I acquired this AcroWot from a club member who bought it from our late club membership secretary. It is in pristine condition and had minmal flights. Simon the original owner built it for electric power with a SK3 5045 500Kv motor. Running on 6 cells with a 12 x 6 APC E-prop. At the time of this article these along with many other of the "Wot" series have been on back-order for ages, although there are plenty of the foamie versions.
Anyway, realising that I miss the sound of a glow engine, especially four strokes I was looking for an airframe to drop my ASP 80 FS into for a fun flyer and this Acrowot came along just right. Although I did have visons of fitting a brand new Jen 91 but the cowl may have to be hacked to death. Anyway, being built as an electric that meant the cowl had not been cut. However, it later came to pass that the underside of the fuselage where you find a laser partly cut hatch position this model must have been a Friday job because after lifting the film it was not there!
The motor and ESC had been fitted as per the manual so no problems there but unfortunately the battery tray had been hacked a little but I can solve that minor issue. After removing the motor complete with the mounting and the ESC, I made the first look at fitting the ASP engine which was still on it's engine mounting. It had some time ago come out of my Wots Wot (see that article) so should in theory bolt on to the Acrowot firewall as most of Chris Foss's designs use similar layouts but this was not the case here if RipMax had anything to do with it. Two of the mounting holes lined up but the two lower ones were about 5mm out. After some thought I decided to open up all the mounting bracket holes slightly to give me some leeway but still enough so I had to redrill two holes and great fun getting the spike nuts back on the firewall, especially with my big hands and the small tank aperture (former 2). With the nuts fitted I could now temporarily mount the engine. As I had some idea of what cowl cutting is needed (reference the Wots Wot original) to allow the cowl to fit round the engine I started on the cutting. Probably nearly an hours work, bit by bit until it fitted nicely.
What else do I need? Ah yes, a fuel tank. Rummaging through my tank store it appears I had thrown out the Wots Wot tank which was a shame as you really have to use the Chris Foss/Ripmax tank due to its shape. After spending some long net surfing time I found one in stock on Ebay. These tanks are also on back-order so lucky there.
A few days later it arrived and I could now fit it. Not so simple though! Although former 2 is precut for the odd shape the tank slides through but falls inside. Well! It did not in the Wots Wot. After some scribbling and musing I decided to glue 20mm tri-stock balsa pieces in four postions on the inside of the former. With a little sanding the tank now slides in neatly and the tank neck now sites securely in the firewall. The back of the tank just sits inside the former by 10mm. No problem there because I planned to use the battery tray to hold it in place anyway. With that problem overcome I removed the tank, made up the fuel in, exhaust pressure and fill tubes and fitted the Tygon fuel lines. Pulled these lines through and slide the tank into position.
With a little repair mod on the battery/receiver tray I glued a piece of 1/4 balsa tri-stock to the forward edge. When the tray is screwed down this also hold the tank in too. The battery tray has the Nimh pack forward and the receiver will sit on a foam pad (anti-vibration) at the rear. The tray is screwed down on Simon's balsa pads which were a bit rough n ready but I could not remove and replace them as they appeared to be glued with Gorilla glue.
The landing gear is still OEM so I am going to paint it white just to be different. Wheels are okay as standard but I may fit spats if I can find something suitable in the cast offs cupboard. I had some decals laying around so a bit of customisation to try and distract from the standard acrowot scheme.
Achieving the C of G. Simon had 325 gms of lead when it was electric. I have 140 gms on the firewall and 75 gms on the engine mount and factoring the half tank of fuel I am virtually there as to the Centre of Gravity.
March weather is unsettled with high winds, random showers and chilly at present so a maiden flight is on hold. There will be an update on it's first IC flight so check back later.
Update:
Maidened at the end of March. First flight engine still runs perfectly considering it has been laying in the corner of the "hangar" since being removed from the Wots Wot. Prop is 14x6 APC and it flew quite fast and pulled up well in vertical climbs. Being a rather short fuselage it reacts quite quickly in the turns. Ten mins of varying throttle and less than a 25% of the small fuel used. I may try a 13x7 APC and a Master Airscrew 13x6 to see if there is nay improvement (if any needed) in performance.
Only issue on the first and second flights I noticed that the pressure line from the muffler kept melting so both flights at the final citcuits virtually had no pressure feed as such. Unbranded tubing! Replaced with branded silicon 3/32 tubing.
