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» 2019 Llanfair TH Village Fete
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Saturday 7/7/18

2018-07-07, 21:07 by Gary M Jones

I was at the field today between 14:00 & 15:00 all on my own , good flying too. There is a dead sheep along the fence line towards the gate from the pits, I saw the farmer so reported this to her. I hope no one had plans for a BBQ Smile .

Farmer …

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Post by Guest on 2009-05-17, 22:01

shes backSniper returns Snip11

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Post by Andy Sayle on 2009-05-17, 22:45

More POooooowwwaaaaaaaahhhhhhh!!!!

I got the motor ready Wink You got an ESC that will be alright up to about 60Amps plus?

Cheers
Andy

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Post by Guest on 2009-05-17, 23:46

will have soon as i fix marks. my 80amp one and bec are on marks cheesy fan. have had look round and people are running the mega motor on 5 cells with a meaty heatsink getting upwards of 1kw Twisted Evil

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Post by Andy Sayle on 2009-05-18, 09:36

You will definately need a mega heatsink at that sort of power level! The power dissipation in the motor is going to be huge at those levels... That said, on a 5s pack, they will only be pulling 60 amps or so....

I reckon a nice light setup would be best in the Sniper though. Keep it down to a 3 or 4s 2150mAh pack, and run it at about 40-50 Amps for 400-500 Watts.

I've got an ESC, but it is only rated to 35 Amps. It did tend to limit the current (or just cut out!) when used at around 40A on the MiniFan and a 4s A123 pack. perhaps not the best choice for the Sniper!

Cheers
Andy

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Post by Guest on 2009-05-18, 16:08

andy do u have a couple of capacitors suitable for an 80 amp speedo. ive got some 1200uf ones but there only 14v. marks managed to pull them off his speedo when he crashed his yak. suppose they would be ok upto 4 cells.

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Post by Andy Sayle on 2009-05-18, 16:40

I'll have a look around the lab at work, and see what I can find Smile Regarding the voltage rating of ESC capacitors, then generally you want a bit of headroom in them. You have to allow for short-term voltage spikes (I need a blackboard to explain why!), so for an ESC that is to be used with 4s lipos (16.8v freshly charged) I would be looking at using a minimum 20v rated capacitor (25v to be on the safe side)....

Generally, the bigger the capacitors, the better!

Cheers
Andy

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Post by Guest on 2009-05-19, 00:10

getting closer. mark kindly donated a pair of very slim dymond d60 servos for the wing. its sooo thin. Got those mounted up and a hs85mg up its backside taking care up the uppy downy controls. need to make a battery tray for the cockpit can fit a pair of 3 cell 2150s in there to run in parallel should provide the motor with all the amps it can gobble. What a Face

only thing is what to do with the grey nose, should i paint it white again with the orange stripe? i do like the look of it all clean and pointy Razz

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Post by Andy Sayle on 2009-05-19, 09:45

I would go for the orange stripe, if you can get a paint match. A plain white nose will be a beeeyatch to see against light cloud.

Or, you could go all military on us, and paint the whole thing in grey? Add a few black markings for contrast, and you're laughing.

No luck on the capacitors as yet Sad

Andy

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Post by Guest on 2009-05-19, 21:17

i didnt go with orange and white What a Face

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Post by Guest on 2009-05-19, 21:42

here we go had a play with the airbrush. not perfect but was good practice. really needs a transparent or candy blue to give it some depth but i only have opaque.
Sniper returns PICT0069
Sniper returns PICT0072-1
Sniper returns PICT0080

the layers going on dont show up too well

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Post by Guest on 2009-05-19, 21:43

the last one is with a coat of clear satin.

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Post by Andy Sayle on 2009-05-20, 11:07

Blue flames, cool!

I've not got any suitable capacitors for the ESC leigh. the only big uns I can find at work, are rated to 500volts, and are the size of a coke can Sad

It might be worth a trip to maplin or Ebay for some. Thats said, the ones you have will work up to 3s lipos, but I wouldn't risk them with a freshly charges 4s lipo. When you start to over volt a capacitor (especially an Electrolytic one) you risk breaking down the insulation, and causing an internal short. this is usually followed by a small bang, and a bit of smoke! The best case is that the insulation inside holds up, but the capacitance rating drops quite severely. When put on the input of something pulling large current spikes (like an ESC Smile ) you then risk overheating, followed by complete failiure. interestingly, when the caps fail on the input to an ESC, it usually results in the ESC going pop too Shocked

If you do buy some, look for 25v rated ones. they will be good for 3,4 and 5s lipos. You may also get away with 6s lipos on them too. I fyou are planning to run a 6s pack, then I would look for 30v or 35v rated ones... As for the size (in µF) you want as much as possible! The big value caps, tend to be rather large though, so you need to choose one that is big enough in value, but not overly large physically.

Cheers
Andy

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Post by Guest on 2009-05-20, 13:25

thanks for havin a look andy. will order some from ebay. you can get em in small numbers without payin silly postage.

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Post by Andy Sayle on 2009-05-21, 12:01

Stop the press!

I've found a couple of 1000µF capacitors rated at 25v at work! They are about 12mm diameter and 41mm long.

I'll bring them with me this evening if you want them Smile

Andy

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Post by Guest on 2009-06-02, 10:27

flown on 4 cells last night. getting very quick now What a Face

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Post by Andy Sayle on 2009-06-02, 11:49

Good stuff!

How's the motor handling it? Hot? I'm not sure I'll be down the field tonight, but will definately be there on thursday. I'll bring me meter with me, and you can measure the juice it is pulling Smile

Andy

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