Watersnake

[killerbob]

Hi all..

Starting this thread ..... to be honest because I need input ...

Boat is MN Products Watersnake - 55 in V hull

Motor: TP 5860 - 5Y - 600 KV
ESC: Swordfish Pro 300A HV Lite
Drive: Arrowshark SR512
Rudder: Arrowshark X-Pilot
Trim: TFL Radioadjustable Trim Tabs
Tun-Fins: TFL (will try without)
Lipo: 4 x 6S Zippy Compact 5000 mAh - 60s (12S - 10.000 mAh)
Prop (first try): Octura x460/3
Servos: Waterproof Sawö 20 kg
Radio: Graupner HOTT - with 3 axis gyro-stabilizing and Telemetry
Misc: Graupner Electric Air Module (meassures Voltage, Current, Rpm and temps)
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[killerbob]

A few more pictures from initial construction... Carbon Fibre / Kevlar cloth added. Drive and Trim Tabs installed


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[killerbob]

So .... here comes my trouble

I am having trouble with the layout...

Placing the motor in the middle and 2 packs in front and 2 packs behind the motor is the best layout when it comes to stress on the flex and my ability to adjust the CG ... Anything between 28 and 32% can easily be obtained simply by moving the front packs... BUT the trouble starts when trying to mount the ESC .. The water-cooling inlets on the esc will face forward, and long lines will be needed. Also Cabling to the Batteries and the ESC/Motor will be difficult with relatively long cables

Placing the motor as far rear as I can will give a more steep angle for the flex .. Will it Work ??? Also Placing them in length direction will limit the CG adjustment to 30%+ 28% is no go ..

Placing the batteries across the length direction will get 28%-32% adjustment back - but because of the V-Shape of the hull the weight will move aprox 1,5 in UP .. I have "heard" that this hull really likes ALL weight as low as possible..

What would you experts do here ???


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[Doby]

My preference for layout is with the 2 packs in front and two behind the motor, that allows for a slightly longer stuffing tube and less bend in the flex cable, also allows for the two front packs to be moved forward if required to help level things out when running.

[killerbob]

Would the layout shown in the pic below influence handling ??

My big problem is where to put the rather big ESC... Just there would be ideal for short cables to the motorIMG_6747.jpg

[Doby]

Any layout has the potential for affecting handling..generally try and keep everything as low and close to the centerline as possible.

As for the esc, most simply get mounted on top of the motor, your mount has a plate for just that.

[Doby]

Also, consider adding stringers in the hull to mount the motor to that will help distribute the load (weight and power of the motor) over a larger area.

[Roy Van De Sande]

The standard motormounts you can buy place the motor too high in the hull. In my boats I can't put my finger under the motor when they
are mounted. A custom made motormount places your motor lower in the hull allowing the batteries to be placed in front of the motor and the esc on the left side of the boat (left side = other side than were your rudder is mounted). Something like this for the motormount: IMG_0551.jpgIMG_0600.jpg
Just add a support ring on the back of the motor. Something like this: http://mbp-rc.de/Alu/GFK-Drehmoment-Stuetze-56mm_1

[killerbob]

Slow progress here as I am awaiting a box of stuff from Offshore Electrics to get much further. Sadly it seems to be stuck in customs

I am so tired of hatch-tape that I have decided to waterproof like the IC guys do. However I haven't got room for "standard" radio boxes, so I am building 2 smaller ones from 1 mm Carbon fiber plate (3 mm clear polycarbonate in top)..

The pics shows only the front plate where I have made connections to the motor and water-cooling to the esc. On top of the ESC you see the electrical module from Graupner. It is a bit underrated if I wanted to use the full potential of the motor and the esc.. It can stand 150A continuous and 300A for 1 sec... However I believe it will be more than enough .. 150A on 12 s under load is 6300w - And peak will be 12.600w (1sec). I think that will be enough for this boat... We will see. If it is not - the module can easily be removed.. I actually would have preferred the UnisensE 280A from Sm-Modellbau - but that sensor does not have any temperature sensors. The Graupner module has 2 ... The thin leads are connectors to those sensors. For starters I will have one sensor on the motor and one on the ESC ...

My servos ar watertight and will be left out... I will build a small box for the receiver and even build boxes for the lipos... and then - NO Hatch Tape !!

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