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[terry1956]

Hi out there. I purchased a sub that needed some tlc.  And I need some help with the dive system. The lower hull is split into sections. The front section holds an air pump. This feeds two small paint cylinders in the second section, air being taken from that  section and compressed in the cylinders. There are two wires from the air pump, pos and neg. my question is what is the best way to control this pump. And from where do I purchase the bits needed within the uk. Thanks.

[microgyros]

Hi out there. I purchased a sub that needed some tlc.  And I need some help with the dive system. The lower hull is split into sections. The front section holds an air pump. This feeds two small paint cylinders in the second section, air being taken from that  section and compressed in the cylinders. There are two wires from the air pump, pos and neg. my question is what is the best way to control this pump. And from where do I purchase the bits needed within the uk. Thanks.

The arrangement of the ballast is the way Wullie Guthrie built his Darnell sub. I can't rememember if he built a T or S class.Anyway,  his sub (U.S.E. pump, servo & microswitch ballast + AST pitch control on the dive servo + RC) worked and sailed well enough with nothing more, nothing less.

[terry1956]

Thanks but how did he control the air pump. What parts and who sells them in detail.

[microgyros]

Please understand there have been so many "how to" books and other publications and you got a short, speculative reply amounting to:- you might have such and such, built by so and so, which uses this gear, based upon
two small paint cylinders
inside the ballast tank
air compression pump

[Fred Ellis]

Hi Terry 1956

Have a look at this site https://www.theassociationofmodelsubmariners.com it should have some of the answers that you are after.

Fred

[warspite]

Pictures also would help in identifying the parts you have

[RST]

I found some info on Google by looking for "U.S.E. pump, Darnell submarine".


I just put "U.S.E. pump" in first and presumably that's not the original mechanism that was showing up -perhaps it is? Don't check on a works computer! LoL

[Subculture]

They were a little oscillating steam engine used by Darnell in the earlier days of the hobby. Rigged to an electric motor, they can move air about, but they tended to be rather leaky without modifications. Most replaced them with a small compressor culled from the small 12v tyre inflator units you can get in Halfords etc.

Nowadays there are excellent small diaphragm pumps available secondhand on ebay for a few pounds that work much better provided you don't want to pump higher pressures (e.g. over 5-10psi).

The main snag with compressed air is that it can be harder to control for fine trim, so most systems using it tend to have it as a binary system- full or empty, and use an additional trim tank for fine trimming that last 1% of variance owing to water conditions e.g. temperature and mineral content.

Where a single tank system is desired many now use water pumps as they allow fine control and are easier to check.