Cessna electric
 

1st April ?

a good 1st or april joke need to be just about plausible... make it too ridiculous and you dont fool anyone....

Would that be the 'stretched' 209, 'S' Model, or the standard 11 seat version with the dual thronomisters I wonder....???

Cheeerrrsss….

Or this one just published.

http://sendy.pipistrel-usa.com/uploads/1548916414.jpg

For Immediate Release - April 1st 2019

Pipistrel ALPHA Electro completes 24 hour flight on a single charge!

The Pipistrel ALPHA Electro aircraft has successfully smashed the world endurance record for electric aircraft by completing it's first 24-hour flight on a single charge!

http://sendy.pipistrel-usa.com/uploads/1554103852.jpg

Pipistrel engineers have recently tested different fuel cells and generator units to supplement the ALPHA Electro's current 1-hour range.

Hugh improvements in electrical generation have unfolded with the recent (2016) re-discovery of Kryptonite in Northern Siberia and under the stepped Pyramid in Egypt.

Kryptonite in its purest form is just amazing, a true MARVEL producing almost unlimited amounts of perfect DC energy, ideal for powering an electric aircraft noted a leading Pipistrel engineer, Prof D.C. Currant.

Prof Currant explains, that less than 1 teaspoon of kryptonite mixed with a catalyst of egg whites and Coke Zero can product almost unlimited energy with the only bye product being a bad tasting, dark brown, scrambled egg type mix that can be fed to animals (and men) to keep them warm in winter.

Guinness book of world record officials were in attendance for this world first event and described this as a 'giant leap for mankind' moment!

More information will follow....

Nah Mr C....Tooo much sugar in dat one dere boy...….Hey..???

p.s. Hey Bloke...Gotta dollar for de bus..??

Cheerssss...

What's happened Griffo, Dick's redundo run out?! :eek:

I saw that, but struggle with it. The DHC2 has an empty weight of 3,000lbs and a max all-up of 5,100lbs, leaving a useful load of 2,100lbs (call it 960kg). To this we could add the difference between their electric motor and the weight of the stock radial (say 180kg) giving a useful load of 1,140kg.

Assume to do anything at all beaver-like you'd want it to carry a pilot and five passengers - allowing 90Kg per person that's 540kgs (assume these are day-trips so no baggage apart from the odd fishing rod). That leaves just 600kgs for the battery which (at their claimed 200w/kg energy density) would be a 120kWh battery (ignoring the extra structure needed to sling this 600kg battery under the floor when the fuel tanks usually reside).

Cruise power settings for the DHC2 are 240bhp (53%) or 300bhp (66%), which become 180kW and 224kW in new money respectively. Even ignoring the higher power settings for take-off and climb that gives us a maximum no-reserves duration of 40mins at 53% or just 32mins at 66%. And of course this is with the aeroplane remaining at max AUW for the whole flight (no fuel-burn). Is an aeroplane with less than 40 minute no-reserves max endurance, after which it needs a few hours to recharge, actually useful for anything? What am I missing?

I suppose you could swap the batteries rather than recharge, but these are floatplanes, and removing/refitting a 600kg load up between the floats isn't a typical bit of dockside maintenance AFAICS!

Then remembering that these are not new-builds, but are conversions of ageing aircraft. Most oaircraft of their age are significantly heavier than the book empty weight due to mods, repairs, anti-det husbandry etc (all the more so for seaplanes). Are they looking to grow the max all-up weight?

PDR

Electric Skydive Ops
 

Electric powerplant for skydive ops might be feasible. You could have a few spare quick exchange batteries ready to go after say 2 sorties of 0.3 - 0.4. You can come down near vertical with the prop charging the batteries. Also climbing in the flight levels would not be a problem as the climb rate would be near linear all the way up as there is no loss of power, only slight loss of wing lift efficiency as you climb. Would be the perfect jumpship to convert a Caravan if the batteries aren't too heavy. Just a crazy thought!

Most Beaver flights at Harbour Air are 15-30 minutes long.

Maybe Harbour Air could obtain a waiver for the 30 minutes reserve requirement down to 20 min like helicopters, especially considering that the hydroplane in this case is always over the water and can land at any time anywhere. So then 40 minutes no-reserves would work for many of their Beaver routes.

Recharge time should be less than an hour if the reserve has not been used (example: Tesla Model 3 is only 30 minutes charge time from 20% to 80% on a Supercharger, and Porsche Taycan claims twice as fast).

The fast charge period is to an absolute point, not a relative one. It isn't that it takes 30% to put in 60% of the charge (to use the Tesla 3 example) - it's that you can charge at a higher rate UNTIL you get to 80%* charge and after that you have to drop down to the standard charge rate (which is very slow for that part of the charge anyway). So using fast-charging you can only ever get to 80% charge, That means that the 40 mins at economy cruise becomes only 32 minutes, and even with only a 20 minute reserve that gives 12 minute flights.

And even THAT is over-stating it because we've assumed the whole flight is at economy cruise - no take-off or climb, and of course no taxiing. Is that useful?

PDR

* Most academic sources suggest that this is actually 60% rather than 80% unless you are happy to accept a reduced battery life

Good point on the 80% to 100% charge. The last 10% can take another hour. So let's say charge to 95% in an hour instead of 80% in 30 minutes.

Real life data (for example from this heavy fleet user https://www.tesloop.com/blog/2018/8/...s-in-two-years) who charges typically to 95% and shows only 13% battery degradation after 300000 miles and, even more importantly, apparently showing no further degradation. And we are talking here about 5 year old battery technology, not the latest and greatest.

I am not sure why there is such a widespread negative misconception on reduced battery life and long charging time, I keep reading comments like yours but the reality is very different. I don't know, maybe this is coming from the public perception from cellphone batteries which are unfortunately incorporating programmed obsolescence.

We can't just say that because it can't happen - the last 20% (or more, depending on which sources you choose) is voltage-limited and so simply can't use high current. During this phase of the charge the current tapers off and the rate of charge drops accordingly. You can only "fast charge" for the part of the charge where the higher voltages needed to achieve the higher charge rate won't damage the cells. Fast charging is also very inefficient - you have to put more energy into the cell to increase the charging current, but you still get the same energy out. The snake-oilers of the Electric Vehicle Taliban never seem to mention this aspect.

Automotive experience doesn't really read-across to aviation. Automotive cruise power demands are very small compared to the peak capability, so the batteries have an easy life. As the numbers in my previous posts show, the aviation power demand is much higher, and it's constant. This would work the cells much harder.

Twaddle. My "conception" of battery degradation is based on properly conducted, peer-reviewed engineering studies. Whilst I wouldn't argue that Apple artificially mess with apparent battery life for commercial gain (because they are crooks - go figure) there are other phone manufacturers, and laptops, and power tools, and invalid carriages etc etc etc all of which show this degradation. I have removed the seemingly degraded battery from a cell phone and measured its capacity (both as-removed and after extensive battery conditioning) and personally confirmed that it bot only has less than 60% of its initial capacity, but it also suffers higher impedance (so its terminal voltage drops more under load).

But none of this is relevant to this discussion - I'm just using the data as provided by the project and asking if this really is a viable electric aeroplane.

PDR

The 209 would have to be the ideal platform - I think this will definitely be a goer, especially if it can be retrofitted to existing 209s.

Well, it does. Here is a charge from 50% (the 20 minutes VFR reserve) to 100% in less than an hour (53 minutes mark to 1h48min mark) :
You can believe what you want but this is reality today. The aircraft batteries I am working with on new designs are on par with this and they get better each year.