Skipjack 1/72

[Albion]

We all hate the water you have , you know that dont you :)

[greenman407]

Hey! I thought this thread was about the Scamper?
Im heading back to Clearwater on Friday for some more testing. Until then....................

[greenman407]

Thanks Guys. I am really happy that I was wrong about a porpoising problem that I thought I might have. If you dont get the center of balance right, your boat will porpoise up and down at high speed. If you are not looking to go fast, you dont have a thing to worry about. In my Albacore build, I had such a problem:http://forum.sub-driver.com/showthread.php?824-Albacore As I was building this boat, Dave told me right where to locate the Subdriver, front to rear. It would seem that it was dead on as I was hauling Butt yesterday with it and there was absolutely no tendancy at all to porpoise.http://forum.sub-driver.com/showthre...core-continued
Right now if you take a string and cradle the hull with everything in place and ready for the water, it balances about an 1&1/4" in front of the hull mid-seam. Which is behind the sail.
Also I am pleased that I dont have a depth keeping problem like I had with the Albacore. You see, the Albacore now has two motors and two gearboxes and two propellors. Apparently there was just too much vibration to dial out and it was affecting the ADF too much, which was giving the highly sensative X-tail controls with their electronic mixer, too much jitter. What I ended up doing was moving the ADF up into the front battery compartment to try to escape those vibrations. When that didnt prove to be enough, I mounted the ADF to a thick piece of sheet plastic and then wrapped the plastic sheet in bubble wrap. The plastic ADF mounting board sits on top of the NIMH pack with a barrier of bubble wrap in between, effectively isolating those vibrations. You can see the X-tail stern here in these pictures. Now, the Albacore flies like the wind, like a thoroughbred straining at the starting gate, awaiting the bell. Another thing I like about it is the way it leans and banks into the turns. Very controlled and magical. Ill push the Scamper and see how she does and where that big sail will cause it to lose control.
The Xtail gives extreme manueverability. Itll go straight up while spinning on its axis, howling its way to shallower waters and then dive straight down like a Banshee, until you lose your nerve and haul back on the stick like a fighter pilot trying to get an ME 109 off his back. Great fun! Of course you need deep clear water to do this. At any rate, part of the Skipjacks, or should I say the Scampers success in this is that its not an X-tail. Therefore, since its control surfaces are not 1/4 of the Albacores, its not so sensitive to jittering of the stern planes. Even so I want to keep them under control so that it doesnt develop into a problem. Like using the first hole on the servo horn closest to the mounting screw or no more than the second hole. Setting the ADF on the least sensitive setting.

[crazygary]

Great looking electronics setup, Mark!!

Really clean and efficient looking!! Sweet!!

[Sublime]

Your Skip Jack is a pretty boat.

Note to self... Before testing my first model sub, call my lawnmower repair guy and inquire about "blade sharpening".

[greenman407]

I think that this must be one of those trick questions where your wrong no matter what you say.

[Slats]

Mark, with all that pubic hair wrapped around the prop can we call the boat the USS Growler?????

J

[He Who Shall Not Be Named]

Once you get a bit more stick-time under your belt with this ride, you'll find the sail planes to be most useful at depth keeping.

Good show!

M

[greenman407]

Yes, thats my lawn mower. I wouldnt have this problem if I was content to putts around on the surface or just under the waves at creeping speed. This pond has a few underwater mountains.....if ya know what I mean.

[trout]

Mark,
I am learning from you. I put the leveler all the way out at the end of the servo arm. So that it does not need to move as much for correction therefore a quicker response. Look forward to your test results. You bring up a good point about twitching too!

After a few more passes with your sub and the area will be weed free. That is an impressive collection.

Congratulations on the good run!

[greenman407]

As you can see I went dredging the bottom again. My shrink sleeve system on the rudder worked well as it didnt become disengaged. Because the sub is still in its grey extruded original colors, visibility is pretty good. Once its painted , black water will soak it up.
So far I am very pleased with her. More to come.

[greenman407]

Good as my Word. Today, I headed back to Clearwater, even though its overcast. To really wring this sub out as far as its capabilitys are concerned I need bright sun , so that I can see down into the water, to see obstacles and dramatic changes in depth. When I feel confident in these things we can fully open it up.
First of all I was quite surprised at its submerged turning radius. Its quite good. I dont have a floating tape measure but I would estimate a slow speed submerged turning radius of 3 ft. Thats because the whole rudder turns ,not just part of it as with some other subs. Using the first(least sensitive) setting on the ADF and using the first hole on the servo arm, to try to reduce the flutter that the ADF generates in the stern planes due to picking up motor vibrations, it produced quite acceptable results. Running at periscope depth or below , it was stable. I opened it up to 3/4 throttle and was quite pleased at its speed. Looks like its going to give my Albacore(mod) a run for its money. When water visibility is better , well let her go all the way. The next step will be to increase the throw of the stern planes and see if it has a negative affect on high speed driveability.
However, I must say that I see no good use for the sail planes. If your moving along with 1/2" of sail sticking out of the water but maintaining that depth, and try to use the sail planes to coax her under, it wont work. It just increases turbulance around the sail. However, if you are under and engage the sail planes, it will push you up on the surface. But, what good is that? If you are under and put the sail planes to a downward position, it will give the sub a more downward angle but it doesnt change the subs depth. So far as I can see, I can do everything I need using the stern planes only.

[greenman407]

Well...........................Its cold outside today, sea state 6, wind state 5. I think tomorrow will be a better day.

[He Who Shall Not Be Named]

Wow! Keep at it, Mark!

David

[greenman407]

Also, in the process of trolling the bottom, the dual magnets for the rudders got jarred loose. And.....would not reattach. So, I found a piece of heavy walled shrink tube that fits just perfect, without shrinking it. Itll give a nice little tunnel to keep the rods from dis-engaging and falling down into the bilge. Just toggle the control back and forth and it should reacquire. At least it better. After the rudder came loose and was stuck in maximum deflection starboard, it took some doing to coax it closer to shore. Anyway, I went thru the ADF setup procedure as well as zero bubble. Ill have it back at the pond tomorrow for another stab at it.While I was at it I put a notch in the endcap and the Lexan tube to help me align the thing when I put it back together.