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[neilgwilt]

Hi
Not sure where to post this  so hope its gets to the correct source. Building HMS Amethyst (Deans Kit). The aim is to use independent power unit control, ie using the left and right sticks on the RC box. As the engine drives are either side of the keel, do the engines rotate the props and thus screws in opposite directions. ie port rotates anticlockwise, starboard clockwise. Or the blade rotates towards the outside of the hull.
Thanks
Neil

[Rob47]

oh dear this always contentious and is split into two camps.  I have always used port and starboard turning inboard and it works well for me, although I try to use information from the actual ship, also Merchant navy and Royal Navy do differ.
Bob

[Martin (Admin)]

I read somewhere that props turning inwards, ( at the 12 o'clock position ) gives more speed, and
props turning outwards, gives you more manoeuvrability....



      ...... or was it the other way round?     




             Somebody will corret me!
 
 
 
 

[colin-d]

I guess it all comes down to what suits the job, and everyone has there different ways..


Personally...
If the ship only had one centre positioned rudder.. then I would direct the thrust from each prop onto the rudder..  so single rudder, props turning inward...


If the ship has two rudders.. then I would rotate the props outwards...


But being as you are using independent throttle sticks to control each motor independently then it probably wouldn't matter which way round the thrust came...

[Peter57]

I think I read the opposite to Martin, i.e. outwards gives more speed - but I may well be wrong! 


I have just about finished building a semi-scale (approx. 1/24) landing craft which has two motors and no rudder. Rather than using a twin stick system I am using a mixer in "tank" steering mode. Hopefully, it will work!


As Colin-d notes, as you are using independent throttles it probably does not matter too much.

[neilgwilt]

Thanks Guys

[Geoff]

If I recall correctly inboard turning props are slightly more efficient so may give a slight increase in speed (all dependent on the type of model of course). Outward turning props tend to give more maneuverability due to the paddle wheel effect, basically walking the stern round at low speed - bearing in mind real ships would probably use one engine at a time for close quarter maneuvering.


Cheers


Geoff

[derekwarner]

Here she is as a Builders model in the Greenwich Museum.......


If you enhance this image as available on the WEB, you will clearly see and answer your question = inboard turning props
[Port = clockwise, Stdb = anti-clockwise.......or opposite to your proposed comment]

You may also find other views of her in the HK Drydock after the 1949 skirmish.......[as confirmation, as even Builders models can be questioned]


Derek


[PS....how far is it from Wolverhampton to Greenwich?]

[NickelBelter]

From direct experience:  you won't see much difference with a Black Swan hull whether the props are TTO (tops turning outboard) or TTI (tops turning inboard).  Perhaps someone has a photo of the real ship in dock, showing the actual arrangement of the screws...

What really improves handling is independent or mixed motor control.  That said, it's a long hull with relatively closely-spaced propellers so don't expect it to spin in place like a tugboat would. 

[Umi_Ryuzuki]

We always built our military ships with outward turning propellers.
Port- anti clockwise, starboard- clockwise.
It would lift the stern going forward, and suck the stern down in reverse.

That being said, here is a video of the HMS Amethyst in dry dock.
The Port propeller appears to be anti clockwise rotation.
 https://www.youtube.com/watch?v=RV4DoSRAVes

[derekwarner]

Must agree Umi_......., HMS Amethyst in the HK dry dock post the skirmish damage clearly shows the Port propeller as outbuy turning [image below]

So for accuracy with Neils build, this now closes out the question .....outbuy turning propellers

The only thing we can say is the Builders model in the Greenwich Museum, has the main propulsion appearing as not as used on the 1949 deployment in the Far East.....saying this, the images do suggest a quality model

Derek

[Akira]

Photo documentation is almost always the best source. Builder's plans and models are often quite misrepresentative of the real ship. These days, it appears to often be the case of intentional misrepresentation. Almost anything presented to the public as an "official" example of a weapon system, ship, aircraft, tank, ect, must be viewed with skepticism. Rightfully so, I would think.
Great find Umi!