Robbe U47 Static Conversion

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Hi All
l have been given a Robbe U47 dynamic diver and am going to convert it to static diving. I have the bayonet locking rings from Norbert Bruggen. I was hoping for some advice on the best glue for fixing these to the WTC. Is Stabilit Express the best option or is there something better?

many thanks

Adam

[Subculture]

Stabilit Express is difficult to get hold of these days. However it's just a modified acrylic adhesive and there are plenty of equivalent product. Devcon Plastic Welder I and II, Uhu Acrylit plus, Deluxe Materials Super Crylic, You can also use a good quality epoxy like JB weld marine or Araldite precision (slow cure epoxy). Ensure all parts are well keyed with abrasive and degreased before bonding.

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Hi

Thanks for the reply. Will the alternative glues suggested be OK to bond to abs? I managed to get a large pack of Stabilit Express from local model shop. My plan for the boat is to machine new, longer abs end caps in order to accommodate the spindles of 2x500ml engel piston tanks. I am new to RC subs and have been reading a lot on this forum and others. Am I correct in thinking that a ballast tank at each end of the boat is the best option? My understanding is that the air pressure inside the WTC will increase as the ballast tanks are filled. My concern is that the butt joint for the inner bayonet ring could fail or end caps could blow out and so want to make sure I use glue that will provide the strongest bond. I intend to machine a collar for the bayonet ring so that it fits tight over the WTC a bit like Boattrainman did on his conversion.

Adam

[Subculture]

Twin piston tanks will give you very accurate control of the boats trim without affecting the c.g.

No concerns with the glued bayonet fitting if you use the Stabilit Express. The glue is very strong and joint will be of large cross section- you could happily swing off the ring. The forces from the compressed air behind the pistons of the piston tanks will amount to probably about 150-200N maximum acting against the joint. Of more concern will be the shafts exiting your boat, make sure the bellows and any other shaft seals can cope with the pressure inside, which I would estimate will be somewhere in the region of 0.15-0.25 bar

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Thanks again for advice. It is much appreciated. I am using simmering prop shaft seals as shown in Norbert Bruggens book and have purchased the 3mm o ring control rod sealing assemblies from him. Do you think these will be up to the job?

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They'll be fine.

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Does anyone have experience of the Maximus Modellbau ballast tanks? I get the impression from some posts they are much slower to fill than the Engel piston tanks? Would they give as much control of the boats trim? They are considerably cheaper than Engel and appear an attractive option. Any comments and views would be greatly appreciated.

Thanks

Adam

[DMTNT]

Does anyone have experience of the Maximus Modellbau ballast tanks? I get the impression from some posts they are much slower to fill than the Engel piston tanks? Would they give as much control of the boats trim? They are considerably cheaper than Engel and appear an attractive option. Any comments and views would be greatly appreciated.

Thanks

Adam

No experience with his tanks, but I've done business with Danny and can speak to his character. He's a good guy. Very helpful and quick to reply. Just be aware that shipping from Germany can be a bit touch and go. It's nothing he did, but it took almost a month and a half to get a tiny box of parts delivered to Seattle.

[Subculture]

They use a small geared water pump. They'll be a lot slower than an engel piston tank(s) comparing like for like. If you want an inexpensive system consider using a larger geared water pump (Kavan pump is excellent) pumping into a vented tank. Such a system will only cost about thirty or forty pounds or so, and you won't pressurize the wtc.