Darnell RN S class plans

Thanks Swipe, I will be investing in one of those pumps shortly, is there a store that sells suitable ballast bags? Also could I use normal tubing like model aircraft fuel line material?

Right looking at t'other end of the sub, was thinking of using one shaft from wtc running both shafts using a gearing system, once again does anyone know of a source for brass cogs and gears?

Thanks for all the info again guys

David

Before you part with your hard earned £20 or so, maybe Swipe could say whether he has actually used one or that it simply seems like a good idea?

Do you have to have brass gears?

https://www.theassociationofmodelsubmariners.com/t555-motors-and-gearboxes-from-mfa-como

http://mfacomodrills.com/

https://www.theassociationofmodelsubmariners.com/t1119-technobots-good-useful-supplier

http://www.technobotsonline.com/

Are both good for supplies of gears etc - but probably more in plastic.

Suppliers of ballast bags - you've hit on the main problem. Finding a suitable bag?  Reading around, lots of people seem to have used various medical bags (dialysis etc??) but would you want to trust your sub with them? Maybe someone can offer some actual long term experience of using one successfully.

Hi

I have been having a clear out to-day and one of the things that I came across is the Darnell pump with the motor, would this be of any help??

Hi Fred I would be very interested in the items, just let me know how much you would want for them, anpother question Im afraid whats the best way to waterproof the control linkages and prop shafts at the stern?

David

dgp1957 wrote:Hi Fred I would be very interested in the items, just let me know how much you would want for them, anpother question Im afraid whats the best way to waterproof the control linkages and prop shafts at the stern?

David

Hi
First just p/m me your address, cost just the cost for the posting,

Second you need to talk to Alf Blake with regards to sealing push rod's.

Fred

Thanks for asking some good questions!

You have energised me to move some useful threads over to the Beginners Start Here section. Hope the threads are useful.

For the record, I use Simrit shaft seals and bellows.

David

Where do you buy them from David?

Below is a post David put in another section earlier today.



"Just got a set of O rings from this supplier.

(They also do shaft (oil) seals such as Simrit and also bearings.)

Sensible prices and postage and next day delivery by first class post."


]http://simplybearings.co.uk/shop/index.php?osCsid=bc25a0eff9daea1c50bef28c4c549995[/url]

Guys just to clarify, would I drill a hole of the outside diameter of the seal through the WTC end, glue the seal into the hole then pass the prop shaft through the seal?

David

I have just tagged some more info onto this earlier thread:

https://www.theassociationofmodelsubmariners.com/t266p30-prop-shaft-seals#8709


Hope it helps your fitting. I think that with reliable prop shaft seals you may re-consider putting side by side motors in rather than a single motor and twin props. Twin motors can help in turns a little.

David

Guys would this suffice for a ballast tank:-
http://www.ebay.co.uk/itm/FUEL-TANK-nitro-or-gas-petrol-500ml-rc-model-boat-with-clunk-pickup-500cc-/361061600190?_trksid=p2054897.l5662#ht_1692wt_1161

David

Hi David.

Are you going to Blank off the  fitting on the bottle side to give a pressurised tank
OR set the tank up as a vented system?

If the former, then check that the thread is sufficient to withstand pressure.

500cc with a pressure system = 300cc actual (say) which is 300gms weight,
will this be enough to overcome the boats buoyancy?

regards

John

Hi David, I don't think that tank could stand the pressure (about 300 KPa or 3 atmosphere) if you want to use the pressure tank system. It is a very good question so I have just started a thread on pressure ballast tanks in the Beginners section.

David

You might find this installation amusing but it works reliably.
The 150cc home made clunk tank is filled with a lorry windscreen pump (24v running on 12V) and the capacity is enough for a static dive. The air from the tank is displaced into a normal rubber balloon which helps to evacuate the water later and keeps the water from entering the WTC.
The balloon should be as thick as possible for safety, get mine from a party balloon shop.
Its due for renewal before the next sailing season.

I will stress that this is used in my first sub (over 10 years ago) when I didn't know any difference.









John.

Nice one John! I think I like that best of all the "baggy" & "bladdery" solutions. It will pressurise the WTC though and how do you stop the balloon from bursting if you run the pump for too long?

easy peasy, the balloon is inserted into a toilet roll tube (not shown in photo) which gives it a physical dimensional restraint to about the size of a conference pear which does not create too much of a WTC pressure. The boat is ballasted to dive with the tank 2/3 full so pump is switched off via the old Mk1 Eyeball system and the compressed air does give a fail safe effect.

I do recollect that the balloon would not have been used if I had found a bigger bottle.

John