From: DMeriman@aol.com To: undisclosed-recipients:;
Subject: R/C"ing the Revell 1/72 GATO Class Static Submarine Kit,
Part-13 Date: Tuesday, January 02, 2007 12:38:19 AM Attachments: ygpDDA0.jpg
A Report to the Cabal:
Time to get the Revell 1/72 GATO kits rudder and stern planes to wag in a convincing manner. Testifying to this kits fidelity to scale is the fact that those control surface parts are complete, right down to practical, operating shafts! These on a model that is for static display only, not intended for r/c use. As Crazy Ivan pointed out you can use the rudder and its attached operating shaft with little modification as he did on his r/ c'ed GATO. However, on my kit I chose to reduce the rudder shaft diameter substantially, so snipped off the kit shaft and drilled a long running vertical channel within the rudder to accept a thin 1/16" brass rod. This done to make room for a possible later four-tube launcher installation.
I also (finally) glued the two propeller shaft strut bearings to the hull after validating that all the elements of the running gear (strut bearings, stern tubes, thrust bearings, intermediate drive shafts and their associated couplers) fit and spun with no interference and little drag.
It was a simple task to convert the rudder and stern planes into practical, operating surfaces. Here you see the finished results of that effort. Also, you see that I've glued the strut bearing foundations to the hull and have test fit the two new propeller masters to some temporary brass shafts. I will always have these shafts in place --they greatly strengthen the union between strut bearings and hull, without the shaft (or 1/8" brass rod stand-ins, like you see here) it's just too easy to break these delicate items. One more reason to get those rope-guards on the hull as soon as possible!
Looking through the upper starboard torpedo tube opening you can make out the silver white metal bell crank (control horn) hanging off the vertically running rudder operating shaft.
A few days ago Mike Keating, over at the SC site, mentioned that he did not like the look of the stern planes. I have to agree, I think I'll taper them near the tips, that should get them to look a bit more like prototype.
I chopped off the very thick plastic operating shaft from the rudder, drilled a 1/16" diameter vertical hole through the rudder (denoted by the two parallel inked lines); tightened up the bearing hole in the bottom of the hull for the smaller operating shaft; punched another a hole in the after skeg half to pass the shaft; and installed a journal bearing within the top of the hull. You can see the rudder operating shaft running the entire height of the models interior.
I went to the smaller operating shaft to make room for a possible torpedo tube nest later.
The set-screw in the side of the rudder is a temporary measure. Later, as I complete the control surface linkage job, I'll glue the operating shaft permanently into the rudder and I can dispense with the set-screw and fill the hole.
When I snipped off the fat operating shaft from the rudder, I used a piece of it in the lathe to form a journal bearing to fit the big hole in the bottom of the hull. Here I'm boring out a 1/16" hole within that bearing. The hole will permit a low slop fit to the rudder operating shaft.
Note the small hole in the bottom of the rudder -- the bore extends vertically through the entire rudder, permitting me to put the rudder in place, run the operating shaft up through the rudder and on into the stern of the hull, stopped, the bell crank is inserted, and the shaft run up till its upper end fits into the journal bearing set into the top of the hull.
George "Crazy Ivan" Protchenko, came up with the outstanding idea of making the bottom skeg piece on this kit removable. This modification permits accessing the stern planes and rudder for removal, adjustment, and repair. Initially I was going to use the entire skeg piece like this, with no other modification than drilling and countersinking holes for the two 2-56 machine screws. However, I later split this kit part vertically so that the forward end of the skeg piece, with the two struts, could be permanently welded to the hulls skeg -- this needing to be done to insure I had a very sound attachment system between strut bearing foundation and hull.
The only survivor of the big plastic operating shaft from the plastic rudder part is this short length of material that was bored out with a 1/16" diameter hole. This will be glued into the big hole at the bottom of the hull forming the journal/support bearing for the rudder. Note that in the removable lower skeg piece there is a slight aft projection that has a small hole in it -- this to engage the rudder operating shaft, this constitutes the bottom bearing off of which the rudder is suspended from the hull.
Looking within the hull at a trial fit of the rudder operating linkage. You can clearly make out the vertically running rudder operating shaft, when it is slipped in. Note how the bell crank is suspended on the operating shaft between upper and lower bearing. A 1/16" diameter brass rod serves as the pushrod that connects the rudder to the WTC pushrod.
Later, I connected up the stern planes to a piece of 1/16" brass rod which formed that control surfaces bell crank. Here you see the completed linkages of both rudder and stern planes as they are arranged within the stern of the Revell 1/72 GATO kit.
Next installment I'll go into more detail on how the stern planes are hooked up and accessed.
I sawed the skeg piece into a forward and after half. The forward half, seen here, is about to be permanently welded to the hulls skeg -- this to achieve the maximum strength at the strut to hull union. Before applying the solvent cement to the union I took care to scrape and sand away primer off the contact points -- you need to insure that only styrene plastic makes contact with styrene plastic before applying the solvent cement.
Temporarily using the forward machine screw to hold the skeg piece to the hull I applied a liberal amount of the cohesive. This very thin liquid quickly finds its way onto the surfaces of the parts and quickly melts the plastic and causes a fusion between the two substrates until a weld is achieved, obliterating the seam and making the assembly a single unit. That's what a good weld does, it makes two or more parts into one.
Don't confuse cohesion (welding or fusion) with adhesion. Adhesion is the sticking of pieces together by the introduction of a third constituent that becomes part of the union.
After giving the skeg piece to hull weld two hours to set up I then inserted the two strut bearing foundations -- the inboard side of each strut bearing foundation receiving the end of a skeg strut, and a strut projecting from each strut bearing foundation fits into a slot molded within the side of the hull. I then ran a length of 1/8" brass rod through them, checked the strut bearing foundations for fit and that the shafts would turn without binding, then applied Ambroid ProWeld cement to fuse the struts in place permanently.
You see here the forward half of the skeg piece, permanently fused to the hull. The single machine screw used during alignment and to hold things together during the welding operation will be removed and the hole filled and filed to contour. Just for fun I stuck the two propeller masters on the shafts to see how things look. Not bad!