A Report to the Cabal:
The plan was to get the model trimmed out in the kiddy-pool yesterday morning and to have it to the lake for sea trials in the afternoon. Well ... didn't happen!
Of course, before I could stick the model into the water, the WTC had to be watertight and working reliably. And that just was not as easy as I assumed. You know ... I've made more WTC's than anyone on this planet! I should be pretty good at it ... right?
So, why in the hell did I have such a hard time getting this particular unit working right?! Why did it seem that with each step forward I took two steps back in readying the WTC-2.5/KAIRYU!?...
It was one of those days:
I could not dial the ADC-1 to null at any depth shallower than nine inches. Three inches deeper than the tip of the extended periscope on my KAIRYU model.
The ballast tank components fought me tooth-and-nail from the start: first, the restrictor tube leaked (cracked actually, for some reason K&S produces some of their tube seamless, and some not -- and of course I was using seamed tube which cracks during the crimping operation); then the vent valve refused to seat tightly; and the gas-saver linkage just refused to work right and took hours to set up right.
And, finally, with the WTC fully assembled ... only then ... do I discover that I had not
shimmed the spur gear shaft tight enough between its bearings! During a motor test
the spur gear shaft torque pin jumped out from under the spur gear. Necessitating
removal of the unit from the equipment rails, followed by a complete tear down so I
could shim the drive train tight enough between the bearings to keep the torque pin
centered on the spur gear. Then putting everything back together again for another
test.
And then two of my cast resin watertight seals decided to join in the festivities by
kicking me in the balls. Yup, they leaked, and had to be replaced.
Fuck! Would this series of adjustments, fixes, and alterations never cease!?
Well, finally, after eating up the whole day, the damn WTC was working good enough
so I could drag the poor model off to the pool.
Concurrent with the horrors occurring at such a rapid pace in the shop, Kevin McLeod
and I were blasting e-mails back and forth about the ADC-1 depth issue. You know
Kevin as the guy who's been doing that magnificent 1/96 OSCAR ll build,
chronicled over at the Subcommittee site. Here's the URL, it's a must-see:
Anyway ... Kevin's an electronic Engineer and gave me some ideas on how to fool the circuit into nulling out at a shallower depth (to suite the specific periscope depth of my 1/16 KAIRYU model) than the factory (Skip's kitchen table) setting, which is too deep for my needs.
Got off the phone with Kevin last night, but before doing so, we agreed to put this problem aside as we both attended to other projects that have to be ready for the SubRegatta: His OSCAR has to be completed, and I have other turnkey jobs to get done as well. I can operate the KAIRYU just fine without the ADC-1. So, right now the ADC-1 is aboard, but not hooked up to the servo and receiver. Damit!
So, late afternoon yesterday, with the sun on the horizon, the WTC-2.5/KAIRYU cylinder beaten into submission, I began plunked it into the hull and began trimming the submarine in the front yard kiddi-pool.
Whew!
Initial in-water trimming started with several ounces of fixed lead weight bolted to the inside bottom of the hull -- most of that positioned well into the bow to get the longitudinal center of gravity where I wanted it: smack in the center of the WTC's ballast tank.
The first trimming trials were done with the WTC de-energized and the ballast tank vent valve open -- you initially trim the model in submerged mode, only after you get it to a nearly neutrally buoyant state -- the tip of the sail sticking into the air and the hull at a near zero bubble angle submerged -- do you empty the ballast tank and adjust foam location (above or below waterline, and fore or aft) to get the model submarine to sit at the same waterline as the prototype in surface trim.
Initially rubber bands on the outside of the hull secured hunks of foam to the hull --Once the foam amount and location had been determined through in-water tests, the model was taken inside, the foam cut up and glued within the hull, occupying the annular space between WTC and inner hull.
With nearly a pound of fixed lead weight serving as stabilizing ballast deep down in the lower hull, I needed to add some countering floatation foam high in the hull to produce the buoyancy needed to overcome the added weight of the model. After the initial trial in the kiddy-pool with hunks rubber banded foam secured to the outside of the hull, I took the model back into the shop, cut up and sanded the foam into pieces that would fit the annular space between WTC and hull, and adhered them in place with RTV silicon adhesive.
With the majority of fixed lead weight and buoyant foam in place I got to the 'fine tuning' of the models static trim. Here I'm sliding a little hunk of lead back and forth on the after deck to get the boat to float (in submerged trim) with a zero hull angle. Note that a small portion of the sail projects into the air in submerged trim.
Later, after 'sea trials' at Lake Trashmore, the countersunk fasteners used to hold the lead weights will be filled with Evercoat Metal Glaze, and those areas filed and sanded flush. Then the paint job and weathering.
Once happy with the longitudinal trim, everything goes back to the shop where the lead weights (there are three of them) are is drilled and tapped, two holes drilled into the bottom of the hull under where I determined the weights should be, and the weights secured into the bottom of the hull by running two 2-56 screws up through the holes in the hull and into the tapped holes in the weights.
Several trips to the pool later and I had a model that sat with only one inch of the sail sticking into the air and the boat on an even keel. Time to energize the WTC, turn on the transmitter, and check the boats surface trim.
Got an e-mail from Skip Asay, the originator of SubTech and designer of the ADC-1. He's going to give me some pointers on how to get the thing to hold the model to a shallower depth. That's the last hurdle on this project: getting the ADC-1 modified to hold the model at periscope depth. In the interim there are plenty of other cosmetic things yet to do on this model -- SubRegatta is only three weeks away and I have the usual production work and some turnkey jobs to attend to. Going to be a very busy month!