Hodders Posted June 23, 2016 Share Posted June 23, 2016 Anybody seen the following website: http://www.exomo.com/ 28kg includes motor and battery and gives 60 mins (don't know at what throttle) with 50 to 70kg thrust depending on prop. Sooo close to getting there. Even with that setup you can always upgrade the battery tech as it changes. Quote Link to comment Share on other sites More sharing options...
cas_whitmore Posted June 23, 2016 Share Posted June 23, 2016 I'm not really in to electric paramotors but I must admit I would seriously consider one . There's one place I can fly but it's very noise sensitive ' just needs to be a few kgs lighter for me . cas . Quote Link to comment Share on other sites More sharing options...
Steve Posted June 23, 2016 Share Posted June 23, 2016 You're over ten grand already with that and you don't even get a chassis, harness or cage, etc. Lovely idea but way too expensive to be competitive yet. Quote Link to comment Share on other sites More sharing options...
cas_whitmore Posted June 23, 2016 Share Posted June 23, 2016 Your right don't think we'll be seeing them at field anytime soon '. Shame. cas Quote Link to comment Share on other sites More sharing options...
Hodders Posted June 23, 2016 Author Share Posted June 23, 2016 The big hope is the big push by companies like Tesla for automotive applications. The motors are already there, we just need the battery tech to improve. I am convinced it will happen. The benefits are huge - prop noise will be the same (and is not insignificant) but reliability and cost of use will tumble compared to 2 strokes. Just need the batteries ! 1 Quote Link to comment Share on other sites More sharing options...
ptwizz Posted June 24, 2016 Share Posted June 24, 2016 With regard to electric powered vehicles, be it cars, bikes or paramotors, the common theme is "we just need the batteries". There are some fundamental limitations of physics which just aren't going to go away. For a battery to be rechargeable, it must retain all of it's matter during discharge. This means it can't release much energy, certainly nowhere near that which can be released by combustion. It also has to carry all of it's 'fuel' even after it is discharged. Petrol has about 50 times the energy density (kWh / kg) of the best modern lithium ion batteries. There is a theoretical lithium oxygen battery which could get closer to the energy density of petrol, but there is a lot of development needed to overcome the somewhat explodey nature of the prototypes. Quote Link to comment Share on other sites More sharing options...
admin (Simon W) Posted June 26, 2016 Share Posted June 26, 2016 I would love to see Graphine do its thing in my lifetime!! thats going to turn batteries (as we think of them now) on its head. SW Quote Link to comment Share on other sites More sharing options...
fuzzybabybunny Posted June 26, 2016 Share Posted June 26, 2016 Just how much quieter are these electric paramotors? You've still got the noise from the prop which isn't going away. Does this mean you can fly without hearing protection? Quote Link to comment Share on other sites More sharing options...
ptwizz Posted June 27, 2016 Share Posted June 27, 2016 As I understand it, graphene has the potential to approximately double the power density of lithium polymer batteries. Graphene is simply a thin carbon carrier which replaces the polymer carrier. The battery chemistry remains the same, it's just the packaging that is reduced. This still leaves the battery at 1/25th of the power density of petrol. WRT noise, yes, prop noise is unchanged. A Bailey 4 stroke motor is almost inaudible over the prop noise and you still need ear protection. Quote Link to comment Share on other sites More sharing options...
christian Posted June 27, 2016 Share Posted June 27, 2016 Noise? They had an electric paramotor flying at Blois last summer. It was not significantly quieter than a Miniplane. Christian Quote Link to comment Share on other sites More sharing options...
fuzzybabybunny Posted June 27, 2016 Share Posted June 27, 2016 Bummer. So I guess that prop noise is like 90% of the noise of any PPG unit then? Quote Link to comment Share on other sites More sharing options...
fuzzybabybunny Posted June 27, 2016 Share Posted June 27, 2016 (edited) 10 hours ago, ptwizz said: As I understand it, graphene has the potential to approximately double the power density of lithium polymer batteries. Graphene is simply a thin carbon carrier which replaces the polymer carrier. The battery chemistry remains the same, it's just the packaging that is reduced. This still leaves the battery at 1/25th of the power density of petrol. WRT noise, yes, prop noise is unchanged. A Bailey 4 stroke motor is almost inaudible over the prop noise and you still need ear protection. As I understand it, gasoline has an energy density of 36 MJ/L. Current batteries do 2 MJ/L (gasoline has 18x the density). Bleeding edge batteries have 4 MJ/L (gasoline has 9x the density). But let's not forget that electric motors are inherently more efficient than Internal Combustion Engines. ICE two-strokes are like... 30%? And they're fundamentally limited in efficiency by the Carnot Cycle. Electric motors are 95%. So - with current batteries with an energy density of 2 MJ/L, a 10L battery pack should be able to do the same amount of work as a ~2L tank of gasoline. A 10L battery with 4 MJ/L energy density should be able to do the same amount of work as a ~4L tank of gasoline. Now that's getting kinda close? But 10L of batteries would be quite a bit heavier than 2L / 4L of petrol... and 10L of empty batteries will be infinitely heavier than zero liters of petrol at the end of the flight Edited June 27, 2016 by fuzzybabybunny Quote Link to comment Share on other sites More sharing options...
alan_k Posted June 28, 2016 Share Posted June 28, 2016 Novel twin prop homemade electric paramotor: Quote Link to comment Share on other sites More sharing options...
ptwizz Posted June 30, 2016 Share Posted June 30, 2016 I was referring to energy density in terms of mass rather than volume, because mass is (mostly) the limiting factor in relatively slow flying machines. It is of course true that IC engines are limited to around 30% efficiency (2 strokes even less). While electric motors can be 95% efficient, I'm not sure that the brushless motors and their inverters are quite up to that. I'm not against electric flight, but I fail to see any significant advantage. It's no quieter than a 4 stroke engine, it's always going to be heavier, you need either spare batteries or charging equipment to fly more than once each trip out and it's expensive. The 'zero emission' argument is marred by the production processes of both lithium batteries and rare earth magnets and by the fact that we are still using fossil fuels to top-up our generating capacity. Quote Link to comment Share on other sites More sharing options...
calcifer Posted June 30, 2016 Share Posted June 30, 2016 I agree with ptwizz. There will come a day when ALL the propulsion engines will be electric, but that day has still to come... maybe 10, maybe 20 years or so. The energy density of the batteries is still a problem, together with the safety of the batteries. My father owns a Renault twizy, a fully electric quadricycle with abt. 80 km. of range @ full charge (3 hrs to get fully charged) which is not bad, but the battery pack is heavy and dangerous. It can easily ignite if punctured, so in order to meet the rigid omologation requirements the battery is closed into an armored case which increases even more the weight. This could be a secondary problem for a ground vehicle.... but a big problem for a flying vehicle where every additional kg. is not good. Let's wait and see..... Quote Link to comment Share on other sites More sharing options...
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