Thornycroft mtb 49

[Michael Cole 8Participant @michaelcole8]

Hi,

I'm building a Thornycroft MTB 49 to drg MM337.

Paxolin is specified I'm thinking of using 25 mm plastic overflow pipe

Also the power unit is a Marine javelin. Denis Brouet used and replaced his electric 540 motors with what is not mentioned in January mag.

Any help or suggestions appreciated.

Kind regards Michael.

[Michael Cole 8Participant @michaelcole8]

[ashley needhamParticipant @ashleyneedham69188]

Paxolin for what, exactly?.

A 28mm outrunner of say 1300 Kv on a 6 cell Nimh might be a decent replacement motor, dead cheap motor/esc combo on eBay…aircraft esc so forwards only but dead cheap.

How big is the boat?.

Ashley

[ashley needhamParticipant @ashleyneedham69188]

Ah, just looked it up….is a biggie at 36 inches so something a bit bigger needed. A 540 would struggle.

Perhaps a 35mm outrunner then. Loads out there, don’t go for a mega watt motor. Kv dependant on motor and prop size.

Ashley

[David Marks 2Participant @davidmarks2]

I cannot visualise the relationship between Paxolin and Plastic Waste Pipe. I have used Paxolin before, but not in connection with a model boat. I used it in sheet form as an insulator i.e. it was called up on the drawing of a piece of equipment that I had to make as part of my job.

[Ray Wood 3Participant @raywood3]

Hi Michael,

I imagine your talking about 25mm torpedo tubes from PVC pipe which would work fine, but quite thick walled may look a bit chunky ? I used some thin walled aluminium tubes for my MTB 71 from old garden furniture, but that was 20mm for the right scale.

Paxolin was widely used back in the 1950's probably when Vic Smeed designed the boat, there is similar lighter material from SLEC for joining model glider wings etc, I won't attempt to spell it

Regards Ray

[harry smith 1Participant @harrysmith1]

Hi Mike

A Banggood Surpass Hobby C3542-1250kv, 2 to 4S Lipo battery(850Watts on 4S).

On 2S 9000 rpm, 3S 13875 rpm and 4S 18500 rpm (unloaded).

Shaft 5mm, standard 35mm(540 motor mount.

Prop 2 blade 35/40mm.

ESC 2 to 4S 80Amp.

On 3S about scale speed, but, you can option up to 4S with only a battery change.

Banggood have a C3542-1450kv the same size.

On 2S 10444 rpm, 3S 16095 rpm and 4S 21480 rpm(1050Watts on 4S).

With these two motors, a 3S and 4S battery this will cover you for that size boat.

Harry

[Denis BROUETParticipant @denisbrouet95531]

Hi Michael,

I stuffed up on my reply as I only signed up yesterday and failed to scroll down the page!

I made the torpedo tubes out of fibreglass by wrapping light weight material around a piece of 7/8" dowel. A similar process was employed to make the torpedoes, but I had to machine the dowel to to acheive a diameter of just under 7/8".

For propulsion, I installed 2 Turnigy D2826-10 1400kv brushless motors coupled to 35mm Rivabo props. The motors are powered by 2 7.2V 5000 mAh NiMh batteries in series and 2 50A ESC's. The performance and attitude of the hull in the water is totally realistic.

In order to fit all this in the hull I deleted the hull crutches during construction. I've had no structual issues with the hull since I built it in 1975!

Denis

[Colin BishopModerator @colinbishop34627]

You can buy lightweight plastic electrical conduit in 20mm and 25mm sizes. It is thinner walled and lighter than plastic waste pipe and costs under £3 for 2 metres. I used it for the funnel on my paddle steamer.

Screwfix sell it.

**LINK**

Colin

[Michael Cole 8Participant @michaelcole8]

Hi ,

Thanks for your replies and suggestions for torpedo tubes and power units. Where do I start or go about installing Radio control please.

Kind regards Michael.

[Colin BishopModerator @colinbishop34627]

Some general background information here:

**LINK**

If you buy a budget multi channel radio it should do all you are likely to need.

**LINK**

The Planet set is well regarded but you can spend more..

**LINK**

Colin

[Chris FellowsParticipant @chrisfellows72943]

Hi Michael

Are you going with one motor or two and brushed or brushless? This will have an impact on what other components you will need and their installation. Also are you comfortable using a LiPo battery or prefer NiMH?

Chris

[ashley needhamParticipant @ashleyneedham69188]

Hi Michael.

Useful info. Go to the “features” tab (along by the forum/home one) and choose technical articles, scroll down to “I don’t understand electrics” article by the late great Dave M. Very useful.

As Colin says, the planet set is good, with cheap receivers if you need to get more.

Ashley

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