rtfm
Well-Known Member
Hi guys,
Look, I know little to nothing about electrical stuff, so I'm asking questions which might seems absurdly simplistic. But bear with me please.
I know that there have been a number of threads deasling with electric powered planes, and I've read them all. Including the mega-thread on the RC forum dealing with the electric Lazair. But I get lost in the technical details.
So my question is simply this:
Can some one explain to me (in one syllable words) how this lot works? As far as I can tell, if you have a motor running off some batteries, your flight time is limited by how much energy the batteries can store and deliver. However, if you charge the batteries in flight, so long as the amount of energy one pumps into the batteries is equal or greater to the amount of energy they are supplying to keep the electric motor running, you're OK.
So, let's assume one has a 1Kw motor. How much battery does one need in order to keep this motor running for one hour? That would seem (to me, at any rate) a fairly basic bottom line. The supplementary question is then what size ICE would one need to keep this battery topped up?
It would seem sensible to assume that to keep a 1Kw motor running, one would need to supply at least 1Kw of charging power.
If this is the case, then a 35Kw motor (for example) would require a 47hp ICE to keep the batteries happy. Is this correct? And a 25hp ICE would supply only half the charging capacity required. In this case, the batteries would get charged, but at about half the required rate. Instead of the batteries lasting one hour, they would now last 90 mins. A 12hp ICE would prove a quarter of the required charging capability. The batteries would run out after 1.25hrs
The actual durations are indicative only, but am I on the right track?
If so, one would have to decide on a required flight duration (3 hrs?) and then figure out how much battery vs how much charging capacity the ICE could provide, and find a happy balance between actual battery capacity and charging capacity to provide the target duration.
I need help to get my head round this.
Anyone keen to give my education a fair go?
Cheers,
Duncan
Look, I know little to nothing about electrical stuff, so I'm asking questions which might seems absurdly simplistic. But bear with me please.
I know that there have been a number of threads deasling with electric powered planes, and I've read them all. Including the mega-thread on the RC forum dealing with the electric Lazair. But I get lost in the technical details.
So my question is simply this:
Can some one explain to me (in one syllable words) how this lot works? As far as I can tell, if you have a motor running off some batteries, your flight time is limited by how much energy the batteries can store and deliver. However, if you charge the batteries in flight, so long as the amount of energy one pumps into the batteries is equal or greater to the amount of energy they are supplying to keep the electric motor running, you're OK.
So, let's assume one has a 1Kw motor. How much battery does one need in order to keep this motor running for one hour? That would seem (to me, at any rate) a fairly basic bottom line. The supplementary question is then what size ICE would one need to keep this battery topped up?
It would seem sensible to assume that to keep a 1Kw motor running, one would need to supply at least 1Kw of charging power.
If this is the case, then a 35Kw motor (for example) would require a 47hp ICE to keep the batteries happy. Is this correct? And a 25hp ICE would supply only half the charging capacity required. In this case, the batteries would get charged, but at about half the required rate. Instead of the batteries lasting one hour, they would now last 90 mins. A 12hp ICE would prove a quarter of the required charging capability. The batteries would run out after 1.25hrs
The actual durations are indicative only, but am I on the right track?
If so, one would have to decide on a required flight duration (3 hrs?) and then figure out how much battery vs how much charging capacity the ICE could provide, and find a happy balance between actual battery capacity and charging capacity to provide the target duration.
I need help to get my head round this.
Anyone keen to give my education a fair go?
Cheers,
Duncan
