HMS Lion by Ian_Grant - 1/150 - RADIO - RESTORATION - WW1 Battlecruiser

[Keith Black]

Great work, great story, Ian. 

[Ian_Grant]

Just a quick pic or two.

 

Printed the magnetic and gyro compasses for the bridge. Came out pretty good for such diminutive parts.

 

I can't find any info as to equipment present in the spotting top. I felt certain there must at least have been one of those gadgets with a circle graduated in degrees, and an eye-scope one points at a distant object to read off its bearing. Here's my rendition, in the top. As it turns out, with the overlapping cover in place over the top, one can hardly see into it but I'll know it's there as well as those few who peer into it.

Edited June 23 by Ian_Grant

[Javelin]

13 hours ago, Ian_Grant said:

one of those gadgets with a circle graduated in degrees, and an eye-scope one points at a distant object to read off its bearing.

For what it's worth, the bearing device is called a pelorus. 

 

The stand itself is called a binnacle or compass/gyro repeater. I'm however not certain if in that time they actually had repeaters or if it was a fixed rose that would give relative bearings (relative to ship's bow that is)  rather than compass bearings.

Nowadays we take gyro bearings with these things. 

 

Sorry for interrupting. You're doing an excellent job. Quite an improvement over your original version!

[Ian_Grant]

I was thinking fixed relative to the bow 🤔.  I later thought, "Wasn't it just v-sights rather than an optical tube?". Oh well.

 

Thanks for your comments and encouragement!

[ddp]

the Princess Royal outboard/inboard drawing i have on my computer as fitted does not show anything in the spotting top.

[Ian_Grant]

RC boat club has our annual demo at the "Stewart Park Festival" in Perth in a couple of weeks, conveniently located 8km from our cottage during our next stay. To this end I would like to get Lion on the water. I will probably take my sailboat too in case the wind obliges.

 

I greased up the propeller stuffing boxes then mounted the twin 540 motors, along with 6mm-4mm couplings, and 4mm U-joints I had in my parts box from the 70's. 😏

U-joint close-up. I have a handful since I had several boats running back then. I like the two-ball joints since the motor and prop shaft axes need not intersect. Due to the greater distance from baseplate to shaft centre compared to my old Decaperm motors, I could not get the prop and motor shafts to align; dropping the motors lower would have meant almost nothing to screw into underneath them! 

Conducted a motor current draw test with my 5C NiMH pack. A single motor draws 620mA @ 6.3V on the bench ( almost exactly the manufacturer's no-load spec), and the same driving the propeller in the pool. It's obviously not feeling the load; I could probably have gone with smaller 385 motors😠. But anyway, 1.2A @ 12V, times two motors, 2.4A; I'd drain the 3Ah lead-acid down in about an hour at full speed (I think). A little more battery oomph would be nice.

 

In fact, I'm sure a single 540 motor would deliver sufficient power for both props if only I could order a gearbox with my random shaft spacing. I could do it with belts and timing gears but it would be a trick to get counter-rotation. On the other hand, is it even necessary in a scale model boat at scale speeds?

 

Also I am considering putting the twin ESC units on different channels so I can run on one motor only, most of the time.

 

In future I could try fitting two identical propellers and drive both from a single motor via belts, to save battery draw.

 

In the meantime I have added some detail.

 

Main director, and spotting top glued and painted black. The masts above the funnel tops are black too. The fore topmast isn't tapered or painted or glued in so far.

Aft searchlight platforms added, with more anti-splinter railing mats. Access is by ladders hidden in this view. Need to add some metal bulwarks behind them. Considering adding another searchlight each side; not historically accurate but it gives a nice balance between fore and aft searchlight groups and I like the look as seen in the 3D render (which is inaccurate in other ways too!).

Extra searchlights in the 3D render.

I've also been busy printing more deck furniture and gluing in place. Here is what surrounds "Q" turret at present.

The flat circles are coaling scuttles.

Bridge with rangefinder, chart table, both compasses, access ladder.

Thanks for following and commenting.......👍

 

Ian

Edited 8 hours ago by Ian_Grant

[ddp]

would not the motor go in reverse if you reverse the polarity with the battery?

[Ian_Grant]

Hi ddp:  Yes of course. The ESC units take care of that, reversing the voltage (or not) depending on whether I move the transmitter stick up (Fwd) or down (Rev).

 

Rereading my post, I think you misunderstood when I mentioned "gearbox"; I only meant a metal box with two shafts connecting to the prop shafts and a single shaft connecting to a single motor, with internal gears to connect them and rotate the prop shafts appropriately. Not a mechanism with forward and reverse gears! 

[Ian_Grant]

Footnote:  I looked up the motor manufacturer data. Using 385 motors instead of 540 would give me about half the torque, at half the current draw. Since the 540 drew zero additional current with the prop in water as opposed to air it must have abundant torque for the task. Sigh. Could have had half the draw and twice the cruise duration. 

 

I am going to try two identical propellers and if there are no adverse effects (I wouldn't expect any) then change the internals to drive both with one of my motors, thus doubling the duration. Maybe I could sell one motor and one ESC on to someone in the club? And my never-to-be-used 6V battery. 😞

[Javelin]

With two identical props you will have a stronger propellor effect when reversing. With counterrotating ones this balances out. 

Depending if you go for right or left handed props, the bow will very strongly move to either port or starboard side when reversing. Which then means that whenever you'd want to reduce speed, you need to take into account a heading change and turning of the vessel. Rudders don't work when props run backwards, so you can't compensate for it either. 

 

That's the only disadvantage I can think of. Perhaps also vibrations that will increase instead of cancelling each other out, but that's difficult to predict. 

She's looking sharp!

[ddp]

Ian, do both props spin in the same direction or does 1 spin right & the other spins left?

[Ian_Grant]

3 hours ago, ddp said:

Ian, do both props spin in the same direction or does 1 spin right & the other spins left?

I have re-installed the same pair of counter-rotating plastic propellers from the 70's.