Hybrid Electric Paramotor

[custom-vince]

Next subject open for discussion..

25cc Engine turing 4x 12v Coils to produce 48v to turn an Electric motor for propulsion.

I know its more complicated but does the maths add up?

maybe need some capacitors etc. (no not a flux capacitor)

Little light weight economical 25cc engine. Does it have enough oooompf to turn 4-5 or 6 coils to power a turnigy motor and prop?

[bigpapa]

For a 20hp Electric Motor you will need to generate 20hp worth of electricity. Which will require a 20hp petrol motor. Assuming 100% efficiency. So as a straight replacement for the battery it wont work.

Although it could supplement a battery setup:

20hp = 15KW

at 48v this will have a current draw of 300Amps.

Assuming a 15kg LiPo Pack, giving roughly 50 Amp Hours (real world).

Assuming an average power requirement of 10hp (7.5kW : 150Amps)

= 20minutes flight time

You could use a smaller engine/generator as range extender in conjunction with a battery pack. But 20cc will only give about 2hp, giving a 20% range extension (5 minutes). This will be less (maybe negative) considering the weight penalty.

50cc? say 7hp? 70% extra. 14 minutes.

It would be a heavy setup though.

[Guest]

Nice answer.

I have seen that some car people are using a small Jet engine to charge batteries through an inverter to power electric cars.

SW

[custom-vince]

That makes some sense strait away. But how are they making diesel / petrol electric hybrid car or are they all just concepts.

240v 1kw generator. What is the amp output if it were 50v? I'm not up with this stuff. Just asking?

[outkast]

That makes some sense strait away. But how are they making diesel / petrol electric hybrid car or are they all just concepts.

240v 1kw generator. What is the amp output if it were 50v? I'm not up with this stuff. Just asking?

one thing electric vehicles dont have such a problem with as us is wieght, the prius is very heavy for its size

[custom-vince]

That has lots of heavy batteries. I'm looking at capacitors for their ability to take and discharge power at high rates. My initial thing was direct transfer of power from dynomo to motor if you like. Been told it dont work like that.

[slim]

I'm going with the "it adds too much weight to be useful" school of replies. There are exceptions though. Most internal combustion engines are designed to provide useful power over a wide range of revs. This makes them less efficient at all speeds. If you can design it to be most powerful at a very particular speed, preferably the speed at which your alternator is most efficient, then you get a much higher power to weight ratio.

This fundamental design was used in older diesel-electric trains (who certainly didn't have to worry about weight too much). Petrol (or diesel) is a very efficient storer of energy... not least because half the fuel is in the air being pulled in to the engine. A battery powered system has to carry all its "fuel" in the weight of the batteries.

Then there are the capacitors as storage. To store large quantities of energy in a capacitor it would have to be huge. We've all seen the capacitors that the boy racers use to smooth power to their oversized amps in Vauxhall Corsas and yes, if you drop a screwdriver across the terminals you get a big spark and possibly a fire but that is a high flow for a very short amount of time. It is a tiny amount of energy compared to 300Amps for many minutes.

And finally, we come to efficiency. There is no way that all of this energy conversion is going to be anything close to 100% efficient so you'll be loosing heat all over the place.

It is a lovely idea but the physics are against you

S.

[bigpapa]

For capacitors equivalent to a 50Ah battery at 48V it would need a rating of 3750Farads. The big ones seen in knobs cars are typically 1-2 farads.

Also, Unlike Lipos which are pretty good at holding their voltage, capacitors voltage drops over time, so your power will drop over time, so you would need more capacity to compensate for this.

Capacitors aren't good for storing power. They are only good for releasing their stored power very quickly (over a few seconds).

They would make a good EMP when you have a dodgy landing.

Your generator:

1kw @ 240v = 4.16Amps. 1kw = 1.35hp.

If you used a transformer or different generator coil config to get this to 50v you would get 20Amps, still 1kw (1.35hp). Power out always equals power in minus inefficiencies.

The best working hybrid is the Lotus Evora 414E. It uses a 1.2l 48hp engine to top up the batteries. extending the range from 30 to 300miles. This engine is developed to work efficiently at a fixed rpm. Even so this still works out at 40mpg. not great.

The range extender in the Vaxhall Ampera is a 1.4l engine. So to get the range extenders to work in the real world they need to be nearly equivalent capacity to the normal engine you would expect anyway.

http://www.pistonheads.com/news/default.asp?storyId=26527

[custom-vince]

see this is why I chucked the idea up rather than spending time on google doing the maths. Simple strait forward answers to poo poo my idea. After the first answer I sat and throught more about it and ah yes no it wouldn't work. Back to the idea with the giant twisted rubber band as an engine...