - just maintaining cruise. In order to climb, the motor needs additional power from a Li-Ion battery pack. I figure there'd be some potential safety issues with that. If you used up all your "climb power" you'd essentially have to rely on a glide approach for landing or maintain cruise until the fuel cell could recharge the battery enough for a "go round".

It'd be good to know what kind of power delivery would be required to eliminate the battery completely. I guess weight is the major obstacle at the moment.

Re:Unmanned, most likely

[jdray]

I guess weight is the major obstacle at the moment.

It is. Current (pardon the pun) PEM fuel cell technology typically uses platinum, AFAIK. Stacks are heavy. The Ballard Mark 1030 provides about 78 Watts per liter of unit volume and 66 Watts per kilogram. The Ballard Mark 902, which is used in several fuel cell cars and buses, is much more powerful at 1133 Watts per liter of unit volume and 885 Watts per kilogram, but it's heavy (96 kilos, over 211 pounds). Note that neither of these devices weights include the power conditioning and management systems, fuel handling, etc. The entire integrated stack is much heavier when you're considering a "hydrogen in, electricity out" system. Furthermore, if you're not supplying fuel from a bottle of anhydrous hydrogen (a strange phrase if I've ever heard one), you've got a fuel reformer to take into account, which is one more package of weight and one more power draw on the system.

Having said all that, I think this is a great idea and hope it succeeds. From what I know (or think I know), so-called "ultracapacitors" are much lighter and more responsive than Lithium Ion batteries, and other slow-and-steady power generation systems, such as zinc-air batteries, might be able to back them up with better success.

Re:Unmanned, most likely

[monsted]

APC makes a Fuel Cell generator for the data center. 10 kW in a medium-sized suitcase, if i understand correctly. It'll eat a six foot tall can of hydrogen an hour, though, so you'll need a pretty big tank.

Sony

[Anonymous III]

Cool as long as Sony aint involved, Hehe BOOM!

Skycar

[BigHungryJoe]

Has anyone ever seen a Moller Skycar in operation anywhere? Outside of air shows and conventions?

Ratios

[El Torico]

Are the power to weight ratios comparable to current internal combustion engines? If so, great! If not, what about fuel cell powered dirigibles?

More kinetic energy is bad

[dsanfte]

Unless we're looking at some kind of computer-only piloting, a personal "skycar" would be a very bad idea. That's way too much kinetic energy in the hands of John Q. Public. You think car accidents are bad now? Wait for a midair collision that takes out a whole apartment block.

Re:More kinetic energy is bad

[retro128]

That's way too much kinetic energy in the hands of John Q. Public.

I believe that's what they said about the automobile 100 years ago.

Re:More kinetic energy is bad

[Loke the Dog]

And automobile accidents is actually a big deal today, so I guess they were right too.

Re:More kinetic energy is bad

[QuantumG]

Here's an idea, how about you making decisions about what you want to buy and leave me to make decisions about what I want to buy.

Re:More kinetic energy is bad

[Anonymous Coward]

a 2000lb aircraft isn't taking out an apartment block anymore than a 2000lb truck would.

I would go so far as to say that most of the kenetic energy in a midair is lost before the aircraft hit the ground. It would depend on how the aircraft come into contact. Usually the 2 airframes become tangled, and they fall straight down.

Re:More kinetic energy is bad

[dsanfte]

That 2000lb aircraft is going to have two or three times the horizontal velocity of that truck, and an additional vertical velocity component when it impacts the ground.

Given the relation p = m v, you do the math on that, and couple it with the fact that no non-military building I know of is built to withstand impacts from above. Anyone in a home or apartment that's hit by a falling, fast-moving aircraft is dead meat.

Re:More kinetic energy is bad

[stratjakt]

How would two of todays light aircraft colliding take out a whole apartment block?

kinetic energy.. heh, your science teacher getting to physics?

Besides computers do all the flying these days.

Re:More kinetic energy is bad

[Asmandeus]

Yeah... ever since I was young and heard the promises (and lies!) of near future sky cars I thought to myself that it'll never work until our buildings are made of something way harder and durable enough to withstand everyday "wear" of average people flying around.

I can just imagine people escalating the occasional "car drives into house" by entering through the roof.

Re:More kinetic energy is bad

[mgv]

And automobile accidents is actually a big deal today, so I guess they were right too.

Considering that 3000 people die per day from car accidents around the world, what we have is a disaster of the proportion of september 11, done daily.

Generally speaking, most countries seek to blame the individual driver. Most airlines seek to fix the system. And when you look at what they have had to do to make planes safe, its pretty clear that few of us really have a right to lift a few tons of metal into the air over any place that people are.

The real question that society needs to ask is how much it can justify letting so many people drive cars right now.

Just some food for thought. Wont really matter too much anyway, the oil will probably get too expensive before many people can afford this sort of technology. We will need what is left to fly the efficient, big planes.

And no, I would be bitterly opposed to people having flying cars, even if the technology made it possible.

My 2c

Michael

Re:More kinetic energy is bad

[QuantumG]

Maybe, just maybe, 3000 dying a day is acceptable because of the massive public good of swift personal transportation. But you're probably one of those people who thinks nothing can justify accidental deaths, let alone willful killing.

Re:More kinetic energy is bad

[Anonymous Coward]

Wait for a midair collision that takes out a whole apartment block.

You mean like that idiot of a baseball player who crashed his high-performance small airplane into a New York apartment building and did nothing but start a small fire and get himself killed?

Light airplanes are marginally more dangerous than automobiles for the occupants. For everyone else, they are unequivocally safer by a large margin. There's no reason to expect a "skycar" to be different, except to become even safer for the occupants as well in order to survive product liability litigation.

Re:More kinetic energy is bad

[macshit]

Maybe, just maybe, 3000 dying a day is acceptable because of the massive public good of swift personal transportation.

Well the thing is that "swift personal transportation" as embodied by current automobiles really isn't much of a "public good" in many cases. Automobiles are well suited to sparsely populated rural environments, and very poorly suited to densely populated urban ones. The fact that they nonetheless are the standard transportation method in many large US cities is largely due to lack of forethought, blind herd instinct, and the power of fashion. I'm not sure those things are worth many deaths...

Re:More kinetic energy is bad

[mgv]

Maybe, just maybe, 3000 dying a day is acceptable because of the massive public good of swift personal transportation. But you're probably one of those people who thinks nothing can justify accidental deaths, let alone willful killing.

Before you make too many assumptions about me, let me reflect this back on you:

Do you think that the mass good of air travel justifies the occasional deaths of 3000 people when a few planes fly into buildings?

If that isn't acceptable, then why should this occuring on a daily basis be ok with cars?

Anyway, before you assume that this means that I hate motor cars:

My wife and I share a car. Its a wagon. I ride a bicycle to work most days. The wagon lets me throw my bicycle into the car easily when it rains or whatever.

I love being able to drive places and the freedom that this brings. However, when you look at the carnage that cars produce, I find it impossible to say that this level of death is justifiable.

Now there are two solutions to this problem, and one of them is to stop driving. The other is to look at the whole system of driving. Just like the aeroplane industry did 20-30 years ago, when planes killed alot more people than they do now. I'm really glad that action was taken back then, it produces the safety that we have today. We have done this to a great degree with cars also, but have not gone anywhere near the safety levels of flight. Much more needs to be done. To oppose this is to say that its ok to have thousands of people die daily because you can't be bothered to fix the problem.

When thousands of people die from other causes, it gets much more interest.

So, yes, I like cars, at least in theory.

In practice they are killing alot of people, and consuming huge amounts of non-renewable resources to keep them running. At least the latter is probably fixable, and I look forward to the day I can buy a true electric car. The former is a really hard problem, but to ignore it is also crazy.

Does that put my position in perspective?

Michael

Re:More kinetic energy is bad

[QuantumG]

Yes.. in fact, I think it takes a lot more than 3000 deaths to justify the insanity that we have to go through whenever we want to fly. I think the grand total number of deaths due to flying is woefully inadequate to justify the massive concern for "safety" that the airlines are required to exhibit. I think that flying would be more routine and a hell of a lot cheaper if it was more dangerous and people would willingly pay for such a service if only their governments would butt out.

Re:More kinetic energy is bad

[mgv]

Yes.. in fact, I think it takes a lot more than 3000 deaths to justify the insanity that we have to go through whenever we want to fly. I think the grand total number of deaths due to flying is woefully inadequate to justify the massive concern for "safety" that the airlines are required to exhibit. I think that flying would be more routine and a hell of a lot cheaper if it was more dangerous and people would willingly pay for such a service if only their governments would butt out.


Well, at least you are consistent.

Call me when a car (or plane) injures you or kills a family member, and explain to me then why you think its ok for your family members to suffer because someone else wanted a cheap air ticket or joy ride.

Personal freedom is fine, until (for example) I want the personal freedom to injure you.

Unless you think that is ok too...

Michael

Probably just feeding the trolls here now.

Re:More kinetic energy is bad

[QuantumG]

People know the risks of living in the modern world. If they can't hack it, go live in the freakin' woods or something.

Making emotional arguments like that really doesn't befriend you to a geek audience.

Re:More kinetic energy is bad

[TooMuchToDo]

Hey there chief, you are aware a private pilot's license only requires 40 hours of in-flight time, correct? I myself am training for my private license, have 12 hours of flight time, and have already solo'd (flying minus the instructor). General aviation has an accident rate of about 1 fatality per 100,000 flight hours (much safer then driving) although I agree that the barrier to fly is much higher then driving (which helps the accident rate).

Re:More kinetic energy is bad

[Anonymous Coward]

> Here's an idea, how about you making decisions about what you want to buy and leave me to make decisions about what I want to buy.

When the thing you wish to buy can endanger public safety and security it is the community who decides. Your freedom does not cover the right to hurt others' freedoms and security (e.g. their right to live). If the aircar proses a real accident or terror hazard than the govt has right to ban it outright or mandate stringent skills and allegiance tests for drivers.

Just like the gov't can and does ban full-auto weapon trade from citizens due to massive destructive power, there can be limit on the kind of aircars available to laymen.

Re:More kinetic energy is bad

[mgv]

Hey there chief, you are aware a private pilot's license only requires 40 hours of in-flight time, correct? I myself am training for my private license, have 12 hours of flight time, and have already solo'd (flying minus the instructor). General aviation has an accident rate of about 1 fatality per 100,000 flight hours (much safer then driving) although I agree that the barrier to fly is much higher then driving (which helps the accident rate).

Of course, if everyone was flying around up there, there would be alot more collisions...

I'm pretty sure its more than 40 hours in Australia...

But I'd generally agree with you - flying is safer than driving.

Its the damage to society that cars do that troubles me - I've seen too much road carnage to ignore the down side of driving. Too many people in wheelchairs, or having lost limbs, or had their brains injured. Or worse.

Much less problems with flying, other than how to keep planes in the air as fossil fuels run low...

Michael

Re:More kinetic energy is bad

[ChrisMaple]

Small airplanes can have 50 mpg economy and do 120 mph. They make sense in open areas like the plains states.

You would be bitterly opposed to this, which would be fast, economical, safe and fun? You must really hate human beings.

Re:More kinetic energy is bad

[mgblst]

Do you live in a society, or on your own island somewhere. You already have limits on what you can buy, and I don't see that as a bad thing? Or should anybody who can afford one and wants one have their own nuclear bomb? Or tank? Or lump of plutonium?

Re:More kinetic energy is bad

[Anonymous Coward]

Actually, the American full auto ban was enacted because of 30s Chicago mob films, and no governments (being governments) have retracted it since.

It's all about public perception, not actual safety.

Re:More kinetic energy is bad

[khallow]

Keep in mind that most such deaths occur in the Third World which is notorious for bad traffic laws and infrastructure. In the US it's somewhere around 100 deaths per day despite our far greater miles driven per capita.

Reliability?

[mcrbids]

One of the biggest problems with smaller aircraft is reliability. Simply put, piston engines are not as reliable as jet engines. They must be rebuilt every 2,000 hours of flight under the best circumstances. And, with smaller planes at slower speeds, jets just don't make sense.

Turboprop engines are a good middle ground for mid-sized planes starting at the 12-seat size or so, but are very expensive for the smallest aircraft. (2 and 4 seaters)

Electric motors, other the other hand, can be incredibly reliable. If designed for it, they have just a single moving part, and can run continuously, 24x7x365 for many years without issues. This kind of reliability in a small plane would be just incredible!

Re:Reliability?

[YrWrstNtmr]

This kind of reliability in a small plane would be just incredible!

Just as with cars, power density is the sticking point. And even more than cars, weight is an issue. Taking the standard Cessna 172:
Fuel capacity of 42 USG.
Range 790 miles.

Assuming the gas and electric engines weigh the same, and assuming 6lb per gal for Avgas....can we build a battery pack good enough for 790 mile range, with NO loss of power over that range, that weighs 250lbs?
(The Prius battery pack weighs about 1/2 that - 45kg))

Re:Reliability?

[CustomDesigned]

The Moller Skycar uses rotary (Wankel) engines. One main moving part (rotor) each. It uses 8 of them, 2 in each of 4 rotating pods. It can lose at least 3 engines and still maintain stable flight (after that it depends on which you lose). There is also a parachute for the entire vehicle as a last resort.

The Wankel engines are much smaller and lighter for the same horsepower than piston engines. Their drawback for automobiles is similar to turbines - they don't like low RPMS (the rotor seals leak at low RPMS causing wasted fuel, seal wear, and pollution). This is not a drawback for aviation.

Of course, this design requires fly by wire computer control for everything, and you don't want your computer to fail (although the parachute could be manually deployed).

Re:Reliability?

[ppanon]

can we build a battery pack good enough for 790 mile range, with NO loss of power over that range, that weighs 250lbs?

No, but that may be why they're looking at fuel cells which have different performance characteristics than battery packs.

My guess is that they really want to use it for military/police UAVs where getting rid of the noise from a combustion engine will seriously improve stealth operation modes. Smaller surveillance-oriented versions could perhaps be dropped from a mother ship and have smaller range requirements than you indicate.

Re:Reliability?

[Anonymous Coward]

Reliabilty is not really a problem with piston engines. I own and fly a C182. I routinely get 2000 hours between overhauls. In fact my last time around I got 2400 hours before oil analysis showed traces of bearing material. Since I cruise at 160 MPH, that's 384,000 miles between overhauls. You would be hard pressed to find an automobile that gets that kind of mileage without major engine work.

Even turbine based engines such as the PT6-60A's on our King Air's rarely go 3000 hours. Those extra 1000 hours you get on a turbine, come at a great cost. Our last PT6 overhaul cost a shade over $325k. By comparison, I paid about 18k for my last overhaul.

Re:Reliability?

[Anonymous Coward]

The Moller Skycar uses rotary (Wankel) engines. One main moving part (rotor) each. It uses 8 of them, 2 in each of 4 rotating pods. It can lose at least 3 engines and still maintain stable flight (after that it depends on which you lose).

As far as I am aware, the Moller Skycar has never demonstrated any kind of untethered flight at all, much less stable flight, and certainly not stable flight with three engines out. How can you possibly claim that this machine can maintain stable flight under these extreme conditions when there is nothing remotely resembling proof?

Re:Reliability?

[mcrbids]

Compare that to 43,800 hours that you could easily get with an electric motor with the capacity to run for just 5 years 24x7.

Yeah, you're happy. But airplanes are too expensive to be available to the common man. Few people have the $18,000 to rebuild your 182, let alone the $325,000 to rebuild your King Air. Result? Your beloved 182 costs something like 5x the cost per hour to operate as an average car, and has a safety record that's considerably worse. Statistically, single-engine piston planes are somewhere between a car and a motorcycle in safety per hour, somewhat closer to a car in safety per mile of travel due to the higher travel speed.

Anything that improves this mediocre record is a good thing.

Full Disclosure: I'm a solo pilot due to take my checkride sometime before the end of April, according to my CFI. I love flying, and am trying to figure out how to make it make financial sense as the father of 6 kids despite my 6-figure income.

Re:Reliability?

[mpe]

Electric motors, other the other hand, can be incredibly reliable. If designed for it, they have just a single moving part, and can run continuously, 24x7x365 for many years without issues. This kind of reliability in a small plane would be just incredible!

Electric motors still need to get their power from somewhere batteries arn't that good for storing large amounts of energy nor are fuel cells that good in the 10-100's kW range. You'd probably be better off with an internal combustion engine driving a generator.

Re:Reliability?

[GooberToo]

I hate to be pedantic, but a range of around 430 miles seems much more realistic for a 172 on 42 gallons. I don't have a 172 POH here but if you really pull the throttle back to get extra range, chances are it will be faster and cheaper to simply drive unless you have a heck of a tail wind.

Feel free to cross check what I'm saying at this website.

Re:Reliability?

[CustomDesigned]

It seems that Moller has never gotten the computer control part right over 12 years. Sad. But the mechanical design is good. In another 5 years, his patents will expire, and someone can finish the job.

Bah.

[rackhamh]

Their heads are in the clouds on this one. This project will never fly. I bet it stalls and they never get it off the ground. It simply flies in the face of reason. That said, the sky's the limit when it comes to technological fantasy.

Re:Bah.

[Hektor_Troy]

I bet it stalls and they never get it off the ground.

Technically if it stalls it's already off the ground. You might have meant that it stalls and crashes and burns.

Don't cross the road if you can't get out of the kitchen. And remember - a penny saved is worth two in the bush.

Re:Bah.

[Cornflake917]

Who gives a flying fuck?

Blimps could be quiet

[Soong]

But there just aren't good places to park all those cubic meters of helium each of our blimp-cars would need.

So, engine noise and laminar flow ducted fans? However you do it, flight needs a lot of power and it's going to get all that power to be smooth and quiet.

Re:Blimps could be quiet

[maxume]

We just need a way to hide stuff from gravity. If you could generate the force, you could probably hide a mass the size of a car with a nine volt battery.

Re:Blimps could be quiet

[Colin Smith]

But there just aren't good places to park all those cubic meters of helium each of our blimp-cars would need. Or you use hot air.
http://www.personalblimp.com/

Of course, sky yacht is a more apt description than air car.

Parking space... Pick a field. Not exactly commuting material, more trip round the world material.

Use a compressor

[CustomDesigned]

But there just aren't good places to park all those cubic meters of helium each of our blimp-cars would need.

Pump the helium (or hydrogen - that wasn't what started the fire on the Hindenber, although it certainly made it worse once it ignited) into tanks to descend. Release it into the gas bag to ascend. Pump it all into your tanks and fold up your envelope to park. Submarines do something like this with air.

Re:Use a compressor

[stratjakt]

Dont you watch mythbusters?

It was the helium. It was not painted with thermite.

Re:Use a compressor

[Miseph]

You mean hydrogen... helium is incredibly stable and does not combust at any temperature we would consider to be "normal" outside of a dying star.

Re:Use a compressor

[Anonymous Coward]

I very much doubt that the helium burned.

Ultralights

[MobyDisk]

I know nothing about engines, so can someone answer some basic questions for me? Wouldn't a fuel-cell engine be essentially an electric engine? Would it be quieter than a gasoline engine? More reliable? Would there be any odor? If so, they would be ideal for ultralights:

I am a hang glider pilot, and I would love to have a small engine for it. There are several manufacturers who make small engines for them, they are loud, stinky, gasoline engines. Most of them only hold 1-2 gallons of fuel, which is plenty for this type of flight. Wouldn't a fuel-cell engine do the trick?

Re:Ultralights

[YrWrstNtmr]

they are loud, stinky, gasoline engines.

An awful lot of that noise is the prop, not the actual engine.

Re:Ultralights

[myrdos2]

Wouldn't a fuel-cell engine be essentially an electric engine?

-Yes, the fuel cell takes in hyrodgen and outputs electricity, which runs an electric motor.

Would it be quieter than a gasoline engine? More reliable?

Yes, and yes. Electric engines are virtually silent, and have far less moving parts than internal combustion engines.

Would there be any odor?

No, the only output from a fuel cell is water vapour.

If so, they would be ideal for ultralights:

Maybe! Your main problem here is fuel density. On the one hand, electric engines are around 95% efficient, compared to gasoline engines which are around 35% efficient. On the other hand, hydrogen isn't very dense - a liquid hydrogen tank requires roughly three times the volume of a gasoline tank with similar energy. (It also needs to be very well insulated) And by eyeballing the picture, it looks like they're using a compressed tank, not liquid. Probably one of those new 10,000 psi tanks, this being Boeing. Even at that pressure, the energy density's going to be a lot less than liquid hydrogen.

I note that they don't mention the range or price, which are going to be very small and very large, respectively. A fuel cell alone can set you back 30,000$ US. The cheapest I've seen for a complete system that can power a car is $60,000 US.

Re:Ultralights

[DayBoyUSA]

All the fuel cells I have worked with run very quiet. The loudest noise is the fan bringing air into the unit and that is about as loud as some of the PCs I have used. The exhaust is pretty much air + CO2. I would imagine that fuel cells could provide significantly more power per weight than a battery. The fuel cell will provide electricity, so all you would need is an electric motor.

Re:Ultralights

[jdray]

I think the important question is, "Given a (two stroke) gas engine and full (two gallon) fuel tank, what would the power of a fuel cell/electric motor system be for the same amount of runtime?" I think the answer is "Not much." Two stroke (noisy, stinky) gas engines are very good at converting fuel into mechanical power. You just pay for it in environmental damage, not only in noise and smell, but in toxicity.

Re:Ultralights

[Anonymous Coward]

Actually, a really good four-stroke gasoline engine only reaches a peak efficiency of about 25%, but is typically much less efficient in regular use. The old-fashioned carburetor engines we're talking about here are way more inefficient. The most efficient combustion engines available are turbocharged diesels with high-pressure direct injection, they reach an efficiency of around 45%.

Re:Ultralights

[Thuktun]

Wouldn't a fuel-cell engine be essentially an electric engine? Would it be quieter than a gasoline engine? Engines that use combustion fuels are powered by bursty or continuous explosions. Explosions are inherently noisy.

Moller

[zippthorne]

Heck, I'll be happy if we can get the regular version of mr. Moller's skycar.

It's not the engines which are noisy

[M0b1u5]

It's not the engines which are noisy on Moller's ultra-dangerous thing (I refuse to dignify it with the title "car" or "aircraft" as it is neither) it's the fans/propellers which make all the noise. You simply can't move lots of air without making a hell of a racket.

See: Overclocked PCs, Helicopters, Jet Engine, extractor fan, air conditioner, Vacuum cleaner...

It wouldn't matter if Moller's thing had fuel cells - it would just as noisy.

Re:It's not the engines which are noisy

[DigiShaman]

See: Overclocked PCs, Helicopters, Jet Engine, extractor fan, air conditioner, Vacuum cleaner...

None of these applications have blades that are acoustically optimized either with the exception of some CPU HS Fans and military copters.

I wouldn't put it out of the realm of possibility that the Moller's "thing" could be engineered to be more quite.

Re:It's not the engines which are noisy

[M0b1u5]

Acoustic optimisation can onyl get you so far. In other words, you reduce fans/propellors from "an ear damaging roar" to simply "extremely fucking loud". There's only so much you can do to quieten fans;

You can get cute and use TMD (Tip Magnetic Drive) fan blades, which have no ends (its thought that tip vortex at the end of fan blades is responsible for much of the noise associated with fans and blades) and you could spend millions designing the most efficient blades possible.

Hell, you could even bet that in a few years the next generation of memetic polyalloys (T1000 et al) or "memory metals" will even allow the actual blades to change shape depending on their rotational speed, thus reducing noise still further.

But the fact remains, on a 2000 KG car, you need at least 2000 KG of vertical thrust to keep it in the air, and 2000 KG of thrust is a LOT. Are you seriously suggesting that fan blades can be made as quiet as say - a 5-litre V8 car at 6000 rpms? No way. Not gonna happen. Not ever.

Unless some way can be made to shift large amounts of air, efficiently, with no blades at all, then the Moller thing will never be anything more than a fucking dangerous, extremely noisy experimental demonstrator.

I'm still hanging out for effective anti-gravity. After all, it's such a weak force, that 2 AA batteries should be powerful enough to keep your car airborn for a year or so. Then all you need is some way to move it about, and you only need one engine for that - so it'd be much quieter.

Re:It's not the engines which are noisy

[Anonymous Coward]

What about, erm, what are they called....cylons? Or whatever the term is; you know, those things on certain helicopters where the tailrotor is caged in. Apparently those make a LOT less noise.

Re:It's not the engines which are noisy

[mpe]

But the fact remains, on a 2000 KG car, you need at least 2000 KG of vertical thrust to keep it in the air, and 2000 KG of thrust is a LOT.

That's 20,000kN just to keep it in the air. You need more than that to get it into the air in the first place. You also need a decent amount of thrust to be able to go anywhere, possibly make that thrust vectored so you can use it to either climb or move in the horizontal plain.
There is also the problem that if you lose your lift thrust you are likely to crash. A parachute will only be of use above a certain altitude.

Re:It's not the engines which are noisy

[ChrisMaple]

Gliders are relatively quiet, and their wings are still providing lift. The aircar problem is that the total lift area is small and compact, so that it requires a great air velocity change to get adequate lift. Making the big velocity change causes noise.

Re:It's not the engines which are noisy

[uradu]

Actually, it's not the movement of air as much as you think. With all the "noisy air mover" examples you listed, the majority of the noise comes from the bearings in the electric motors and whatever they drive. Disconnect the belt in your vacuum and see if it gets much quieter--it most likely won't. Check out noisy power tools such as table saws and routers, it's almost always the bearings making all the racket. With PCs you can really notice that when the bearings in a fan go bad--the low noise that was always there at a muffled level suddenly gets loud and shrieking. =

ha ha

[Quadraginta]

Are the power to weight ratios comparable to current internal combustion engines?

You probably mean the external combustion engine, also known as the jet engine. Only small airplanes use pistons and such. And the answer is: of course not. This is yet another PR stunt aimed at the Gasoline Is Eeeeeeevil ninnies of the world who failed freshman chemistry.

If not, what about fuel cell powered dirigibles?

I don't think the problem with dirigibles is how to power them. I think the problem is that there's just about zero demand for a transport service that's about as slow as a ship or train but neither as efficient nor as reliable.

A big cargo ship carrying 70,000 tons of cargo can cruise at 15 knots with its 50,000 HP engines running at 80%. The EPA helpfully estimates big marine engine fuel consumption as about 250 grams per kilowatt-hour, which lets you work out that a cargo ship consumes about 4 grams of fuel per ton of cargo per kilometer traveled.

Four locomotives pulling a hundred-car freight train at 60-80 MPH, with each car carrying 100 tons of cargo, will burn about 7.5 gallons each per mile. That works out to 7 grams of fuel per ton of cargo per kilometer traveled.

There's no way any vehicle that flies can ever come close to that kind of fuel efficiency. So who would want cargo delivery that's just as slow, but much more expensive?

Re:ha ha

[modecx]

You probably mean the external combustion engine, also known as the jet engine. Only small airplanes use pistons and such. And the answer is: of course not. This is yet another PR stunt aimed at the Gasoline Is Eeeeeeevil ninnies of the world who failed freshman chemistry.

In what way, exactly, is a jet engine not an internal combustion engine?

Sounds like someone failed basic understanding-of-how-things-work class. Grandma, is that you? I thought I told you stop trolling slashdot, damnit!

Re:ha ha

[acramon1]

There's no way any vehicle that flies can ever come close to that kind of fuel efficiency. So who would want cargo delivery that's just as slow, but much more expensive? How about people who need to deliver cargo over terrain lacking waterways and railroads?

The nice thing about flight is that it doesn't require as much infrastructure. As long as there's a place to take-off and land (which, granted, may not be there), flight is a viable, and sometimes cost-effective, method.

Re:ha ha

[khallow]

Wikipedia claims the Hindenburg could reach 135 km per hour, which is comparable with modern cargo trains at full speed and substantially faster than cargo ships. I imagine a modern version could go quite fast compared to the above transportation modes. So it appears to me that there is a niche there that isn't covered by current shipping modes.

Re:ha ha

[mpe]

You probably mean the external combustion engine, also known as the jet engine.

A gas turbine is an internal combustion engine. The combustion chambers are between the compressor and turbine stages, more or less in the middle. About the only thing you could call an "external combustion engine" would be a reheat also known as an "afterburner"... AFAIK the only civil aircraft with such engines still flying is NASA's TU144.

I don't think the problem with dirigibles is how to power them. I think the problem is that there's just about zero demand for a transport service that's about as slow as a ship or train but neither as efficient nor as reliable.

Maybe you could cover the upper surface with photovoltaic cells and have a slow vehicle which didn't require fueling.

Re:ha ha

[Viol8]

"There's no way any vehicle that flies can ever come close to that kind of fuel efficiency."

Wrong. An airship with a decent tailwind can use virtually zero fuel except that required to reach a given height and adjustment thrusters. An airships fuel efficiency is completely unrelated to that of fixed or rotor wing aircraft. In fact even without a tailwing all an airship with neutral buoancy has to do is fight air resistance , unlike other aircraft which ultimately expend fuel to stay up in the air as well as move forward.

And before you say "but what about on the way back when its going into the wind" , ask yourself this - how do you think sailing ships ever make a 2 way journey?

Re:ha ha

[Viol8]

"About the only thing you could call an "external combustion engine" would be a reheat also known as an "afterburner"."

And steam engines.

Re:ha ha

[ChrisMaple]

Sailing ships make two-way journeys, even in the face of constant prevailing winds, because they can tack. They can tack because they get "traction" in the water and with angled sails can get a thrust vector partially into the wind. This is not the case with airships, where the choices are some combination of

• use fuel
• wait for the wind direction to change
• follow prevailing winds completely around the globe.

Re:ha ha

[homer_ca]

You mean like a sailing ship? :P

Re:ha ha

[emilper]

what about infrastructure costs? tracks, bridges, maintenance personnel etc.

I am not an engineer but shorter routes (don't have to use that pesky mountain pass, can just go over it), no railway maintenance, no bridges, no overpasses, no ground level noise look like a serious advantage. Getting higher speeds should be easier than with trains: only need a harder hull and stronger engines.

Dirigibles would be bulky, but I guess collapsible frames could be developed and the gas pumped out when parking, and the lost in weight on the road due to fuel consumption can be compensated. Dirigibles would find landing difficult in windy weather, but so do most of the planes.

Before the Hindenburg accident zeppelins were "the future" of long distance aerial transportation.

Dirigibles probably cannot supplant sea transportation, but for inland routes should work fine, I guess. The reason there is no strong interest is, I suppose, the fact that there is already a fine network of railways and sea lanes, and seeing people jump out of a flaming zeppelin did not help either.

Re:ha ha

[emilper]

they had regular transatlantic zeppelin lines ... did those follow the wind ?

giant rubber bands

[Quadraginta]

...or some kind of powered trampoline.

This isn't totally humorous, incidentally. Think of aircraft carriers. You can achieve very short take-off distances without putting the giant (noisy) vertical-flight machinery on your aircraft -- because you can just leave it on the ground behind you. But you must then accept the fact that you can only launch in certain places.

Still, I'd bet there's a market for a cheap skycar that can only launch at certain public facilities but can land nearly anywhere.

Re:giant rubber bands

[YrWrstNtmr]

But you must then accept the fact that you can only launch in certain places.

If you have the launch facility, you also have the landing facility. So we're back to the standard (cheap) Cessna.
Landing 'anywhere' = vertical landing. Loud, dangerous (crosswinds) and expensive on fuel.
Without some uber propulsion type (not fans pushing air), I don't see it happening any time soon.

Re:giant rubber bands

[Calinous]

Ships and submarines have launching facilities for cruise missiles. They miss landing facilities for them, however.

Re:giant rubber bands

[Anonymous Coward]

Ships and submarines have launching facilities for cruise missiles. They miss landing facilities for them, however. I strongly disagree - they have perfect landing places for them. It's called a "target".

time to educate the masses again...

[Quadraginta]

Go here and look at the nice picture on the right-hand side. Notice that the combustion takes place in the exhaust stream, heading out of the engine. Not inside a cylinder.

Sounds like someone failed basic understanding-of-how-things-work class.

Oh I agree, definitely.

Re:time to educate the masses again...

[Captain Nitpick]

Go here and look at the nice picture on the right-hand side. Notice that the combustion takes place in the exhaust stream, heading out of the engine. Not inside a cylinder.

Sounds like someone failed basic understanding-of-how-things-work class.

Oh I agree, definitely.

Somebody failed looking at pictures class. The combustion chamber in a jet engine is quite definitely in the middle of the engine. Combustion takes place inside the engine, between the compressor and the turbine.

Not all ICEs have pistons, nor are all piston engines ICEs.

Re:time to educate the masses again...

[modecx]

Notice that the combustion takes place in the exhaust stream, heading out of the engine.

Oh, so you mean jet engines are continuous flow internal combustion engines?

here's a clue, boy'o: which fluid is the working fluid in an internal combustion engine?

Answer(ROT13): Gur bar jurer pbzohfgvba gnxrf cynpr, qhzzl!

Re:time to educate the masses again...

[Nasarius]

Wow, arrogant and stupid.

jet engine
any of a class of internal-combustion engines that propel aircraft by means of the rearward discharge of a jet of fluid, usually hot exhaust gases generated by burning fuel with air drawn in from the atmosphere.

http://search.eb.com/eb/article-9106039

You fail it.

Re:time to educate the masses again...

[AikonMGB]

Your analogy is faulty; if you indeed look at "the nice picture" in the article you linked, you'll notice that the combustion actually takes place in the combustion chamber, between the compressor and turbine stages; the exhaust stream is produced as a result of this combustion. Furthermore, the article you linked to was for a turbojet engine, which is nothing but a sub-class of the jet engine.

A jet engine does not specify that the energy source must be an internal combustion engine; it only specifies that thrust is generated in one direction by expelling a fluid (usually air/exhaust or water) in the opposite direction. Having said that, most common jet engines do use internal combustion. It is simply a matter of type.

A common example of a jet engine that uses a reciprocating internal combustion engine (typically two- or four-stroke) for power can be found in Sea-Doos, where a standard reciprocating internal combustion engine (like you would find in most automobiles) is used to drive an impeller that expels a jet of high-pressure water rearward of the craft, propelling the craft forward.

A common example of a jet engine that uses a continuous flow internal combustion engine is a turbojet engine, commonly found on military aircraft, or turbofan engine, commonly found on commercial passenger aircraft. Both turbojet and turbofan engines share a similar design in that the incoming air is pressurized using a compressor, mixed with fuel and combusted in the combustion chamber, and then expelled rearward of the craft for thrust. In this exhaust stream you will find a gas turbine that is used to power the compressor. In the case of turbofan engines, this gas turbine will also power a large fan located at the engine intake, which is where the majority of the thrust in a standard commercial jet-engine comes from.

The important thing to note is that reciprocating and continuous flow engines are both types of internal combustion engines; the public is just used to thinking of the ICE as a two- or four-stroke cycle system using pistons and a crankshaft, which is just not true. The combustion chamber in a turbojet or turbofan (or turboprop, now that I think about it) engine is still a confined-space combustion chamber used to burn air mixed with fuel at high pressures.

While I'm sure that looking at pretty pictures helps grade-schoolers learn "the way of things", typically it is considered good practice to read up on a subject before putting someone else down about not understanding it.

And in case you were wondering, I am a 4th year Aerospace Engineering student at the University of Toronto. While I don't claim to know everything there is to know in the world of combustion engines, I have had a fair amount of exposure both from private study and from experts and researchers in the field.

Aikon-

p.s. No, Wikipedia is not a reference I would ever cite in a research paper, though in this area its information is pretty good. I link to it only because it offers a great overall explanation of the processes involved. If you are sufficiently interested I suspect you will be able to get your hands on some real study material that goes into much more detail.

Re:time to educate the masses again...

[Deadstick]

Splendid exposition, the best in this thread. I'll only add that this and this are external combustion engines.

rj

Re:time to educate the masses again...

[JabberWokky]

Orion and afterburners are as well (well, I'm not certain about the latter, and the former is only "combustion" in the loosest of general definitions, but it is external. Hopefully).

--
Evan

Re:time to educate the masses again...

[modecx]

Good jorb, I can mostly agree with this little writeup, save one part, which I feel is mostly erroneous:

A common example of a jet engine that uses a reciprocating internal combustion engine (typically two- or four-stroke) for power can be found in Sea-Doos [wikipedia.org], where a standard reciprocating internal combustion engine (like you would find in most automobiles) is used to drive an impeller that expels a jet of high-pressure water rearward of the craft, propelling the craft forward.

The engine in this instance is the reciprocating engine. The propulsor, a pump-jet, is a separate device, and is only related to a turbine engine (jet engine) in the most basic way. Sure, you might be able to call some such devices a "turbo pump", but that doesn't make a pump hooked up to a 2 stroke engine a "jet engine" any more than a paddle wheel makes an old river boat a jet engine powered craft.

Re:time to educate the masses again...

[modecx]

Orion and afterburners are as well (well, I'm not certain about the latter, and the former is only "combustion" in the loosest of general definitions, but it is external. Hopefully).

Actually, what defines internal/external combustion is what fluid happens to be doing the work. You have to ask your self, "Is the fluid where the combustion is taking place also doing the work in the system?" If the answer is yes, then you have an internal combustion engine. This means that everything from the largest rockets to turbine engines, with or without afterburners, to your lowly lawnmower engine are all in fact, Internal Combustion Engines. Obviously, the Orion is nuclear engine, not combustion, so it doesn't really fit into this, unless you count nuclear reactions to be a type of combustion... Such a description is superficially analogous, at least.

Some examples of external combustion engines: steam engines, whether they be powered by coal, oil, natural gas, wood, or nuclear sources (again, if you count fission as a type of combustion), Stirling engines, and any other externally powered heat engine that may be powered by burning something (or anything). In these cases, the heat source heats up the working fluids, and the working fluids do the work separately of any combustion process.

Re:time to educate the masses again...

[Deadstick]

Some of the combustion in an afterburner takes place outside the engine, but it contributes essentially no thrust...only the heat generated before or in the exhaust nozzle adds to the thrust.

Remember, a flame is a stream of gas hot enough to be ionized, not necessarily a region where combustion is taking place. The long flame of an afterburner is mostly gas that was reheated in the burner; since it comes out of the engine hot, it continues to expand, which represents wasted energy. That's why afterburners are used sparingly: they give a lot more thrust but burn fuel out of all proportion to it.

rj

Re:time to educate the masses again...

[AikonMGB]

Hmm.. I suppose it is a bit ambiguous where you draw the line between what is the "engine" and what is the "propulsor".. I tend to think of the entire drive-train (from powerplant to vehicle-medium transmission) to be lumped into the "engine" of the vehicle, but other views may differ. As for your analogy to an old river boat, I do not think that it is quite suited to this discussion. As far as I'm aware, the classical definition of a jet implies that the fluid effluent is under pressure, resulting in a coherent stream of the fluid through the medium (regardless of whether that medium is the same material as the fluid stream or not). In your example of paddle wheels, there is no stream of fluid propelled rearward. Sure there is a net momentum change, but the affected fluid particles are quickly absorbed back into the surrounding medium; in other words, the momentum imparted on these molecules is relatively small compared to the viscosity of the fluid.

In a jet stream, however, the net momentum imparted on the fluid particles is very high with respect to the fluid viscosity, resulting in a stream that persists far down-stream of the jet nozzle (which, if you want to get technical, I believe might be part of the definition of a jet.. not sure if you can have a practical jet without a fluid nozzle?). This can often be several times the length of the craft itself, as is the case with Sea-doos and, I believe, most turbofan/turbojet aircraft. The large difference in velocity/momentum between the jet and the medium prevents the re-absorbtion of the stream; you get boundary layers and vortices at the interface, but those effects dont' become noticeable until you are far down-stream of the jet nozzle.

I guess what I was trying to point out is that alot of the time we tend to think of a "jet engine" (or turbfan/turbojet engine) as being all one unit, while something like in a Sea-doo is entirely separate; ultimately, while the powerplants of "turbine engines" and pump-jet engines may differ, the basic concept in the sense of "they produce a jet of fluid to propel the craft" stays the same.

At this point though I would say we're getting pretty close to tomayto/tomahto ;)

Aikon-

Re:time to educate the masses again...

[JabberWokky]

Yep, I figured I might be corrected. I was under the mild impression that the fuel combusting behind the engine was the additional thrust generated by the afterburner (hence the name). I'm not terribly surprised to be wrong, since it's something I merely picked up at air shows. So the visual effect is wasted energy and a side effect, not the actual propulsion. Thanks for the clear explanation.

--
Evan

Electric Aircraft

[Sloppy]

Huh. Haven't heard of that before. That's pretty unusual, no?

Re:Electric Aircraft

[mjwx]

Not so strange, after you find out about this

Another Lightning Rod.....

[IHC Navistar]

Soon, the complete idiots who build their homes next to airports and then complain about all the noise will have another thing to whine about.

Re:Another Lightning Rod.....

[mpe]

Soon, the complete idiots who build their homes next to airports and then complain about all the noise will have another thing to whine about.

A pity Boeing can't build an aircraft that runs on hot air :)

Those Damn horseless carriages!

[ethicalBob]

Yeah, and those "horseless carriages" will never happen either! Communicating over WIRES? unHEARD of!

Cheap aircraft

[wasted]

You can get everything to build a Bradley Aerobat (very similar to a Teenie Two,) for less than $20,000, and since you build it yourself, you are qualified as your own mechanic. There are/were some on eBay for less than $10,000, but that is a non-turbo version.

Re:Cheap aircraft

[MBGMorden]

Or if you want to have an airplane with a little more "uumph", try the http://www.zenithair.com/zodiac/xl/index.html (I'm a builder in progress, but I don't work for them :)). Seats 2 large people very comfortably (by 2-seat airplane standards), cruises at 138mph, and can be built from scratch. The raw materials in the airframe can be had for about $8k. It accommodates a converted Corvair automobile engine (the 1964+ non-turbo one) EXTREMELY well. Figure in another $4k to buy a used one and rebuild it into an engine suitable for aircraft use. Basic instruments and radios another $3k (that's generous - you can get away with MUCH less if you want to).

So again under $20k (and a lot of personal time investment; 1200 to 3000 hours of build time, but a fun project :)) you can have a brand new, all metal, two seat cross country capable flying car, er, airplane :).

BTW the plane listed about is Light Sport eligible which means you can get licensed to fly it a bit easier than getting a regular pilots license (less medical checks, less time in getting license, etc).

You're a blimp, so stfu

[Anonymous Coward]

we're talking about airplanes asshole

Energy density is getting there.

[Animats]

Battery energy density is finally getting good enough for this sort of thing. Electric cars with real performance are at last possible, although the trunk full of laptop batteries still costs too much.

For aircraft, the price point is higher, so this could work. There are lots of little electric-powered unmanned aircraft around, from toys to small military recon units. An outfit called Aviation Tomorrow was making noise about an electric-powered kitplane back in 2002-2005. They got to the point where they'd announced the first flight test in 2005, then disappeared. What seems to have gone wrong is that they originally planned a battery powered plane, which would have worked, then switched to hydrogen and Ballard fuel cells, which didn't.

The embarrassing fact about the fuel cell industry is that almost nobody is shipping a usable product. It's still all prototypes. Five years ago, Ballard was about to launch a commercial product with Coleman, but they couldn't make it work well, and Coleman backed out. APC supposedly sells a fuel cell product for server backup power, but it doesn't really seem to be installed in any quantity. (For one thing, it requires chilled water for cooling, which is a real problem if you need power to chill the water.)

Re:Energy density is getting there.

[Anonymous Coward]

"Electric cars with real performance are at last possible, although the trunk full of laptop batteries still costs too much."

Laptop batteries on cars are an extremely bad idea. Imagine this: you are driving along, minding your own business, some other car crashes into yours and you explode. Nice uh?

Lithium batteries are sensitive to heat and impact (which can cause a short-circuit, leading to heat), and can explode. If you've seen pictures of exploding laptop batteries, now imagine an explosion with 30 times as many battery cells. It's like some kind of personal Hiroshima.

Re:Energy density is getting there.

[PermanentMarker]

Just for your information, i know that Germany is devolping their latest submarines on this type of (silent) feul-cell energy. I understand that a submarine is something different then an airplane. But when you consider that fuel-cell's are powerfull enough to speed a huge submarine underwater. Then this techknowledgy is seaming to break some past barriers.

Also I just mention that sciencedaily yesterday reported a batery type with 5 times more storage as a lithiom-Ion batery. Their device used sugar chemics, as a way of storing energy. So it is likely the knew energy holders are awakening in our pre-green-industrial revolution.
For sure we see this also in future cars, allready some car manufactures have electric driven cars available for the grant public (beyond the point of science, such cars are sold these days i mean).

(Note that the technical details of the german fuel-cell device are stil a militairy secretcy.)

Re:Energy density is getting there.

[Acer500]

Lithium batteries are sensitive to heat and impact (which can cause a short-circuit, leading to heat), and can explode. If you've seen pictures of exploding laptop batteries, now imagine an explosion with 30 times as many battery cells. It's like some kind of personal Hiroshima.
I know it's not the same, but in Argentina there is a large installed base of Natural Gas-powered cars (close to one million between Argentina and Brazil), with the gas canister at the back, which means a big crash can potentially cause an explosion.

However, accident rates are similar to normal cars. Maybe it's the same with batteries?

See:

http://autos.yahoo.com/green_center-article_114/

http://www.gnc.org.ar/NBC_news.pdf (PDF warning)

http://www.worldenergy.org/wec-geis/publications/d efault/tech_papers/17th_congress/2_3_24.asp

Slight translation needed for the slow

[boyfaceddog]

"demonstrations like this help pave the way for potentially using this technology in small manned and unmanned air vehicles."

That means "weapons", folks.

Re:Slight translation needed for the slow

[ChrisMaple]

Do you consider a recon craft a weapon?

Flying Cars. No thanks.

[Grashnak]

Now if they can come up with a quiet, personal-sized VTOL craft a la Paul Moller's Skycar (which is anything but quiet), we'll really have something." There are at least a half-dozen people in my small town who can't be trusted to drive a car half-way intelligently, let alone fly one. If we could be guaranteed that they would be the only people who would die in their dumb-ass accidents (caused by drunkenness, negligence, or just flat our dumb-assed-ness) then okay, but sadly we can't.

Lack of innovation from companies

[gr8_phk]

There seems to be very little innovation in light plane engines. I'd like to see engines that run on E85 or even even pure stuff. You mention it and people get all bent out of shape about water in their gas, but nobody tries to actually solve the problem - which I hear is not bad at higher alcohol concentrations. They moan if anyone suggests getting the lead out of their precious 100LL too. Oh we need the octane for our dinosaur engines with no electronic controls... BTW E85 has a similar octane rating as 100LL. I'm not a big E85 fan here, but it is one area that's being completely ignored. Another thing I found interesting is the folks putting rotary engines on aircraft - very interesting. I can't believe how resistant the aircraft industry is to change.

How much do you REALLY want the flying car...

[mikeasu]

http://www.youtube.com/watch?v=IsFfBB2W7IA A short written by Kevin Smith for the TOnight Show I think. Or for you anime fans... http://www.youtube.com/watch?v=eBRHetKH4MQ

Nuclear power for large Aircraft

[Danathar]

Although not for short haul flights, a nuclear powered airplane for long flights would be useful. The U.S. Air force and the Russian Air Force both experimented and had plans for nuclear powered bombers as way back as the 50's.

http://en.wikipedia.org/wiki/Nuclear_aircraft

The new AirBus A380 and similar craft (maybe even the old 747) could easily have a small nuclear reactor onboard.

Of course I'm talking purely technical. The politics of flying nuclear powered aircraft over populated areas I'm sure would be quite talk around the water cooler.

well, you are wrong

[way2trivial]

http://www.aviationshop.com.au/atp/cert2aero.htm
Course Content
Core modules are:

Basic Aeronautical knowledge
PPL Ground Training 1 GFPT
PPL Ground Training 2 ... plus
40 hours of flight training

Concerning...

[x1n933k]

Unfortunately the Airline industry is one that hasn't any new technologies that can replace the Jet engine in the event of a fuel crisis. As a student pilot I've watched fuel prices go up and up, but not down (like they do so often with cars). Jet-A isn't in a good situation either. I work for a major airline now as Ground staff--I'm concerned for my co-workers and fellow pilots for the coming years. Investing $50,000.00 to be a commerical pilot now may be a huge mistake regardless of the rebounding airline industry. For people to expect to travel cheap in the next 5 years may find it impossible. To see Boeing looking into alternatives is a sign that at least they're concerned.

[J]

Re:Concerning...

[joto]

Don't worry. When kerosene costs 100x what it does today, they can probably afford to pay their pilots properly.

Boeing SOFC APU

[CompMD]

This is not new territory for Boeing. They've had a solid oxide fuel cell APU in the works for several years, and its doing rather well. I did some aircraft design work involving the integration of the Boeing SOFC APU. As of 2005, the best fuel efficiency is 75%, which when considering a 18,500 BTU/lb heat content of Jet-A, works out to about 0.246 lb/hr/kW. Much better than the 40-45% efficiency than the engine generator can deliver. The worst cruise fuel efficiency for the fuel cell APU was 59%. They want to obtain a 1kg/kW power density for the fuel cell stack and a 0.5kW/kg overall power density for the system by 2015. The stack weight looks achievable, but the system weight is still too high and the lightest weight designed system achieves 0.45 kW/kg.

Sport Aviation or Kitplanes

[Shotgun]

I can't remember which magazine it was that had an article on this in the last issue, but the author ran the number on what it would take to put an electric plane in the air. From his numbers, using current technology, it would be possible, but you'd basically turn a 2-place airplane into a single place, or give up all cargo capacity.

One of the biggest advantages of the ICE is that a large portion of the combustion inputs is not carried by the airplane. The necessary oxygen surrounds the craft, and is pulled in as needed. The battery has to carry all of it's energy inputs all the time.

Re:Flying Cars. No thanks.

[Manhigh]

Flying Cars + GPS + central redundant navigation systems

We'll have flying cars. People just wont be allowed to control them themselves, except for maybe an emergency landing mode.

As a bonus, we could call the central control system 'Skynet'

Airships can travel point to point

[Colin Smith]

If not, what about fuel cell powered dirigibles?

I don't think the problem with dirigibles is how to power them. I think the problem is that there's just about zero demand for a transport service that's about as slow as a ship or train but neither as efficient nor as reliable. Anywhere in the world at 80-90mph There isn't a single other vehicle which even has the potential to do that.

http://www.aerospace-technology.com/projects/cargo lifter/

CargoLifter had several customers lined up who needed large cargos transported direct to site. They ran out of money before completing the prototype airship though.

Hmmm, point to point, anywhere in the world... Almost sounds like a military dream...
http://www.gizmag.com/go/4538/