rgrove

I have 2 NIB Lindberg PT-109 kits (about 29" hull?) I had one when I was younger, and just bought a house on a lake, so I am getting back into RC boats.
I know zilch about electric power systems as they relate to boats. I have electric planes can cars, and have the chargers, etc. for those, but never was able to figure out marine power.
Anybody have any thoughts/recommendations on powering this PT? The kit came with a small electric motor, through flimsy gears, to twin screws. Would like to keep the twin screws, and maybe even the gears, but what motor/battery/speed control?
Any thoughts would be greatly appreciated!
Thanks!
Ron

pompebled

Hello Ron,

When I'm correct, it's a MTB (Motor Torpedo Boat), right?

This hull, at only 29 inches long needs to be kept as light as possible, in order to get it on the plane properly and have decent running time.

What size motor did come with the kit? If you don't know, measure the diameter and can length (without the shaft).

What gear ratio are the gears, what size props are provided?

Do you want to run it (semi)scale, or does it really have to fly?

I myself are no great fan of gears, the noise ruines the scale appeareance, it consumes power and the reliabillity is not great.

Do you have a few pics?

Greetings, Jan.

rgrove

Hi Jan. Thanks for the reply.
What do you mean by "MTB"? Im not familiar with that...
I am travelling for business now. I will try to find out motor dimension s(I know it is tiny), gear ratios, etc. this weekend. Ill see if I can post a pic of the kit.
Any help is appreciated! Thanks!

Xfactory

My Feedback: (3)

My Lindberg PT has 2 Speed 400 motors direct drive and moves along on plane just about right. MTB is a British term I think,
Motor Torpedo Boat

pompebled

Hi Ron,

I googled around a bit and I think that two speed 400 motors in direct drive, like Xfactory said, is the way to go.
Ask him about his setup (motors, batteries, ESC, receiver, etc.)

Good luck!

Yes, it's all the same type boat:

MTB: Motor Torpedo Boat ( like the PT, no steps)
M.A.S.: Motoscafi Anti Sommergibile ( the stepped Italian version)

Greetings, Jan.

Xfactory

My Feedback: (3)

I find it intresting the different sizes of torpedo boats, I have a collection of 1/72 scale MTBs and the PT boat is very small compared to the Vosper, S-100, Japan PT-15, and E-boats with the PT-15 being the largest by far.

LtDoc

rgrove,
Take a look here;

http://www.modelboatmayhem.co.uk/

Martin has a pretty good (and simple) explanation about motors, batteries, etc. I wouldn't call it 'comprehensive', but it does give you the 'basics'. (I'm sure there are several other places that do the same thing, this is just one that I know of.) Sometimes you have to do a little 'translating' between "UK english and US english, but it isn't that difficult.
Electric motors don't have to be huge to be the right size, and the 'factory' recomendations are usually enough to at least make the boat seem 'close' to scale in performance (if not better). The important thing is to have fun in the building and the running...
- 'Doc

PS - Gear drives aren't the 'best' option in the world, but they do have their uses. 'Belt drives' too, although they seem to be a little harder to find at times.

pompebled

Xfactory, this is the Ilalian one.

@Lt Doc, the beltdriven reduction runs very smooth (when properly set up), The use of ballbearings in both motor and propshaft is highly recomendable, because of the one sided load, the stock bronze bearings wear out rather quickly.

I used and adapted a (Olympus) belt reduction (1:2,3) for planes, it allowed me to run a 42mm Xprop on a high revving carmotor on 7 cells, in my 75 cm M.A.S., worked like a dream. For a PT-109 however a tad too big.

Jan.

Tachikaze

DO NOT gear reduce this boat! As XFactory mentioned, the use of the 400 motors is a good idea. I would highly recommend the use of two screws so that you will limit torque lean from a single screw. If you can get counter rotating props this would be even better. My combat Schnellboote in 1/72nd scale uses two HPI RS4 mini motors with counter rotating props. It will get up out of the water fine with these. They are direct drive and run for 20+ minutes under combat conditions with a 1500mAmp battery.

rgrove

THanks to all for the replies. I am thinking twin 400's might be a good solution. XFactory, what speed control and props do you run? Also, are you using a standard 7 cell carr NiCd pack, or something different? 20 minute run times with solid performance sounds about ideal.
Thanks again to all for the input. It will be time to start building soon!

Xfactory

My Feedback: (3)

I am using 2 Jeti JES 600 speed controls, 1 would work but I wanted full independent control of both motors. for props right now I am using Graupner 3 blade 30mm counter rotating props, they work well but I think more speed is there by playing with some different props. As far as batteries I am running HRSC 2600 Nimh 7 cells and run time is longer than I can stand there for, I estimate 20-30 min at least.
Another model thats great with 2 Speed 280s is the Tamiya Japan PT-15, excellent model that runs great. Tamiya has re issued the kit but Trumpeter has knocked it off and it's a lot cheaper than the Tamiya. Length is around 24"

Xfactory

My Feedback: (3)

By the way I am using the 6 volt motors with cooling coils, not sure if the coils are needed but the water squirting out looks cool. I made mine by filling alum tubing with water and capping the ends, put them in the freezer until frozen then wrap the tube around the motor.

rgrove

XFactory, one other question I forgot to ask... What scale/size is your boat? I just realized thatt here are (were) 2 Lindberg PT-109's a 15" hull and a 29 1/2" hull. I have the larger of the two.
Thanks VERY MUCH for all of the input from everybody so far!
Ron

Xfactory

My Feedback: (3)

I have the same one as you, it would be kind of difficult fitting twin Speed 400s in a 13" hull.

hyde-park

Hi Xfactory, I'm building my 1/32 Lindberg PT boat pretty well much on the lines of yours. This was even before I knew of this website? Can you provide pics of yours? Hope to hear from you! Hyde-park