Another Gato for the pacific fleet

[trout]

Alec,
You will have fun! I say this not with some premonition, but from my experience. Please take lots of photos. Be safe my friend! Look forward to your post mission report.
Peace,
tom

[alad61]

Thanks Tom,

Sorry all for the late response. Life kind of got in the way when we got home from the trip so its taken a bit to edit and upload the only video I got. Well except for a horrid roads trip there and back it went well. I will be honest and say it was a little disappointing in respects of the pool. It was much smaller and shallower than the one at Gosford. As a result I didn't think that any sub came away without needing paint on their bottom bow area. The plus side was talking and meeting with other rc submariners and finally meeting John Slater. Who by the way knows how to put together an rc sub, but we knew that anyway. But I did enjoy the week end, my day long visit to the Australian War memorial an Museum on the Easter Monday in Canberra, our detour to Sydney and seeing the Lion King on stage there before the drive home.

The Gato performed well enough for its first official run out of the tub. I reckon I need to get it lower in the water when I flood the ballast. At the moment the forward gun deck on the tower is just at decks awash and to get it to dive I had to keep the throttle set to 60% which gives it a scale speed of about 35 to 40 knots. It's almost like driving a dynamic diver... With where I have it trimmed I found it was still struggling to get the boat high enough on blowing the tank with the sas to get the float to fall so that it will draw air through the float valve. I'm thinking I need to modify how the valve sits so that I can get a bit more height by raising the float base a few millimeters and filing the opening further back so the foam sits closer to the valve... any thoughts David? However by the middle of the second day I mastered it enough to get a good fun run out of it. These boats at more than 60% throttle are very responsive on the planes so care is needed. Because of the size of the pool it was hard to get a good long PD run because you soon need to turn so that pushes the bow up with a full rudder and the turning circle is not like the skipjack so there were several emergency all backs and three point turns need to navigate the waters at times. The little 1800Mh 7.4 lipo i am using gave me a solid 40 minutes of play time before the fail safe kicked in and blew the ballast when it detected the low battery power

My Skipjack was as usual a great deal of fun to sail as was the Akula till I bumped the wall a bit hard and broke the front mounting clip for holding on the top hull. My Robbe Seawolf zipped around till the rear o-ring failed and it took in water but not enough to wet any electrics. Ahh the joys of RC submarines LOL

I didn't get to many videos or pictures to offer here as I got a little carried away running my boats but what I did take are here...

Jim's Seawolf as result of kissing the wall a little to passionately

There were three Skipjacks about four type XXIII's a couple of TT Nepunes, many variants of German u-boats from kits to scratch builds. Dr Pat brought along his big U-boat and there was an Engle 212. There were some Russian nukes and British one as well. Which at times made for a rather crowded pool!!

[HvyCGN9]

Great photo's Alec!!

Cheers Bruce

[He Who Shall Not Be Named]

Yeah. Just add fixed ballast weight till the submerged waterline is even with the base of the shears and you're good. Thanks for sharing!

Did you remove all of that tank-top plastic before attaching the superstructure? If not that may be why you don't have enough ballast water aboard to achieve the designed surfaced waterline and submerged trim.

M

[trout]

Looks great Alec, like you mentioned a bit lower in the water will mean less forward motion to bring it under. That sure is one pretty boat and you commanded it well. We'll done.

[alad61]

Thanks guys,

David I am pretty confident that I removed as much of the styrene as I could and still keep good integrity and the weight of my lead is equal to both the lost styrene and added extra for the conning tower to counter the listing that occurred when blowing the ballast statically. Additional thinking last night has brought me to the decision of stripping out most of the lead and all the foam and starting the trim again.

This afternoon I took out most of the lead and opened the opening under the tower so the valve float has a bit more pivot travel. Tomorrow I'll fill the tub again and re trim the boat with a differant foam. I think part of the problem was the foam I used was not as closed cell as it should have been and I maybe had too much of both lead and foam. I'll keep you posted.

[alad61]

David I basically did the reverse... I already had what I believed to be an overkill of lead and foam. So I took out just on 5 ounces of lead, which I reckon was almost half, and stripped out all the foam. Cut some new foam, filled the bath, aka test tub and spent the last 3 nights redoing the trim. Before that I cut out the SAS valve opening, turned the foam float around so that the thinner section under the hole for the pivot bar. This gave the float a few extra millimeters of pivot. Now as to the lead the majority sits under the ballast tank with some smaller pieces more forward and aft to get the sub at a level submerged trim. Because of the lighter battery I have most of the foam sits from the forward ballast bulkhead to aft over the props with some under the deck, again just to get the submerged trim level. Now the boat sits much deeper so that just the scopes and exposed framework is at water level. This should let me dial back the forward throttle to 50% for a much easier down bubble on the planes to run a pd. I also think my underwater turning was inhibited by all the lead spread throughout the hull and the volume of foam needed to counter it, but I might be wrong... A good open water run will be the test. In short less ballast and foam gave me a better submerged trim so the saying that less is more actually does mean something...

[He Who Shall Not Be Named]

I wont' argue with success. OK, the boat is almost neutrally buoyant in submerged trim. Now: can the boat achieve designed waterline in surfaced trim?

M

[trout]

Centralizing the weight will make your sub turn better. How is the tipping as it surfaces? Really interesting what you are doing, so please show photos!
Peace,
tom

[alad61]

David the surface trim has the boat sitting with the the top quarter of the rear torpedo tube above the surface and then follow that with a straight line to the bow. It's about an eighth of an inch hight than I would like but help I can live with it.

Tom your right I should have taken pictures but I was under pressure from the wife to get it finished and cleaned up for our dinner party this weekend.

[He Who Shall Not Be Named]

The freeboard is too high? Good. All you have to do is move some of the foam at the longitudinal c.g. above the waterline and you're in business.

Like Tom, I want a report on how the boat heels when surfacing now that you've reduced the metacentric height.

M

[alad61]

David just so I am clear... At the moment it sits with the water lapping along the large drain/limber holes at the bow and then parallel along the hull much the same as this sub in the link below.

http://en.wikipedia.org/wiki/File:USS_Balao_SS-285.jpg

So when I said about a qtr of the rear tube I was referring to the top one and my quarter was in reference to the tube frame profile not the actual tube portal itself. As for the heeling over it heels a little to port when filling the ballast but it helps hard to starboard when the deck broached above the surface. So I need to move some foam from port to starboard to settle that but I have been banned from the 'test' tub till after the weekend...