Are there any Electric aircraft flying in Australia ...yet ?

[boingk]

Good point, but I rekon you'd be fairly safe with minimum 90min operational duration.

 

Worst comes to worse then call and get priority:

 

"Volture 1234 electric ultralight request priority landing on low charge"

 

- boingk

 

 

[fly_tornado]

call a fuel emergency and jump the queue. It's not like they can check your fuel tank.

 

 

[Guest ozzie]

Engine maintenance comes down basically to replacing two bearings. Should get around a thousand hours out of them. No other moving parts.

 

For some reason as someone gets close to getting a reasonable product close to marketable they go quiet. Couple of years ago it was Yuneec with a ppg and several fixed wing single and twin engine concepts. But they seem to have come off the boil. At Airventure there was a e moni, trike and the e gull and spyder gone quiet as well. The lazair needs an injection of funds to complete the design and testing and that would take another twelve months before any sign of production.

 

 

[alf jessup]

Good point, but I rekon you'd be fairly safe with minimum 90min operational duration.Worst comes to worse then call and get priority:

 

"Volture 1234 electric ultralight request priority landing on low charge"

 

- boingk

Another problem I see is short circuts in a variety of instances and meanings.

 

You could always call them and get polarity instructions too.

 

No, on a serious note I would be quite happy and comfortable litterally sitting behind a electric fan if it had the endurance.

 

Alf

 

 

[Marty_d]

What I like about electric is the much greater range of possible configurations. Multiple engines, no fuel lines, switch them off mid-flight when you don't need them. No oddly-shaped cylinder heads sticking out requiring draggy cowls. As soon as photovoltaic paint becomes available, leave it parked outside for cheap refuelling...

 

 

[boingk]

For sure! I'm really thinking it'd be fun, though, to take a vintage design that is designed for a relatively heavy engine up front - like a Pietenpol - and throw a motor and batteries in it. If you budget a good amount (say 10k overall) for the battery and engine package then you'd be laughing.

 

The big thing in shorting is looking after your battery cells and ESC. You want a good safe soft-cut on your speed control and plenty of reserve amperage on the ESC (ie 250A ESC for a max load situation of 200A).

 

I'd say a good safe soft-cut (reduced output from batteries) would be at 3.5v/cell under load. This will give you a static reading of 3.7v/cell and should both prolong battery life and minimise the chances of ever getting a bad cell or overheat situation. Downside is you'd need more battery capacity than say a traditional RC modelling 3.0v/cell cutoff. A soft-cut is designed to get you to a landing zone after you have exhausted your safe minimum charge level (eg below 30% remaining), as opposed to a hard-cut which stops the motor entirely.

 

Cheers - boingk

 

 

[eightyknots]

What I like about electric is the much greater range of possible configurations. ...

Until battery technology improves, avgas or mogas powered planes will continue to have the greater range.

 

 

[Mick]

To date, I have OVER 3000 hours of electric flying time with RC aircraft.

Based on 10 minute flights ( which alot of electric models do not achieve ), that is 5 flights a day, every day for 10 years?????

 

 

[Gforce]

Based on 10 minute flights ( which alot of electric models do not achieve ), that is 5 flights a day, every day for 10 years?????

Yes that would be ( somewhat ) correct ! Been flying electric for 20 years .I fly ALOT but also fly UAVs that have alot of range and airtime. In all fairness, fly electric planes could be called my " other Job " as I do product testing, reviews and UAV work so it quickly adds up.

 

Back to the subject however, one of the best electric conversions I have seen was a Rutan Quickie. Build just for his own use and gets 90 minutes flight time.

 

 

[Gforce]

 

Any recent news you can tell about the Flynano? It's gone awfully quiet for the last nine months or so. I'm aware of the northern winter issue but we only saw a take-off with a conspicuously absent landing (last seen heading for grassland on the edge of the lake).I'm also interested about the configuration, I guess they must have their IP Applications filed by now so can you tell us anything about what they consider to be patentable? To me it would appear to be much the same as other joined wing, closed wing and box wing aircraft some of the concepts of which have been around since the 1920s, some examples pictured below.

 

Also - do you know what has been done to address the inverted stall issues that seem to plague this general design concept? It seems to be insurmountable in the Stratos and the Flynano looks very similar in layout and probable CG position.

 

Gforce Answered:

 

Sorry, I forgot to Answer your question. Development of FlyNano continues. However, one of there biggest issues has been the weather in Finland. Its a very short flying season for aquatic aircraft so any re development work really does not allow for the right testing time. If it was being developed in a sunny, warn country like most of Australia would provide, I believe they would of completed the V2 testing by now. There is a new motor, esc, batteries and improved wing area with the V2 so like you, I'm very keen to see this begin testing. Once, it has proven to be all that it is capable of being with Safety at the top of the list, I will start importing them. Not before.

[bexrbetter]

Im not sure what you mean Alan ? To date, I have OVER 3000 hours of electric flying time with RC aircraft. Never had one issue ! Electric engines are very proven. Have been for over 30 years ! I would MUCH prefer to be flying an electric than an old 337...447...With respect, have you ANY evidence of even 1 in flight failure of an electric engine ?? If so, it would really help with with my research so thanks if you can ? we have not been able to find even one to date...

 

Thanks for your input Alan.

Gforce, I think there's a huge distance between RC aircraft and the mass produced real deal. Your RC power trians are simply not scaleable. I also think that reliability based on budget unlimited examples aren't realistic examples either, not that there's not many of them.

 

The electric car company I work with sometimes, have had multiple failures of controllers, battery cells, terminals etc. and there's no way you would get me into a flying version. They use some pretty good quality stuff too as well turning out 2 or 3 vehicles per week.

 

Engines themselves rarely stop if ever but that's only a small part of it.

 

As for hybrid, well it semed nice 15 years ago but turbo diesels are flying past them now, go compare a VW Polo Diesel with a Toyota Prius, the Polo wins in every way hands down such has been the advances in diesel engines in the last 10 years.

 

PS; Why do all electric planes have to look like sci fi magazine cover pictures?

 

No idea what the reliability fears are all about - so many less moving parts and such simpler operation...

And that's what Mazda used to claim for their Rotary too

 

 

[Gforce]

Thats the thing, Electric motor ARE very scalable. They are also incredible simple when you look at a Brushless motor internals. Alot of us rewind our own motors. t electric power for recreational aviation applications is fairly new, without question Electric aircraft will play a huge part in our hobby. It is coming along in leaps and bounds already and is very exciting.

 

 

[bexrbetter]

Electric motor ARE very scalable.

That's NOT what I said.

 

 

[Gforce]

You said " Your RC power trians are simply not scaleable. "

 

 

[Marty_d]

Whatever the CURRENT problems with electric drive trains (no pun intended), it seems inevitable that they will be overcome in the near future. RC speed controllers etc may not be scalable, but an electric motor is an electric motor whatever the size so I think you're arguing over 2 different things.

 

I'm very excited about full size electric flight. Don't know that I'd fly into a thunderstorm though....

 

 

[Gforce]

No argument, just trying to get some market information really. I obviously agree with you. we are seeing some very well funded companies now look at electric power trains as highly reliable alternatives to IC motors. Having been though an engine failure I am always interested in first and foremost reliability.

 

What we are starting to see if the idea of the " personal plane " come to life now with electric motors and this is very exciting. Sure, flight times are still ( for the most part ) very limiting but If I can go jump in my FlyNano and fly around the lake doing splash and goes for 40 minutes then as a pure flying fun experiences this will be well received.

 

 

[Guernsey]

beI'm very excited about full size electric flight. Don't know that I'd fly into a thunderstorm though....

It would be worth a try though.....battery recharge in two seconds???

 

Alan.

 

 

[boingk]

"If we can pull this off... we're set!"

 

I think its all a very interesting concept but we still need larger motors, higher capacity batteries and better control systems. Current battery technology is good, but it really isn't as good as we need it to be. We're utilising circa 100Wh per kilo lithium batteries... fuel gives us around 12kWh per kilo. Even if we only run an engine that is 30% efficient then we still are much better off running fuel at the moment than running batteries.

 

Scaling it back to my good old Minicab, lets say I got my best documented fuelburn or 12L/hr getting to Temora from Goulburn. Lets say the engine was putting out around 50hp/37kW constant for the flight (75% throttle at 2200rpm). For the 90 minutes I took to fly that distance (~120Nm @ ~80kt) I would have used 18 litres of fuel and expended 155kWh of fuel energy (18L x .72 for kilos and then x 12 for kWh). That figure - 155kWh - would be equalled by a battery putting out around 43kW (85% efficient powertrain running at 37kW output), or around 65kWh for the 90 minute flight.

 

Now if I have done my math right, at cutting-edge hobby scale of 120Wh per kilo you are looking at 520 kilos of batteries to get the same 90 minute flight in the same aircraft. Oh, and they cost $50 or more per kilo initially.

 

Alternatively you could just use 13 kilos (18 litres) of automotive fuel.

 

Electric flight is a pipe dream at the moment for all but the most wealthy, dedicated and ingenuitive of people. My simple (if probably flawed) example shows that fairly clearly. Most experimental aircraft being taken up for flights are relatively slick and extreme designs like the Cri-Cri, and they are being brought down again in 10 minute windows.

 

It is a start, but to be honest that's all it is. A start. Current battery technology just isn't up to the standard we have designed aircraft around - the internal combustion engine. The next wave is most likely what is being dubbed 'Lithium-Air' batteries, and they may provide a bit of a leap forward.

 

- boingk

 

 

[Head in the clouds]

"If we can pull this off... we're set!" I think its all a very interesting concept but we still need larger motors, higher capacity batteries and better control systems. Current battery technology is good, but it really isn't as good as we need it to be. We're utilising circa 100Wh per kilo lithium batteries... fuel gives us around 12kWh per kilo. Even if we only run an engine that is 30% efficient then we still are much better off running fuel at the moment than running batteries.

 

Scaling it back to my good old Minicab, lets say I got my best documented fuelburn or 12L/hr getting to Temora from Goulburn. Lets say the engine was putting out around 50hp/37kW constant for the flight (75% throttle at 2200rpm). For the 90 minutes I took to fly that distance (~120Nm @ ~80kt) I would have used 18 litres of fuel and expended 155kWh of fuel energy (18L x .72 for kilos and then x 12 for kWh). That figure - 155kWh - would be equalled by a battery putting out around 43kW (85% efficient powertrain running at 37kW output), or around 65kWh for the 90 minute flight.

 

Now if I have done my math right, at cutting-edge hobby scale of 120Wh per kilo you are looking at 520 kilos of batteries to get the same 90 minute flight in the same aircraft. Oh, and they cost $50 or more per kilo initially.

 

Alternatively you could just use 13 kilos (18 litres) of automotive fuel.

 

Electric flight is a pipe dream at the moment for all but the most wealthy, dedicated and ingenuitive of people. My simple (if probably flawed) example shows that fairly clearly. Most experimental aircraft being taken up for flights are relatively slick and extreme designs like the Cri-Cri, and they are being brought down again in 10 minute windows.

 

It is a start, but to be honest that's all it is. A start. Current battery technology just isn't up to the standard we have designed aircraft around - the internal combustion engine. The next wave is most likely what is being dubbed 'Lithium-Air' batteries, and they may provide a bit of a leap forward.

 

- boingk

The only practical way to go is series hybrid electric, and it has many potential advantages.

 

Reliability should be up there with turbine engines if not better.

 

The earlier comment about outrunners not being ideal because of the issues of cooling the windings isn't the case if you use liquid cooling, in fact you need to use outrunners in that case so that the windings are wound onto a stationary core which is drilled with water galleries.

 

The batteries need to be heated to get the best out of them (see the Stemme motor glider ...), they actually perform way better at around 70-85C, so you use the heated motor coolant to heat the batteries (and for cabin heat). Fortunately the motor produces most heat when it is working hard and that is also when the batteries need most heating, for once waste energy is a benefit at the right time.

 

Batteries at this stage need to be LiFePO4 (Lithium Iron Phosphate) LiPos are too dangerous as they could catch fire. Lithium-Air batteries won't work in this application because they're not rechargeable.

 

The prop can be optimised for cruise and for a two seat LSA type it might be set up so that it absorbs about 40hp.

 

Approximately 15-20 mins of battery capacity (at 40hp) is all that is required. The 'range extender' engine/alternator (which can be mounted anywhere in the aircraft) needs to be about 50hp.

 

For take-off and with cold electric motor and liquid cooling the motor should be quite capable of being overpowered in excess of 150hp for 2-3 minutes using power from the batteries and the generator together. The only limit on an electric motor's output is it's core and windings' temperature. Using a cruise prop and driving it at higher than optimal horsepower has a similar effect to a constant speed prop, or at least negates the need for variable pitch, and electric motors are well suited to the task since their torque is effectively the same at any rpm.

 

Once you reach a safe height after takeoff, power is reduced to a cruise/climb setting and at cruise altitude the power is pulled back to 40hp, the engine/alternator will quickly recharge the batteries. Then you can resume cruising flight at 50hp.

 

If the engine/alternator fails at any time during the flight, you still have 20 mins of battery power to fly to a safe landing place. This means you don't need an engine that is 'aircraft spec', so cheap auto conversions, motorcycle engines etc could be utilised.

 

Thoughts?

 

 

[bexrbetter]

You said " Your RC power trains are simply not scaleable. "

Yes I did and sticking with it, I did not say electric motors were not scaleable as you replied.

 

we are seeing some very well funded companies now look at electric power trains

 

it seems inevitable that they will be overcome in the near future.

You guys do know how long this has been spun for don't you? Google something like "new battery tech just around the corner..." or similar and see just how many years it's been going on for.

 

I have spent on and off the last 5 or so years looking for a viable 'new energy' product to manufacturer, it doesn't exist nor is it soon to. China is understandably desperate to lower their reliance on coal and would throw trillions at the right product, it ain't happening. If BYD China, the world's largest battery manufacturer as well as a major car manufacturer can't do it , nobody can.

 

The increments of development are minute and only fine tuning of what we already know and have and no one has yet resolved the cost issue.

 

 

[bexrbetter]

If the engine/alternator fails at any time during the flight, you still have 20 mins of battery power to fly to a safe landing place. This means you don't need an engine that is 'aircraft spec', so cheap auto conversions, motorcycle engines etc could be utilised.

Thoughts?

Basically sound thoughts but you wouldn't run a single system because the failures are most commonly controllers, leads, terminals and battery cell failure from overheating.

 

 

[Head in the clouds]

Basically sound thoughts but you wouldn't run a single system because the failures are most commonly controllers, leads, terminals and battery cell failure from overheating.

LiFePO4s don't overheat in the same way as LiPos, in fact their internal resistance will only bring their heat up to around 45C hence the need to heat them to get their internal resistance down sufficiently to get optimal discharge rates from them when high power is being used.

 

Also, I'm wondering whether you really need to use an esc for aircraft which don't typically require infinitely variable power, a range of, say, seven power settings might be sufficient in which case you could perhaps use series and parallel switching, tram fashion.

 

I can't see any need to accept terminal or lead failures if they're designed to have sufficient capacity for the task.

 

 

[eightyknots]

Whatever the CURRENT problems with electric drive trains (no pun intended), it seems inevitable that they will be overcome in the near future. RC speed controllers etc may not be scalable, but an electric motor is an electric motor whatever the size so I think you're arguing over 2 different things.I'm very excited about full size electric flight. Don't know that I'd fly into a thunderstorm though....

I think the current problem can be pretty much summarised in two words: battery capacity.

 

Until the battery capacity kg/kg comes reasonably close to mogas or avgas, large-scale adoption of electric flight is not going to happen.

 

 

[boingk]

The only practical way to go is series hybrid electric, and it has many potential advantages.

Series hybrid electric? Really? What are the benefits over a conventionally powered craft?

 

The earlier comment about outrunners not being ideal because of the issues of cooling the windings isn't the case if you use liquid cooling, in fact you need to use outrunners in that case so that the windings are wound onto a stationary core which is drilled with water galleries.

At this size an outrunner isn't a big deal because you have the size to use a suitable inrunner, and cooling shouldn't be an issue to start with due to proper engineering of the motor. You would NOT want to use a motor too small for the craft in either takeoff or cruise.

 

Batteries at this stage need to be LiFePO4 (Lithium Iron Phosphate) LiPos are too dangerous as they could catch fire. Lithium-Air batteries won't work in this application because they're not rechargeable.

Lithium-air aren't *yet* rechargeable. Like I said, they're in development. LiPo was originally a pipe-dream, too, but for now its what we have. Lithium Ferrous Phosphate (LiFePO4) batteries do not have the power density of LiPo. They are more stable but stability isn't an issue with proper management for LiPo cells - anything will break if you flog it.

 

The prop can be optimised for cruise and for a two seat LSA type it might be set up so that it absorbs about 40hp.

Or you could use an inflight adjustable prop.

 

Approximately 15-20 mins of battery capacity (at 40hp) is all that is required. The 'range extender' engine/alternator (which can be mounted anywhere in the aircraft) needs to be about 50hp.

And that will weight how much? And burn what fuel? Fuel engines are at best 30% efficient, and you'll reduce that output by 10~15% by running a generator... and then that gets reduced by 10~15% by efficiency losses in the drivetrain.

 

If the engine/alternator fails at any time during the flight, you still have 20 mins of battery power to fly to a safe landing place.

Assuming they got recharged!

 

I'm not trying to tear it apart, I'm just providing a counterpoint for the ideas. I like the idea of an advanced hybrid aircraft but I don't think current technology would make it efficient at all.

 

I *do* think a diesel aircraft would be a good option, especially if it was turbocharged.

 

Cheers - boingk

 

 

[Head in the clouds]

I think the current problem can be pretty much summarised in two words: battery capacity.Until the battery capacity kg/kg comes reasonably close to mogas or avgas, large-scale adoption of electric flight is not going to happen.

Using a series hybrid setup as I described you only need about 20kg of batteries because you only need enough stored power to fly the plane at 40hp for 15-20 mins. One 18Ah 14.4V LiFePO4 battery only weighs 1kg.

 

Series hybrid electric? Really? What are the benefits over a conventionally powered craft?

As mentioned previously, you can use cheap non-aircraft engines to run your generator. You can locate the engine to best advantage. You only need a 50hp engine instead of 100hp engine so it's smaller and running at its peak efficiency. More to the point with an electric motor you can have 150 or 200hp for take-off which is when you need the power. With a conventional aircraft setup you're carrying around and running an engine of say 100hp to be able to cruise at 50hp, and you can never get 200hp out of it for take-off.

 

At this size an outrunner isn't a big deal because you have the size to use a suitable inrunner, and cooling shouldn't be an issue to start with due to proper engineering of the motor. You would NOT want to use a motor too small for the craft in either takeoff or cruise.

No such thing as too small, it all comes down to the rate of heat dissipation. The length of time you can run an electric motor at any particular power output depends on how fast you can get rid of heat, nothing else.

 

Lithium-air aren't *yet* rechargeable. Like I said, they're in development. LiPo was originally a pipe-dream, too, but for now its what we have. Lithium Ferrous Phosphate (LiFePO4) batteries do not have the power density of LiPo. They are more stable but stability isn't an issue with proper management for LiPo cells - anything will break if you flog it.

I've read a lot about them but not seen anything indicating that anyone's trying to make air batteries rechargeable. In any case it's not likely to provide us with anything substantially better than we have. Lithium is the lightest of all metals and the electrolyte in LiFePO4 batteries weighs less than 10% of the total so there's not much to be saved by getting rid of it. Lithium batteries are already only about 10% of the weight of gel cells so if we're looking at electric we might as well accept what we have for now. The only likely major step forward might be in fuel cell technology/cost.

 

LiFePO4 batteries are within 5% of the power density of LiPos ...

 

Or you could use an inflight adjustable prop.

Why go to all that extra expense, weight, complexity and cost when the characteristics of electric motor torque make them completely unnecessary? That would be throwing away one of the major benefits of electric power.

 

And that will weight how much? And burn what fuel? Fuel engines are at best 30% efficient, and you'll reduce that output by 10~15% by running a generator... and then that gets reduced by 10~15% by efficiency losses in the drivetrain.

Weight should be in the same ballpark as present aircraft powerplants but take-off power, which is what we're really after would be double what we have presently. Bearing in mind that our rate of climb is dependent on excess horsepower, i.e. over and above what we need for flight at the climb angle of attack, then doubling the horsepower would make a mind blowing difference to the climb performance. Say you have 100hp at present and need 60hp to fly at 10* angle of attack for climb. So you're climbing on 40hp and getting, say 1000ft/min. Now give your plane 180hp instead. Your excess horsepower jumps from 40 hp to 120hp so your climb rate increases to 3000ft/min. Now you only need to use that high power setting for about 40 seconds to be at 2000ft. Electric acually gives you a huge benefit and power burst performance complies with a law of increasing returns, instead of diminishing returns, for once.

 

Yes there are efficiency losses but there are gains too, as described.

 

Assuming they got recharged!

I don't follow ...?

 

I'm not trying to tear it apart, I'm just providing a counterpoint for the ideas. I like the idea of an advanced hybrid aircraft but I don't think current technology would make it efficient at all.I *do* think a diesel aircraft would be a good option, especially if it was turbocharged.

Diesel engines could be used for the generator, unfortunately they don't seem to be working out so well for primary power-plants, the torsional vibration issues seem to be playing havoc with broken props and gearboxes.