France-based VoltAero announced on Tuesday that it has begun flight testing its hybrid-electric Cassio aircraft family from its headquarters at the Royan-Médis Aérodrome. Testing is currently being conducted with VoltAero’s Cassio 1 testbed aircraft, which is powered by two wing-mounted Safran ENGINeUS 45 electric motors, each driving a forward-facing propeller. The Cassio family includes models capable of seating from four to nine people and is aimed at charter and point-to-point regional operations, private owners and utility applications.
“I am very pleased with the testing as we accumulate time aloft and open up the aircraft’s flight envelope,” said VoltAero’s CEO and Chief Technical Officer Jean Botti. “The current test phase is with the powertrain for our six-seat Cassio version, to be followed by validation of the final aerodynamic and powertrain configurations on both the four- and nine-seat Cassio versions.”
In addition to the two wing-mounted electric motors, Cassio aircraft will include a proprietary hybrid power module that combines a 300-kW (402 HP) internal combustion engine with three 60-kW (80-HP) electric motors. The engine will drive an aft-facing pusher prop during cruise flight along with charging onboard batteries. The hybrid power module prototype will be integrated on Cassio 1 following validation on a ground-based testing rig. According to VoltAero, the Cassio family is expected have an endurance of at least 3.5 hours. The company plans to begin deliveries by 2022.
Or just use one Pratt & Whitney PT6A-27 engine as a pusher to carry more payload with less complexity and longer range?
Here we go again. On the basis of a few flights in an old Cessna 337 / O-2, this company is already hawking a “family” of airplanes capable of saving the planet while moving people commercially. And they’re going to begin “deliveries” in just wo years. Yeah … right … I have a bridge I’d like to sell shares in, too. Why is the aviation media so eager to print stuff like this?
I’m STILL waiting for George Bye to bring me my QEC electric powerplant system for my Cessna 172. He was gonna do that about 10 years ago … you never hear of him. Only one eFlyer has flown … where is THAT program?
P.T. Barnum was right … “There’s a sucker born every minute!” Now then … since the French are good at nuclear power, maybe if they’d put a mini nuke in the back that would allow flight forever … THEN they’d be cooking with gas … or is it U-235?
I have always lusted after one of the 195 Cessna 336’s made (fixed gear 337). If the French would build one of those — an e336 — I might have to consider it.
Four engines for long haul?
Seems like a good platform for testing electric powertrains etc.
I cannot see much practical use for it in the commercial world, though. Surely it would be easier to just build a more efficient airframe with ‘conventional’ engine(s).
Hybrid systems have a certain elegance. The internal combustion engine drones along at its most efficient operating point charging batteries while the electric motors handle transient power requirements. It’s a neat way to squeeze high performance out of a small, fuel stingy, power plant. Of course, if the idea is to make kW out of liquid hydrocarbons in flight, then fuel cells represent the optimal solution with Larry’s 336 serving as an interim step.
Suppose the energy density of batteries refuses to follow Moore’s law. Could we see a horse race between them and fuel cells? I hope so because I’m getting tired of the endless prattle about batteries and how they will power the future of flight.
In aircraft, the internal combustion engines usually run at a fairly constant efficient rpm during flight.
Except during take off, climb, descent and any ATC-requested altitude changes. That said, your point is well taken and the longer the flight, the less attractive hybrid electric power would seem.
Retired, I summer near Oshkosh half of the year. Last weekend, I made a quick “checkup” trip up there. I rented a Toyota Corolla in Milwaukee for the four day weekend. The thing sipped gas getting ~ 45mpg in mixed driving. I had a stop to make in Oshkosh where the only Tesla Supercharging stations in the area are located. After dark, I noticed three of the six stations with Tesla’s plugged in so I went over and talked to one of the users. He told me that he goes there after hours because he’s assured of a spot and has no other way to charge his car. So he pays big bucks to have an electric car and then has to waste time in the evening charging his car. Wonderful. But — hey — he’s saving the planet, right … no hydrocarbons are used to generate that electricity, right? Maybe THAT is why Elon shot HIS Tesla into outer space?
Moving backward to airplanes and Mark F’s appropriate comment … why can’t a super efficient turboprop be mounted in the airplane — much like the Toyota example above — so everyone can live happily ever after. And there’s another issue no one talks about. Reliability of ANY system is directly proportional to the parts count within the systems. I concede that — generally — an electric motor is more reliable than an internal combustion engine BUT … with a 402hp piston engine plus three electric engines plus all the ancillary electronics … can that thing fly if one of the wing mounted motors or controllers fails? If not … it’s a piece of junk. And a 337 isn’t exactly one of the most aerodynamically efficient airplanes, either. And — oh by the way — what’s happened to the electric Beaver up in Washington? Maybe George Bye is working on it?
There are SO many things wrong with this idea that my head is about to explode.
The main gear doors were unnecessary; the horizontal tail belonged at the top of the verticals, but the 336/337 always was a fine civil OV-10 alternative. But it was the airport noise champ until the Starship came along. One oversize clamshell airstair door would have been sufficient.
With centerline thrust, it was way ahead of its time. And one of the most beautiful planes that Cessna ever built.
As a sort-of-electric airplane, they could do a lot worse than the Skymaster. I wish them well.
This publicity stunt has no value.
There are many fatal flaws with the concept:
Hybrid cars only get better fuel economy than gasoline cars around town and stop and go traffic. On the highway, its all about the IC engine, the battery and electrics are dead weight that harms economy under these circumstances. An airplane is always ‘on the highway’ and all the electric components slow it down and harm safety reliability and economy.
Reliability is only as good as the weakest parts, so adding more parts harms safety and reliability. When not engaged all the electronics can only harm reliability, just as they reduce useful load and range. The IC engine has to drag them (and the propellers) alone everywhere it goes. The electric motors may help takeoff and climb but other than then they are dead weight.
Also fuel is cheap and plentiful. Especially now so there is no shortage that mandates the need for these contraptions.
I hope most of the frustration expressed here is with promoters who pretend to be on the cusp of bringing something new to market when in reality they are years away. I get it, it leaves everyone in a constant state of disappointment. But I also hope I’m not hearing that research should be spent on simply finding the most efficient fossil fuel aviation power-plant as a cure for the emissions problem.
Look, carbon emissions is a problem and we (the world) need to find ways of solving it without going back in time to horses and sailboats. Encouraging new technologies, concepts and ideas is vital to progress along with accepting failures on a regular basis. There will be lots before we get something workable, but de-riding those who try and invest in different technology is short-sighted. Shifting to greener sources of power, while trying to minimize disruptions to commerce and progress is what most rationale people are trying to do. But,s it complicated – like changing all four wheels on a car while it’s traveling.
I prefer to look at projects like the one in this article and provide encouragement and support for what they are trying to do – which trying to solve a global problem that benefits everyone.
There will be many crazy ideas, silly projects and Rube Goldbergs out there along this journey, but
Carbon emissions from this size aircraft are statistically insignificant, therefore it’s not a problem to solve.
Aircraft are also the worst place to testbed electric drive solution because of the added complexity and costs.
What’s frustrating is that people continue to ignoring reality.
@Jim K, agreed, “carbon emissions is a problem and we (the world) need to find ways of solving it without going back in time”. Yay for innovation. Where I come, it’s OK if most of the innovations fail. That’s the posture that gets the innovations which are truly improvements.
For everyone who says that a hybrid airplane doesn’t make sense, consider this…
Most airplanes cruise at a power setting in the range of 60-80% power. For this exercise let’s go right down the middle and say that the pilot is going to cruise at 70% power. But of course the engine has to be sized to provide the 100% power needed for takeoff.
So imagine propulsion comes from an electric motor that turns the propeller. That motor is sized to provide 100% power, but energy for that motor comes from two sources. One is a gas turbine generator, itself sized to provide 80% of the necessary power, when operating at full throttle or maximum efficiency. The other 20% of the takeoff energy comes from a modest battery onboard that is fully charged prior to flight.
At takeoff, the propulsion motor operates at 100% output. During the climb the power output may decrease to 80% if the duration of climb exceeds the endurance of the battery. If not, then 100% power is available all the way to cruise.
At cruise, the pilot decreases power to the planned 70% but the generator continues to run at maximum efficiency (80%) with the extra 10% going to battery recharging.
If the cruise leg is long enough that the battery becomes fully recharged, then the generator throttles back to produce only the output needed for propulsion.
If the cruise leg is not long enough for full battery charge, then when the pilot reduces power for descent, the generator remains at full output and some regenerative “braking” energy from the propulsion motor can return energy to the battery.
The airplane arrives at the final approach point with enough battery stored energy to support any potential go-around.
The aircraft has a smaller engine than it would otherwise and as a result lower fuel burn and as a result smaller fuel tanks, and so on.
“with the extra 10% going to battery recharging.”
How much is lost in the conversions and transfer?
Very little. Electrical generation, transfer, and storage is very efficient. Better than 98%.
Generation is power take-off from a gas engine so you lose 70% right off the bat. Then the ac/dc conversion takes another 2-3% loss and then the storage losses are around 10% (90% efficient).
Where did you ever see 98% efficiency ANYWHERE when creating & storing electricity in a vehicle?
Hybrid would make sense for a small vertical take off and landing experimental aircraft. Have enough battery on board for 15 minutes of power for eight 40kW electric motors that can be tilted to provide vertical lift. Have a Rotax doing nothing but powering a generator. Cruise at the Rotax engine’s constant power rating with 90% of the power going to forward flight and 10% recharging batteries so you are ready for the next vertical take off after landing.
If only I were not too cheap to play the lottery, I would build one with my winnings…