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Fisher Flying Products Announces New Electric Propulsion Systems

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231TC

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The electric Pipistrel is a toy. A novelty with no real value. They might sell a few to people with more money the brains.
Or to people who have plenty of brains but also have more money than they need.

Nothing wrong with toys. I own three planes and only one is practical. The others are pretty much just toys, but they still have real value. Fun is valuable.

I'm not buying an electric Pipistrel, but if I had tons of money I probably would.
 

Tiger Tim

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I think one could make a good case that Moore's Law applies specifically to the technologies of electronic data processing. It may have some application outside that narrow realm, but as you note it mostly just raises expectations precluded by basic science and the periodic table of elements.
We’re in total agreement on this, it just looks now like I could have articulated it better.
 

pictsidhe

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If I were to build a fun eplane:

Something like an AR-5 with more span and wing area. Shave some structural weight with plenty of carbon. It would have to fly much slower. With a bit over 1sqft of drag area (AR-5 was 0.88, but we need a big brother), it would fly on low power. Probably start with tesla model S battery modules. If LiS does become available, they will need more volume than equivalent weight Li-ion. Leave space...
 

Dusan

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The electric propulsion characteristics makes it very attractive for me, and aside the obvious reasons, like simplicity, efficiency, noise, affordability, maintenance, it enables or ameliorate the development of new aircraft characteristics, like VTOL. Sure, designing any VTOL aircraft is very hard, as demonstrated plenty from failed designs since 1950's, and slapping together 8 rotors to a fuselage will not do, even if equipped with wings for cruise efficiency.

The most acute problem of all VTOL designs is not solved yet: producing effectively hover lift, but without compromising cruise flight performance. To be hover efficient, a VTOL aircraft needs large rotors - having low disk loading, otherwise the power demand is very high. However, large rotors are detrimental to wing-borne cruise performance, a conundrum of all VTOL concepts, since the creation of the first VTOL aircraft.

The electric propulsion could be very advantageous for a VTOL aircraft, and not for the high efficiency of electric propulsion per se, but for the high efficiency regardless of power setting. A VTOL aircraft has a large disparity in power required for hover versus wing-borne cruising. An ICE (internal combustion engine) designed to hover, is too large and inefficient for cruising.

Batteries, we all know are the limiting factor, having a specific energy about 40 times less than fuel, but an electric motor and it's systems weight is three times less than an equivalent piston ICE. Designing the electrical propulsion for flights under 30-40 minutes might even weight less than the equivalent piston engine.

The high efficiency of electric propulsion is rapidly 'killed' by a draggy air-frame and exposing even more the low energy capacity of the batteries. Puttering at 50 mph with a drag needing 50 KW to overcome it doesn't take you very far. An aerodynamically efficient air-frame is needed for electric propulsion, VTOL or conventional, to bring to life the advantageous characteristics of electric propulsion.
 

Bigshu

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Not sure what the solution is for electric VTOL, but there were several successful VTOL aircraft in the 50's that weren't pursued for production. Dornier DO29, Ryan Vertiplane, Doak 16, all proved hover and good cruise speed were compatible. The Ryan, and Doak used a Lycoming T53 driving multiple props with shafts, and there was a Fairchild prototype that used a GE turboshaft, but it was vey weird. The Doak and the Dornier looked pretty nice, the Ryan and the Fairchild were strange. Used deflected slipstream to help with hover, not just raw engine power. Interesting write ups for most of this stuff in the old Mechanics Illustrated and Popular Mechanics mags of the day.
 

henryk

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=today...
 

jandetlefsen

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Thats a cool site, thanks. I came across the E-Sling Project some time ago. Pretty interesting project, They managed to get buy in from The Airplane Factory who will construct a new wing for the Sling with higher wingspan and some structural enforcements. ETH Zurich is leading the project which is quite something. Of course they can't change the physic but it's gonna be interesting what they end up with.

 

Bigshu

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Batteries weigh a good chunk more than just the cells. You need to physically and electrically connect them together and the aircraft. The latest Pipistrel pack is 154lb and 12.3kWh. Tesla model S 85kWh pack is 1200lbs. Those are actual production packs built by real engineers, not internet 'paper' packs from keyboard experts.

The battery weight is why you cannot have a drop in electric GA engine.
Well, the Tesla pack is supposed to lug around a sedan or SUV at better than highway speeds for 300 miles, so it's sized accordingly. The Pipestrel pack is closer to what an e-plane will start with. Not sure what range it gets, but 20 gallons of Avgas weighs 120lb. Even though that weight decreases with burn, it's still not insignificant. If battery weight continues to come down as it has so far, a pack that will get LSA speed for two hours is easily concievable.
 

12notes

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Well, the Tesla pack is supposed to lug around a sedan or SUV at better than highway speeds for 300 miles, so it's sized accordingly. The Pipestrel pack is closer to what an e-plane will start with. Not sure what range it gets, but 20 gallons of Avgas weighs 120lb. Even though that weight decreases with burn, it's still not insignificant. If battery weight continues to come down as it has so far, a pack that will get LSA speed for two hours is easily concievable.
The Pipistrel battery pack has an energy density of 175 Wh/kg. While a bit better than the Tesla pack's density of 155 Wh/kg, the individual battery pouches energy density of 265 Wh/kg on the Pipistrel is still reduced by a third due to the necessary connections, cooling and casing.

120 lbs (54.4kg) of Avgas has a specific energy of 701kWh. A inefficient gasoline energy has a thermal efficiency of 20%, resulting in a worst case of 140 kWh of delivered energy to the propeller.
120 lbs of Pipistrel battery pack has a specific energy of 9.5 kWh, or 6.8% of the same weight in gasoline. This ignores thermal loss of the electric motor.
120 lbs of Lithium ion battery pouches, ignoring both the necessary weight to make them feasible and motor losses, has a specific energy of 14.4 kWh. This provides an unrealistic best case of 10% of the energy to the propeller for the same weight in gasoline.
120 lbs of the expected to be available soon 400 Wh/kg Lithium Sulfur batteries produce 21.8 kWh of energy.
120 lbs of OXIS'a "goal" of 500 Wh/kg Lithium Sulfur batteries produce 27.2 kWh of energy. This is still only 19% of the energy density of gasoline, and does not take into account the additional packaging weight and thermal losses of the batteries and motors. Factor those in, and you're looking at 17.2kWh of energy, or 12% of gasoline.

Batteries have increased their energy density by weight by 3-5% per year since the 1960's. There have been small jumps, but they are always preceded and followed by slow periods of growth, there has never been a sustained increase or decrease from this number. The introduction of lithium cobalt was one of those small jumps, the introduction of lithium sulfur will be another, however, lithium cobalt has stagnated the last four years at 265 Wh/kg, and that's for the bare pouches. There is no indication or reason to expect anything but 3-5% improvement per year in the future. They have succeeded in making them smaller at a faster rate, as evidenced in the increase in Wh/l, but this has not been the case with mass.

The two hour LSA battery pack is conceivable, but it will take at least 8-10 years to get there.
 

henryk

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E-Sling Project
 

Bigshu

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The Pipistrel battery pack has an energy density of 175 Wh/kg. While a bit better than the Tesla pack's density of 155 Wh/kg, the individual battery pouches energy density of 265 Wh/kg on the Pipistrel is still reduced by a third due to the necessary connections, cooling and casing.

120 lbs (54.4kg) of Avgas has a specific energy of 701kWh. A inefficient gasoline energy has a thermal efficiency of 20%, resulting in a worst case of 140 kWh of delivered energy to the propeller.
120 lbs of Pipistrel battery pack has a specific energy of 9.5 kWh, or 6.8% of the same weight in gasoline. This ignores thermal loss of the electric motor.
120 lbs of Lithium ion battery pouches, ignoring both the necessary weight to make them feasible and motor losses, has a specific energy of 14.4 kWh. This provides an unrealistic best case of 10% of the energy to the propeller for the same weight in gasoline.
120 lbs of the expected to be available soon 400 Wh/kg Lithium Sulfur batteries produce 21.8 kWh of energy.
120 lbs of OXIS'a "goal" of 500 Wh/kg Lithium Sulfur batteries produce 27.2 kWh of energy. This is still only 19% of the energy density of gasoline, and does not take into account the additional packaging weight and thermal losses of the batteries and motors. Factor those in, and you're looking at 17.2kWh of energy, or 12% of gasoline.

Batteries have increased their energy density by weight by 3-5% per year since the 1960's. There have been small jumps, but they are always preceded and followed by slow periods of growth, there has never been a sustained increase or decrease from this number. The introduction of lithium cobalt was one of those small jumps, the introduction of lithium sulfur will be another, however, lithium cobalt has stagnated the last four years at 265 Wh/kg, and that's for the bare pouches. There is no indication or reason to expect anything but 3-5% improvement per year in the future. They have succeeded in making them smaller at a faster rate, as evidenced in the increase in Wh/l, but this has not been the case with mass.

The two hour LSA battery pack is conceivable, but it will take at least 8-10 years to get there.
When's the best time to plant a tree? 20 years ago. When's the second best time? Today. Increases in battery capacity and efficiency are now being driven by existential threat. When all the major European car makers say they're done with ICE by 2025, there's a huge incentive to ramp up the curve on battery technology.
When you talk about the energy density of fossil fuels VS batteries, you can't ignore the fact that 90%+ efficient electric motors do a much better job of using the battery's energy. 20% efficient ICE engine waste tons of btu's of energy throwing off heat that does no work. So the energy density of gasoline isn't a slam dunk in the comparison. I'm just more optimistic about the potential of electric propulsion. I long for the day we can fly quiet, small carbon footprint aircraft that don't contribute as much to global climate change, or spew carcinogens and other toxic chemicals down on our communities. If it's 8-10 years off, that's no reason to shelve the technology, it's every reason to pour more R&D into the technology. What's the alternative?
 

Geraldc

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An electric trainer with quick swap batteries makes sense for a flight school.Pipistrel Alpha Electro fits that mission.
How about an electric helicopter with helipads for charging.
 

12notes

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When's the best time to plant a tree? 20 years ago. When's the second best time? Today. Increases in battery capacity and efficiency are now being driven by existential threat. When all the major European car makers say they're done with ICE by 2025, there's a huge incentive to ramp up the curve on battery technology.
When you talk about the energy density of fossil fuels VS batteries, you can't ignore the fact that 90%+ efficient electric motors do a much better job of using the battery's energy. 20% efficient ICE engine waste tons of btu's of energy throwing off heat that does no work. So the energy density of gasoline isn't a slam dunk in the comparison. I'm just more optimistic about the potential of electric propulsion. I long for the day we can fly quiet, small carbon footprint aircraft that don't contribute as much to global climate change, or spew carcinogens and other toxic chemicals down on our communities. If it's 8-10 years off, that's no reason to shelve the technology, it's every reason to pour more R&D into the technology. What's the alternative?
Perhaps you should read more closely, I reduced the energy of gasoline as if it were burned through an extremely inefficient engine, while ignoring the losses of the electric motor to make the comparison as favorable for the electric as possible, and the numbers still don't work:
12notes said:
120 lbs (54.4kg) of Avgas has a specific energy of 701kWh. A inefficient gasoline energy has a thermal efficiency of 20%, resulting in a worst case of 140 kWh of delivered energy to the propeller.
If you'd like to factor in the losses of the electric motor as well, then the numbers get even worse for the batteries. It is an absolute slam dunk for gasoline right now. In an unrealistically best case scenario for the electric motor, based on a projected energy density which is even higher than a LiS battery that has not yet been produced, ignoring all losses and packaging weight, while comparing it to the delivered energy of gasoline after being burned in a very low 20% efficient engine, results in the electric system having less than 20% of the energy for the same weight. You'd need well over 600 lbs. of batteries to equal 120 lbs. of gasoline in the absurdly optimistic scenario. Making the electric motor system realistic will increase that number that number to around 800 lbs. Using a realistic number for the thermal efficiency of an aircraft engine (Lycoming O-320 is 29.3% efficient - an engine first sold in 1953) would increase the delvered energy of the gasoline to 205kWh, and also increase that equivalent battery weight to nearly 1200lbs - and that's based a hoped for projected improvement to an as-yet-unavailable LiS battery. It's simple math, and it just doesn't work out in favor of electric aircraft at this time - regardless of how those numbers make you feel. If you feel there is an error in the calculation or the numbers these are based on, feel free to point it out.

At no point did I state that electric development should be slowed or abandoned. I am a big fan of electric vehicles and realize they are the future for the majority of transportation needs. The technology is definietly ready for use in cars now for the majority of consumers. I am, however, not a fan of unrealistic expectations and projections based on hopes and wishes instead of facts and hard numbers based on history and reality. By attempting to promote electric planes as practical now or just around the corner before there is any realistic way to make them for anything but niche uses, when they inevitably fail to deliver, it will do nothing but harm future investments in the technologies. I defend realistic projects and I even suggested a possible niche application for electric planes in this thread.

The alternative is making realistic claims, and not making projections based on gains that have no historical precedent by using numbers of technologies that only exist in a lab.
 

Bigshu

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Perhaps you should read more closely, I reduced the energy of gasoline as if it were burned through an extremely inefficient engine, while ignoring the losses of the electric motor to make the comparison as favorable for the electric as possible, and the numbers still don't work:


If you'd like to factor in the losses of the electric motor as well, then the numbers get even worse for the batteries. It is an absolute slam dunk for gasoline right now. In an unrealistically best case scenario for the electric motor, based on a projected energy density which is even higher than a LiS battery that has not yet been produced, ignoring all losses and packaging weight, while comparing it to the delivered energy of gasoline after being burned in a very low 20% efficient engine, results in the electric system having less than 20% of the energy for the same weight. You'd need well over 600 lbs. of batteries to equal 120 lbs. of gasoline in the absurdly optimistic scenario. Making the electric motor system realistic will increase that number that number to around 800 lbs. Using a realistic number for the thermal efficiency of an aircraft engine (Lycoming O-320 is 29.3% efficient - an engine first sold in 1953) would increase the delvered energy of the gasoline to 205kWh, and also increase that equivalent battery weight to nearly 1200lbs - and that's based a hoped for projected improvement to an as-yet-unavailable LiS battery. It's simple math, and it just doesn't work out in favor of electric aircraft at this time - regardless of how those numbers make you feel. If you feel there is an error in the calculation or the numbers these are based on, feel free to point it out.

At no point did I state that electric development should be slowed or abandoned. I am a big fan of electric vehicles and realize they are the future for the majority of transportation needs. The technology is definietly ready for use in cars now for the majority of consumers. I am, however, not a fan of unrealistic expectations and projections based on hopes and wishes instead of facts and hard numbers based on history and reality. By attempting to promote electric planes as practical now or just around the corner before there is any realistic way to make them for anything but niche uses, when they inevitably fail to deliver, it will do nothing but harm future investments in the technologies. I defend realistic projects and I even suggested a possible niche application for electric planes in this thread.

The alternative is making realistic claims, and not making projections based on gains that have no historical precedent by using numbers of technologies that only exist in a lab.
And yet we see new electric aircraft every year. And, the FAA has committed to including electric propulsion in the revised LSA rule. I'm sure this conversation is the same one that buggy whip manufacturers had when ICE vehicles started showing up on roads. We very quickly went from buggys to automobiles. In many ways, the discounting of the value of "niche" uses is part of the problem. Look at the trend towards building STOL aircraft. Those kits are flying off the shelves, and pushing development back on other models. Supply and demand makes the world go around, and people are willing to accept the limitations of the "niche" if it fits their mission.
 

12notes

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And yet we see new electric aircraft every year. And, the FAA has committed to including electric propulsion in the revised LSA rule. I'm sure this conversation is the same one that buggy whip manufacturers had when ICE vehicles started showing up on roads. We very quickly went from buggys to automobiles. In many ways, the discounting of the value of "niche" uses is part of the problem. Look at the trend towards building STOL aircraft. Those kits are flying off the shelves, and pushing development back on other models. Supply and demand makes the world go around, and people are willing to accept the limitations of the "niche" if it fits their mission.
You've completely missed the point of everything I've said. I have said , at least twice in this thread, that there are niche applications that are practical and should be supported. Repeated promotion of unrealistic projects will burn enough investors to poison the well, and will slow investment.

What I've said, in no, way, shape, or form, is in any way to analogous to "buggy whip manufacturers". I've used simple science and math to show why this isn't practical for general use, and definitely not practical for even a two hour range any time soon, you just don't like what the science and math says.

If you need an analogy for the same time period, I am the person in 1900 who is stating that cars are good for short trips and in-city transportation, while refuting the hucksters who are trying to sell a car they claim that can go from New York to California in 3 days, when the engine isn't anywhere near reliable enough, there won't be roads to drive on, and no gas stations along the way, and won't be for decades. The technology isn't there yet, and although it will get there, the time frame will be way slower than these hucksters claim. It'll be 8-10 years for 2 hour range, and 20-30 years for a practical replacement for ICE in GA.

Show me your math and numbers. Prove anything I've said is wrong -
I want to be wrong about this, I'll be happier the sooner that practical electric planes are available for GA.
 

Bigshu

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You've completely missed the point of everything I've said. I have said , at least twice in this thread, that there are niche applications that are practical and should be supported. Repeated promotion of unrealistic projects will burn enough investors to poison the well, and will slow investment.

What I've said, in no, way, shape, or form, is in any way to analogous to "buggy whip manufacturers". I've used simple science and math to show why this isn't practical for general use, and definitely not practical for even a two hour range any time soon, you just don't like what the science and math says.

If you need an analogy for the same time period, I am the person in 1900 who is stating that cars are good for short trips and in-city transportation, while refuting the hucksters who are trying to sell a car they claim that can go from New York to California in 3 days, when the engine isn't anywhere near reliable enough, there won't be roads to drive on, and no gas stations along the way, and won't be for decades. The technology isn't there yet, and although it will get there, the time frame will be way slower than these hucksters claim. It'll be 8-10 years for 2 hour range, and 20-30 years for a practical replacement for ICE in GA.

Show me your math and numbers. Prove anything I've said is wrong -
I want to be wrong about this, I'll be happier the sooner that practical electric planes are available for GA.
You're right, I've mis-characterized your position, and I apologize. I have no doubt your numbers are right, but I think we'll see an explosion of electric aircraft sooner rather than later because of demand push. The practicality will take a back seat to the other motivations that early adopters of new technologies use to make buying decisions (it's been the same with the current crop of electric cars). There's tremendous pent up demand for electric transportation technologies in general, and aircraft in particular. I don't have much patience for hucksters either. But when I see videos of the people actively pursuing these breakthroughs, I hear their passion for the challenge, and I've not heard them trying to sell me pie in the sky. I'm actually looking for some half baked tech to buy that might have a glimmer of hope, but the only integrated systems out there are either from other wrecked vehicles, not for sale at any price, or for sale at typical aviation prices, meaning insanely expensive for what you get.
 

pictsidhe

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Unless somebody starts sinking trillions of dollars into battery tech, long range ecraft are not going to happen soon. EV manufacturers are already making a huge investment.

What I keep seeing with electrical experimenters is not them being unable to obtain reasonable performance electrical stuff, it their attempted use of it in draggy airframes and expecting decent performance.

Wrong, wrong, wrong. This cannot produce anything but mediocre results. It's physics, Jim!

If you want an ecraft, you need to stop looking for a power system that will not be available for decades. Instead, you need to build a low drag airframe that will make the best use of technology that is available now. The motor and batteries are NOT the stumbling block. It's the expectation that current tech can power draggy airframes.

The AR-5 has one of the lowest flat plate drag areas ever measured. 0.88 sqft. It was also built in an old restaurant, instead of a mega buck NASA facility. Seems like a good starting point to me. Educated guesses follow:
We aren't going to build something that can fly at 200mph for long. If we drop to 100, we have about 1/3 the drag after increasing the span and wing area to deal with lower speed. We can go 3 times further for 6 times as long. Perhaps 10-12hp needed for level 100mph flight. A pair of Tesla model S 60lb battery modules would keep us flying for around an hour. Less once you add reserves. Going up to 4 packs may be a good solution. 2 in the nose for balance, 2 in the wings. 100mph and 150miles with reserve seems worth doing to me. It could fly a lot faster for short periods of fun.
 
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