Primarily for general aviation discussion, but other aviation topics are also welcome.
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By Genghis the Engineer
I've flown the 912 engined Pipistrel Alpha when the company put a type course on for BMAA inspectors, it really impressed me as a training aeroplane, but may be a bit of a handful if you're used to heavy handling GA like the C172 or PA28.

40 minutes sounds about right to me for endurance before reserves. (E)26k per battery pack, and a warranted 700 recharge cycle life on them - say double that in reality means that the wet rate will not be trivial. But, let's say 1000hrs per battery set, at (E)26k, only a few euros per flight for the electricity - that's (E)30/hr + aeroplane fixed costs. So around half an SEP doesn't seem unreasonably - just there's a big front-loading cost. Not unlike having an engine fund really.

Personally I think that some form of "differences training" is totally appropriate and necessary between CEP (Centreline Electric Propulsion) and SEP, but don't see why it needs to be any more complex than, say, going from nosewheel to tailwheel, or analogue instruments to EFIS. There are issues however, to do with power management / switching / emergency handling / W&CG that need to be understood and will differ between the two.

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By Sooty25
however much I love the idea, I'm not sure how many airfields will put in a fast charger in the off chance you turn up for a burger, twice a year!

So it'll be your home base for charging and if you want it to do more than 1 flight a day, you need the extra pack and a 1hr charger upgrade. That takes me to E160.5K for a trainer that hasn't got the duration for a cross country.

Oh, the 20kw charger, you'll need a 40amp 3phase supply in your hangar for that little baby!

Even ignoring having to find your engine fund in advance, it doesn't stack up yet, IMO
By cockney steve
Instead of stashing jerry-cans of fuel in the back,, stick in a an "away" airfield, set the genset on the ground, plug-in and start.......clear off for lunch /a brew/a natter and a few hours later you'll be all set to pack it away and go.....
Oh, wait,....... :mrgreen:
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By akg1486
Without the government subsidies, the fanancials probably don't add up. At least not at an hourly rate that's half of what a C172 costs.

I have some interesting stats, though: 60% of our flights since June 2014 are local, i.e. without visiting anywhere else. 45% of those were airborne 40 minutes or shorter. My guess is that at least 75% of those carried max two POB. That means that the Alpha Electric, with its severe limitations in range, could have managed 20% of our flights. (# of flights, not hours flown.)

Electric may bring new pilots, too: tech nerds and green activists. We'll see. It'll be interesting either way.
By mr spog
Pilot magazine recently had an article on electric aircraft with counter rotating props centrally mounted. It was very interesting and listed a number of advantages that I had not even thought of.
For example no engine cooling system, so more efficient cowling. No spiralling airflow over the fuselage making it more streamlined. Plus many more.
Worth a read if you're interested.
Last edited by mr spog on Thu Jan 03, 2019 9:56 pm, edited 1 time in total.
By neilld
Genghis the Engineer wrote:Right now, there is probably nothing that electric aircraft can do better than a good IC aircraft.

But, we're heading into the overlap, and it seems highly likely that within the next 10-20 years there will be roles where electric, and particularly hybrid, aircraft become increasingly useful. In the short term we'll be looking at training aircraft.

A presentation on the topic is here, for those who use facebook, from November's RAeS GA design conference... ... 0830726334


Is there any way non-Facebook users can access this? It has't been published on the RAeS website yet.

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By skydriller
akg1486 wrote:Our club, Aeroklubben i Göteborg, is slated to get an electric Pipistrel sometime 2019. It will be owned by the airport, mostly paid for by taxpayer subsidies, operated by the club and fuelled by a solar farm just adjacent to the field. We'll get one more charging station that will be placed at an airfield around 30 minutes away. We can go there, have a coffee while it charges and then go back. Or we can do local bimbles; the range is some 40 minutes, AIUI.

Is that a 40minute Range or 40minute endurance ? what about the requirement to have a "fuel reserve at destination", or is that conveniently forgotten? Even on a local bimble i was taught i needed to have enough fuel to divert and land elsewhere...

I would agree that the main flight profile of any aeroclub is probably 50% or more local flights of less than 1 hour, but will this aeroplane fulfil this safely or even within current rules as i believe EASA even has something to say about fuel reserves in the regulations for private flights.

Regards, SD..
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By skydriller
To enforce my point, at my aerodrome we have two other small aerodromes around 10-minutes flight time away. i would not take off to do 3-4 circuits with only 40minutes of fuel onboard.
When it comes to flight planning, maybe Im a wimp, but as another example, Several years ago i arrived at Nevers around 5pm to find that their fuel pump had just broken. I calculated I had 45-50mins of fuel left - the closest option was 15 mins flight time but in the middle of nowhere and as it was now almost 5pm there was no guarantee that the guy would be there to fuel me when i arrived...i decided to cancel the onward leg and stayed overnight.

If you screw up the range calculation due unforseen circumstances in a car you coast to the side of the road...aeroplanes dont have that option.

Regards, SD..
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By GrahamB
If the Pipistrel were an EASA type, flights to the next airfield as described in the OP would be illegal by dint of Part NCO..OP.125, which requires a reserve of 30 minutes after landing on a daytime VFR A to B flight.

The UK ANO is less prescriptive, and just requires that the PIC carries sufficient fuel for the intended flight and that a ‘safe margin has been allowed for contingencies’.
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By foxmoth
40 minutes is fine if there is some reserve there, but most batteries deteriorate over time so how long before that 40 minutes becomes 30 then 20?
On a more positive note a freind who is involved with electric aircraft was telling me that battery technology is advancing at the speed computers were 20 years ago, it is early days ATM so who knows where we will be 10 years down the line!
G-BLEW, Rob P liked this
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By Genghis the Engineer
I am pretty certain that the Pipistrel Alpha Electro will give about 40 minutes flying time plus 30 minutes reserves.

The deterioration in service is definitely a big unknown and presumably one reason why Pipistrel are only warranting the battery pack for 700 recharge cycles.

Battery technology is definitely improving, bbut frankly nowhere near as fast as computing technology was for a while. We do need several areas of improvement...

1 Energy density - currently about 1/12th that of fuel. Break even on payload will occur when it's at about a quarter that of fuel.

2 Cost - presently very high, but coming down.

3 Number of recharge cycles before end of safe life. Right now it's in the order of 1000 : we need 2000-4000 to start being cheaper through life than fuel based aircraft.

4 Ability to recycle. An all-electric should have about 1/3rd the carbon footprint of a fuelled aeroplane, but all of the other emissions, particularly from lithium mining are horrendous. At present there is little good technology for recycling lithium batteries at end of life, they are mostly just going into landfill.

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By Grey Beard
akg1486 wrote:One would think that the solution to an emission-free fuel would be an engineered photosynthesis that generates carbohydrates from the carbon dioxide in the air. In essence, something that mimics plants. But I've never heard anything about that. In the meantime, there's plenty of work being done to create (jet) fuel from biological sources such as waste material from the lumber and paper industries.

Check this out: There was an article in the AOPA magazine a few years ago about someone working on this as a source of 'drop in' aviation fuel (sorry, can't find the article).