Scale Ship Oscar 2

[greenman407]

Re: Scale Ship Oscar 2

Thanks for your help. I am using blue foam and all three subs that I have act the same way.

[Guest]

Re: Scale Ship Oscar 2

Ok, how much is really being compressed? it is 44 psi per every 100 ft, so 4.4 psi per every 10 ft and .44 psi per every foot (seawater, fresh is .43, pool water would be close to seawater because of the chlorine). You are saying this happens around 10" so the compression is roughly .37 psi, not very much. What kind of foam are you using? Seems to me that it could be an air trap problem and not a compression problem (or maybe a compression of air bubbles problem). Styrofoam cups have to be taken down several hundred feet to be compressed smaller then they started. I have several that were exposed to sea pressure in a torpedo tube near test depth and are the size of a shot glass. I also would look at the area that you are running, neutral bouyancy can be affected by other factors such as density of the water (salt/mineral/chemical content) and temperature of the water (warm water has less ability to support the boat, cold water will support better). I have many a time been on the way to periscope depth in the real thing and have crossed the gradient and either almost stalled out and had to pump to get up or have gotten too light and had to flood to avoid broaching the boat. The funny thing about bouyancy is it acts the same on a 7900 ton submarine or our little 10-15 lb boats I hope this helps a little.

Tim

As you say acheiving neutral bouyancy is no simple matter, it is quite a narrow band between postive and negative, doesnt matter if its big or small. It takes a lot of volume to get us down to only sail showing but then it all becomes tricky, and a small amount of additonal ballast or foam makes a big difference. To me it sounds this is a well trimmed boat.

[subicman]

Re: Scale Ship Oscar 2

ll three are acting the same, then i would have to agree with Albion and say they are well trimmed. It is probably the enviromental conditions in your area that is causing any inconsistancies.

Tim

[greenman407]

Re: Scale Ship Oscar 2

Saturday morning it was back in the pool for some more work. I have been trying to dial in the vent and ballast tank blow settings but its been difficult. For one thing it has a very large ballast tank that you want to fill with water. At present it is taking up to 4 mins. to get it under(too long). It seems that the servo mech. doesnt have enough throw, Ill keep working on it. While this was going on I got distracted with other business. When I returned I found that the sun had heated up the Propel that I had put into the copper tank in the Subdriver. From where I was I didnt here the bursting of the feed hose but I wish that I had. I dont think I will ever do that again. The funny thing about it was that I thought about the possibility of this happening as I was walking away from the sub but I dismissed it as not probable.


It also blew the hose loose from the schrader valve. I had some extra pieces of hose so I made the repairs that evening. All I had to do was take out the copper vessal, replace the hose , reapply the silicone to the attachment bolts and around the fill valve, insert and bolt it back up then reach up thru the large ballast flood holes with a pair of needle nose pliars and insert the schrader back into place and tighten it down.

[greenman407]

Re: Scale Ship Oscar 2

When I started out that morning I put the sub in the water without the top half of the hull so that I could better see what was going on. I noticed that there was a trail of bubbles coming from the endcap on the ballast tank. So I pulled it out of the water and sealed it up with silicone grease. Then I noticed electrolocyse(spell check doesnt work) in action. The positive wire hookup thumbscrew was giving off a lot of bubbles. It doesnt do that in the bath tub so it has to be the chlorine. Thats why the electrical conn. that are exposed to the water turn green. Then if I tilted the sub, then bubbles would excape from around the hole that I had drilled into the bottom of the ballast tank for the alighnment pin. After applying silicone grease to that it stopped. And finally I need to edit my earlier report on the snort system. It now takes 45 sec. to blow the ballast tank to surface trim.

[greenman407]

Re: Scale Ship Oscar 2

Ok! I recieved the props from Kevin Mcleod yesterday and what a fine looking set of props they are indeed!

You can see here the prop on the left(silver one) is from Kevin. The one on the right is the original one supplied by Scaleships. Kevin was nice enough to resize the holes to 5mm and he even installed a set of set screws in them. They have yet to be cleaned up, that will come later.
The new props measure 54mm in dia., an increase of 1mm, which is fine with me.


In this image you see the blade area of one verses the other. I am going to say that even though the blades are different shapes, Kevins props look like they have more blade area due to the fact that they are longer. I previously did a static pull test with my digital fish scale and will do the same with these props and note the difference. I am hoping for a thrust increase( I always want more).If I get an increase, thatll tell me that the motors are not overstressed since they are now producing more thrust. I will then need to watch the temperatures of the motors. Dave Merriman said that he is going to send me a set of gearboxes to increase the gear ratio to 9 to 1 up from the stock 3 to 1. We will then repeat the tests. Somewhere I have seen these stick on wafer thin thermometers that hold the highest reading. Perhaps something like that will reveal the temps of the motors.

[greenman407]

Re: Scale Ship Oscar 2

Since this is a model of the Kursk that I am building I am curious about the loss of the sub. I found this video series on youtube made by National Geographic in 5 parts. Each is about 10 mins. long and are extremely informative and well done. They are worth your time.
http://www.youtube.com/watch?v=Krdk-acA ... RWFUZ7DYDI
http://www.youtube.com/watch?v=2VQo_cbh ... re=related
http://www.youtube.com/watch?v=FTjuE5KM ... re=related
http://www.youtube.com/watch?v=f5R_tJDk ... re=related

http://www.youtube.com/watch?v=DYbZMB09 ... re=related

[greenman407]

Re: Scale Ship Oscar 2

Inquiring minds need to know. If the torpedo in number 4 tube exploded blowing off the hatch that leads outside and the inner hatch as well then why didnt the seawater rush in to the tube and extinguish the fire and at the same time flood the torpedo room??? Where is Columbo when you need him?

[greenman407]

Re: Scale Ship Oscar 2

Well I got the new props installed with red loctite and I drilled a hole into the shaft to recieve the set screws. So all thats ready to go. The next issue was the ballast tank. It was taking 4 mins.+ to flood it. Thats too long in my book. Adjusting the adjustments on the tank didnt help. So I made some mods. to the ballast tank that I believe will raise some eyebrows but will result in a faster flooding tank. I hope to test it this weekend.

[greenman407]

Re: Scale Ship Oscar 2




Here you can see( kinda fuzzy) the mods to the Subdriver ballast system. Because of the large volume of the ballast tank it was taking 4 mins plus to flood it down. To me it was clear that the problem resulted from the lack of throw or servo travel that was not allowing the vent to open wide enough. The servo that normally opens the vent is mounted to the inside wall of the ballast tank bulkhead. Because it is so close to the wall and because the motion of the servo is not linear, Dave has to slot the servo arm to keep from having the pushrod bind as it moves in and out. The consequence to the slotting is that it reduces the amount that the pushrod can move, thus the limited opening of the vent. This system works great on my other WTCs because they have smaller ballast tanks. So I installed one of my waterproffed servos on the inside wall of the ballast tank endcap and ran a long 5/32" square brass tube from the servo arm . On the one end I soldered a 1/16" brass rod to work the ballast tank mech. and penetrate the pushrod seal. On the other end I installed a quick disconnect. Also I had to lengthen the servo wires by soldering on a multiple conducter wire and sealed all the joints . Then I drilled a 3/16" hole in the ballast tank bulkhead to allow it to pass through into the dry space and sealed it well. Also the endcap that the servo mounts to was kind of a loose fit so I used vinyl electrical tape to seal the endcap on so that the force of the movement of the servo would not push the endcap off. I wanted to drill and install screws to keep it on but I was concerned about cracking the tube being that the holes would be so close to the end. Mounting the servo so far away from the ballast tank mech. and pushrod seal was done because it was the most convenient place and it would be out of the way and I wouldnt have to worry about any binding at the seal. Also at this time I removed the gas saver system. How does it work? So far so good!!!

[greenman407]

Re: Scale Ship Oscar 2

Also at this time I tested the propellors that I recieved from Kevin Mcleod. Using my trusty digital fish scale It registered a total of 12 ounces of pull against the scale...no more. As I increased the throttles I could hear the increase in RPM of the motors but the pull reduced. This I believe is due to the props( white metal) bending or flexing against the water. So the best thrust is produced at about half throttle. The sub ran great using these props and produced good scale like performance. However, since I am a speed freak from way back I will purchase another prop from scaleships as their brass props produce more thrust. So , using these props and my newly modified ballast system I braved the deep dark sub pond once again on Sunday!








Oh my goodness , what a wonderful ride! I will provide more details later today.

[greenman407]

Re: Scale Ship Oscar 2

Shoot! I thought that the Seaview was very scalelike in operation. This thing takes it to a whole new level for me! I was so impressed at the way she handled! Very stately, she supremely glided through the water as if nothing could stop her, NO FEAR! In the photos of the full size machine, take note of the way the water peels off the bow and flows along the sides in a ripple effect, as if to say ,I will yield to you for now but as soon as your stern passes I am going to flow back into my place. Well this is almost the exact picture , just minimized a little bit. Of course as predicted she turns like a pig! On the surface when the upper rudder is out of the water and not of any use , Im going to say that the turning radius is about 30 feet, thats a 60 foot diameter circle, not good. I will probably add some clear acrylic rudder extensions like some have done to tighten up the turning circle some. Its a good thing that I have independant control over the props so that I can use them to slew it around. With my ballast tank mods I can have her under the water in a minute and a half at this point. I gotta work on my crash dives! The forward dive planes being controlled by another of my waterproffed servos also works extremely well! With the ADF controlling the stern planes I have very fine control over periscope depth height. No more am I satisfied with just trying to keep her under, now I can split hairs with my depth control. When I purchased my Polk radio I had them install on the right stick the same detented control that you have on the left stick. Now I can fine tune my depth keeping with another click if I need to. The older version of Kevin Mcleods ADF is just the ticket. Couple that with the smooth hull and torpedo shape that it has and everything is very predictable. One thing that I learned was that the endpoint adj. that you can make on your radio has nothing to do with the range of movement that your APC or ADF induces to the servo. I dialed down the endpoint on the stern planes only to find out that when you tilted the sub the ADF was still over extending the planes, jamming them in place. Ive got to go into the Subdriver and move the pushrod linkage on the servo to a hole in the arm closer to the shaft to reduce the throw and then dial the endpoints back up. Live and learn.

Another thing I learned was , just like the Titanic found out, clear water next to a iceberg or a patch of weeds does not mean safe passage. Here you can see a NO FEAR OSCAR snarled and snagged in weeds.

[KevinMC]

Re: Scale Ship Oscar 2

Hi Mark,

I'm glad to see things are coming together for you with the OSCAR, and that the ADF is doing just what it's supposed to do. A point to note on control throw limits, you're actually not the first person to remark that the pitch controller "had a mind of it's own" with respect to servo limits. That's why part of the setup for the ADF2 is to "teach" it your control throws so it won't overdirve your servos.

As for your comments about turning radius, have you tried differentially driving the throttles? I know it seems rediculous that two screws 3" apart on a 5' long hull would have any effect on steering, but don't knock it 'till you try it! At lower speeds it makes a world of a difference.

[greenman407]

Re: Scale Ship Oscar 2

So you are saying that if you are going to make a turn to the right you would obviously set your rudders to hard right and your starboard prop to run at say quarter throttle while the port prop to run at 3/4 throttle or more. Yes I have heard of that and thats one thing I will try in my next outing. Thanks for the input. I also want to gauge the difference between submerged and surfaced turn radius.

[KevinMC]

Re: Scale Ship Oscar 2

I tend to go a little more extreme on the throttle difference - full on the outside screw and nil on the inside, but yes that's the idea. If I'm travelling really slow I'll actually reverse the inside screw, but I'm always careful when doing that. Also note that the effectiveness of this technique reduces with speed. The other thing I've noticed is that with respect to the throw on the rudder I sometimes get a sharper turn with 3/4 throw than what I get with full throw. (Which tells me I have too much throw on my rudders when at speed.)

On my OSCAR the turn radius when submerged is remarkably better than on the surface, although I've never taken note of either in a quantitative manner. (Sounds like an excuse for another outing!)