Negative Box Compression

[junglelord]

Negitive Box Compression
It happened to me today with my Robbe SeaWolf. I dived too deep.
It went straight to the bottom and got stuck in weeds.
:mad:

I sat on the river and said a prayer...and low and behold some guy came singing, down the river, on a sea kayak.
I'll drink to THAT!

He retrieved my sub and at five feet it came up on its own, none the worse for wear, but truly a voyage to the bottom of the sea.
:p

[toppack]

How did he get it loose from bottom?
Did he dive down to it?

[junglelord]

I had found a long stick with a fork at the end lying on the beach.
He simply put the fork under the sailplanes and got it out just like that.
It began to rise on its own around six feet. It was about 20 feet out and about 16 feet down. Just a little too far in that freezing cold water...especially for me with my spinal cord injury.

But it has no problems, other then me learning the ups and downs of submarine protocol. I put Blue RTV on the pushrod seals and the drive shaft tonight. I used some vaseline on the O rings today. The new front end cap seal with the 5mm thread and the O ring and washer and wing nut make that sucker tight. Now to stay on top of things with pre and post checks. But happy to say that it handled large swells today and cuts through them like a hot knife in butter. I can walk up the ridge and watch my control planes very clearly and just walked along the shoreline up on the ridge and practiced keeping it level. I need a ADF and that will be a better cruise. However at present, on a simple three channel and no reverse, its quite fun. I look forward to upgrading to the five channel and the ADF.

[Slats]

And this my friends is an yet another example of why Dynamic Divers - too deep - won't simply pop back to the surface.

Question is how did you let yourself get that deep?
Answer often I have found is the boat requires a fair clip of speed to stay dived, high speed - slight down angle on the rear planes and rapidally you can find yourself much deeper than you intend.

Glad your sub was retrieved.

Best
John

[Albion]

Ok im not a guy with the experience of some others around here, however i would like to use my dive training here. As a diver descends he becomes more negative because his airspaces are being compressed by the pressure of water, and adds air to his bouyncy device to offset this. For a diver it is a easy skill to master, but something which requires complex electronics and monitoirng device for a model submarine. So when we look at our models the hull is open so not a probelm, the WTC in most cases is non compressible so agin our relative bouyany should not change, and what is neutral at 1 foot should be neutral at 10 feet. Bellows type seals can be compressed and will have some effect to make the boat negative, but not much. So the problem lies in the foam we fit to trim the boats, this is clearly compressible.

So what could be used to create positive fixed bouyancy which is simple and not to costly???

[He Who Shall Not Be Named]

Ok im not a guy with the experience of some others around here, however i would like to use my dive training here. As a diver descends he becomes more negative because his airspaces are being compressed by the pressure of water, and adds air to his bouyncy device to offset this. For a diver it is a easy skill to master, but something which requires complex electronics and monitoirng device for a model submarine. So when we look at our models the hull is open so not a probelm, the WTC in most cases is non compressible so agin our relative bouyany should not change, and what is neutral at 1 foot should be neutral at 10 feet. Bellows type seals can be compressed and will have some effect to make the boat negative, but not much. So the problem lies in the foam we fit to trim the boats, this is clearly compressible.

So what could be used to create positive fixed bouyancy which is simple and not to costly???

The significant fraction of compressed items aboard the submarine is indeed the WTC/SubDriver.

David,

[Albion]

The significant fraction of compressed items aboard the submarine is indeed the WTC/SubDriver.

David,

Really, that suprises me.

Is it the tube itself? or the seals deforming

[Subculture]

Robbe boats don't use any foam for trim.

I wonder if in this instance radio signal loss was the culprit. Have you got a failsafe on the throttle, i.e. chop the power on signal loss?

[Slats]

What David is saying was very observable with my old ballast system (pump into sealed compressed tank) and with boat operating in Olympic Dive pool with 5 m floor.

Typically you loose signal probably before 4 m - but had a rare opportunity with operational control ok at 5m at this particular pool.

Parked the boat on the bottom - had her set up to run a little positive but the deeper I went the heavier (negative the boat was). In fact I was letting, via the clippard valve holding the water in the tank against the air the water was compressing, a little water out trying to hold on to a neutral type state as I went deeper. Scary thing was I parked the boat on the bottom, went off had lunch, and then tried to drive up. Usually if I depressed the clippard valve control at say 2 -3 m she would rise like a cork, but i blew the tank at 5 m and the boat took over a minute to lift off the bottom whilst I had full RC. A bit like DAS Boot blowing for ages and nothing happens and then it gets going.

J

[junglelord]

Robbe boats don't use any foam for trim.

I wonder if in this instance radio signal loss was the culprit. Have you got a failsafe on the throttle, i.e. chop the power on signal loss?

Not sure that I had any signal loss, just dove too deep and she went too the bottom as John explained, is exactly what happened.

And this my friends is an yet another example of why Dynamic Divers - too deep - won't simply pop back to the surface.

Question is how did you let yourself get that deep?
Answer often I have found is the boat requires a fair clip of speed to stay dived, high speed - slight down angle on the rear planes and rapidally you can find yourself much deeper than you intend.

Glad your sub was retrieved.

Best
John

[junglelord]

Good thing I got her back too, I am off to the Mall with my wares for the local RC Flying club display....trying to sell the public on the art of Submarines.
I'll drink to THAT!

[He Who Shall Not Be Named]

Good thing I got her back too, I am off to the Mall with my wares for the local RC Flying club display....trying to sell the public on the art of Submarines.
I'll drink to THAT!

CRAFT! ... not 'art'. Art is for fag's!

David,

[toppack]

CRAFT! ... not 'art'. Art is for fag's!

David,

Yes, there's nothing Artistic about David, he's Just 'Crafty'. :D LOL

[junglelord]

CRAFT! ... not 'art'. Art is for fag's!

David,

With an attitude like that, you may need some sales pitch designed by fags...
:p

[redboat219]

the problem lies in the foam we fit to trim the boats, this is clearly compressible.

So what could be used to create positive fixed bouyancy which is simple and not to costly???

I was thinking in the lines of the bathyscaphe. (These submersibles use a float is filled with gasoline which is readily available, buoyant, and for all practical purposes, incompressible to maintain positive boyancy.) but instead of gasoline we could use something like vegetable oils.