Tha’s amazing. They were running that project for years and must have spent 8+ digits on it.
I guess the realisation has set in that no better battery tech is sitting on the horizon, and even if there was, you have to somehow charge the thing.
I met face to face with the X-57 people from NASA several years ago, they were evidently talking to anybody involved in their field. I won’t comment on that meeting specifically but I’m not surprised at the outcome of the program.
I’m asking this question with close to zero engineering knowledge.
Would the motors attached to the front of the wing not make the airflow over the wing very turbulent? Isn’t that the exact opposite of what you want? Isn’t that likely to lead to stall like behaviour as the airflow isn’t attached to the wing?
Given that the NASa programme was constructed around the Tecnam P2006T, I suspect these two events are linked
Would the motors attached to the front of the wing not make the airflow over the wing very turbulent? Isn’t that the exact opposite of what you want?
What do Vortex Generators do to the airflow over a wing? Blown lift is obviously more complex than that but there are other issues regardless with reducing the wing area dramatically and relying on blown lift for low speed flight. Also with putting the main propulsion motors on the wingtips.
Cobalt wrote:
we have finally figured out what was obvious all along because, physics.
I’m not arguing with Tecnam’s decision that it doesn’t make commercial sense to pursue electric propulsion right now, but I’m intrigued by your comment.
Do you mean to imply that there is some law of physics that limits battery energy density?
Obviously not, but the airframe makers who were pouring millions into that stuff are not the battery developers, and the latter have not come up with the goods despite absorbing countless millions also.
With electric cars being a multi billion $ business, one would think the issues would have been pushed out by say another factor of 10, but this has not happened. I recall a meeting with one car battery specialist who said they can get 5x more capacity but the battery then lasts only 10 cycles 
So every time they discover something, it turns out to be impractical, one way or the other. The known low hanging fruit has been picked.
Also once you get batteries which are just-ok for cars the business case for pouring billions into making them better disappears, because there is no other mass market (nobody seriously thinks electric planes are a good idea). Trucks need so much energy that you are up against charging viability.
The other factor which is stopping vast battery R&D funding is that most people cannot possibly operate an electric car (nowhere to charge it, etc) so the current expectation is that the market will tail off in a few years’ time.
Aviation was always hanging its coat on the hook of electric car batteries…
Airborne_Again wrote:
Do you mean to imply is some law of physics that limits battery energy density
Of course there is. Well, it is actually chemistry which is the limiting factor for battery energy density. Huge amounts are spent on finding chemistries that can be used in rechargeable batteries and on making them work in practice. We are quite far away from theoretical limits, though.
But I meant something different – I meant that because of the physics underlying flight it is hugely weight sensitive, and the current battery technology is SO far off the mark that any viable electric aircraft needs a massively (no pun intended) lighter battery technology which simply isn’t on the horizon.
That does not mean that it will never happen – but just imagine someone developing electric cars when the best available battery technology is lead-acid. You get milk floats (10 mph boxes with 50 mile range) trying to compete with proper cars. It needed Lithium based batteries to get to “proper” cars
Not quite @Cobalt research Lucas EV programme back in the 70’s and 80’s.
Ogilvy even designed an electric taxi based on their system as well as Bedford electric vans used widely in and around London by various government departments. They were demonstrated in Paris and able to go much faster than 10mph and had much more than a 50mile range.
They used a lead acid battery pack (lucas manufactured of course) contained on a metal tray. The tray was mated with the vehicle underside using a pallet lift and removable bolts.
It took 5 minutes to remove one battery pack and replace with another. The original pack was then hooked up to a charger and the vehicle just went on its way. That was lead acid batteries, imagine what could have been achieved with todays batteries.
@gallois but your example involves pack swapping.
It’s been shown time and again that pack swapping only really works for a fleet operator with a fleet of a certain minimum size, where the fleet never goes too far from the depot and returns to it routinely anyway. You also need to dedicate space and staff to the pack swapping operation, and continual operation requires likely twice as many packs as vehicles.
Breach any of those requirements and it falls apart straight away.
