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Old Nov 24, 2003, 08:24 PM
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What C40 for Corona w/ TP6000 3S3P ?

I have a C40 12S on my 1st Corona, which I use 8 Cell GP3300's on, and get about 10 minutes.

I am building a 2nd, and want to get the duration of TP LiPoly.

What I am unsure of is how high to go with the Hacker windings to compensate for the 3S voltage. I want to get about the same power.

I tried the TP on my C4012S. It is very light, and bobs up and down in hover. Either accelerating up, or drifting down. Difficult to stabilize.

I know I should go to a C40 14S minimum. I wonder if I should go to 16S or beyond?

Any ideas? Anyone have motor calc and wanna give me some advice?

Thanks, Jim

PS: I know there are 2 dot blade grips available, and this may help, and I know I cant let the revs get too high....

I think you actually need to keep the weight not too much lower than stock, given the blade size. Thats why I went with 3S3P. It is about the biggest you can fit inside. And I do have it fitted. You just need to account for the 2 inch width of the battery, by moving the 1/4 inch stiffener a little higher.
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Old Nov 25, 2003, 11:39 AM
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Corona W/Hacker C40's & 3s3p Li-Po:

I have a set of parameters for MotoCalc that I have used to check my Corona with various brushed & brushless motors that matches closely what the Corona actually does. For you cases, I ran comparisons with your current C40-12S and the Nimh's against the TP3s3p with the Hacker 14S & 16S. My conclusions are that as you found, the 3s Li-Po on the C40-12S is too much. You could see 2600 RPM on MR speed with 4/6 grips at full throttle, giving about 146 oz. of thrust. I have found that in the 45-48 oz. AUW range, the Corona will hover nicely at about 1500 RPM MR speed. So you have way too much excess power there and must keep way down on the throttle where it is very touchy.

If you move to a C40-14S, the full throttle MR headspeed is down to about 2400 RPM and thrust about 121 oz. Compare this to your current setup with the C40-12S on 8 Nimh's which is predicted to give 2200 RPM and 104 oz. static thrust at full throttle. So if you like the response on your current setup, the C40-14S is still too much. I don't think the blade grip selection range will get you close enough and I am not a fan changing the gear ratio from the stock 11.3:1.0.

If you go to the C40-16S, the full throttle headspeed will be about 2175 RPM (4/6 grips) with thrust of 100 oz. This is just slightly less than the current setup you have. You could then use the blade grips to fine tune it and probably get very close.

I tried to use your stated 10 minute flying time on the Nimh's to characterize an "average" flying style and throttle setting. If I use that power/thrust for the 3s3p with the Hacker C40-14S, I project you would be averaging about 75% throttle and get about 23 minutes of flight. Going to the Hacker C40-16S, you would be averaging about 80% throttle and get about 24 minutes of flight. As a reference, I estimated the throttle at an average 79% for the Nimh flight time you stated.

So you can see that the C40-16S looks close to what you are use to. However, you will have a little more throttle reserve to play with if you go with a C40-14S with a slight decrease in typical flight time. If you don't find yourself pushing the throttle to full while flying your current style, you may not need the reserve power of the 14S. Also the throttle for hover on the C40-14S will be about 15% points less than both your current setup and the C40-16S so you will be in a much touchier range like you found when trying the C4012S on Li-Po's

I have been told that the Li-Po batteries start off on full charge with strong voltage for the first 2-3 minutes but then drop down for most of the remainder of their discharge. I am not sure what the data in MotoCalc uses for Li-Po internal resistance, so be aware that a 14S Hacker could be a bit touchy for the first part of a flight or that the 16S might not seem quite as peppy as your current setup toward the end of the flight.

Do you think all this will help you make your choice? Good luck!
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Old Nov 25, 2003, 01:55 PM
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Spec's for C40-12T

I have a co-worker that just bought a C40-12T.

Does anyone have any spec's on this motor such as RPM / VOLT?
We have gone into the HUCKER WEB SITE and nothing!

Thanks in advanced!
Carlos
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Old Nov 25, 2003, 02:22 PM
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Aerospacer, thanks very much for all the work, and a very thorough answer.

This confirms about what I thought without the right tools (software). I am using a spreadsheet.

I will consider a 14S or 16S....probably tend towards the 16S, but will be wary of power droop.

I just want to be sure the motor will scale properly for hover. The 12s is barely controllable, but I did not try exp, or other adj.

I have abso thought about an AXI 2820/10 or 12 outrunner.

This would be cool cause it is different, and cheaper.

I would order a belt drive from here:

http://www08.causemann.de/netware_bu...9343db56d468e7

The motor may just fit.

thanks again.

Carlos, the Hacker site has the Kv

It is here:

well, the hacker site is down today!

here is A/C world.....a good place in Japan to buy from.

Dont know if he still ships hacker to the US

http://aircraft-world.com/products.asp?id=16&pg=2

the 12S is the same as a 12T in the US

Kv = 3500 rpm/v

Jim.
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Old Nov 25, 2003, 02:33 PM
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Thanks! I am doing homework!
CARLOS
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Old Nov 25, 2003, 03:06 PM
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Well that sounds boring! I flew today!!

But I suppose it is always good to do your homework.
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Old Nov 25, 2003, 06:18 PM
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AXI 2820 in Corona:

I found the KV's for the two winds of this model at 1100 and 900 RPM/Volt. With them that low you would have to have about a 3:1 reduction to keep the max MR speed at 2000 RPM. The belt drives you pointed to only go as low as 5:1.

Maybe you meant the AXI 2814 model which has a 1270 and 1520 KV wind. Using the 1520 KV with a 6:1 belt reduction (the best of the combo's MotoCalc tried) you will get 96 oz. of static thrust and 2100 RPM MR speed at full throttle with 6/6 MR grips. You could see a 3-4 minute increase in your average flight duration above the C40-16S but you may not have quite the throttle reserve for aerobatic stuff or the "back-end" of the Li-Po battery capacity.
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