Electric powered BH ultralight

[schu]

15hp is plenty of power to rock a bike around, even 5hp would probably be enough to cruise, and you can recover some of it every time you stop.

With an airplane, 15hp is absolutely nothing, and there is nothing to recover when stopping, not to mention the lack of electrical infrastructure at various airports to charge it.

All that said, it can be done, sonex did it, it just didn’t compare to a fuel powered airplane when it came to actually flying somewhere.

[Bdflies]

[QUOTE=schu;n47969]I honestly don't think this is going to work based on how much electric cars weigh and the cost. Here are a few things to factor:


I'm surprised. Looking at Schu's avatar, I judged him to be a young man. Based on today’s technology, I’d say the arguments are correct. However, when I began subscribing to automotive magazines ( in the 70’s), the unattainable 'holy grail' was 1 hp per cubic inch displacement. Years later, the goal was 1G lateral cornering. Recently I read about Ford's new "track day" GT that was capable of 2G lateral! Horsepower/ cubic inch? Who knows!
I'm an old dinosaur. But I absolutely envision the day when battery technology approaches the energy density of an equivalent mass of gasoline in a tank. Maybe I'm dreaming. But I sure wouldn’t bet against it! Aerodynamics have been refined for over a hundred years, so that part is fairly settled for our purposes. The concept of electric propulsion is in it’s infancy. I honestly think Bob is a pretty sharp guy, to start designing a useful, back country type airplane, in anticipation of developments to come.
C'mon Schu! Push that box a bit!

Bill

[Bcone1381]

I think about where we were 10 years ago, and where we are today, and use that trend to predict the future. An electric motor/battery pack does not have to be lighter than an equivalent piston engine, it just has to light enough.

Regarding cost, the largest cost in operating an airplane may be fuel, maybe the second is reserve for engine overhaul, third may be maintaining the engine. Eliminate those three will leave a lot of money to spend on batteries.

[jaredyates]

I've been watching Brian Carpenter's electric motorglider project. It is stalled at the moment due to company logistics rather than technological logistics, but interestingly he does talk about the possibility of using the battery power to climb to a soarable slope, then using a windmilling prop to regenerate when in the slope lift. I also fly paramotors and paragliders, and am watching the space closely for electric power as a means to self-launch into naturally occurring lift like thermals. When we stop trying to match electric power and IC in the same boxing ring, and let each one do what it does well, there are some off-the-shelf "today" options that are viable.

If/when Brian gets back on track with his project I'm a real customer prospect. Don't tell my wife, she might not know about that yet.

[svyolo]

I have been using rechargeable batteries since the mid 70's. NICAD, NiMH, and LI. Better batteries are always only a few years away. 45 years later, it is just a few more. LOL

The only big "improvement" in the last 5 years is cost. They have come way down in cost. The only big thing on the horizon for weight is what they call solid state batteries. The solid part being a solid instead of liquid electrolyte. A couple of car companies (including Toyota) just invested a bunch of money into a couple of companies that are developing them. That was a big change in course for Toyota as they have been convinced H fuel cells were the future.

The energy density is supposed to be double that of the best LI tech today. That means batteries that weigh half. They are "hoping" for useable batteries, for sale, by 2025.

Motor and controller tech have been good enough for quite a while. But the motors aren't cheap either. Lots of expensive metal.

I plan on watching and waiting while burning dead dinosaurs for as long as it takes.

[schu]

Schu is a young man, and also an engineer, and also one that has converted a lot of gas aircraft to electric, but only up to 25% scale. I have a 5kw helicopter, I have a 3kw aerobatic airplane, I understand the difference, and I'm using some of the best battery tech available today.

At the end of the day, the best battery tech stores maybe 300 watt/hrs per kilogram. Compare that to gasoline at 12500 watt/hrs per kilgram and you can see that we have a way to go, even if gas engines aren't all that efficient. Remember, a telsa model 3 long range only has a 325 mile range (translation, only about 280 ) and weighs 3800lbs. Compare that to a ford focus that weighs 3000lbs, and can do the same with 48lbs of gas on board.

That said, if you just need it to get you into the air (motorglider) then that could work, and you could cut some weight out with lighter engine mount and such...

[JimParker256]

Schu, I bow to your expertise in the field. But considering that the VAST majority of LSA use the 100 HP Rotax, which costs a LOT more than $16K, I think there could be room for even a "small" batttery breakthrough to make a game-changing difference -- specifically for those FBOs who are doing high-volume student flights. And they probably won't be using solar power, but instead using 220V (or even 440V) power from the local electric company. It's not free, but cheaper than gas. The big issue, of course, is figuring out a way to package the batteries so that a mere mortal can swap them out. Maybe 3 x 50-lb "suitcases" or 4 x 40-lb units. Lots of stuff to still work out, as you said, and even more $$$ to justify it all and make it work.

I've got a buddy who was working with Carol and Brian Carpenter at Rainbow to help engineer their power supply and charge management stuff. They kind of stalled out waiting for technology to catch up. Turns out it's a lot harder to build a real live man-carrying airplane than an RC model of same... But you already knew that!

[schu]

Jim,

The 80HP 912 ul is much cheaper than the 914.

https://www.leadingedgeairfoils.com/rotax-engines-parts/new-rotax-engines/rotax-912ul-engine.html

https://www.cps-parts.com/catalog/rtxpages/912rotaxengine80.php

http://zenair.weebly.com/rotax.html

https://www.rotechmotor.ca/PRICES.html

Given that is the engine that runs the electric pipistrel, that it's around 15hp stronger than the electric version, and can go for an hour on 24lbs of fuel, I just don't see how the battery tech is there.... If it was... I would be one of the first to build an electric airplane. I'm thinking about building an electric car some day. I think a Factory 5 818 would be a perfect place to start.

[schu]

Looks like someone beat me too it

https://www.youtube.com/watch?v=C3ppNzZZHDU

[bcbearhawkLSA]

I rest my case...

https://youtu.be/i9mCxhETCwM

[schu]

Pretty weak case if you ask me. From the specs:

payload fully equipped LSA 396 lbs. (180 kg)
standard endurance, traffic patterns 60 min + reserve
standard range at cruise 80 kts 70 NM (130 km)
nominal battery capacity 21 kWh
engine 50 + kW @ 2100-2400 rpm

In my example I suggested a 15kw motor at 45minutes needs a 12.3kwh battery assuming 90% efficient and 10% reserve capacity to not harm the batteries. In their specs you have a 50kw engine using a 21kwh battery. Now that's pretty easy math, at full power, with 100% efficient (it's not), and 0% reserve (you would destroy the batteries on the first flight) that's still only 25 minutes of battery.

This is why the standard range at cruise isn't even an hour (and I bet it's below 50% power), and the 60 minute numbers in the traffic pattern are almost certainly very careful recharging on descent, and very polite throttle inputs.

This airplane basically validates my numbers and I didn't even know about it. If you consider my numbers are for ultralight scale, and you double the motor and the battery then we have something pretty close to this pipistrel.

So if flying around for 45 minutes at a time, with a 396lb useful, with little ability to recharge at the destination airport, while telling yourself it's free when you have $100k of solar cells and electrical system mounted on your hangar, while touting that you are saving the planet does it for you, well, okay, I guess....

[svyolo]

And the batteries will start losing battery capacity after less than 1000 hours, probably requiring replacement before 2000 hours. The retail price for battery replacement would probably currently be greater than the cost of rebuilding a Rotax or O-235.

But you could apply for carbon credits and let "someone else" subsidize your toy.

[svyolo]

I believe there is also a little rule written somewhere requiring powered aircraft to land at their destination or alternate with no less than 45 minutes of fuel remaining. Electric powered aircraft are going to be exempt from this?

So the current Pipistrel takes off at the beginning of the flight, at critical fuel. If they flew just 30 minutes, they probably wouldn't have the juice left to climb to 1500', and cruise 10 miles. They may not be able to climb to 1500'. The Feds are going to grant an exemption for this, to give the FAA green points?

[zkelley2]

30 mins VFR. 45 IFR.

[JimParker256]

I believe there is also a little rule written somewhere requiring powered aircraft to land at their destination or alternate with no less than 45 minutes of fuel remaining. Electric powered aircraft are going to be exempt from this?

So the current Pipistrel takes off at the beginning of the flight, at critical fuel. If they flew just 30 minutes, they probably wouldn't have the juice left to climb to 1500', and cruise 10 miles. They may not be able to climb to 1500'. The Feds are going to grant an exemption for this, to give the FAA green points?

The FAA gave all sorts of exemptions (weight, etc.) to the rules for both ICON A5 and the Terrafugia Transition... But as for me - I'm sticking to Lycoming (or at least Lycloning) engines...

[svyolo]

I think I read that if you cut the current cost of batteries in half, you could get a cost competitive electric car. I would extrapolate that to "if you could cut the cost AND weight in half, you might get a useable primary trainer with 2 hours endurance."

That still isn't a useable airplane for most applications other than flight training, or something else that only requires 60 minutes of useable power, plus reserve.

It is still fun to watch what goes on, but I won't be spending my own money on it anytime soon, and probably not in my lifetime.

[rodsmith]

I agree with the opinions expressed about the current state of electric airplanes. As a sailplane pilot I think the perfect application of the current motor/battery technology is electric self launching sailplanes. The FES (Front Electric Sustainer) system uses a 22KW motor. System with batteries weights 110 pounds. Front mounted propeller with blades that fold back against the fuselage when not in use. The drag from the folded blades only costs about 1/2 L/D point. So a sailplane with a 40/1 glide ratio, would still have a 39.5/1 glide ratio with the FES system. Currently is a sustainer for 15/18 meter sailplanes. Two manufactures make 13.5M sailplanes that are self launching. Can take off, climb 1000M and have some reserve left on a full charge. They are working on a somewhat more powerful system to self-launch 15/18 meter sailplanes. There are some current sailplanes that can be retrofited with the system. We have a sometime glider operation on our airport but the towplane operator charges what I consider an exorbitant rate and is normally only available on weekends. I have found a few other sailplane pilots that would be interested in purchasing a used sailplane capable of being converted to self-launching with this system. Just thinking about it at this point.

[zkelley2]

Schu is a young man, and also an engineer, and also one that has converted a lot of gas aircraft to electric, but only up to 25% scale. I have a 5kw helicopter, I have a 3kw aerobatic airplane, I understand the difference, and I'm using some of the best battery tech available today.

At the end of the day, the best battery tech stores maybe 300 watt/hrs per kilogram. Compare that to gasoline at 12500 watt/hrs per kilgram and you can see that we have a way to go, even if gas engines aren't all that efficient.

A ways to go, but not quite as bad as it may seem. Gas engines are 30% efficient if they are lucky. Electric motors are generally at least 85% efficient.

That effectively makes the comparison 255Wh/kg to 3740Wh/kg. So a 15x increase in battery energy density would do it.

My favorite is the Metal-air cells.

[way_up_north]

I rest my case...

https://youtu.be/i9mCxhETCwM

A few things to respond to here....

Electric is the way of the future...just maybe not the near future..

.....tesla just bought a battery company that specializes in capacitors...a battery pack of mixed lithium and capacitors could solve the whole issue of range and charge time...but time will tell...lets see what tesla wizards can come up with....until then...

...tesla released some stats on battery life....if you use your battery from 100% to near empty almost every charge.......you will kill your battery in just a few years....drivers that charge to %70 and discharge to %30 get the best battery lifetime use.... by a large margin....also slow charging and not using fast charging had a big effect...... batteries would have to increase 5X in capacity for batteries to be a swap out for a dinosaur aviation ICE engine....even then a full charge would take over night....

....the video you posted was very preachy on the global warming religion running around these days.....i`m a believer of a different reason on why the ice caps on mars are melting...and its not cause of too many cars driving around...I include here a little of what I and many others believe is cause all the trouble....keep in mind as you watch this...that dot is the same size as the earth.....it gives you a perspective on what is the prime mover in our neighborhood...if you were standing on mars looking at the sun...this is what the earth would look like...

[svyolo]

We have been using ICE engines and batteries for 100 years. We are not about to achieve a huge breakthrough in either. Just the opposite. We are experiencing the "law of diminishing returns".

I am sure Bob's new electric plane will be a nice plane. Who knows, maybe i will build one. But I will put a gasoline powered engine in it an make it useful.

[zkelley2]

We've have tremendous improvements in both in the last 100 years. And the rate is increasing exponentially. Not slowing.

Breakthroughs are a myth. They don't happen in science or technology. What happens in the real world is a lot of small changes over some period of time that together are a very large difference than what came before. We see that in both ICE and batteries.
There's plenty of battery tech that has been done as a proof of concept is a ways from commercial production. Some of it will never come into productions, but the concepts and lessons learned will go on into what eventually will be much greater energy density batteries.

[svyolo]

Wow, I gotta dissagree. The "big" improvement has not been ICE engines, but the electronics that control them, and to a lesser extent the transmissions that convert their power to the wheels. I think we are very deep into the law of diminishing returns on ICE engines.

The vast majority of us chose Lycoming or Continental engines for our BH. Despite the cost, I don't think most of us think we should have spent our money on an engine 60 years newer, because it was a better engine.

I would bet a whole lot of money, that in my lifetime, there is no affordable electric propulsion option for light aircraft, with 4 hours endurance, plus reserve.
I think I have a bit over 30 more years to the average american male lifespan.

I hope I am wrong, but I wouldn't be my own money on it.