Electric Hybrid

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Don Hodges

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Just curious, but has anyone tried an electric drive with a remotely mounted generator. Might make for interesting weight and balance. Could possibly get the weight off the FWF. Opinions please.
 

Dan Thomas

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It's been discussed many times. For an airplane, anything that adds weight is unwelcome. Now, instead of driving a propeller directly with an engine, you'd have the weight of the engine, generator, electric motor and maybe batteries, along with all the failure points in the system.

Whether the weight is on the firewall of anywhere else, it has to be lifted, and lift requires power and structure. More weight requires more structure and more power.
 

wsimpso1

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Dan left out the power electronics for converting power from the generator and for the motor. Even more weight.

Billski
 

Mohawk750

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The UAV developers are deep into this idea but it's yet to be proven in the real world. It's doubtful it will scale to man carrying aircraft. In many cases the sensor payloads of UAV's make up a small percentage of the total weight and it's all about range and endurance.

It's hard to beat the power density of the internal combustion engine! And your performance gets better as you burn off fuel.
 

Samuli

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What about Equator's P2 Xcursion?

Quote:
"Although initial testing is done on our pure electric power drivetrain (batteries, controller and electric machine, which will also be an option for future customers, the P2 Xcursion was made to accomodate and test a new type of range extender based on a 57kW wankel rotary motor that can use bio based cherosene fuels. The system and components is a specialized drive train proprietary to Equator Aircraft. More info will follow on when we will make these components available to be purchased. " Prototype | Equator Aircraft

Equator Aircraft
Article about Equator P-2 at sustainableskies.org
 

Dan Thomas

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What about Equator's P2 Xcursion?

Quote:
"Although initial testing is done on our pure electric power drivetrain (batteries, controller and electric machine, which will also be an option for future customers, the P2 Xcursion was made to accomodate and test a new type of range extender based on a 57kW wankel rotary motor that can use bio based cherosene fuels. The system and components is a specialized drive train proprietary to Equator Aircraft. More info will follow on when we will make these components available to be purchased. " Prototype | Equator Aircraft

Equator Aircraft
Article about Equator P-2 at sustainableskies.org
Funny they don't give an empty weight for the version with the Wankel. The EW of the straight electric is already 1168 pounds. Perhaps they'd have to remove a bunch of the battery pack to compensate for the engine weight. Otherwise they'd lose pretty much all their useful load, or they'd have to raise the gross weight, not a good idea considering that Vso is already 52 knots/60 mph.
 

Mohawk750

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They have come a long way but the longest flight I saw mentioned was 17 minutes. No flights yet on the hybrid power so still not a real world solution to range extending an electric aircraft.
 

Dan Thomas

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They have come a long way but the longest flight I saw mentioned was 17 minutes. No flights yet on the hybrid power so still not a real world solution to range extending an electric aircraft.
Ah. Yet another website marketing yet another unproven airplane with unproven range.

I wish these outfits would get their ethics acts together and fully test and PROVE their designs (and manufacturing capabilities) before marketing them. Aviation has already been badly dirtied up by the likes of Bede and Moller and Icon and Terrafugia and a lot of other guys taking deposits based on little more than wishful thinking. The electric-airplane has provided a whole new venue for big promises with the potential for big disappointments.
 

Sockmonkey

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It could work if they went with something like a free piston linear generator. An engine specifically designed from the ground up to be a generator rather than standard engine configurations that aren't.
 

BJC

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It could work if they went with something like a free piston linear generator. An engine specifically designed from the ground up to be a generator rather than standard engine configurations that aren't.
I’ve never seen a commercial version of a free piston linear generator. Can you point out one for me?

Thanks,


BJC
 

Aesquire

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Steam turbine! Solar! Half of a hydrogen filled light transparent sphere is sprayed silver, with a black coil in the focal zone. Rotate to face energy source. Sized correctly wings are redundant.

Or Engine List 1 - Atomic Rockets I like the Solar Moth for those vacations to the Lunar Orbital Casino.

Practical hybrids that aren't military recon drones are probably a little easier. Less hanger space, anyway.
 
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Aesquire

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Seriously, it's a great idea, but simply using a Prius drive train is far too heavy. A light dedicated generator/engine is needed, the supercapacitor I haven't seen yet on Amazon, control electronics custom programmed for your exact configuration, and reliable enough that the self test on key turn is good enough.

The planet may soon find that the minerals currently used are in too short supply for the anticipated/mandated needs. Both the rare earth metals and Lithium.

Not trying to start an argument or be political, but today's available, commercially available, batteries are a dead end, a different chemistry is needed. Even the old iron acid Edison cells are less of a hazardous waste disposal problem, although the power density is too low to make engineers happy, but the Iron and other chemicals are in abundance. Maybe the promised Aluminum air battery?

Not to discourage! Just don't expect to duplicate the performance of an IC engine setup, specifically, range.

Or Stirling engines... Great for that desk toy that runs on top of your hot coffee cup, but forget it for your Lancair.
 

John.Roo

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ELFIN
RS.aero: elfin project
csm_Det_rangeextender1_b31a940af2.jpg

stemme_rangeextender_vorab2_9ce8548228-1.jpg
Info from web:
"Elfin can be fitted with an auxiliary range extender. The 60 kilogram (132 pound) under-wing mounted internal combustion engine and generator setup can deliver 30-35 kW continuously. At a normal cruise of 185 km/hr (100 knots or 115 mph) at 10,000 feet, the Elfin can carry its two passengers 1,000 kilometers, or 540 nautical miles – roughly six hours endurance. Fuel is carried in the center wing and the pod carrying the engine/generator can be mounted or demounted by a single person with a “rigging aid.” In operation, a single on/off switch enables or disables the range extender."
 

John.Roo

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DIAMOND AIRCRAFT
csm_HEMEP_PressRelease_Pic_1_44e3353420.jpg
csm_HEMEP_PressRelease_Pic_2_1252be5b88.jpg
Info from web:
"Two electric engines have been added on a forward canard, which combined can generate 150kW of take-off power. The diesel generator is located in the nose of the aircraft and can provide up to 110kW of power. Two batteries with 12kWh each are mounted in the rear passenger compartment, and act as an energy storage buffer.
Pure electric, the aircraft has an endurance of approximately 30minutes. The hybrid system extends this to 5 hours.
"
 

John.Roo

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In my opinion is a question of system efficiency.
Electric propulsion:
80% propeller
85% electric motor (I don´t want to use 90-95% "laboratory efficiency")
95% controller (if has to be cooled than it has no 100% efficiency)
+something for wiring (not important at the moment)
All together it means you take 100 kW from battery and you get finally +-65 kW.
From 65 kW power you get some thrust etc....

Hybrid:
Now lets forget low efficiency of IC getting 35-40% from fuel energy.
We suppose 100 kW on shaft.
It means:
85% generator (I am very optimistic)
95% controller
So theoretically you get from 100 kW arround 80 kW recharge power going to batteries (again - this is very optimistic expectation).
From batteries you go again thru controller and motor and prop.
80 kW * 0,95 (controller) * 0,85 (motor) * 0,80 (prop. eff.) = you get +-52 kW.

Adding 35-40% efficiency of internal combustion engine it would show that is real energy waste.... We (pilots) are lucky that something like fuel exists - really amazing energy source.

Possible "hybrid" solution?
Keep electric propulsion as main propulsion system with limited endurance of 60-90 minutes (achievable with actual technology).
Add small combustion engine as "range extender", only not with generator but directly connected to prop. For this you need only really small engine - as it will be used only for cruise flight at optimal (ideally best L/D) speed. For example - MTOM 600 kg "motorglider like" airplane will need 15 kW engine for reasonable cruise speed.
If is all on one prop with some clutch or simply just as extra pod (pylon etc.) doesn´t really matter. Important will be to achieve as low as possible drag (ideally with folding prop).
However would be nice to make it simply removable because majority of aeroclub and private "sport" flights are 60-90 minutes long :)
 

Dan Thomas

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ELFIN
RS.aero: elfin project
View attachment 107183

View attachment 107184
Info from web:
"Elfin can be fitted with an auxiliary range extender. The 60 kilogram (132 pound) under-wing mounted internal combustion engine and generator setup can deliver 30-35 kW continuously. At a normal cruise of 185 km/hr (100 knots or 115 mph) at 10,000 feet, the Elfin can carry its two passengers 1,000 kilometers, or 540 nautical miles – roughly six hours endurance. Fuel is carried in the center wing and the pod carrying the engine/generator can be mounted or demounted by a single person with a “rigging aid.” In operation, a single on/off switch enables or disables the range extender."
Once again, marketing efforts based on unproven speculation, though by a reputable company for a change. The only actual photo of anything related to the real thing is a picture of some molds for the fuselage. Obviously there is no actual airplane yet, with or without any range extender.
 
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