By Bjorn Fehrm
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.
Operational utility of battery-based eAircraft and eVTOLs
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.
Longer flights than an hour or 100nm?
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).
eVTOLs
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.
Related
