X Prize Clean Aviation: $10 million

[Altrepair]

Yes for a synchronous AC motor rpm = 120 x frequency / # poles. This motor can not be synchronous. Phrac noted the design is in fact variable frequency.

It also applies to asynchronous motors, but their will be slip obviously when a load is applied so the full load RPM will be less than synchronous. Even a 60HZ motor can have its frequency increased by a variable frequency drive. There is no "design" difference as you state. Some motor manufactures will sale "inverter duty" which the only difference is the motor's insulation is able to withstand the voltage spikes caused by the controller without insulation breakdown.

Anyways I have a feeling you only wrote this because I said I was not going to talk about motor characteristics any longer. You are causing this topic to go off course. If you wish to learn more then either PM or go to the Electrical Engineering forum to post more about electric motors. We need to get back to talking about this X-prize...

 

[mheslep]

Note I started the thread on "X Prize Clean Aviation". A discussion of the power density and / or efficiency of electric motors along with their possible energy sources is extremely relevant in my view.

 

[Altrepair]

Then the alternative would be brushless DC motors which are also cheaper than High temperature super conducting motors. Surely you want to make this clean flying airplane within practical budget. The other benefit is brushless DC motors are also more efficient than asynchronous induction motors.

 

[Phrak]

Anyways, I think we are stirring the topic off course and so I shall refrain from posting about motor characteristics.

Long restatements of common knowledge aren't interesting to read. On topic interests are those you have avoided or misunderstood or don't understand: 1) How does an induction motor scale with frequency? 2) What are the advantages for electric flight, if any, in inducing a magnetic field in a rotor rather than having it supplied for free?

 

[FlexGunship]

2) What are the advantages for electric flight, if any, in inducing a magnetic field in a rotor rather than having it supplied for free?

Asynchronous induction motors traditionally weigh less than synchronous motors with the same power (torque x speed) capability since light weight windings can be made lighter than permanent magnets. Honestly, though, this is only true at very high torque and power values. Probably in excess of 150kW total motive power.

I don't plan to get involved in this discussion, though...

 

[OmCheeto]

Note I started the thread on "X Prize Clean Aviation". A discussion of the power density and / or efficiency of electric motors along with their possible energy sources is extremely relevant in my view.

Agreed.

RonL's spinning battery packs and your SC motor mated in my brain and I ran across something close to the child product:

Brunvoll presents a ”Rim driven thruster” (RDT)

Rather than having the electric motor positioned along the central axis, move it out to the periphery.

I can't imagine a bearing that size being efficient at aircraft speeds, so I would position a conventional core axial bearing support.

Basically, the electric motor and ducted fan become one integral unit.

 

[Altrepair]

OmCheeto, like the idea, and would probably reduce cost even more so.
FlexGunship, I sent that person a PM on what he wanted to know, but what you say is also true.

 

[mheslep]

Updated narrated version of the Puffin VTOL video.
https://www.youtube.com/watch?v=GV0qBU_u3tQ

Summary:

• Blades don't counter rotate, but left and right sides run in opposite directions to counter torque
• On start, trailing edge control surfaces split to deflect thrust, keeping aircraft on the ground until pilot is ready
• Carbon fiber construction for body, provides 300 lb airframe (empty)
• 14' wing span,
• 7' rotors
• cruise 150 mph, sprint 300 mph
• Much quieter than conventional craft due to e-motors
• No turbo charge at high altitude
• Ceiling 30k' feet w/ environmental auxiliaries for pilot
• 50 mile range at cruise w/ 100 lbs of batteries, NASA aiming for 175 miles in 7 years

 

[Cyrus]

50 miles, eek...why not take a car. Even 175 miles is not all that attractive a decade later.

 

[KalamMekhar]

I would prefer something a little more. . . comfortable. As a to and from work device, it seems plausible, but quite frankly traveling long distances in that thing would be absolutely horrible.

 

[mheslep]

50 miles, eek...why not take a car. Even 175 miles is not all that attractive a decade later.

Have fun:

 

[OmCheeto]

I would prefer something a little more. . . comfortable. As a to and from work device, it seems plausible, but quite frankly traveling long distances in that thing would be absolutely horrible.

I'll take a 2 minute uncomfortable flight to work vs a comfortable but maddening 45 minute snail crawl to work any day.

But then, I always was a double black diamond kind of person.

(Emphasis on "was". I'd break a hip if I tried that now.)

 

[RonL]

Have fun:

I would think that is in a foreign country, not America.

 

[Cyrus]

Have fun:

Is this suppose to constutite a valid argument? You don't even know what the average distance those cars in that picture travel and if this vehicle would even begin to address the issue in that photo.

 

[mheslep]

Is this suppose to constutite a valid argument? You don't even know what the average distance those cars in that picture travel and if this vehicle would even begin to address the issue in that photo.

Valid argument? Cyrus, please. My casual response to

50 miles, eek...why not take a car.

Was completely appropriate.

 

[mheslep]

I would think that is in a foreign country, not America.

Oh yes, it's completely different in the US. Texas:
http://www.texasfreeway.com/houston/historic/photos/images/us59_trench_traffic_jam_1962.jpg

 

[RonL]

Oh yes, it's completely different in the US. Texas:
http://www.texasfreeway.com/houston/historic/photos/images/us59_trench_traffic_jam_1962.jpg

Hmmmm, March 1962, I was 19 years old and moved to Houma, La. looks like I made a good choice.
I was living in Houston at that time.

Ron

 

[Cyrus]

Valid argument? Cyrus, please. My casual response to Was completely appropriate.

No, I had a legitimate gripe. 50 miles is what a car is used for, and this is what NASA said this vehicle would not compete against.

 

[Cyrus]

Oh yes, it's completely different in the US. Texas:
http://www.texasfreeway.com/houston/historic/photos/images/us59_trench_traffic_jam_1962.jpg

Again, how far are those cars traveling?

 

[OmCheeto]

Oh yes, it's completely different in the US. Texas:
http://www.texasfreeway.com/houston/historic/photos/images/us59_trench_traffic_jam_1962.jpg

I drove back home from Seattle a few years back on a Sunday afternoon.
The 60 mile stretch to Olympia took me 4 hours.

There was no construction.

There were no accidents.

Just a slew of cars out for a Sunday drive.

I will never drive to Seattle again.

Next time, I'm flying.

And back to the topic:
Those little Schubeler electric ducted fans are only $314 each.(298eur-19%vat)
Generating 20lbs of thrust each, it would only require 8 to lift me off the ground.
Another 8 to lift a smaller Puffin style vehicle.
Another 8 to lift the 160lb battery pack.
That's only $7500 bucks for motors.
100 wh/kg * 73 kg batteries = 7.3 kwh
each fan consumes 7 kw
7*24 fans = 168 kw
7.3 kwh / 168 kw = 2.6 minutes
...

hmmm...

I'll have to do some scaling.




I was coming back from a 3 day regional conference. So no, I was not out for just a Sunday drive.

 

[mheslep]

No, I had a legitimate gripe. 50 miles is what a car is used for, and this is what NASA said this vehicle would not compete against.

Why not? The range is 50 miles in 20 minutes, parking lot to parking lot just like for the car. The car takes an hour, maybe two if you are behind the traffic in one of the photos.

 

[Cyrus]

Why not? The range is 50 miles in 20 minutes, parking lot to parking lot just like for the car. The car takes an hour, maybe two if you are behind the traffic in one of the photos.

Just think about it, having people fly around in an automated highway in the sky "grid" for anything less than 50 miles is a nightmare. All you have done is take the cars and congestion and put it slightly higher in the sky. The airways are already designed for aircraft, so if you are going to suddenly introduce car like airways, they are going to have to be well defined, probably flying overhead existing roads. So you can't just reroute cars anywhere you like it some sort of an optimizer that figure out where to direct each car to minimize travel time for the entire system.

Even for something between 50-400 miles, I don't see why this vehicle works. Take a Cessna, not only is it quick, I can take 4 people along with me.

For more than 400 miles, fly commercial.

 

[mheslep]

Just think about it, having people fly around in an automated highway in the sky "grid" for anything less than 50 miles is a nightmare.

Different topic. You asked why not take a car, not what would happen if all short distance transportation moved into the air.

Even for something between 50-400 miles, I don't see why this vehicle works. Take a Cessna, not only is it quick, I can take 4 people along with me.

Because you can't fly the Cessna out of your back yard. Most people in the US will require at least 40 minutes to get their light traffic airport to reach that Cessna, in which case one might as well drive ( or helo)

 

[Cyrus]

Different topic. You asked why not take a car, not what would happen if all short distance transportation moved into the air.

Because you can't fly the Cessna out of your back yard. Most people in the US will require at least 40 minutes to get their light traffic airport to reach that Cessna, in which case one might as well drive ( or helo)

Watch the video over again, they take off from a heli-port, not peoples back yards, and for good reason. But, let's assume you do fly it from your back yard. This vehicle is a single seater, this is very different from a vehicle you can put more than one person and payload in for an extended range. At that point, you're now talking about larger levels of noise, and inherently large disk loadings. Which means this thing will be shooting rocks and dirt below it at dangerous speeds to people, houses, fences, etc.

The V-22 suffers from this problem too.

-nS-C-xuH-g[/youtube]

 

[mheslep]

Economist article on burgeoning electric aircraft

High voltage
Transport: As electric cars make steady progress on land, battery- powered aircraft of various kinds are quietly taking to the air
http://www.economist.com/node/16295620

 

[mheslep]

Add to that list: Cessna along with Bye Energy are coming out with an electric Cessna Skyhawk 172. Aviation week and mfn sources say the aircraft will

o carry enough batteries on board for two hours of flight,
o have solar panels built into the wings to augment range,
o have a cost per mile flown 'several multiples' cheaper than the same distance flown with aviation fuel.
​

[URL]http://www.byeenergy.com/Pages/assets/images/banners/banner-cessna-iso.jpg[/URL]
http://www.byeenergy.com/Pages/FAQ.html
http://www.cessna.com/NewReleases/New/NewReleaseNum-1192324720455.html

 

[mheslep]

NASA just http://www.nasa.gov/topics/technology/centennial/gfc_final.html" for an (effectively) electric aircraft competition: $1.35 million.

The winning aircraft had to fly 200 miles in less than two hours and use less than one gallon of fuel per occupant, or the equivalent in electricity. The first and second place teams, which were both electric-powered, achieved twice the fuel efficiency requirement of the competition, meaning they flew 200 miles using just over a half-gallon of fuel equivalent per passenger.

Or 400 mpg effective for the winners. By comparison, according to NASA, typical general aviation aircraft achieve 5-50 mpg.Energy per gallon of gasoline is ~34 kWh, so the winners achieved 200 miles/17 kWh. At 150 Wh per kg of Li-ion battery: 113 kg of battery aboard (Edit: reserve of 30 mins required, or +25%; total minimum on board charge/wgt: 21.3 kWh/ 142kg)
More rules:
http://www.nasa.gov/pdf/590567main_NASA Green Flight Challenge_revised.pdf

Performance Required:
Range: 200 statute miles, with 30 min. reserve, day VFR at ≥ 4000’ MSL over nonmountainous, sparsely-populated coastal terrain
Efficiency: ≥ 200 Passenger-MPGe energy equivalency
Speed: ≥ 100 mph average on each of two 200 mile flights
Minimum Speed: ≤ 52 mph in level flight without stall, power and flaps allowed
Takeoff Distance: ≤ 2000 feet from brake release to clear a 50 foot obstacle
Community Noise: ≤ 78 dBA at full power takeoff, measured 250 feet sideways to takeoff brake release
Handling Qualities: Acceptable on all 7 basic handling qualities.

Features Required:
Passengers: Upright seats with adequate volume for a 6-foot tall, 200 pound (lb) adult.
Wingspan: Must fit inside 44-foot wide hangar for weighing (wingfold is acceptable). Height, length and landing gear footprint limits are defined in the Green Flight Challenge Team Agreement.
Vehicle Weights: ≤ 6500 lb. with ≤ 4500 lb. on main gear and ≤ 2000 lb. on nosewheel or tail-wheel
Field of View: Acceptable to FAA licensing authorities and FAA AC25.773-1
Control System: Must provide dual controls if two or more seats
Payload Carried: 200 lbs per seat. Dual pilots if two or more seats. 200 lbs per seat sandbag ballast in all seats not occupied by pilot/co-pilot
Seating Configuration: Tandem seating is allowed, but vehicles with 3 or more seats must place at least 2 seats directly side-by-side. Rapid exit required for all seats.
Fuel/Energy Use: Energy consumed: 1 gallon of 87 octane unleaded auto gasoline = 115,000 BTU. [...]
Fuels/Energy Allowed: Avgas 100 low-lead (LL), Jet-A, diesel, unleaded auto gasoline, bio-fuels, H2, synthetics, electricity.
ePower Measurement: Electric-powered aircraft will use a CAFE-provided power meter to accurately determine energy used during the competition
Flightworthiness: Valid US FAA Airworthiness Certificate for unrestricted day VFR flight in the Continental United States, proof of structural limit

https://www.youtube.com/watch?v=ujeJB8dlie8