Sun Flyer, an Electric Trainer Aircraft(spectrum.ieee.org)
spectrum.ieee.org
Sun Flyer, an Electric Trainer Aircraft
http://spectrum.ieee.org/aerospace/aviation/cheaper-lighter-quieter-the-electrification-of-flight-is-at-hand
94 comments
The weight of the electric motors is definitely a lot less, but what most people don't think about is that the main weight of an electric airplane is in the batteries. The battery pack in a Tesla Model S is ~1300 lbs. The batteries required for an aircraft to have an hour long flight time still add too much weight. Batteries have gotten light enough to make it feasible, but we still need major advances in energy density to make electric airplanes make a lot of sense.
Petro-fueled airplanes also have the advantage that they can be flown lighter for short trips, trading off either performance and/or cabin load for fuel load. They also land shorter (by virtue of being lighter) at the end of typical flights.
Battery airplanes that carry the full weight of the batteries all the time have worst-case takeoff, climb, and landing performance on all flights.
It's easy to notice even 100 pounds difference in loading on light airplanes. That's a little under 17 gallons of avgas or about 90 minutes' fuel burn for a typical trainer.
If I want to take 2 extra 175# adults on a local flight, I can just leave off 60 gallons of fuel and have the same performance for a short flight.
Battery airplanes that carry the full weight of the batteries all the time have worst-case takeoff, climb, and landing performance on all flights.
It's easy to notice even 100 pounds difference in loading on light airplanes. That's a little under 17 gallons of avgas or about 90 minutes' fuel burn for a typical trainer.
If I want to take 2 extra 175# adults on a local flight, I can just leave off 60 gallons of fuel and have the same performance for a short flight.
Oh it's definitely marketing. The author constantly uses possessive semantics when describing the work done. It's a neat idea, and I'd like a cheap electric LSA in the future, but that article was pointed right at VC.
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One thing that always bothered me about airplanes is the energy used to take off. On aircraft carriers, they use a launch device, allowing the airplane to "push off" against the carrier. Compare this to airplanes taking off on land, they just nail the throttle and take off by pushing air...
A land-based launch system would have a lot of advantages; lower peak power would be needed from the motor and batteries, the engines could be made smaller, the energy used to take off doesn't have to be stored on the plane, everything gets lighter and more efficient.
A land-based launch system would have a lot of advantages; lower peak power would be needed from the motor and batteries, the engines could be made smaller, the energy used to take off doesn't have to be stored on the plane, everything gets lighter and more efficient.
I'm not sure that it would let you lower the peak power. Most takeoffs aren't limited by runway length. You use full power just because it's safer to get off the ground earlier. Max power requirements come from the maximum altitude the plane is expected to reach, or for multi-engine aircraft the need to be able to climb out after an engine failure.
Aircraft carriers (some of them) use catapults because that's a case where runway length is, by far, the limiting factor.
Aircraft carriers (some of them) use catapults because that's a case where runway length is, by far, the limiting factor.
This is addressed in the article:
"We designed and built a pneumatic rail launcher so that the plane does not have to take off under its own power."
In the spirit of everything old being new again, the Wright Brothers' original 1908 flyer also used a catapult to launch the planes. https://simanaitissays.com/2012/08/13/vintage-aero-wilber-wo...
"We designed and built a pneumatic rail launcher so that the plane does not have to take off under its own power."
In the spirit of everything old being new again, the Wright Brothers' original 1908 flyer also used a catapult to launch the planes. https://simanaitissays.com/2012/08/13/vintage-aero-wilber-wo...
Note that this quote was in reference to the autonomous drone they produce, not the manned trainer that was the subject of the article. I would presume there are more challenges in building a launch assist catapult for a crewed flight.
From the data on the Wikipedia page for the Boeing 747, it looks like the empty weight is around half the maximum take-off weight. Passenger and cargo aircraft seem to usually turn around quite quickly and spend only a small amount of time on the ground. In which case around half of the energy required on take off is just to lift the airframe back to the same altitude it landed from.
Perhaps if aircraft could use some sort of funicular system so that one aircraft taking off could get a "boost" from one slowing down to land?
Or planes could land on giant inflatable runways at 30,000ft, with the passengers and cargo taking a lift down to ground level?
Perhaps if aircraft could use some sort of funicular system so that one aircraft taking off could get a "boost" from one slowing down to land?
Or planes could land on giant inflatable runways at 30,000ft, with the passengers and cargo taking a lift down to ground level?
I would think that most of that energy is used to transport the 747 1/3 of the way around the earth, overcoming induced and parasitic drag for 8+ hours.
From a straight lifting standpoint, lifting 910K pounds to 37K feet takes about 45 billion joules, which is the energy content in about 320 gallons (~2200 pounds) of jet fuel (if consumed perfectly efficiently).
A 747 burns about 1 gallon of fuel per second, meaning the straight lifting fuel consumed represents about 5 minutes or 1% of the fuel consumption on the flight.
From a straight lifting standpoint, lifting 910K pounds to 37K feet takes about 45 billion joules, which is the energy content in about 320 gallons (~2200 pounds) of jet fuel (if consumed perfectly efficiently).
A 747 burns about 1 gallon of fuel per second, meaning the straight lifting fuel consumed represents about 5 minutes or 1% of the fuel consumption on the flight.
>> "... lower peak power would be needed..."
While it is true that you "nail the throttle" during takeoff in a little general aviation Cessna, the same is not true of jet-powered heavy metal. The big planes that account for most passenger miles are limited by engine noise regulations and scaring passengers, and run the engines at a fraction of peak power during takeoff.
You can find implausible-looking-but-true videos of big ungainly airplanes taking off near the edge of the flight envelope in ways that look very surprising.
While it is true that you "nail the throttle" during takeoff in a little general aviation Cessna, the same is not true of jet-powered heavy metal. The big planes that account for most passenger miles are limited by engine noise regulations and scaring passengers, and run the engines at a fraction of peak power during takeoff.
You can find implausible-looking-but-true videos of big ungainly airplanes taking off near the edge of the flight envelope in ways that look very surprising.
Catapults don't save energy--they shorten runway. The jet is at full throttle on takeoff and military aircraft are not exactly fuel misers.
Sure, they don't save energy in the sense that the laws of physics must still be obeyed- but by using the power of the catapult to increase the plane's velocity at takeoff, the motor can be optimized for flight rather than takeoff and less battery weight needs to be carried.
That's because catapults are used in places where space is at a premium. Catapult + full throttle will minimize takeoff length. But if space wasn't at a premium, then surely throttles could be reduced, no?
This has been proposed many times but doesn't seem to be practical or cost effective. The airport infrastructure investment would be huge. And aircraft would have to be redesigned so that the nose wheel (catapult attachment point) could handle a much higher sheer force. Making those parts stronger adds weight, which wastes energy during the rest of the flight.
1. Aircraft use 100% power in situations other than takeoff, so it's hard to see how you could lower peak power/use smaller engines just by eliminating takeoff.
2. Typical aircraft takeoff roll is under 30 seconds, and most aircraft have 3hours+ endurance, so you'd be extending the range of the aircraft by < 1/360th.
2. Typical aircraft takeoff roll is under 30 seconds, and most aircraft have 3hours+ endurance, so you'd be extending the range of the aircraft by < 1/360th.
That's a lot of infrastructure to maintain, and significantly increases the costs of airports.
For the record, this is not new. Pipistrel has had a relatively successful electric trainer for a couple years now based on one of their popular LSA airframes. The only catch is that at this time I don't believe it has yet achieved FAA certification in the states.
Flight instruction is currently about $100-120/hr for aircraft rental and $40/hr for the instructor (not paid if you are soloing). This would likely halve the rate for the aircraft as fuel is currently averaging about $4.50/gallon and a C172 burns on the order of 6-8 gallons/hour and requires more maintenance. Insurance on electric aircraft will likely be cheaper too given the lower mechanical complexity, though this has yet to be seen.
Flight instruction is currently about $100-120/hr for aircraft rental and $40/hr for the instructor (not paid if you are soloing). This would likely halve the rate for the aircraft as fuel is currently averaging about $4.50/gallon and a C172 burns on the order of 6-8 gallons/hour and requires more maintenance. Insurance on electric aircraft will likely be cheaper too given the lower mechanical complexity, though this has yet to be seen.
Fuel ends up being about $50 an hour (depending on the price of fuel, but most C172 trainers burn close to 11 gal/h). While an electric trainer would save almost all of that money in fuel costs, most FBOs don't pay for a _new_ C172 they but one of the thousands of used ones. Buying a new electric trainer would be quite a bit more expensive than a used C172 and I'm sure that would change their rental rates for the aircraft. I think it's likely to offset the cost savings you'd get otherwise. Then again, maybe with the additional reduction in maintenance costs it might end up a bit cheaper to fly.
I actually just emailed sunflyer about pricing since that's the biggest factor initially. I will update if they get back to me. I suspect that they'll be relatively inexpensive compared to a new C172SP @ around $330,000. Maintenance is the biggest difference IMO. Aircraft ICEs burn through oil and parts like nobody's business and only last ~2000hrs before they need a $20+k overhaul. The motors should last the life of the airframe, but this will be offset by battery degradation. By the time these need battery replacement, it could be quite cheap though.
> Aircraft ICEs burn through oil and parts like nobody's business
Yikes, trainers don't have turboprops yet? I get that the initial cost would be higher (though not that much, I would think), but engine on time is the commodity that training airfields sell, it seems ludicrous that they would accept the piston tax.
Yikes, trainers don't have turboprops yet? I get that the initial cost would be higher (though not that much, I would think), but engine on time is the commodity that training airfields sell, it seems ludicrous that they would accept the piston tax.
A 550hp PT6 turboshaft engine (pretty much the smallest one you'll see in use) is around $300k new. OEM pricing on an IO-360 180hp piston engine is about $30k. Turbocharged engines in the same hp range as the PT6 can be had for around $100k.
The dirty secret they don't tell you is that turboprop's have miserable efficiency. A 1950's era carborated piston will outperform them every time in terms of fuel economy. The Cessna caravan or Pilatus PC12 will burn on the order of 50gal/hr of jet fuel at cruise and as turbine engines get smaller, they lose further efficiency.
The dirty secret they don't tell you is that turboprop's have miserable efficiency. A 1950's era carborated piston will outperform them every time in terms of fuel economy. The Cessna caravan or Pilatus PC12 will burn on the order of 50gal/hr of jet fuel at cruise and as turbine engines get smaller, they lose further efficiency.
Seems like the cost would be ludicrously higher. With some brief searching around, it looks like small single-engine turboprops cost well over a million dollars and cost hundreds of dollars per hour to run. You can get a new Cessna 172 for about $200,000, and it'll cost in the neighborhood of a hundred dollars an hour to run. Or get a light sport trainer for $100,000 or so.
Turbo prop aircraft are generally above 200 hp and therefore are considered high-performance aircraft by the FAA. High performance aircraft generally are much more difficult for takeoff and landing because they fly so much faster which makes them unsuitable for a new pilot to learn on.
Why are GA aircraft so expensive? A C172 seems much simpler mechanically than a car. I can see that the price would be driven up by low volume and probably a much stricter QA/inspection process... Is that it, or am I missing something?
You're pretty close. Basically they used to be about the price of a nice car, but it become fashionable to sue the pants off everyone who was involved with the manufacture of the airframe if it was involved in a crash, fatal or not. An entire sector of lawyers emerged, taking advantage of lax regulation surrounding liability in the sector. This began at the end of the 70s and the prices skyrocketed to the point where Cessna actually ceased production of the 172 airframe. Congress had to get involved and passed the GA Revitalization Act which, among other things, limited liability duration on airframes. This was enough to cause the 172 to return to production but I've heard that something like half of the total cost of a new 172 is for liability insurance. This become apparent when you start to look at newer designs that have similar price tags and seat counts like the SR-20/22 line. For $330k you get a skyhawk that can barely break 110ktas. For $400k you get a composite Cirrus with better performance than a 182 (the next level up in Cessna's line). It's also possible that the inclusion of the whole airframe parachute system in the Cirrus design was enough to get the insurance companies to give them a little more of a break.
The other big factor is the construction. Cars are largely stamped and then welded together. Aircraft are either stamped/milled aluminum that is then manually riveted together (production volumes are orders of magnitude lower than cars so no robots are used) or they are made of fiberglass/carbon fiber composite which is even more labor intensive to form. The issue with the comparison with cars is that they're way cheaper than they reasonably should be because of the sheer volume that they produce. In the time it takes cessna to build one plane, ford can pump out 1000 new cars.
The other big factor is the construction. Cars are largely stamped and then welded together. Aircraft are either stamped/milled aluminum that is then manually riveted together (production volumes are orders of magnitude lower than cars so no robots are used) or they are made of fiberglass/carbon fiber composite which is even more labor intensive to form. The issue with the comparison with cars is that they're way cheaper than they reasonably should be because of the sheer volume that they produce. In the time it takes cessna to build one plane, ford can pump out 1000 new cars.
Regulations and bureaucracy. Some of it is justifiable, but a lot of it is probably not responsible for saving any lives. You can legally sell, buy, and fly an aircraft that doesn't pass most of these certification procedures; but for some reason you can not make a business of operating it.
In my humble opinion, the FAA does a lot more than an air regulatory agency should[0].
Since plane crashes are rare enough, the government litigates against everyone who ever worked on your plane if somebody ever dies in connection with it, and unless you can prove it was user error (expensive in its own right), you will end up paying millions in settlements and process. These costs are added at every level of the supply chain.
The FAA process could seem to make aviation safer if aviation technology never had to change ever again; but because there is so much to be done in private aviation that won't ever be done because of the cost of certifying craft with new technology; there's a good chance that safety devices have been held up by the process as well.
[0]: https://fee.org/articles/how-the-faa-brought-down-uber-for-p...
In my humble opinion, the FAA does a lot more than an air regulatory agency should[0].
Since plane crashes are rare enough, the government litigates against everyone who ever worked on your plane if somebody ever dies in connection with it, and unless you can prove it was user error (expensive in its own right), you will end up paying millions in settlements and process. These costs are added at every level of the supply chain.
The FAA process could seem to make aviation safer if aviation technology never had to change ever again; but because there is so much to be done in private aviation that won't ever be done because of the cost of certifying craft with new technology; there's a good chance that safety devices have been held up by the process as well.
[0]: https://fee.org/articles/how-the-faa-brought-down-uber-for-p...
I think a lot of the regulation makes more sense once you understand that the FAA prioritizes different lives differently.
Roughly, they consider these groups, from lowest to highest priority in terms of keeping them safe:
1. Pilots. These are the lowest priority because they're the most in control and best understand the risks. If a pilot wants to turn himself into a red splat, that's his own concern.
2. Knowledgeable passengers. These are people who may not be pilots but understand aviation to some extent and have an idea of what they're getting into. They can't necessarily evaluate all the risks completely, but they can do a pretty good job of it. The FAA can't directly determine this, of course, but they use "for hire" as a proxy: if you're just taking people for fun or as a favor, it's assumed they have some idea of what they're getting into. If they're outright hiring you to fly them around, it's assumed they don't.
3. Passengers who are random members of the general public. Most of these people know little about airplanes and about the risks. They can't be counted on to evaluate things for themselves. People paying random pilots/companies to fly them around are assumed to be in this category. (And people buying tickets on a regularly-scheduled airline flight are assumed to be even more random than people hiring a charter, for example.)
4. The general public on the ground. These people aren't even involved in the process and have no choice in the amount of risk they're exposed to.
This is why the requirements get steeper as you move from recreational flying to commercial flying. If you want to fly solo over empty land, they don't care too much if you get yourself killed. If you're going to carry a hundred vacation travelers who just want to get to the beach, things are more strict.
Roughly, they consider these groups, from lowest to highest priority in terms of keeping them safe:
1. Pilots. These are the lowest priority because they're the most in control and best understand the risks. If a pilot wants to turn himself into a red splat, that's his own concern.
2. Knowledgeable passengers. These are people who may not be pilots but understand aviation to some extent and have an idea of what they're getting into. They can't necessarily evaluate all the risks completely, but they can do a pretty good job of it. The FAA can't directly determine this, of course, but they use "for hire" as a proxy: if you're just taking people for fun or as a favor, it's assumed they have some idea of what they're getting into. If they're outright hiring you to fly them around, it's assumed they don't.
3. Passengers who are random members of the general public. Most of these people know little about airplanes and about the risks. They can't be counted on to evaluate things for themselves. People paying random pilots/companies to fly them around are assumed to be in this category. (And people buying tickets on a regularly-scheduled airline flight are assumed to be even more random than people hiring a charter, for example.)
4. The general public on the ground. These people aren't even involved in the process and have no choice in the amount of risk they're exposed to.
This is why the requirements get steeper as you move from recreational flying to commercial flying. If you want to fly solo over empty land, they don't care too much if you get yourself killed. If you're going to carry a hundred vacation travelers who just want to get to the beach, things are more strict.
Sure, but no aviation company actively dabbles in endangering the life of its customers or members of the public through negligence anyway. In the case of an incident, settling with the victims is going to be enormously costly with or without aviation-specific regulations. Regulations that insure the NTSB has resources to follow up on incidents make a lot of sense, so do ones on accounting (in manufacturing and maintenance); but it's hard to imagine what positive effect the FAA could have outside of that.
Plenty of companies have dabbled in it through lax maintenance, insufficient training, or crew overwork. It may be hard to find ones doing it now, but much of that is because of the FAA's push for safety.
(And I don't know that it is actually hard to find ones doing it now. Certainly the airlines are almost ludicrously safe, but the context here is GA, where things can be much more lax.)
(And I don't know that it is actually hard to find ones doing it now. Certainly the airlines are almost ludicrously safe, but the context here is GA, where things can be much more lax.)
Safety is overrated. In CA it makes sense to strive for it, and boy, it's safe enough that people are worried about radiation! But in GA I feel like a bit more risk is incurred for productivity and efficiency reasons. Some stupid risks are taken, but I figure that's because the market tolerates it. Smaller planes also tend to generate less risk on the ground. Who am I to say that they should be safer; people are happy to drive cars of all things, no matter how crazy they must be to undertake that risk.
Statistically speaking light aircraft are closer to motorcycles in terms of fatalities. On the bright side though, you're much less likely to me maimed in an aircraft accident :)
When people get upset about the FAA's safety stance in GA, it has less to do with the part 61/91 regulations (airman certification/operating procedures) and more to do with the equipment certification standards. A common example is the reliance on vacuum driven gyroscopic instruments when MEMS technology provides better performance with a much lower probability of failure. Up until recently the FAA made it almost impossible to retrofit old aircraft with generic glass panel systems even though these systems provide vastly greater safety margins when used correctly. I personally have experienced a vacuum system failure, but luckily not while in IFR conditions.
Beyond instruments, the bulk of the fleet of 30-50 years old and beginning to show it's age, but it's prohibitively expensive to certify new designs that incorporate more safety features like CAPS (parachute systems), composite energy absorbing seats/fuselages or digital engine management systems. We're also still entirely reliant on leaded fuel (100LL) due to cost hurdles in certifying engines that can run on JetA or anything else for that matter.
When people get upset about the FAA's safety stance in GA, it has less to do with the part 61/91 regulations (airman certification/operating procedures) and more to do with the equipment certification standards. A common example is the reliance on vacuum driven gyroscopic instruments when MEMS technology provides better performance with a much lower probability of failure. Up until recently the FAA made it almost impossible to retrofit old aircraft with generic glass panel systems even though these systems provide vastly greater safety margins when used correctly. I personally have experienced a vacuum system failure, but luckily not while in IFR conditions.
Beyond instruments, the bulk of the fleet of 30-50 years old and beginning to show it's age, but it's prohibitively expensive to certify new designs that incorporate more safety features like CAPS (parachute systems), composite energy absorbing seats/fuselages or digital engine management systems. We're also still entirely reliant on leaded fuel (100LL) due to cost hurdles in certifying engines that can run on JetA or anything else for that matter.
The FAA certification has a lot to do with it. Little parts you'd think would be cheap (say, a lightbulb) end up costing a ton of money because they have to go through a rigorous testing and certification process.
Here are some LED landing lights for a C172 for the low low price of $227: http://www.knots2u.net/categories/cessna-single-engine-model...
Here are some LED landing lights for a C172 for the low low price of $227: http://www.knots2u.net/categories/cessna-single-engine-model...
In the UK it's a lot more expensive, around £190 for an hour's flying lesson in a C152 (2-seater).
Pipistrel as a maximum flight time of 1 hour not sure what is the predicted flight time on the Sun Flyer.
They will babble about 4 hour flight times (and not mention that they're talking about 4 hours at <50kts) but at the end of the day, everyone has to contend with the same battery tech. All current airframes in the category are looking at about an hour of 65% power.
A good rule of thumb is that nobody is going to be getting more than twice the flight time of a state of the art quadcopter.
A good rule of thumb is that nobody is going to be getting more than twice the flight time of a state of the art quadcopter.
Please someone invent better batteries that can be mass produced. My drone, my airplane, my car and my phone desire you!
does anyone know the viability of hydrogen fuel cell electric motor airplanes? It seems like this is a more logical step, since from what I've read the energy density of batteries really isn't optimal for something like an airplane, even with technologies projected to come to market in the next couple of decades. And the whole thing still has the possibility of being zero-emissions.
> And the whole thing still has the possibility of being zero-emissions.
Well, so does a hybrid plane, if it's fueled with biofuels. Zero net CO2 emissions anyway. I would imagine other emissions are less problematic since it happens far away from populated areas.
I'm not sure why hydrogen is desirable. Hydrocarbons have higher energy density and is easier to store and fuel.
I can imagine that the closed loop of H2O + electricity <-> electricity + H2 + O is more efficient than the hydrocarbon equivalent. But neither technology is near their theoretical limits, so it's a bit hard to say yet.
Regardless, if we build hybrid planes, we can use whatever technology makes the most sense. It shouldn't be too hard to swap out the energy storage mechanism. Who knows, maybe we'll invent a good rechargeable aluminum-air battery and replace everything with that.
Well, so does a hybrid plane, if it's fueled with biofuels. Zero net CO2 emissions anyway. I would imagine other emissions are less problematic since it happens far away from populated areas.
I'm not sure why hydrogen is desirable. Hydrocarbons have higher energy density and is easier to store and fuel.
I can imagine that the closed loop of H2O + electricity <-> electricity + H2 + O is more efficient than the hydrocarbon equivalent. But neither technology is near their theoretical limits, so it's a bit hard to say yet.
Regardless, if we build hybrid planes, we can use whatever technology makes the most sense. It shouldn't be too hard to swap out the energy storage mechanism. Who knows, maybe we'll invent a good rechargeable aluminum-air battery and replace everything with that.
It's worth noting that burning jet fuel at airliner flight altitudes is roughly 2x as bad for the climate as the carbon emissions alone would suggest:
http://www.ipcc.ch/ipccreports/sres/aviation/index.php?idp=6...
http://www.ipcc.ch/ipccreports/sres/aviation/index.php?idp=6...
why does bio-fuel mean net zero emissions? I assume you're talking about bio-disel or ethanol? Don't both of these still produce cO2 when you burn them?
But if you're producing the hydrogen with zero emissions, then it's a 100% cO2 free process, isn't it?
But if you're producing the hydrogen with zero emissions, then it's a 100% cO2 free process, isn't it?
When a tree makes wood, it takes CO2 out of the atmosphere. When you burn the wood, you release exactly that carbon.
Similar for making ethanol.
Similar for making ethanol.
Hydrogen storage ain't easy. It's not the motors that are the problem in weight, but hydrogen storage tanks or electric batteries.
Also, perhaps it doesn't have to travel as far as conventional airplanes. Perhaps it can be okay to be twice as slow (because of more stops and lower powered engines) if it's only slightly cheaper.
Trains and long distance busses are still around for routes that are also trafficked by airplanes. Presumably because they are often cheaper.
Trains and long distance busses are still around for routes that are also trafficked by airplanes. Presumably because they are often cheaper.
I guess I was more extrapolating to jet engines, where I don't know if speed is as much of a factor in energy conservation, given the market.
Is there any way to do the analogous of regenerative braking on the descent in an electric airplane?
>A bonus: The airplane can regenerate energy during braking, just as electric cars do. When the pilot slows down or descends, the propeller becomes a windmill, running the motor as a generator to recharge the batteries. In the sort of airport traffic pattern typical for general aviation and student-pilot training, this energy savings comes to about 13 percent. In other words, if a plane lands having apparently used 8.7 kWh during the flight, it has actually used 10 kWh—the propeller-recoup system put back roughly 1.3 kWh while flying in the traffic pattern.
I think the issue is that by the time you are on descent, the flight is nearing an end, so the benefits for range extension aren't great.
In this case, the students will likely be doing pattern work in these aircraft which involves repeated takeoff and tochdown. In particular they will often do a touch-and-go where the aircraft maintains forward speed and takes off again. In this case, the regeneration should allow one extra circuit for every ten or so circuits.
Not really. You take the potential energy stored in the airplane and use it to transit to the airport. On my (gasoline) airplane, I fly most of the descent under significant positive thrust/power (150+ HP worth of positive power, often over 200 HP).
The only time I could see wanting net regenerative power is on very short final (the last 50 feet of descent) or for braking on the runway (especially on contaminated runways). But neither of those will be effective for regen/extending range.
The only time I could see wanting net regenerative power is on very short final (the last 50 feet of descent) or for braking on the runway (especially on contaminated runways). But neither of those will be effective for regen/extending range.
Maybe they could install bicycle cranks so the pilot and passengers can all pedal their way through the air.
Yes, the props rotate backwards - it's called windmilling.
I didn't read the whole article, but if they even mentioned how long it will fly for, they sure hid that carefully. Stop wasting my time until you have a decent product!
They mentioned 83 kWhr battery, a peak power usage of 80 kW, and a "normal flight", whatever that means, usage of around 20 kW.
I should note that a conventional airplane rarely cruises at less than 50% power, 65-75% would be more common.
But even an hour endurance, plus reserves, is okay for a trainer airplane, so this product is pretty decent already, and your outrage over the waste of your precious time probably was not warranted.
If this thing can recharge in ~30 mins, then it would be a pretty good option for a flying school, where pre-flight briefings and checks will consume a part of this time.
And given the pre-orders and options, it seems the flying schools in fact agree that this is a pretty good product.
I should note that a conventional airplane rarely cruises at less than 50% power, 65-75% would be more common.
But even an hour endurance, plus reserves, is okay for a trainer airplane, so this product is pretty decent already, and your outrage over the waste of your precious time probably was not warranted.
If this thing can recharge in ~30 mins, then it would be a pretty good option for a flying school, where pre-flight briefings and checks will consume a part of this time.
And given the pre-orders and options, it seems the flying schools in fact agree that this is a pretty good product.
While doing circuit training, a student pilot can do 5 training circuits of 6 mins each using 30 minutes of battery. They'll probably be so overwhelmed and fatigued afterwards (well, I was anyway) that their day's training is over. That's five or six exhausted student pilots per exhausted battery. :)
3 hours of flight time is more than adequate for training purposes. Not only is it a huge win for fuel savings, but safety is the number one reason I can see primary trainers going 100% electric over the next decade. Learning to deal with the intricacies of an ICE across the full range of flight conditions is half your training time wasted, and the myriad of things that can go wrong simply wont exist anymore.
Unfortunately that defeats the purpose of a trainer, because "real" planes, which the trainer is supposed to prepare you for, won't be electric for quite a bit, so you do need to learn all about the intricacies and issues which can crop up on those planes.
Even assuming a rather speedy pace of improvement in battery tech, the power/weight ratio won't be there for quite a while. Batteries also don't get lighter as their energy is consumed, like fuel does, and many planes cannot even land with the same weight they are allowed to take off with.
Even assuming a rather speedy pace of improvement in battery tech, the power/weight ratio won't be there for quite a while. Batteries also don't get lighter as their energy is consumed, like fuel does, and many planes cannot even land with the same weight they are allowed to take off with.
Of course, this means a student can start in this electric trainer, and focus on learning the flying right off the bat.
When a student has that down, they can graduate up to a trainer with an ICE, and then learn all of that stuff.
Exactly like learning to drive a car in an automatic first, then once you have the actual vehicle control/traffic/etc down, you graduate up to a stick shift.
When a student has that down, they can graduate up to a trainer with an ICE, and then learn all of that stuff.
Exactly like learning to drive a car in an automatic first, then once you have the actual vehicle control/traffic/etc down, you graduate up to a stick shift.
Except that in countries where stick shift dominates, you start off learning to drive a stick right away.
Unlike airplanes, cars have no stall speed. You first lesson involves driving at very low speeds, away from traffic. If you have any trouble shifting you can just stop. Airplanes are less forgiving.
Electric vs ICE trainers won't have much in the way of differences. The main procedural differences will be engine start (just follow the checklist) and low power conditions where carb heat is required (becoming slightly less common now that fuel injection is available and relatively cheap). The most common trainer is the C172 which is high wing and therefore doesn't need an electric fuel pump or tank switching so that's about it.
That's why you have an instructor.
Just as a decent driving instructor won't let you blow a red light, a decent flight instructor (who has the ability to take control of the aircraft, unlike a driving instructor) isn't going to let you enter an unplanned stall, or leave you on your own to deal with more than you're ready to handle at any given time.
Just as a decent driving instructor won't let you blow a red light, a decent flight instructor (who has the ability to take control of the aircraft, unlike a driving instructor) isn't going to let you enter an unplanned stall, or leave you on your own to deal with more than you're ready to handle at any given time.
>Unfortunately that defeats the purpose of a trainer, because "real" planes, which the trainer is supposed to prepare you for, won't be electric for quite a bit, so you do need to learn all about the intricacies and issues which can crop up on those planes.
Not at all. The vast majority of primary flight training is best spent on so called "stick and rudder" skills. The basics of flying do not change at all from an electric powered ultralight to a Boeing 777.
Not at all. The vast majority of primary flight training is best spent on so called "stick and rudder" skills. The basics of flying do not change at all from an electric powered ultralight to a Boeing 777.
It hardly "defeats the purpose." You'll still learn to fly. You just won't learn to manage engines, which you can learn later on. Learning the two things separately is probably a good thing, since it'll let you focus on one thing at a time.
This isn't a new concept, either. It's relatively common to learn to fly gliders before transitioning to powered aircraft. The US Air Force Academy has the largest glider operation in the world, for example.
This isn't a new concept, either. It's relatively common to learn to fly gliders before transitioning to powered aircraft. The US Air Force Academy has the largest glider operation in the world, for example.
> Learning to deal with the intricacies of an ICE across the full range of flight conditions is half your training time wasted
I'm not familiar with flight terminology or flight training, so could you elaborate on the meaning of that sentence?
I'm not familiar with flight terminology or flight training, so could you elaborate on the meaning of that sentence?
ICE = Internal combustion engine
Off the top of my head:
- At certain temperatures and pressures you have to consider icing in the carburettor, which will block air flow into the engine.
- You have to tune (lean) the fuel input to reduce fuel consumption and prevent spark plug fouling, but not lean it too much that you overheat the engine.
Some more in-depth examples at http://philip.greenspun.com/flying/engine-management
Off the top of my head:
- At certain temperatures and pressures you have to consider icing in the carburettor, which will block air flow into the engine.
- You have to tune (lean) the fuel input to reduce fuel consumption and prevent spark plug fouling, but not lean it too much that you overheat the engine.
Some more in-depth examples at http://philip.greenspun.com/flying/engine-management
And when descending, you have to be sure not to shock cool it etc.
Airplane gasoline engines are a mess, the technology is ~1950s at best and just hasn't advanced at all, with a few exceptions that, pardon the pun, never really took off.
Airplane gasoline engines are a mess, the technology is ~1950s at best and just hasn't advanced at all, with a few exceptions that, pardon the pun, never really took off.
Shock cooling as a concern for cylinder cracking is a fairly well debunked myth at this point, IMO, short of crashing your airplane into a cold lake.
Agreed the tech is old, but the uncommanded in-flight shutdown rate for pistons is also very low. Part of that is driven by high maintenance demands (some of which introduces failures themself), but a lot is due to the simplicity and redundancy.
Would I like variable spark timing (beyond impulse couplers for starting)? Would I like more automated starting, especially for hot starts? Would I like thermostatic cooling of cylinders? Yes, but not if they came with any substantial increase in failure modes. When I'm taking the family 700 miles at night in a single-engine airplane to grandma's for christmas, I'll suffer with arcane checklists and having to manually manage the engine if it reduces the chance of an uncommanded shutdown by even 5%.
Agreed the tech is old, but the uncommanded in-flight shutdown rate for pistons is also very low. Part of that is driven by high maintenance demands (some of which introduces failures themself), but a lot is due to the simplicity and redundancy.
Would I like variable spark timing (beyond impulse couplers for starting)? Would I like more automated starting, especially for hot starts? Would I like thermostatic cooling of cylinders? Yes, but not if they came with any substantial increase in failure modes. When I'm taking the family 700 miles at night in a single-engine airplane to grandma's for christmas, I'll suffer with arcane checklists and having to manually manage the engine if it reduces the chance of an uncommanded shutdown by even 5%.
Rotax seem to be doing pretty well, they're used in a lot of popular trainers
A lot of that "mess" is due to a couple of critical requirements. Namely, low engine weight and reliability.
At this point it's mostly certification cost and liability insurance cost that's keeping the tech back. You can easily modify modern aircraft engines to be more reliable and efficient (PMAGs) but you need an STC (certification procedure) to make the switch so the experimental home builders are the only ones who actually benefit.
> carburettor
Excuse me? Carburettor? In 2017?
> You have to tune (lean) the fuel input to reduce fuel consumption and prevent spark plug fouling, but not lean it too much that you overheat the engine.
Can't the engine management software take care of this?
Excuse me? Carburettor? In 2017?
> You have to tune (lean) the fuel input to reduce fuel consumption and prevent spark plug fouling, but not lean it too much that you overheat the engine.
Can't the engine management software take care of this?
An average car company makes millions of cars. Probably millions of a given model. Cessna has made ~44k 172 Skyhawks. It's one of the most produced aircraft, and it's been in production largely unchanged since 1956. I think Tesla is going to make more Model 3s this year than Cessna is going to make Skyhawks.
Don't they cost hundreds of thousands of dollars? Surely you're going to find an engine manufacturer that can build you an engine that's not half a century old.
If it ain't broke...but the 172[R and S] has been using a fuel-injected engine since 1996[0]
[0]https://en.wikipedia.org/wiki/Lycoming_O-360
[0]https://en.wikipedia.org/wiki/Lycoming_O-360
And the flight hour cost of one of these is double the price of a 1970s/80s carbureted 152. Guess which one the majority of student pilots are learning on.
Of course, and if you want something like that, you can find aircraft manufacturers using more modern engines. Want a car engine in an airplane? You can have that. Want a fuel-injected digitally-controlled turbocharged water-cooled diesel? Step right this way.
The big, old manufacturers like Cessna tend to be really conservative, though. They have something that's Good Enough and they have little incentive to make radical changes. Part of this is because a light aircraft's powertrain is safety-critical, unlike automobiles. In a car, if your engine explodes, you're stranded. In a small airplane, depending on where you are when it happens, you're probably hurt or killed. If you make a radical change to your engine, and that change results in a failure that kills a customer, it looks bad. Newer manufacturers seem more willing to push the envelope in this respect.
The big, old manufacturers like Cessna tend to be really conservative, though. They have something that's Good Enough and they have little incentive to make radical changes. Part of this is because a light aircraft's powertrain is safety-critical, unlike automobiles. In a car, if your engine explodes, you're stranded. In a small airplane, depending on where you are when it happens, you're probably hurt or killed. If you make a radical change to your engine, and that change results in a failure that kills a customer, it looks bad. Newer manufacturers seem more willing to push the envelope in this respect.
What's this "engine management software" you speak of? :-)
Seriously, GA aircraft engines are seriously old tech.
Seriously, GA aircraft engines are seriously old tech.
You can indeed get engine management computers, but the thinking in the aviation world is that this would be just another thing that could go wrong. In any case, if the computer were to fail, the pilot would have to know how to manage the engine manually. Aircraft engines have various design choices designed to make the things more reliable, such as dual independent ignition systems that are isolated from the battery. The pilot deliberately has independent control over things like fuel/air mixture for good reasons.
Most flight schools have much older aircraft-- think 70s and 80s-- that have carbs. Newer aircraft are fuel injected, but often more expensive per hour.
VW Golf are fuel injected since 1975.
Cars are different, though you could have pointed out that the Messerschmitt BF-109 had fuel injection in the 1930s.
But they've only been able to fly since 2016.
ICE = Internal Combustion Engine.
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Wasted? Isn't that exactly among the things you need to learn?
So you can have an electric plane for primary training, and ICE as the next step?
Lots of people learn to drive automatics and not manuals. Perhaps electric planes will become viable enough that many people will never need to progress to ICE?
Lots of people learn to drive automatics and not manuals. Perhaps electric planes will become viable enough that many people will never need to progress to ICE?
Sure, but that hardly means it is wasted.
And perhaps that is true, but hardly the case in the near future.
And perhaps that is true, but hardly the case in the near future.
> We designed the aircraft for the niche application of pilot training, where the inability to carry a heavy payload or fly for more than 3 hours straight is not a problem and where cost is a major factor.
So a little less than 3 hours, I'd imagine.
So a little less than 3 hours, I'd imagine.
> I didn't read the whole article
You should have stopped right there.
You should have stopped right there.
A broad torque curve isn't really useful since aircraft engines are already optimized for sustained operation at cruising speed and the range of speeds you can operate at is limited by the propeller and physics. There's no need to have a ton of torque at 1800rpm and at 6000rpm
>At 20 kilograms (45 pounds), the motor can be held in two hands, and it measures only 10 centimeters deep and 30 cm in diameter
And what's the horsepower rating and duty cycle rating on this motor? Power density is not an area where electric motors have a large advantage over ICE unless you're trying to build a cylindrical package. The article talks about doing away with durability requirements that impede a lightweight design.
>with no power-sapping transmission
Most small aircraft are direct drive.
Electric power certainly has advantages but this article may as well be a marketing brochure full of fluff.