Topic: Twin TVR1A (Read 2858 times)

brassman · « **on:** March 14, 2021, 04:04:10 pm »

Hi

I have been reading the posts on Mayhem for many years and posted a little about my long term project to build a model Titanic several years ago. The model is 6ft long - 1:144 scale and the hull is made of brass plates soldered onto a frame. I started it [embarrassingly] over 30 years ago and before the wreck was found!
Now I am at the stage of fitting its power plant. Titanic was triple screw so my idea is a central electric motor and twin steam engines. I have built two TVR1A engines and have hopefully appropriate clockwise/ anti clockwise propellors. I have built the TVRA's as identical engines but now I am wondering if I should have built one as a mirror image? Should I just run one in reverse?
Incidentally to make life easier I intend to use the centre propellor with the electric motor for reverse which is the opposite set up to the original.

I would be grateful for any comments by the learned members of the forum !

David

DBS88 · « **Reply #1 on:** March 14, 2021, 04:30:12 pm »

That sounds really nice, would love to see some photos, have you decided on a boiler to power the engines? It is crucial to get the boiler size matched to the engine capacity otherwise there is the possibility of running out of steam, I wish you well with your exciting project

brassman · « **Reply #2 on:** March 14, 2021, 06:21:40 pm »

Thank you for your reply and good wishes.

I have attached some general photos. There is still work to do on the deck fittings, mast and funnels and ongoing repairs as this is already an old model!

With regard to the boiler I have a boiler which was built for me but at a time when my intention was to use twin Marcher engines. I realise they are smaller but I anticipate the engines running fairly slowly so I am hoping it will be ok.

Colin Bishop · « **Reply #3 on:** March 14, 2021, 06:24:39 pm »

That is certainly some model!

Colin

TheLongBuild · « **Reply #4 on:** March 14, 2021, 06:32:07 pm »

I will agree with Colin, have always found the Vessel of great interest and before it was found or the Cameron film
Love your model and would love to see more pictures, way back zI had plans to build her and did cut the ribs and still have them, think similar size to yours but that was as far as it got.

rhavrane · « **Reply #5 on:** March 14, 2021, 07:04:58 pm »

Bonjour David,
Based on my steam experience, in the steam world, some important things to be taken in account are :

1 - The size of the propeller regarding the machine (too small, steam consuming, too large, too much effort on the steam machine)

2 - The size of the boiler (ie its heat surface)

So

1 - The TVR1A is a 8 cm3, this means that you will need to feed 16 cm3. For my machines of this size, I use 4 blades 90 mm propellers, so the one I see seem correct. Your boat will not start navigating like an offshore but she will move (I foresee a big inertia for her, helped by the electric additional engine)

2 - For my 13 - 20 cm3 machines, I like using 125 x 250 mm horizontal boilers with a 40 mm in pipe and 250/300 g/h torch like this one : https://www.youtube.com/watch?v=42a9CLfYG9I and furthermore most of my large steam plants have a coupled pump to reach more than 30 minutes of autonomy because with large machines (> 11 cm3) my "babies" are quite heavy 20 - 40 kilos (certainly less than your one

)

Have you any idea of the future weight of your boat ? These are my first ideas, I a sure that other members will have other fruitful suggestions.

KBIO · « **Reply #6 on:** March 15, 2021, 10:38:31 am »

Hello Brassman !

Should I just run one in reverse?
To answer to your question : yes, you can set one engine running forward and one running in reverse .
Although, there will be a slight difference in RPM, a well-tuned engine runs the same way , IN or OUT !There is some cases where you can adjust the timing to get more RPM forward than reverse but forget it in your case.Your project is fantastic and I am eager to see the result !Have. good time.Kind regards.

rhavrane · « **Reply #7 on:** March 15, 2021, 07:07:53 pm »

Bonjour David,
I fully agree with Kbio, you would not feel the difference between the two machines and it is even a great pleasure to have two separate engines for a double propeller boat https://www.youtube.com/watch?v=ckakDalgPfY and even more on a paddleboat : https://www.youtube.com/watch?v=qLmOZyA-yKQ

brassman · « **Reply #8 on:** March 16, 2021, 01:30:19 pm »

Hello and thank you everyone for your kind replies.

It is a relief to know I can run one engine in reverse!

Here are some photos of the boiler. It has been stored for many years [I bought it with the optimistic idea that I could finish the model in a couple of years!]
It is a heavy beast and has just a couple of water tubes.
I would be grateful for advice regarding finding an appropriate burner and then my idea is to run a horizontal copper tube from the boiler flue to connect with upright tubes extending into the ship's funnels. I am a little concerned about the heat dissipation in this arrangement - The funnels are moulded plastic - perhaps a polyester?
I have a couple of old computer fans that I have in mind to ventilate and cool the interior of the hull .

I will post some more photos later .... [and I will measure the propellors but I bought them as scale replicas]

David

brassman · « **Reply #9 on:** March 16, 2021, 01:34:20 pm »

oops - forgot the attachments !!

rhavrane · « **Reply #10 on:** March 16, 2021, 06:53:35 pm »

Bonjour David,

For my boilers which have a 40 mm diameter heat pipe, I like using 250 - 300 g / h torch burners and adapter rings.

On this example https://www.youtube.com/watch?v=DQdXzxUYL4o I have bought these acessories to a French manufacturer who works on demand, JPB

Other example https://www.youtube.com/watch?v=42a9CLfYG9I made by JMC, other French manufacturer.

About your boiler, my concern is its size, quite thichk and too small to my opinion to have some autonomy and even perhaps enough steam for 16 cm3 to be feeded. It is quite far of the 125 x 250 mm I use. How many ml does it content between the two limits of the water level ?

Geoff · « **Reply #11 on:** March 17, 2021, 11:04:12 am »

On my steam powered destroyer Velox I actually used old black plastic 35mm film pots with the bottoms cut off for the top of the funnels as it gave a nice lip with plastic water pipe for the base of the funnels. Inside I run an alloy inner funnel which gets hot but the plastic is fine.

For wire rigging may I suggest Beadalon - its 7 strand jewelry thread.

Like the model

Cheers

Geoff

brassman · « **Reply #12 on:** March 17, 2021, 12:24:28 pm »

Thank you Rahael and Geof for more help!

I have attached a photo of the propellors and a bit of the stern arrangement. To me it is a good reminder of the tidying up I should do to many parts of the model -and to buy some brass/ copper cleaner!

Am feeling very humble about my abilities when I watch the youtube videos of your models Raphael - such superb and detailed engineering.

David

brassman · « **Reply #13 on:** March 17, 2021, 12:25:58 pm »

forgot the attachments again!!

DBS88 · « **Reply #14 on:** March 17, 2021, 12:40:32 pm »

Thank you for the additional info that your are providing, the thing I have learned from this forum is that getting the prop right for steam is probably one of the most effective and cheap improvements that you will make to the boats performance in terms of speed and duration of running, a larger steeper pitch prop will make much better use of the steam. A scale size and style prop is great for show, but for running on the lake a larger prop with steeper pitch will keep the revs down and make the steam last longer. Prop Shop do a nice range of steam props with a pitch of 1:1.5 rather than the scale props pitch of 1:1 I have changed the props on two of my models and the improvement gained is immense

brassman · « **Reply #15 on:** March 17, 2021, 06:18:24 pm »

After the photos of bits looking a bit grotty I thought I would add a couple of photos of the lighting ...

rhavrane · « **Reply #16 on:** March 17, 2021, 08:46:25 pm »

Bonjour David,
I confirm again, the "good" couple propeller / machine is particularly important.

Your propellers are not appropriate for steam at all, especially 8 cm3 machines, sorry.

Your boat deserves high quality propellers, I would kindly suggest you to ask Simon information about his products (these are mines) : https://www.youtube.com/watch?v=EN0drJGsdDo who has become https://www.youtube.com/watch?v=nGRDus7uIJQ
Example : I saved 30 % to 50 % of autonomy on these boats by changing their propeller : https://www.youtube.com/watch?v=TVl2NCWmyXA
And as we usually say "one picture is worth 1 000 words"

xrad · « **Reply #17 on:** March 17, 2021, 11:03:37 pm »

WOW! insanely cool model!

for LED control..maybe check out some C++ programmable microprocessors like Teensy 3.2...can run MANY inputs and outputs ...easy to program...

KNO3 · « **Reply #18 on:** March 19, 2021, 10:56:42 am »

Hi, to answer your question about having two mirrored Graham TVR1A engines: it is actually very easy to build one as a mirror image of the other. Since both are built identical now, you will only need to turn one around, so the reversing levers are on opposite sides. Than on that engine place the flywheel at the other end of the crankshaft, then remove the steam pipes and replace them to face the boiler.

steamboatmodel · « **Reply #19 on:** March 19, 2021, 11:28:56 pm »

Remember with the funnels only the forward three are used as stacks and would have steam and smoke going up them. The rear funnel was used for ventilation.
Gerald.

News:

Author Topic: Twin TVR1A (Read 2858 times)