Thread: Build Log Nan Orion
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Old Nov 02, 2012, 05:15 AM
ditman is offline
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Hi Dick,

Don't worry - I am not going to screw this up by trying to do everything quickly I'm not committing to any system until I have thought this through.

I went over my previous posts and it seems I have done a good job writing down every second thought I have and creating a lot of confusion

Let me start from your setup: this, for me, is a standard, something to compare with and, quite possibly, the EXACT one I will use. I always like my planes light and certainly I am not going the way of 200g+ motors with 1000+ watts of output! Not that I have anything againts these - I will just not be able to handle the damn thing!

So, if I like your setup so much, why do I consider changing it? Well, the only (REALLY MINOR) issue is that the setup is at its limits: this is a 300W system that runs at 400W and pushing it further would be probably too much. Now, I certainly don't want 1000W, but 600 or maybe 700? I am sure 400W is more than enough for this ship and me for now, but maybe I would like something more after I get to know her better

What I am trying to say is that I consider accepting 100-150g of extra weight, if this would result in a more versatile system. And this brings us to the setup I proposed:

ASSUMING the motor fits and the whole thing balances out, I think my proposal would fit the bill. According to my calculations, I would be heavier than you by: 45g from the motor (170g instead of 125g) and another 25 from the ESC, i.e. 70g. I understand you are using a 2200 3S battery, so that would be about the same. The only other difference is the BEC, which could add up to 15g more, but I ALWAYS use BECs in my birds, especially if I expect the ESC to work close to its limits.

So, as you very correctly ask, what would I get for these 80-90g? Well, the proposed setup would have much more output than yours. I mention a couple of examples of props, but these are actually meant to show that the system can easily produce power close to the one you use (obviously, not well explained in my post). However, the system could do much better: the motor is rated at 55A max, so it could probably be pushed to 60A for short bursts, i.e. 600W+ on 3S. Using a 4S battery (another 50-60g more, so still no more than 150g heavier than yours) it could produce close to 750W for short periods.

Therefore, if the proposed system balances, I could start with a prop consuming 350-400W (this would be equal to your setup, but 80-90g heavier), then move up to 500 or 600W just by changing the prop (so, I end up with more power with this 90g extra weight). Theoretically, one could then move even further up, by changing the battery to 4S.

Finally, the setup offers one more option, which created confusion in my previous post. The idea of this option is that you could have a prop that could be used both with 3S and 4S. Obviously, in order to keep down the wattage at 4S you need a prop that would be rather small for 3S. This results to my proposal of a prop that consumes around 35A in 3S: obviously, this setup is heavier than yours and has less power; nonetheless, the trade-off would be that you could also fly with much more power using a 4S. So, you arrive at the field and feel like TD – you throw the 3S in it; you want something more edgy – use the 4S. Obviously, whether this versatility is worth the increase in weight and reduction of thrust when working with a 3S, is up to one’s personal taste

Sooooo, after having (hopefully) explained my thinking, I will now wait for the ship to arrive. Once here, I will see what I will do

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Last edited by ditman; Nov 02, 2012 at 05:22 AM.
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