Recent content by MitjaJ

Moment of inertia is not something that you can move foward/back - that can be done with CG. Moment of inertia just tells you the "arrangement" of mass in a volume regarding to a fixed origin (for us this is the CG). I've seen those Japanise riggers with the motor way back - one would have to...

I used Solidworks. The difference between moments of inertia is around 2 (I've checked it again.) Old = 80175179 g/mm2 New = 38178657 g/mm2 Some pictures:

One thing that I noticed that affect stability/ride of a rigger is the moment of inertia of the boat. I've made two electric outriggers with the same outside dimensions. With the first hull I didn't put much attention how the gear was placed inside the hull - I laid everything so that it was...

No I have no actual experience using 2.5 mm wire drive. I use 2 mm on my hydros with no problems (1.8 kW peaks from logger), and guys here had no problems using 2mm wire drives on 8S1P saw setups. I made some calculations (see attached file) and I believe that a 2.5 mm wire would be enough...

Really nice boat ! For shaft vibrations - a custom made wire drive usually runs vibration free. For the power I would use a 2.5 mm wire drive, best would be to use ball bearings in the strut. The shaft and clutch must be made very precisely machined by a skilled man on a lathe (+grinding/EDM...

I also work all my BeCu props under a lot of water/fluid that will trap particles - this is the only way to safe handle berylium - using a dust mask will prevent dust to enter your loungs but the workshop will be still full of dust that can cause problems later in time. Even tough the alloy...

I made a new turnfin adjusted the angle of attack and the boat now turns like on rails. Thanks for the tips.

Anyone can help me setting up my turnfin ? I was usualy using a straigth turnfin on my outriggers but now when the speeds are gone up on my new (my design) electric outrigger (4S1P, 2200 KV motor, running an Octura X445 or Prather 225). I'm having problems preventing the boat from flipping in...

I never had no problems with curing - don't use too much heat - just enough to make the epoxy flow easier.

No need to thin. For the first coat I just use a heat gun/hair dryer and then wipe the excess of with a paper towel. I then sand using a sanding sponge, and apply another thin coat of epoxy. I then sand again using a very fine sanding sponge, until I get the required finish.

It looks amazing. :o It seems that the CG is way back, on the straigths the boat seems to ride only on the prop, the sponsons are not even touching water. I wonder how does it handle when the water is rough.

How long is your turnfin ? - I had the same problem with an electric mono, solved it using a longer turnfin (the first one was too short and too narrow). Even full throtle turns are no longer a problem now.

The motors we use in our hobby are different than AC motors. AC motors are induction motors (have no magnets) and operate quite differently and have different rpm/torque characteristics. Our motors are brushless permanent magnet DC motors, they are BLOCK COMMUTATET (full current is applied on...

Do not confuse DC brushles (block comutated) motors with AC motors. The number of motor poles says nothing (or little) about the amout the torque the motor will develop. Usually high pole count motors are used for low rpm applications (no need for transmissions) , but cannot be used at high...

For gluing wood polyurethane glues work very well. The bond is as strong as epoxy, waterproof, lighter. There is also no need to mix two components.