A U-Boat In Ireland

[The Boattrainman]

Hi my friend.

On a first pass, I couldn't make head nor tail of the thing, but as the years go by, and I go back time and again with more knowledge I discover what Norbert means.

There's a need for a total upgrade of the book now, it's become very dated in parts, though the basics and science are still very much the same. There's a need for a step by step primer to help total newbies (the web is probably where most learn), referencing new kit manufacturers, new equipment, new opportunities for kit bashing, and how it's not as daunting as it used to be to make a half decent model sub. The best model books I've used (railways, helis, tanks), explain the science and techniques, then take the reader through a build up of a model or two to show how it's done.

Rob

[The Boattrainman]

A throw reverser is built into the front hull, using a large plastic former epoxied into the hull and with two brass screws through the bottom which will be covered by filler.




The reverser ensures front and rear dive planes work against each other and also lifts the connection point from the snake higher so it doesn't have to bend too much.




Middle and forward hulls are bonded together by standing one on top of the other and using a length of elastic string to ensure they are straight, the fit is so good nothing is needed to hold it all together, one of the kits good points.




The WTC is bonded into the middle hull and all the bulkheads are now installed, but not where the kit instructions suggest, instead they are set under the Wikinger deck where it is solid.










There are five bulkheads in the shot below, and a short section will be removable for access to the front planes and the reverser.




One final bit of kit cleverness, there are round pieces of 3mm styrene that are bonded to bulkheads and the WTC that just touch the inner hull giving great strength.




At the bayonet lock the bulkhead is bonded to the top of the ring dead in line with the edges, as there will have to be a very tight fit as both hull sections rotate against each other to open/close.




Sealing the WTC permanently into the hull is not ideal, I would like to be able to slide the WTC in and out, but the kit design uses the WTC to solidify the hull!

The Boattrainman

[The Boattrainman]

Here is a schematic of how the whole dive planes mechanism will work.





The area that will require a bit of a think is where the bowden cable breaks at the hull join..................!


The Boattrainman

[He Who Shall Not Be Named]

Here is a schematic of how the whole dive planes mechanism will work.





The area that will require a bit of a think is where the bowden cable breaks at the hull join..................!


The Boattrainman

Don't mechanically link the stern and bow planes. They will only work at a specific speed and depth. All other areas of the operational envelop will give nothing but grief ... porpoise city!

David

[The Boattrainman]

I hear ya buddy.

Can you talk me through this, what's the diff between this and having the fore and aft linked at the Transmitter end using a mixing programme?

Rob

[trout]

I guess the point is still don't. The front is for depth control and the aft is for your leveler. Separate channels or some levelers do not even need a channel, set and run.

[He Who Shall Not Be Named]

I hear ya buddy.

Can you talk me through this, what's the diff between this and having the fore and aft linked at the Transmitter end using a mixing programme?

Rob

Rob,

Linking the bow and stern planes to work in lock-step -- either by transmitter mixing or mechanical linkage -- is the wrong way to proceed.

Bow planes are for depth control. The stern planes are to control the boats angle.

Typically the stern planes have a longer moment-arm (distance from where the force is applied in relation to the vehicles center of rotation) than the bow planes. The bow planes, more closely coupled to the c.g. tend to exert a dynamic force up and down rather than a rotational moment, which is achieved with the stern planes.

If your r/c system does not have enough channels to permit independent control of these two surfaces, then put the stern planes on an angle keeper and leave that device to autonomously keep the boat on or near to a zero bubble-angle, with you out of the loop. But, do control the bow planes so you can control the submerged models depth.

David
(stood helm and planes watches on the TRUTTA, and WEBSTER)

[The Boattrainman]

Brilliant Dave.

Thanks for the explanation, I get the set up now. Will be able to put the Auto Leveller on the rear planes and the fore planes under direct control. Just need an extra opening for a third servo.

Just as well I put that schematic up before going any further.

Rob

[The Boattrainman]

Here's a revised schematic, going to be a busy aft section, as the rudder servo and On/Off switch have to be factored in.








The prop shafts are now set in line, the photo below shows the difference with the kit prop shroud and it's new location.




It's all nicely in line as per the prototype........................ but..................




.................the prop shafts are seriously low down in the hull, with only 7mm of a gap between them and the WTC wall, just enough for a universal coupler, but no way can I direct drive to the motor shafts! This is clearly why the kit designers had the shafts angle upwards towards the bow, interesting times ahead.




The Boattrainman

[He Who Shall Not Be Named]

The 'reach-around' to get the pushrod running forward from the after face of your WTC should not be so complicated. Try this:






Drop the Bowden Snake and install a floating (magnet at each end) aluminum tube pushrod between motor-bulkhead and bow plane bell-crank. KISS!!!!!


David

[The Boattrainman]

David,

Yes, def thinking magnets for the break point on the fore plane push rod.

Just on another note, the discussion on having no linkage between the fore and aft dive planes got me thinking, what's the best set up for the Skipjack. Currently I have the Auto Leveller on the aft planes of the Skipjack and then an electronic mixer in the Trans driving both the sail planes and the aft planes, now I'm thinking that's not ideal.

Rob

[He Who Shall Not Be Named]

David,

Yes, def thinking magnets for the break point on the fore plane push rod.

Just on another note, the discussion on having no linkage between the fore and aft dive planes got me thinking, what's the best set up for the Skipjack. Currently I have the Auto Leveller on the aft planes of the Skipjack and then an electronic mixer in the Trans driving both the sail planes and the aft planes, now I'm thinking that's not ideal.

Rob

Ch-1 rudder
ch-2 sail planes
ch-3 throttle
ch-4 ballast sub-system
ch-5 stern planes

Disable the mixing between stern and bow planes.

https://www.youtube.com/watch?v=tDUGjTX_tXo

https://www.youtube.com/watch?v=wm8F5i0-Btg

https://www.youtube.com/watch?v=bo9Mp9nuoB4

David

[The Boattrainman]

Thanks David.

Will try that this weekend, couldn't figure why the Skipjack was such a handfull to control.

Rob

[He Who Shall Not Be Named]

Thanks David.

Will try that this weekend, couldn't figure why the Skipjack was such a handfull to control.

Rob

Set it up as I describe and you'll be pleasantly surprised. (poet and don't know it)

David

[The Boattrainman]

One thing rarely modelled on the Robbe sub is the stern torpedo tube outlet between the rudders, here's how I did it.

A rough shaped hole is cut to the shape.




13mm plastic tube is inserted, then cut to length.




The tube is marked with a pencil to the shape of the hole.




The tube is cut around the pencil marks to give a complex shape.




This shape is dropped in the hole and drops of super glue are dripped around the edges, small pieces of round plastic reinforce the join




The joints are filled.................




...............and sanded to give an even finish, a large drill bit to the diameter of the hole was covered in sandpaper and used to extend the curve to stern.





Drill bit standing in for exiting torpedo.




I've no idea what the door looks like, will have to wing that bit.

The Boattrainman