G'day people,from here in Australia.
I assume this question has been asked before,but I can't find a reference to it.
Anyway my EV project is a electric Paramotor (smallest Aircraft in the world).
There is some really sweet projects happening and you all,should be very proud for at least giving them a go,whether they work properly or not.You might just crack the big one,of ideas.
Regards
MPW50.
Gday MPW50
yes you can mechanically couple an alternator to a motor.
but for what purpose?
a DC-DC is more efficient (kw out/kw in) and significantly lighter per kw of conversion than the above setup (which on an aircraft is rather important)
im assuming you are doing this to change the voltage? ie from traction pack voltage to 12/24v?
Matt
Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km
I would think he wants to do it to charge on the fly(pardon the pun), to increase range. And/or for emergencies.
Dave ; Tennessee
XB-600.
ah yes,
ive seen this before.
a wind turbine on an aircraft for power in the event of engine failure.
Just in this case the prop? is being reused.
my fluid dynamics is a lil rusty, but yes this should work.
I would probably go with using an AC motor to start with though (that already can do regen)
this would be more beneficially from a weight perspective.
out of curiosity, how much power does main motor need to move the aircraft along?
Matt
Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km
G'day Matt,
I mainly just wanted to know if it could be done first,then I'd decide. As I had been told that it could not be done. I have also invented a way to drive and connect the whole lot without connections.
(thin air if you will).
Thanks for your reply,
Regards,
Warwick.
Pun pardoned Dave,
and thanks for your reply.
And yes charge on the fly anything to extend flight time.
Regards,
Warwick.
Matt,
Power required is not as important as at least, 1.5 Nm of Torque and Rpm to match my prop which gives out, 50 kilograms of thrust @ 6,000 rpm and top speed of the glider,(called a soft wing) does not vary much from top speed of 36 kph of my glider.
Regards,
Warwick.
To be clear, using regen is to replace braking thrust otherwise created by air brakes to extend flight time?
or, during battery pack failure for instrumentation power (not propulsion)?
Matt
EDIT: clarified last sentence. regen used for powering instrumentation, nothing more.
Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km
Well, in general, you are talking about perpetual motion. If your glide ratio goes down because you are taking energy out of the system to charge your batteries, you are NOT going to stay in the air longer.
The only way I can imagine this working is if you have thermal or slope lift that is so dramatic that you can afford to use some of that excess lift to convert into electricity. Even then, it's not going to be very efficient.
In WWII, the WACO GC4 glider had a wind-driven generator for electrical instruments, but they weren't taking very much energy out of the airstream.
G'day Mark,
No I am not thinking of P/M,although an admirable endeavour.
There is a free commodity as a result of the thrust produced (very high speed wind) and I have figured out a way to exploit it.
An alternator or similar if it could be wired in,would help save a huge amount of weight and not end up as ballast(non-useful) 4.5 kg's ( for 60 + amps) is better than 10 kg's for 60 + amps in batteries.
When people talk of having space like a tank to fill with bits to make their cycle move,that is my total space to work with, about the same size as a rucksack strapped to my back and about the same capacity for weight,so everything is at a premium.
Thanks for your input,
Regards,
Warwick.
using the wind for power increases your wind resistance dis-proportionately.
If you try and maintain altitude and speed at the same time as drawing power from the wind, you are attempting perpetual motion.
This will *not* work.
Using an alternator to replace the main battery in a purely electric Aircraft will not work.
I cant stress this enough
there is no such thing as perpetual motion.
using the wind for power will cause altitude loss and/or speed loss. If that is the intention then yes it would work.
regen used in place of braking works.
regen used while trying to maintain altitude and speed does not work.
Matt
Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km
Here's another example of wind power perpetual motion:
http://www.youtube.com/watch?v=bkcn8ZkvKKc
It won't work in the air any better than it would on the ground.
G'day again Matt,
I am not using the wind for power at all.
You misconstrued what I said,I am using the wind created from the prop wash,(what's left of the Thrust) not relevant wind (what a moving body through air creates).
Some examples of what I can do are as follows :-
From a 1.5 volt EM,radio shack supplied for solar use I can produce 1.97 volts,using a 40cm desk fan on high = 20 kph of wind.
Full size version (early version) = 60cm using the same fan attached to an alternator (used originally for it's high inertia) went a staggering 12 r.p.m,s and about 120 r.p.m,s outdoors in a 18 kph wind.
Attached to a petrol paramotor at what would be considered cruising speed,(less than full throttle) pulls just over 5,000 r.p.m. (attached only to a bearing)
And attached to an Alternator ( which was only ever a thought,after I discovered that it performed so well) although I am unable at this point to test using the petrol motor,my tests show that 3,000 -3,600 r.p.m,s are achievable and more,with my best version which equates to around a potential 60 Amps from an Alternater with a peak of 80 Amps at 6'000 r,p.m,s
It was never a committed project just something I could try to reduce total weight.
Regards,
Warwick.
G'day Mark,
See Matt's remarks.
Relevant wind is not Prop wash and I had no intentions of trying it.
As a matter of fact your example has not only reached it's peak performance,but will only go slower and if nothing else relevant wind will finish the job,too much drag from all those impeller blades plus multi bladed impellers are too slow by there nature and useless.
Regards,
Warwick.
My apologies, this is where my ignorance with regard to fluid dynamics and aviation starts to shine through.
Matt
Daily Ride:
2007 Vectrix, modified with 42 x Thundersky 60Ah in July 2010. Done 194'000km
Matt,
No need for the apology,would have been better if I just got an answer to the question that was asked.I have found some interesting things from these pages,though.
Thanks,
Regards,
Warwick.
I haven't seen a electric paramotor yet, but electric trike-type ultralights and even a prototype electric light-sport plane has been built. Go here:
http://www.electraflyer.com/trike.php
I am still unclear what your proposed alternator would be for. If it is for regenerative charging when the motor is off, the motor itself can do that. But I suspect that with the drag it would produce, you would be better off with the prop stopped or freewheeling while you glide.
I fly hang gliders, so I'm familiar with some of the aspects of your project.
It still will not work! Even if the alternator is driven by blades powered by prop wash, you still need to apply a force to it which is equal and of opposite direction. This force will pull the aircraft backwards, slowing it down and reducing the overall efficiency to less than 1.
You could only use the prop wash if your generator was stationary, fixed to the planets mass. The energy then comes out of the planets rotational energy; the earth slows down (or speeds up, depending on direction) as the generator generates!
This information may be used entirely at your own risk.
There is always a way if there is no other way!
Hey MPW50, in answer to your question, any electric motor can produce an electrical output if it's shaft is driven by an external force.
The output voltage will of course be DC for a brushed DC motor.
An AC current can be gained from an AC induction motor if an AC voltage is applied and the shaft is driven by an external force.
A perminant magnet motor, such as a stepper motor is particularly effective, just put a bridge rectifier across the terminals to make it's AC output into DC.
In short, any motor IS a generator or alternator if you want it to be (and add energy)
As for the perpetual motion thing, it seems to me that any extra drag will be taking energy from the aircraft. You cannot get any free energy from any system, it is only possible to change the form of the energy.
To drive a small generator/ alternator with airflow will require extra energy input in to the propellor drive, or you will loose altitude.
I saw a video once of a snoozer from NZ who strapped a small wind turbine (1.5KW)to his car.
YAY, FREE ENERGY!!!!!!!!!!
No, of course he had to use extra right foot pressure to maintain the same speed, so in fact it cost him lots of extra Wheet-Bix in his breakfast to keep his energy up to enable him to press firmly on the pedal.
Extra petrol useage..........who cares, cos he got free energy!
So, yes you can make some power from an auxiliary fan/generator. But it will cost you more than you gain in energy.
By the way, you mentioned making voltage with your experimental setup, but I recon that as soon as you try to drive a load, the voltage will flatten and the net output will drop to zero.
I suggest a solar cell would be a better bet all 'round.
Cheers PN
Paul
G'day Paul,
Yes I am well aware that any motor can be used as a gen etc (see what I have already achieved).
I am not after anything for free quite the contrary.
A Paramotor basically unlike other aircraft only has two speeds they are ;
1) Cruise which is maintaining level flight about 3/4 + of total power.=65-70 mph of wind.
2) Climbing full throttle only and usually in 5 minute bursts (engine will over heat).= approx 80 mph wind.
3) Anything under these is called gravity with obvious results and is controlled,by the normal glide ratio which is quite a bit less than the same wing used for paragliding only,about 4:1 instead of 6:1.
As I have already said it was only ever a question of could it be done,not I am doing this.
My reasons (and this applies to all who read this) the use of an alternator was only ever a means to an end,that being :
1) To make a contra rotating Impeller (sitting 6-10 inches behind the prop) to try and prevent a very serious accident that I had (I won't bore you with the details) namely Torque Reaction,although mine was called Precession the opposite to T/R but caused in theory by the same problem. (Also can be achieved using Mercury or similar switches).
2) As the success that I achieved only came about,because I figured that the only way to get the speed that was needed,was through some way of increasing the inertia that I needed to rotate.
All I had was a too small AC motor from the fan in a fan forced oven (it was too light).An AC fridge motor (it was too big and cumbersome).Only thing left and it was just right was the Alternator.We have a winner!!.
I live at approximately 1100 metres at every 2990 ft you get a 10 % power loss from a petrol motor,my motor is supposed to put out 50 + kg's of thrust,at sea level (due to some faults with it this figure has never been obtained) at my altitude it is,well short of this figure but with my blade,attached to nothing other than a bearing and plate can pull the full figure or near enough.Which means it makes thrust of it's own.
I have only ever ground tested and won't ever air test,until I am sure if it all works properly.
Since and it was only ever a thought that the alternator could be driven,by the air from a fan then perhaps greater results,could come from the prop and it did.
Therefore rotational forces would be no different than those achieved,from a standard car set up,i.e. V belts but with a different type of connection. Forgive me for wanting to try something new.
So if the rotational force is achieved an Alternator will work,regardless of the method of that rotation and as long as 1,800 rpm (speed at which excitation begins) is reached,it will work and produce approximately 50 % of the power available and since the only motor,not run directly or indeed at all by the Alternator is the Electric Start.So I think it is a logical Question.
What I know of fluid dynamics fills the head of a Pin,but it does say it should not work.
If I had known about Betz'Law used in Impeller Design (I was looking to see if I had achieved, anything at all.see Wiki or Danish Wind Works.com),I would not have tried to do what I did,as it tells me as well that it could be done.But an early version bettered it by 21 % it just so happened,that their version of measurement was the same as I used,seemed to give the best results.
Either way work or not using the Alternator,I have achieved my goal and would just like to find more uses,I put a lot of work into it and therefore should be able to get out of it,what ever I can.
Regards,
Warwick.
G'day Paul,
Thanks for the link,had not seen it before,anything else you need to know ckeck out the previous entry.
Have a look on U-tube for footage of EM PP/G's and Paragliding Forum.com for more info.
Regards,
Warwick.
Read a later entry,
Regards,
Warwick.