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By Robert Rapier on Mar 5, 2011 with 48 responses

Electric Aviation is the Future of Transport

During an average week, I will see a few ideas that at first glance appear to be a little crazy. On second glance, some of them still seem crazy, but then some of the seemingly crazy ideas are not as crazy as I initially thought. This essay is about an idea that falls into the latter category. I have long-believed that the future of aviation will still be liquid fuels due to the low energy density of batteries. While I am aware of ultra-light electric or solar-powered planes, it is hard for me to imagine a passenger plane being operated on electricity.

This essay is about a hybrid version of electric aviation that gets around my concerns about electric planes by only using electricity during takeoff. It is a revolutionary idea, and the author is looking for some constructive feedback from readers. So if you have thoughts on why it might work, might not work, or might work with certain modifications, feel free to weigh in with your comments.

The essay was written by John Carpinelli, who is an electrical/software engineer based in the San Francisco Bay area (his brief bio follows his essay). You can read more about this idea at his website Electric Take-Off or contact him at john “at” electrictakeoff.com.

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Electric Aviation is the Future of Transport

By John Carpinelli

In the 2011 State of the Union speech, President Obama described the development of clean energy and transport technologies as the Apollo projects of our time. It was disappointing that Obama’s speech did not mention clean aviation. Electric aviation can replace our oil-based transport with a system that is faster, cleaner and cheaper using existing technology. No advanced batteries are required to build this system!

In 2008, NASA funded several teams to design aircraft with 70 percent lower fuel consumption and a 71-decibel reduction below current FAA noise standards. The teams were led by General Electric, M.I.T., Northrop Grumman and The Boeing Company. The Boeing team designed a hybrid electric aircraft to reduce noise and fuel consumption. The team’s report concluded that hybrid electric engine technology “is a clear winner, because it can potentially improve performance relative to all of the NASA goals.” The major limitation of electric aircraft continues to be the weight and cost of batteries. Current electric aircraft have low payloads and speeds due to limited battery power. The Chinese company, Yuneec, demonstrated its E430 electric aircraft in 2009. The single-seat aircraft flies with lithium batteries for up to three hours with a maximum take-off weight of 1034 lb. The light sport aircraft is promising, but has a maximum speed of just 150 km/h.

In the 1950′s, the missionary pilot Nate Saint pioneered the use of circular flights for retrieving payloads from the ground using fixed wing aircraft. A bucket trailing the aircraft on a cable was lowered to the ground and kept stationary by flying in a circle. After the payload had been transferred to the bucket, the aircraft would revert to straight flight and the payload would ascend on the cable. Modern pilots have demonstrated the technique which can be viewed online.

Electric Take-Off

An electric takeoff system can be built using the same principle for much greater payloads. Electric tow planes would circle a hub at an existing airport with one rotation every two minutes. Payload aircraft would attach to a winch cable at the hub using a three-point harness. The winch motors in the hub would immediately tow the payload to altitude with acceleration similar to an electric elevator. The take-off would be silent and smooth for the passengers.

At the top of the winch cable, the payload aircraft would be travelling as fast as the tow planes and with an altitude of 30,000 feet or more. The harness could be detached when the aircraft is travelling in the desired direction. For higher altitudes including suborbital flights, the payload would detach from the winch and continue along the extended cable using centripetal force. As the cable travels in a circle, the payload would be accelerated towards the outside of the cable. To avoid drag, the cable would fly at high altitudes using its own lift. Centripetal force would cause longer cables to extend outside the atmosphere due to the curvature of the Earth.

Any new transportation system should be evaluated on the key criteria of economics, market and safety. Basic economic modeling shows that the electric take-off system would be cheaper than conventional aviation and trucking for freight. Electric power prices are generally lower and more stable than oil prices. For a typical aircraft, electric take-off and climb would be complete in less than three minutes compared to fifteen minutes for a conventional take-off. A Boeing 737 consumes about 5000 lb of jet fuel in an average takeoff and climb to cruise altitude. That fuel cost is $2000 at current jet fuel prices compared to a projected $650 for an electric take-off. There is a strong business case for airports and airlines to deploy the technology to reduce their consumption of jet fuel.

Electric Take-Off Design

The global aviation industry spends approximately $200 billion on aviation fuel based on current prices. A significant fraction of that fuel is spent on taxi, take-off and climb as they are the least fuel-efficient phases of any flight. By retrofitting aircraft for electric take-off assist, much of this fuel cost could be saved. In addition, cheap electric air freight would capture market share from the trucking industry thanks to lower fuel costs. The trucking industry is estimated to contribute 5% of America’s GDP. The development of electric take-off would be motivated by fuel cost savings in the aviation sector and it could potentially replace a large share of America’s freight industry with electric transport.

Take-off is the most expensive and dangerous phases of any flight. An engine failure in the first minute of flight gives the pilots little time to respond. Electric take-off has the potential to be safer than conventional aviation through the use of reliable electric motors and redundant tow planes. In the event of a power failure, the electric tow planes could be landed at the airport under battery power. The winch cable could be fitted with parachutes at regular intervals to be deployed in case of a broken cable. Residents living near airports should welcome the electric system as it will eliminate aircraft take-off noise. The tow planes will fly at high altitude and will not be audible from the ground.

The electric take-off system has the potential to be safe, economical and to capture a large share of the aviation market. The system hub would be constructed adjacent to existing airport runways. The tow planes would take-off and land under electric power in the same way as normal aircraft. The airspace around existing airports is tightly controlled by the FAA and airport authorities. Air traffic controllers should be able to schedule landings to avoid the short period when the cable will overfly the runway. Overall airport capacity will be increased as take-offs will no longer require use of the runway.

Cheap access to space and suborbital flight would be a simple extension of the infrastructure. As suborbital vehicles become available, they could be launched by extending the length of existing cables used for aviation. The cables can be constructed from commercially available HMPE fiber that is currently used in the oil and gas industry. Lift would be generated by the tow aircraft flying in circles and the cable would be shaped like a wing to generate additional lift as it travelled through the air. A 1000km cable could accelerate the payload to a speed of 8 km/s at the tip which would allow suborbital flight and the potential to reach low Earth orbit. For suborbital flights, the system would be much cleaner, safer and quieter than a rocket launch. The design is discussed in a 2009 book by Michel Van Pelt titled “Space Tethers and Space Elevators“.

President Obama has called for Apollo projects to deliver clean energy transportation to America. Electric aviation can deliver cheap, clean transport for passengers and cargo without the political controversies of high-speed rail. There is a strong business case for airlines and airports to deploy the electric take-off system to reduce fuel costs. The system could reduce aviation’s dependence on expensive oil and capture freight market share from the trucking industry. The aviation industry should take the lead in developing and deploying this clean transport technology.

Biography

John Carpinelli is Vice President of a software company based in the San Francisco bay area. During his fifteen year professional career, he has delivered major software projects for companies in the aviation, oil and electricity sectors. He started his career as a software engineer at the world’s largest mining company, BHP Billiton. He holds degrees in electrical engineering and computer science from the University of Melbourne, Australia.

  1. By Wendell Mercantile on March 5, 2011 at 8:08 pm

    Navy aircraft carriers use steam pistons, but modern technology better to go with linear motors.

    The newest Navy carrier now under construction and to be launched ~2015, the USS Gerald R. Ford (CVN-78) will have catapults with linear indiction motors instead of using steam.

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  2. By drunyon on March 5, 2011 at 8:08 pm

    With any wind blowing during tow the aircraft would not be stable for passenger comfort. With significant weather (thunderstorms, etc) wind would hit the long cable at different velocities which would also cause stability issues. As winds change (at altitude or lower level), controlling the tow aircraft to maintain the end of the cable on the runway would be quite challenging. A gust (near ground or at tow altitude) or downdraft to the tow aircraft as the passenger plane is lifting off the runway would likely be catastrophic since there is no effective lift on the passenger plane wing to make corrections. Converting all electrical power generation to fission seems much safer.

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  3. By Wendell Mercantile on March 5, 2011 at 8:30 pm

    Tow the aircraft to high altitude (e.g. 35,000 feet) using electricity from the grid.

    John,

    It dose sound attractive with respect to energy use, but there are practical problems to overcome. Not impossible, but they would be major hurdles.

    The system would not be compatible with the present air traffic control system. A cable going up to FL 300 and describing an inverted cone with a base 8 km wide, would tie up large blocks of airspace that other aircraft couldn’t use. There may be places in the country where that would be acceptable, but not around our major air transportation hubs.

    The aircraft releases from tow and glides towards the destination for 100 – 200 miles using no fuel.

    Gliding the last 100-200 miles would present another problem for air traffic control — they would have no flexibility for maneuvering the airplane as it glided in. It would a need to be deconflicted in a straight-shot all the way down the glide until touchdown. The only airplane/spacecraft now that glides in to a landing is the space shuttle, and air traffic control has to restrict the airspace and keep all other aircraft out of the reentry corridor. That has been easy to do for the 3-4 times a year the space shuttle flew, but there would be problems integrating that mode of operation into our airspace structure with the frequency you suggest.

    The airline’s insurance companies also may have a problem with an unpowered airplane that glides into a landing. What if the runway is blocked or fouled after the airplane commits itself to the approach? How would it go around?

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  4. By Bill on March 5, 2011 at 12:46 pm

    Probably crazy, but….

    There is some precedent in launching aircraft by ground based power. It’s called “winch launch” and is commonly used to launch gliders. (Search YouTube for “winch launch” or the German word ‘windenstart’)

    During the last desperate days of WWII, German engineers experimented with winch launching bombers too heavily loaded with fuel and bombs to take off on their own. Heights achieved equal about half the runway length. Hypothetically, cargo aircraft might be launched with electric winches resulting in some savings in fuel and/or with heavier payloads.

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  5. By Kit P on March 5, 2011 at 3:14 pm

    This is not an electric powered airplane. Misleading to the point of lying but BOEING targeted the gullible. This is why engineers should stick their field of expertise so they do not look like idiots. Writing soft ware for the power industry, is not the same as power engineering. In the same way being a chemical process engineer is not the same as power engineering.

     

    First let me explain hybrids like the Pious. They are not electric cars. The are powered an ICE. Adding batteries in theory allows them theoretically to operate in a more efficient part of ICE operating curve. It depends on how you drive. Just like buying a muscle car does not make you a NASCAR driver. For those who not know it, car dealers sell image more than reality. To be blunt it is called lying.

     

    If hauling batteries down the road is your idea of being ‘green’, you have issues. It is still just a POV with a ICE.

     

    Will adding batteries to the gas turbine ICE of an airplane make it electric driven? No! Will it use less liquid jet fuel? I am a little skeptical of that too after reading the BS that BOEING wrote:

     

    “Moreover, the fuel burn reduction and the ‘greening’ of the electrical power grid can produce large reductions in emissions of life cycle CO2 and nitrous oxide.”

     

    Everyone wants to take credit for greening of the grid. At the rate everyone is taking credit, we should be sucking ghg out of the air by burning fossil fuels.

     

    “However, Bradley said, in order for the hybrid electric concept to be competitive, battery technology “needs to improve many, many times over what we have today.”

     

    Oh, is that all. I have a practical plan too. When pigs fly, I will put AD to turn poop into electricity to to make fly pigs go faster.

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  6. By Benny BND Cole on March 5, 2011 at 3:32 pm

    Fascinating ideas.
    BTW, I have heard that some engineers believe we could have large solar collectors in orbit that would send electricity down to earth by microwave transmission (similar to cars charging up by parking over the wireless transmitters.

    How about large solar collectors that beam down electricity–and that it received by electric airplanes?

    I know it is a wild idea, but you would not have that cumbersome tether.

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  7. By tim randle on March 5, 2011 at 3:53 pm

    entirely too complicated and risky for American aviation.

    if you want to use electricity for take off, just have the aircraft brought up to speed using a longer runway by a magnetically coupled, electrically powered two bar. that’s fuel that would never have to be transported (or even held) by the aircraft to begin with–imagine being able to take off with your tanks completely full!

    the navy is perfecting this techonology for their next aircraft carrier right now–just slow it down and use it for the next generation of cargo aircraft, then migrate it to passenger aircraft. too easy.

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  8. By Forrest on March 5, 2011 at 3:56 pm

    The winch tow, makes sense to me. High speed train research should be valuable. Navy aircraft carriers use steam pistons, but modern technology better to go with linear motors. Acceleration could be controlled for smooth take off and landings. Maybe regenerative braking? The high energy zone within critical safety would be optimized with electronic communication interlocks i.e. the airport controller would energize takeoff granted for pilot activation. Just the typical industrial safety logic for machinery. Acceleration could be constant avoiding jerk and achieve high mph for quick climb rate. Probably upon a shorter runway. Also, with this technology it becomes safe to utilize 100% the length of runway. These linear motors used for ultra high speed positioning of most accurate CNC metal machining, .001 inch to electronics is like 600 yds for a pilot.

    Aircraft waste fuel at tarmac level. Those jet engines inefficient for low speed maneuvering of plane. Rail or tow system could, instead, do the work with engines off. Better to put the navigation under control of airport computer to maximize coordination and communication. Under computer control gates utilization should jump making it practicable to schedule passengers per open gates throughout terminal, meaning no dedicated gate required. May this be the smartest use of high speed rail fed money? Something of higher value to the majority that doesn’t try to reinvent our current excellent high speed aircraft transportation system. Never understood why it was safer to be bombed in a train or bus as compared to aircraft? Would think terrorist enjoy a one way cruise? Didn’t we have to make Federal workers out of airport security workforce? Thus the fairy dust of central power can be bestowed upon them keeping us safe. Better hire them likewise for trains, cruse ships, and buses.

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  9. By John Carpinelli on March 5, 2011 at 4:43 pm

    To summarize the design:

    1. Tow the aircraft to high altitude (e.g. 35,000 feet) using electricity from the grid.
    2. The aircraft releases from tow and glides towards the destination for 100 – 200 miles using no fuel.
    3. The aircraft lands at an intermediate airport for another tow.  Repeat steps 1 and 2 until the destination is reached.

    The result is cheap electric air freight or passenger travel without fossil fuels or advanced batteries.  For longer hops, longer cables can be deployed for higher altitudes and speeds.

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  10. By walter-sobchak on March 5, 2011 at 5:15 pm

    What kind of problem is Mr. Carpinelli trying to solve?

    And what kind of unobatinium are those cables made out of? How much do they weigh? What happens when a cable breaks?

    What is the thermodynamic efficiency of turbo fan engines? Is it much different from electrical generators?

    What is the likelihood that I will be able to persuade my wife to get on one of those things.

    Is this the answer to a question that anybody has asked.

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  11. By John Carpinelli on March 5, 2011 at 5:30 pm

    Walter Sobchak said:

    What kind of problem is Mr. Carpinelli trying to solve?

    And what kind of unobatinium are those cables made out of? How much do they weigh? What happens when a cable breaks?

    What is the thermodynamic efficiency of turbo fan engines? Is it much different from electrical generators?

    What is the likelihood that I will be able to persuade my wife to get on one of those things.

    Is this the answer to a question that anybody has asked.


    Walter,

    The problem is expensive, imported oil that is required for aviation currently.

    The cables are made out of commercially available HMPE fiber.  Google “Samson Ropes Neutron 8″ for the example used in the economic model.  The cables weigh 43 metric tons in my example design.

    The electric engines flying at low speeds should be more efficient.  See this Wikipedia article for details: http://en.wikipedia.org/wiki/J…..n_of_types

    The design is potentially safer than conventional aviation for reasons listed in the essay.

    The aviation industry seems to be focused on biofuels as the future solution.  Electric takeoff is an alternative approach that has great potential in my opinion.

    There are more details on the electrictakeoff.com web-site.

    John

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  12. By John Carpinelli on March 5, 2011 at 9:27 pm

    drunyon said:

    With any wind blowing during tow the aircraft would not be stable for passenger comfort. With significant weather (thunderstorms, etc) wind would hit the long cable at different velocities which would also cause stability issues. As winds change (at altitude or lower level), controlling the tow aircraft to maintain the end of the cable on the runway would be quite challenging. A gust (near ground or at tow altitude) or downdraft to the tow aircraft as the passenger plane is lifting off the runway would likely be catastrophic since there is no effective lift on the passenger plane wing to make corrections. Converting all electrical power generation to fission seems much safer.

    The cable is attached to a ground hub which should weigh more than 200 ton and be bolted to the ground.  The upward force from the tow plane should keep the cable tension at 100 ton or higher to support the pulley.  The cable tension should keep it stable aganst variable winds.  Multiple tow planes could be deployed to smooth the variations in lift also.
     

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  13. By John Carpinelli on March 5, 2011 at 9:34 pm

    Wendell Mercantile said:

    Gliding the last 100-200 miles would present another problem for air traffic control — they would have no flexibility for maneuvering the airplane as it glided in. It would a need to be deconflicted in a straight-shot all the way down the glide until touchdown. 

    The airline’s insurance companies also may have a problem with an unpowered airplane that glides into a landing. What if the runway is blocked or fouled after the airplane commits itself to the approach? How would it go around?

    In the short term, aircraft can use jet fuel for maneuvering, landing and go-around.  The amount of fuel required for descent and landing should be relatively low.  In future aircraft, batteries could be used to power the descent and landing phase.  Existing battery technologies are good enough for this purpose.

    With regard to insurance, I completely agree that the aircraft must have engine power available for a go around.

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  14. By John Carpinelli on March 5, 2011 at 9:58 pm

    With regard to air traffic control, the next generation system from the FAA should help with the transition.  The industry is moving towards continuous descent approach to save fuel already.  The hub airports are constrained by runway space and this system would remove departing aircraft from the runways.

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  15. By Kit P on March 5, 2011 at 11:19 pm

    “unobatinium”

     

    That’s funny Walter.

     

    “The problem is expensive, imported oil that is required for aviation currently.”

     

    John, oil is a cheap commodity. Maybe not as cheap as it used to be. Second, the reason people fly is to save time. Everybody is in a hurry. As long as you are traveling on planet earth, it takes a lot more power to go faster. This is the fundamental problem with BEV too. If people were content to travel at 15 mph golf carts and sail boats would be used for more than recreation.

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  16. By walter-sobchak on March 6, 2011 at 12:41 am

    John Carpinelli said:

    The problem is expensive, imported oil that is required for aviation currently.

    Jet Fuel is less than 10% of the total usage of petroleum. My guess is that it is the highest valued use, and the likely the last to be economically limited. Fuel is less than a quarter of airline expenses. Of course obsoleting all of the airline’s existing capital won’t help them financially. 

    The cables are made out of commercially available HMPE fiber.  Google “Samson Ropes Neutron 8″ for the example used in the economic model.  The cables weigh 43 metric tons in my example design.

    When one of those things breaks, it will be a catastrophe. I can easily imagine one taking a line of cars on the airport entrance road and punting it it into LEO. Yes, I saw the line about parachutes on the cable. But, parachutes don’t fail safe.

    I cannot see that this type of operation would be acceptable near any urban area. The nearest airport to me (CMH) is a mere 3 mi. from the center of the main to my house in a straight line. Most airports that serve major urban centers have been centers of growth for many years and have large populations around them. Not to mention older, but still absolutely vital airports like LGA, DCA, and MDW. I would think that you would need a clear radius around your airport equal to your cable length. Finding parcels that size near major urban centers will be very difficult, and very expensive.

    The electric engines flying at low speeds should be more efficient.  See this Wikipedia article for details: http://en.wikipedia.org/wiki/J…..n_of_types

    The comparison needs to be end to end. My guess is that a turbofan or turboprop engine is operating close to its Carnot limit of thermal efficiency. A fixed gas turbine that is part of a combined cycle generation plant is also highly efficient, but by the time you pump the electricity out to the end of the line and run it through the motor, you have lost something. Of course in your system, the orbiting lifter will not be turning all of its energy into work, because it will have to cycle between launches, and because there will be friction and heat loss.

    The design is potentially safer than conventional aviation for reasons listed in the essay.

    I am not seeing it. Gliders are cool, but flying them in less than perfect weather is really scary. In mid-summer, thunderstorms can pop-up here in the mid section of the country any time without warning. AF 447… Part 3

    The aviation industry seems to be focused on bio-fuels as the future solution.  Electric takeoff is an alternative approach that has great potential in my opinion.

    Bio-fuels are not a paneca. I am starting to think that corn-ethanol is close to a war crime. But, hydrocarbons can readily be synthesized, even if your only raw materials are air and water.

    There are lots of other issues with your system. The up down up down is not attractive and would add lots of time to a trip. Right now with TSA and all of the other crap of flying in the 21st century, trips of less than 500 mi. are often faster by car than by airplane.

    Another problem is the limited range of your system. I don’t need to fly to get to places that can be driven to in an afternoon. I need to fly to go to California which is 2000 mi from here. Your system would take a lot of hops from here to CA, enough so that weather and other delays become a real problem.

    Of course trips across oceans are not accounted for at all.

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  17. By Wendell Mercantile on March 6, 2011 at 10:06 pm

    Cables overflying neighbourhoods shouldn’t be any more dangerous than conventional aircraft takeoff.

    Of course unless the cable shears and ~30,000 ft of cable fall down on the neighbors around the airport. Have you asked any the government who do zoning what issues they would have with 30,000 of cable being dragged through a cone high in the sky above the neighbors of the airport? For construction of tall television tower, zoning usually requires a set back of at least 75% and sometimes 100% of the height. A 75% set back applied to your scheme would mean no houses within 22,500 ft (4.26 statute miles) of the cable anchor point. (That might be possible in eastern Montana or Wyoming’s Red Desert.)

    Even though you present an efficient way to use energy, the long pole in the tent will be liability issues. Have you asked any insurance companies to give an estimate of what it would cost to cover such an enterprise?

    Moeity pointed out a very real problem with wind shear (differences in direction and speed) from the surface up to FL 300. Have you done any research into the experience with tethered barrage balloons in WW II? They were always breaking loose, and they only went up a few hundred feet into the air to deter low-flying aircraft.

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  18. By John Carpinelli on March 6, 2011 at 1:58 am

    This design should reduce noise for residents living near airports.  Cables overflying neighbourhoods shouldn’t be any more dangerous than conventional aircraft takeoff.  At ground level, the cable is moving very slowly.  It completes a revolution every two minutes.  

     

    The 200 mile hop is a compromise to support the current fleet of aircraft and would mainly be used for freight and short haul flights.  Passenger flights travelling 2000 miles could burn jet fuel for the cruise phase to make the journey in one leg.  Future aircraft could be designed for higher glide ratios, higher altitudes and greater speeds to enable longer hops without fuel.

     

    If you are a long haul passenger, the biggest potential benefit of the system is cheap supersonic and suborbital flight.  The cable would be extended beyond the tow plane for 200 miles or longer.  The tip of the cable would be travelling at high altitudes and mach numbers.  When your aircraft reached the end of the cable, you could be flying at the edge of space and potentially complete the journey from Ohio to California in an hour.  Even longer cables could enable trans-continental travel.  Of course, a new fleet of aircraft would be needed to support suborbital flights, but it is theoretically possible.

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  19. By moiety on March 6, 2011 at 7:15 am

    John Carpinelli said:

    drunyon said:

    With any wind blowing during tow the aircraft would not be stable for passenger comfort. With significant weather (thunderstorms, etc) wind would hit the long cable at different velocities which would also cause stability issues. As winds change (at altitude or lower level), controlling the tow aircraft to maintain the end of the cable on the runway would be quite challenging. A gust (near ground or at tow altitude) or downdraft to the tow aircraft as the passenger plane is lifting off the runway would likely be catastrophic since there is no effective lift on the passenger plane wing to make corrections. Converting all electrical power generation to fission seems much safer.

    The cable is attached to a ground hub which should weigh more than 200 ton and be bolted to the ground.  The upward force from the tow plane should keep the cable tension at 100 ton or higher to support the pulley.  The cable tension should keep it stable aganst variable winds.  Multiple tow planes could be deployed to smooth the variations in lift also.
     

     

    THe problem is wind speed at different elevations would put extreme stress on the cable as it would be pushed and torqued potentially at multiple elevations and in different directions. Further I doubt a 200 tonne weight would be enough unless we a talking about very light aircraft.

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  20. By russ on March 6, 2011 at 2:29 pm

    This belongs in the comic section.

    The unobtanium is probably more practical.

    The 200 ton block is a bit of a joke – no more than a bit – it is a very big joke.

     

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  21. By robert on March 6, 2011 at 5:51 pm

    A former boss made an electric airplane but it was more E430 than transportation. Single seater, glider body packed with lithium batteries.

    A gasoline engine is rated at it’s maximum horsepower. An electric motor is rated at its most efficient power output. You can overdrive the motor on takeoff as long as nothing smokes or melts and you keep an eye on your battery charge level. Level flight uses a lot less power than takeoff.

    It’s one of the few applications you can drive the propeller directly from the motor without a gearbox. The propeller and the motor turn at a couple thousand rpm.

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  22. By thomas398 on March 6, 2011 at 5:57 pm

    Benny BND Cole said:

    Fascinating ideas.
    BTW, I have heard that some engineers believe we could have large solar collectors in orbit that would send electricity down to earth by microwave transmission (similar to cars charging up by parking over the wireless transmitters.

    How about large solar collectors that beam down electricity–and that it received by electric airplanes?

    I know it is a wild idea, but you would not have that cumbersome tether.


     

     
    Benny,

    Space based solar power (SBSP) is an “end game” future power source that could provide large amounts of ”renewable” base load power.  Its advantages over conventional solar are that a satellite in space could be exposed to sunlight  almost 24/7 and that sunlight would be many times more intense and unaffected by terrestrial weather.   The physics of transmitting microwaves is pretty inflexible however, requiring that any transmission over long distances result in a wide,diffuse beam.  Transmissions from space would require a rectifying antenna on the ground of several kilometers in radius or more practically thousands of small rectennas spread out over the same area.  Even at the beam’s center the radiation levels are not expected to be above OSHA work level standards. http://en.wikipedia.org/wiki/S…..olar_power

     

    This diffuse energy “drizzle” from orbit seems to better suited for stationary power plants rather than rapidly moving planes.   Transmission via laser is another option but there is the whole issue of keeping the target and the beam aligned.  

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  23. By walter-sobchak on March 6, 2011 at 11:21 pm

    I have given up. I am not an engineer, and trying to figure this thing out has gone beyond the limit of my retained knowledge of math and physics.

     

    My sense is that the proposal presents real challenges in terms of the engineering that are not fully acounted for. In particular the proposal needs to address the masses, forces, velocities, and accelerations involved. I have a hard time believing that the parameters given can be done with the technology mentioned.

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  24. By moiety on March 7, 2011 at 3:07 am

    Walter Sobchak said:

    I have given up. I am not an engineer, and trying to figure this thing out has gone beyond the limit of my retained knowledge of math and physics.

     

    My sense is that the proposal presents real challenges in terms of the engineering that are not fully acounted for. In particular the proposal needs to address the masses, forces, velocities, and accelerations involved. I have a hard time believing that the parameters given can be done with the technology mentioned.


     

    You could assume that the thing is a cantilever. Hell to be really generous you could assume that it is supported at two ends and see what the stresses are in the middle depending on the support loads at either end.

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  25. By Benny BND Cole on March 7, 2011 at 12:52 pm

    Thomas 398-Thanks for your post, I enjoyed it. I remain fascinated by the idea of transmitting energy via microwave or laser beams. I am sorry that airplanes won’t be able to use microwave power.

    I still harbor hopes that busses or cars could be re-powered by microwave while commuting. Certainly busses, that stop at regular intervals in set places, could be repowered on their routes by microwave. Charging up a flywheel? That’s my other favorite power source that always seems just out of practical commercial reach.

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  26. By rrapier on March 7, 2011 at 1:07 pm

    Benny BND Cole said:

    Fascinating ideas.

    BTW, I have heard that some engineers believe we could have large solar collectors in orbit that would send electricity down to earth by microwave transmission (similar to cars charging up by parking over the wireless transmitters.


     

    I know someone who worked on this problem in the past. He said he got an unfriendly visit from someone in the government – CIA maybe, I forget – because a system like that could be used as a weapon. They were afraid of this being developed and our enemies getting a hold of it.

    RR

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  27. By doggydogworld on March 7, 2011 at 1:31 pm

    A few comments:

    1. Although it may take 15 minutes for a commercial airplane to climb to cruise altitude, the plane covers quite a bit of ground (almost 100 miles) during those 15 minutes. It’s not as if the 3 minute winch climb presented here saves 12 minutes of travel time.

    2. Similarly, a big chunk of the fuel burned during climb is goes to cover horizontal distance. Winch climb only saves a portion of that fuel. I’d guess it’s less than 5% of typical flight fuel burn.

    3. A 3 minute winch climb to 35k ft implies vertical speeds in excess of 150 mph for the main part of the climb, kind of mind-boggling.

    4. The cable with 100 ton tension is analagous to a violin string, with all kinds of resonant frequencies and harmonics. Static load handling is one thing, dynamic damping quite another.

    5. As mentioned, this scheme consumes a huge chunk of airspace for 20 takeoffs per hour. Busy airports like ATL are rated for over 100 takeoffs per hour.

    I really don’t get the winch up/glide for 100 miles/land/winch up again model. Even if only used for cargo, is it meaningfully faster than truck or rail? Optimal airliner glide speed is less than typical cruise speed and is really slow at low altitude. Add in the time wasted landing and waiting in line for the next winch up and overall trip time increases dramatically. More to the point, if the plane is not a pure glider but requires an engine or motor for aborted landing go-rounds, why even bother with the electric plane circling at 35k ft? Just have the glider climb to altitude with its own motor and a really long extension cord which it releases before gliding to the next airport.

    FWIW, I think 100 mile glides might be doable but 200 miles is beyond the capability of today’s planes. And since they’re highly engineered for good lift/drag ratios I doubt new designs would offer dramatic improvements.

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  28. By Nicolas Depardieu on March 7, 2011 at 9:07 pm

    I am sorry but this is a very very very bad idea.

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  29. By thomas398 on March 8, 2011 at 12:41 am

    Benny BND Cole said:

    Thomas 398-Thanks for your post, I enjoyed it. I remain fascinated by the idea of transmitting energy via microwave or laser beams. I am sorry that airplanes won’t be able to use microwave power.

    I still harbor hopes that busses or cars could be re-powered by microwave while commuting. Certainly busses, that stop at regular intervals in set places, could be repowered on their routes by microwave. Charging up a flywheel? That’s my other favorite power source that always seems just out of practical commercial reach.

    Benny, we should be spending at least as much on SBSP as we do on plasma fusion.  We’ve thrown tens of billions at fusion over half a century, and at the summit of each technical challenge lay yet another mountain range. The primary challenge to SBSP is not technical but economic—lowering the $/kg cost of reaching orbit. Solving that problem will have a long list of secondary economic benefits.  The U.S. military has to see that this could free it from powering remote bases with diesel generators.  Generators that have to be fueled by long and dangerous supply lines.  Having 50 MW that you can point anywhere in the world is a game changer even it costs you $50 billion to put in place.
     

    On the civilian side one could see wireless transmitters fitted to freeway streetlamps charging BEVs passing below.   There are probably lots of non transportation related applications where wireless energy will be most useful.

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  30. By Frank on March 8, 2011 at 1:17 am

    What sort of acceleration does the plane experience from being rotated? Is it enough to be uncomfortable for the passengers?

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  31. By John Carpinelli on March 8, 2011 at 4:17 am

    A few points of clarification on the design not explained in the essay:

    1) The hub could support multiple winches and tow planes.  For example, four tow planes could fly in a circle above the hub with ninety degrees of separation between aircraft.  This would result in four times more launch capacity.  

    2) There are many possible combinations of cable length and tow plane speed.  The takeoff system could be configured based on local geography or weather conditions.

    3) The winch/land/winch model is a technique to allow electric air freight to compete with road transportation on price.  There may not be a significant speed difference between electric air freight and diesel trucking, but it could deliver a lower cost per ton-mile and be cleaner.

    4) The rotational acceleration experienced by passengers can be kept at a comfortable level by adjusting the tow plane speed and radius of the flight circle.

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  32. By Benny BND Cole on March 8, 2011 at 12:12 pm

    RR and Thomas398–

    Thanks for your comments.

    Microwave as a weapon? No doubt.

    There was a time that “supercomputers” were outlawed for export. Now you can buy one at Wal-mart. I sense the day of stifling technology for purported military needs is receding into the past.

    I look forward to the practical and civilian applications of SBSP.

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  33. By Jon Brown on March 8, 2011 at 4:34 pm

    This seems way overly complicated… Reading the headline I assumed the idea would be using an electric/maglev type catapult to launch aircraft which would make a lot more sense to me anyway… gotta assume someone is already working on that.

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  34. By Wendell Mercantile on March 8, 2011 at 5:40 pm

    Reading the headline I assumed the idea would be using an electric/maglev type catapult to launch aircraft

    Jon~

    The Navy is working on that, and the next generation of Navy carriers will have electromagnetic, linear induction catapults. But I’m not sure how that would work for commercial aircraft.

    Naval aviators are young and fit, and don’t mind going from zero to 150 knots in two seconds under 4 gs of acceleration. That would be a much harder sell to the majority of the general public who don’t even like to encounter turbulence.

    Navy carrier catapults can only launch aircraft weighing up to about 75-80,000 lbs, whereas a commercial passenger liner or freighter might weigh several hundred thousand pounds.

    The kinds of airplanes that are now launched off catapults are also built robustly and stressed to take punishment. Very few commercial aircraft can handle loads of more than 3.8 gs. Building an airplane to take stress, adds a lot to its weight, and that weight would probably counter the benefits of being able to stand up to a linear induction catapult launch.

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  35. By eugene on March 9, 2011 at 2:13 pm

    As a pilot with several thousand hours of jet time, you do it!! Not for me. This is one of those solutions that looks great until applied, then it’s a disaster. I figure this one by a guy that wants a Federal grant to explore the idea.

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  36. By Wendell Mercantile on March 9, 2011 at 2:53 pm

    I figure this one by a guy that wants a Federal grant to explore the idea.

    Eugene~

    Also by someone who has never had to go through the Federal Aviation Administration’s (FAA) certification process.

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  37. By John Carpinelli on March 9, 2011 at 4:26 pm

    I am not looking for a Federal grant.  I think the system should be prototyped and developed by private industry.  Some entrepreneurs could build a prototype for less than $1m in a few months and then patent the key design elements.  The technology is relatively simple.  Here is a list of major components:

    • electric winches
    • electric tow aircraft
    • Dyneema/HMPE rope
    • aluminum power cable

    These components are commercially available.  You could prototype with the Pipistrel Taurus electric plane for example (http://www.pipistrel.si/plane/…..o/overview).  

    I expect the FAA would write some new rules to regulate the safety of electric take-off.  I do not believe that Federal money is required to develop the technology.  My personal motivations for the technology are the following:

    • make aviation cheaper
    • reduce oil consumption and noise pollution
    • mitigate climate change
    • enable cheap supersonic and suborbital travel in the long term
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  38. By Wendell Mercantile on March 9, 2011 at 10:07 pm

    I expect the FAA would write some new rules to regulate the safety of electric take-off.

    “Some new rules?” Airplane companies such as Boeing and Cessna have entire teams of lawyers and regulatory specialists who do nothing else but shepherd things through the FAA’s regulatory and certification process.

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  39. By rbm on March 10, 2011 at 8:59 pm

    RR -

    I know someone who worked on this problem in the past. He said he got an unfriendly visit from someone in the government – CIA maybe, I forget – because a system like that could be used as a weapon. They were afraid of this being developed and our enemies getting a hold of it.

    Was that stated explicity by the whatever ‘vistior’ ? If so, I’m skeptica of that explanationl given what else can be used as a weapon.

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  40. By Robert Firth on March 11, 2011 at 4:11 am

    Sigh. We had the answer 80 years ago and abandoned it. Buoyant flight. (For the jargon impaired: airships – the most rational form of air transport ever devised)

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  41. By Wendell Mercantile on March 11, 2011 at 9:44 am

    I know someone who worked on this problem in the past. He said he got an unfriendly visit from someone in the government – CIA maybe, I forget – because a system like that could be used as a weapon.

    If it has potential as a weapon, any visit would have likely been by a government agency (perhaps DARPA) wanting to see if the claim is true, figure out how it works, and then make use of it.

    Believe it or not, our government has people who do nothing but continually scan scientific literature and press releases, prowl the Internet, attend symposiums and conferences, and dig into data looking for someone who might have made the next big breakthrough. And when they find that someone, try to exploit it for our own use.

    We had the answer 80 years ago and abandoned it. Buoyant flight.

    Robert Firth,

    Why do you say we’ve abandoned it? Aerospace companies always have people doing R&D on lighter-than-air, and when they find a practical, money-making vehicle, will push it forward and try to sell it. Even today the Zeppelin Company still exists and continues to work on modern versions of the airship: Zeppelin Luftschifftechnik GmbH & Co KG

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  42. By Wendell Mercantile on March 11, 2011 at 11:35 am

    John Carpinelli~

    To add to what I said above, it wouldn’t surprise me if DARPA monitor’s Robert’s blog regularly, and has already started a file on your idea. Although there would be several practical and logistical obstacles to overcome to make it commercially viable, your idea shows original thinking and you are to be commended.

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  43. By Sam Jaffe on March 11, 2011 at 1:31 pm

    John,
    Kudos for proposing a “crazy” idea and then having the guts to put your name behind it. Here’s why it probably won’t work:
    *Weight of cable to lift a modern jetliner would tax the energy efficiencies of the system
    *Size of hauling aircraft would need to be so large to support the weight of the jetliner that significant cost issues would be involved.
    *Safety. The safety implications of raising a box filled with people that weighs hundreds of thousands of pounds and then letting it drop are very significant. Safety is often the graveyard of transportation ideas: even when there are good answers to the questions asked, they might not be good enough to meet the extremely high safety standards required.
    *Extra cost of additional pilots and machinery for each takeoff is also an issue.
    *Imperfection of looped flight cargo lift–As you mention, this concept has been around for decades but is still not used by the military as a matter of course. They prefer helicopters and STOL technologies to this seemingly simpler and cheaper option. Why is that? Maybe it’s not really as effective as its supporters promise.

    Here’s some reasons why it might work:
    *Fuel usage on taxi, takeoff and climb is by far the biggest apple to pick when aviation experts start thinking about how to reduce fuel waste. There’s an audience for ideas like this.
    *Electric aviation is limited by energy storage–the most important aspect of this idea is the perpetually linked tether, which allows for a constant feed of electric power to the aircraft.

    I would suggest that ground based catapulting would be more effective than this. The previous comments about passengers submitting to 3.9 G’s don’t make sense–that has to do with the limited length of an aircraft carrier. A commercial passenger catapult needn’t require such massive acceleration.

    Things you can do to advance your idea:
    *Show really good data on the real fuel usage data for taxiing, takeoff and climb. The simple $650/flight doesn’t have enough specificity to convince anyone.
    *Do more sophisticated modeling of the cost savings of your system.
    *Find real world examples of how some of these systems (such as the cables of this length and strength, etc.) are already in use.

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  44. By rrapier on March 11, 2011 at 1:34 pm

    Wendell Mercantile said:

    John Carpinelli~

    To add to what I said above, it wouldn’t surprise me if DARPA monitor’s Robert’s blog regularly, and has already started a file on your idea. Although there would be several practical and logistical obstacles to overcome to make it commercially viable, your idea shows original thinking and you are to be commended.


     

    I want to second that; this was original thinking and regardless of whether significant obstacles to realization are discovered, it was worth the debate and discussion. We need these sorts of outside-the-box ideas.

    RR

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  45. By david foster on March 12, 2011 at 5:01 pm

    You show a glide ratio of 17:1, which is good for about 100 miles. If the plane has to land and be re-launched every 100 miles, that will cut its effective end-to-end speed by probably at least 3:1, even if there are minimal queuing delays waiting for the runway and the launch facilities.

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  46. By paul-n on March 13, 2011 at 12:58 am

    RR wrote;

    I want to second that; this was original thinking and regardless of whether significant obstacles to realization are discovered, it was worth the debate and discussion. We need these sorts of outside-the-box ideas.

    I’ll third that.  A  major part of technological improvement is by ideas being put forth, discussed, critiqued, experimented etc.  Often the original idea does not pan out, but may lead to secondary ideas that do.  

    In any case, we should be thankful we have forums like this to see and discuss such ideas – if we were in China it may well be a different story.

     

    AS for the idea itself, it is certainly out of the box.  I think the idea of going totally fuelless and repeated re-launch would take too much time, and thus give up the major advantage of air travel, though going totally fuelless does have many positives.  Other than lighter than air flight, as mentioned above, I have not seen any other sensible concepts that allow for oil free flying in large planes, so kudos for this plan.

    The short hop concept could work for somewhere like say, Hawaii, where the islands are within reach of the glide ratio.  Too bad that almost all Hawaii’s electricity comes from oil, so there would be very little saving!

     

     

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  47. By John Carpinelli on March 14, 2011 at 7:51 am

    Robert - Thanks for hosting the electric aviation essay and an excellent discussion on the proposal.

    I think that economics will ultimately decide if the technology succeeds.  A future generation of freight aircraft with a glide ratio of 30 and towed to an altitude of 12 miles would have a glide range of 300 – 350 miles.  These aircraft could deliver air freight at prices comparable to rail and much cheaper than road transport.  If oil prices continue to climb in the next decade, I predict that electric air freight will be implemented.

    In the meantime, more research is required on the economics and technical elements of the design.

    John

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  48. By Joe on March 21, 2011 at 7:21 pm

    Always great to see new out-of-the-box concepts being proposed. While I dislike being a naysayer there are, however, a few obvious reasons why this concept won’t ever get off the ground, some of which have already been noted by other posters.

    Furthermore, the potentially saved fuel is really just a small sliver (and increasingly getting smaller) of overall fuel consumption. Lower hanging fruit still exists to be plucked with lower cost and proven approaches.

    Even if it were technologically feasible, certainly by the time it would ever have a chance of being implemented aviation and ground transport will have changed significantly rendering the concept moot. For example, certainly BWB airliners and/or Open Rotor aircraft have a much greater chance than this concept. In the meantime, there is an active/activist collection of airline and industry CEO’s that are advancing “greener” aviation. For example, we could today eliminate taxi fuel burn since we already have electric aircraft tugs (and Boeing has an electric taxi motor design, for example).

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