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.

Hi Alex,

Hopefully these pictures will show you better than words can what I did, but this is my first attempt at anything like this so probably not the best approach.

My motor box ended up a little over built and too big to allow the speed controller to be mounted to it and still get the canopy on:


So I've placed the ESC on a shelf under the 'wind shield', 'accessible' by a hatch/air intake from underneath. I wanted to try and get a bit of air flow over the speed controller:



I put in a battery tray, and have just accepted that I'll have to take the wings off to access the battery, it struck me that due to the size of these 3000mAh 6S batteries, I'd have to cut a huge hatch in the airframe and through several formers to be able to get one in or out. And at least I don't need to turn the plane upside down to put a battery in.




I probably went down many wrong roads, but at the time each decision felt well thought out

I'm very interested to see what you do, and hope you enjoy flying it soon.

All the best,

Chris

Nice spinner, Chris!!

One further note is that Chris sourced some high voltage hitec digital servos for about £15 each...so he runs them directly from the 2s receiver battery. Seems like a good solution and not too expensive. I'm using low voltage servos (because I already had them) and a separate BEC like Alex.

Glad you like the spinner Mike, the white one has [strike]everything[/strike] nothing to do with the fact that I managed to ream a hole at an angle to the back plate on the black one that came with the kit! I just thought it would look better in white and show off the grass stains better

The servos are Hitec HS-5495BH HV, hopefully a good choice, but only time will tell. I do like the simplicity of the power setup for the servos and receiver.

I was getting getting a little concerned that the cowl was preventing any the any air flow around the motor, so this morning decided to cut two air intakes into the cowl, and although the motor isn't in the direct flow of the air I'm hoping enough will be moving past to aid in the cooling. If nothing else I can now stick my finger in and see if it's hot to the touch.



I hope your conversion is going okay Alex.