Jump to content

A Rather Unique Design :)


Recommended Posts

Hi Everybody

 

I don't know if this new design has made the news in the states yet, or anywhere else for that matter. It was recently featured on a BBC program called "The Dragons Den". Budding entrepreneurs have to try and sell their idea to a panel of five millionaires and convince them to invest their own money to get the business on the road to success. Anyway thats enough of the background, have a look at:-

 

www.kestrelaerospace.com

 

This is (currently only) a single seat VTOL aircraft that runs from 2 electrically powered fan units. I'll spare you all the boring details, which are available on the site.

 

I look forward to seeing all your thoughts/opinions on this unusual twist on aircraft propulsion :)

 

Regards

 

Clive

Link to comment
Share on other sites

Hello All,

 

I did see the program and had a close look at the site. I have emailed Kestrel for more information and also searched to see what i could find out.

 

Kestrel is working in a few new areas and have patents for this new ducted system. They are fitting it to a new high altitude airship in California this week and also seem to be advancing with a new UAV system for commercial & military applications.

 

I will update as i get more information.

 

Regards

 

Simon

Link to comment
Share on other sites

It looks cool, but totally impractical and very dangerous.

 

The rudder would have about zero authority, as it would never be in a clean airstream and it would be of insufficient size. This thing looks to be much less stable than the notably unstable V-22 Osprey, which has had hundreds of millions of dollars thrown at it for control circuitry.

 

Electric fans? This thing will NEVER fly! We have several unmanned hovering vehicles in development here, and the single biggest practical problem is the weight of the motors and batteries that is required to produce the thrust to lift through fan propulsion only. Remember, airplanes are held up by aerodynamic forces on the wings, not by the thrust of the prop. Anyway, all of our electric vehicles are necessarily small, and have very expensive Lithium-polymer batteries if they cary their own power, or are tethered to batteries on the ground. Still, a typical battery charge will only last about 5 minutes when the motors have to produce enough power to lift the vehicle through thrust alone. Very impractical.

 

Cool looking rendering, but do not invest here. I'd be happy to stand corrected, but I doubt that they have any proof-of-concept in actual hardware. This thing looks much better suited as a submarine.

 

-- Len

-- Len Evansic, Cozy Mk. IV Plans #1283

Do you need a Flightline Chair, or other embroidered aviation accessory?

Link to comment
Share on other sites

Hi Len

 

You wrote:-

 

"Electric fans? This thing will NEVER fly! We have several unmanned hovering vehicles in development here, and the single biggest practical problem is the weight of the motors and batteries that is required to produce the thrust to lift through fan propulsion only."

 

I'm probably the least knowledgeable about aircraft in the forum but I think you've missed the point behind the concept on the particular plane.

 

The electric power is supplied by a high performance petrol engine (a Scandinavian made paraglider engine) driving a couple of Permanant Magnet Alternators (PMA's). It is these PMA's that knock out enough electricity to run both fans and any ancillery equipment. Apparently they're hoping to do all this on 5 liters. per hour. Due to the high cost of fuel in UK this is an extremely attractive feature if they can manage it, as unleaded petrol over here is heading towards £4/gallon or $7.20.

 

Although it's difficult for me to say I suspect any port/stbd control would be via the ducted fans turning independently and also the option to vary the output from each fan which would effectively turn the aircraft.

 

Just a thought, anybody else have any idea's.

 

Best Regards

 

Clive ;)

Link to comment
Share on other sites

:o:o:rolleyes::rolleyes:

 

This crock of nonsense is darned close to being a one of those perpetual motion machines.

 

Look, this isn't that hard. It's all about thermodynamics, which summed up goes like this: You can't win the game. You can't break even, and you can't quit. Deal with it.

 

Huge performance at very low fuel consumption isn't going to happen. Period. I dare anyone to PROVE me wrong. Show me one single example of a machine like this that has actually worked. Go ahead. I'll wait.

 

You can do just about anything you want if you throw enough fuel at it. Numerous examples have been produced by the US Air Force. (USAF Law of Aerodynamics: Anything will fly, given enough thrust.)

 

Every engine has a level of efficiency...that is, it takes the energy given to it in the form of fuel, converts a small part of that energy into motion, and wastes the rest as heat. I cannot quote specific numbers unless I put more effort into research than I'm willing to do here, but it's typically very low...way less than 20 percent efficiency. And that doesn't even count transmission losses (e.g., the loss incurred in heating the wire that connects one thing to another in a hybrid fossil fuel/electric system like this one).

 

So you've got an internal combustion engine with its inherent inefficiency driving a generator of some sort with ITS inherent inefficiency, driving an electric motor with ITS inherent inefficiency, which in turn drives a fan with ITS inherent inefficiency. Much commotion, much heat, little useful work.

 

I didn't bother diving very deep into the website, but it looks like the internal combustion powerplant is a small one. Maybe, what, 50 hp? Add up all those losses and I'd be utterly amazed if they get enough thrust at the fans with that absurd driveline to lift the airframe off the ground, much less a pilot.

 

Didn't anyone bother to tell these people that if they hooked the internal combustion engine directly to the fan it would be more efficient and lighter to boot?

 

This thing, to use one of my favorite expressions, is a load of dingo's kidneys.

 

It's remarkably similar to the Moller Aircar, a similarly hare-brained idea that for some reason keeps on appearing on the cover of major magazines (generally either Popular Science or Popular Mechanics) well over a decade after the sexy fiberglass mockup was first constructed. And the idiotic claims are in keeping with the ludicrous design: 400 mph! Anyone can fly it, no pilot's license required! Land it in your driveway and park it in your garage!!!!

 

Oh, PUH-LEEZE.

 

I've seen my mother drive. It's scary. I shudder to think what might happen if a bunch of people like that start carving up the skies in such machines.

 

The Moller Aircar is (or at least was) supposed to have EIGHT Wankel engines in it to lift four people. At least Paul Moller is a bit more realistic about the power requirements needed for VTOL flight than these bozos. What happens when one of those eight engines fails was never explained.

 

It still has not flown. I'll bet a large part of my anatomy that it never will, at least not out of ground effect.

 

Geez, Clive, I would have thought that one of my own clan would have better sense than to even give this thing the time of day.

 

FORWARD!

 

PS: The Scots (Douglas is a Scottish name, for those who don't know) have had a tremendous impact upon world history. Many think this is because there have been a lot of brilliant, inventive Scotsmen, and this may be true...but it's also because the one thing that Scotsmen do best is LEAVE SCOTLAND. :D

======

Not started yet, maybe never will (currently having an affair with an RV project...shhh...don't tell my set of Cozy plans)....

Link to comment
Share on other sites

For some reason the forum isn't letting me edit my message, so here's some more accurate info.

 

The Moller silliness I was referring to is the Moller Skycar, not the Aircar. The specific model is the M400. It has left the ground (proven by photos/video on Moller's website), but has (as far as I can determine) done nothing more than hover a few feet off the ground.

 

I stand by my assertion that machines like this are a giant load of horsehockey. Go buy one, fly it to my house and land it in my back yard. Then we'll talk.

======

Not started yet, maybe never will (currently having an affair with an RV project...shhh...don't tell my set of Cozy plans)....

Link to comment
Share on other sites

The electric power is supplied by a high performance petrol engine (a Scandinavian made paraglider engine) driving a couple of Permanant Magnet Alternators (PMA's). It is these PMA's that knock out enough electricity to run both fans and any ancillery equipment. Apparently they're hoping to do all this on 5 liters. per hour. Due to the high cost of fuel in UK this is an extremely attractive feature if they can manage it, as unleaded petrol over here is heading towards £4/gallon or $7.20.

 

Clive,

 

I didn't see their programme (is that the right U.K. spelling?), but there's not a snowball's chance in hell for this to work enough for them to get off the ground. Adouglas hit on this in his posts, there's just not enough efficiency here to get this off the ground without a bungie from God.

 

Although it's difficult for me to say I suspect any port/stbd control would be via the ducted fans turning independently and also the option to vary the output from each fan which would effectively turn the aircraft.

 

Just a thought, anybody else have any idea's.

In theory, that's probably the only way to justify a single-engine hybrid-electric drive system. In reality, as Adouglas says, it is just way too inefficient all around. Hybrid-electric cars almost make sense because we have gravity and hills, and because in stop and go traffic we spend more than half of the time decelerating. Regenerative braking down hills and slowing the inertia of the vehicle in stop-and-go can be used to generate stored electrical power. This beast is only a power consumer, with no chance of regenerating any power. In this case, a hybrid-electric would consume vastly more energy than a direct-drive internal combustion engine.

 

To match their fuel economy estimates, they would have to use the only extant efficient way of hovering; helicopter rotors, providing lift, not thrust. The difference is that the ducted fan is all about moving a small cross section of air at a high velocity, with blades nearly at stall, where a helicopter rotor works not by forcing the air, but by flying the rotors through it with much less drag.

 

These people learned aerodynamics from animé or video games.

 

-- Len

-- Len Evansic, Cozy Mk. IV Plans #1283

Do you need a Flightline Chair, or other embroidered aviation accessory?

Link to comment
Share on other sites

"Look, this isn't that hard. It's all about thermodynamics, which summed up goes like this: You can't win the game. You can't break even, and you can't quit. Deal with it."

 

That is the best definition I have ever read!! I always thought the many laws of thermodynamics could be summed up and now I have one. Thanks :D

 

By the way, the Air force has two such sayings I guess; Anything will fly, given enough thrust and Give us enough money and we will find that thrust!

 

Ideas like this are probably great intellectual engineering exercises but if they want money, don't look at me.

 

One last thing. If it doesn't have a wing to provide a glide, damn thing better be able to autorotate. Don't believe there is a ducted fan capable of that performance. Could be wrong.

Darrell

Link to comment
Share on other sites

...The Moller Aircar is (or at least was) supposed to have EIGHT Wankel engines in it to lift four people...It still has not flown. I'll bet a large part of my anatomy that it never will, at least not out of ground effect...

Well the prototype has flown. However, I've never seen anyone brave enough to fly it without a tether (it has always been tethered on a crane).

 

Before you really get involved with the powered lift vehicles you really do need to consider how it handles power failures. In the powered lift phase about the only way engine failure is to grab the eject curtain in a big, fat hurry!

 

Another thing to remember is the energy required for lift can crudely be calculated. If you look at the available energy in 5 liters of fuel I daresay you would find it difficult to keep such a creature aloft for more than a few minutes. Throw in efficiency factor into that calculation and you can probably lower that flight time even more.

 

This isn't to say they are being dishonest, or trying to get seed money, but do be careful..

Nathan Gifford

Tickfaw, LA USA

Cozy Mk IV Plans Set 1330

Better still --> Now at CH 9

Link to comment
Share on other sites

Anyway, all of our electric vehicles are necessarily small, and have very expensive Lithium-polymer batteries if they cary their own power, or are tethered to batteries on the ground. Still, a typical battery charge will only last about 5 minutes when the motors have to produce enough power to lift the vehicle through thrust alone. Very impractical.

 

It is not entirely so, actually (not commenting this specific company and its design, but in general), when high amount

of power is required, standard batteries are not the way to go. Actually there are more advanced methods such as hydrogen burning cells etc. The technology is coming to small portable equipment already - one can run a laptop with methanol very much longer than with any conventional battery, the process goes so that part of the methanol is converted to hydrogen and the cell converts the hydrogen to electricity. That is the way of the electric cars of the future as well, conventional batteries have their limits and they are not suitable everywhere.

 

I do not comment ducted fan VTOL designs, but in general,

I think an airplane engine could be replaced with electric engine if there would be hydrogen cells of sufficient power on board (expensive, but not necessarily so heavy). The hydrogen cell causes quite much zero pollution and is very efficient and with a brushless electric motor it would be extremely reliable).

 

We have two electric cars in our household and they are using

those conventional batteries, no hydrogen cars in our household yet, someday, potentially yes.

Link to comment
Share on other sites

I think an airplane engine could be replaced with electric engine if there would be hydrogen cells of sufficient power on board (expensive, but not necessarily so heavy).

That would depend entirely on what I believe is called the energy density of the system. A tank of gasoline (petrol) has a LOT of energy packed into a small amount of fuel...high energy density, therefore a lot of energy available to lift the aircraft without having to lift a lot of fuel (and associated components).

 

The basic problem with electric propulsion for aircraft is that the energy density of the system simply is not great enough for actual flight. The exception is the high-altitude electric flying wing built by NASA, but it draws power from solar panels that cover the entire upper surface of the wing (IIRC the wing span is over 100 feet and the thing's payload is considerably less than the mass of a human...but I may be wrong about that).

 

The example you cited of a fuel-cell powered laptop is not applicable and is a bit misleading, because you only cited weight and endurance, not size. Build a fuel cell with associated methanol tank the same size as a laptop battery and I seriously doubt it would run as long as current battery technology. Also, laptop batteries don't have to produce much current. Running a high-output electric motor is a whole different ball game.

======

Not started yet, maybe never will (currently having an affair with an RV project...shhh...don't tell my set of Cozy plans)....

Link to comment
Share on other sites

There are other problems using hydrogen, principally storage. Hydrogen is very bulky and difficult to store. While it does not weigh anything like methanol or other fuels it takes a lot more volume to get the same energy release.

 

The other problem with clean burning hydrogen is where you get it. The dirty secret about hydrogen is that it is not extracted from seawater, its extracted from oil. If you want to extract it from seawater, you can do that too but it takes one of those things called a fission reactor (fusion later). Then you have the problem of transporting the hydrogen which is nowhere near as easy as propane.

 

None of these are insurmountable tasks. However, it will take a long time to build the infrastructure that will allow for the safe handling and transport of hydrogen by common, everyday people.

Nathan Gifford

Tickfaw, LA USA

Cozy Mk IV Plans Set 1330

Better still --> Now at CH 9

Link to comment
Share on other sites

I think you are missing the point. This team is not really trying to do a Rutan to vertical flight, they are trying to con capital out of 5 millionaires to further their project. SOMETHING that will revolutionise SOMETHING by doing something AMAZING may appeal to the cigar chomping drones with the farcical hair-dos than something practical and achievable.

 

For example, look at the life & times of the Orbital Engine company. When I was a kid there were constant articles about Ralph in the Australian newspapers & motoring magazines. The pitch was always the orbital engine (like a rotary, but different) which would eclipse all other methods of burning petrol. It drove, it floated & it flew, as a prototype. But they never sold a single engine. Eventually they sold something (not the orbital engine) which almost made it into the Ford Ka but now only seems to have application in two stroke motors.

 

But all that is beside the point, coz Ralph was rich, rich, richie rich long before they SOLD ANYTHING.

 

Go, go Kestrel. And if all they have to show for it in 20 years is dirigible propulsion and vast personal fortunes GOOD ON 'EM.

Mark Spedding - Spodman
Darraweit Guim - Australia
Cozy IV #1331 -  Chapter 09
www.mykitlog.com/Spodman
www.sites.google.com/site/thespodplane/the-spodplane

Link to comment
Share on other sites

If you want to extract it from seawater, you can do that too but it takes one of those things called a fission reactor

There are other sources of electricity out there:

- wind energy

- vastly of unused potential available

- solar power

- geothermic energy

etc.

 

Besides that, the energy density is not everything, but also

the efficiency. Fuel cells win in efficiency against any piston

engine (efficiency of a fuel cell is between 45-60% whereas on

piston engine it is between in comparison TE of Lycosaur IO-540-K is 27.9% and on TIO-540-V2AD TE is less than 20%).

 

The energy contents per kg on hydrogen is 39 kWh/kg.

For gasoline, the same number is 12 kWh/kg.

 

If you disagree, I think you should join NASA and suggest them replacing their fuel cells in their equipment with gasoline generators which burn gasoline and oxygen instead.

Link to comment
Share on other sites

There are other sources of electricity out there:

- wind energy

- vastly of unused potential available

- solar power

- geothermic energy

etc.

 

What this fails to take into account is the total amount of power required to run the infrastructure (you need to consume electricity to produce the hydrogen, plus electricity to pressurize or liquefy it, and possibly to refrigerate it... and there are inefficiencies in that process), but let's assume you can get enough electricity from thes sources to make it work...the big issue is the COST of doing it. Things would be rosy indeed if we could afford to implement all of this stuff. Just because it's possible doesn't make it a good idea when ALL factors are considered.

 

There are wind farms in California that are falling into disrepair because they cost too much to run...they're simply not economically viable yet.

 

Besides that, the energy density is not everything, but also

the efficiency. Fuel cells win in efficiency against any piston

engine (efficiency of a fuel cell is between 45-60% whereas on

piston engine it is between in comparison TE of Lycosaur IO-540-K is 27.9% and on TIO-540-V2AD TE is less than 20%).

 

The energy contents per kg on hydrogen is 39 kWh/kg.

For gasoline, the same number is 12 kWh/kg.

 

This is misleading. Energy per kilogram is not the relevant measure. Energy per liter is. The energy density of hydrogen per liter is very, very low, regardless of its state (gas or liquid). This is the fundamental problem with using hydrogen as a fuel in the real world.

 

To carry enough hydrogen in an airplane to fly any significant distance, you'd have to liquefy it. Which means that you'd have to carry a large, heavy refrigeration unit capable of outstanding performance that would most likely wipe out the payload of the airplane. Road vehicles using straight hydrogen fuel have concentrated on high pressure vessels carrying gaseous hydrogen, but the range of these vehicles is a small fraction of that possible with a gasoline-powered vehicle...because the hydrogen my have high energy density per KILOGRAM, but very, very low energy density PER LITER, especially in gaseous form. Liquid hydrogen is still much less dense than gasoline, so the energy density per liter is less.

 

All you need for a gasoline vehicle is an uninsulated tank that holds the fuel at ambient temperature and pressure. And you can carry less fuel because of the greater energy density per liter.

 

Note that the most practical fuel cell vehicles in development are those that extract their hydrogen from gasoline. One reason for this is the opressive requirements for storage of hydrogen fuel. The bigger reason is the infrastructure question.

 

If you disagree, I think you should join NASA and suggest them replacing their fuel cells in their equipment with gasoline generators which burn gasoline and oxygen instead.

Oh, really, now. Don't be silly. NASA does not use fuel cells because they're more efficient. NASA doesn't give a fig about internal efficiency. They use fuel cells because the byproducts are useful (heat, water and electricity), not because they're inherently superior in any other way. When you can produce water as a byproduct of producing electricity, it's a win-win...you don't have to lift the water out of the earth's gravity well in the first place.

 

In a space vehicle the critical concern is not energy efficiency, it's weight...and EVERYTHING that gets consumed (except solar radiation) needs to be carried. If the total weight of an electricity-producing system consisting of a gasoline-fueled internal combustion engine, a generator, fuel, oxygen to run the engine, water to make up for that not produced by fuel cells and all the associated tankage and plumbing were less than the total weight of a fuel cell system producing the same amount of electricity and providing an equivalent amount of water, then you'd better believe that NASA would be using it instead. NASA will try to use anything that gets the job done for the least weight, no matter what it is.

 

Ever wonder why the manned vehicles don't use solar panels? Because when the TOTAL system is considered, the fuel cell solution makes more sense, even though it's less fuel-efficent (after all, a solar panel has infinite fuel efficency because there's no fuel, right?).

 

Efficiency is only part of the equation, and hydrogen is not the be-all end-all.

 

If you disagree, then go join NASA and ask them why the first stage of the Saturn V was fueled with kerosene instead of hydrogen. :P

======

Not started yet, maybe never will (currently having an affair with an RV project...shhh...don't tell my set of Cozy plans)....

Link to comment
Share on other sites

Fuel cells do have a lot of advantages and Karoliina is correct that the methanol fuel cells produce more power than their battery cousins (and have a longer useful life since they don't work by oxidation/reduction).

 

The whole idea of clean hydrogen never has considered how you make it and transport it. While hydrogen has more power per kilogram, it takes a lot more volume of hydrogen to the same fossil fuels needs.

 

There have been attempts to use photovoltaics to extract hydrogen, and wind farms, etc can be used to do the same but these do offer thus far the capacity needed to make vast quantities of H2. Certain types of fission reactors can be used to generate these quantities, but then the problem of transport remains (ie can current pipeline technology be safely used to at three time the current pressure).

 

I would love to see fuel cell technology succeed. This will happen and it will happen in our lifetimes (well I guess that depends on your current health!!). Hydrogen transmission is still up in the air in my book since some basic physics have to be applied. Other energy technologies may beat hydrogen to the market place (fusion, room temp superconductors) first.

Nathan Gifford

Tickfaw, LA USA

Cozy Mk IV Plans Set 1330

Better still --> Now at CH 9

Link to comment
Share on other sites

  • 2 years later...

Fuel cells do have a lot of advantages and Karoliina is correct that the methanol fuel cells produce more power than their battery cousins (and have a longer useful life since they don't work by oxidation/reduction).

 

The whole idea of clean hydrogen never has considered how you make it and transport it. While hydrogen has more power per kilogram, it takes a lot more volume of hydrogen to the same fossil fuels needs.

 

There have been attempts to use photovoltaics to extract hydrogen, and wind farms, etc can be used to do the same but these do offer thus far the capacity needed to make vast quantities of H2. Certain types of fission reactors can be used to generate these quantities, but then the problem of transport remains (ie can current pipeline technology be safely used to at three time the current pressure).

 

I would love to see fuel cell technology succeed. This will happen and it will happen in our lifetimes (well I guess that depends on your current health!!). Hydrogen transmission is still up in the air in my book since some basic physics have to be applied. Other energy technologies may beat hydrogen to the market place (fusion, room temp superconductors) first.

a solar powered blimp does the trick just fine
Link to comment
Share on other sites

when petrol engines first came out we didn't have the infrastructure did we?

Funny thing that. When Henry Ford started to mass produce cars, the fuel of choice was alcahol. Rockefeller lobbied to make the national standard based on petroleum (hence the birth of Standard Oil.)

T Mann - Loooong-EZ/20B Infinity R/G Chpts 18

Velocity/RG N951TM

Mann's Airplane Factory

We add rocket's to everything!

4, 5, 6, 7, 8. 9, 10, 14, 19, 20 Done

Link to comment
Share on other sites

There's one thing that's been overlooked here.

 

Hydrogen is currently not a viable energy source. It is best thought of as a storage medium of energy, like a battery.

 

The reason why that is so is because currently it cost more in term of energy to make the hydrogen than can ever be recovered from the hydrogen, even assuming 100% efficiency.

 

This may change in the future, but that's the state of the art right now.

WileEZ

"All of my ideas are suspect until proven otherwise!"

Link to comment
Share on other sites

There's one thing that's been overlooked here.

 

Hydrogen is currently not a viable energy source. It is best thought of as a storage medium of energy, like a battery.

 

The reason why that is so is because currently it cost more in term of energy to make the hydrogen than can ever be recovered from the hydrogen, even assuming 100% efficiency.

 

This may change in the future, but that's the state of the art right now.

I guess what we are waiting for here is for the alchemists to figure out a way

break the oxygen and hydrogen atoms contained in water??? Do this.....earth is covered by 2/3rd's in fuel potential

Link to comment
Share on other sites

I guess what we are waiting for here is for the alchemists to figure out a way

break the oxygen and hydrogen atoms contained in water??? Do this.....earth is covered by 2/3rd's in fuel potential

You don't need alchemy to do that. All you need is a battery. Still not an efficient process.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information