Wots Wot once an electric then a four stroke glow and now - electric again? I have flown this Wot Wot for years after I first acquired it when the model was released. It was then powered and built as per the instructions using an Emax GT 3526 motor which quickly got replaced by a SK3 5045. Running on five cells it was a joy to fly although you had to power it all the way to touchdown, it did not glide and too little airspeed and it would drop like a brick. Two of us found that out quite quickly. Way back though in the last decade I decided it boring as it made virtually no noise.
Off came the adaptor and the firewall was reconfigured for the ASP 80 four stroke. Pulled it extremely well, reliable, easy starting, a nice pleasing engine sound and good on fuel economy. However, in recent months I got fed up with cleaning glow oil of it and anything else it came in contact with. As it was now the only glow powered model left in the hangar, the Curare had earlier been converted back to electric recently, I finally decided the Wots Wot was going to get the same treatment. I had tried twice to sell it on via BMFA classifieds with no joy! A fellow member who built an excellent one from the kit struggled too!
Not wanting to spend any serious money on the conversion I planned ahead for the job. First off I located a new cowl on Ebay and after sifting through my stores for a suitable motor with nothing there in the 50mm class I bought a 5055 600kv from 4Max, the latter the most expensive layout so far. The Cowl would be only £14.00. Speed controllers were not a problem as I had numerous YEPs in 80 and 60 amp classes.
With the old cowl off I removed the engine complete with bearers. With the wings off I pulled out the fuel tank and lines. At this point I weighed the engine and made a note of it because the motor would be less than half that weight. tHe glow fuel had soaked in over the years so a dry out was needed. The covering too at the front end was lifting so a partial recover would be needed too.
The motor is fitted on stand-offs their length cut down to ensure the motor drive was just a few millimeters forward of the cowl. The motor X mount was used as a template to drilling the firewall.
Following a similar design plan as per the original instructions for battery placement I modified the hatch area to take a six cell 4000 maH lipo pack. I made up a battery guide floor with 3mm furniture grade ply. I also made up an over length battery plate (to allow for mods later). After dry fitting the battery guide floor and the battery plate loaded with a 6S 4000 maH lipo (weight 563 grams) I see I am on the right track. The battery just comes up level with battery hatch. Therfore any 6 cell of lesser capacity will also fit as an option.
Bearing in mind I needed a fair bit of weight up front for balance I decided on making up a bracket on the underside of the battery guide floor and fitting the receiver/redundancy battery (105 grams) underneath up forward as much possible.
With motor mounted and the ESC strapped on to two of stand-offs I was able to make some small cuts into the replacement cowl to allow for airflow and clearance for the battery hatch. In this "game " you have to think at least two steps ahead rather than having to "cock-ups".
With the cowl fitting okay, I move back on the the battery plate. The battery guide just sits below the recess in the firewall held up by a block of Obechi chamfered to allow the sloping angle of the battery floor. The guide plate front edge was given another small layer of ply so I could embed a 3mm captured nut. The nut will take a screw which will hold down the battery plate. Notice that the plate has a larger hole to drop over the head of the screw and the final sliding in of the battery the screw will secure the plate.
The hatch was given a little tongue so that slides back into place to cover the battery (and secondary security) and lock down by some small servo arms. The Wots Wot appeared to balance nicely but I would only find out on it's maiden flight.
I recovered just the front section with some light yellow Oracover. I did not go overboard to detail as the model has various patches and Oracover does not appear to use the same colours as whoever makes these things in the Far East.
Flight Test
3rd July, Sunday a warm although later became a bit breezy with mostly sunny clear skies I took it up the field. I had reset all trims to neutral although I do remember where they were with the ASP 80 engine. After a few circuits and some trimming I gave it a few aerobatic sequences and after flying for about 5 or 6 minutes I landed. Guess what? Trims were back to virtually where they were previously so CG was good. Battery still 65% capaicity left so pleased with my effort. So, Wots Wot has gained some more flying life after all. Now just unplug battery, pick up and slide into the back of a hatchback car for aquick getaway and no wiping, cleaning!
* Props tried were 12x8 APC-e too small. 14.x8.5 APC-e Have to go easy on full throttle. Will happily fly on 3rd throttle level.
