Turbinia Motors

Hi Ashley

How heavy will the boat be when completed and do you want "scale" speed or something that is just fast.

Paul

Oo er, I never bother to calculate likely weights and so forth! the hull (bare) is 50" by 4 3/4 inches, an about as deep, and weighs 600g, 3x555 motors, for instance are 600g, 1x 6v 4.5Ah gel battery 750g, probly use at least 2 of them.. running gear and radio stuff (BEC for reciever) not an awful lot...probably a small amount of ballast to trim. I would like it to be reasonably fast, as obviously the original was the fastest craft in its day so you would want it to cut a dash and lift the nose clear of the water. What would SCALE speed for Turbinia be? I suppose it wouldnt have to be as fast as a planing Vosper type p/t boat.    Ashley

Hi Ashley

The Turbinia realised a speed of 35knots with a total of 9 props (3 on each shaft)

At 50in I would sugest a scale speed of 8 >10 mph which would produce an exact replica of the full size speed, to get to this I would advise a 700 center motor and two 400 wing motors coupled to 2 speed controllers.

Paul

Hi  Ashley  

 Turbinia was 103ft 9in long, so your model at 50in will be about 1/25 scale.

Using the scale factor can give you some idea of other characteristics of your model .

With the real thing weighing 44.5 ton (and if I can do the sums right)  would give a model weight  of 6.4lb (2.9Kg), also the real boat had 2000Hp which scales down to 97W  for the model, so using  6V each motor (3 in total) would draw about 5A when loaded properly with appropriate props.

The props (3 on each shaft) are 3 bladed with relatively narrow blades, Parsons had a lot of trouble with cavitation initially,  so spaced the pairs of blades well apart, each prop was 18in dia with a pitch of 24in this would be a blade angle about 30deg,

Cheers Tom

Chaps. I have discussed the motor options with various bods now and I think I will go (initially, at any rate) for 3x 600`s of some sort. In actual fact i will leave room to try other stuff, so it will only be a starting point. The problem at the moment is that I had a nice set of  9x30mm cast brass props and 3x3mm stainless shafts but the props have insufficient meat on the boss to grub screw them on with. I am considering using brass shafts and soldering the two mid-shaft props on instead..any thoughts on this? I am a bit worried that the wear may be a bit fierce, althought most of the bearings are water lubricated and the top can be kept oiled up.....? Ashley

Hi Ashley 

If the submerged bearings are constructed as a short prop tube i.e. with caps on each end that the brass shaft can pass through then you could use Vasoline or Lithium Grease as a lubricant.

Paul

Boaters. Two questions now

.a) the plans I have show,or suggest "cyclone 20" motors running at 6v.What would be the modern equivalent of them, and does anyone know what sort of power/revs these motors developed?

b) The plans do NOT show, but I have spotted on various photos, an exterior rudder quadrant on deck, pulled by steel cables. Handy this as room below decks aft is decidedly sparse...but what should I use to pull this quadrant around with??? Nylon line, small chain, polyester yarn?

As an aside, in 1902 the boat was re-propellored with just three slightly larger props (one per shaft now) so i may have a fallback plan.....!