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[gingyer]

Hi All
looking for some help I have a Sheerline Trafalgar Class, I can take the model down until the decks are awash no problems
but any input from the dive planes and the sub goes a bit mental either the back end drops or the nose dives right in.
I cant seem to find a way to stop this or control what happens.
both the rear and fore planes work each set has it's own servo controlling them and they are connected using a Y-lead
to a single channel from the radio
has anyone got any ideas in what is causing it or how to fix it?

thanks
Colin

[sheerline]

Hi Colin.
Can you be a bit more specific? Are we talking about a radio problem with possible interference or some other problem with the setup of the balance of the boat as it submerges?
If in doubt and you want to discuss it , give me a call tomorrow and I'll try and sort it out for you. If I have to go out, leave your number on the answerphone, I'll get back to you.
Chris

[gingyer]

it doesn't seem to be radio interferance I watched it close in at the side and no interfrance was seen on the dive planes
it is as if the balance goes and it starts falling forward or backwards so you need to empty the ballast tank to surface it to get
it balanced again

I am wondering about fitting a level unit to the front dive planes. with the rear ones operated from the RX but I am not sure that would clear the problem up

[hollowhornbear]

try the leveller on the rear planes, front controlled from tx. as the rear controls the pitch the front controls the depth.

[Roadrunner]

Are you using a 2.4ghz TX/rx? as they can't work underwater... which may explain your issue. If you are swap to a 27 or 40mhz tx/rx and see if the problem persists.

[sheerline]

You may have some trapped air in the upper hull which may be moving around, this will lay havoc with the boats stability.
Does this boat have a lead acid battery in front of the dive unit or is it the later MK2 version with the NiMh battery underneath?

[Sub driver]

bin the y lead. do as hollowhornbear has suggested . then all  will be well. regards sub.

[Mankster]

You dont really want the front and rear planes linked like that in a static dive boat. Have them under independent control or leave the from plane unoperational (I didn't even fit front dive planes to mine). I normally trim my subs to just the tip of the sail is above the water when the ballast tanks are full. Putting a bit of foam inside the sail prevents it from dropping too quickly when you fill the tank (once the hull is under water- decks awash- there is very little bouyancy left in the sail otherwise)

[gingyer]

Thanks all,
now to get a level unit installed and re jig the radio setup.
anyone recomend a nice idiot proof level unit? 

You may have some trapped air in the upper hull which may be moving around, this will lay havoc with the boats stability.
Does this boat have a lead acid battery in front of the dive unit or is it the later MK2 version with the NiMh battery underneath?

the submarine is a Mk1 with the SLA up front. I dont think it is air as their are plenty of air holes in the casing but I could be wrong....

Are you using a 2.4ghz TX/rx? as they can't work underwater... which may explain your issue. If you are swap to a 27 or 40mhz tx/rx and see if the problem persists.

It is a 40Mhz set

[sheerline]

Hi Gingyer.
The Mk1 needed a bit of foam front and rear in the upper hull, countered by a bit more lead under the dive unit. This gave the boat a lower c of g and made the boat stable when submerged. Without it, the boat would have a tendancy to either drop it's nose or tail at random due to shifting ballast water in the tank. Foam front and rear was standard practice on the earlier boat and once you have resolved the problem it will dive and run like a dream.

[gingyer]

Hi Gingyer.
The Mk1 needed a bit of foam front and rear in the upper hull, countered by a bit more lead under the dive unit. This gave the boat a lower c of g and made the boat stable when submerged. Without it, the boat would have a tendancy to either drop it's nose or tail at random due to shifting ballast water in the tank. Foam front and rear was standard practice on the earlier boat and once you have resolved the problem it will dive and run like a dream.

Sounds like what has been happening to me ....so foam it is and possibly a level unit for good measure
Thanks Chris appreciated 

[Brooks]

A level unit, or leveler, is for fine tuning the boat's attitude. That is, you dive to a desired depth, then, when the joystick is centered, the leveler removes the (small) dive angle of the hull. Ditto if you ascend. Your problem sounds more in the nature of a uncommanded/undesired gross attitude change. The other poster's suggestions should help you solve the problem, I think. Air bubbles are the bain of a model submariners existence You might also check that the planes don't make uncommanded moves when you tilt the sub by hand on land. Something could be sliding  eg. ballast,  or servo tray.