Pipistrel Velis Electro

Website says they get up to "50 minutes with VFR reserve." It's got a lot of wing and nearly 80 HP with gross limited to 1320 lbs. I'll be interesting to see what your friend has to say about it.
 
Daleandee said:
Website says they get up to "50 minutes with VFR reserve." It's got a lot of wing and nearly 80 HP with gross limited to 1320 lbs. I'll be interesting to see what your friend has to say about it.
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Yes, it's 90 min charge, so about an hour with reserve. I suspect it's good for ab-initio flight lessons or local sightseeing, but it's obviously not up to transportation.

OTOH, it's possible that the dispatch rate is much higher than with our ICE planes, since there's less to break in the powerplant. Most flight schools I've seen to always have a few planes off the line for protracted periods (and thus not earning revenue).

I'll report back on his experience.
 
David Megginson said:
Yes, it's 90 min charge, so about an hour with reserve. I suspect it's good for ab-initio flight lessons or local sightseeing, but it's obviously not up to transportation.

OTOH, it's possible that the dispatch rate is much higher than with our ICE planes, since there's less to break in the powerplant. Most flight schools I've seen to always have a few planes off the line for protracted periods (and thus not earning revenue).

I'll report back on his experience.
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With a 3 hour charge between flights, I doubt the dispatch rate is a plus.
 
asicer said:
Pipistrel's recommendation: Buy more planes...

View attachment 100267
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I find this concept frustrating... if they offered a modular battery pack that could be quickly removed/installed, then all you would need is two extra batttery packs and you could fly pretty much nonstop except when swapping packs.


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David Megginson said:
Yes, it's 90 min charge, so about an hour with reserve. I suspect it's good for ab-initio flight lessons or local sightseeing, but it's obviously not up to transportation.
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I wonder how many TO/Landing cycles they include in that 90 minutes? Any time you stop/start, you're wasting a LOT of energy.
 
kyleb said:
I wonder how many TO/Landing cycles they include in that 90 minutes? Any time you stop/start, you're wasting a LOT of energy.
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Queue up all the regenerative braking fallacies here
 
jrollf said:
I find this concept frustrating... if they offered a modular battery pack that could be quickly removed/installed ...
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They do. In fact, they recommend that very thing ... have spare batteries charging on the ground while you fly

EDIT: Sorry, I know you can swap batteries on their Alpha Trainer. Not sure about the Velis ...
 
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Stephen Poole said:
EDIT: Sorry, I know you can swap batteries on their Alpha Trainer. Not sure about the Velis ...
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upload_2021-9-20_16-41-39-png.100267
 
Salty said:
With a 3 hour charge between flights, I doubt the dispatch rate is a plus.
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What always seems to be missing in discussions about electrically powered aircraft is how they will be maintained. A flight school that purchases the aircraft will have to employ technicians with specialized training, and I suspect that right now the organization and syllabus for that training is not adequate to train enough mechanics for multiple schools. How many months will a training class take to graduate qualified techs?

Assessing the maintenance requirements, there are safety issues with the 345 volt DC battery pack. The procedure for inspecting battery connections exposes the mechanic to that voltage, and an inadvertent slip of a wrench could cause burns and even electrocution. Mechanics unfamiliar with high voltage battery and electrical systems will need to work carefully.

A significant amount of knowledge will be required to service the aircraft's power system. The method of providing variable thrust with the motor is unclear. Literature produced by Pipistrel indicates an AC inverter is used to supply electrical energy to the motor, but in the same document it says DC voltage is the method used to operate the motor.

https://www.pipistrel-aircraft.com/aircraft/electric-flight/e-811/

Regardless of the method employed, the motor will have a sophisticated electronics package. The technician's training will need to be specialized, as the propulsion package likely utilizes onboard diagnostics and a modular parts replacement scheme. That would require an expensive parts inventory for the school.

There is a liquid cooling system for the two battery packs, with one located behind the engine and the other behind the pilot and instructor seats. Their location appears to make swapping a discharged battery pack for a fresh one difficult. Specifics for that procedure are not provided in manuals available online.

Pipistrel's solution to recharge time is simple; buy more aircraft. As flight schools typically operate with a slim profit margin, this method is unlikely to find favor with the schools. It appears to me that acquisition and maintenance costs of the aircraft will limit its widespread use in training.

I suspect the aircraft will find favor with ab initio training schools financed by major airlines. Independent schools...not so much.
 
kyleb said:
I wonder how many TO/Landing cycles they include in that 90 minutes? Any time you stop/start, you're wasting a LOT of energy.
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From what I read elsewhere, they recharge between lessons (60 min fast charge from flat, so less than that with 1/3 reserve remaining), so there wouldn't normally be many full stop cycles on a single charge. And the plane does a small amount of energy recovery on descent/deceleration (not much, obviously, compared to an electric car).
 
Salty said:
Queue up all the regenerative braking fallacies here
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David Megginson said:
From what I read elsewhere, they recharge between lessons (60 min fast charge from flat, so less than that with 1/3 reserve remaining), so there wouldn't normally be many full stop cycles on a single charge. And the plane does a small amount of energy recovery on descent/deceleration (not much, obviously, compared to an electric car).
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Didn't take long.
 
kyleb said:
I wonder how many TO/Landing cycles they include in that 90 minutes? Any time you stop/start, you're wasting a LOT of energy.
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Can you explain your reasoning? Obviously it takes more power to initiate a full power climb than cruise flight, but also can be near zero (or negative) power during descent. Electric motors don't generally suffer from largely increased losses at different power settings, other than very low power (however these low power settings also do not consume much energy, and don't last that long in either cruise or pattern work). See the quote from the linked article, which has a figure 1 showing that larger motors have nearly 100% efficiency down to 10% power. Electric motors also do not have any losses from actual startup or shutdown of the prop, no losses from having to warm up the engine on a cold morning, waiting for a traditional run-up, etc.

"Most electric motors are designed to run at 50% to 100% of rated load. Maximum efficiency is usually near 75% of rated load. Thus, a 10-horsepower (hp) motor has an acceptable load range of 5 to 10 hp; peak efficiency is at 7.5 hp. A motor’s efficiency tends to decrease dramatically below about 50% load. However, the range of good efficiency varies with individual motors and tends to extend over a broader range for larger motors (75-100hp), as shown in Figure 1. A motor is considered underloaded when it is in the range where efficiency drops significantly with decreasing load. Figure 2 shows that power factor tends to drop off sooner, but less steeply than efficiency, as load decreases."

https://www.energy.gov/sites/prod/files/2014/04/f15/10097517.pdf
 
It hasn't happened in this thread yet, but I do think there's no need for electric planes to become a controversial point in aviation forums. While there's a lot of speculation, I think two things are pretty clear:
  • Purely-electric planes have reached the point that they have adequate performance for basic, ab-initio training (e.g. one-hour lessons on elementary flying maneuvers).
  • Purely-electric planes won't ever displace high-performance ICE aircraft, because there's a hard theoretical energy:density limit that even future battery improvements won't be able to cross.
So while battery-powered planes might pose a "threat" to entry-level trainers like the Cessna 152, Diamond DA-20, etc — and maybe some day as far up the food chain as older Cessna 172s or lower-horsepower Piper PA-28s — they'll never displace your beloved Bonanza, C182, etc (it would have to be something else, like hydrogen power). So there's no need for anyone to dig a bunker and prepare for a long siege, because it isn't coming.
 
Matthew Rogers said:
Can you explain your reasoning?
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Sure. The battery has limited capacity. Every takeoff and climb to pattern altitude requires the airplane to expend a portion of that energy. Landing wastes most of that potential and kinetic energy you've "bought" with the energy out of your battery. If the airplane has a regen feature, you get a little of it back, but probably not a lot - the prop is designed to produce thrust, not recover it. Then you have the loss of energy due to putting the airplane in a high drag configuration (flaps) and due to braking action. You won't get any of that energy back.

So the airplane is gonna be takeoff and landing cycle limited. They all are (even the recips), but today's batteries start with relatively little energy, so it only figures they will have less ability to do takeoff and landing cycles than conventional trainers.
 
Matthew Rogers said:
Can you explain your reasoning? Obviously it takes more power to initiate a full power climb than cruise flight, but also can be near zero (or negative) power during descent. Electric motors don't generally suffer from largely increased losses at different power settings, other than very low power (however these low power settings also do not consume much energy, and don't last that long in either cruise or pattern work). See the quote from the linked article, which has a figure 1 showing that larger motors have nearly 100% efficiency down to 10% power. Electric motors also do not have any losses from actual startup or shutdown of the prop, no losses from having to warm up the engine on a cold morning, waiting for a traditional run-up, etc.

"Most electric motors are designed to run at 50% to 100% of rated load. Maximum efficiency is usually near 75% of rated load. Thus, a 10-horsepower (hp) motor has an acceptable load range of 5 to 10 hp; peak efficiency is at 7.5 hp. A motor’s efficiency tends to decrease dramatically below about 50% load. However, the range of good efficiency varies with individual motors and tends to extend over a broader range for larger motors (75-100hp), as shown in Figure 1. A motor is considered underloaded when it is in the range where efficiency drops significantly with decreasing load. Figure 2 shows that power factor tends to drop off sooner, but less steeply than efficiency, as load decreases."

https://www.energy.gov/sites/prod/files/2014/04/f15/10097517.pdf
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According to the Pipistrel site, the battery life is quoted for operations near the aerodrome like touch-and-go's, not for point-to-point flight.
 
I think it’s pretty cool that a mfg is actually producing full electric aircraft. Not my preferred power source, but very cool that it exists. It will get better quickly from here, from a design standpoint. Battery tech is getting better, but we live in an era when no one can wait for 15 minutes for anything, so the troglodytic luddites will talk their incessant mess.
 
Daleandee said:
"troglodytic luddites"

Hey! I resemble that remark! ;)
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Don't worry. I still like using an E6B and round gauges. :) But I think maybe electric trainers might be a way to get more people into aviation more cheaply (and to help flight schools, most of which are usually teetering on the edge of insolvency), and that can't be a bad thing for any of us. We want to get them thoroughly hooked before they realise how much aviation really costs.
 
Lachlan said:
I think it’s pretty cool that a mfg is actually producing full electric aircraft. Not my preferred power source, but very cool that it exists. It will get better quickly from here, from a design standpoint. Battery tech is getting better, but we live in an era when no one can wait for 15 minutes for anything, so the troglodytic luddites will talk their incessant mess.
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What's the fancy term for those that get excited about "new tech" that performs in every way worse than the old tech?
 
I think electric airplanes have reached the point they can perform a single one hour lesson before they have to go back on the charger for an extended period.

if you can't swap the batteries because they're in a bad position, it sounds like a design flaw to me.

Salty said:
What's the fancy term for those that get excited about "new tech" that performs in every way worse than the old tech?
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The term is "early bleeders". Or early adopters if you're optimistic about it.
 
Lachlan said:
I think it’s pretty cool that a mfg is actually producing full electric aircraft. Not my preferred power source, but very cool that it exists. It will get better quickly from here, from a design standpoint. Battery tech is getting better, but we live in an era when no one can wait for 15 minutes for anything, so the troglodytic luddites will talk their incessant mess.
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What I wish the industry would do is develop hot swappable standardized modular battery packs. Then you could have batteries charging while your flying (or driving!). Land, swap packs in a few minutes, then off flying again. Heck, airports could stock them so you could go on cross countries.

I've thought the same thing about electric cars. Modular battery packs that can be swapped quickly. Imagine one could pull into a "gas station" swap battery packs, pay for the for the differnce in charge levels... then back on the road in a few minutes fully charged.

Alas companies love Apple's approach in today's world... make everything proprietary. Imagine if ICE engines were a new development in today's world... Ford would require "Ford Gas", Chevy "Chevy Gas", BWM "BWM Gas" etc, because be damned standards, someone else might make money.

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bflynn said:
I think electric airplanes have reached the point they can perform a single one hour lesson before they have to go back on the charger for an extended period.

if you can't swap the batteries because they're in a bad position, it sounds like a design flaw to me.



The term is "early bleeders". Or early adopters if you're optimistic about it.
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It's not just the position, according to Pipistrel, but the switch to water cooling and the weight (two batteries at 70 kg/155 lb each) that would preclude fast field swapping by an instructor or line staff between students.

I also support modular, field-swappable batteries for all electric vehicles — I think that's the future, rather than lots of custom charging stations — but I think Pipistrel just couldn't pull it off and get EASA certification (via redundantly batteries with failover) and adequate endurance, at least not this iteration.

Battery tech should have improved by the time they release their next model, and then they can decide how to trade off between longer endurance and faster turnaround, based on the feedback they got from their customers this time around.
 
Daleandee said:
I have no doubt that electric aircraft for limited use will be available fairly soon. I would have thought the hybrid approach would have been used more on the way over to full electric. See what Diamond was doing:

https://www.diamondaircraft.com/en/...flight-multi-engine-hybrid-electric-aircraft/
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I'm surprised anyone's trying a hybrid approach for planes, because that just doubles the weight: you're carrying the batteries and some kind of ICE engine with its fuel. Maybe some clever person will figure it out, though.
 
David Megginson said:
I'm surprised anyone's trying a hybrid approach for planes, because that just doubles the weight: you're carrying the batteries and some kind of ICE engine with its fuel. Maybe some clever person will figure it out, though.
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Think about it this way, though. Your 172 needs 160 hp for takeoff and climb, but cruises all day on 100 hp. So put a 60 hp electric boost motor and relatively small battery in it in addition to a 100 hp recip. Recharge the boost battery inflight.
 
bflynn said:
I think electric airplanes have reached the point they can perform a single one hour lesson before they have to go back on the charger for an extended period.

if you can't swap the batteries because they're in a bad position, it sounds like a design flaw to me.

The term is "early bleeders". Or early adopters if you're optimistic about it.
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Absolutely. They have a while before they'll be ready to cross the chasm to the early majority on the Rogers innovation adoption curve. Most of the adapters right now well either be enthusiastic experimenters, or people with special needs that they can't meet any other way (for example, cutting the cost of training in the face of high European avgas prices).

I could also see a case for electric planes right now in remote northern Canadian communities where there are no roads and avgas is difficult to get — sometimes it's even flown in — but there's usually still electricity.

While cold weather might reduce battery performance, it won't cause any problem for starts (no more need to drain the oil and bring it inside overnight, for example).
 
I don’t see how swapping out 10k in batteries is feasible. It’s not like it’s a $20 propane tank that’s pretty much indestructible. Everybody treats their cars differently. I guess it could work, but I think actually removing and replacing them is an even bigger issue. This tech needs every little thing it can get to be viable even in a niche. Making it removable makes it not work.
 
kyleb said:
Think about it this way, though. Your 172 needs 160 hp for takeoff and climb, but cruises all day on 100 hp. So put a 60 hp electric boost motor and relatively small battery in it in addition to a 100 hp recip. Recharge the boost battery inflight.
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A 100 hp recip weighs close to 200 lb, IIRC. The batteries in the Pipistrel weigh 300 lb and go up to a bit under 90 hp for 1½ hours (probably not at full power the whole time), while that 100 hp engine will need 100–150 lb of avgas to run for any amount of time. I'm sure engineers will figure out slight optimizations for all of those, but I just can't see any way of making the numbers add up for a hybrid solution in a light aircraft.

If were to try one, I would have only the electric powertrain, would add the lightest-weight diesel-powered generator or alternator I could find, and run it to recharge the batteries as needed in flight. But still, I think the weight of the extra fuel would be too much.
 
kyleb said:
Think about it this way, though. Your 172 needs 160 hp for takeoff and climb, but cruises all day on 100 hp. So put a 60 hp electric boost motor and relatively small battery in it in addition to a 100 hp recip. Recharge the boost battery inflight.
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Seems the fact that some big names and companies are working on this approach indicates that it has some merit to it.

I don't have any of the answers but battery power alone isn't gonna work for any serious flight time in much over a two seat glider type plane. When the technology improves we'll see some improvement.

Remember the reason for this has nothing to do with airplanes per say as much as it has to do with the idea of some we can make everything electric and save the planet. Some electric car owners pride themselves in their zero emissions vehicle but look the other way when driving past a coal or oil fired power plant ... :rolleyes:
 
asicer said:
"Venture capitalist"
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I wouldn't do that at this point in market maturity, because I wouldn't want to surrender so much of my control and equity. I'd try to limit myself to bootstrapping and angel investors. VC's are useful only when you need huge sums of money to scale up fast, but there's no big market to scale up in yet.
 
Daleandee said:
Some electric car owners pride themselves in their zero emissions vehicle but look the other way when driving past a coal or oil fired power plant ... :rolleyes:
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I agree, though I'm probably coming from a different part of the political spectrum. Personal electric cars are bad for the environment; they're usually a bit less bad than ICE cars, but they're not actually good, especially if you live in a country like the United States or China that still uses coal for a lot of its power generation.

From a purely environmental PoV, walking is the best ground transportation, then cycling (which requires more road/path infrastructure), then public transit (assuming adequate ridership), then last are powered personal vehicles — of any kind.

And don't take this as a personal judgment, because like everyone else here, I fly an airplane, so I'm in no position to throw the first stone.
 
Daleandee said:
I don't have any of the answers but battery power alone isn't gonna work for any serious flight time in much over a two seat glider type plane. When the technology improves we'll see some improvement.
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We're not too far apart on this. I believe that battery technology has two doublings left, then it will hit the absolute chemical energy-density wall for a non-consumable power source.

That means that we could some day have a plane like the Pipestrel Velis Electro with 6 hours' endurance instead of 90 minutes, or alternatively, one that carries a little more or flies a little faster with 3–4 hours' endurance.

This is bringing us past powered gliders into Piper PA-28-140, Cessna 150, or even early Cessna 172 territory, but that's the furthest battery powered planes will ever be able to go, and even that assumes a lot of complex innovation that hasn't happened yet.
 
David Megginson said:
And don't take this as a personal judgment, because like everyone else here, I fly an airplane, so I'm in no position to throw the first stone.
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No harm, no foul. I'm not married to any of these ideas.

I do believe that, at this time, electric planes and cars have the potential to cause more damage that isn't fully revealed because of the manufacturing process and disposal of old batteries and products used. Of course all of this will improve over time but we ain't there just yet.
 
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