January 17, 2025, ©. Leeham News: We do a Corner series about the state of developments to replace or improve hydrocarbon propulsion concepts for Air Transport. We try to understand why the development has been slow.
We have covered why the technical progress of battery-based aircraft has been slow. Now we look at what type of missions it can do this decade and beyond and why the limitations.
Figure 1. The Diamond eDA40 electric trainer. Source: Diamond.
After covering all the problems with batteries used in eAircraft and eVTOLs, let’s see what mission types these can do today and tomorrow.
Battery-based general aviation aircraft, from the Pipistrel Velis Electro to the up-and-coming Diamond eDA40 trainer in Figure 1, are suitable for base pilot training, whether for private or professional pilot training.
A well-designed battery-electric trainer is easier to prepare for flight than a thermal engine aircraft. There is no engine to check and no fuel to handle and check. Checks of the electric system can be done from the cockpit on a big screen display. It’s also virtually noise-free compared to the thermal variant and puts out no direct emissions around the airfield.
Its drawback is that it has a maximum mission time of about 45 minutes when operating with VFR flight reserves. Thus, it’s not a training aircraft beyond basic training and can’t be used for IMC (Instrument Meteorological Conditions) or multi-engine training, as this requires longer missions in varying weather conditions. It’s, therefore, only the initial aircraft for any pilot syllabus beyond a VFR private pilot course.
A major limitation is that all eAircraft to date will be certified for VFR and no Flight-Into-Known-Icing (FIKI). The same restrictions apply to all eVTOLs that are developed, with the difference that practical mission times are here less than 25 minutes.
How long will battery-based eAircraft and eVTOLs be limited to mission times below an hour, and thus, as these typically have less than 130kts cruise speed, to missions of less than 100nm?
The OEMs promise better battery cells before 2030. Given what was covered in the last Corners, this will not change before 2030. The hope is that the car industry will have enabled solid-state battery cells by 2030, increasing battery capacity and safety.
When will battery cells be available at the correct cost level to increase battery capacity so that eAircraft can fly the typical commuter aircraft routes of 200 to 300nm and still have reserves ample enough for real bad weather situations?
I would say between 2030 and 2035. This is when battery-electric small commuters will have a business case, starting with the nine-seaters, as these can operate with a single pilot (it’s very difficult to amortize two pilots on an average load factor of seven tickets).
Will larger aircraft than nine-seaters make sense as battery-only eAircraft? Probably not. There is not a single project left that projects 19-seaters or beyond that is not looking at hybrid setups or hydrogen fuel cell alternatives (we will look at these projects in coming Corners).
What about the eVTOLS? Until the battery technology changes at the end of the decade, the only reasonable business case seems to be the airport-to-city-center shuttle. Given that the present eVTOLS are VFR day only, with only the Joby certifying for VFR night conditions, their capability to replace helicopters is limited.
It must be for distances below 15 to 20nm and benign weather conditions year-round. I have such a case close by (I’m based 10 minutes north of the Nice airport). Landing from a flight at Nice airport and taking a taxi or Uber to Monaco is best case 45 minutes and worst case a 90 minutes ride.
A helicopter flight is 10 minutes from Nice Airport to the Monaco Heliport, and the present pricing is 200€ per ticket. Given that taxis will cost you 100€ it can be worth it. There is, thus, a market with at least two companies operating the route at present.
So, the Nice Airport to Monaco is a good example of where an eVTOL could offer a quieter, more environmentally friendly alternative (the helicopters are noisy when landing at the Monaco heliport, and apartment buildings are next door).
But the example also shows the limited market available before the operational utility of the eVTOLs increases with longer practical endurance (including reserves for that “shit”-day), IMC and FIKI conditions, etc.
There aren’t many Nice-Airport-to-Monaco with VFR weather year-round. This means that the eVTOL market will expand at a modest pace initially until its operational utility allows it to replace helicopters in more use cases.
You have some more suitable eVTOL routes out of SFO (to Palo Alto, Sunnyvale) and LAX (like Santa Barbara) using the good California weather. LA traffic jumping is another (Like at El-Traffico fotball games). Boston is another during good weather conditions. The military is another delivering cold beer in hot areas and picking up casualties/troops on rotation.
As soon as US troops start using them UK special forces will come up with multiple now unthinkable applications.
I am no Nice expert, but I have had some doing with LA. Right now they have major fires that the Santa Anna winds got ahold of. Those winds are 85 mph. Now the smoke is not normal but the winds are.
In the Winter, LA can be hit by atmospherics hoses, basically a string of lows coming in off the Pacific. So you have to build into your model the worst case of winds and fronts. Free shuttles can take you into many location in LA though Taxi if a non business area.
Certainly anything on the edge of LA would be non feasible range wise.
My experience is snow removal. Some winters like the current one, almsot none. Some it snows upwards of 130 inches. Its a boom and bust business. Commercial ops will do a blend of fixed payments and so many snow events.
One year at the airport we had no snow until early spring (for most that is winter). Then we got dumped. When the contractor called his snow people, only 30% responded, the rest had drifted off.
Contractor got reamed but FedEx also realized they needed to add a fixed payment to the contract and write into the contract that they do weekly callouts and fill missing positions.
Same for heli ops and more so electric heli ops. You better have the worst case baked into the calcs, or it will bite you.
Bjorn has extensively covered e-VTOL technology for us, including ATC, piloting, battery, urban safety realities, certification and business cases.
As far as I can see those realities haven’t changed much over the years. Battery capacity is growing slowly, promised breakthroughs are constantly pushed back into the future. And authorities stick to their safety requirements.
Still techno optimism, e.g. the great batteries from 2030, supported by great graphic visions keeps on managing public expectations.
I think battery capacity will keep improving slowly & authorities will remain strict. Thus most E-VTOLS will most likely be unmanned, militairy or used for expensive niche applications.
The real competition for all flying taxis I’ve seen so far are electric cars door to door, all weather, 1-9 people with lots of luggage at a fraction of the costs / energy. You can even “fly” them yourselves at night while making hands free calls & listening to Beethoven & then land them under your downtown hotel in stormy weather.
keesje:
We are on the same plane on this one!
One exacmple comes to mind is my almost 6 ft wife, her nice (also 6 ft) and her boyfriend at the time also 6 ft and all their lugged going 220 miles South in the Passat (diesel)
Around 5.5 gallons of fuel for that run!
keesje,
Don’t forget (not that) far, far away, it’s estimated ‘the scale of the country’s low-altitude economy at more than.. [$93 billion] this year, with projections to exceed 1 trillion yuan by 2026. This year, for the first time, the term “low-altitude economy” was included in the Chinese government’s work report’
There is some progress with hydrogen fuels cells in combination with batteries as you save mass and can use smaller battery packs, still LH2 or H2 composite pressure tanks at vertiports are limited today.
And it keeps being pushed 10 years into the future.
I am in full agreement to experiment with and research the area, but you sure do not want to put big bucks into it, you are going to be very very very disappointed.
Electric auto drive cares have their issues as well. They have to be able to function in rain and fog.
Winter cities are impossible.
Having lived and flown in Southern California I can tell you that the morning weather along the coast until the fog burns off is IMC well until after noon for a good part of the year. So the idea of SoCal being a home for early e-vtol VFR ops is a fantasy.
I did not scroll down to see your response.
I ran into the fronts for planning purposes and the winds, I know about fog in Ca but not LA specifically.
Phoenix some winters comes to mind as maybe New Mexico but those also get that South East Typhoon season that some years is a regular drenching.
they do avoid the Marine Layer (grin)
Unless your Flight School is out of a city, 45 minutes is far to short to get to a training area.
Metour pilot did a nice one on that.
I don’t see the fuel and oil checks as a plus or minus (more accurately so miner as to be a non issue). You are going to do a walk around and at least lift the lid on the motor and check for anything obvious.
When I trained, they topped up the C-150s with fuel at night and they had two training flights time easily for the next day. Your Pipesel is going to need to have a battery charge.
The Pipesel is very crowded, so your flight instructor/student combo is going to be limited. While you can try to adjust that, its not always possible. We had one very large flight instructor who got paired up with a professional football player. Between then and full fuel they over grossed a C-150. Even with our smallest flight instructor it was a bit marginal. They moved over to a C-172 (he could afford it and it got them more room individually and as a pair)
I have a Battery powered lawn mower, its fantastic. More than enough battery to do t he full lawn in one go. A big enough lawn and you need more AH battery or more batteries. It has a limit though its a fantastic case of elecric working beautifully.
What is the efficiency difference between:
1. Fuel Helicopter vs Electric? (ie the fuel weight going down is going to factor in). Almost any e flight is going to need to charge before it can return I would think.
2. A fixed pitch electric vs an electric helicopter
3. A fixed pitch 4 place airplane (C-172) vs a 5 place Electric Helicopter
some examples:
VW Passat B8 : fuel fraction is 2.5%
C172 : fuel fraction is ~15%
Bo105: fuel fraction is ~20%
impact of fuel fraction really only hits on longer range airplanes.
fuel fractions also hint at where BEVs make sense though.
OT:
afaics a hybrid “taxi”helo makes sense. E+IC Power for hover and take off, IC (efficient diesel) for cruise and charge.
Hi Bjorn
Does the helicopter or eVTOL service get you from Nice airport to your front door, with your luggage? – like the car taxi does.
Isnt this is going to mean, flight to Nice, eVTOL to Monaco, taxi to home?
Is the hassle of the additional hop going to actually save time, and somehow be less painful overall?
From an environmental stand-point, eVTOLS use a lots of energy/ electricity to move stuff from A to B, compared to alternatives.
Reality is that most of the precious electricity used isn’t sustainable generated at all.