Need help? Amphibious rc car

[sk11dn]

Hello,
One of my projects in my course is to make an amphibious remote control car, i would like it if people could contribute their thoughts and ideas?
Things you may want to know:
car needs to be electric
the car i'm using is a colt on road 4wd belt drive
body will be made of blue foam in any design i want
the car will go around a course that will be a loop shape, half water half land. So it will need to be able to steer in both.
i have 11 weeks to make this

My current thoughts have been from my research that nearly all amphibious vehicles are propeller driven. so i was just going to buy a boat it use its motors and propeller and possibly rudder to power it in the water, how would i use both electrics in the one car?

of course that idea seems pretty plain just making a boat and car into one. But does anyone else have some ideas? maybe someone has made one before.

i'm looking forward to your help, thankyou

[Ashley Cobb]

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[sk11dn]

I get what you mean, but i want the car to keep its peformance
Do you mean paddles like a paddle boats wheel?

[Ashley Cobb]

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[Target]

my thoughts where get a shaft driven car rather than belt drive, so you have a source of power that you dont have to change direction on.. That way you could either drive a prop off the main shaft (via some sort of belt) to an elevated airplane prop... swamp boat style..

or ditch the rear diff, go front wheel drive. some sort of universal joint off the end to a prop, like a regular boat.

I could have used such a car the past two race meets at tempe. nuff water sitting on the track.

[sk11dn]

Haha i was going to keep it simple, but i want to go all out on this project and make it the best one!
If i was install all the boat gear into the car, its possible for it all to run on the one controller, yeah?

[sk11dn]

"target" that is a good idea!
But i don't have a shaft car, i knew i should of got one because belts are going to be a pain when i try waterproof the whole car as well.

[WC]

put all your electronics in a sealed tupperware ABOVE the waterline


btw not sure if you realise it but many monster trucks with oversized tyres
have enough buoyancy to float... and paddle along slowly

the 1:1 Bigfoot does too!

[Dorigecko]

willy, good point.

I reckon start with some polyethylene foam, make a rough shape of the car, and shape it to go. all elec in tupperware like what WC said, motor will run underwater but it shouldn't go that far

you could always run a third channel for a rudder to your steering? have a second little motor mounted to a prop shaft to a propeller. run it off the larger engine power.

[contact]

electric motors are quite happy to run under water and some speed controllers (mtronics and LRP come to mind) will also run underwater, the receiver is a different kettle of fish im not sure there is an effectively water tight one?

you could run a 3ch radio and 2 speed controllers, one for the wheel drive and one for the water drive and put them on separate channels of the radio then you could have independent control of the land and water drive, or use both together

a relay could also switch between the two drive motors and use the same esc but you will still need 3 channels on the radio (3rd to switch the relay)

some ideas to ponder?

post some pics when your done!

[sk11dn]

sweet I am getting some great ideas here! I'm going to have to do some research oh these 3ch and 4ch controllers now...
I will be posting pictures of the build up of this rc car and other peoples in my class!
For now here is a picture of the teachers design. He did the project last year for the first time with the 2nd years and his was the only one that worked haha! He just used a $50 car, and if you look at the back wheels he has all these fins throughout the wheel that pumps water out the back through some pvc pipe, of course this a good idea but i don't want to copy him

[Ashley Cobb]

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[Ashley Cobb]

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[contact]

go speed racer!

[Ashley Cobb]

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[contact]

Originally Posted by Ashley Cobb

you could probably do this with a decent 2 channel radio and 2 ESC's

you would program them with reverse turned off, and program 1 in the full throttle position to make the ground wheels go, then program the other to full reverse (on the remote) to make the prop/motor go.

almost like channel mixing. basically you're programming 1 speedy to go when the trigger is forward and 1 speedy when the trigger is back

yep... you can also get pretty cheap mixers.

model engines did one in one of their nitro monster trucks, hold the brake on and it activated the reverse servo for locking in reverse gear, then hold brake on again to disengage reverse, that also would keep you in 2 channel mode and im sure you could work around motor control that way and keep the brake?

[Ashley Cobb]

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[contact]

yeah... i dont know if it would work or not... just a curiosity that came across my 'desk' once upon a time (in a land far far away lived .... ) but fits with the idea of using 2ch rather than 3.

it would be a lot easier to use 3/4 ch and they are pretty cheap... i wonder where the law would stand on using 36mhz, legal on water but not on land LOL!!

[Ashley Cobb]

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[sk11dn]

Why are they illegal?

[Ashley Cobb]

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[contact]

Originally Posted by sk11dn

Why are they illegal?

the ACA (or what ever the mob that manage the spectrum are called these days) allocate frequencies for r/c... 27, 29 40mhz and 2.4ghz are legal for use on land, while 27, 36mhz and 2.4ghz are right for air and water use...

unless this is an ongoing thing i would probably use 36 on the basis that its a watercraft... your not likely to get into any trouble + 36 in 4+ channels can be had pretty cheap (pm me i might be able to help with a TX)

[WC]

radio designations are Air VS Surface (=land/water)