Skipjack 1/72

[He Who Shall Not Be Named]

As to the device tray flexing: insure that your pushrods are not binding -- take care to bend the forward ends to make up to the servo bell-cranks so that the pushrods are in the seals 'sweet-spot'. And lubricate the pushrods where they pass through the seals with silicon grease.

Looking good, Mark.

M

[greenman407]

Installed double magnets and a couple of sleeves to prevent unwanted movement during separation. Ill also move the pushrod engagement position on the servo horn from the third hole into the forth hole to see if that helps dial out some of the delay of movement of the planes when prompted. I can always dial back on the endpoints in the radio to prevent too much range of movement. Another thing that I noticed was that the aluminum tray that all the servos and stuff are attached to also has a tendency to flex and move when the servos operate. This will call for installing a gusset or two to stop that sort of thing.

[greenman407]

Made this quick little bracket and CAed it in place. It helps a little but, I think that the bellcrank system that Dave used on the Gato Subdriver would be more suitable. To describe what Im talking about is that you move your stick three or 4 detents before it starts to move and then it jumps and catches up. Then you move about three or 4 detents more before it starts to move and then it jumps. Under the pressure of the water streaming over it I would think that it would be much worse. Not good for fine tuning periscope depth.

[greenman407]

Man! I hit the length of the rod and adjustments perfect the first time. No need to adjust............except there is flex in the sail planes. The culprit is the flexing of the brass pushrod coming out of the subdriver and the bent double 90 degree extension that attaches to the magnets. For strength, these 1/16" pushrods arnt as strong as the 1/8" ones of old. Well, no matter. We will work with it. Im going to make a bracket as I said before and mount it to the engine bulkhead leading edge to help restrict some of that flex.

[greenman407]

The length worked out perfect. I can already tell you that Ill have to use two magnets. I can grab the sail planes and with little effort , I can break the magnet loose. With High Speed water breaking over them, I dont want it to disengage. However, the sail planes are not critical to operation as most of the control, I believe, will rest with the stern planes. Sail planes are just the icing on the cake. But, I still dont want them coming loose.

[greenman407]

I have elected to use this ready made pushrod cable for aircraft, just cut to length to suit you. If it doesnt work, ill just take it out. No harm done. I just tack CAed it in a couple of spots just off center to line up with my Klikon on the Subdriver. Notice that I used a brass short section as a holdown at the tail end. If I end up using dual magnets at this joint then I will add another one all the way back to better support the cable so that when you lift up the top hull to remove it, youll have no stress put on it.

[greenman407]

Here is Daves setup. I believe in this picture, he has yet to install any hold downs for it.

[greenman407]

How long should your pushrod assembly coming off the sail and extending back to connect up be? Easy! Carefully measure from the front lip of the seam where bottom hull joins top hull to the aft end of the sail magnet(do this at sail plane neutral position). Right that measurement down. You can use a small tri square to be accurate.
Then , measure from the lip of the seam on the bottom of the hull back to the inside of the motor bulkhead, looking thru the clear acrylic. On mine Im looking at close to 20&11/16". Then the Klikon is sticking forward of that by 7/16". That is at radio stick neutral. So subtracting the two gives us 20&1/4". Remember the number we got using the square? Subtract that and you have your distance, in this case 17&1/4". Thatll get us real close..end to end of control cable including magnets. If your using the clevis hookup that I am on the front then it would be to the rear of the drilled 1/8" hole in the clevis.Uh...........duh!(no emoticon available)

[greenman407]

This picture gives us a better idea how much room is available and where to set your pushrod. Really, for all intents and purposes, it couldnt be any better. Youve got very little play, and thats good. You almost cant go wrong by setting it close to the underside of the hull. As far as setting the length, youve got a lot of adjustment. If you use a threaded Klikon then there is adjustment there. You have two adjustments on your pushrod bracket where the pushrod exits the subdriver. If you use a threaded clevis at the sail, then you have adjustment there. Im thinking that upon assembly for operation that you would move the radio stick to the full up position and your sail set to the full dive position. After top hull is attached move radio lever to down position and sail plane to surface position. At that point your magnets will...."click". .....Uh....that is ...of course how I think its going to go.

[greenman407]

After installing the supplied and suggested sail pushrod end at the subdriver, I have mixed feelings. A good system to be sure, but Im afraid that when you go to remove the hull top section, there will be a tendency to bend the pushrod where it exits the subdriver as well as at the allen head bracket joint. Im proposing installing a hold down. Ill have to make one and install it with two small screws to the top edge of the motor bulkhead. Picture soon.

[greenman407]

Mini update here. To better secure the pushrod to the sail magnet, I borrowed some clevises from a airplane pushrod kit and drilled out,(ever so extremely carefully) the center of it to 1/8" ,to fit over the extended magnet, like thus. Also I am going to try using a Sullivan "Goldenrod". A nylon control cable. To prepare for the nylon control cable, there is a need to clean out a spot for it. Here you can see some "Dremel" work. Using the small drum sander attachment and "xacto" knife, to make a trough for it. The last shot shows how much room that you have for the control cable and its hookup at the tail end of the Subdriver location. Looks to be about 1/4"-5/16".

[greenman407]

Here we go with the pushrod install. Doesnt take much bending at all to get them to line up. If youll notice, following the suggestions of others, I have installed a piece of hose from the top of the safety valve and run it thru the deck and down into the bottom.

[greenman407]

Note the battery on the left. See how puffy it is compared to the new one on the right. Ive never used it. Ive charged it about 4 times without a balance charger and left it in my storage shed at 120 degree temperatures. I believe that this contributed to its demise. From now on Ill store it at work in cooler temperatures and store it at 50% charge or there abouts and will be balance charging only.

[greenman407]

With new LIPO in hand I thought I would share some info about these things. First youll note the 6400 Mah rating. If you move the decimal place 3 places to the left, that will give you your Amp Hour rating of 6.4 Amp Hours.

The 3S symbol denotes 3 cells adding up to 11.1 nominal volts. For safety sake, do not exceed 4.2 volts per cell nor go under 3.7 volts per cell.

Store your LIPOs at 30% to 50% capacity for longest life.

2 cell lipos should not go below 6.4 volts and 3 cells should not go below 9.6 volts.

The C rating is the batterys Mah rating divided by 1000.

1c charge rating is the safest, although some can be charged higher. Consult the paperwork that came with your battery.

In the picture you will note a 25C rating. Thats discharge rating. Do not exceed this.

71 WH is Watt hours. Thats determined by multiplying your Amp hours by Volts.

Do not exceed 115 degree Fahrenheit during charge.

Do not exceed 140 degree Fahrenheit during discharge.

[greenman407]

Hey! Who took away the emoticons. Without the emoticons how can I express my innermost feelings and relay my hidden emotions? Besides............they are cute.