5 things I learned at the AERO show
Friedrichshafen, nestled on the banks of Lake Constance in southern Germany, is no stranger to aviation innovations. This picturesque town is best known as the birthplace of the Zeppelin, a huge flying ship that once promised to revolutionize air travel. While the future of trans-Atlantic air travel turned out to be both less glamorous and more practical than Count Zeppelin imagined (I’m writing, as I return home, on an iPad connected to WiFi at 36,000 ft. over Greenland, after all), the city retains a reputation as the place to see exciting aviation ideas in action.
Last week it showed why in hosting the annual AERO show, a weeklong gathering of pilots and aviation enthusiasts from across Europe. What was once a regional exhibition of ultralights and gliders has grown into the premier general aviation show in Europe. It boasts a diverse and interesting mix of airplanes, with a focus on emerging technology.
For a crass American, this is a very civilized show, held in a beautiful convention center with great coffee and lively beer gardens. Oshkosh this isn’t. Beyond these mundane differences, though, AERO offers a fascinating lesson for US pilots. If all you’ve heard is how awful things are for private pilots in Europe, let me offer a more complete – although not entirely rosy – portrait.
1. Electric airplanes are coming. Yes, and free beer tomorrow, you may say. Well, electric aviation may be a bit of a sideshow in the US, but it is clearly the future of light aviation in Europe. Faced with expensive (sometimes nonexistent) fuel and ever tighter environmental rules, there’s little choice. Engineering giant Siemens had a large presence at the show, displaying a Pipistrel with a hybrid Rotax/electric propulsion system and a stunning Extra 330 aerobatic airplane with a fully electric front end. The battery life is severely limited for now, but it’s probably enough for an aerobatic routine (the idea with an Extra) and a one-hour training flight can’t be that far off.
One intriguing possibility, at least in the US, is that electric airplanes could sneak past diesel as the “next generation solution” for avgas’s eventual disappearance. Diesel engines are far more proven, but they’ve been slow to gain traction in the US, where 100LL remains available and relatively inexpensive (no, $5.75/gallon is not outrageous). Retrofits from Continental are pricey, and the operating economics simply aren’t persuasive enough to justify the initial outlay.
Electric, on the other hand, could offer a more dramatic change. One concept on display at AERO that’s particularly interesting is an electric ultralight with a quick-swap battery. With this, a flight instructor could walk out to the airplane with a battery for the next lesson, then bring it back in to charge while the next instructor takes another battery to the airplane. Developments like this, which will benefit from the billions of dollars being invested in electric cars right now, just might make electric a reality for flight schools. For your King Air? Probably not yet.
2. A focus on recreation. One reason electric airplanes get so much attention at Friedrichshafen is that GA fulfills a very different mission across the pond. Piston airplanes are for fun, and very little attempt is made to justify their worth based on utility or travel plans. Few European pilots have an instrument rating (less than 10% by some measures) and night flying is likewise rare. Maybe the 120 mph autobahns and the shorter distances between cities make airplanes less essential, maybe the aforementioned high price of fuel makes it uneconomical, but the result is an industry that’s quite focused on fun flying. This may be disappointing to some American pilots, but it’s also refreshing in a way.
Because of this recreational focus, and because of less stringent microlight laws below certain weights, a small but active sport airplane industry has emerged. It’s filled with companies Americans have never heard of and sometimes-odd designs. A single exhibit hall at AERO showed off a wide array of gyrocopters (including one for medevac use), an L-39 fighter knockoff made entirely from carbon fiber, and the fascinating, all-electric Volocopter. I don’t need to fly all of these strange creations, but the creativeness and hustle of these small firms is more than a little inspiring.
3. European airplanes have more style. No offense to Cessna or Piper – I consider the 172 to be the best airplane ever made – but some European airplanes make traditional US designs look like flying bricks. With their sleek canopies and swept wing tips, there’s clearly an emphasis on aesthetics in addition to aerodynamics. Sure, those low drag details serve a practical purpose when weight is limited and fuel efficiency is paramount, but I also detected a lot of pride in their “ramp presence,” as the salesmen say. What should we expect, though, from the people who invented the Porsche 911 and the BMW M3?
Are US manufacturers wrong? Actually, I don’t think so. As sexy as those two-seat airplanes from Eastern Europe look, they aren’t all that practical for Americans. For one, they’re small on the inside: two healthy pilots from Texas wouldn’t last long in the cockpit. Secondly, some models had a worrying lack of detail when it came to discussions about maintenance (remove the entire cowl for a borescope?). All airplanes are compromises, and I suspect our priorities are just different.
4. Certification reform is the topic du jour. At the same time we debate the merits of an overhaul to the FAA’s Part 23 certification process, Europeans are grappling with a major update to EASA’s CS-23 rule. This is not accidental: one of the major goals of the reform movement is to synchronize international standards and procedures. Hopefully this makes it less expensive for new airplane designs to become reality, no matter where they are made.
As with any change, though, it’s not as simple as changing the rules and moving on. At a panel discussion about the proposed CS-23 changes, pilots simultaneously applauded and criticized EASA. They seem to be making a genuinely good faith effort to knock down barriers, but the process has been long, confusing and just a touch opaque. As Ian Seager, publisher of the UK’s Flyer magazine observed, getting 28 different national aviation regulators to agree is almost impossible. It was almost enough to make me appreciate the FAA. Almost.
5. We take a lot for granted in the US. Before you tell me to move to Europe, let me assure you that AERO also reinforces just how good we have it in the US. We talk about the free Air Traffic Control services a lot, and pilots will often grudgingly admit that the free ADS-B datalink weather is nice. Both are truly special – I spoke to many pilots who would dearly love ADS-B weather in their airplanes. One luxury I hadn’t considered was pilot-controlled lighting. This is an afterthought for most American pilots, available at even the quietest country airports, but it has only recently become legal in the UK. It’s still exceedingly rare.
The FAA is bureaucratic, Congress pours fuel on the fire, and too many municipalities try to close general aviation airports. Having said that, there’s a reason European pilots come to the US for training, experience building and fun flying vacations. We’ve simply got the best aviation system in the world. Admit that next time you feel frustrated by the length of the FARs.
A German proverb cautions that wer rastet, der rostet: “He who rests grows rusty.” To me, it’s an appropriate reminder that, while the United States has enormous advantages for private pilots compared to Europe, such advantages are not pre-ordained. That means we must fight unnecessary regulations, but it also means our industry needs to keep its eyes on the future, not the glory days. We could take a cue from the scrappy, creative companies at AERO, who, though faced with often overwhelming government limitations, churn out sexy, efficient airplanes… And put on a great show.
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I think the European focus on recreational flying is well placed. I would guess that probably 80 – 90% of the pilots do not need and cannot actually use the transportation capability that the typical U.S. manufactured airplane is capable of. I would point to the popularity of Van’s RV series (and other small homebuilts as well) as evidence that recreational flying is popular here also and that these types of planes are much better suited for that than the typical Cessna or Piper. Our recreational planes just tend to be a little bigger (and noisier) than the European versions because of the tax structures and noise laws. As you point out, this is something to watch out for; unless we want to be like Europe. Maybe that is a desirable option, I don’t know. Most of the comments I’ve seen coming from Europe indicate that their situation is not all that desirable.
John, you covered that topic well. I was especially interested in the rapidity of the decline in GA airports, courtesy of our political machines, both local and national. At the same time, these same politicans would never get to meet their constituents, (their employERS,) if it weren’t for those small and local airports. At the same time, the vast expanse we commonly travel around this continent, (as opposed to Europe,) actually makes the “electric airplane” kind of impractical, at least for the moment.
All in all, a well written, and accurate, article. Thank you Sir.
I found this article to be interesting. My wife and I have been looking at moving to Europe either part time or full time after I retire. I’ve looked into flying when I get there and it simply looks to be prohibitively expensive. Gliders might be an option. Personally what I’d like to see is an electric motoglider.
You are right, you don’t really want to pay for AvGas here. Fortunately thermals are free and gliders are a lot of fun.
You may want to take a look at this
Great Article John, with one small point of disagreement. Your comment about the eastern European sport planes being small on the inside. When I started Flight training in 2012 my future instructor had me sit in a cub, a 172 and a Pipistrel Virus. I am a 6’2” 225 pound Texan my instructor was a little larger than me. I wound up training in the Pipistrel in part because it seemed roomer on the inside than the American planes. I suspect that like European sports cars, once you are in the airplane you realize there is more space than seems possible from the outside.
Airplanes are essentially time machines that shrink distances by shrinking the time requirement. That is the reason we fly: to get from point A to point B where the distance between the two is great enough that the speedy element of flight comes into play.
Battery powered electric airplanes just cannot carry enough energy (fuel) to get from point A to B. It’s just a plain and simple fact of the law of nature. Consider this:
Energy Type Energy Density by Weight Energy Density by Volume
Jet A 42.8 37.4
100LL 44.0 31.59
Lithium-ion Battery 0.875 2.63
Lithium if ignited 43.0 23.00
From an electrochemical point of view, there seems to be little promise of ever approaching the energy density of gasoline and kerosene. And also, Jet A and 100LL only represent the mass and volume of part of the fuel, since the remaining portion of the fuel comes from the oxygen in the air that does not contribute to the weight or volume of the energy system. Basically the air to fuel ration is about 15 to 1. So you can see that only about 1 part of the 16 parts of the energy in a gasoline or kerosene powered airplane is carried in the vehicle. A battery must carry the full complement of it’s energy load, which means there is a further weight and volume penalty from battery powered systems. This is why battery powered vehicles are essentially a mass of electrical battery cells connected in series.
I have also included the energy from oxidation (i.e. the burning) of lithium. If you burned lithium you could extract about the same amount of energy by weight as you get from JetA or 100LL. And this also tells you that lithium battery fires are significant concerns and why the airlines are having issues with the transport of this type of battery. They are dangerous. As more electric cars get into our highway system, we may become aware of just how dangerous this technology can be.
A far better solution is the fuel cell. In this process the electrical energy (electron flow or current) is produced by an oxidizing reaction. You don’t need to carry the oxygen as it comes from the air (just like gasoline and diesel fuel) which is a significant benefit. And the fuel cell process if far more efficient than the thermodynamic Otto cycle which wastes over 50 percent of the energy as heat. The fuel cell can reach 90 percent efficiency.
This is where the DOE should be putting its focus. Not on batteries, but on fuel cells.
You present some good engineering data for comparison sake – being an engineer this is how I look at stuff too. I agree with you that current commercial Li ion batteries have relatively low energy density compared to fossil fuel, and that the range of current model battery-electric aircraft is limited to about an hour (with one new exception). I also like the concept of hydrogen fuel cell vehicles and their inherent higher range performance. However, there are some other factors your analysis doesn’t consider.
Energy conversion efficiency – all internal combustion engines suffer from poor energy conversion (fuel to wheel, or fuel to prop) efficiency, generally only 25-30% of the energy content of the fuel is converted to mechanical drive energy. Most of the energy in the fossil fuel is lost to waste heat when its burned.
Modern lithium ion batteries have electrical efficiency (electrical energy out divided by electrical charge energy in) that is >99%. The mechanical conversion of electrical energy in to mechanical energy out by electrical motors is also very high, with typical efficiencies of 85-95%. So the combination battery-motor efficiency is also about 85-90%. Meaning the to put the two motive systems on an apples to apples basis, you’d have to divide the fossil fuel system by a factor of two to three. Electric motors are also much lower weight than IC engines, with Siemens announcing last year a new 350 hp electric aircraft motor that only weighs about 100 pounds. So you have to look at the combination fuel + engine weight, not just the fuel weight, in comparing the technologies.
Emerging battery technologies – new technologies are being developed and commercialized now that provide huge increases in energy density of batteries, including lithium air batteries and others that involve new synthetic anode materials that are much lighter weight and allow much higher energy weight densities, tripling or more the energy density of current commercial batteries.
There is already one new battery-electric aircraft announced recently that advertises a duration of approximately 3 hours of flight time. And that’s with just standard lithium ion batteries, not the latest tech stuff as described above. Quick charging is also being achieved, with the ability to recharge a vehicle or aircraft battery in as little as 10-15 minutes, which is equivalent to a typical fuel stop duration for our current avgas planes. Conceivably within the next couple of years we could see aircraft with durations of as much as 5 hours of flight time, and a short recharge timeframe.
Practical all electric aircraft technology is not as far off as some – including me – have assumed until now.
Duane, you are correct about thermal (heat engines) being much less efficient than electric motors. As an EE, we learned that electrical power systems are typically way above 90 percent efficient. Very little waste heat is generated compared to internal combustion power systems. I my original post, I mentioned that the Otto cycle (piston engine) is less than 50 percent efficient. But even factoring in this energy loss, the net energy density of hydrocarbon fuel based piston or jet engine system is something like 20 times better than a 100 percent efficient battery-electric motor system. It’s all in the chemistry of batteries. The battery can be very efficient, but the question is how much energy can it store? With hydrocarbon fuels, the air needed for combustion is not part of the weight or density calculation. This provides another significant plus for hydrocarbon systems. Much of the energy is stored in the air as well as in the fuel. Last, I mentioned the fuel cell, because this represents a chemical reaction in which the air is “burned” or the fuel is oxidized and the electron transfer of this chemical reaction is captured in the form of electric current. The air comes from outside the system so there is no weight or density penalty. There is probably more heat thrown off in this reaction versus an electrochemical reaction of a battery, but the amount of electric current produced for the amount of fuel consumed (by weight or volume) should be much more than a battery. So this is why I think the focus should be on the fuel cell. It produces current so the heavy piston engine is replaced by a lighter weight and more energy efficient electric motor. The problem is I don’t know how compact and light they can make a fuel cell. Boeing and the military have been doing flight testing with fuel cell powered aircraft; a few manned tests have been done, but the current emphasis seems to be UAVs.
There hasn’t been much developmental work on fuel cell aircraft yet that I know of, but there’s been a lot of work on car motive systems, and the same technology can theoretically work just as well in an aircraft.
Honda has been producing fuel cell vehicles (FCV) for more than a decade, and about every 3 years they have been bringing out a new and improved model of their “Clarity” FCV. The principal improvements have come in the fuel cell “stack”, which is the physical reactor where the stored hydrogen and oxygen from ambient air are reacted to produce electrical energy and plain water exhaust. The most recent Honda model increased the “power density” (kw-kg) of the stack by something like 50% over the previous model. The fuel cell stack in prior models of the Honda Clarity had to be placed in the rear trunk due to the volume, but the new model places the stack under the rear seat. It’s about the size of a small desktop computer tower case and weighs less than 200 pounds.
The other area of progress is in compressed hydrogen fuel tanks. Much of the weight of the fuel system in a FCV is the weight of the empty tank, which must have very thick walls to withstand internal pressures of thousands of PSI. New advancements in carbon fiber materials have allowed the tanks to become much lighter. The weight of the compressed hydrogen itself is almost insignificant. A few kg of compressed H2 can power a car for hundreds of miles of range.
We can expect these improvements to continue with each generation being approximately 50% more efficient in terms of volume and weight than the prior generation. Sort of like a decent fraction of Moores Law (i.e., where transistor density doubles about every two years in new model semiconductors).
Other manufacturers are also competing with Honda, including Toyota, Mercedes Benz, and likely others will too. I would say within a decade or less we will see application of fuel cell technology to light aircraft.
CORRECTION: The table that I presented in my prior comment got squished together:
Here is a replacement that should be easier to read.
Energy Type__________ Energy Density by Weight____Energy Density by Volume
Jet A _________________42.8____________________37.4
Lithium if ignited_________43.0____________________23.00
Jack, I can’t argue with your math, and I’m hardly a lithium-ion booster. However, I think we might disagree early on in your comment. You say that “That is the reason we fly: to get from point A to point B.” I’m not so sure about that. Sure that’s true for the Cirrus owner or the TBM owner. But for a flying club member who takes the Cherokee out for 0.9 hours on pretty Saturdays, it’s a completely different mission. And the number of these pilots is significant – more than half of GA pilots by most estimations.
That’s the lesson (for me) from Europe. The vast majority of pilots in Europe aren’t interested in flying for transportation. It’s about pure recreation. For that crowd, electric may be more practical than you think.
In response to your well reasoned comments on my post to your original article:
I am a co-owner in a Cherokee 180, that I have twice flown round trip across the USA. Most of my non training flights involve distances in the 100 to 350 nm range with friends and family. I don’t see much value in flying an electric powered plane with a range of 1 hour or less. This would really limit my utility and force my flying to be mostly pattern work.
If GA flying transitions to short (less than 1 hr) flights as you indicate, I think its utility becomes mostly a hobby and maybe that’s where we are headed. But if so, I fail to see the point of GA being a viable method for transporting your family and friend. It is sort of like boating becoming limited to canoes and kayaks. Yes some people would be happy with that, but many more enthusiasts would be turned off and the net effect would be a loss overall.
By understanding which sources of energy provide the best potential for powered flight, we can progress to the future. (Except in engineering classes, we don’t teach this so the populace at large is in the dark, if not outright misinformed.) The laws of chemistry tell me that the battery is not the way to go (it is a dead end) in the future because it cannot deliver enough energy per unit of mass or volume to compete with existing piston and jet engine powerplants. I don’t know if fuel cells can be made light and compact enough. But on paper, they can deliver far more electrical energy from fuel by weight than can be stored in a battery by weight. I am puzzled why the government seems invested in batteries, windmills, and solar cells, but not in fuel cells. Could the answer be more political than technical?
It is very difficult to work the numbers and come up with a viable 0.9 hour flight time in a reasonable performance electric airplane. If we are talking a powered glider then perhaps, but something roughly in the performance range of a Cessna 152, or other trainer, not so much. The chart presented above that shows LiPo batteries at an energy density roughly 1/50th that of diesel or gasoline tell the story. You cannot simple change all the laws of physics to make a practical airplane that requires 50 times the mass of energy storage or present aircraft.
As an example: We take a basic small trainer and say we are ok with a flight time of 1 hour, plus 45 minutes reserve for contingencies (field closes, lots of traffic in the pattern, weather, etc.) That fuel load in a very small trainer would amount to at least 50KG, 110 lbs. Now multiply that by 50 times to get the mass of the battery required and you see how impossible this becomes. Even if we say the electric plane is 3 times more efficient due to the electric motor vs the diesel engine, and we can accept 1 hour total flight time (no reserve at all) we end up with 10 KG of fuel or 500KG /1100 lbsof battery, completely impossible to lift off the ground.
Electric cars work, even the Tesla with it’s 300 mile range, because cars don’t have to carry their own weight. A Tesla battery weight roughly 1000 lbs which does make the Tesla very heavy in spite of it’s aluminum construction but the Tesla carries this weight on ball bearings, not with induced drag producing wings.
Viable, affordable, mass-producible fuel cells have been, as Jerry Pournelle would say, coming “Real Soon Now” for going on about eight decades, and over a century if you count the relevant early electrochemical experiments that proved the _possibility_ of the technology. NASA has been using them quite happily (well, ignore the poking of both of Murphy’s eyes with a mission actually named Apollo 13! ;) for approaching six decades, but that fact alone should clue you in as to what the problem is: cost. I can’t believe that you and John, purportedly both engineers, forgot that, as engineers, we were required to take economics in order to earn our degrees. That’s because, unlike scientists, we have to deliver products (and don’t forget services, such as getting from Point A to Point B, or Just Having Fun) _within_a_very_firm_schedule_and_a_budget_ (unless you’re a government contractor, especially a military one, and worst of all, in aerospace!). Heck, the scientists don’t even know if they’re even proposing something possible, let alone economically feasible, if they’re doing their jobs right! Fuel cells seem so brain-dead simple, and so many teenagers have demonstrated them at science fairs that almost everyone is scratching their heads as to why we haven’t been using them in every mode of transportation for the past 50+ years.
The other word that is lacking in an appalling number of supposed engineers’ vocabulary is the M word – Manufacturability. Being able to make one of something in a lab (or, increasingly, kitchens and bathrooms!) in no way translates to being able to make thousands, and especially hundreds of millions, of that something. Automobiles and electric lights were around for decades as hand-built curiosities until Ford and others came along and figured out how to turn such quaint craftsman-powered, cottage endeavors into actual industries (“cottage industries” is an oxymoron, emphasis on the moron part!). If you ever want to see a grown man cry, talk to a chemical engineer sometime about a regulated industry (for very good reasons) that is still closer to alchemy than what you spoiled EEs get to do, with all of your “clean” technologies (Oh, many Superfund sites are so designated because of semiconductor, transformer PCB, and many other electrical/electronic manufacturing toxins just being poured on the ground and into our waterways? Oops! ):
The hydrogen in fuel cells has to come from somewhere and it has to be _safely_and_economically_ stored in a moving device that can be going at literally astronomical speeds (well, at least for NASA, the ESA, et al). Remember that energy increases by at least the square of velocity and you begin to understand the problem for those poor schmucks having to sign on a dotted line that their design isn’t going to bend, fold, spindle, mutilate, or kill anyone in or around said transportation device.
Batteries have simply crossed the manufacturability chasm because we’ve been making them for computing and communications products at the truly massive economy of scale level of billions, soon to be tens of billions, of cells manufactured. The manufacturing of a vehicle/aircraft cell is at roughly the same unit scale as in a mobile electronic device battery, while fuel cells aren’t. Also recall that early automobiles were actually electric-powered, and that infernal-combustion engines made short shrift of the electric competition in terms of speed and range. However, that’s when the fuel was literally dirt cheap, coming out of the actual ground. As for those nasty pollution byproducts … they were insignificant when only the wealthy (not even the rich) could afford them (an NBA or NFL player can be rich – an NBA or NFL team owner is wealthy!).
The continents-sized tug-of-war being waged in the energy minerals extraction businesses is going to be with us for a very long time when you consider the recent discoveries of proven fuel reserves off the coast of Brazil, in the South China Sea (hence new Chinese “islands”). That’s on top of the immense productivity yield leaps that fracking and horizontally-directed drilling have made possible, not to mention the discovery of potential new fuel reserves via high-performance computing using data gathered by advanced geological sensing technologies.
Until your mobile electronic devices all come with fuel cells, don’t hold your breath waiting for them to appear in your car or aircraft. If fuel cells were the answer, Elon Musk would be using them, and he’s not, at least not in his terrestrial vehicles – SpaceX is, though – on federal aerospace contracts … Hmmmmm …
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