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[drover]

I'm beginning to think of a new project to start. I'm an experienced builder of static models but very naive when it comes to working models. I have built and glad to say successfully sailed a Clyde Puffer but my only other two working models have been sail driven. After seeing a model of a WWI destroyer in a museum I have for a long fancied building one and am considering doing this as a working model. The puffer with its single prop did not present me with any problems, but the destroyer has four props and as a novice I'd like to know a bit more about the propulsion side of the build before making a final decision.


For instance is it necessary to have all props powered or can it be set up with just two being driven by the motor (I'm assuming a single motor and gearing would be best given that at 1:48 scale the boat will be about 1200mm long, 130mm in the beam ). Any other advice, book recommendations etc,  relating to the "engine room" much appreciated.


Thanks

[hmsantrim]

Hi Drover.
 from reading the blurb you don`t seem to be too bothered about the scale underwater appearance. SO! if you want to make it a single shafter go for it if it makes sailing easier.  I dont expect you will be entering any competitions so you can use the ubiquitous "modellers licence" with the engineroom design.   
 
 frank   

[Time Bandit]

I would at least use 2 props.
Those tight destroyer hulls have problems with their turning radius, so if you use at least 2 motors and a V-mixer you can turn on the spot.

To be honest, why not making all 4 work?
4 little motors directly on the shafts and the most left and most right motor on a V-mixer.
If you go with brushed motors you need just 2 speed controllers, with brushless you need 4.

4 of these should be perfect depending on powersource and props
http://www.componentshop.co.uk/385-dc-motor.html

[John W E]

Hi ya there Drover,

Can you tell us what model destroyer you are hoping to build?     As the majority of destroyers were twin shafted and the occasional one had triple screws.   As far as wiring up and running 4 screws is concerned, have a look at the warship section on here and you will see a build of HMS Exeter 1939 build - and she has 4 screws - they are driven by Graupner 500s and the speed controller is an ACTion P94 which has a built-in mixer.

aye

John

[Plastic - RIP]

I would go for 4 props & 4 '385' or '545' brushed motors - it's so much simpler. Use 2 speed controllers and a V-tail mixer or activate that mode on the transmitter if it has one.

It saves mucking about with belts & gears.

[radiojoe]

As you have already done a single shaft you would have no problems with four, but I can't think of any destroyers that had four shafts, also check the size at 1:48 a destroyer would be considerably longer that 1200mm more like twice that.

[drover]

Hi all, thanks for response.
At the moment I'm very much just tossing a few ideas in the air. Work and family commitments will have to be a big factor in what, if anything, I decide. This may have to actually be a project for when I retire once I've researched a bit more.


Maybe a bit misleading stating WWI, the model that inspired me was of a destroyer of the late 1800s/early 1900s but no longer remember its name. I know I can get plans of a similar destroyer in "The First Destroyers" by David Lyon. It is HMS Velox and I think its length overall was in the region of 200 feet x 20feet which scales to 1270mm


Cheers

[radiojoe]

Not sure how you worked out the length, but HMS Velox D34 was 300 feet long at 1:48 scale or 1/4" to the foot it comes out at 75" or 1905mm.

[drover]

This has gone a bit away from my original query about whether it was feasible to have 4 props on the model but only have two providing the propulsion, which may be a stupid question to many of you but as I stated I am pretty much a beginner when it comes to working models. The main reason for asking was just a general query I wondered if there would be space in the hull for all the gear, the puffer I built had a considerably roomier hull.

As for the final size of the model that would be determined once I had the plans. At the moment I worked out the dimensions from my memory of browsing David Lyons book in a bookshop some time back, but just now I did a google search for Velox to see if my memory was close. I found this link gives details of the size which tie in with what I remember of the dimensions given in the book.




http://www.shipmodels.info/mws_forum/viewtopic.php?f=13&t=24567


OK if these dimensions are correct it appears I was about 15 feet out.


However the bonus of doing the search is that I've also discovered there is a post in the warships section of this very site by someone building a model of this very destroyer, a proper read of this when I have more time may help make up my mind about the project. One thing it does show is that Velox did have 4 propellers.

[J.beazley]

Sounds like an interesting project your taking on and a nice looking destroyer she is too.


Back the original question as a suggestion I would look at running the 4 shafts on 385 size motors which shoud fit nicely in the hull side by side
or consider belt drive system using just a pair of bigger 540 size motors each running a pair of shafts.


Jay

[Netleyned]

Thought the difference between 300 and 200 was 100

At 1/48  75 " and 50"
25"

Ned

[inertia]

http://www.action-electronics.co.uk/wd.php
Scroll down to the following drawings:
Fairmile D - Mike Harris
Graupner HMS Hood - John Tew
Graupner HMS Hood - Richard Cord
HMS Eagle - Graham Heald
Large Battleship - Eric Sims
All have four motors and use various combinations of "mixing" inner and outer motors. I would advise against having un-powered (dummy) props and shafts - they act as drag anchors.
DM

[John W E]

hi there

here - if you scroll down the page - half way down you will see a picture of the set up inside HMS Exeter of the ACTion P94 setup - driving 4 motors

http://www.modelboatmayhem.co.uk/forum/index.php/topic,33734.msg365345.html#msg365345

I have done a web search and have found some varied information on this destroyer that you are going to build.  As far as I can gather, she had 4 shafts, but 8 props - i.e. 2 props per shaft.   Now this will be an interesting build - because some of the models I myself have seen on the web only have 2 shafts, with 2 props and if you go onto Wilkipedia and look there at HMS Velox, that comes up as only having 2 shafts.

Some interesting reading.   I am wondering what is correct.   

aye

John

[drover]

Thanks J Beazley, inertia and Bluebird for your latest responses to my propulsion query. The info on the action-electronics site in particular looks extremely useful. I am discovering more about this build and would really like to do it, if not as a working model certainly static. However one thing I'm realising as I investigate further, it is a lot more complicated than I remembered from my quick look several years back so it is going to have to be a slow build if I want to do it justice given the limited amount of free time I have at the moment.


As to the question of size (which never was a question but has become an unexpected side issue). Perhaps as I stated previously the use of WWI may have misled radiojoe. The Velox I'm referring to was sunk by a mine in 1915, HMS Velox D34 was I believe built in 1918 )


As I've already stated I was basing the possible size of model purely from memory of a quick browse some time back hence the use of the  word "about"  in my original post when I was giving a mere rough indication of the likely size I thought the model might be. The link I later posted gave the size of the 1904 Velox as "about 210 feet" In my last post this was what I was referring to when I typed "about 15 feet out " ( but too much wine on a Saturday evening clearly rendered me incapable of subtracting the 200 of my memory from the 210 of the article).


Rest assured if I go ahead any calculations will be based on the plans and I'll keep the wine bottle corked while making any changes to scale!!


Cheers!

[John W E]

http://www.wrecksite.eu/wreck.aspx?1235
http://www.tynebuiltships.co.uk/V-Ships/velox1903.html
Some interesting reading 

aye
john

[radiojoe]

Apologies Dover, I thought it must have been D34 to have four shafts, it was not my intention to confuse things, 

[drover]

Thanks Radiojoe, maybe my question could have been worded more clearly, and I'm sure you were intending to be helpful.

[radiojoe]

Thanks Dover, hope you do your four Shafter, I've only done two shatters up till now, I'd like to build one if I can find room for it.

[drover]

Just as a follow-up some info that might be of interest to those of you who responded.


I had mentioned to a workmate that I was interested in building a model of Velox he said  that he had a relative who was had a keen interest in naval history and had a large book collection. Result, in one of these rare moments of serendipity, I now have been able to borrow a copy of "The First Destroyers" by David Lyon complete with a 1/8in plan drawn by John Roberts.


According to the Velox was launched in 1902 and completed in 1904 and was 215ftoa x21ft x9ft


The plan shows 4 shafts and 4 propellors. The chapter on Velox  covers a lot of Admiralty concerns about design and performance and mentions a Design B with a 3 shaft arrangement proposal but  a comment about the ship's actual performance states "that only the two central shafts were used for manoeuvring"


Interestingly  "despite bow rudders never having proved satisfactory" the Admiralty allowed one to be fitted to give higher speed astern with full steering control.

However a report also stated that "I have always considered Velox to be a most unsatisfactory destroyer when worked with a flotilla" and gives a list of reasons including poor performance when going astern. It ends with the recommendation that it be turned over as an instructional vessel in torpedo and wireless telegraphy which would "not necessitate her going to sea in anything approaching bad weather"

Do I dare risk sailing such a ship on my local pond ???


Confusingly the plan states the fate of Velox as being mined in 1915, the text however states that Velox lasted till the end of the First World War in active service.


All good stuff, looking forward to reading the rest of the book. Once again thanks for the advice

[malcolmfrary]

The only downside of scratch building a particular model to a given scale it that it might get mistaken for a build from a kit or semi kit.  http://www.chyldshallmodelshipyard.com/Hull%20and%20semi%20kit%20catalogue%202..pdf