Robbe U-47 - Building help

[gearbox]

Hello all; I have finally bit the bullet and after years of admiring these wonderful submersables, I have purchased a Robbe U-47 kit. Really wanted a WTC pressure hulled example, but couldn't really find one that I could buy all in one place. And since I'm new to submarines, I thought it would be better (easier) to get the dynamic diver. Plus the Robbe was well detailed, had good reviews, and looked that it was well engineered. Plus, I wanted a U boat (I think most new hobbist goes for the U boats first). I do have to admit, I am very spoiled by the Tamya and Kyosho kit cars and helicopters which outside of building, requires very little in the way of jury rigging and customizing to fit every component. I'm not opposed to it, but I just didn't know that much about it yet.

Now with this said, I'm looking for some advice on the building of this kit. I read on this site some time ago, several mods for the kit for adding additional servos for the dive planes, replacing the motors with more efficient ones, recommended batteries, and the possibility of fitting a WTC. Are these articles still on this site somewhere? If not, can any one lead me in the right direction? I know this kit is like a bathroom toy for most of you out there, but I figure if I could deal with the size of moving this around, find a place to run it, and proves to be as much fun as I think it would be, I'll be building a WTC model in no time. Also looking for a good radio recommendation. Thanks Allan

[safrole]

There's not much online dealing

There's not much online dealing with modifications to the stock layout. I have a little page on the addition of a 750ml Engel piston tank and shaft seals to replace the stuffing tubes. Check out www.subconcepts.com for those items. He will also sell you some different motors.

Here is the link to the page with the pics of the modified equipment rack. U47Modifications.htm

It's true the Robbe is not as "high end" as the models that get most of the chatter around here, but she is a classic, like the type VII itself. Plus, everyone (und ihr bruder) has one. Start checking out non-English sites and they are rife with Robbes.

I know I personally wanted something priced at an entry level, but worthy of later upgrades. I also wanted a WW2 "classic" sub, either a U-boat or a Gato, and I was impressed with the Robbe's rack design, since I was pretty sure I would be doing a lot of maintenance inside the boat and it looked very accessible. Over all, it really fit what I wanted with my budget.

[sam reichart]

Really wanted a WTC pressure

Really wanted a WTC pressure hulled example, but couldn't really find one that I could buy all in one place. Thanks Allan

Allan-
Welcome aboard...
Just curious about this comment. You could have purchased the OTW Type VII, with an OTW WTC ballast system from Bob Dimmack, and all you would have had to add is a radio and batteries. I'm not second guessing you purchase, or whether or not his boat was right for you; all I'm stating is that it is possible to buy a Type VII with a ballast system, from one vendor.

[safrole]

Hey I wanted to chime

Hey I wanted to chime in about the servo for the front dive planes. I was going to do that myself, but instead stole an idea from someone on this board (forget who) to just link the front planes with the back ones. One servo runs both, but the link from the back to the front is "sloppy" so that the front planes are only flipped up or down at the extreme of the rear planes' motion. I've been told there should be a little friction on the front planes so they don't flutter in their dead zone. I attached the linkage as closely as possible to the axis of the front planes' motion, so that their throw is still decent. This plan keeps you from waterproofing a servo, but still gives you an extra aquabatic kick when you want it.

(If I ever finish the boat I'll let you know how it goes.)

[JWLaRue]

Hi Allan,

Welcome to the world

Hi Allan,

Welcome to the world of r/c subs!

Since you are starting with the robbe U-47, you might want to consider picking up two of the back issues of the SubCommittee Report that each have an article about building this kit and adding a working ballast system. Issues #46 (September 2001) and #55 (December 2003) would be the ones to get. Back issues can be purchased through our membership chairman, Jim Butt (membership@subcommittee.com).

-hope this helps!

Jeff

[safrole]

Yes those are good issues

Yes those are good issues to read up on. Also there is www.marinerc.com which has some buildup tips.

Something about the ballast is that the Robbe really needs about a litre of reserve bouyancy to float at the correct water line and still dive statically, and even more with extra stuff topside. Even my crammed-in 750ml piston tank will only yield a semi-static diver, technically. I will run the water line a little high and make it fully static.

Subconcepts will very soon have just the thing available, though. I suppose I'll just have to be patient.

[gearbox]

Hello All, Thanks for the

Hello All, Thanks for the great input. As I said, I was new to this albeit researching it for quite a few years. Obviously there was alot more than I found. But with the kit in hand I decided that a dynamic diver was not for me, so the search led me to Jason Overhulser's Site and Gary Heathcoat's site and many Euro sites with many ideas. These sites appeared to show the Alexander Engle 750 ml to be the tank of choice. Although some sites showed a compressed air system, the relatively few dives per charge and the high probabilty of not getting it back up detered me from pursuing that method. At Jason's suggestion, I found Frank at Sub Concepts who hooked me up with the tank, an auto trim module, seals, BTS, bearings, etc. not to mention picking up Jason's brass deck. However, Frank advised that the 750 tank would not be sufficient to completely dive the U47 without forward momentum thus making it a static/dynamic diver. This confirms Safrole's findings with his sub. But Jason, on the other hand said his sub is ballasted so the waterline is about 1/2 inch below the decks (LOWER THAN NORMAL) and it submerges without the help of the dive planes, but has yet to put it through sea trails yet. Unfortunately, after buying everything from Frank I understand he is closing up shop. Too bad, great resource and nice guy. So

Subconcepts will very soon have just the thing available, though. I suppose I'll just have to be patient.

will probably not happen, but would like to know what he was going to offer.

Thanks Jeff for the lead on the back issues, will contact Jim and subscribe to future issues.

Sam, It was a lack of finding anything at that time. Most of the sites I found were the 32nd parallel type which only sold hulls. With the money I have invested so far, I could have bought an Alexander Engle kit and had a full static diver. Oh well, next time. If the Robbe goes well, I still may get the Gato kit. BTW, was Sub Concepts the only one here in the US that sold these kits? If not, please let me know who else I can go to. Thanks.

As of date, the kit still remains in the box, and additional parts are arriving daily. However, I'll be reviewing the instructions for a third time tonight. Just need a free day of quite to start. Looking into the Accurate Armour's conning tower and deck guns. Figure with Jason's cool brass deck, the OEM stuff just won't do it any justice. Jason's deck looks so nice, it'll be hard to paint over it..........maybe I'll just clear coat it and leave it shiney lol. Would appreciate anyones input on how to make the 750 tank work as a pure static diver and any other suggestions. Thanks again Allan

[safrole]

I don't like to directly

I don't like to directly controvert my buddy Frank, so I'll just "redirect".

I think it really depends on how much mass you have above the waterline as to whether or not the 750ml tank gives a scale waterline. And I don't think you have to cut off your tower to do it. <grin> Here's some pics of mine. The weights are how I was trimming it out this afternoon. I will post on the website by the middle of the week.

First is the fully flooded trim, with a red arrow showing the miniscus on the rim of the tower. Second is with the tanks empty, showing where the waterline hits on the model. I'm pretty satisfied.

BTW if you put in shaft seals, make sure to glue them in. I have a small leak, not at the shaft/seal interface but at the seal/outer tube interface. Now it's a real pain to get at.

[mickm]

I spoke with Frank today

I spoke with Frank today about "his answer" to this question. Wow, what a nice guy!
He is working in a ballast system for this boat. He does not have an E.T.A. for the new ballast system but says it will most likely be this spring.
I too am building a Robbe U-47 and will build my boat incorporating a detachable WTC (so it can be leak tested) until Frank has his available for purchase.
Hope this helps,
Mickm

[gearbox]

Hi all, I'm just getting

Hi all, I'm just getting sucked deeper and deeper into this project.............but this is a good thing. First of all I wish to thank everyone here for the generious amount of time and information that is being given me that is un paralleled in any other hobby that I'm involved in, and I do have a lot, lol. Additionally, I am learning very quickly that this is not a "buy a kit and build it" hobby. But rather a learn as you go pursuit. And much of it comes from how creative you can be. That's why I have decided to put all my efforts into this kit and make it do everything from static diving, firing torpedos, and what ever else I learn about or come across, which is happening daly.

Now with this said, I was contacted by Thierry Cervetti in the UK who has a very interesting method of ballasting the sub. BTW he was very generious with his time and answered my questions in volumes where I'm embarassed to bother him for some additional information.....well maybe I'll give it a few days anyway lol. Thierry compartimentalized the two saddle tanks on the sub for ballast tanks and added an additional one in the WTC without any major mods to the WTC or superstructure. The tanks are filled and drianed using a 12V car fuel pump located in the free flooding bow. A snorkel is used for air intake. Flooding the system gets the boat down to snorkle depth. Then a small bladder in the WTC is filled via another small volume pump to control depth to the bottom. Very clever I thought, Now if I can somehow utilize the AE 750 ml tank I bought from Frank in this system I'll be set. Thierry has a web site at Thierry's site . While his boat has not yet performed and sea trails yet, the 1.5L combined tank volume should be sufficient to displace enough water to submerge the boat and the adddition of the bladder should be able to control it's depth. Thierry seems to be an engineer and had done all the math so it works on the drawing board.

I have also contacted Frank to see if he could give me a clue on how his system works, price, and ETA. I'm in no rush, but would rather wait for the right system wether I have to build it or buy it outright. So in the meanwhile I decided to just get the kit ready to build. Anyone have any suggestions on the best way to cut out the hulls on this kit? Usually on vac-u-form parts I get a sheet of sandpaper, place it on a flat surface and sand the part until the edges fall away. Good for airplane canopies but these things are huge and thick.

Again thank you all for the great support and help given to me thus far, this site rocks, Allan

[safrole]

I made repeated cuts with

[color=#000000]I made repeated cuts with my heavy razor knife (stanley knife) and then cleaned the edge up with the Dremel.

One suggestion, given the cards you have to play thus far]

[tsenecal]

Gearbox & Safrole,

I used

Gearbox & Safrole,

I used a technique very much like Safrole's, except instead of a cotter pin throught the hole, I soldered a 1/16th inch brass rod into the hole, as well as soldering the rod as described in the manual. This worked for about a year (dozens of "cycles") before failure. The point of failure for my bolt was that the threaded rod cracked and split at the point where the hole for the cotter pin was drilled through it, after that, it started spinning like safrole's. I am having Chuck Anderson build me a new joiner bolt as we speak. I will let you know how well that holds up.

Tim

[tsenecal]

Chuck Anderson's replacement was built

Chuck Anderson's replacement was built as per the instructions (not pinned) and failed after only two uses.

[boatbuilder1]

it broke http://www.subcommittee.com/forum/icon_question.gif that s

it broke that s unexplicable
a hint I probably ommitted for the first fitting screw it in slowly and count the turns until its snug then turn in 1/2 more and test for leaks sorry send it back and I will fix it shipping it on me let me know what you would like or a refund what ever you wish

sorry never happend before these things are quite easily over tightened