Electric Aircraft with On-Board Power Plant
Abstract
The subject of discussion in this paper concerns a further optimization of an aircraft with on-board power plant. Although the discussion is theoretical, the results could be realized on some prototypes at least. It is about implementing the on-board power plant to generate the electric energy which would be sufficient to supply the propeller engine. There is limitation concerning the optimization of the total weight of aircraft, optimizing the weight of additional equipment necessary to generate electric power. The discussion is based on compairance of the weight to power ratio between power battery packs and on-board generators.
Introduction
The idea of implementing on-board generators is not new. First aircraft which was supplied exclusively with electrical energy and on-board solar power plant has been made in Germany at 1983. The airplane has integrated on-board solar power plant of 2 kW power. Although the solar generators are nowadays much more efficient, having far less weight for more power, their usage is limited on few prototypes. The main reason for this is still very high price of high efficiency solar panels. Although 5 m² of solar panels could generate 9 kW of power, the price for this would amount over $30,000. This seems to be a lot, but it could be rejustified along the time, while the investment is non repetitive. Of this reasons the power battery packs are recently implemented widely, being always more efficient during a time. The rechargeable batteries are also on-board power generators, based on chemical processes. The disadvantage of the rechargeable power battery packs is hidden behind the relatively short lifetime. The heavy duty, thus expensive batteries must be occasionally completely replaced with a new power packs.
Despite of this fact, the light electric aircraft are nowadays preferable for use because of cheaper flight costs, compared to the other aircraft models, above all in business cases where the flight cost have to be optimized, but not the power. The combustion engine aircraft are still more powerful then electrical aircraft, but this limitation is always closer to be crossed over along the time, thanks to the development of the new technologies. Recently the main disadvantage of electric aircraft which implements on-board chemical power generators is still the low range. Implementing an on-board solar power plant would provide non limited range in case of light aircraft, but the price of the solar power plant is still to high.
Being aware of need to stop using a fuel to avoid environmental pollution, along with need to optimize the transportation, we are going to investigate the possibilities of implementing already invented methods and devices, to realize this goal. We are going to implement the universal self-sustained model, which introduce the amplification within the process, combining several methods.
Description
Let us introduce an on-board generator using speeding up an air streams to generate the power. In this particular application, we are going to use the Tesla's friction flat disk turbine US1,06,1206 invented at 1909. The advantage of this type of generator lies in very high rotating speed for relatively low air pressure needed. The system itself is self-sustained because of absence of any resistance except the load.
Abstract
The subject of discussion in this paper concerns a further optimization of an aircraft with on-board power plant. Although the discussion is theoretical, the results could be realized on some prototypes at least. It is about implementing the on-board power plant to generate the electric energy which would be sufficient to supply the propeller engine. There is limitation concerning the optimization of the total weight of aircraft, optimizing the weight of additional equipment necessary to generate electric power. The discussion is based on compairance of the weight to power ratio between power battery packs and on-board generators.
Introduction
The idea of implementing on-board generators is not new. First aircraft which was supplied exclusively with electrical energy and on-board solar power plant has been made in Germany at 1983. The airplane has integrated on-board solar power plant of 2 kW power. Although the solar generators are nowadays much more efficient, having far less weight for more power, their usage is limited on few prototypes. The main reason for this is still very high price of high efficiency solar panels. Although 5 m² of solar panels could generate 9 kW of power, the price for this would amount over $30,000. This seems to be a lot, but it could be rejustified along the time, while the investment is non repetitive. Of this reasons the power battery packs are recently implemented widely, being always more efficient during a time. The rechargeable batteries are also on-board power generators, based on chemical processes. The disadvantage of the rechargeable power battery packs is hidden behind the relatively short lifetime. The heavy duty, thus expensive batteries must be occasionally completely replaced with a new power packs.
Despite of this fact, the light electric aircraft are nowadays preferable for use because of cheaper flight costs, compared to the other aircraft models, above all in business cases where the flight cost have to be optimized, but not the power. The combustion engine aircraft are still more powerful then electrical aircraft, but this limitation is always closer to be crossed over along the time, thanks to the development of the new technologies. Recently the main disadvantage of electric aircraft which implements on-board chemical power generators is still the low range. Implementing an on-board solar power plant would provide non limited range in case of light aircraft, but the price of the solar power plant is still to high.
Being aware of need to stop using a fuel to avoid environmental pollution, along with need to optimize the transportation, we are going to investigate the possibilities of implementing already invented methods and devices, to realize this goal. We are going to implement the universal self-sustained model, which introduce the amplification within the process, combining several methods.
Description
Let us introduce an on-board generator using speeding up an air streams to generate the power. In this particular application, we are going to use the Tesla's friction flat disk turbine US1,06,1206 invented at 1909. The advantage of this type of generator lies in very high rotating speed for relatively low air pressure needed. The system itself is self-sustained because of absence of any resistance except the load.
Additional subsystems such as snail tube, with helix inlet for swirling, thus speeding up the incoming air, along with the jet air suction system installed at an air outlet, are going to be implemented in order to significantly increase the speed of air, thus the kinetic energy of the turbine. Furthermore, just before the input, the nozzle could be introduced to magnify an air inflow into the turbine, as shown on the next image.
The jet air suction system could be reused from an vacuum cleaner based on under-pressure caused by an fast air spinning, such as cyclone, which occurs in numerous bounded nozzles. Furthermore some simple gear has to be introduced to translate the high speed - low torque into low speed - high torque, required to drive a magnetic generator. Combining this simple methods, we could improve an available power of the turbine, keeping the whole system at high power to weight ratio.
What we need is high efficiently power generator, optimized on weight. In the matter of fact, we could use as many turbine-generators on-board as we need. The limiting factor is weight of electric generators. The weight of generators in summary would be slightly larger then the weight of electrical motor, if the motor would not be optimized on efficiency, being over dimensioned in its maximal power. This in turn would enlarge the weight, thus selected solution depends on purpose of aircraft.
Usage of on-board power plant, allows for distributing the weight of numerous generators, along the aircraft. If the weight of all installed turbine-generators is less or equal then the weight of power pack batteries, then implementing of such a system is going to be justified accordingly to extended range. The investment for 9 kW installed power will not going to cross over $5,000 which is recently 6 fold less then the investment to on-board solar power plant. Indeed the investment could be even lower then estimated.
One kilowatt electric generators could be possible to implement using electric motor from e-bike in inverse operation mode. This motors, available on the market, are efficient and have very good ratio power to weight. Thus, nine installed turbine-generators would generate 9 kW of electric power. This would be enough to supply an electric engine of 30 kW power. The mismatching in power of generator and engine, is given due to optimization an aircraft on performance but not on weight. If the weight would be an issue, an engine rated to lower power could be used such as 20 kW. It is to bear in mind that the combustion engine of the same power would have two til three fold larger weight. On need, it would be possible to install a pear of 1 kW generators on the same reduction speed wheel, to get 18 kW of total power. We could also use the stronger generators. Although the turbine could easily speed up very fast, up to 15,000 rpm the very high speed is to avoid, because of preventing of eventually demolishing through vibrations, thus un-wished mechanical resonance effects. Therefore, the speed of 6,000 rpm which would corresponds to 100 rps is going to be introduced. Having a 10” diameter disk stack of 10 disks of 40 mils thick stainless steel, at 40 mils distance from each other, we would have 6 pounds rotor, which could store the kinetic energy of even more then 15 kW mechanical power. All disks have an air outlet holes close to the shaft.
While the suction air inlets of the turbines are placed along the frontal edge of the wings, an air turbulence caused by propeller will going to supply the turbine-generators with air, which is going to speed up within the system. As far the cyclone suction system starts to sucks an air out of turbine, the disks are going to spin faster and faster. This is self-sustained system, while the propeller spinning is directly proportional to the turbine spinning. The maximal speed of turbines rotor is to be kept under the control, thus it should never exceed the limit value.
Conclusion
Using described system, it would be possible to significantly extend the range of electric aircraft. Although the light aircraft are the target group of optimization, also the bigger aircraft could be optimized in order to be driven in mix-mode, extended also their range, thus lowering the costs of transportation.
Special attention should be paid to the turbine design concerning the security. It is to avoid that hard particles fly within the turbine. The non wished oscillations of the turbines rotor have to be prevented, thus the discs have to be high accurate mounted on the shaft. The turbines have to be tested on the ground in different tests before installation is going to be performed.
Even the other types of turbines could be implemented, although their efficiency is going to be slightly lower.
The aircraft of one tone maximal weight, such as Piper Archer LX could be accommodate as described, since the piston engine and gasoline tank, of half a maximal weight could be replaced with 20 – 30 kW electric engine along with an appropriate number of generators to reach the total of 10 – 20 kW. The performance of the aircraft is going to be reduced, such as maximal speed, but the range is going to be non limited.