Electric WOT4 conversion

Hi all,

I'm in the process of putting together a Ripmax WOT4 and converting it to electric having got bored not being able to fly my lighter foam planes on those windier days.

I've mounted a Turnigy Aerodrive SK3 5045-500 and am thinking that 13x8 on 6S 5000mAh is the way to go. I'm getting 2300g static thrust at 26A, 20V, 520W although that was measured with a couple of 3S 2200maH in series. Model weight is coming in at around 2500g, so, just over 1:1 on static thrust and around 91W/lb.

I'm hoping for something I can learn aerobatics on, so I'm not after unlimited vertical.

Have I pitched it right?

Thanks in anticipation!

Alex.

Firstly, the setup should be fine but you won't need a 5000mAh battery. Also, your 2200 batteries must be shot because the figures you're getting are very low. I'm using the same motor in my Wot Trainer and pull just under 40A on a 13x6.5 using a 6s 3000mAh 20C battery.

Also, FYI, Chris Wild has just done a WOT4 conversion using the 5045-660 on the same 6s 3000 20C battery and a 12x6. This pulls about 60A and although not fully tested, I think this will give a 10-minute flight. Your 500kV motor will definitely fly for longer. If you're determined to have an even longer flight you could go for a 4000mAh battery, but a 5000 will be pushing things space-wise and it is possibly adding weight for no real advantage unless you are flattening the batteries every flight.

Thanks Mike - sounds like 3000 is the one to go for. No surprise to learn my 3S batts are shot. They've had a fairly tough life.

I'd seen on the forum that Chris had done the WOT4 - thanks for posting the details.

Hi Alex,

This plane was suggested to me because although my 48" Extra is wonderful to fly in perfectly calm conditions, it becomes less fun in 10mph winds! So I wanted something that could punch though the wind to allow me more flying opportunities, hopefully the Wot4 will be able to do that.

Due to my slightly over thinking over building/converting of this plane, I think I'd struggle to fit anything much bigger than the 3,000mAh 6S 20C in the limited space I have, but hopefully you'll have more space as you'll have done a better job of it!

I've just put on a 11x7 prop on which will drop the current draw to somewhere just over 50Amps, the 12x6 had decent power so it'll be interesting to see what performance drop this prop will have. I appreciate you've got a different KV motor so this probably isn't much use to you.

It was great fun to fly, but having only just got my white card it'll be some time before I'm doing any serious acrobatics with it, Mike has only just got me started on loops and rolls last week.

All the best,

Chris

Hi Alex,

I also meant to ask where are you putting the speed controller and receiver battery if you're using one. My speed controller has ended up on a shelf under the 'windshield' and the receiver battery is sandwiched between the flight battery and the side of the fuselage where the fuel tank was intended to go. I found the stiff wires on the motor to be a right pain to work with in the tight confines of the fuselage.

All the best,

Chris

I wouldn't bet on my efforts being better than yours. Sounds like we're in a similar position. I got my white card at the beginning of last season, but I've been teaching myself to fly for 3 years or so in farm fields, so lots of bad habits. I've been flying (and crashing) a hobbyzone supercub (now 4ch), a Riot, an MX2 (from Kevin I think - at the club auction) and a HK T45. The MX2 is reasonably weighty, so probably could handle the winds, but I think I'm running before I can walk, hence the WOT4.

I intend to mount the ESC underneath the motor mount and to put a cooling scoop in the cowl as recommended on the Chris Foss website - that should resolve the stiff wire issue. I'm going to use a seperate 5A BEC instead of a receiver battery, so mounting that should be fairly simple.

How have you got access to the battery? Wing off or a hatch? I'd prefer a hatch, but can't decide whether to go for a top hatch or a bottom one.

Did you need to add any weight to achieve a good CofG?

Cheers,
Alex.