Eviation Alice (Electric Regional Airliner)

I'm not too suprised...

However, I'm convinced they are not going into certification which an highly complex design as originally inteded.

BTW you might believe or not and it is just "whisper mail", but a friend of me talked to one of the Lilium embloyees. I wan't tell his job, because he might loose it if I do, but in his position, he definately knows the capabilities very well. I said, that they archieved very much and made a lot of progress with the controls an/transition, high speed etc. but they need to wait for better batteries...

The good old battery problem...
 
www.flightglobal.com

Eviation’s electric commuter aircraft undergoing ‘subtle’ redesign

The Washington-based developer maintains that the adjustments will be minor and that the aircraft's timeline for certification and service entry remains unchanged.
www.flightglobal.com www.flightglobal.com

"Eviation confirms it is making “minor changes” to the dimensions of Alice’s wings – including both thickness and span – and adjustments to the contour of the fuselage “to improve the manufacturability of the aircraft”.

"The electric aircraft developer adds that it will complete wind-tunnel testing later this year and complete the new configuration’s design early in 2024. It still aims to start certification test flights in 2025"

So all of next year will be spend designing and building what will hopefully be the final production conforming version to start the long and arduous certification process. But tinkering around with the wings and fuselage doesn't solve the biggest issue of all, which is relatively poor range caused by low battery density. Not to mention the hefty weight of the battery itself, which is a whopping 8,000 pounds.

"But Markham told FlightGlobal on 26 September that the carrier is not committed to Alice as a mainstay of its future fleet."

“We are open to having conversations with other manufacturers as well, whether it’s all-electric or a hybrid-electric option,” she says. “Certainly, [Eviation] was the first to approach us… but I think there could be a horse race.”

So even Cape Air is now distancing itself from the idea that they are going to operate a large fleet of these aircraft. The only aircraft that would have been perfect for them was the electric version of the Tecnam P2012, but the manufacturer pulled the plug on that project and was honest enough to admit that the battery tech was simply not advanced enough to make the aircraft economically viable.
 
Last edited:
I wonder what all those terabits are worth when flying around without even retracting the gear. Probably all the information was, it is by far too risky to fly it a second time...Very likely, the wet hands of the pilots was all they needed to know...

I'm not an aircraft expert, but I guess with some experiences in aircraft design (maybe by building model planes), the plane would have had less problems and could have even used the originally intended runway…

Thanks God, some external proffessionals are doing the ongoing redesign!
 
We don't know for sure but it seems the airframe fared well during that flight. I haven't noticed anything twitchy in the flight trajectory. Let me know otherwise.

I would rather turn my eyes toward the startups way of functioning, generally prioritizing anything but spending that investors money, something that does exits in the Industry but stands exacerbated at the extreme here. IMOHO, they are just delaying and bypassing costly flight testing an airframe that would need, anyway, some modifications. It's so cheap to endlessly continue with design In aerospace.
 
Last edited:
Nicknick said:
I wonder what all those terabits are worth when flying around without even retracting the gear. Probably all the information was, it is by far too risky to fly it a second time...Very likely, the wet hands of the pilots was all they needed to know...

I'm not an aircraft expert, but I guess with some experiences in aircraft design (maybe by building model planes), the plane would have had less problems and could have even used the originally intended runway…

Thanks God, some external proffessionals are doing the ongoing redesign!
Click to expand...
Doesn't it feature a FBW system?
 
They had to go for a longer runway, which clearly showed, that the plane didn''t behave as expected. What kind of information can you learn about aerodynamic efficiency when flying with extended gear?

Someone here in this thread said, the FBW system was never installed.
 
A while back, an interior picture of the prototypes rear fuselage showed what looks like control cables I.e the type that are tugged on by the pilots. A quick search of the web and I can’t find it, indeed pictures of Alice’s prototype interior seem to be non existent.

As I said before they announced the move to the longer runway, a simple look a tailplane volume fractions suggested marginal pitch control moments.
 
True. But everything can fly with enough Speed. (Even high speed trains do hop.)
Do we see any tailplane exaggerated deflection during takeoff & landing? Longer runways is probably more in line with the mass at takeoff. Think rejected landing requirements and minimalized wheel hubs with that far forward projected front wheels (making more difficult to brake hard in that kind of events). I don't even know if the main wheels do not seat below the batteries when extended, making difficult or dangerous to break hard.
Multi-brake discs do generate a lot of heat in emergency situations.
 
Last edited:
A small highly loaded surface (in this case the elevator) will just stall if forced to too high an incidence. Hence the way to generate more aero load for a given incidence, is more airspeed. The ground effect is most likely also increasing which will be going in the wrong direction I.e requiring more nose lift moment. So now for take off velocity at rotation Vr, goes up and the kinetic energy increases by the square, which is bad news for stopping within the remaining runway (aka balanced field length). The brakes convert the kinetic energy into potential energy and the amount of energy they can accumulate before melting is governed by the thermal mass in the disc’s. That’s impossible to change if you’re original calculations are wrong but you can get a bit more stopping performance from a reverse propeller pitch (beta pitch, ok for flight test but a no no for certification) ….. as long as you don’t run out of runway.
 
Last edited:
Brake transforms kinetics energy into heat. Potential energy is what stands in your system to be used.
Here all the heat is wasted (I haven't heard about any regenerative brake heat exchanger... ).
 
@Zoo Tycoon : The break heat is not only adsobed, but also distributed to the surrounding air. Think about the enourmous amount of energy which is released by the breaks of a race car. The first disc brakes were used on planes, propably because of the better heat dissipation compared to drum brakes.
 
Nicknick said:
@Zoo Tycoon : The break heat is not only adsobed, but also distributed to the surrounding air. Think about the enourmous amount of energy which is released by the breaks of a race car. The first disc brakes were used on planes, propably because of the better heat dissipation compared to drum brakes.
Click to expand...

A high energy rejected take off is an event that takes about 20-25 sec. During this time heat is generated from friction from the discs being forced together. During this 20-25 sec there’s only an insignificant heat transfer from the discs to the air and the heat flux from the friction is immense (megawatts). The discs have to be able to absorb this heat without compromising their static strength or fading friction. After a max energy stop, cert regulations require a short taxi to clear the runway, and then a few minutes without causing a fire beyond the brake itself.

For a normal braked stop the brake will load up with heat due friction, over 15 or seconds, after which will then cool over the following 20-40 minutes. Brake cooling fans can be built into the wheels to speed thing up. The aircraft is forbidden from flying if the brake packs exceed a certain temperature as they might overheat (leading to fade or disc failure…. nasty) in the event of a rejected take off.
 
Take a look on the breaks of race cars, they start to glow almost immediately when they start to break and stop glowing in less than a second when the brake is released. The glowing colour also doesn’t really change after the first second.

However, I think we can both agree that brake performance is not a really critical part in this concept.
 
Given the mass of battery, yes it is. It means that, probably, no brake are available on the civilian market that fit that airframe size (generally, airframe would be roughly 50% lighter - this is why I was pointing at the wheel hub size ;)).
Probably that there is also no chance they plan to use mil specs, in regard of the extra costs.
 
I guess, breaking mainly with the props will not be an option for the FAA.

With the range getting shorter, overweight and the burn rate of the money, I believe they will do something very similar to Lilium, by using a fixed landing gear for the next generation.

The potential problems with a shift of the CG by different numbers ans seating postion of the passengers will not be avoided with minor changes. As mentioned here before, nearly all the variable load is in front of the center of lift...
 
thepointsguy.com

A Look Inside Eviation's All-Electric Alice Commuter Plane - The Points Guy

Eviation is hoping to receive FAA certification as soon as 2021, with the aircraft entering commercial service in 2022.
thepointsguy.com thepointsguy.com

I thought I would post some detailed images of the very first prototype that burned down before its first flight for comparison with the current aircraft being flight tested. Even though the company never admitted it, they must have had some serious CG issues caused by the weight of the batteries that forced them to select a tailwheel configuration, which was ultimately rejected by potential customers and completely discarded. So this project has had design difficulties since the very beginning. Very interesting to note that back in 2019, they were claiming a whopping 650 miles of range.
 
I believe, the tailwheel configuration was choosen to protect the rear propeller during rotation
 
Nicknick said:
I believe, the tailwheel configuration was choosen to protect the rear propeller during rotation
Click to expand...

But for a while it was rear prop engine with a nose landing gear, as you say hopeless.

And before that, it was a wingtiped engine twin, again utterly hopeless if you lost thrust from one side…. Say a blade came off like happen recently to Vertical’s XV4.
 
Nicknick said:
The prototype is a super complex design with pressurisation, fly by wire, retractable landing gear and a completely new propulsion system, not an easy job for the FAA.
Click to expand...
Nothing special about any of those items you mention, and no different to any clean sheet design (except that's it's electric of course).

It's Eviation's job to provide the evidence that demonstrates that the aircraft fully complies with all existing applicable Certification Specifications, not the FAAs!
 
Nicknick said:
What kind of information can you learn about aerodynamic efficiency when flying with extended gear?
Click to expand...
It's not uncommon for landing gear to be left down during a new design's first flight.

What IS very unusual is for a flight test campaign to consist of a single 8 minute flight, which is then declared (months later) to have provided everything they needed to know about the aircrafts performance....!
 
I know, that it is the way to do it for the first flight, but if you really want to learn about the behaviour of the plane and if it can fullfil the expectations, I assume you need to test it in the most used configuration with the gear up.

Fly by wire is still demanding and not standart. Of course, pressurisation is nothing new, as well as retractable landing gear, but both things add a lot of complexity and dont make a lot of sense for a (in reallity) short haul aircraft.
 
Zoo Tycoon said:
But for a while it was rear prop engine with a nose landing gear, as you say hopeless.

And before that, it was a wingtiped engine twin, again utterly hopeless if you lost thrust from one side…. Say a blade came off like happen recently to Vertical’s XV4.
Click to expand...
The wingtip version also had a rear propeller, I guess that was the reason why they wanted to have a wheel at the end
 
Not this one;-
 

Attachments

  • 3FEEAEB9-89E9-409F-A94E-6D23269BF70D.jpeg
    3FEEAEB9-89E9-409F-A94E-6D23269BF70D.jpeg
    804.8 KB · Views: 16
Video of wind tunnel testing of the modified Alice design is now up on Eviation.com!

Looks like the wing, fin AND tailplane area have all been significantly increased by lengthening chord...
 
Nicknick said:
Fly by wire is still demanding and not standart. Of course, pressurisation is nothing new, as well as retractable landing gear, but both things add a lot of complexity and dont make a lot of sense for a (in reallity) short haul aircraft.
Click to expand...
You are quite right, it would seem to be very ambitious to develop and certify fly by wire for a short range aircraft of this size, although you can understand the desire for weight saving over a traditional mechanical system.
 
Nicknick said:
I know, that it is the way to do it for the first flight, but if you really want to learn about the behaviour of the plane and if it can fullfil the expectations, I assume you need to test it in the most used configuration with the gear up.

Fly by wire is still demanding and not standart. Of course, pressurisation is nothing new, as well as retractable landing gear, but both things add a lot of complexity and dont make a lot of sense for a (in reallity) short haul aircraft.
Click to expand...

I agree that the current configuration doesn't make much sense for a 9 seat aircraft with less than 200nm range. They should have gone for a simpler design right from the start. In my opinion the Electra eSTOL will probaly have some success while this design won't even cross the finish line and enter service. It's simply too heavy for the battery tech available right now. The fact that they essentially grounded their prototype after racking up a whopping 8 minutes of flight time is a huge red flag for me, and the explanation that they were able to gather all the data that they needed from that one flight just doesn't pass the smell test.

www.flyingmag.com

Electra.aero Surpasses 2,000 Orders for Hybrid-Electric Aircraft - FLYING Magazine

The manufacturer estimates the orders will have a market value north of $8 billion once fully realized.
www.flyingmag.com www.flyingmag.com
 
A STOL concept is the most logic choise for an electric airplane. In most cases, VTOL is totally unecessary (e.g. with the inteded use of the Lilium Jet) and STOL really helps for a short range aircraft.
 

Similar threads

Back
Top Bottom