Umi_Ryuzuki

I guess the question should be, do you need both vertical propellers?
Will one be sufficient?
Also, once you get the landing skids on the vehicle it should be fairly easy to ballast.

One other thing, you might include a scale reference for the drawings.
Currently, the camera housing, could be as small as a soup can, or as large as a 1lb(1.87kg) coffee tin. It is difficult to tell.

Freakazoid

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The tubes are 10cm diameter, and 11cm in length. Basicly because a servo needs 5cm from the center, to make the camera tilt decently. I could use microservos and use 5cm diameter tubes, but thoe servos are so expencive, its not even funny. And about the 2 thrusters, good point, theres no reason for having 2 instead of 1.

sh0my

This design will probably work if you manage to balance it with the weight distribution. In my opinion it will lack maneuverability or will be hard to handle because it is so small and compact. Underwater the bigger and heavier things are generally easier to handle.

You could use only one vertical thruster. BTW, those vertical thrusters are displayed in wrong proportion when considering all data that you presented. If you use 10cm long stuffing compartment/tube, the motor with coupling is at least 5cm more, prop mount is also 1-2cm and you need another 1-2cm to seal the back end of the thruster. when you add all this together you get 17-19cm, which is almost twice as much as diameter of your tubes. On your drawings the vertical thrusters look shorter or the same as the diameter of the tubes. Maybe you don't need 10cm of stuffing, but you need at least 5, so still this is the wrong proportion.

Have you decided which motors, shaft diameter, coupling and prop will you use? These will determine the design of your thruster. I have been testing few combinations of those and it is not an easy job to find the right combination. As you will soon see, the frictional losses for the shaft going trough thick grease are considerable, also forget about shaft tube stuffed with grease, you loose too much power and grease will be washed away quickly. Better go for one grease filled compartment and the other air filled just in case of any leakage. Put the small bras or bronze sleeve bearing on the propeller side of stuffing compartment, if you use more powerful motors place another on the inner side.

I also had problems with vibration, guess the couplings I used are not good enough for the high reving motor. Generally, it seems better to use gearbox to reduce the revs and gain in torque, thus the loses are smaller and it is easier to manage the design, but I can't find small enough gearbox to fit in the truster compartment for my speed 600 motors.

Freakazoid

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1st of all, proportions are just fine. The downward thrusters dont need long shafts, as theire only possible leak is also the lowest point of the sub. And there has to happen perty much to have it end up upside down. The airbubble trapped inside is kind of a natural waterseal. The side shafts is another thing.

Wich shafts n such I should use, Ill have to have a look at that.

A helicopterlike landing rail might help alot as I could slide 2 weights along the shaft until its nicely balanced, and keep the weight nice and lowcenter. I think it ll need quite some weight to get it down though, get a fairly inflated party baloon, and try to sink it in your tub. :P Thats about the same quantity of air thats going to be inside the sub.

I dont really like the sideways thrusters being sofar back though, they probably make for a rather crappy turning circle.

I forgot why I used 2 thrusters, It was because I wanted to use 2 smaller motors instead of 1 thick one to keep the sub from becoming unpracticly long for agile movement (Wich it is almost now, really).

I wish I knew a way to make the camera turning tube smaller, but the big servos are keeping me from doing so. If I could reduce the cam tube, I could get the sub half as long, and more squarelike, looking from the top, wich means it has easier turning capability. I suppose there arnt any cheap round, planetgeared RC servos?

And about the weight being better when higher underwater is a bit different I think. I think the smaller the volume of water the craft takes up, the more agile it ll be, but it ll also sacrefice stability. Basicly It comes down to this: Bigger = Harder to push around, thus more stable. Smaller = Less waterdrag, so easy to shove around.

What this means to a small craft like what Im attempting?
It will be quite nimble when thetether float isnt pulling it, but that float might get the best of it because of its surface drag.

Freakazoid

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*Bump*

Heres the finished one. This will work, right?

sh0my

Hmmm...you really need to put centre of gravity lower. You should have those landing skids bigger & lower to have the possibility to put weight low enough to stabilize it. By enlarging skids you will also prevent any underwater plants or junk messing with your propellers. This 'flat' shape is not so popular with underwater ROVs because it is not easy to balance. As you have seen, vast majority of u/w ROVs and AUVs have larger height than width.

I think I have found the perfect solution for your camera case. Look:


This is the protective case from blank CD-Rs 100 pack. It has been sitting if front of my nose for days, and yet I have not noticed it till yesterday... You can find these with blurred and with very clear plastic. This one was clear when it was new (few years ago) but now it is all scratched up and bit cracked. I think you can find one easily, and it will cost you almost nothing.

EDIT: You are too fast...I need few minutes to figure this out..

Freakazoid

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You forgot the image url dude.

And Ive seen quite a large amount of ROV's, and they where nearly all bulletshaped or atleast flat and long. Just like this one. The rails can be a bit lower indeed, perhaps I could use some copper tubes, and fill em up with lead. nice n hefty.

EDIT
Heheh, Ive got plenty of tube recource. I can get anysize, any color. :P A tube like the one the camera is in, costs only 5 dollars or so.

Jonaz

Hi!
Im also on my way to build a UV ROV. but i have some problem to with the prop axl sealing. how have u fix this problem?

//Jonas

Freakazoid

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Read the topic for several solutions..

Freakazoid

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*Blows dust off topic title* -UGHE-COUGH-COUGH-

Hi,

Ive put this project on ice for quite a while, but Its defrosting as we speak.
This time the royal dutch navy is involved!

I pitched the plan about a submercible scout vehicle to my friend who happens to have a job in the navy, and he offered to help me with finance and construction, so I cant go wrong here. [8D] He's also got access to the good stuff, like watertight ballbearings, and CNC machines, so building will be a breeze.

Heres the latest Revision:


This one seems flawless. The 2 balasts sticking out like mickeymouse ears, are there to provide top stability. Due to the fact that its topside buoyancy is larger then the bottom of the sub, it wont roll over like a pig in the mud [&:]. Im also thinking of putting on a metal fin on its belly, to weigh it down a little and to make it easier to balance out its CoG.

Note:A navy specialist had a look at it, and told me this thing can go to atleast 150 meters (500ft.) depth, if I use 5mm PVC tubes!!
This brought the problem of the cable being way to long to get dragged around by the sub, if it has to be max length all the time..
Two solutions sofar:
1. Build a little wire-reel attached to an old windup clock spring, in the antenna buoy, so it kinda automaticly reels in the exces wire.
2. Use 3 meter (10ft) wire segments and add to adjust to required depth.

My navy friend will come over next week to start construction, so ill see if I can post some real pics for a change.
(Though it wont be much more then pics of a wallmart raid and some gathered heaps of parts for a while. [sm=stupid.gif])

RockGuitarist109

Hey it seems like ur sub is like mine, im also building one out of pvc pipe. and working on the watertight buisness, but i think i got it down. , and by the way grinding down the prop for higher speeds worked for me, I was using a 4 inch aluninum prop, but i shaved it down, and it mover faster and more steadier for me, P.S. im only 12 years old, but the reason y im building this is because i want to get godd at engineering so i can become one of those really good ones like on monster garage, thanx,
Joe

RockGuitarist109

sry but the last comment i didn't notice there were 4 pages i was looking at the last post on the first page when i wrote this

shaneperch

Those are awesome ideas!!!!! can anyone send me email wise drawings directions? Soon I am going to post (if anyone would want them) my PVC submarine directions. I have hear of a 33 inch Revell model. would that make a good RC sub? What kind of motors are you gonna use on the ROV?

RockGuitarist109

hey when u get those pvc directions send them to [email protected] ignore the email address, it wasn't my idea on what it should be. im trying to build a pvc pip also

shaneperch

You got it!!!!!! I want to help anyway I can!! thanks Tom.

Freakazoid

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Im also going to use small props to get it running on speed400 motors without reduction.

But I think ive got a problem...
Will AA battery's withstand the surge its going to give, when im piloting around with four speed400 motors?

Freakazoid

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A little update.
The motors and screws came in today.



oooooooh shiney! [8D]
6blade speciall submarine screws that wont cavitate + 4 nice fat motors.
My marine friend also managed to get nice chunky 7amp giant NiCd cells from his work at a supply ship,
12 of em in total, theire gonna run in 2x6 configuration to get 7.2v 14Ah.
Plenty of power for a machine that will fit a 35x25x30cm box.

Thats the start of the project. Stay tuned.

shaneperch

http://members.rott.chello.nl/rengel...section_16.htm Here is an excellent link for ROV construction!!!! it is great. Just some more ideas to look at. Tom

Freakazoid

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Sweet, thanks.

Freakazoid

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-New Update-
Engine pods got milled.







Rather smashing.

5mm thick aluminum shells, with a watertight cap, especially made to fit the motors.
We chose aluminum because it will help cool stuff better, rather then plastic tubes.