Freakazoid

My Feedback: (1)

Plenty of room for big honkin slabs of lead. Wich it will probably need anyway. (Ever tried sinking a beachball? Excactly.)
As currently planned, there are regulair 1:1 transmission speedprops on it. The sinker motors are 280 motors, as I think thats enough when its well balanced, and the manoevring props are speed500 or even 600, as its a fairly small vehicle, and as already said, It has to tug along quite a bulky floater and some wires.

Also Im thinking of putting the wire exit hole of the sub slightly backwards, so the pulling of the floater wont make the sub tilt nose up.

sh0my

I did some testing this weekend, on direct drive Speed 600 race is over 13A with 42mm dia 59mm pitch, and suffers a dramatical decrease of rpm, so it would suck up more than 13A with strong enough batteries. The thrust you get is tremendous, I hardly managed to push it down in the bathtub with my hand. Little bit later coupling between motor shaft and propeller shaft broke, so i had to stop the testing. These race props are intended to be used semi-cavitating and semi-submerged, so when you sink them completely you need much more power to keep them spinning.

There is also one other problem, it will be difficult to find adequate method to seal the shaft because it heats up a lot form all the friction, that speed 600 is reving at 21k!!

So for those vertical speed 280 find some small props with small pitch, or you will not get far with it.

Freakazoid

My Feedback: (1)

Those props are quite troublesome, and basicly the most crussial bit of the entire machine.

How about this:
Get a load of small aquarium pumps, like 6 of em. Give each of em its own nossle, and try to manoevre it with those. Im not sure howmuch pressure the pumps ll have to dish out to even move the craft though, and frankly I dont think a regulairsize aquarium pump will be able to deal with it..


Im running out of options here.. Its beginning to get frustrating, and the 1st thoughts of abandoning this project already came up..[:'(]
Theres just not a broad enough market for submerged vehicles, so getting any decent props and watersealed motorpods is a terribly expencive undertaking.
.. Another dream bashed I guess. []

But enough sobbing.
If I dont bump in to an easy solution soon, Ill just pull the plug on this one, and start looking for another crazy gig to try and build.


[offtopic]
Anyone knows another cool Idea to do with a camera besides the car, plane, and boat?
[/offtopic]

LtDoc

...Hmmm. How about mounting the camera ~low~, as in under one of the bumpers? Ought to make for some interesting shots. Bad idea for wet weather, and you'd want to shield it from 'stuff'. Also makes a nice rear view 'mirror'.

I don't think I'd give up on the ROV though. The prop/motor thing really isn't that difficult to 'get around'. You just don't need huge motors if the ballance/buoyancy is done right. Try designing from a different approach. Decide on some system of motors, equipment, payload, and such. Position things like you think they should be, then design a housing around all of it, rather than designing a 'shape' for the vehicle then cramming everything inside it. Since a ROV isn't going to be particularly fast and aerodynamic/hydrodynamic, the final 'shape' can be almost anything (within reason, sort of). The pressure at 10-20 feet isn't all ~that~ much. A 2 liter 'Coke' bottle should handle it well with a little stiffening (don't know how you'd get everything through that little 'neck', though). Pressurizing the hull isn't unreasonable either (metal air valve from the auto-parts house?). All kinds of possibilities if your mind is 'open' enough. Crazy ideas are only crazy when they don't work, so, go nuts and see what happens...
- 'Doc

Freakazoid

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If I made everything how I think it SHOULD be, id be looking at a custom machined nylonepox hull, and a bill thats around 5000 bucks or so.
The best design, looking at aquatic movement only, would be a long tube with impeller props at front and rear, with 2 turning props in the middle.
Something like this:


But unfortunatly that would require shapes and parts I cannot make/get with the tools/budget I have.


EDIT:
Ive found something that looks stupendously simple.
http://home.comcast.net/~homebuiltrovs/mule.html
Check this out. How simple can you get it. Look at how rediciously small the motors and props are.
Maybe I should settle with this design and drop the much more fancy lakefloor view for a straight forward one. I could still make it so it can look down, somewhat though.
But I think the lamps are a bit hard to make tilt aswell. The nob ontop might just aswell be a wire outlet. the motors are so small, I might even throw in a small lead acid battery and make it wireless afteral.

LtDoc

Freakazoid,
That 'MULE' seems like a well thought out, and 'frugal' (cheap LOL) ROV, and should withstand the pressures it will normally encounter. Before I would be comfortable with the size motors he'll be using, I think I'd give it a test first. They will probably work fine, but not knowing anything about them, I'm 'chicken', would rather see what happens. If/since you would be using a tether slightly larger motors could be used because you wouldn't need the 'on board' space for batteries.
Something that just occured to me is the weight of the tether, or it's buoyancy. If the tether doesn't have neutral buoyancy, then you would need more power to control the weight as more tether was paid out. Or, be able to change buoyancy of the ROV to compensate. 'Best' case would be for a tether with neutral buoyancy, though. (Oh boy! Another problem to play with! - LOL).
- 'Doc

PS - If a turret mount for the camera is too complicated or expensive, why not use two cameras, one straight ahead, one pointed down, then switch between them?

Freakazoid

My Feedback: (1)

2 cameras is even more expencive, And another thing, I could fit a big battery in a tube like this, but Im a bit concerned about the lighting problem If Id do so.
The lamps that are needed to see underwater might get very ugly for the power reserves. I could make a little something that kills the sinker motors and lights as soon as a critic low battery level is detected, so I can surface motor it to shore. He is just submerging his motors though, so that doesnt solve much.

tsunami

what about jet drives for e-boats their sealed and they should mount with little mod to the basic design[link=http://www.hobby-lobby.com/jetdrives.htm]graupner jets[/link]the mini is only 38 bucks

Freakazoid

My Feedback: (1)

I think id youd need at least 6 of those. :P Kinda expencive.
Nice try.

LtDoc

Freakazoid,
If you haven't already, take a look at the topic "Drive Systems" just above this one. Then go to the links for the torpedoes. LOTS of nice information there that might be helpful!
- 'Doc

Freakazoid

My Feedback: (1)

Ive seen it, the double 2way propellor is quite something, but that machine is built for surface pressures only I think.

LtDoc

Freakazoid ,
True, the housings as shown probably wouldn't stand a lot of pressure. But, at 2 or 3 meters there won't be all ~that~ much pressure anyway. The type and size motor was primarily what I was directing you toward. Small, compact, fairly small size prop, etc. Strengthen the housing a bit, and tack one on each side of your ROV. You really don't need the counter rotating props, a single should work just fine...
- 'Doc

Freakazoid

My Feedback: (1)

Are you saying I should just use axlegrease filled tubes for the watertighting of the motor pods?
And another thing, how would I fit those long pods on it as sinkermotors, without having a little twin tower floater going on?

LtDoc

Freakazoid,
Yes, axlegrease is one option. So is the grease used on fishing reels, or a heavy oil though I'd think the oil would be sort of "iffy". There still may be some leakage, but probably not much. The one thing I'd NOT recommend is a water soluable type lubricant ('Vasaline' is water soluable).

The torpedoes probably wouldn't work very well for the motor pods for vertical movement, some other arrangement would be necessary. Depending on how the buoyancy works out, the motors wouldn't have to be huge, small ones would probably do fine. High speed to dive, slow speed to maintain depth, and off to surface. (Worst case, pull on the tether? LOL) A lump/bump/pod on the top of the ROV with the prop sticking out??

An option for multiple cameras is to only switch between the actual 'camera' sensor/'head'. I've no idea what they cost, but the sensor component alone should be much cheaper than the whole 'camera' assembly. The switching can be done either electronically or by using a very small servo. That would mean either another channel in the radio or some sort of fairly sophisticated electronic switching via the camera system. Both are possible. You would have a much better idea of cost than I have...
- 'Doc

Freakazoid

My Feedback: (1)

Have a look at this:



Fairly nice, but the bottom prop seems to be begging for a rockbottom meeting.
It would work, but it 'd need some protection cage. And the camera BADLY needs a dome and some swivelpoint on the cam, so it can see the bottom aswell. You might think "Why is he so persistent to have both frontal and down views?" well, im planning on hovering around down below under the docks at the local harbour, and it would be rather nice to keep an eye out for struts and other stuff like boats.

What exactly do you mean with those sensors?

Ive been thinking of some usefull utility modules to put on:
- A small metaldetector. (a friend said its fairly easy to build)
- Hoovering device that sucks up and spits out the sand to dig things up. (perhaps together with the metaldetector)
- A rather powerfull magnet, to cling onto something
- Maybe a gass bag transporter made out of a CO2 carnister and a tough balloon to float heavy stuff up so it can tug it to the side and within reach.
- A little clamp to grab, tug and pribe stuff thats not metal, or rather stuck under something.
But thats all just dream stuff though. First off, I need the main pod.

tsunami

the little claw is the only hard one to do out of all those
otherwise itll be great but your desing wont really aloow for soem of that to work especially the arm as it will always be messing with the attitude of the sub

Freakazoid

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I have to figure out a way to pick stuff up from the harbour floor, like RC boat parts and even an RC helicopter thats crashed on the water. Basicly Im hoping those lowpower electronics survived underwater. Some of it might be rusted though, but most marine ESC's usually can withstand long submerging. It might be a hoot exploring it a bit. [&:] Who knows what elce ill find. Besides, just so you know: Its a calm inland harbour without a current. Its a dead end to a river, so no nasty wavebobbing or dragging that it has to cope with.

As for the claw, maybe this is an idea: A servo triggered, spring powered jaw, that klings to the hull of the sub by a magnet. Also theres a nice nylon tether attached to the gripper for me to pull on once its hooked onto something. Then youd just position the jaw, snap it shut and give it a good reverse thug, so the magnet yanks off, the sub is free, And I can start reeling it in... Did you understand that?

tsunami

yup but now your talking a seprate system for the claw as its only attached to the sub by magnet. or is a severable link going to be used.

Freakazoid

My Feedback: (1)

Probably the activation mechanism will remain on the sub, only the mechanic bit comes off.

But back to the sub itself.
How to see frontal and below, with 1 cam, and still have decent prop mounts.

LtDoc

Freakazoid,
"Sensors"... Not the correct name for them, but my memory isn't the best today (or this month!). The actual device that detects the 'light' is a small thingy about the size of the tip of your little finger. It's usually mounted on a curcuit board with the rest of the electronics required for it to work. A second device mounted at 90 degrees to the first shouldn't be difficult, then you'd only have to do the switching between the two. Know anyone who has an extra camera (or two) for a computer laying around?

The last set of pictures makes the whole thing look easy, well, almost! Shouldn't be a problem to make a prop guard for that design, or even recess the motor into the hull. Or put it on top? A spring loaded clamp for grabbing stuff should be fairly easy to make too. A remotely controled 'arm' would be a different story, more complicated, but 'doable' (search for robotics). For things that are ferrus metal, a large magnet ought'a work (extra buoyancy, then watch the ROV pop to the surface when it's released LOL. Making attachments for the ROV will move your project into a higher order of magnitude as far as cost goes. It would certainly be 'handy' though...
- 'Doc

Freakazoid

My Feedback: (1)

Right from the start I wanted to make a "Mother Pod", and after accomplishing that, Id go looking for some tool modules to strap, snap or screw onto that motherpod. End effectors, so to speak. But first things first, the motherpod.

The sensor youre reffering to, is probably a CMOS camera module? Getting one connected would be a real ******* to do.

Heres the camera im going to use.


As you can see, unfortunatly its an all in 1 camera, thus making it hard to modify, due to its really small SMD components.
You where probably thinking about those square transmitters with a camera plugging into it.

Options to solve the 90' tilt view ability.
[ul][*] Buy another camera, with a different frequency, make a channel switcher on my viewport, or get 2 screens. - EXPENCIVE[*] A mirror, like a baseballcap above the camera, so that when you tilt the camera WAY up, it ll have a direct down view. - Hard to do.[*] Half a bowl or some kind of dome. - Perfect, but getting one is nearly impossible without spending heaving wads of dough.[*] Some way of getting the whole sub to tilt. - Hard to do.
[/ul]


Ohyeah, and heres the viewscreen:

A nice 7" LCD screen. [8D] Ill have to make a antireflection cap (kinda like you see on traffic lights) so It ll be a pleasant view in broad daylight.

tsunami

why not use servos to change the view like some of the plane guys are doing

Freakazoid

My Feedback: (1)

Well thats the plan all along, but if theres nothing but wall to see, tilting the cam wont work...
So ill need a dome on the front, or some other way of getting the cam to have a front to down panorama view.

Another thing, someone said to put the prop ontop of the whole thing. That wont work because that bit will be above the surface line, so it wont have any water to push up.

LtDoc

Freakazoid,
Instead of tilting the camera, mount a mirror above the lens and tilt it into the camera's field of view which would then be looking 'down'. A sero with mirror attached ought to be cheaper than a camera. Think it'll work?
- 'Doc

Freakazoid

My Feedback: (1)

Cheers.
I dont really know how to do this so it still gives a workable size of view, and doesnt act as a huge drag while moving forward.
I think finding some plastic dome would be absolutly brilliant, but the shippingcosts from the US to europe makes me wheep .
Apparently europe is a domeless continent. [:@] Theres really no shop that I can think of wich might sell these, except the countless robotics shops you americans have.. Ive even seen the most perfect dome ended tube for sale in an american shop, 4 inches wide and only 6 friggin dollar, but 25 dollar banking fee, and another 25 for shipping. [:'(]
God I wish I was born an american....