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  • Electric Flying

    Electric vs IC has always been a hot debate in the world of RC flying, where I've been an enthusiast for a good decade. Now, slowly, we are finally seeing E power gaining favour in the motor industry. IMO, IC is doomed in the long run. It's gonig to take a lot of work and almost a revolution for oil to lose it's hold on the economy, but it will happen eventually.

    What I'd love to see and, arguably it has started already, is E power in aviation. Pipestrel ( have a lovely looking e powered machine, which despite being in its infancy, appears to have a lot of benefits and potential. The Pipestrel Alpha Electric, laiden with its batteries and a pilot of ~170lb, is 3KG over the microlight weight limit of 450KG, and is a hair over the flaps up stall speed at 43kts. That's getting on for microlight class, and if the UK does in fact adopt the 600KG limit seen elsewhere, we could be in for some very interesting changes.

    Do you forsee e power entering the microlight world in the near future? I can image initial expenses being a little higher, but imagine flying an hour or more on a full charge that cost only 5 instead of a 40 of fuel? Those savings are already happening for me with my car. Whilst I'm paying more overall for my BMW 530e compared to the 10 year old Skoda I had prior that, I'm saving a good 50-60% in fuel each month. Providing I charge ever night, at the cost of about 1.10, I can do my weekly work commute on ~6 a week, as opposed to ~30 in petrol. Do you think we'll see similar tech in microlight flying within say 5 years?
    Last edited by Harry Marshall; 9th January 2019, 13:03.

  • #2
    Electric power has much to recommend it over IC, but it is not a direct replacement in all applications. Where power and endurance are required within a strict weight limit, electric power will never match IC.
    I use the word 'never' with some confidence. While improvements in battery technology over the past two decades have prompted some (including much of the media) to believe that we will soon have batteries to match the energy density of petrol. The truth is that Lithium has the best charge / weight ratio of the elements in the periodic table and this gives us batteries with approx 1% the energy density of petrol. Advances are possible in reducing the weight of the battery package, but this not going to make that much difference.
    Batteries also weigh the same when empty as they do when full, so there is no flexibility to take off with two lardy occupants and enough charge for a couple of circuits.
    Fuel cells offer some benefits over batteries, but then we are back to consuming a fuel. The specific type of fuel is another argument entirely.
    There are also significant issues with widespread adoption of electric vehicles, among them are the energy supply infrastructure (compare the daily energy use of your car with that of your home...), replacement of tax revenue currently levied on fuels and the availability of some of the materials required for high power density electrical systems.
    I am not opposed to electric power. There are many applications in which it is the most suitable of the available solutions. Heavier than air aviation is not one of them.
    Pete T.

    "A closed mouth gathers no feet".


    • #3
      There was an interesting presentation and subsequent discussion on this topic at last year's SSDR rally. There's a bit of a discussion [here]

      One of my concerns in the economics is battery life and replacement cost That, I suppose, is the equivalent of counting engine overhaul and replacement costs within the total flying expense.

      Goo dto discuss though.
      The pilot formerly posting as MadamBreakneck
      R examiner and TST pilot.
      and now a Tai Chi instructor


      • #4
        Power to weight ratio. The only thing that matters if you want a viable Flying machine. Batteries don't give it. Fossil fuels do. Many times over. So No. The Boss's Tesla busted a tyre. Two of the staff were sent from Poole to London to replace the 360 tyre which cannot be repaired No spare. My despised Up! did the same. Two minute drive to tyre shop and 14. Green? Don't think so.


        • #5
          Originally posted by tomshep View Post
          Power to weight ratio. The only thing that matters if you want a viable Flying machine. Batteries don't give it. Fossil fuels do. Many times over. So No. The Boss's Tesla busted a tyre. Two of the staff were sent from Poole to London to replace the 360 tyre which cannot be repaired No spare. My despised Up! did the same. Two minute drive to tyre shop and 14. Green? Don't think so.
          Many performance cars, be it IC, electric, or otherwise do not carry full size spares or even any spare. You wouldn't put a space saver space on a Tesla or petrol Porsche and, personally, I would not risk a tyre weld or other repair on a performance car. Weight saving by not carrying a spare wheel is done for performance, not necessarily because the E car is heavier. Having said that, my 530e is heavier than the petrol equivalent and I have a shallower boot because of the batteries. I guess it depends on what you're doing. Even now, I reckon an electric microlight/LA would be brilliant for circuit training. For me, driving to work and back all week on 6 of electricity is great. Yes, I'm pootling about on 90bhp, not the full 260bhp, but 99% of the work commute is start stop in traffic. Arguably, I don't see the petrol savings compared to my previous 2L petrol Octavia VRS, as the car overall costs me ~100 pm more. However, I made that decision knowing that that extra 100 was upgrading me from a 10 year old, 80k mile skoda to a very fancy new BMW. No brainer for me, especially when it's only a 2 year lease; a nice treat for a couple of years.


          • #6
            It will be interesting to watch developements, both of Adrian Jones's electic Shadow project and the possiblities of the Pipistel. I hope for an undate on the Shadow project at the SSDR rally (please) and it is a sure bet that Deepak at London Airsports, already training with a Pipistrel, will have his eye on that ball.

            It'll be interesting, but I don't expect results for quite sometime, meantime back to the trusty 503


            • #7
              i am really looking forward to seeing electric vehicles and am excited by the prospect of an electric flexwing
              (to me the engineering is straightforward the fuel tank is replaced by batteries designed to fit in the available space, and engine swapped out for the electric motor – the blocker is the wait for the technology to be viable)

              However there are some significant issues that i predict need overcoming to maintain the “pilots experience” (ie what we enjoy about and our purpose for flying) that have not already been mentioned

              Number 1
              charging aircraft at the home airfield/hanger.
              Some at my home airfield choose to have trickle chargers fitted, some in other hangers have small heaters, either way there is a handful of extension cables trailing around the hanger to provide power to aircraft.

              fast forward to the day of all electric/majority electric engine GA/Microlight aircraft and we'll see a hanger looking like an upturned pan of spaghetti of extension leads as power is routed to each aircraft - will hangerage prices increase as the service provided is not just a roof over my aircraft but power for my electric engine?
              There will certainly be an increased electric bill for the farmer with 20 aircraft all drawing a charge to fill up their batteries which they won’t absorb – ok so any hangerage increase is offset by the end to filling up Jerry cans on the way to the airfield but there needs to be some thought on the logistics of getting 20 aircraft all charged through the double socket in the corner of the hanger/barn.
              Could we expect some kind of legislation around mass charging of vehicles?
              Cars and aircraft can sit happily will 40 litres of fuel in their tanks and not cause an issue.
              Batteries however are known to be unstable. We can all find stories of a mobile phone, tablet or vaping device which has got warm, burnt, caught fire or exploded while on charge – something the technology needs to address.

              Number 2
              (the following is assuming the capacity/duration of an electric engine is the same 3-4 hours flight time which has been mentioned is unlikely)

              flying out - although the vast majority of my flights are "local" flying friends over the local sites, towns and of course their house, every so often i do “fly out” to a different airfield for a tea and cake or even lunch. Of these flights, many are close enough I don't need to fill up with fuel having an hours journey in each direction so within my fuel tank’s capacity
              but if i went further afield, and I know many pilots do on a regular basis, say a 90 minute journey or more, how do I get home with a sufficient safety margin on my reserve battery power?
              Airfields will need to change from providing Mogas, 110 LL, Avgas or other to plug and sockets but it won’t just end there.

              Filling up a car, lorry or aircraft takes ~10 minutes and is thus convenient. Stopping at a Service Station on the M6 for a wee stop and fuel fill up is not out the ordinary, nor will it be for a pilot on a long cross country hopping between airfields filling up as they go.
              Battery’s do not recharge from empty to full, or even offer a 50% power increase in ten minutes, I don’t know enough about the technology, but I would hazard 30 minutes is not enough and minimum charge times to provide something useful (ie a boost to battery charge by a third or half) and at a guess would suggest the minimum useful charge time would be in the region of an hour. (it takes my phone ~80 minutes to “fast charge” from flat to full – is a higher capacity battery likely to have the same or longer charge times?)

              Personally an hour’s wait (assuming it is only that) won’t be an issue, if I stop even if it just for a tea and cake I can expect to be on the ground for an hour when including the sigining in, landing fee, wee stop and simply watching the world go by but
              > is that hour sufficient time to offer an adequate charge?
              > will airfields (not known to be rolling in money to spend) be rushing to put in infrastructure for electric charging? (we see more Motorway service stations and even car parks in town (I have even seen this in Ikea) providing electric car charging points, but will small airfields be happy or have the funds to invest in several charging stations?)
              > how can we expect to be charged? Electric car drivers indicate they can charge a car overnight for 1.10 (see Harry above) – if that is a full charge taking say a 6-8 hours duration how will that break down for a hour’s charge?
              The maths suggests 15p for an hour’s charge (1.10/8hours = 13.8p, /6hours = 18.3p) but if an airfield charged the “full charge/8 hour rate” of 1.10 making 1 “profit” does that offer a sufficient money maker?
              I don’t know how much an airfield makes on every litre of fuel, but I would guess from a fill up of 20, 40 or 50 litres of fuel they make more than 1(!) – and income from fuel helps keep that airfield alive.

              Now these numbers are pocket money figures for children, the difference in flying costs by 1 won’t upset a pilot (I cringe at paying 1.40-1.60 when filling up with 100LL knowing its 20p/litre more than the Mogas I put in but needs must and is part of the adventure) but if it isn’t 1.10 to use an airfield charge point, but the fee for use is 5, 10, or even 20 (still less than fuel I admit) will this be a draw to visit while making sufficient money to pay for the charge points? Could we expect the expense to be higher to cover the cost of the infrastructure and its installation? Or simply to recover the lost income of providing fuel?

              This is for an example when visiting an airfield with significant infrastructure, the obvious local examples for me being Popham, Wellesbourne, or Compton Abbas. What about those occasions when we choose to “fly out” to a farm strip which can only boast as part of its infrastructure hot and cold running taps in the toilet and a kettle?

              On one occasion, I strapped in a jerry can in the passenger seat and prior to the return trip emptied the can into the fuel tank due to the limited refuelling options at my destination airfield.
              Will batteries be portable enough to strap into a passenger seat? And then also exchangeable so they can be swapped? Due to the simplicity of our machines I would suggested “yes” as it is difficult for anything in a microlight to be out of reach of a spanner of screwdriver, even the more challenging areas most can be reached with 10 minutes disassembly.
              But at what cost is that second battery?
              Ok in this world of electric vehicles the cost of batteries is likely to reduce, however will pilots choose to purchase a second battery knowing this will be in place of a passenger? (98% of my flights are with a passenger, I much prefer the company and sharing my passion with friends) More justifiable for the long distance or solo pilot but for me, I won’t be rushing to purchase a second battery on the off-chance I want to go further and do so on my own…

              Perhaps my ignorance in the technology is showing through and I have over thought a problem that won’t exist. Perhaps a three pin plug on a 25m extension lead is suitable to charge an aircraft from, solutions will be found ot spaghetti leads covering hanger floors and line up at an airfield and with improvements in the technology we can expect charge times to reduce to an hour or less, but I certainly feel the technology has a long way to come before it becomes a viable option.

              As a marker, when the haulage companies (and I mean the Eddie Stobart’s of the world) start transitioning to electric that will be the same time it becomes viable for the world of GA/private aviation.
              A personal car can be flexible enough to charge it overnight at home and on average has a journey distance less than 60 miles – ie the charge/capacity is greater than the average a single journey.*

              But the same isn’t true for lorries, they need the capacity to travelling 100s of miles per journey with a convenient method to refuel (ie quick) as they are in constant use. Ok so GA aircraft are not in constant use, but when we do get that weather window and we go flying we want the same endurance of a long distance lorry with the same reliability and ease of use.

              *many of the complaints from the general public about electric cars is the limited range – manufacturers counter this argument indicating the average commute is less than 20miles, and other journeys less than 60miles. With the ability to “refuel” at home it becomes more convenient offsetting the need to increase its frequency.


              • #8
                It is necessary to appreciate the scale of the infrastructure requirement associated with electric vehicles.
                A reasonably efficient car on a typical daily commute will use something like 20kw for 1 hour = 20kwh.
                A microlight uses something like 30kw, so a 1 hour flight uses 30kwh.
                A standard 13 amp socket can charge a battery at 3kw, taking 6 hours 40 minutes to recharge your car, or 10 hours to recharge your electric microlight.
                Fast charging stations can do it quicker, but need more power. The Tesla supercharger can charge at up to 120kw. If this were to be driven from the 240V mains supply, it would draw 500amps.
                The main breaker in the average house is typically 60amps or 100amps.
                The average UK home uses less than 10kwh per day.
                The UK electricity infrastructure does not have much spare capacity - live usage can be seen here
                Pete T.

                "A closed mouth gathers no feet".


                • #9
                  500Amps is a lot of trouble if it shorts out. It would kill instantly if you were unfortunate enough to get too close as well. Now let's just get this in perspective. The world's largest nuclear power station has the three biggest reactors in it. To electrify the UK road vehicle fleet would only require six of these power stations to be built.
                  This will obviously go through on the nod and money will be no problem.
                  Environmentalists will cheer with delight.


                  • #10
                    that perfectly explains my concerns and fills in the knowledge gap.

                    I could see a "first attempt" charging at say Popham of several drum reel extension leads stretching out across the lawn to aircraft. A system much like at a caravan site where users bring their cables while the land owner has a box to plug into.
                    However if these plugs can only provide 3kwh/take an hour to charge then there needs to be some significant investment to allow for faster charging or a significant change in how pilots operate when flying out.
                    but the draw on the system would be huge.
                    If the average home uses less than 10kwh/day airfields must be a tiny fraction of this – considering a “typical farm strip” what draw must there be from the lighting the portakabin “Clubhouse”, a fridge to keep the milk cold, a kettle with perhaps a microwave> the increase in the electricity consumption to allow for electric charge would be monumental just to charge a single aircraft let alone a hanger of a dozen or so.


                    • #11
                      Maybe the 'typical farmstrip' could install a diesel generator for charging aircraft

                      The pilot formerly posting as MadamBreakneck
                      R examiner and TST pilot.
                      and now a Tai Chi instructor


                      • #12
                        Guys, I'm not an expert on the subject but we have to remember this is in its infancy. I don't doubt we have, or are very near to having, the tech. A lot of the stumbling blocks will be human greed; how can it be taxed etc.

                        I honestly believe that e power is going to get more popular in the future and it'll catch up. Either way, as an overall society, we need to make changes in the way we make and use energy.


                        • #13
                          E power is hardly in its infancy. At the turn of the last century (c1900) electric cars were dominant, pre-dating and out-selling IC engined cars, holding speed records and in use as taxis.
                          Recent developments in rare earth magnet motors and lithium batteries have yielded significant improvements, but the technology is limited by fundamental laws of physics.
                          If E power is become useful for applications such as microlights, the power will not come from batteries. It may come from a small fusion reactor, or something similarly far off in terms of development.
                          Pete T.

                          "A closed mouth gathers no feet".


                          • #14
                            Originally posted by Joan Walsh View Post
                            Maybe the 'typical farmstrip' could install a diesel generator for charging aircraft

                            I see what you did there...
                            Pete T.

                            "A closed mouth gathers no feet".


                            • #15
                              Actually, I wonder what the cost would be for a solar/wind/battery energy generation and storage set up would be to support a clutch of, say, half a dozen electric SSDR machines with typical hobby usage.

                              Anybody tried to work it out? Would it be big enough to need planning permission?
                              The pilot formerly posting as MadamBreakneck
                              R examiner and TST pilot.
                              and now a Tai Chi instructor