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Fisher Flying Products to spin off company offering electric propulsion system for the light plane market, starting at $10,000 for 25kW

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jandetlefsen

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It appear like they partner with Gabriel DeVault, who worked in Zero Motorcycle's R&D department for 6 years and is currently head of drivetrain development at ZeroAvia, the company that is developing a hydrogen fuel cell powered electric plane.
 
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Vigilant1

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The $10,000 package includes a motor that produces 25KW (33HP) peak, 20KW (26HP) continuous. The batteries for that system/price total 5.6KWH, which gives 17 minutes of power at that 26HP output. So, in that case, 26 HP continuous--for 17 minutes.

The video informs us that "we've reached a tipping point where internal combustion systems can no longer compete on increased range alone."

Anyway, could be fun for the right motorglider.
 

jandetlefsen

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So, in that case, 26 HP continuous--for 17 minutes.
26 HP is the max continuous rating. They aim for 45 minutes flight time of their planes. AFAIk they want to electrify their whole range and they don't sell motorgliders.
 
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12notes

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20kW for 2 minutes takeoff and climb uses 0.67kWh, leaving 5 kWh, rounded up. A 43 minute flight after that would require a cruise power of 7kW (9 hp), or 35% throttle.

Note that this calculation is unreasonably optimistic towards the electric system, never using peak power, a very short climb, and left nothing for reserve. I don't think 35% of continuous power (27% of peak) is a reasonable expectation for cruise flight, and I'm not sure 9hp would provide a reasonable speed or range if it is even enough to maintain altitude at that power. And the whole flight would be well under 2000' AGL, likely closer to 1000', unless there is a plane that gets a 1000fpm climb out of 26hp. I genuinely don't know on that last part, please inform me if there is

A slightly more reasonable calculation: 26kW for 3 minutes climb would use 1.3kW, leaving 4.3kWh for cruise. Reserving 0.5kWh for a single go around attempt (1 minute climb + enough for a very close pattern), would leave 3.8kWh for cruise. 60% of continuous power is 12kW (16hp), leaving enough for 19 minutes of cruise, total flight time of 23 minutes, including the reserve.
 

daveklingler

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I think Fisher's headed in the right direction for their particular market. It's not inconceivable to me that the majority of their customers like to go up for about an hour a day. Batteries that will support that mission should arrive over the next year or so.

Two hours is much tougher. Over the next few years we'll see a fairly big jump in battery power densities, including at least a half-dozen brands of solid batteries with much higher densities than are available now. There's at least one Chinese company in production on solid batteries, and VW's Blackstone said last month that they're planning their first mass production facility for a 3D-printed solid battery.

Call it 1-2 years before Fisher can go out and buy a solid state battery that will give them one-hour flight times, and 3-5 years before two hours becomes a realistic design goal, at least IMO.
 

jandetlefsen

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20kW for 2 minutes takeoff and climb uses 0.67kWh, leaving 5 kWh, rounded up. A 43 minute flight after that would require a cruise power of 7kW (9 hp), or 35% throttle.
The way i understood the video is that you gonna have two batteries 5.2 kWh each.

EDIT: It does seem possible. One battery pack should weigh around 25kg each, on a cell level they should cost around 600$, so well within the $10k drivetrain budget. The smaller single seater have a useful load of around 200kg if you subtract the Rotax engine. probably even a bit more by removing all the supporting system for the engine. EV propulsion system should be well under 100kg, maybe 70-80kg. leaves enough weight for the pilot. All together not in the realms of the impossible.
 
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BJC

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I think Fisher's headed in the right direction for their particular market. It's not inconceivable to me that the majority of their customers like to go up for about an hour a day. Batteries that will support that mission should arrive over the next year or so.
I hope that you are right: I’ve been reading that claim for five years now.


BJC
 

TFF

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Like the RC world has to learn, you have to leave quite a bit of capacity unused so the battery chemistry doesn’t die. The harder the draw, the more you need to leave. Tesla’s don’t drag race every day, but a takeoff is a drag race. Real batteries will need to be 30-50% larger than used. One mistake and you buy a new battery. Cars can monitor charge and cut back. Airplane you can’t have the interference, so it will be for the pilot to keep track.

Peter Stripol’s latest is stepping forward. The only way RC planes out do the IC engines is the weight/ strength that can be removed from the airframe because of engine vibration. Removing this from man carrying planes will be harder. I don’t like picking up modern RC Pattern planes because I can stick my thumb through it with a wrong grip.

Another thing and I hope it doesn’t happen. Plenty of people have been hurt by high voltage batteries in fork lifts and stuff. I believe they have an industry voltage limit for Personal safety. Will this happen in aviation or will it be as much performance as you can go until something happens?
 

12notes

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The way i understood the video is that you gonna have two batteries 5.2 kWh each.

EDIT: It does seem possible. One battery pack should weigh around 25kg each, on a cell level they should cost around 600$, so well within the $10k drivetrain budget. The smaller single seater have a useful load of around 200kg if you subtract the Rotax engine. probably even a bit more by removing all the supporting system for the engine. EV propulsion system should be well under 100kg, maybe 70-80kg. leaves enough weight for the pilot. All together not in the realms of the impossible.
I did not interpret the video that way. However, let's assume you're right, but I'm also going to drop the absurdly optimistic scenario I used above. So we'll use the correct cruise 65% of max power that Fisher recommends for it's gasoline engines, and let's use 800 ft/min climb rate, the maximum of any of their lower powered aircraft. And let's increase it to a slightly more sane, but still very risky, reserve for two 1000' climb, 2 minute cruise patterns.
25kW for 3 minutes climb (to 2400' AGL) would use 1.25kW, leaving 9.15kWh for cruise. Climb to 1000' will take 1.25 minutes at full power, using 0.52 kWh, 2 minutes at 65% power uses .54kWh, for a power usage of 1.06kWh per go around. A 2 go around reserve will leave 7.03kWh. 65% of max power is 16.25kW , leaving enough for 26 minutes of cruise, total flight time of 35.5 minutes, including using all of the reserve. This scenario is still optimistic, I'm not flying a plane until it has only enough fuel for exactly 2 go arounds, and I don't know many pilots that would volunteer to do so. A 45 minute total flight, using the climb and all of the reserve, would require a cruise power setting of 46%. Keeping the reserve capacity in , well, reserve, then the power setting would need to be 38% for cruise.

Which Fisher plane did you do these calculations on? What did you use for engine weight? I didn't do a extensive search, but the lower powered ones didn't have a useful load of 100kg, and their complete engine weight (w/ exhast, gearbox, etc) was in the 35kg range. The highest gross weight of all the FP-x0x planes was 540 lbs (245kg), a 200 kg available for drivetrain and pilot would only leave 45kg for the entire rest of the aircraft. The Avenger and Dakota would leave just 72 kg for the airframe. Their planes that can have 200kg available require between 50-65 hp, requiring much more battery and motor.

I like electric planes, and want them to succeed, but the ones that use bad math and questionable physics need to stop and promote reality. Plausible sounding BS isn't acceptable. I don't fault Fisher airplanes, I'm glad they're offering this package, but they need to be realistic about what they're selling. I do blame the guy who sold them this based on fantasy numbers.

EDIT: recalculated to use correct 25kW max power instead of 26kW used originally.
 
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BBerson

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Dale Kramer's electric Lazair flew several times around the pattern at Airventure. Even with the wheels/amphib float it was probably far more efficient than a Fisher.
 

Vigilant1

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And, can we use all the available battery capacity and expect a reasonable service life from them? If we are interested in the economics of this idea, we'd need to see the guaranteed number of charge/discharge cycles and the replacement cost for the batteries, then amortize it to $$/flying hour. When we looked at the electric Pipistrel, this came out to $31 per hour (to save $9 per hour in fuel cost . . . ). That's a hard case to make, if we care about costs.
 

Riggerrob

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Fisher seems to be on the right track to electrify small airplanes. Even if it takes a few more years - than forecast - they are still innovating in the right direction. I can foresee plenty of ultralight pilots who want to "get their knees in the breeze" for 45 minutes or an hour every evening.
Also consider that few primary flying lessons exceed one hour.
The first generation of electric conversion kits will be straight, drop-in replacements for Polini or Rotax engines. Later conversion kits will offer greater varieties of configurations.
How much does a Fisher electric motor, propeller and mount weight? ... if I want to bolt it to the aft end or wingtip of a new design?
We will mount batteries wherever it is convenient for balance, but also have to consider the extra weight of longer power cables connecting batteries to the motor.
 

pictsidhe

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Dropping an electric conversion into most current Ultralights will be disappointing. They are designed for high drag to get decent climb rate. It's just the rules work for Ultralights.
Older designs that flew with 15hp are needed.
 
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