Personal tilt-rotor

[TangoWhiskey]

This is on the cover of Popular Science this month:

http://www.falxair.com

Innovative design; uses a 100hp engine at 2-4gph to power generators for two electric engines, batteries store the extra "oomph" required for takeoff. Batteries with enough storage/discharge rates are not yet available for VTOL capability, but they anticipate they will be, soon.

The spec sheet showed an optimistic 170 mph cruise and 270 mph top speed. Oh, and a $1M+ price tag. So "personal" depends on the size of your checkbook.

 

[vontresc]

Looks neat, but to me it looks like someone had fun playing with solid works. I'd love to see something like this finally move out of the vaporware/popular mechanics stage, but I am not holding my breath.

 

[Ken Ibold]

I love reading PopSci, but indeed, 99.9 percent of the contents is vaporware. Still, a guy can dream!

 

[Falxair]

Looks neat, but to me it looks like someone had fun playing with solid works. I'd love to see something like this finally move out of the vaporware/popular mechanics stage, but I am not holding my breath.

Gentlemen, Just to let you know, Pop Sci has made a few minor errors in the article and also some additions we did not even know about ourselves.

Mainly, the expected price is incorrect. It happens to be a lot lower.

The platform is a real design, over eight years of research, testing and development of materials, engines and the very latest energy storage tech. Yes we still have certain issues to over come, one being the full certification of the motor controllers (a big barrier to jump) but we are trying our hardest to take this project into a fully functional platform.

I am afraid i cant tell you too much about the hybrid system as we are still filling patents on certain processes and internal components.

I hope this clears a few things up and I will attempt to update on our progress as time goes on.

 

[steingar]

Good luck. I hope it all works out for you.

 

[Henning]

This is on the cover of Popular Science this month:

http://www.falxair.com/main.htm

Innovative design; uses a 100hp engine at 2-4gph to power generators for two electric engines, batteries store the extra "oomph" required for takeoff. Batteries with enough storage/discharge rates are not yet available for VTOL capability, but they anticipate they will be, soon.

The spec sheet showed an optimistic 170 mph cruise and 270 mph top speed. Oh, and a $1M+ price tag. So "personal" depends on the size of your checkbook.

It's cute, but with no shaft tying the rotors, it'll take a pretty good chunk of money to get me to fly it.

 

[Henning]

Gentlemen, Just to let you know, Pop Sci has made a few minor errors in the article and also some additions we did not even know about ourselves.

Mainly, the expected price is incorrect. It happens to be a lot lower.

The platform is a real design, over eight years of research, testing and development of materials, engines and the very latest energy storage tech. Yes we still have certain issues to over come, one being the full certification of the motor controllers (a big barrier to jump) but we are trying our hardest to take this project into a fully functional platform.

I am afraid i cant tell you too much about the hybrid system as we are still filling patents on certain processes and internal components.

I hope this clears a few things up and I will attempt to update on our progress as time goes on.

When one side goes "kaput" what keeps you under control? There is a reason that all the other tilt rotors have a cross shaft and gear boxes.

 

[Anthony]

Would a small turbine engine driving a E motor be an efficient way of powering an aircraft once storage battery and turbine tech catch up to the requirement. Is this an efficient way to transfer energy? I believe diesel locomotives and some submarines do this.

 

[Henning]

Would a small turbine engine driving a E motor be an efficient way of powering an aircraft once storage battery and turbine tech catch up to the requirement. Is this an efficient way to transfer energy? I believe diesel locomotives and some submarines do this.

There are many diesel/turbine electric drive applications, most all of them gain an advantage from the extra weight.

 

[Anthony]

There are many diesel/turbine electric drive applications, most all of them gain an advantage from the extra weight.

Would a lightened system be feasible in a small aircraft, fixed or rotor?

 

[Henning]

Would a lightened system be feasible in a small aircraft, fixed or rotor?

I'm having trouble seeing it Turbine+transmission+shafts+gears+Prop/rotors, or Turbine +Gearbox+Generator+cables+batteries+motor controls+electric motors+props/rotors. The only potential way I see making weight is by using very high voltage drives, 12,000volts or so, and even then, there is nothing linking the rotors to prevent assymetric upset. I love the tilt rotor concept, and I think this machine is pretty cool in shape, but it has too much potential for going horribly wrong for me to like the propulsion method.

 

[Falxair]

When one side goes "kaput" what keeps you under control? There is a reason that all the other tilt rotors have a cross shaft and gear boxes.

Thats correct, they use two engines cross shafted for safety.

Lets just say each nacelle contains more than one electric motor, each one of the multiple motors (if they fail) does not effect the others. Each propulsion unit is monitored and adjustments are automatically made to the prop pitch ensure safety, likewise we use several power cables for each motor, yet again, for added safety.

We have both onboard power generation and energy storage system, if one fails, the other can take over to ensure a controlled, safe landing. If everything fails (which is not likely) we fit a BRS as standard.

 

[Henning]

Thats correct, they use two engines cross shafted for safety.

Lets just say each nacelle contains more than one electric motor, each one of the multiple motors (if they fail) does not effect the others. Each propulsion unit is monitored and adjustments are automatically made to the prop pitch ensure safety, likewise we use several power cables for each motor, yet again, for added safety.

We have both onboard power generation and energy storage system, if one fails, the other can take over to ensure a controlled, safe landing. If everything fails (which is not likely) we fit a BRS as standard.

Interesting, when/where is the prototype? What voltage are you operating at?

 

[Falxair]

Interesting, when/where is the prototype? What voltage are you operating at?

We currently have all major components bench tested and assembley of the flight test platforms (three of them) will hopefully be complete by Christmas (crossing every finger i have).

As mentioned before, I will upload info as we start flight testing and post images of the assembley work when we have chance.

Lets say the voltage is well above 350v.

 

[TangoWhiskey]

Wow, Falx Air found this post quickly! Is Google that good? Nice to have the designer/builder here talking about it. How do you pronounce your business name? It looks like it would be "False Air"...

By the way, I'd love to see one of your prototypes fly to our annual gathering at Gaston's.

 

[Anthony]

It looks like it would be "False Air"...

Or maybe "Faux Air".

Just kidding. Nice to have you here.

 

[TangoWhiskey]

Or maybe "Faux Air".

Just kidding. Nice to have you here.

Maybe it's "falcs", like "falcons".

 

[Falxair]

Maybe it's "falcs", like "falcons".

yes thats right, ''Falx' is a Latin word originally meaning sickle, but was later used to mean any of a number of tools that had a curved blade that was sharp on the inside edge such as a scythe. The word is also ssociated with certain birds of prey due to the sickle shaped leading edge of the wings when diving or at high speed.

 

[gismo]

We have both onboard power generation and energy storage system, if one fails, the other can take over to ensure a controlled, safe landing. If everything fails (which is not likely) we fit a BRS as standard.

JOOC, how would a BRS help if a motor failed during landing or takeoff when you're high enough to cause injury (>20 ft) but too low for the parachute to deploy in time to help)?

Much of the concept seems feasible but I have to say that a 170 mph cruise and a 270 mph top speed on 100 HP sounds wildly optimistic and casts doubt on the rest. Was that something PopSci dreamed up or your own marketing hype?

 

[Falxair]

JOOC, how would a BRS help if a motor failed during landing or takeoff when you're high enough to cause injury (>20 ft) but too low for the parachute to deploy in time to help)?

Much of the concept seems feasible but I have to say that a 170 mph cruise and a 270 mph top speed on 100 HP sounds wildly optimistic and casts doubt on the rest. Was that something PopSci dreamed up or your own marketing hype?

The platform design shown in PopSci is just that, a design, while we are making headway towards a fully flight ready POC we are making many changes to both the aerodynamics and structure to ensure safety. this includes landing gear that can take a heavy impact from low altitude, heavy impact seating frame etc.... the main thing with going for the hybrid is that it is more robust than a drive shaft/gearbox/turbine solution.

The system contains two parts, a battery system and an onboard genset. The genset delivers more than 100+hp and the battery system adds another 110hp, when both power systems deliver maximum power we do have a higher max speed. Now this is limited because of the energy available from the battery system, so MAX speed cannot be sustained for long, but in a "get the hell out of here" situation it is more than enough.

Cruise has a dual setting, "Economy" and "Power", the first runs purley off the main genset while "Power" runs genset and a small amount of energy from the battery pack, this then gives us an hour of power cruise before we need to throttle back to "Economy" (still leaving enough energy for an emergancy landing if needed).

Look guys, we dont have ALL the answers yet and I am 110% sure we will hit many issues as we progress but I believe its possible and we are trying to make it reality, if you feel our ideas suck, then so be it, but we are still going to give it our best efforts.

 

[TangoWhiskey]

in a "get the hell out of here" situation it is more than enough.

Cool... will you call that "Vh"? ;-)

I think what you're working on is awesome. I've spent some time talking to folks that are working on new designs--the solving of the problems/puzzles it presents is half the fun. Sure beats a desk job! Good luck!

 

[Teller1900]

Look guys, we dont have ALL the answers yet and I am 110% sure we will hit many issues as we progress but I believe its possible and we are trying to make it reality, if you feel our ideas suck, then so be it, but we are still going to give it our best efforts.

I think I can speak for most everyone here when I say I don't think your idea sucks at all! A lot of these guys are the over-thinking engineer types (*ducking*), and we're all the curious type, so finding out as many details as possible is what we do. I know I certainly appreciate your candor and willingness to share in your creative process. And I really look forward to some pictures when things start coming together!

 

[gismo]

The system contains two parts, a battery system and an onboard genset. The genset delivers more than 100+hp and the battery system adds another 110hp, when both power systems deliver maximum power we do have a higher max speed. Now this is limited because of the energy available from the battery system, so MAX speed cannot be sustained for long, but in a "get the hell out of here" situation it is more than enough.

Cruise has a dual setting, "Economy" and "Power", the first runs purley off the main genset while "Power" runs genset and a small amount of energy from the battery pack, this then gives us an hour of power cruise before we need to throttle back to "Economy" (still leaving enough energy for an emergancy landing if needed).

Look guys, we dont have ALL the answers yet and I am 110% sure we will hit many issues as we progress but I believe its possible and we are trying to make it reality, if you feel our ideas suck, then so be it, but we are still going to give it our best efforts.

Hey, I wasn't saying you should give up, just that (as is typical with a PopSci article IME) the chances are extremely high that the picture painted in the article is, shall we say, "a bit rose colored". I think a low end tilt rotor would be really cool, even if it could only go 140 mph on 100 HP. I also believe that an "out of the box" approach to the design like your electic motor/ICE hybrid is worth pursuing although I suspect you will eventually realize that current battery technology coupled with aviation's need for very conservative life limits (that would likely mandate battery replacement way too often to be affordable) will eliminate any possible advantage of electrical energy storage. I also think you'll find that the weight and cost of the battery will easily exceed the weight/cost of an ICE with the additional power capacity. And even if the cost/weight issue favored a battery, you'd need to assume that the battery's charge would have to be replaced during flight, not depleted further by using that energy to extend the aircraft's range or speed since there will be no provision to recharge it on the ground in most cases.

But by all means, keep at it. I'd love to see you suceed.

 

[TheMonk]

Make it work sans the tilt feature and you sell plenty. Use that profit to fund the tilt R&D.

Monk

 

[docmirror]

Yep, this is a study in energy density. Ya got yer batts, and yer motors, and yer engines, and yer generators, and coupling, and control systems. Lotsa mass there. so, we use the motors plus the gen to get it up and hover, and into translational lift. Ya prolly got maybe less than a minute of time to get off the ground and get the wing providing a significant amount of lift before yer out of battery, or the motors overheat from excess load, or both.

Here's some stuff you're gonna find(or already have). It's too heavy out of ground effect. You're gonna get some really ugly gyroscopic effects(it's not just the props, ya know) tilting the rotors. Cross rotor boundary effect is divergent(this is a killer).

I think eventually this will get cute little wheels and it'll turn into a jump take off system, not VTOL. Which is ok, still looks cool. dump the five blade prop, it's super inefficient, and weighs more. Even the big boys only use three. Maybe gonna need a longer empenage, get a bit more moment-arm back there, it's hard to tell though, don't have my slide rule handy.

Have fun!

 

[Falxair]

Yep, this is a study in energy density. Ya got yer batts, and yer motors, and yer engines, and yer generators, and coupling, and control systems. Lotsa mass there. so, we use the motors plus the gen to get it up and hover, and into translational lift. Ya prolly got maybe less than a minute of time to get off the ground and get the wing providing a significant amount of lift before yer out of battery, or the motors overheat from excess load, or both.

Here's some stuff you're gonna find(or already have). It's too heavy out of ground effect. You're gonna get some really ugly gyroscopic effects(it's not just the props, ya know) tilting the rotors. Cross rotor boundary effect is divergent(this is a killer).

I think eventually this will get cute little wheels and it'll turn into a jump take off system, not VTOL. Which is ok, still looks cool. dump the five blade prop, it's super inefficient, and weighs more. Even the big boys only use three. Maybe gonna need a longer empenage, get a bit more moment-arm back there, it's hard to tell though, don't have my slide rule handy.

Have fun!

Ok, I have a question to ask you all if you dont mind?

Which is better, a Tilt-Rotor, a Tilt-Wing or a Tilt-Duct?

We have been working with two very switched on aerodynamics guys and also some structural engineers and they are looking at past work done with the DOAK 16 (VZ-4). We know of some new patented control technology that would be very good at utalising the tilt-duct system. Your thoughts would be great.

 

[jason]

Wow, Falx Air found this post quickly! Is Google that good? Nice to have the designer/builder here talking about it. How do you pronounce your business name? It looks like it would be "False Air"...

By the way, I'd love to see one of your prototypes fly to our annual gathering at Gaston's.

I imagine that he was watching his analytics (referrer) reports after the article.

 

[KennyFlys]

Ok, I have a question to ask you all if you dont mind?

Which is better, a Tilt-Rotor, a Tilt-Wing or a Tilt-Duct?

We have been working with two very switched on aerodynamics guys and also some structural engineers and they are looking at past work done with the DOAK 16 (VZ-4). We know of some new patented control technology that would be very good at utalising the tilt-duct system. Your thoughts would be great.

First, I'd like to know the answer to the following:

Is there a difference between each method for directional control when in gusting winds? What will provide the most thrust and quick change in direction of thrust to move above obstacles more quickly or at least with the most stability?

Also, what about the amount of power it would require for the initial vertical takeoff and vertical landing? What percentage of available fuel/energy is left for normal use as well as an emergency reserve? VTOL is very rarely done with the Harrier because of the fuel it burns.

 

[docmirror]

Ok, I have a question to ask you all if you dont mind?

Which is better, a Tilt-Rotor, a Tilt-Wing or a Tilt-Duct?

We have been working with two very switched on aerodynamics guys and also some structural engineers and they are looking at past work done with the DOAK 16 (VZ-4). We know of some new patented control technology that would be very good at utalising the tilt-duct system. Your thoughts would be great.

Oye, I don't know anything about a tilt-duct setup, sorry. I would think the articulating centre-pivot would maybe lend itself by design to tilt-wing. Tilt-rotor individually is gonna be a real hard one to control. Yep, I think I'd articulate the wing, then use a centering V-guide and roller to get the wing lined up as it moves into wing configuration. Just a guess, has benefits and costs like the other systems, but keeping the articulation in the fuselage fixes a lot of logistics problems out on the wing/rotor area.

 

[Falxair]

Oye, I don't know anything about a tilt-duct setup, sorry. I would think the articulating centre-pivot would maybe lend itself by design to tilt-wing. Tilt-rotor individually is gonna be a real hard one to control. Yep, I think I'd articulate the wing, then use a centering V-guide and roller to get the wing lined up as it moves into wing configuration. Just a guess, has benefits and costs like the other systems, but keeping the articulation in the fuselage fixes a lot of logistics problems out on the wing/rotor area.

Sorry for the late response Docmirror,

Things are moving quickly here and changes happening daily. I was working with a new design of control tech from Canada for nearly two years, supporting them and helping push the tech, Im glad to say we have managed to intergrate the system into our new, two seat design that will lower our footprint by half and also increase our safety.

The new OAT tech developed in Canada has been scaled from small RC prototype systems at 15% scale to a 40% scale version that we filmed last year when spent time in the UK with us. The plan is now to build the 100% scale platform here for flight testing before we release a final pre-production version at the end of next year.

Lots of people have emailed regarding the platforms and to answer those who have asked, yes we will be producing a kit but not until 2010.

Thanks to all that have shown a great deal of support for our work so far and we will continue to push as hard as we can.

Thanks all, Falxair

 

[john smith]

I want to see some weight & balance numbers. How many batteries are in the tail boom to offset the 500 lbs forward of the main spar (structure + pilot & pax)?
What it the projected gross weight?
How many pounds of thrust are required to aircraft? How many pounds of thrust will each engine produce?
Again, cross-shafting to prevent asymetric thrust is essential.
Tilt-wing structure weight vice tilt-rotor structure weight?

 

[Falxair]

I want to see some weight & balance numbers. How many batteries are in the tail boom to offset the 500 lbs forward of the main spar (structure + pilot & pax)?
What it the projected gross weight?
How many pounds of thrust are required to aircraft? How many pounds of thrust will each engine produce?
Again, cross-shafting to prevent asymetric thrust is essential.
Tilt-wing structure weight vice tilt-rotor structure weight?

Dear John Smith,

Batteries and Genset are built into the tail section to offset the forward weight. The battery package is linked to the rear seat sensor that adjusts the position of the pack to change the CofG depending on the load carried, more information on this balance system im afriad i cannot divulge.

Fuel for the gen-set is stored in a certified fuel tank directly under CofG.

Length: 168"
Width: 132"
Height: 72"

Battery: 180 cells
Battery Weight: 90kg (inc BMS)
Genset Weight: 97kg

Empty Weight:387kg
MAX TO Weight: 638kg

The propulsion system is proprietary but produces over 380kg of static thrust per nacelle. New blade optimisation work is ongoing and we are looking closley at a US company that is producing over 8lbs of static thrust per hp compared to the 7.2 lbs of static thrust per hp we currently develope using our 120hp nacelle. If testing goes well we will employ the new blade profiles and produce over 430kg per nacelle (1892+lbs).

I hope this helps

Falx Air

 

[Henning]

Battery: 180 cells

396 VDC? Wow..... 90 Kw per side...that's 227 amps. You need a 200 Kw generator, where are you finding a generator that light that puts out 200Kw? Heck, even 90kw. You'll have to go turbine to get anywhere near light enough. Then the motor sets you're looking at... What are you using for cabling? I'm having a real hard time picturing a 387kg light ship weight if you have 90kg for the batteries that leaves 297kg or 653lbs for everything else. That's pretty damned light for 240hp.

 

[Falxair]

396 VDC? Wow..... 90 Kw per side...that's 227 amps. You need a 200 Kw generator, where are you finding a generator that light that puts out 200Kw? Heck, even 90kw. You'll have to go turbine to get anywhere near light enough. Then the motor sets you're looking at... What are you using for cabling? I'm having a real hard time picturing a 387kg light ship weight if you have 90kg for the batteries that leaves 297kg or 653lbs for everything else. That's pretty damned light for 240hp.

Airframe is made from new NANO-Fibre composites, 40% lighter than normal composites with slightly more strength.

I'safraid we cannot release the supplier of the generator for commercial reasons but lets just say it produces just under half of the energy required for VTOL, the rest comes from the batteries.

The main genset is used all the time, it supplies more energy than is required for cruise and the extra energy produced is put back into the battery pack. When you need to take-off or land vertically, we combine the energy from the genset and batteries to produce what is required. Hover endurance is the limiting factor as we cannot hover for long periods.

Remeber the Doak VZ-4, it could transition from Vertical Take-off to forward flight in 20sec.

Regards

 

[Henning]

Airframe is made from new NANO-Fibre composites, 40% lighter than normal composites with slightly more strength.

I'safraid we cannot release the supplier of the generator for commercial reasons but lets just say it produces just under half of the energy required for VTOL, the rest comes from the batteries.

The main genset is used all the time, it supplies more energy than is required for cruise and the extra energy produced is put back into the battery pack. When you need to take-off or land vertically, we combine the energy from the genset and batteries to produce what is required. Hover endurance is the limiting factor as we cannot hover for long periods.

Remeber the Doak VZ-4, it could transition from Vertical Take-off to forward flight in 20sec.

Regards

That's what I was figuring, hence my 90Kw comment for the genset, I still think you're gonna have a heck of a time making that weight. Good luck, I hope to be flying one in a couple of years.

 

[Falxair]

That's what I was figuring, hence my 90Kw comment for the genset, I still think you're gonna have a heck of a time making that weight. Good luck, I hope to be flying one in a couple of years.

Thanks Henning,

We are working with two great structural engineers that have built somevery lightweight platforms in the past so hopefully the combination of the knowledge they have and the new materials will do the job jus fine.

Regards

Falx Air

 

[Henning]

Thanks Henning,

We are working with two great structural engineers that have built somevery lightweight platforms in the past so hopefully the combination of the knowledge they have and the new materials will do the job jus fine.

Regards

Falx Air

My concern is that I have also worked with some brilliant structural engineers who designed, and we built, ultralightweight structures in the boat (both sail and power) and auto racing industries, and I was eerily correct on predicting the catastrophic failures we encountered. I have worked in Australia building small aircraft, and I know how quickly they get "fat" when you start adding all the gov't required safety items and the comfort features the consumer demands. If you are just looking at the military market, you can get away from the fluff, problem is you have to design even further for "off design axis" shocks and loads, and it takes meat to do it, and the weight of the meat adds up quickly. From what I have read of the nanofiber technologies, they have high monoaxial strength in tension, but not so great in the sheer which necessitates additional layups in off axis biases to make strength for off axis impacts. I remember when we took Double Bullet II out for her first sail, she had one of the first carbon fiber masts. We hit Hurricane Gulch in LA Harbor and I looked up and the mast was pumping like a piece of wet spaghetti. I told him "That's gonna break" "Nah, the engineers said it's supposed to do that" "Maybe, but it's not going to tollerate it for long." On the delivery back from Acapulco after setting the record, the mast exploded off Turtle Bay. Like I said, good luck, I'd love to be flying one.

 

[Falxair]

My concern is that I have also worked with some brilliant structural engineers who designed, and we built, ultralightweight structures in the boat (both sail and power) and auto racing industries, and I was eerily correct on predicting the catastrophic failures we encountered. I have worked in Australia building small aircraft, and I know how quickly they get "fat" when you start adding all the gov't required safety items and the comfort features the consumer demands. If you are just looking at the military market, you can get away from the fluff, problem is you have to design even further for "off design axis" shocks and loads, and it takes meat to do it, and the weight of the meat adds up quickly. From what I have read of the nanofiber technologies, they have high monoaxial strength in tension, but not so great in the sheer which necessitates additional layups in off axis biases to make strength for off axis impacts. I remember when we took Double Bullet II out for her first sail, she had one of the first carbon fiber masts. We hit Hurricane Gulch in LA Harbor and I looked up and the mast was pumping like a piece of wet spaghetti. I told him "That's gonna break" "Nah, the engineers said it's supposed to do that" "Maybe, but it's not going to tollerate it for long." On the delivery back from Acapulco after setting the record, the mast exploded off Turtle Bay. Like I said, good luck, I'd love to be flying one.

Hi Henning,

Yes you are right regarding the nano-fibre in some respects, but the newer batches of materials being developed in Ohio and Stuttgart are very much improved when compared to early batches, I believe both EADS and BAE Systems are testing the newer batches on some very lightweight structures for long endurance UAV platforms and I have also been told that it is also finding its way into the new, lightweight X35 to allow it to shed a few extra pounds.

We will be doing this the easy way, by building a 100% scale testbed that is capable of lifting a single person, then moving onto the dual seat as we progress with flight testing. I know its baby steps but we have to ensure its done right first time, personally id rather carry an extra few pounds of airframe to ensure its safe than take the risk.

Regards

 

[Henning]

Hi Henning,

Yes you are right regarding the nano-fibre in some respects, but the newer batches of materials being developed in Ohio and Stuttgart are very much improved when compared to early batches, I believe both EADS and BAE Systems are testing the newer batches on some very lightweight structures for long endurance UAV platforms and I have also been told that it is also finding its way into the new, lightweight X35 to allow it to shed a few extra pounds.

We will be doing this the easy way, by building a 100% scale testbed that is capable of lifting a single person, then moving onto the dual seat as we progress with flight testing. I know its baby steps but we have to ensure its done right first time, personally id rather carry an extra few pounds of airframe to ensure its safe than take the risk.

Regards

As I said, best of luck and I truly wish you success. I'd love to come over and check your project out.

 

[Dan Thomas]

396 VDC? Wow..... 90 Kw per side...that's 227 amps. You need a 200 Kw generator, where are you finding a generator that light that puts out 200Kw? Heck, even 90kw. You'll have to go turbine to get anywhere near light enough. Then the motor sets you're looking at... What are you using for cabling? I'm having a real hard time picturing a 387kg light ship weight if you have 90kg for the batteries that leaves 297kg or 653lbs for everything else. That's pretty damned light for 240hp.

I'm trying to see where he said 90 Kw per side, but in any case, 200 Kw divided by 746 watts per horsepower is 268 hp. ANd that's ignoring efficiency losses. If it has a 100 hp engine it won't go far. And any 100 hp engine that produces that power at 2-4 GPH is a marvellous engine that we need to drive propellers with. Normally, a 100 HP engine is going to burn about .4 lb/hp/hr, at least, and that works out to 40 lb/hr which is 6.7 GPH, at best.

I'm 55 years old and spent many years reading PopSci and Popular Mechanix and so forth, and as I got older and read repeatedly of fantastic new machines that never, ever made it to market, I got a little cynical. I've seen dozens of new engine designs, helicopters, airplanes, VTOL machines and the like, yet we're still using the same old piston engine in our cars that we were using the the '50s, just with fancier fuel and spark delivery systems. We're still flying airplanes designed in the '50s (and earlier, though the composites made a big difference) and there isn't a helicopter in every driveway. And Mr. Moller has been fleecing the innocent for decades now and continues to do so.

Forgive me for wanting to see a flying prototype before I believe anything more I see in the "science" magazines.

Dan