Jump to content

Electric paramotor


Hodders
 Share

Recommended Posts

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 !

  • Upvote 1
Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

 

Link to comment
Share on other sites

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 by fuzzybabybunny
Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.....

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share



×
×
  • Create New...