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CAP 21


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  • 2 weeks later...

Gary

This is Peter's Cap 21,free plan,it was so good and it flew a treat so I scaled it up to 60" with a 61 up front and it flew just as well.

I know you are doing the 20l but they are much the same so you wont be disappointed with the result, good luck with the build.

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Hi All

Update on the CAP 21 I have started on the wing construction as seen below

20140413_202252.jpg

This is not a one peace wing it is left and right side

i had the plan copied and the wing section reversed a lot better than trying to build one wing on the otherwink

20140413_202256.jpg

20140413_202301.jpg

need to visit lms for some ply to finish off smiley

Doing the wing construction this way is a lot quicker and much more accurate and only cost £1 for the copy yes

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gary sorry for the late reply. i have been busy wrestling with my hedge in the garden and building a park for the kids . i have managed to get all the major parts cut and ive got some of the port wing done . ive time of this week so am hoping to get some done, ill post you some pics when ive got something worth seeing , fly low

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IMHO a 2A BEC will be more than enough for 4 standard servos under normal operation with a 3s LiPo. I think the only time you might see a full 2A drawn is if all 4 of those servos are stalled at the same time, which shouldn't ever happen in flight. Maybe in crash scenario though? However, if a 4s LiPo is being used then I would recommend the use of a UBEC.

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Perhaps I'm overly cautious, Bill, but it's paid off for me so far. I agree that 2A is unlikely to be drawn, all being well, but being a linear BEC, and on 4S, it will be working hard and producing heat. If the motor is propped to draw near the 50A ESC limit, there'll be some heat there too. I think overworking ESC/BECs is probably one of the commonest 'radio glitches' in leccy flight....sad

For the sake of less than a fiver for something like this, I don't think it's worth taking the chance smile

Pete

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Bill_B

Whilst I agree with your statement, the capacity needs to be high enough to handle peak current draw - this will vary and for very short periods the servos may pull higher currents. Depending on the design of the BEC it may or may not be able to supply momentary higher currents so I too would go for the 3A option

Obviously a NiMH or similar pack can supply very high instantaneous current bursts but a BEC may not

Edited By Masher on 14/04/2014 08:05:26

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