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Newbie Robbe SeaWolf

R/C Submarine modelers

Postby Chuck Chesney » Sat Feb 21, 2009 12:47 pm

Thank you very much for the insight and construction tip. I'll give my neighbor a spare radio, battery and anything else that he needs to help him get underway with a minimum of extra expense. Even at the low $300USD cost, it's still a major capitol investment for a fourteen year old.

Maybe someone knows a U.S seller of the model, because every buck that can be saved on postage is important on this project.

Thanks again.
Chuck

"The Japanese solders would die for the Emperor, which made them formidable. The U.S. Marines would die for each other, which made them invinceable"...Iwo Jima
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Postby junglelord » Sat Feb 21, 2009 1:03 pm

A&J Hobbies Ltd. has the instructions on line and the model

This is your hook up
http://www.ajhobbies.net/product.asp?pid=2377
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Postby Chuck Chesney » Sat Feb 21, 2009 1:51 pm

Junglelord, thanks a million. I've got a young man looking over my sholder, and drooling right now. I'll give this request for U.S. sellers a couple of more days, to save postage costs, then A J Hobbies will get the sale.
You've been a great help, and I've printed your construction tip regarding the bow section for the actual construction.
Thanks again.
Chuck

"The Japanese solders would die for the Emperor, which made them formidable. The U.S. Marines would die for each other, which made them invinceable"...Iwo Jima
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Postby junglelord » Sat Feb 21, 2009 7:08 pm

More advanced members with the SeaWolf have told me its an excellent submarine, I cannot wait to actually take it out. Check my post again, I often have to edit. I know I added in information on the use of the 90mm O ring and also grabbing a left handed prop.
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Postby aquadeep » Sat Feb 21, 2009 7:57 pm

I read that you dont want to use the dive planes,not a good idea especialy since it a dynamic diver.As much down ward control will be needed to keep it down and for better control at scope depth and slow.

I tried it once without forward planes and it was very dificult to dive at slow speed .This sub is very well desighned out of the box and its handling is par none. Just my experiance :D

Harbor Models or Ships N Things also sells this model.
Dave :D
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Re: Newbie Robbe SeaWolf

Postby Warpatroller » Sat Feb 21, 2009 9:37 pm

Rubber boots for the control arms and some vaseline on the rubber O rings for extra seal. Guaranteed not to leak.


In the manual for the sub kit I have, it states not to use petroleum-based grease (like Vaseline) for the O-ring pressure hull seal. It says instead, to use silicone grease or vegetable shortening (like Crisco) as the petroleum based grease may cause crazing and/or cracking of the lid and top of my pressure box (which I think are made of ABS styrene plastic).

I'm not sure what material your pressure hull and end caps are made of, but I just thought I'd share this info with you.
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Postby junglelord » Sat Feb 21, 2009 11:30 pm

Thanks for that tip on proper sealent.

Dave I read that I should have the bow and stern planes working in concert, with this particular set up and design....is that correct?
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Postby Warpatroller » Sun Feb 22, 2009 2:13 am

I of course am not Dave :lol: But, I will chime in on the dive plane question.

From the info I have come across in the past on here, if your going to have both bow and stern planes functional there are basically two choices for best performance:

1) Have both sets of planes move in unison in opposite directions. Bow planes down, stern planes up (to dive) and bow planes up, stern planes down (to surface).

2) Control only the bow planes via your transmitter and have the stern planes hooked up to a pitch controller (or automatic leveller). This option is better for more realistic and smooth depth changes and allows for easier depth keeping while cruising at periscope depth.

I can't offer this advice from actual first hand experience though, only from what I have read from the experienced guys on here. I plan to go with option 2 on my first (real) sub, which I am just now preparing to start on.

I'm sure Dave or someone else will verify my information though soon enough. Oh and your welcome on the sealant tip.

Steve
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Postby junglelord » Sun Feb 22, 2009 2:38 am

Thanks, that makes a lot of sense.
I appreciate that.
Cheers.
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Postby Crazy Ivan » Sun Feb 22, 2009 1:45 pm

The topic of bow planes vs. stern planes pops up every now and then. I put in my 2 cents worth a while back in this thread:

http://s181686668.onlinehome.us/phpBB2/viewtopic.php5?t=6098&postdays=0&postorder=asc&start=0

One method I'm pretty sure won't work is trying to dive a dynamic diver by only controlling sail mounted planes. They likely will never even get wet. :(
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Postby junglelord » Sun Feb 22, 2009 2:03 pm

Crazy Ivan wrote:OK, let's see now:
Could you please explain why you made the following statement:

"It is not advisable to try to couple the bow and stern planes together to run them both from a single channel."


Short answer: My own experiences and the sage advice of those who came before me. Longwinded technical dissertation: Well, let me see if I can articulate this clearly. As I previously posted, the bow and stern planes act in distinctly different ways, at least on the military subs we typically model, be they of the Seawolf, Gato or U-Boat type. There is a reason for this, and it starts with the center of gravity and its location.

Any forces applied to a submerged hull by the rudder or dive planes will cause it to rotate around the center of gravity. If the center is too far forward, there is extreme stability and the turning response becomes very sluggish due to an effect known as weathercocking. Too far back and the hull becomes dynamically unstable, making control difficult. Anyone who has built and flown model rockets will recall the importance of properly locating the center of gravity relative to the center of dynamic pressure.

The balance between stability and control response is generally achieved in model subs by locating the center of gravity somewhat forward of the middle of the boat, maybe in the area of around a third or more of the way back from the bow, depending on the boat. This means that the the bow planes are relatively close to the center of gravity, so they "tend to change the vertical position of the submarine on an even keel. There is a certain rotational moment, but it is counteracted to a great extent by the longer after body which acts somewhat as a stabilizing rudder, resisting angular displacement." (All quotations are from The Fleet Type Submarine training manual)

The stern planes, on the other hand, will have a relatively large rotational moment arm which will result in a change of pitch, and "their effect is much greater than that of the bow planes." In addition, when the submarine "is inclined, the hull presents planing surfaces. The resultant upward or downward thrust is added to that of the diving planes." The upshot of all this is that, in our scale, when the stern planes are used to angle the boat for diving or surfacing, the effect of the bow planes is probably negligible. The bow planes may as well be fixed in position, avoiding all the extra linkage. A lot of boats run successfully this way (although sometimes at the risk of finding your tail in the air, with the prop sucking wind because you gave her too much throttle, too soon, with too much down angle on the sternplanes!). It's happened to my Akula and other boats I've seen at the subregattas.

So then why can't the bow and stern planes be coupled together? Won't the boat still dive and surface? Absolutely! Steve's Type XXIII is a case in point. Knock yourself out. But after the novelty of going up and down wears off, it becomes a matter of control... very precise control. Many of us derive great satisfaction when we can get our boats to run steady at periscope depth, particularly with hands-off on the joy stick. If the bow planes are to be used at all, de-coupling the functions of the bow and stern planes enhances the likelyhood of success, with the boat running on an even keel.

There is one circumstance where hooking the two together might be beneficial, and that is the case of a boat like the Seaview. Dave Merriman has noted that the bow planes in this case (NOT the Sail Planes!) are far enough ahead of the center of gravity that they would impart a rotational force that would enhance the effect of the otherwise poorly performing stern planes. Maybe this is also the case with Steve's little Type XXIII, depending on how far back he located his COG. The Trumpeter Seawolf that started this discussion, at 29 inches long by 4.5 inches beam, I would expect to fall more in line with the conditions stated above.


Now that really hit home...I get it.
Thats the best explanation about this whole question that seems to include the true variables that are to included in such a question. COG, control surface size, relationships between the two. Nice light bulb over my head right now. Thanks Ivan
:D
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Postby Warpatroller » Sun Feb 22, 2009 4:35 pm

I remember that thread now! That quote by Crazy Ivan was actually an answer to a question I had posted. Like I said, I plan to have the bow planes on the transmitter stick control and the stern on an APC.

But, as far as trying to have them move at the same time via the same channel from the stick, I wonder if the following might allow for at least decent control:

The stick control activates both sets of planes simultaneously, with each set hooked up via their own separate linkages and servos. The two sets move in opposite directions, like I stated above, but they move at different rates of travel. The bow planes would move further up and down than the stern planes. The stern planes would rotate less than the bow. This would have to be done, by trial and error, running the boat, then adjusting the throw of both plane linkages until the best setting has been achieved. Granted this is more difficult than just using an APC alone on the stern planes but may gain better control on a boat that runs poorly with only functional stern planes and/or when there is no budget for an APC (which is probably around $70). Of course this is theory alone and I have not tested such a layout.

I agree with Ivan in saying that having only the sail planes on the Seaview functional (with fixed bow planes), would not do much if the boat was a dynamic diver (at least when trying to dive from the surface). The sail planes are up in the air out of the water, making no contact with the water when initially trying to dive. Therefore, they would have no effect until the sail is submerged. A dynamic diver relies on deflection forces of the planes and forward motion of the boat, as a joint effort, to submerge the boat and to keep it submerged. I think Steve Neill said his Seaview only has functional stern planes, but keep in mind his boat is a static diver, it is not a dynamic diver.

Steve
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Postby junglelord » Sun Feb 22, 2009 4:42 pm

So, in essence, since a Snort is not a static dive unit, a Seaview so outfitted would benefit from said bow planes.

A RCABS Seaview could operate in a different mode being fully static.

Without bow planes, but with a fixed vane in the nicelles, I should have a boat that still handels properly. Of course thats based on the Debor build notes from David.

I of course fully understand that functional sailplanes mean NOTHING until they are in water. I figured that having them would be of advantage when submerged. That of course would seem to be correct. Thats was my intent.
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Postby Sub culture » Sun Feb 22, 2009 4:57 pm

Having played with a Seawolf, I can tell you it will be much more fun to dive if you ballast it so that only the very top of the deck is above the water.

Too much positive buoyancy on a dynamic diver requires a high speed to submerge.

I'd also recommend a leveller, that will really transform underwater handling.

Andy
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Want to dive your boat in crystal clear water? Then you had better Dive-in- http://www.diveintomodelsubmarines.co.uk
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Postby Warpatroller » Sun Feb 22, 2009 5:23 pm

Didn't realize you were going to run a "Snort" system. In that case, it no longer is strictly a dynamic diver. And if your going to be running the Merriman/Caswell sub-driver then your boat will be a static diver. My boat will have a gas/schnorkel ballast system (my boat is German so I use the German word for it :D ) It will be similar to the Merriman system, except since the XXIII used a retractible schnorkel mast on the real boat, my air pump will be sucking air through the model's schnorkel mast instead of some little tube hidden inside the tower. So I'll have a scale looking schnorkel that really works! :D

Steve
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