Electric PA-28 ?

[Garfly]

 

 

 

https://www.avweb.com/air-shows-events/farnborough/cae-piper-to-develop-archer-electric-conversion-kit/

 

https://www.cae.com/news-events/press-releases/cae-launches-electric-aircraft-modification-program-with-piper-aircraft-inc

 

 

 

[Thruster88]

The PA-28 has the best fuel tanks for electric conversion of an existing airframe. Replacement of the Lycoming O-360 with a lighter electric motor and limiting it to two pilots or 200kg in the in cabin should allow about 300kg of batteries. Enough for 60 mins of flight? 

 

[RFguy]

PA28 is not a good candidate since it is draggy and heavy. however !

assuming it takes 100HP for S&L flight, 75kW, and put a CS prop on it so it can get off the ground with reduced TO power (say 140 hp) ,

 

75kW  for an hour is 75kWh   x 3.6 =  270MJ ( about 21 ltrs of avgas after efficiencies) 

assume motor efficiency 90 %, so input = 83kW.  or easy 83kWh for an hour. x 3.6 = 300MJ

 

Best Graphite electrode  Lithium Ion battery  is about 250 Wh/kg  = 0.9 MJ /kg so 333kg batteries

Best SiC electrode  Lithium Ion battery  is about 450 Wh/ kg =  1.6 MJ /kg so 188kg batteries (now in production)

Best LiFEPO4 battery : 0.6MJ/kg so 500kg batteries

Best Lithium Sulphur battery (early production ) currently about 1.2 MJ/kg so 250kg batteries

 

 

 

 

 

 

 

Edited July 22, 2022 by RFguy

[spacesailor]

Thats a lot of " avgas " , ( 188 kg batteries  )

Will they Ever get to the IC engine efficiency. 

One hours flight was GOOD for the " Wright brothers " but now we all want ,

MORE

spacesailor

[RFguy]

Modern Battery efficiency is very high. > 90%. just storage performance.

Stuart, O360 is about what 140kg with accessories?  PA28 about 50 gallons from memory ? 140kg. 

electric kit < 50kg, so there is 90kg to play with for weight in the front, 90+140+70kg without bags or rear pax so yeah 300kg. you are right.

[Garfly]

I gather they're only thinking of it as a basic trainer so 2 POB and one hour could work, I guess.

Anyway, they seem serious.

[spacesailor]

Put that electricity into a purpose built airframe, and you coud/would double that one hour battery life.

spacesailor

[RFguy]

83kWh of batteries is likely USD$100/kWh , so including the necessary conditioning, probably a USD12k battery . probably 20k for the motor and controller if you dont put the word aviation in front of it. .  maybe much  less because there is much more scope for a heavier motor for a heavier airplane and thus doesnt use as many rare earths etc.

as you lot know I have done the numbers on this for many other instances already..

 

the advantage is that there are many PA28 airframes available. I mean they are like shopping carts at the local creek. Nothing wrong with them either.

 

 

 

 

[turboplanner]

Why would you bother to go to the expense when the current version has such a low prime and operating cost and a three-State genuine range?

 

[RFguy]

and people wont get the training they need on real planes with combustion engines.

 

[facthunter]

Handling complex IC piston engines well is not many pilot's strong point.  Electric will be safer, I doubt any existing airframe is very suitable for electric conversion except as a test bed or interim situation. The airframe has to be worth spending the money  on and be safe structurally.. Batteries are a dense concentrated load. Fuel at about .73 kg/ liter isn't. Nev

[Garfly]

1 hour ago, turboplanner said:

Why would you bother to go to the expense when the current version has such a low prime and operating cost and a three-State genuine range?

 

I think you pick up on the reasoning (economic and technical) in CAE's own blurb:

 

“The development of this technology is a first for CAE. As an engineering powerhouse and one of the largest Piper Archer® operators, CAE is uniquely positioned to make electric-powered flight a reality at our flight schools and beyond. CAE’s partnership with the Government of Canada and the Government of Quebec for investment into R&D has enabled us to boldly look to the future and prepare our electric aircraft for take-off,” added Parent.

“Piper Aircraft is excited to support CAE’s development of an electric aircraft modification conversion kit for the Piper Archer®”, said Piper Aircraft President and CEO, John Calcagno.  “With 28,000 aircraft in global service, the PA-28 is the ideal platform for real world flight training curriculums and professional pilot training programs like CAE’s.  Piper Aircraft is focused on aviation’s commitment to greenhouse gas reductions and as such, we look forward to collaborating with CAE on the integration of an electric propulsion system for the Piper Archer®.

[RFguy]

best Lithium Graphite anode specific gravity  is about 3..... so quite dense.

 

really needs designed from the ground up, and distributed carefully. 

volumetrically - you'd probably 1/4 fill a fuel cell with batteries .

they take the place nicely of metal in the front.

 

 

[RFguy]

it doesn't need any R&D to do it, principals and materials are well understood and readily available.

I wonder how much those new SiC nanowire lithium batteries are .

[Garfly]

14 hours ago, spacesailor said:

Put that electricity into a purpose built airframe, and you coud/would double that one hour battery life.

spacesailor

I doubt that truism would have eluded them.  It's clearly an interim measure.  Better to spend a few mill moving forward on this experiment than a few bill on a clean sheet project when, either way, a lot of the tech will be obsolete in a matter of years.  (How ironic, though, that a 60 year old airframe design is being re-purposed for the project. When the Cherokee was born, the Wright Flyer was a 60 year old design!!) 

 

As the ABC reported this week even pilots may be obsolete sooner than we think:

 

Regional councils back plan for electric air taxis during 2032 Brisbane Olympics as 'future' of transport

https://www.abc.net.au/news/2022-07-21/electric-air-taxis-coming-to-south-east-queensland-2032-brisbane/101256380

 

 

 

Edited July 23, 2022 by Garfly

[RFguy]

I would be hesitant to fly with a Lithium Cobalt or Lithium Nickel containing battery- they get rather unhappy if they get hot. think  fire.

 

Lithium Manganese oxide are nice . and have good energy density

 

Lithium Phosphate are very safe. but lower energy density.

 

Lithium Sliicon-Carbon nanowire though is there the real action is for density and performance and safety.  Early production now, 30-50% better than current batteries is a breakthrough.

 

https://amprius.com/technology

 

this is a reasonable breakthrough for tech, and makes a 1 hour trainer about 50% easier.

at around 450-500 Wh/kg--- about 2x ahead....

 

[facthunter]

Just imagine the extra time saved for Instructors and pupils. No warm up mag checks Temps and alternator monitoring etc. Of course a separate qualification would be necessary for the Petrol engines Nev

[RFguy]

Good points Nev.

Like I said, if someone wants to donate a suitable airframe, I'll do the other half....

Good option  is a Jab LSA55 or J120 or SK.  they're all inbound tanks so batteries go into the front in the cowling and where the 65 litres of fuel was behind the seats

Edited July 23, 2022 by RFguy

[turboplanner]

7 minutes ago, facthunter said:

Just imagine the extra time saved for Instructors and pupils. No warm up mag checks Temps and alternator monitoring etc. Of course a separate qualification would be necessary for the Petrol engines Nev

Have you flown an RC electric aircraft?

Don't forget with electric 100% of torque is available at start.

Much of what a student learns at the beginning of his/her training is not available with electric/after the electric hours the person gets into an ICE airctaft and .................

[RFguy]

I'd probabaly use a non rare earth motor, and one that doesnt have the word aviation on it.

Something else, with high RPM rather than semi -custom expensive low RPM motor  and a Rotax  3:1 or 4:1  gearbox or something with a customized e-props prop..

 

[spacesailor]

Someone bought at auction, a ' powered glider ' ( same time as roulettes auction  ).

Very quick conversion l should think .

if a pilot trains in an electric plane, they would Miss that ' kick in the pants ' thats missing in IC aircraft. 

Except for " Merlin powered Spitfires ". ( they say " opening the throttle to quick will flip the plane ).

spacesailor

 

Edited July 23, 2022 by spacesailor
Spelling

[facthunter]

Why complicate things? An electric motor can be inside a car wheel. Gear boxes use up power. (Chains are better but nothing is BEST)  Nev

[RFguy]

if you were doing it where you had economies of scale , sure go with a custom motor. Otherwise those custom low revving superlight motors are about 5x the cost of the specific motor and not much heavier.....

[onetrack]

Belt drive reduction would be the way to go for a high RPM electric motor. A good design belt drive will only lose about 2-3% of the available power - and a belt drive is light, compared to a gearbox.

A high RPM electric motor can get to 90% efficiency, even the best IC engine is only around 30% efficient. So the power/fuel energy losses of an IC engine need to be taken into account, when you're comparing electric power.

 

Edited July 23, 2022 by onetrack

[RFguy]

something that might look like a big wide supercharger toothed belt ?