Skipjack 1/72

[greenman407]

SUCCESS!! With the new snorkel valve installed(not that there was anything wrong with the original one)and the brass tube connection sealed, I went thru 6 full submerge and surface cycles using the SAS pump and system. There were two small drops of water in the sub-driver rear dryspace. I think I can live with that!
One thing that I noticed and had to deal with is that the inside dimension of the inside of the sail may vary. Therefore, that has a direct bearing on whether or not the snorkle valve will seal or not everytime. Thats because the foam part of the valve, if there is too much space, between the walls of the sail and the foam body, it will allow the foam to get out of alignment where the rubber seal touches the brass upper tube. If the foam has too much room, there is nothing to hold it straight and it will touch the rubber pad, slightly off of the edge of it, allowing water to enter. Observe the pictures. So what I have done is build up the inside walls with "Plastruct" channel CAed to the wall. Great care must be taken because if you arnt careful you can cause to little space to be available and cause the valve to stick, and therefore.........leak.

[greenman407]

Also, when I removed the old snorkle valve, I noticed that it was binding because there are two brass tubes that slide within each other ,within the foam. I believe that corrosion can build up on it and cause resistance to the floats movement up and down. Maybe dry graphite or some other product will be helpful.

[He Who Shall Not Be Named]

Good, solid evaluation of the snorkel mechanism problem. I will re-examine the mechanism and will attempt to correct the fit problems you observed. Good work, Mark.

M

[Scott T]

What if the float was a cylinder instead of a recatgular shape? Put a washer shaped rubber
seal pad on the top. If it rotates it always has a sealing surface and should be the same
distance from the wall. Use a plastic straw for the sliding surface in the middle of the float????

[He Who Shall Not Be Named]

What if the float was a cylinder instead of a recatgular shape? Put a washer shaped rubber
seal pad on the top. If it rotates it always has a sealing surface and should be the same
distance from the wall. Use a plastic straw for the sliding surface in the middle of the float????

I investigated that but wound up with a ring-shaped rubber element production problem, specifically: labor intensive. Time is money.

The solution is to tighten up the gap tolerance between square sided float and inside surfaces of the sail. And a switch from closed-cell polystyrene to a slightly denser closed cell polyurethane (Renshape) float. I've also gone to a larger diameter rubber element disc size to cover what little torsional displacement presented by the float in relation to the induction nipple.

How timely. I'm making another production run of 1/72 SKIPJACK snorkel mechanisms today -- these changes in effect from now on.

Good stuff, Scott.

M

[He Who Shall Not Be Named]

And here's what I came up with: the 'new' 1/72 SKIPJACK snorkel mechanism.



The original snorkel mechanism to the left, the new one to the right. Note that, as Mark suggested, the narrow loose fitting foam float can rotate too much resulting in misalignment between the induction nipple and rubber element -- a flooded induction line would result. Bad Ju-Ju!

The new snorkel float is a much lower aspect ratio. It's extended length meaning that there will be very little rotation between the float and induction nipple -- no flooding!



Note that the sides of the new float are in very close proximity to the inside of the sail, this coupled with the increased length of the float insures very slight rotational offset between induction nipple and rubber element -- no chance of flooding because the float wandered a bit within the sail.



Production of the new type 1/72 SKIPJACK snorkel mechanism.

M

[Slats]

Excellent and it kicks in much higher up the sail too.

J

[He Who Shall Not Be Named]

Excellent and it kicks in much higher up the sail too.

J

Good catch, John. I forgot to mention that the lower aspect ratio float (same displacement as the original) will open with less sail out of the water, venting the SD's interior before too much vacuum is created.

I count on you bum's to catch stuff that is not working right -- Mark's comments about the old 1/72 SKIPJACK snorkel float is a fine example. This is how the product is improved.

M

[alad61]

Ooh...ahh that looks nice. It also looks like it gives a bit more open head room around the induction nipple too :) David will it be available as parts so we can retro fit?

[He Who Shall Not Be Named]

Ooh...ahh that looks nice. It also looks like it gives a bit more open head room around the induction nipple too :) David will it be available as parts so we can retro fit?

You guys who want the up-grade: e-mail me with your address and needs. But, only if you've bought the SD that uses this thing -- this ain't a frig'n charity!

M

[alad61]

Doh!! John pipped my comment at the post... David you're right about mentioning stuff like that. Often I just get on with tweaking and don't even consider it being someone else's issue.

[alad61]

You guys who want the up-grade: e-mail me with your address and needs. But, only if you've bought the SD that uses this thing -- this ain't a frig'n charity!

M

email sent...

[He Who Shall Not Be Named]

Doh!! John pipped my comment at the post... David you're right about mentioning stuff like that. Often I just get on with tweaking and don't even consider it being someone else's issue.

... and use the sharp knife. I need to know all the gory details!

Tom, Al and Andy are masters at critique writing, So's John. Mark's learning how. The rest of you pussies -- what's the deal?! ... you must be scared I'll jump out of your monitor and choke you if you hit me with some constructive criticism. Loosen up, guys: you see something wrong, say so!

M

[HvyCGN9]

email sent mate!!

I know alot about Surface warship stuff.....I also know that I know Sweet F@#$ all about sub techie stuff!! Which is why I like these forums havin two or three others building same hull gives great insight into setting one of these little monsters up.

Cheers Bruce

[HvyCGN9]

A Question! How many of these hull locating pins as seen in the pic are ground off??



Cheers Bruce