today's work

[Ken_NJ]

Thanks David for the regatta synopses. Always nice to meet up with everyone. Feels like seeing long time friends every time we meet. Would be nice to see everyone more than once a year.

Have a blast with the new 'kit'!

[QuarterMaster]

The Prize. A French ship? Just kidding.

From the Far side of the World.

NO....

Dave will custom build the winner an operational RC Model of Robur's "The Albatross" so you can become "Master of the World".
Vincent Price not included, some assembly required.

[He Who Shall Not Be Named]

REPAIRING A LEAKING MOTOR-BULKHEAD

But first, a little background.

Many moons ago Gary Kerr, who worked as lead-man on several Moebius Models kits, designed the definitive SEAVIEW model kit. That effort first centered around the 'TV version' of the submarine; a later release was of the 'movie' version.

Though these injection formed polystyrene plastic kits are intended for static display only, I and others have converted them for r/c operation.



The Caswell company, during a ten year span, employed D&E Miniatures (our business) to head development and production of items for the r/c submarine market. One such effort was a SubDriver (proprietary name given to a removable water tight cylinder) and 'fittings kit', to convert the Moebius plastic model kit into a practical, well running r/c model submarine.

The SEAVIEW SubDriver (SD) – unique in that it featured an exceptionally large ballast tank – had to float the surfaced fictional submarine at a ridiculously high freeboard; and housed two motors to drive pump-jets fixed within the propulsion tubes at the models stern.

In support of the SD and fittings kits we authored articles and videos which described how to convert the Moebius kit, through the incorporation of our products as well as how to gain easy access to the hulls interior by making the superstructure removable.

The SD was suitable for both the TV and movie versions of the SEAVIEW. However, as there are significant differences between the bow and sail of the two versions of this science fiction submarine, we were compelled to produce two versions of the fittings kit.

Demonstrating this: the picture below shows the movie SEAVIEW SD and fittings kit. This fittings kit has no provision to make the bow planes practical. On the other hand, the movie version fittings kit contained conversion parts to make the bow planes practical. (you can see what an ugly arrangement practical bow planes were below, and the two pictures that conclude this article).



Practical bow planes on this submarine look terrible and were found to be of limited utility in the water. As these control surfaces were so tightly nested into the tips of the SEAVIEW's strakes they become subject to turbulence that blanketed them from rational water flow, reducing those control surfaces effectiveness. And once they deflect in operation... THEY LOOK AWFUL!






We placed an emphasis on providing functional control surfaces, and efficient pump-jet propulsors – and to render those items to scale with the SEAVIEW; no over-sized control surfaces or out-of-place running gear. The last thing we wanted to do was corrupt Gary Kerr's excellent work of capturing the 'look' of Admiral Nelson's iconic submarine.

However, and these were necessities of function, departures from scale included opening up the pump-jet intakes in the propulsion tubes ahead of the internally mounted pump-jets; punching flood-drain holes either side of the central keel; and inclusion of a set of guide-vanes within the propulsion tube nozzles.

Those well hidden guide-vanes produce a pitch-up moment to the submerged submarine when thrusting ahead, needed to counter-act the pitch-down moment produced by the shovel shaped bow.









As the pump-jets are fixed within the narrow confines of the propulsion tubes, a means of easily making up the intermediate drive shafts that inter-connect the SubDriver motor shaft to the rotor-shaft of a pump-jet and are inaccessible to fat fingers. The solution took the form of spring-loaded, telescoping intermediate drive shafts.

Note that there is very little room near the stern, and the long reach the intermediate drive shafts have to make to reach the rotor shafts within the pump-jet duct.

Once seated onto the lower hull indexing pin the SD and motor coupler can not be moved to engage the 'dog bone' at the forward end of each intermediate drive shaft. The spring loaded intermediate drive shaft itself moves axially slightly to permit engagement of its dog-bone to the SD's coupler.



A SEAVIEW intermediate drive shaft is a unique affair, comprises two lengths of square brass tube, of varied diameter, one sliding within the other. Square to prevent rotation of one tube within the other. A compression spring, compressed against the after end of the dog-bone, its after end soldered to the after length of square tube. When the forward square tube is pushed into the after square tube – in ordere to insert its dog-bone into the motor coupler -- the spring is compressed and exerts the force needed to return the intermediate drive shaft to its correct length with the dog-bone nestled tightly within the coupler. Residual spring tension keeps the dog-bone engaged.

A length of flexible tube serves as a poor-mans universal joint between intermediate drive shaft and pump-jet rotor shaft.



One of my boating recently observed that his SEAVIEW motor-bulkhead was leaking and would I give him a hand with it.

When it arrived I dunked it into the test tank and ascertained that two of the pushrod seals and one of the two motor drive shaft seals were indeed leaking. The fix was simple: replace the bad seals with new. The cause of the leaks was time, and possibly the use of hydrocarbon based lubricants (natural buna rubber degrades with that class of oil). Silicon grease/oil is recommended for those type rubber elements.

Look closely at the six pushrod seals at the bottom of the picture. The dark green ones – just liberated from the motor-bulkhead – are original, and of the single O-ring type. The tan pushrod seals vary in that they have encapsulated within two O-rings. If you look closely you can just make out the dark O-rings through the semi-transparent tan resin.



The shaft seals are proper cup type rubber seals. The original pushrod seals employ a cylindrical cast resin body within which is encapsulated a single O-ring. Now I produce those seals with two O-rings, which greatly increases their longevity.

The picture below shows pushrod seals for both 1/8” and 1/16” diameter pushrods. In cut-away you can see how the O-ring projects slightly into the bore of the seal body to effect a watertight seal between the pushrod and seal body.



A couple of years ago, responding to complaints of leaking around our pushrod seals (I was observing the same problems with my own boats), I improved the tooling used to create these seals – increasing the number of O-rings from one to two.



The O-rings, each girdling a central brass rod mandrel, form the sealing rubber element within the cast resin body – here I gang as many as ten seals on a single length of cast resin rod.



The brass mandrel is pull out and the individual seal bodies liberated on the band saw.





Before making up the new motor-shaft seals I ran the motors to make sure they were working fine. They were, but I found one of the shafts to be off-center. Way... way too much 'wobble'. That had to be fixed first.

Securing the motor-bulkhead in the table-vice (very softly, taking care not to crush the motor cans) I check the degree of 'wobble' of each shaft with the dial-indicator. I've gotten pretty good at bending the shaft back into near perfect alignment with a tug here and a tug there with my fingers alone.

Once things were spinning reasonable true it came time to make up the new motor seals, and get this sucker out of the shop.

Note the three new-and-improved pushrod seals already RTV'ed within the motor-bulkheads body, sitting flush with the after face of the bulkhead.



The new motor bulkheads, and their conical support foundations were RTV'ed in place and presto-change o!... … fix y-poo!

The Good, The Bad and the Ugly!



A dunking in the test tank to check for leaks. None! And off to my pal went his repaired and tested SEAVIEW SubDriver motor-bulkhead. Now, with his mighty SEAVIEW back in commission he can rejoin the task of ridding his nearby lake or pool of those nasty Aqua-men, ghosts, aliens, blazing Van Allen belts, evil world-take-over cabals, mad-scientists, and Lobster-men.

You're Welcome!









Some bonus material for you: One of my assembled Moebius SEAVIEW kits in the water, as well as video footage taken from inside the bow, looking through the 'glass' windows.

https://youtu.be/CxfA5d2L0BA

David

[redboat219]

Thank you for posting photos of those fixed guide vanes.

Was looking over photos of your fittings kit and was initially wondering why were there 2 smaller elevators. I then remembered you mentioning the need for fixed vanes to counter the bow down effect but could find any photos of them in place.

What's their angle of deflection?

Pity you ceased producing fitting kits for the Seaview. Just got my hand on a Moebius kit. Just need PJ and stern fiitings.

[He Who Shall Not Be Named]

Thank you for posting photos of those fixed guide vanes.

Was looking over photos of your fittings kit and was initially wondering why were there 2 smaller elevators. I then remembered you mentioning the need for fixed vanes to counter the bow down effect but could find any photos of them in place.

What's their angle of deflection?

Pity you ceased producing fitting kits for the Seaview. Just got my hand on a Moebius kit. Just need PJ and stern fiitings.

about five-degrees at the trailing edge. Bob has all the masters and tooling now.

David

[redboat219]

Thanks.

Would it matter if the PJ stators are straight ?
I got this idea for a homebrew PJ using some odds and ends from another hobby.

[He Who Shall Not Be Named]

Thanks.

Would it matter if the PJ stators are straight ?
I got this idea for a homebrew PJ using some odds and ends from another hobby.

yes.........................

[redboat219]

yes.........................

Yes good or yes bad?

[He Who Shall Not Be Named]

Yes good or yes bad?

Yes. It matters.

[Das Boot]

NO....

Dave will custom build the winner an operational RC Model of Robur's "The Albatross" so you can become "Master of the World".
Vincent Price not included, some assembly required.

That was a great movie.

[trout]

David, Thank you for the explanation on the endocarp repair. You mention petroleum on the o-rings, is that what you found?

[Das Boot]

Too bad no one makes the kits for the Seaview rc anymore.

[He Who Shall Not Be Named]

David, Thank you for the explanation on the endocarp repair. You mention petroleum on the o-rings, is that what you found?

Very minor leaking from one of the three pushrod seals, and significant leaking from one of the shaft seals. As a matter of course, I replaced all seals. Tested and there were no leaks to the repaired motor-bulkhead.

For long service life of Buno rubber elements, I advocate silicon oil/grease. Over time hydrocarbon lubricants harden and break down the rubber.

David

[rwtdiver]

Hi David,

Just a short note to you!

Well done on our 6-3-2023 Dive Tribe! I missed the meeting, but I went to the re-play. Your information was very good, and your presentation was excellent!

Rob
"Firemen can stand the heat"

[He Who Shall Not Be Named]

Hi David,

Just a short note to you!

Well done on our 6-3-2023 Dive Tribe! I missed the meeting, but I went to the re-play. Your information was very good, and your presentation was excellent!

Rob
"Firemen can stand the heat"

Thanks, Rob. I had plenty of time to prepare the 'soldering' segment, but only a day to cobble together the 'how to salvage a model submarine' talk, so that half of the program was a bit ragged, but I think I got the main points across. And kudos to Bob for seamlessly sliding those pictures in during the talks -- big aids as I described process and pointed out details. Pictures ARE worth thousands of words.

David