Gas conversion.....

[subkraft]

Recent project....over the years I seem to have accumulated several of these older subdrivers. Problem is that in this country the propel equivalent is very expensive and hard to get. Having not found a viable alternative source of gas.....have been looking at ways to convert them. This is my first attempt. The diving mechanism is retained as per original. In the new version the vent valve servo moves in the opposite direction to trigger a microswitched airpump. Like RCARBS, wtc internal air blows the ballast tank. Internal air replenished through a switched solenoid valve which opens a snorkel once sufficiently surfaced. There's a procedure required each time...but similar to full size practice.


New parts are in orange and fitted into the legacy resin wtc tube, motor housing and vent valve assembly. New bits 3d printed in pla. Dimensionally the parts print well, usually slightly oversize.


I've put this together as a best guess to test the idea....will fit into a Holland model, which has ideal vent tubes. Have doubts about air capacity within wtc, limited bore of the small solenoids to get sufficient replenish air in, degree of vacuum created in wtc by blowing the ballast among other things. Had hoped to get away without a float valve on snorkel....perhaps having some sort of drain for any water in it on surfacing.

Next step is to seal it up and run a few tests.

[JWLaRue]

Very nicely done. Will be interested in what your tests show.

-Jeff

[apa-228]

Why not eliminate the solenoid from the snorkel intake? I think making the snorkel head with a 180 degree inlet and a caged weighted float to blank off the suction piping while submerged could accomplish the same thing. The weight would only need to be heavy enough to drop the floa once it is noy bouyed up bt the water. It should also eliminate the drain you referenced.

[salmon]

What you are doing is what David has recently done (4-5 years ago) with his SAS system. He pumps air from the dry spaces into the ballast tank. When the sub surfaces an air intake opens up (snorkel).this way you can eliminate the gas portion although I do not recommend doing that from experience.

[PaulC]

Tom, are you referring to the backup Propel blow in the SubDriver?

[salmon]

Yes. My XXIII did not have the additional or backup propel blow tank.

[subkraft]

Thanks to all for your interest and responses. I'm overseas at the moment, so project on hold for a few weeks.

A couple of thoughts.....I'm not claiming any originality for the system, making it work using a set of standard 3D printed parts is the object of it for me. I was trying to avoid using a mechanical snorkel valve due concerns about size and jamming. Propel backup not an option for me, gas not available....or only available as airbrush propellant at a price that translates in dollars per dive.

Will certainly post follow up when I get back to the workshop.