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-   -   Electric Islander (https://www.pprune.org/rumours-news/614470-electric-islander.html)

pzu 17th Oct 2018 20:46

Electric Islander
 

Herod 17th Oct 2018 21:22

It makes sense to introduce an electric aircraft on the routes around the Orkneys. A big difference between the short hops with a small aircraft and trying a 737 size on longer routes. My guess is it will work.

Chris Scott 17th Oct 2018 22:09

So a two-minute sector (or perhaps a couple) followed by how long a recharging period?

PS: Is this thread restricted to septuagenarians? :eek:

n5296s 17th Oct 2018 22:32

I don't understand how this will work. I thought the Islander was powered by the noise the engines make?

(And no, not quite there yet myself, a few years to go).

treadigraph 17th Oct 2018 23:34


Originally Posted by Herod (Post 10285757)
It makes sense to introduce an electric aircraft on the routes around the Orkneys. A big difference between the short hops with a small aircraft and trying a 737 size on longer routes. My guess is it will work.

We won't charge you if you're wrong...😊

ion_berkley 18th Oct 2018 05:39


Originally Posted by Chris Scott (Post 10285787)
So a two-minute sector (or perhaps a couple) followed by how long a recharging period?

PS: Is this thread restricted to septuagenarians? :eek:

Serious back of the envelope calculation here with a little real world data thrown in:

Islander with 2x 300HP engines = approx 400kW peak power output

Lets assume that the whole 2 min sector is flown at full power to be nice and pessimistic...so 13.3kWh per sector.

Now the complete battery assembly for the Tesla Model3 is pretty representative of the bleeding edge of EV battery technology and it comes in at 168Wh/Kg.
The total mass of the ~75kWh battery pack in a Model3 is approx 470 Kg. Empirically I can tell you that my Model3 charges from say 20% to 80% in about 40 minutes from a DC fast charger.

That passes the smell test for me, it seems very practical for this particularly odd air route.

pattern_is_full 18th Oct 2018 05:53

Yes, the Islander is a pretty flexible little test-bed. There have been ducted-fan, turboprop and 3-engine mods. And minimal systems power-&-complexity overhead required: no pressurization, retractable gear, spoilers, or such.

msbbarratt 18th Oct 2018 06:35


Originally Posted by n5296s (Post 10285809)
I don't understand how this will work. I thought the Islander was powered by the noise the engines make?

(And no, not quite there yet myself, a few years to go).

The noise doesn't come from the engines, their cores are far too small to make that din.

msbbarratt 18th Oct 2018 06:49


Originally Posted by ion_berkley (Post 10285974)
Serious back of the envelope calculation here with a little real world data thrown in:

Islander with 2x 300HP engines = approx 400kW peak power output

Lets assume that the whole 2 min sector is flown at full power to be nice and pessimistic...so 13.3kWh per sector.

Now the complete battery assembly for the Tesla Model3 is pretty representative of the bleeding edge of EV battery technology and it comes in at 168Wh/Kg.
The total mass of the ~75kWh battery pack in a Model3 is approx 470 Kg. Empirically I can tell you that my Model3 charges from say 20% to 80% in about 40 minutes from a DC fast charger.

That passes the smell test for me, it seems very practical for this particularly odd air route.

There are some downsides. The battery is heavier than the equivalent fuel tank. The power cables are heavier than the equivalent fuel lines. The motors are heavier than the equivalent gas turbines, and can't sustain max power for as long either (efficiency in a motor conflicts with cooling it with air). The batteries don't get lighter as they discharge. Charging times are longer than refueling times (but maybe irrelevant given other operational factors).

A lot of these downsides go away or become irrelevant if you consider the electricity to be free (solar, wind, etc). One way or another we seem to be heading kinda in that direction, but it's a long way from free still.

Espada III 18th Oct 2018 07:32

Charging also available from wing and fuselage covering of solar cells. This would have a modest but not negligible benefit on range and charging times.

Capt Fathom 18th Oct 2018 07:41


I thought the Islander was powered by the noise the engines make?
Electric Engines!
​​​​​​​Who would have thought the day would come when an Islander could sneak up on you!

krismiler 18th Oct 2018 08:00

The 300hp version had fuel injection, there was also a 265hp carburettor varient.

​​​​​​The route could be a proving ground for trying out the new technology which could find its way into simple single engine types.

Obviously at the moment it's not a viable replacement for piston engines though.

scifi 18th Oct 2018 10:32

Just one question, how would you fly it out to the Islands from the Mainland, if you require 30 minutes reserve capacity..?

edit... Would their nearest engineering base be Aberdeen, to do the initial installation..?

EDLB 18th Oct 2018 11:31

With 30min VFR or 45min IFR reserve it will become an interesting calculation. Possible, Yes but economic?

scifi 18th Oct 2018 13:02

Just another snag.... How many airfields have the right PLUG...?

Pilot DAR 18th Oct 2018 13:37

I was hired to investigate the design and design compliance of a proposed STC modification of a 172 from Lycoming engine to electric motor. Though achievable, the major commercial obstacle was the loss of use of the aircraft while the batteries were recharged - fly it for 45 minutes, and it then sits for many hours recharging. Not good utility, though it seems like this operation has a better than normal opportunity.

For commercial operation, the modification will have to be STC approved (to maintain a C of A). A challenge is that the present basis of certification of the aircraft (and for STC) contains a lot of design standards which would exclude electric motors as powerplants. This should and will change, though a lot of regulatory changes will be needed, and those don't happen quickly.

Electric planes will become practical for some roles, but in the mean time, some battery advancement is still needed. We'll get there on day, and everyone who is trying, is helping.

Chris Scott 18th Oct 2018 13:43


Originally Posted by msbbarratt (Post 10285992)
The noise doesn't come from the engines, their cores are far too small to make that din.

Yes. Unless they employed very clever technology, the props on the electric one would be nearly as noisy. Would they be constant-speed and fully-feathering, or would either of those features be unnecessary?

Unless the aircraft could continue to do the leg to Kirkwall, which seems unlikely with current battery technology, Loganair must be contemplating creating records for lowest average aircraft utilisation per day.

"Hello Madam, welcome to Papa Westray. I hope you enjoyed your noisy flight from Kirkwall. If you wish to continue your journey, please gather your personal items together and accompany me to our quiet, environmentally-friendly, Whispering Dwarf aircraft for the short hop to Westray...." :rolleyes:

DaveReidUK 18th Oct 2018 14:10


Originally Posted by Pilot DAR (Post 10286262)
Though achievable, the major commercial obstacle was the loss of use of the aircraft while the batteries were recharged - fly it for 45 minutes, and it then sits for many hours recharging.

One way around that would be a quick-change battery module so that they don't have to be recharged in situ.

krismiler 18th Oct 2018 14:17

Possibly some energy could be returned to the batteries by windmilling propellors on the descent in the same way electric vehicles can recharge their batteries by using the motor as a brake.

Electric cars can recharge to around 80% very quickly, it's the last few percent which takes time to trickle in.

Gargleblaster 18th Oct 2018 14:22

Regarding this type, this is one of the funniest posts I've read in here: https://www.pprune.org/tech-log/4363...ml#post6118466


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