Why ever would one not want to put a weighty pod on the tip of a thin and apparently greatly flexible wing? And make it have a large gyroscopic component on top of that. Not sure which is the topper - the ever so racy choice of the V-tail or the tiny butt-prop.

I thought those design choices had been thoroughly exhausted in the 1930s Italian aircraft industry with echos going into that strange collection that Germans built for WWII.

In unrelated, but somehow similar news, Peter Sripol did a 30 foot span foam-board airplane with 50 electric motors and matching props across the wing leading edge, but lack of stiffness (and colliding with the launch vehicle) made flying itfor more than a few seconds to almost an entire half minute more interesting than it should be. https://www.youtube.com/watch?v=3aee2qDauTQ

Sigh. Alice 2018 was likely designed by someone who had never certified an aircraft. When they got around to the one engine out case the configuration was doomed.

How are wingtip-mounted motors better than the tail-mounted motors for an engine-out scenario?

"Why ever would one not want to put a weighty pod on the tip of a thin and apparently greatly flexible wing?" ... never seen an F104, or a Learjet 31 ?

yes, I know something to be done carefully, but there are reasonable reasons for doing this (and for being very careful about doing it).

I find it "funny" that the original design supposedly took advantage of wing tip vortices, and was a new creative solution to a problem. Only to revised itself to a much more traditional design. To be sure, if we don't try new things we won't learn.

One issue they may have had is the weight a cables from battery (or whatever) to motor.

why to the engine nacelles have large inlets (where they had none before) ?

another day in paradise, or is paradise one day closer ?

https://www.eviation.co/aircraft/#Alice

If we imagine that the fuselage aft of the wings is full of battery and power electronics then the CG change from empty to fully loaded looks pretty dramatic.

The horizontal stabilizer and elevator look small.

Quote (rb1957)

why to the engine nacelles have large inlets (where they had none before) ?

Because even electric motors need cooling.

A logical placement for the batteries is under the cabin floor. Mind you the "terrible" energy density of batteries means either you don't go far, or you have blister like an A380 under floor !?

Another option might be H2 fuel (instead of batteries) ... but that of course brings a Whole bunch of different problems with it.

and where'd the windows go ? DHL wouldn't be interested in pax, so now maybe a freighter ?

another day in paradise, or is paradise one day closer ?

The absence of windows is likely specific to DHL's application. Seems that this could be either a commuter or freight aircraft.

I expect DHL will get rid of the pretty tapered rear fuselage and go for a cylinder plus fairing...

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

The problem with doing anything with wing tip vortices is they are fundamental to the generation of lift - like inescapable. Anything clever one comes up with is just a patch that makes the flow look like it comes from a longer span - which is usually much cheaper to do unless, like large passenger/cargo jets the space at the airport is the thing limiting span.

Observe winglets - the greatest gift to stupid ground handling accidents ever. Watching one wing tip that would have passed over or under a wing or horizontal stabilizer instead slash its way to 10s of thousands in damage because the operator didn't want to pay a couple of ramp workers to keep an eye on clearance during pushback or taxi on the ramp tickles me in a way that only that famous truck-scalping bridge can approach.

So what are those inlets on the engines for?
Demonstration of an ignorance of blockage factor maybe, they look way too big for engine cooling, and its a terrible place for a heat exchanger.

I suppose the tapered fuse doesn't matter if they are hand loading parcels or if the hold is a constant section and gap between the tapered skin and the hold is filled with battery's (not a completely silly idea).
Look at the waste space in that fuselage
https://www.eviation.co/wp-content/themes/eviation...

The payload difference between freight and passenger seems small (100 lbs) a bit of gillliner, carpet tape and a couple of cargo nets doesn't add up to much compared to 8 seats and interiors (plus the ducting and electrical plus the other passenger related bits and pieces).

Apparently pitching to Fedex with windows on your plane pictures is a big no no, guess the same might apply to DHL.

Quote (3ddave)

Observe winglets - the greatest gift to stupid ground handling accidents ever

nah everyone just needs to put their pitots on their wing tips (la F27) then ground handling issues just leave neat round holes in everything.

Wingtip engines are NOT better for a one engine out condition.

"Wingtip engines are NOT better for a one engine out condition."

did anyone think they were ?

whilst worst position for engine out there "could" be other redeeming factors that off-set this and make it a reasonable design solution.

another day in paradise, or is paradise one day closer ?

Sorry, the renderings' quality made it look like the wingtip motors were the "new" design, and the OP didn't specify...

The new configuration looks a lot more conventional...which is not a derogatory term, people have looked at wing/tail/engine configurations for over a century now, and certain configurations just work better.

Though, a rotor strike on tail mounted fans might be an issue for takeoffs?

the new location looks better for "prop ground strike" than the previous ...

though maybe they'd've added a ventral fin (a la Do335) ...

(edit) ... oh, I notice the "tail dragger" config ... the "prop ground strike" not so much of an issue with the earlier design ... maybe why they went this way ?

another day in paradise, or is paradise one day closer ?

Same issue as the proposed Embraer regional airliner configuration in the other post... Is the cargo door next to the prop?

It seems that some have not followed the "Alice" from Eviation with quite the same point of view that I have, or not followed it at all. I don't blame you - it's always been a foolish paper-airplane right form the get-go and has yet to look like it has the potential to be a successful design. This post is perhaps another example of poking fun on the internet. If you see it that way, then no worries, ignore me. This is only meant for fun.

The 2018 model's tip-pod engines were hilarious. To see them actually built was amazing and raised the prospect of seeing video someday of a dramatic ground loop engine blow-up. Since that could have caused some fatalities, it was ironically fortunate for Eviation that instead they had a battery fire which destroyed their prototype.

The current concept is profoundly flawed, but less obviously so. The tail cone is sleek but extremely flexible, being so narrow. It once again demonstrates that the designers are artists, not bounded by engineering. There are other details that will be very difficult to master with the proportions they show, such as directional stability, one-engine out, landing speed, aeroelasticity of the wingtips and tail. Perhaps others I haven't yet noticed.

Striking any deal with DHL by showing them that concept is a new level of amazing.

I was just struck by the thought, if that is the best of their airframe design, what on earth does the electrical system architecture look like?

Yes, the few images I've seen look doubtful, but for GKN to be involved as a supplier of both major structural assy's and wiring harnesses, it does their reputation no favours if the project were to fail. For that reason I would hope that they have done their homework in assessing the project's viability and technical feasibility.

They seem to be getting somewhere, now.
The proportions still don't look right, but better than the original.



That's an airspeed probe on the nose. That's always seen on flight test aircraft. Expect a flashy announcement, soon.

A quick sketch and scale gives a total wing area of 320 square feet, hence a wing loading of 52 pounds per square foot when loaded at MTOW. That's pretty normal for a "bizjet" or "bizprop" style plane. Don't take that too seriously, though - I just traced the marketing sketch, FWIW.
Roskam notes that higher wing loading translates into a smoother ride for passengers.

With no chemical fuel being burned, then MTOW = MLW.
With no fuel, only controls inside the wing, its internal structure might be very simple.

I hope they put batteries in the wings ... replacing the inertia relief of the fuel.

great observation about MTOW = MLW ... this impacts conversion a/c significantly. Even worse, for conversions, is MTOW is limited MZFW (for wing fuel at least).

another day in paradise, or is paradise one day closer ?

RE the large inlets as seen in the front-view photos... there are no corresponding aft view photos showing cooling air exhaust. IN must= OUT.

I wonder if small turbines are being employed on this prototype... to be replaced or made optional... to electric motors?

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

typical engine intakes, there'll be an exhaust at the other end.

But that's "odd" .. aren't these electric engines ? or maybe they're doing a gas engine proof of concept. MagniX do some good work replacing gas engines with electric motors, so I guess space is similar ? oh, see MJ's reply (12th August) to this earlier question of mine. Ok, cooling air for electric engines, and similar exhaust (not shown).

another day in paradise, or is paradise one day closer ?

maybe name should be changed to "Lorina" ... Alice's older sister

another day in paradise, or is paradise one day closer ?

https://www.thedrive.com/the-war-zone/43838/spaces...

Engine and taxi tests.

Alice "specs" ... check the asterisk against the range ... "no payload".

I admit, a funky, interesting fuselage cross-section. I assume unpressurised.

another day in paradise, or is paradise one day closer ?

• https://files.engineering.com/getfile.aspx?folder=5e360da2-9615-4f44-836f-b

I'll chime in on the motor inlets... provided those are still electric motors in there:

I'll try not to say anything proprietary here but we're talking my game...I've been asked to bid on a few electric powerplants cooling systems. Electric motors get hot. Cooling them with other large current draw items seems to be where all the brainstorm projects started a few years ago, but it doesn't seem to make sense come production prototype designs.

There's a reason almost all aircraft powerplants have been and will probably continue to be air cooled. The air-cooled FW190 was considered "clean" compared to the liquid cooled ME109.

Ultimately all aircraft are air cooled - the advantage of a liquid intermediary is that it allows a more compact power plant to depend on a larger/more effective heat transfer system that can be placed elsewhere.

Recall too that liquid cooling allowed the P-51 to use a radiator system to generate extra thrust, or so I understand. Apparently this was also used in the ME-109, which wasn't as effective due to less optimal flow control. It seems a waste to chuck heat out the back without taking advantage of it.

aka the Meredith effect. https://reports.aerade.cranfield.ac.uk/bitstream/h...

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

I wonder how much cooling they get on the ground ? without much airflow ??

but then maybe that's why they're so big ... at altitude it is less of an issue.

another day in paradise, or is paradise one day closer ?

Electric motors need not idle.

I guess the critical cooling case is max altitude since the power out is independent of altitude unlike typical piston engines.

There is an interesting ARC report R&M 2498 "The Aerodynamics of the cooling of aircraft Reciprocating Engines" which summaries the UK's WWII experience (never found a digital copy online). One of my take aways from the report is that efficient cooling tends to require lots of space or get premium aerodynamic real estate. Liquid cooling may allow one to move that space to somewhere "cheaper".

in the Liquid verse air cooling discussion, the above report gives some interesting numbers
@100 ft/sec
11.5 lb drag for the air cooled Hawker Tempest II
13.0 lb drag for the Nose radiator for the Hawker Tempest I
11.0 lb drag for the Wing leading edge for the hawker Tempest I
Noting that the airframes just differ in the use of an aircooled engine (Tempest II) or liquid cooled engine (Tempest II).

Do the electric motors require to be warmed up before takeoff?

For an electric airframe with pressurization, are we likely to see engine cooling with venerable geometry inlets / outlets?

Electric motors ordinarily don't care much about their operating temperature, although they do require some cooling in operation. Lithium batteries do care about their operating temperature, best range seems to be 10 - 60 C, and in automotive applications, they require some cooling during operation and definitely during fast-charging. The motor inverter also requires cooling during operation. The cooling loads in terms of kW cooling relative to kW of mechanical power output are nowhere near those of a combustion engine, but also the temperature difference to the surroundings is also nowhere near those of a combustion engine ... it is entirely possible that the volume of cooling air required, and the size of a radiator required, is going to be same-ballpark. Smaller but not drastically so, is automotive practice.

Cabin HVAC and pressurisation is a different situation from turbine-powered aircraft. It's going to need active compression of outside air.

Outside air temp at high altitude is going to be way lower than the temperature the batteries want. It may turn out that during operation, waste heat from the motor and inverter supplies heat to the battery and that loses it to the outside air. Doesn't help with excess battery heat during fast-charging on the ground, though. That will still need active cooling.

that was along my line of thought. ground cooling could be a ground cart.

another day in paradise, or is paradise one day closer ?

I wonder how you ensure the remaining range ? the required reserves ??

sure, not awfully different to fuel but different none the less.

I find "range with zero payload" an interesting point. Payload of these electric planes is a small fraction of total weight (in this case 2500 lbs in a 16500 lbs plane). Does max payload reduce the range by 1/8th ?

another day in paradise, or is paradise one day closer ?

"I wonder how you ensure the remaining range ? the required reserves ??"

Especially with a 5 year old battery, if my phone is any indicator of the problem.

Dedicated reserve power supply.

Would you not come up against the lithium equivalent of peukert's law?

For instance, I can buy relatively cheap batteries that have maximum discharge current of 1C. If I want to discharge at 6C I pay more for my battery, or fit a bigger battery.

By all means reserve power in the main battery, but a separate small battery is tricky. OTOH, I suppose a reserve battery won't be being used for take-off/climb.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

State of charge prediction has generally been pretty poor. Simple enough to check the voltage, but I've seen batteries that have a no-load voltage that vanishes under a tiny load. Testing under full load only indicates that for that amount of time the battery was able to keep up, but the test is destructive in that the charge that was there is no longer there.

The advantage to fueled aircraft is that generally fuel is burned at a constant rate regardless of the amount of fuel available; the energy per pound of fuel doesn't change if the tank is completely full or nearly empty, whereas in extracting energy from a battery the state-of-charge has a serious affect, both by being difficult to measure and as it is depleted the chemistry adds to the electrical resistance, further decreasing the rate at which energy is extracted. In aircraft that extraction is nearly constant for the cruise portion of the flight which includes running a race-track or diverting. To the advantage of fuel - that reserve is available when the plane is lighter, having lost weight due to fuel burn while batteries are literally becoming dead weight over that same period.

Regulation wise, I don't see that there will be a good method to deal with it. It will have to come from decades of flying and data gathering and all the time the chemistry and construction of batteries will be changing, generally rendering the previous data useless for further predictions. Offsetting that will no doubt be increased fidelity in electrochemistry simulation - similar to how thermal analysis is done now for complex shapes. It will look at ion transport in the battery and the effects of that and temperature and barriers due to already reacted material. There are probably initial studies now and more planned for even larger supercomputers to gnaw through.

Software is going to monitor current input and output from charge storage systems largely based on service history. The software itself will be certified... the actual hardware is disposable. It will determine range, while monitoring available alternates realtime. Basically the aircraft ETOPS self certifies continuously. EOPS.

"certifies" ? surely the range calculation (s/ware) is certified. Possibly the s/ware continuously updates ? I'd still be worried by the amount of charge I can extract from the battery ... even if they run 100s of scenarios.

another day in paradise, or is paradise one day closer ?

'Alice' Update...

Eviation readies for Alice maiden sortie as ground tests wrap up

Eviation is gearing up for the first flight of its all-electric Alice prototype in the coming months having completed ground testing earlier in May.
However, the clean-sheet aircraft developer is staying tight-lipped on precisely when the proof-of-concept Alice prototype will take to the skies, simply saying the milestone will occur “this summer”.
... ...
https://www.flightglobal.com/ebace-2022/eviation-r...

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

Eviation’s Alice completes high-speed taxi test, ‘final’ step before flight
https://www.flightglobal.com/airframers/eviations-...

Is the new ALICE FINALLY ready for flight???

Regards, Wil Taylor
o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

Yes, they did it:

Eviation’s all-electric Alice aircraft makes maiden flight

https://www.youtube.com/watch?v=qjPO4_oe5h8

Long article in yesterday's Seattle Times. They apparently have no intention of getting FAA cert. for this aircraft. The (new) CEO says they need better batteries, which apparently are several years away, to make a viable passenger carrying version...

https://www.seattletimes.com/business/boeing-aeros...

Better batteries? They need better batteries? This is my shocked face.

Noble mission statement.
New/unique configuration airframe.
Composite materials.
All digital flight controls/systems.
Electrical propulsion by 100% battery power.
Extended [possibly indefinite] experimental-development/test/design/build time.

I can't shake off the feeling this looks-like 'death by a thousand cuts'.

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

so whilst Eviation says "just kidding about certifying these things", then there's this in Flight ...

"French start-up Aura Aero has disclosed 130 tentative agreements for its hybrid 19-seat Electric Regional Aircraft (ERA)."

I think Business aviation is where this market should start. Current batteries can give you reasonable range, just low payload and low cycle count (if you have to recharge batteries in situ).

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

Elsewhere it is mentioned there is a Seattle electric float plane that has been flying for some time.

https://harbourair.com/harbour-air-magnix-and-h55-...

yes, a beaver (DHC2) ... maybe restricted or experimental category ?

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

in Dec '19 ...
"magniX and Harbour Air will now begin the certification and approval process for the propulsion system and the retrofitting of aircraft. Once the certification is complete, the rest of the fleet can be magnified with magniX’s all-electric propulsion technology."

since then, cricket noises ?
correction, in August '22 ...
"The Harbour Air ePlane team is excited to announce that the first direct all-electric point to point test flight has been completed. The historic De Havilland Beaver has been completely retrofitted in 2019 to operate using 100% electricity flew 45 miles in 24 minutes. The aircraft left their terminal on the Fraser River adjacent to YVR and landed in Pat Bay adjacent to YYJ. This is a major milestone in the advancement of all-electric commercial flights."

so not certified yet ? I wonder what the TC STC database has to say ?
still 45 miles is pretty good ... covering a narrow water channel.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

Quote (3DDave)

Elsewhere it is mentioned there is a Seattle electric float plane that has been flying for some time.

Harbour Air is based in Victoria, BC. The article meant that it can travel from Victoria to Seattle, not that HA is based there.

Quote (rb1957)

since then, cricket noises ?

Gee RB, have you not been involved in a STC project that went on for more than 4 years before?

This also shouldn't come as a surprise, but the FAA and Transport Canada still have their knickers all in knots about lithium batteries. They have had various groups inside and outside their ranks arguing for a decade on how to deal with this technology. There is still no consensus and no sign of a resolution either.

I don't see a great solution for batteries - they are basically mixing fuel and oxidizer in one container. If there's a glitch there is only thermal inertia and speed of reaction that slows it from exploding, though when confined they can rupture explosively. The ideal battery should have the same performance as a bomb - able to release all the energy instantly.

They need to build a more ideal battery which becomes closer to being a bomb.

No no, scientists are working toward a battery that can be charged faster and to release its charge at a higher rate.
Oh, wait... hmmm...

"though when confined they can rupture explosively." ... last time I checked gas tanks could do the same thing.

yes, we're developing a new technology which will be painful.

A fundamental decision is where to put the batteries. Yes, I know a million decisions to trade-off; but this is IMO a primary reason why retrofitting is "doomed" ... without batteries in the wings you're limited to MZFW as MTOW (unless you're smart enough to use a DHC6 ... fuel in the fuselage). Batteries in the wing will be an utter pain to design, batteries in the fuselage are much easier, and allow for "quick change" paks (rather than charging in situ) to improve turn-around.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

Quote:

"though when confined they can rupture explosively." ... last time I checked gas tanks could do the same thing.

I wouldn't say "the same thing". Excepting things like solid fuel rockets, typical fuel tanks for combustion engines do not have the oxidizer inside (as was well pointed out by 3DDave). So, Hollywood special effects aside, fuel (without oxidizer) tanks do not explode like a bomb. In fact, the tank designers typically take care to have a fuel tank that is subjected to crash and fire situations, vent or rupture in a controlled manner so as to limit the rate of chemical energy release to the outside environment.

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

These electric aircraft programs are facing lots of engineering challenges. Especially with the battery integration. I wish all the success to the companies that are pushing the envelope so we can have cleaner skies. Batteries can experience thermal runaway, releasing hot gasses and fire, releasing high temperatures inside and outside the airframe, so especial consideration needs to be considered, due to thermal expansion for dissimilar materials (thermal stresses), material strength at high temperatures. Specific provisions are required to release the heat and fire in a safe fashion. I witnessed a thermal runaway test at an EVTOL manufacturer facility, it was a scary thing to watch.

I wonder where the batteries are installed in the Alice aircraft. Wings look very thin profile, and the cabin is extended, probably in the AFT fuselage. wonder how many batteries is Alice carrying to complete its mission.

Macm,
Answer to your question was in the Seattle Times article, linked by Btrueblood on 30 Sept, above.

from Seattle Times article (yeah, I know you need the Coles notes ... TLDR ...

"It’s powered by just over 21,500 small Tesla-style battery cells that, at just over 4 tons, make up fully half the weight of the carbon composite airframe.
...
“Are the batteries on the prototype aircraft capable of propelling the certification aircraft, capable of providing sufficient energy? The answer is no, absolutely not,” Davis said.

but tellingly ...
"In an interview in February, Davis had spoken of pushing hard to certify a production model of the airplane for passenger service in 2024." But 6 months later ..."On Monday, he said that goal is probably five years away."

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

and today in Flight ...

"German start-up carrier Evia Aero believes it is launching into the market with a fleet of zero-emission aircraft at the optimum time, as it looks towards the start of operations in 2026." In the background is a picture of Alice. It sounds like Evia Aero is to operate Eviation's Alice ... but that could be "hype and suspicion". I don't see an electric powered plane certified by '26, even a retro-fit (like a King Air). But maybe it's "optionally electric" or hybrid or ...

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

and today in Flight ...
"Mexican start up Aerus intends to acquire 30 Eviation Alice electric aircraft"

compare with 30th Sept post ...
"In an interview in Moses Lake on the eve of first flight, Eviation CEO Greg Davis conceded that the prototype that took off Tuesday is not the design the company will build later.
He said Eviation needs still-to-be-developed advances in battery technology to make its planes commercially viable.
'Are the batteries on the prototype aircraft capable of propelling the certification aircraft, capable of providing sufficient energy? The answer is no, absolutely not,' Davis said."

"In an interview in February, Davis had spoken of pushing hard to certify a production model of the airplane for passenger service in 2024. On Monday, he said that goal is probably five years away."

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

Kerosene would never be approved today...never mind AVGAS.

Battery technology has the "just over the horizon" problem.

But companies like True Blue Power have the advanced battery tech. Understanding that battery, it's first & foremost a state machine. If and when suitable battery tech is available they'll be able to protect it.



Here their Li-Ion battery is shot with a .50 Cal bullet:

Link

and today in Flight ...
"Japanese group secures delivery slots for Vertical Aerospace VX4
19 Jan 2023

Marubeni plans to launch eVTOL flights in time for 2025 Osaka World Expo and has carried out proof-of-concept trials using helicopters. "

Someone's going to be disappointed !

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.