scsirob Posted January 6, 2018 Share Posted January 6, 2018 Copying from what I wrote on the Ransclan forum, where the Pipistrel was mentioned as well, and the 'option' of an electric powered Rans S-21was discussed: --- I don't buy the viability of electric planes in the S-21 class. Let's do a bit of math. The sweetspot for the S-21 when looking at the options mentioned in this thread are engines that produce 120 - 180HP. Let's take 150HP as starting point. Cruise is between 65 and 75%, lets take 70%. So cruise power is 105HP, or 78kW. Now let's take a usable airborne time of 3 hours, which most of us would agree to be the minimum for a usable aircraft. Add 30 minutes reserve, you are looking at 275 kWh worth of power. Not sure what efficiency ratio you can get in electric but let's be optimistic and call it 90%. You'd need 300kWh battery installed. That's three Tesla Model S battery packs with the latest 100kWh batteries. Current weight is 600kg for each battery pack, but technology progresses. Perhaps battery weight can be slashed to acceptable weights. Let's assume it does. Now you've flown 3 hours and your battery is empty. What does the charge cycle look like? You want to return home after visiting the nearby restaurant, eat your $100 hamburger, have a chat with friends. Let's assume you want to return home after 4 hours. You have consumed 3x 78 = 234kW of power. That amount of energy needs to be charged back into the batteries. Again, let's assume 90% efficiency in charging, so in 4 hours you need to inject 260kW. Now take a commercial building 120/208V 3-phase connection. Each phase will need to deliver 180A continuous for 4 hours to make this happen. Mighty big cable, don't even think you can get those kind of current supplies on commercial outlets? You'd need to go 277/480V industrial to make this work. And it still takes 4 hours to 'fill her up'. Now take a look at a residential airport. How many planes fly in and out on a busy day? How many take 10 minutes to fill the tank? These all need 4 hours now. So put them all on a row and supply them with a charger cable. How many chargers would you need? That, times 180A 3-phase. My conclusion: Even if motor/battery dimensions are developed to fit, the issue will be the charging infrastructure. Every airport would need a mid-size nuclear power plant next-door to keep the planes flying. Not an option. The power density of gasoline is very hard to replace. Very slick low-drag aircraft may get an hour or so of airtime. Our relatively draggy Rans/Murphy/Cub/Cessna type planes will never be a viable option. Happy New Year to you all! Link to comment Share on other sites More sharing options...
bexrbetter Posted January 6, 2018 Share Posted January 6, 2018 Now let's take a usable airborne time of 3 hours, That's three Tesla Model S battery packs with the latest 100kWh batteries. Current weight is 600kg for each battery pack, Pipistrel use a 150kg pack for 1 hour, and here you are suggesting 1800kgs for 3 hours. Of course the extra battery weight, greater wing loading or wing area, consumes more power exponentially, but I reckon just one Tesla battery pack ain't going to be a long way from 3 hours in the right setup, I would suggest 2.5 hours is solid. Link to comment Share on other sites More sharing options...
scsirob Posted January 6, 2018 Share Posted January 6, 2018 Pipistrel use a 150kg pack for 1 hour, and here you are suggesting 1800kgs for 3 hours.Of course the extra battery weight, greater wing loading or wing area, consumes more power exponentially, but I reckon just one Tesla battery pack ain't going to be a long way from 3 hours in the right setup, I would suggest 2.5 hours is solid. I tried to put things in perspective. Pipistrel uses a 50kW motor. At 70% it would be running at around 35kW. Equivalent to a Rotax 503 or 582. You can get away with that with a slick, light plane like the Pipistrel. You can not do that with the equivalent of a Cessna or a Rans S-21. If you want the equivalent of a 150HP engine and 3 hours endurance then you will need 300kW worth of batteries. Tesla's equivalent weighs 1800kg. The 150kg Pipistrel pack has approx the same amount of energy density in kW/kg as the Tesla packs. You'd need roughly the same weight in Pipistrel packs if you want that 300kW of energy. And again, my point wasn't to show that the motor and battery technology can't be developed to fit. Perhaps in a few years all that will be reality. My point is that the charging infrastructure needed to keep a fleet of GA planes in the air is immense, and I don't see it happen. Link to comment Share on other sites More sharing options...
Jay_1984 Posted January 6, 2018 Share Posted January 6, 2018 Found an AOPA article from the US about the Electro. Thought it was a pretty good review of a possible future for training. Pipistrel Alpha Electro: The trainer of the future? - AOPA 1 Link to comment Share on other sites More sharing options...
red750 Posted January 6, 2018 Author Share Posted January 6, 2018 Back to the slide in, slide out battery exchange, a la the gas bottle exchange at Bunnings.. 2 Link to comment Share on other sites More sharing options...
kgwilson Posted January 6, 2018 Share Posted January 6, 2018 Back to the slide in, slide out battery exchange, a la the gas bottle exchange at Bunnings.. And as batteries continue to get cheaper, this is the perfect solution for a training scenario. The technology is here and its advancement and growth is exponential. The only real current problem is endurance & my bet is that will be overcome within a very few years. 1 Link to comment Share on other sites More sharing options...
slb Posted January 6, 2018 Share Posted January 6, 2018 Try this for size, not sure of pricing Aeros - Trikes & Wings for trike.Believe the first one has arrived in Oz. Make the wing into solar panels and it would really make it cheap flying! 1 Link to comment Share on other sites More sharing options...
w3stie Posted January 7, 2018 Share Posted January 7, 2018 Back to the slide in, slide out battery exchange, a la the gas bottle exchange at Bunnings.. This is the way they should go with electric cars IMO. Drive into a charging station, robot unclips the old battery pack and inserts the new one while you wait. You never own the battery, like the gas bottles the cost is taken up by the recharge. 3 1 Link to comment Share on other sites More sharing options...
red750 Posted January 7, 2018 Author Share Posted January 7, 2018 Should take no longer than changing the battery in your gas guzzler. Link to comment Share on other sites More sharing options...
BlurE Posted January 7, 2018 Share Posted January 7, 2018 I think energy density means practical electric aircraft are still some time off although we have come a long long way from lead acid batteries. However if you were going to play with electric technology the pipistrel alpha is a great place to start. With a rather slippery 17:1 glide ratio the 80hp rotax version has stunning climb performance and requires only moderate power in cruise. Honestly without brakes (in my few hours) I found it a bugger to get down. 2 Link to comment Share on other sites More sharing options...
w3stie Posted January 7, 2018 Share Posted January 7, 2018 I think we’ll see hybrid aircraft before full electric. There are some interesting developments Hybrid Engines in Aviation 1 Link to comment Share on other sites More sharing options...
skippydiesel Posted January 7, 2018 Share Posted January 7, 2018 I never cease to be amazed at the exorbitant cost of anything supplied from Europe. Their pricing is always uncompetitive to me.I strongly suspect we're being reamed senseless to cover their massive taxes that supports the monstrous EU bureaucracy, their socialist lifestyles, and their huge pensions and perks. Me thinks you are a casualty of propaganda, or fanatical conservatism, or just jealous. What's stopping Australia from producing advanced aircraft of this ilk............?????? 1 Link to comment Share on other sites More sharing options...
skippydiesel Posted January 7, 2018 Share Posted January 7, 2018 A friend of mine recently bought a new long wing CTLS or whatever they are called with a 100hp Rotax. Set up in LR cruise it can do almost 8 hrs around 1000 mn under fav conditions, nothing out there today or in the forseable future can come anywhere near those numbers using EP.I hope they do but for now expect Otto's design to be around for a loooong time yet! There are plenty of very able competitors (better) to the CT range - they just dont have the marketing $$ to bluff you into believing their hyp. Link to comment Share on other sites More sharing options...
Downunder Posted January 7, 2018 Share Posted January 7, 2018 Back to the slide in, slide out battery exchange, a la the gas bottle exchange at Bunnings.. Spot on Red!. Also, if "one up", what about a spare set of batteries or two onboard? As this aircraft is for Rottnest trips, the best setup would be to exchange batts at Rotto? I don't think electric motors can be directly compared to IC engines in power delivery, ie 70% power. No doubt motors have different power curves and efficiency rpm. They have special props and related IFA systems to make the most of this power. I think indirect comparisons with stated aircraft capabilities are better than going head to head, motor vs engine. I read one report from an electric powered aircraft pilot owner who said he got far more use/power from his aircraft in reality than calculated as a conversion from IC. You can glide on descent with zero power used and even recharge if power regeneration is capable. Something you cannot allow for in an engine. I think ultimately, electric aircraft need to be built from the ground up as electric. I think the current aircraft are adapted from IC powered airframes which is not ideal but ok for testing and marketing. The real revolution will come fro 100% electric designed and powered craft. 1 Link to comment Share on other sites More sharing options...
danny_galaga Posted January 7, 2018 Share Posted January 7, 2018 It wasn't so very long ago (less than 20 yrs), that a desktop computer cost $2000, took up a huge amount of room, struggled to render complex graphics, slowed up when processing multiple tasks and streaming images.Today, my $200 smartphone fits in my pocket, and can do more than that 20 yr old computer at 5 times the speed - all on the power of a battery that only takes up less than half my palm in size. Battery technology is being improved at a quantum rate, just as computer chip technology has improved at astronomical rates in the last 20 years. There are hundreds of universities, companies and researchers all racing to reach a new major milestone in battery development, as regards faster charging, higher energy density, and lighter battery weight. There will be battery power breakthroughs in the next 5 to 10 years that will make them very competitive. Automotive manufacturers will be the leaders in development as electric power gradually overhauls IC power in urban vehicles. Aircraft electric power does provide a major obstacle in the need to keep weight down. However, with the average IC engine in light aircraft weighing around 90-120kgs, this gives electric power a sporting chance to compete. Definitely see improvements in batteries more so than processors. They’ve hit a bit of a plateau in terms of speed Link to comment Share on other sites More sharing options...
SDQDI Posted January 7, 2018 Share Posted January 7, 2018 Me thinks you are a casualty of propaganda, or fanatical conservatism, or just jealous. What's stopping Australia from producing advanced aircraft of this ilk............?????? Sorry for the funny Skippy. I guess it was my pessimistic side laughing at the thought of anything being manufactured here. Link to comment Share on other sites More sharing options...
Gravity Posted January 7, 2018 Share Posted January 7, 2018 There are plenty of very able competitors (better) to the CT range - they just dont have the marketing $$ to bluff you into believing their hyp. Am not bluffed at all, am old enough to know what's what, near 40 yrs flying from C150 thru to Airbus I ain't a novice! Footnote, 'hype' has an 'e' on the end Link to comment Share on other sites More sharing options...
onetrack Posted January 7, 2018 Share Posted January 7, 2018 Me thinks you are a casualty of propaganda, or fanatical conservatism, or just jealous. What's stopping Australia from producing advanced aircraft of this ilk............?????? There is more than one thing stopping Australia from producing an advanced aircraft. Our lack of risk capital for one. In Europe, which is awash with "old money", throwing a few hundred million into high risk, high-tech projects is only on a par for those investors, with them throwing a bet on the roulette wheel at the local casino. In Australia, there is virtually nothing by way of Govt incentives or grants to develop high-risk, high-tech projects. You do it on your own - but when you produce a winner, the Govt then wants to help you. Just like banks, who take away your umbrella when its raining - but who give it to you when the sun's shining. Oh, by the way, Australian banks are also part of the financing problem. Compare this approach with the likes of the U.S. - where Govts grants for research are available by the hundred, and the U.S. Govt backs sizeable numbers of companies wanting to research and develop high-tech designs. Then there's the complex Australian regulatory and extreme safety culture to overcome before you can build and test-fly your high-tech dream. Then the punters expect your high-tech product to be 1/3rd the cost of the EU import, because it's locally-produced and "can't be any good". As an Australian inventor and builder, you're up against slick EU marketing and promotion - to those same "old-money" Europeans, who are ready and willing in sizeable numbers, to buy a new, local high-tech aviation product for $150-200K - because those kind of $$'s is loose change to them. But they'd rather buy European, because that stuff from the land of Kangaroo is pretty crude and low-tech, isn't it? Not to mention, they are so-o-o far away, when it comes to technical support?? 1 Link to comment Share on other sites More sharing options...
Gravity Posted January 7, 2018 Share Posted January 7, 2018 A There is more than one thing stopping Australia from producing an advanced aircraft. Our lack of risk capital for one.In Europe, which is awash with "old money", throwing a few hundred million into high risk, high-tech projects is only on a par for those investors, with them throwing a bet on the roulette wheel at the local casino. In Australia, there is virtually nothing by way of Govt incentives or grants to develop high-risk, high-tech projects. You do it on your own - but when you produce a winner, the Govt then wants to help you. Just like banks, who take away your umbrella when its raining - but who give it to you when the sun's shining. Oh, by the way, Australian banks are also part of the financing problem. Compare this approach with the likes of the U.S. - where Govts grants for research are available by the hundred, and the U.S. Govt backs sizeable numbers of companies wanting to research and develop high-tech designs. Then there's the complex Australian regulatory and extreme safety culture to overcome before you can build and test-fly your high-tech dream. Then the punters expect your high-tech product to be 1/3rd the cost of the EU import, because it's locally-produced and "can't be any good". As an Australian inventor and builder, you're up against slick EU marketing and promotion - to those same "old-money" Europeans, who are ready and willing in sizeable numbers, to buy a new, local high-tech aviation product for $150-200K - because those kind of $$'s is loose change to them. But they'd rather buy European, because that stuff from the land of Kangaroo is pretty crude and low-tech, isn't it? Not to mention, they are so-o-o far away, when it comes to technical support?? All very true. Australia doesn't have the imagination, we have a complex corrupt Govt system, we have a very unstable workforce, powerful unions, very high wages, low population level for our land mass & a high level of bludgers and wealfare recipients & imports who abuse our kindness. We are a minerals wealthy nation run by a few top end greedy corporate thugs with the politicians in their back pockets, we will never amount to anything on the world stage as we have no manufacturing industry worth anything competitive! 2 Link to comment Share on other sites More sharing options...
bexrbetter Posted January 7, 2018 Share Posted January 7, 2018 I think ultimately, electric aircraft need to be built from the ground up as electric. Correct, and as I've proffered a number of times, I expect to see a few deltas or similar mostly wing craft in the near future. They offer the space for batteries and wing loading that a 'normal' plane can not. Link to comment Share on other sites More sharing options...
onetrack Posted January 7, 2018 Share Posted January 7, 2018 I expect to see a few deltas or similar mostly wing craft in the near future. A lightweight electric Dyke Delta? 1 Link to comment Share on other sites More sharing options...
skippydiesel Posted January 7, 2018 Share Posted January 7, 2018 ."...................., the best setup would be to exchange batts ........... "Agreed. This is a bit of a no brainer as the time taken to change a battery(s) may be similar to refilling a conventionally powered aircraft with hydrocarbons - waiting for the battery to charge using existing technology takes forever. "I don't think electric motors can be directly compared to IC engines in power delivery,. No doubt motors have different power curves and efficiency rpm." Agreed - electric motors have very different power curves to combustion engine, can spin up to jet speeds (probably a better comparison) if need be or rotate at optimum prop efficiency speeds. As with existing engines prop design will be critical. "I think ultimately, electric aircraft need to be built from the ground up as electric". Yes & No - an airframe is an airframe - mission, weight/balance of motor, fuel & payload will dictate most of the design. The airframe cares little for how the power is delivered (jets excepted). Motor shroud/cowlings can take advantage of lower cooling needs and small dimensions for more efficient air flow and or "sexier" look. Link to comment Share on other sites More sharing options...
phonetic Posted January 8, 2018 Share Posted January 8, 2018 40kW motor 30kWh battery total mass of motor and battery 200kgs, there goes my idea of CAO 95.10 home built electric aircraft Link to comment Share on other sites More sharing options...
onetrack Posted January 8, 2018 Share Posted January 8, 2018 The Chinese are perfecting an Aluminium/Graphite Dual-ion battery (AGDIB) for commercial production in the very near future. This AGDIB has 200% better energy density than any current Li-ion, is 50% lighter, and costs 50% less to produce than Li-ion batteries. In addition, it's more environmentally friendly than Li-ion, and is unlikely to see raw material cost spikes - as has happened with Lithium - because Aluminium is cheap and plentiful. It's a big step forward in the EV field, and it's highly likely we will see it in commercial production within a couple of years. https://phys.org/news/2016-10-efficient-dual-ion-battery.html Link to comment Share on other sites More sharing options...
bexrbetter Posted January 8, 2018 Share Posted January 8, 2018 The Chinese are perfecting an Aluminium/Graphite Dual-ion battery (AGDIB) for commercial production in the very near future. Tomorrow I will be meeting with the man who does the lobbying and paperwork for the yearly research grants for the group who holds the patent for it. The research grants are very lucrative, they aren't in any hurry. Link to comment Share on other sites More sharing options...
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