Sloping Off - September 2002

Magnet Tilla
An Electric Conversion of the Flair Magnatilla by Neil Longman

The Project
Well it's that time again for your Activities Sec. to convert another smelly kit to sparky power. This time around I have chosen a tried and trusted kit from the Flair Scout Series, namely the Magnatilla. If you are not already familiar with this kit, it is loosely based around the WW1 German Eindecker.

What's in the Box?
The Magnatilla has been upgraded over the years and now features a CNC cut Liteply & balsa front section for the fuz with a built-up wing also now with CNC cut Liteply and Balsa. The rear of the fuz and the tail feathers are unchanged, using the same open structure of stick balsa. Standard hardware is included with the kit, with the exception of wheels (which are sold separately). Also a Vinyl Maltese Cross decal set was included, which I will discuss later!

What's not in the Box?
Well, as mentioned above, the WW1 style wheels are not included. These are quite pricey and very heavy - not ideal for a sparky conversion, but I am glad I used them in the end. Other items can be purchased for the Magnatilla as well as the other kits in the Flair Scout Series. These are machine guns, pilots, bullets, dummy engines, and closed loop rudder and elevator systems, complete with compensators. I added all these items to my model for that extra detailed look.

Building
The more modern format to the kit makes the Magnatilla a very easy build indeed. The wing is self-jigging and can be built very swiftly, the CNC front section of the fuz also. The rear section of the fuz is built and pinned over the plan in the traditional way. A word of warning here is that this part of the fuz is too wide to marry up with the front section of the fuz, so some filling and adjusting will need to be done when the two fuz sections are joined. This is an error in the plan and Magnatillas have always had this flaw. The tail feathers are built in the same way as the rear section of the fuz.

Modifications for Sparky Power
Very few, really. The only changes made to the model were a false floor for the flight packs and changes made to the firewall for sparky power.

Smelly Weight & Power to Sparky Weight & Power
The Magnatilla is designed to fly on .40 size two strokes, or .50 size four strokes and should come in around the 5 to 5.5 pound weight range. Some quick calculations using our tried and trusted two cells per pound and one for the pot, gives us a model which should perform well on somewhere between 12-14 cells and should weigh around 7 to 7.5 pounds. Power train would need to be around the 700 size motors. Micro radio gear to be fitted using the normal 15 gram size servos should shave around 7 ounces from the AUW.

Motor and Cell Choices
Originally I was going to use a Plettenberg 290-30-13, direct drive throwing a 12 or 13-inch prop, but unfortunately due to delays, (no fault of Gordon Tarling's I might add) I had to plump for a slightly less powerful and ultimately heavier and more problematic power train. A Graupner speed 700 Neodym motor was chosen. This is an excellent motor for the money, but is useless without a gearbox. I had a Robbe planetary box handy which has a 3.7:1 ratio, so after much playing with Motocalc, 14 cells and a 14x10 Zinger prop were selected.

Wiggly Bits
Four SD 200 15 gram servos, one Kontronic Sun speed controller, one GWS 8 channel receiver, all very lightweight and excellent products.

Finishing
The model was finished in Antique Solartex, a superb covering to work with, having a good shrink rate and does not wrinkle. The vinyl Maltese crosses however are not so good - they just won't stick down onto the curved surface of the wing. If anyone has the answer to this problem I would love to know before John and Lionel judge this model for its finish in the Autumn! The dummy engines are easy to build, just like any other plastic kit that we have all built over the years, and the same goes for the machine gun. The pilot has to be joined and painted and of course must be fitted with a flapping scarf! I also added some rigging wires to the wing, made up from leftover close loop wire.

Flying
The Maggie was test flown at Kings Park in June and flew very steadily and slowly - just how I wanted her. The first flight was flown with no coupled rudder and the model certainly needed some rudder in the turns to keep the tail up. On the second flight I used coupled rudder (whoooops, don't tell Mr Morris, that's me cheating again using those damn computer trannies again!) and this improved her positioning in the turn. The flight times are only around 3.5 minutes as I am currently only using Sub C 1700mah packs, but this allows for a safe go round if required and a taxi back. I will upgrade this model to 3000 MNiH cells later in the year and this should give a good safe 5.5 minute flight. Unfortunately on the second landing the bungee system on the undercarriage failed and prevented any further flights. This was only a rubber band system and was not up to the job - the same thing happened again at the Winchester Fly In and also this time broke the prop, thus ending the Maggie's flights there, too. I have since modified this with 5mm shock cord from our local camping centre and this is now proving to be very successful.