USN Mk13 35th scale model torpedo more info

1/35th scale Model Torpedo - USN MK13 - more info

The ESC (speed controller board) may be one of these three types.

These three example printed circuit boards are completed and working (electronics only) 35th scale torpedo PCB's with three different brands of tiny ESC's (electronic speed controller's), these ESC's are essentially the same designs, all based on the Silicon Labs F330 processor (8051). The two speed control reed switches are US made and good quality "Littlefuse" versions and they are very (magnetically) sensitive.

The finished 35th scale torpedo complete with balancing weights and the new ultra tiny on/off switch. There are a couple of weights in the back section also. The whole finished 35th torpedo weighs 18 Grams and when it finishes it's run, it floats with the nose only out of the water. The battery is rated at 30mAH!

Production torpedo's are only available un-painted, the picture above just shows a possible colour scheme of grey at the rear and mid bodies and copper colored nose.

Torpedo Operation

The torpedo has a battery charging socket in the front, this is connected directly to the 30mAH Lipo, single cell battery and should be charged, as soon as received, with a good quality Lipo charger at no more than 30mA charge current and set for 1 Lipo 3.7V cell. a bare ended charging cable is supplied with each torpedo, the red wire is positive (+) and the black wire is negative (-), these bare ends will need to be soldered to an appropriate connector for your charger. The torpedo should be charged with the on/off switch in the off position.

There is an on/off switch mounted behind the charging socket, which is shown in the picture above in the "off" position. When switched on, the speed controller will make a beeping sound through the motor windings but as the reed switches are not close to a magnet the receiver emulator circuit, built on to the main board, will be set at high speed so the ESC will prevent the motor from starting, for safety reasons.

The torpedo front body can now be safely pushed in place. a small smear of vaseline or similar should be applied around the joint between the front and rear bodies to keep water out.

Waving a magnet near either of the reed switches (just in front of the gearbox) will cause the receiver emulator to go to the off or zero speed position and the ESC will make some more noises through the motor. The torpedo is now "armed" and when the torpedo is moved away from the magnet, the motor (and propellers) will start. Be careful of the propellers.

The torpedo can be launched from a roll off rack over the side of the boat or can be propelled out of a torpedo tube by air pressure or water pressure, the arming magnet needs to be mounted on the roll off rack or on the side of the (non magnetic) torpedo tube and aligned with the internal reed switches inside the torpedo.

The torpedo has a counter rotating gearbox and twin counter rotating propellers, so that it runs straight and true. Once launched it will travel in a fairly straight line, just below the water until the battery reaches it's cutoff voltage, at which point it wll slow down and stop. It will hang, props down, in the water with the nose slightly above the waterline and will need to be retrieved.

If you intend using these torpedo's in a large lake, or where you can't easily retrieve them from all around, you may need some sort of paddle boat at the ready, for the retrieval operation.

1/35 Torpedo Specification

Overall Length - 116.84mm - 4.6"

Overall Diameter - 16.27mm - 0.64"

Overall Weight - 18 Grams - 0.63 ounces

Run Time - TBD

Running Speed - TBD

The package

I send all packages with tracking so that they don't get lost. Often packages are held at the customer's local Post Office as they can be too large for the customers mailbox, so if it has been a week or more since I notified you about shipment, please check with your Post Office. If I receive an attempted delivery message I will email you. If you don't pick it up after a couple of attempted deliveries it will likely get returned to us.

All packages are marked with the international Harmonised code for Reduced Scale Model Kits - HS950320.

The total price includes tracked parcel postage to most places in Australia, New Zealand, Canada, the US, UK or Europe.

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