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-   -   First Build Coro-airboat (http://www.rcuniverse.com/forum/rc-airboats-246/11591834-first-build-coro-airboat.html)

Akiyn78 12-21-2013 06:56 AM

First Build Coro-airboat
 
3 Attachment(s)
Building a 34x13x1 3/4 ep bl 1200kv on 7.4 1600mah lipo unsure of prop size. Tried a 9.4x4.7 sf, have room to mount a 12incher unsure of pitch any suggestions. This is a work in progress. have a mock up of engine mount, was strong enough to test. goes good on snow,faster on ice 13mph, maybe 20mph or so on water-not yet tested on water. Floats well tried in tub took about 8lbs to submerge hull at rear. So far no leaks..[ATTACH=CONFIG]1949687[/ATTACH][ATTACH=CONFIG]1949688[/ATTACH][ATTACH=CONFIG]1949689[/ATTACH]

Akiyn78 12-21-2013 10:55 AM

Looking for some input on prop size and type now using a s/f 9.7x4.7 with room to fit a 12inch or would an electric prop be better. Thanx in advance

Jeremy_H 12-21-2013 04:45 PM

I can't help you with the prop, I know nothing about brushless, but keep us posted on the model itself, I'm interested in seeing how it turns out with the Coro construction.

Got RPM 12-22-2013 12:32 PM

I may be able to help with the prop but I need more info. Exactly what motor are you using? How much does the boat weigh all up? BTW the boat will be slower on water than it is on ice....


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Akiyn78 12-23-2013 06:08 AM

it's a frio 12 , 1200kv. All up weight aprox. 3 lbs.

Akiyn78 12-23-2013 06:11 AM

tryed to use coro for frame but it flexes too much so gonna use wood is basswood ok, or do i need something stronger?

Got RPM 12-23-2013 02:39 PM

Your motor is rated for 150 watts which is just 20 amps on 2S. Running the numbers through a performance program, here is what I get for the APC line of SlowFlyer and EP props:

Prop........rpm.....thrust.....speed.....amps
9x4.7......6789.......14..........31..........9
10x4.7....5927.......19..........28.........13
11x4.7....5869.......20..........26.........14
12x3.8...4907........26.........18..........17
12x6EP.5037........22..........29.........17

From this limited selection, the "best' props are probably the 11x4.7SF and the 12x6EP props. What you need is high thrust plus a air high velocity. None of these props will give your boat much more than 5-8 mph on water, the motor just doesn't make enough power.



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Akiyn78 12-23-2013 08:11 PM

thanx, i kinda realized i was under powered...2nd option for power source is os max .41 or an os max .91 ringed engine, at least without buying a new bl and batt. Maybe its time to go back to the drawing board. bwt what program did you use?

Got RPM 12-24-2013 01:21 PM

Not certain the coro will last with the vibration of a nitro engine. I used ScorpionCalc, not an exact match for your motor but close.


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Akiyn78 12-25-2013 12:56 AM

Well guess i.m gonna order new bl and sc . Want to build a frame out of wood, will basswood or light ply be better. Main concern is weight, after frame and engine mount are built hoping to be under 5 pounds.

Got RPM 12-25-2013 09:33 PM

An extra couple of ounces of wood is meaningless for your build. It is wetted area which is the biggest contributor to poor airboat performance, something endemic to flatties. Use ply, it is less likely to warp but still needs to be coated with a water proof paint etc.


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Akiyn78 12-27-2013 03:21 PM

So while waiting for woodnew bl and sc i decided to build a mini. 18x9 1/2x1 3/8 inch. 1200 kv bl 20 amp sc 2s lipo 6x4 prop. iso water ..lbvs

Akiyn78 12-31-2013 02:39 AM

got my mini built. 17 turn brushed motor, 60amp sc, 2s lipo , 6 x 4 e prop. I'll try to get pic or video and gps it.test in basment motor and sc cool, but battery was warm almost hot.

Got RPM 12-31-2013 04:00 AM

Exactly what battery? You may not have enough battery for your system, or the pack didn't get all that hot as it is normal for the pack to warm up. Never get a LiPo above 140*F.



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Akiyn78 01-02-2014 04:37 PM

1600 mah 2s lipo. runs fine with bs setup, brushed moter & sc setup gets hot, maybe 90-100 degrees or so. this was outside with temp of 10 degrees.

Akiyn78 01-03-2014 10:43 PM

Boat put on hold ...trans blew in my Buick, there goes 1800 dollars... fml


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