New Alice Starts Taxi Testing

Homebuilt Aircraft & Kit Plane Forum

Help Support Homebuilt Aircraft & Kit Plane Forum:

SpruceForest

Well-Known Member
Joined
May 23, 2022
Messages
236
So to temper expectations, 2037 is about as early as we can expect the next battery technology to support mass use, assuming we have a production prototype within the next 3-5 years... and that is without strategic material concerns (take a look at where your copper, nickel, and rare earths come from, and look at how the current denial of an improved permitting process in Congress negates any hope of near-term domestic or NA replacement), labor shortages, and other competition for scarce capital and materials playing into the estimate. Yes - if we did a Battery Manhattan Project, we could cut a year or two off that estimate, in recognition that the usual inelasticity of schedule where funding is constrained may be compressed a bit with lots of OPM (other people's money...aka taxpayer funds). If you want to look at the pacing piece, two factors dominate: status of the tech (production prototype status means 8-10 years to build out the manufacturing chains, get folks to adopt, etc.; anything less mature means added time, denoted as t sub unknown) and inputs (water/teen angst battery chemistry = simple, plentiful inputs; unobtanium/infeasium battery chemistry = difficult-to-source/impossible to scale inputs).

Building battery-powered airplanes is not the problem, or at least battery powered airplanes absent the whole battery tech piece. Coming up with business models that a) don't generate more carbon and related 'pollutants' than what is being replaced, and b) competitive with current models is THE enterprise side of the problem. Solve the battery tech issue and the business model issue MAY be addressed, but a sure sign of a failed tech solution with coupled business model is when the only way to make those ugly facts more attractive to investors, customers, and potential users is to legislate or ESG your way into being less ugly than your fully built-out, fully tech-leveraged, successful competition.
 

Dan Thomas

Well-Known Member
Joined
Sep 17, 2008
Messages
7,495
Yes, when that photo first appeared I posted in several places "This is what happens when you let graphic designers configure airplanes." To my eye, the biggest problem here is that the MAC location clearly makes it statically unstable unless the batteries are all located right in the nose.
Exactly. Pretty stark, isn't it?
 

Tiger Tim

Well-Known Member
Joined
Apr 26, 2013
Messages
5,061
Location
Thunder Bay
I met an investor in an electric airplane startup; when asked why he invested. His answer was pretty simple. He has a certain amount of capital set aside to chase moon shots. And he picks the best moon shot he can find; not expecting a return but hoping for one, and hoping to leave society in a better place.

Kinda interesting take....

Tim
I bought a lottery ticket at a gas station the other day. Same idea, I guess.

-A different Tim
 

Monty

Well-Known Member
Joined
Jul 15, 2010
Messages
1,367
Location
Fayetteville, AR / USA
Breguet Range Equation does not care how the aircraft is powered. Apparently none of the electric aviation enthusiasts know about this. Batteries in the conventional sense will never be as efficient as fuel and air for aircraft. No way around this. basic physics. Makes it hard for me to take them seriously. You will also have to design the aircraft structure to land at gross wt. Another hit. The higher the energy density of a battery, the closer it is to an explosive....just chemistry. Unless the batteries are removable modules- mission planning trading fuel for payload is impossible. So is any kind of quick turn. The only place to put batteries that make any structural sense is in the wings...so I guess the wings must be removable.

I'm sick of willful denial of basic physics. Hopium is the enemy. Someone prove me wrong (you can't)
 
Last edited:

addaon

Well-Known Member
Supporting Member
Joined
Feb 24, 2008
Messages
2,305
Location
Kanab, UT
Battery energy density is currently lower than energy density of common fuels, excluding oxidizer weights. By quite a large margin, but that margin will only decrease. Landing at takeoff weight is a disadvantage, but not an infinite one -- other advantages can easily outweigh it. (Heck, I've seen some suggestions to use aluminum air batteries, which have 10x the energy density of lithium secondary batteries... but would land at higher than takeoff weight. I've only seen those discussed for aircraft that complete their mission rather than land, though.)

Not sure why quick turn would be hard. It takes less time to charge a battery than to fill a fuel tank, if that's what you design for. I've worked with 60 kWh-class batteries that charge in 20 minutes.
 

Monty

Well-Known Member
Joined
Jul 15, 2010
Messages
1,367
Location
Fayetteville, AR / USA
I'll also say this about the original design of this aircraft. It's much more insidious than a graphic designer...The design was obviously driven by a theoretical absolutist academic. Someone I have no time for. The tell tale signs are the following: The wing tip engines are there to counteract the loss from tip vortices. Because they believed induced drag is a significant thing (again don't understand Bruguet) The engine in the back was to eliminate momentum drag from the boundary layer. This actually has some merit. It has to do with how the equations for drag and propulsion were derived, but I digress. The rest of the configuration is pure academic BS. The designer has never flown or operated an aircraft. Probably an aero "expert" with no thermodynamic or structural/practical knowledge...empowered by investors with even less knowledge. If I could short the stock I would with leverage. 10 years return on investment in an inflationary environment...good luck.
 
Last edited:

Monty

Well-Known Member
Joined
Jul 15, 2010
Messages
1,367
Location
Fayetteville, AR / USA
Not sure why quick turn would be hard. It takes less time to charge a battery than to fill a fuel tank, if that's what you design for. I've worked with 60 kWh-class batteries that charge in 20 minutes.
I'm not sure exactly what you are talking about here. I work with batteries and fuel.
 

addaon

Well-Known Member
Supporting Member
Joined
Feb 24, 2008
Messages
2,305
Location
Kanab, UT
Hm, we might be talking at cross-purposes.

For turn-around on a passenger airplane, there are a bunch of factors, including getting the pax off, cleaning, boarding again, etc.; but none of those seem like they would vary significantly with propulsion type.

So the remaining part of turn-around would be refueling / refilling. For a turboprop, you power off, call the truck, hook up the fuel hose, and transfer fuel... I know the 737s run around 300 gpm fuel rate, but I suspect the Part 23 sized turboprops fuel at much lower rates. For a battery electric system, you power off, either run out a cable (which restricts locations, which is a big deal) or a truck (which has its own challenges), plug in, and wait for energy to transfer. This is most often limited by thermal limits on the battery. For current-day batteries optimized for power density, charging in 15 - 30 minutes is feasible. This may be ten minutes longer than fuel transfer time; it also may not be. It's certainly unlikely to be what determines if a route is feasible or not.
 

dave wolfe

Well-Known Member
Supporting Member
Joined
Dec 7, 2019
Messages
166
How many others here are experienced aircraft engineers and would have dismissed any notion of working on the project simply based on that original configuration?
Also, I have a hunch most people funding or working on the project agree with the petroleum fuel reduction schemes, or at least bilking taxpayers out of grant money intended for such. Im a bit too honest to go down that path.
 

addaon

Well-Known Member
Supporting Member
Joined
Feb 24, 2008
Messages
2,305
Location
Kanab, UT
Do you really think you can charge batteries faster than fill a fuel tank practically??? really?

Yes. I've worked on aircraft that charge about as quickly and conveniently as filling my Lycoming-powered aircraft. I don't see why this, of all things, is surprising.

Edit: Part of this is an indictment of how we fill GA planes today. Heavy hoses, dual connectors for grounding and filling instead of integrating them, variable flow rates where at least on my plane full flow means gas splashing off the bottom of the tank into my face and low flow means taking 5+ minutes per side... "roughly competitive with the current state of the art" isn't that hard to reach. I know the big guys get to do bottom-fill with single mating connectors, but we're talking about Part 23 at this point.
 

Monty

Well-Known Member
Joined
Jul 15, 2010
Messages
1,367
Location
Fayetteville, AR / USA
Oh, and ask any of them about reserves.....energy density that is orders of magnitude worse really impacts this requirement. If you have an hr of endurace...a 30 min reserve is debilitating. For hydrocarbon fuels...no big deal.
 

Monty

Well-Known Member
Joined
Jul 15, 2010
Messages
1,367
Location
Fayetteville, AR / USA
Yes. I've worked on aircraft that charge about as quickly and conveniently as filling my Lycoming-powered aircraft. I don't see why this, of all things, is surprising.

Edit: Part of this is an indictment of how we fill GA planes today. Heavy hoses, dual connectors for grounding and filling instead of integrating them, variable flow rates where at least on my plane full flow means gas splashing off the bottom of the tank into my face and low flow means taking 5+ minutes per side... "roughly competitive with the current state of the art" isn't that hard to reach. I know the big guys get to do bottom-fill with single mating connectors, but we're talking about Part 23 at this point.
Sigh.
 

addaon

Well-Known Member
Supporting Member
Joined
Feb 24, 2008
Messages
2,305
Location
Kanab, UT
Smaller than the average supercharger station. Less than a refinery. Infrastructure development is definitely one of the more fun projects related to electrification.
 

Dan Thomas

Well-Known Member
Joined
Sep 17, 2008
Messages
7,495
The higher the energy density of a battery, the closer it is to an explosive....just chemistry.
Some proponents point out the huge energy contained in a gallon of gasoline as a "whatabout" defense of their pet ideologies. But as you point out, batteries are, so far, a lot more unstable than gasoline, which is safe enough unless you crash, and Li-Ion batteries in a crash are also going to present problems.

Gasoline in a tank is safe. The airspace above the fuel is too rich to burn. Inside the typical GA airplane fuel tank is a wirewound rheostat, moved by a float, that controls a current to the fuel gauge to indicate fuel level. That rheostat is called a sender, and that sender is in the top of the tank, it has an open frame, not sealed, is surrounded by fuel vapors. That sender, when it gets worn, makes sparks. In the fuel tank. In that fuel vapor. And it doesn't explode. That's how safe it is. Take the cap off, though, and let those vapors out into the ambient air, and you have a flammable mixture.

I wish those batteries were as fire-resistant. How many gasoline-powered airplanes have had fuel tank fires in flight?
 
Last edited:

Dan Thomas

Well-Known Member
Joined
Sep 17, 2008
Messages
7,495
Looks like Alice needs about 20 batteries?
That's 1.2 megawatt electric substation. How much does that cost?
1.2 mW, at 500 volts (if that's the delivery voltage) gives me 2400 amps. The cable to carry that would be as thick as my wrist, I think. Bigger than any GA fuel hose. And by my possibly faulty calculations, 1.2 mW, at $.15 per kWh, would cost $60 for a 20-minute charge. That is an awful lot of electricity.

I don't believe the 20-minute recharge cycle. If that was possible, wouldn't electric cars be using those batteries by now? Lots of rich folks would gladly pay for that savings in time.

So what airplane has a 20-minute recharge cycle? And how many minutes of flight does that give it?
 
Top