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Supping Up the Robbe U47

R/C Submarine modelers

Postby Ahab » Sat Sep 13, 2003 9:26 pm

I'm a novice R/C suber. So novice in fact that I have yet to buy my first kit. I'm looking at the Robbe U47. But I want a Ballast system. I've been told that it's a good kit for what I'm looking for. I want a sub with Ballast system. And one with room that If I want to upgrade it with torpedo's, sonar, running lights, camra...so on it's got the room. I've also been told by an experienced modler that he ran both engines on seperate batteries. The review on this site says that as a dynamic sub it does not run for long. Has anyone out there upgraded the U47 like I am planning on doing? Well anyone other that the person who has been in contact with me. I just want to make sure that it IS a good idea.
ahah
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Postby kd6hq » Sun Sep 14, 2003 12:30 am

:cool:

Ahab

I am currently researching some of the same ideas that you are interested in. I have found some pictures that show a ballast tank (Engel 750m. size) installed along with torpedoes and functioning torpedo doors. There may not be enough room in the U47 for everything you list. I'm not sure about the sonar and have no idea how much room that would take up. The video should not be a problem - mostly a matter of money (as always). Take a look at this web site there are a lot of pictures - http://www.pbase.com/lynch/type_viii_u_boat&page=1

From what I have read the original motors / prop combination is not a good match. This shortens the run time significantly. "Ships 'N' Things" sells an upgrade geared set with a 3:1 ration which should get the minimum run time back to around 1 hour. To purchase the upgrade is a little pricey ($215) even though their web page says $200.

So Ahab if you decide to do this let me know I would be interested in your progress.

Don
Don

Keep the faith.....
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Postby Ahab » Sun Sep 14, 2003 9:46 am

Thanks for the info. I'll check out that website as soon as I get a chance. I'm a little bit weary. I want a good first kit. But I don't want to spend a fortune on it.
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Postby JWLaRue » Sun Sep 14, 2003 12:28 pm

Hello Ahab,

The robbe U-47 kit is a very nicely engineered kit, but I would hesitate to say that it offers the kind of expandability that you are looking for.....especially if you make the conversion to an operating ballast system with an Engel piston. When the Engel conversion is done, there is essentially no spare room left within the WTC.

You may be better served by starting with one of the many fiberglass hulls available.......

I would be remiss if I didn't also recommend that you join the SubCommittee (if you haven't already done so). Our quarterly magazine is a great place to see/read how others have built their boats!

-Jeff
Rohr 1.....Los!
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Postby JeffG » Mon Sep 15, 2003 4:10 pm

Got try on of the kits from Skip Assay. Easy striaght forward assembly, full ballast system. I added the Propel gass system and a subsafe so I can blow ballast from underwater. Very dramatic bubble sand all. Go for the Marlin, I saw it in the water at last years regatta, it sails thru the water beatifully.

Skip is also very helpful

JG :cool:
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Postby safrole » Thu Sep 18, 2003 5:20 pm

I bought a Robbe U-47 which is still a couple months from seeing water. I was in your place a while back and was severely tempted to get the Subtech Albacore, since I'd be able to reuse it's WTC in a U-boat or fleet boat hull at a later time. (That WW2 era sub is my favorite.) I also did not like the dynamic diving aspect of the Robbe, which is almost as toy-like as its little paddle diving control mechanism. (yuck)

But I went for the Robbe for 3 reasons. First I really wanted a U-boat and did not want to start out with anything else. Secondly I did not think there would be enough reserve bouyancy in the Albacore's WTC to float a U-boat hull high enough in the water for my tastes. And last is that I got a good deal buying the kit plus the 750ml Engel dive tank plus a pitch controller.

There's a lot of building with the Robbe, so on a budget go with the Albacore, unless like me you just have to have a U-boat.

I have also done some upgrading: I did away with the stuffing tubes and instead got some 4x11 mm shaft seals and got some 4x8 mm teflon sealed ball bearings which are normally used for electric cars' axles. I used different (imperial) sized brass tubes from my local hobby store to make handy little bearing holders and shaft seal holders. I also used the Dremel to open up the standard shaft supports just a little so they have bearings tacked in with a drop of CA.

Also I had the stock motors swapped for Johnson 540 ones which only turn about a third the RPMs. That eliminates the need for an expensive gear reduction unit. Of course I'm talking out of school because my boat is still in pieces on the bench.

I also got brass props and an Engel BTS and will be sealing up a servo to run the front planes independently. Instead though I may just attach another control rod to the rear planes and then run it forward to operate the front planes simultaneously. The linkage would snap together under the front deck, which is also where you would adjust it.

One thing to note. The Robbe would be best served by a one liter dive tank, but no one makes it. The 500ml fits well, but I hear the water line is very high. Better is the 750, bit it is a little bit of a struggle to fit in. It doesn't want to fit perfectly straight, and as the tank fills, the long bolt comes out just as long as the tank itself, so you have to have somewhere for it to go. That necessary void will be "reserved" in my WTC by a flared brass tube mounted off the end of the bolt. That way wires and crap can fall on it without potentiating any underwater disasters.

I've got some pics so far, if anyone's interested. There will be a formal writeup later. God only knows where the batteries are going. In fact I'm going to go post a question about batteries right now...

If you want to see the pics, let me know and I'll post them on my site tomorrow.
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Postby safrole » Fri Sep 19, 2003 12:39 am

Well I posted a page of the work on the Robbe so far, showing the installation of the bearings and shaft seals as well as overall concept I am pursuing with regard to the dive tank. Take a look and fire away.

--Jason

http://www.3rdgendecals.com/submarine.htm
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