Vosper MTB ‘engine room’

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29 April 2016 at 00:10 #65047
Jim Masson 1
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@jimmasson1
A newcomer to model boats and would appreciate some advice. I am about to start on a Vosper MTB 379 from Barrie Griffin's plans. The model is 1/32 scale and is about 72cm LOA.

In his notes on his build he states he fitted twin Como Stingray 500 motors. I have not been able to find these, presumably they are either not available or have undergone a name change. Any suggestions for a suitable alternative? I'm assuming there is a clue in the number so would something like the Mtronics 500 or MFA 540 be suitable alternatives?

Any advice on choice of speed controller and battery would also be much appreciated. I've been modelling for years but just started on working models so a bit unsure of the power side at the moment. (2.4 Ghz was a revelation, seems a vast improvement on the R/C for the Tamiya car I built for my son about 20 years ago!)

Thanks
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29 April 2016 at 00:10 #5421
Jim Masson 1
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@jimmasson1
29 April 2016 at 05:46 #65048
harry smith 1
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@harrysmith1
Hi JIm

Was the Tamiya car the Falcon?

I Still have mine but with a Trackstar 2400kv brushless motor on a 3S(11.1 volts) 2650mah Lipo battery.

It is TOTAL INSANE!!!

Why the old 540 motor was 90 watts and the brushless is 550 watts.

As for the Vosper what size props and number of blades will help with the motor size.

EG 28mm brushless 1200 to 1500 kv on 2 blade 32mm or 3 blade 30mm props work OK.

35mm brushless 750 to 1000 kv 0n 2 blade 40mm or 3 blade 35-37mm props work OK.

If scale speed only the lower kv would be better.
4 May 2016 at 13:04 #65135
Ray Wood 3
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@raywood3
Hi Jim

I think 400's would be fine, you want it to get up on the plane but not fly, I'm currently building MTB 71 which is 30" long, I do build light as I've done my share of Aeromodelling. I'm, using 2 X MFA 400 size motors with 25mm 3 blade brass props.

Regards Ray
5 May 2016 at 08:47 #65137
ashley needham
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@ashleyneedham69188
-Jim. For the brushed option, and if the hull is light I would agree with the 400 motor choice, but if you were to leave a bit of room behind the motors, a speed 480 (which is a bit longer) will be a straight replacement for a 400 and provide a bit more power if needed.

Do you have any batteries to start with ?? a 7.2V Nimh (the "standard" flat 6 pack) would be a starting point but obviously LiPo batteries are much lighter if more demanding with the charging and so on. The usual Mtronics Viper ESC will do, 20A perhaps, but if using Lipo you will need one of those small low voltage bleepers to monitor the battery voltage in the boat.

Brushless would be an option, a 28mm outrunner perhaps of 1200Kv or so as suggested by HS1, but two brushless ESC will be needed off a Y lead (has anyone tried two brushless motors off one ESC???)

Someone out there has built something v similar and needs to post asap with their motor combination!

Ashley
5 May 2016 at 09:13 #65138
Dave Milbourn
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@davemilbourn48782
(has anyone tried two brushless motors off one ESC???)

I have heard tell of a person who has managed to do this successfully (I'm not sure I believe it), but for all practical purposes you need one ESC for each motor. I would tend towards the 28mm brushless outrunners of about 1000kv with 3S batteries and a 30mm 3-blade prop each. The little 30A Hawk ESC is a nice little piece of kit; I have three in my fleet **LINK**

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