It’s time for a Katana. During the competition in Benesov I bought a brand new kit direct from the manufacturer.

Since last year I have been paying careful attention to this model at international events, to see how it performs aerobatics and freestyle. I believe it to be a very good model, but is it better than the Extra 260?? We shall see.......

Unfortunately this is not a Composite Arf plane, where most of the work has been done by the little hands of Thai girls. In this case we have to make the effort ourselves.

We start by attaching the rudder drives. There isn’t much to stick this to, as there is just the wall of the rudder, without a piece of balsa. But just maybe it won’t fall off!

The hood is attached as in the C-ARF models. Use 3mm blind nuts, stuck back-to-front with cyanide glue, and then cover with epoxy-microballoon. A simple and sure method.

In the meantime we prepare the aileron servos. Two JR8711s per aileron will be enough. I am a bit unhappy with the method of attaching the servos (as recommended by the model’s manufacturer) – the servos are powerful and the aileron has a vast surface – but if I try to fly low and slow maybe it won’t all fall apart.

The plexiglass cabin was already glued in; it remained to make the fastening of the frame to the fuselage. This time I didn’t use the method of attachment suggested by the manufacturer, but used the same technique as in previous models. Under the pieces of plywood which were stuck to the fuselage I also glued in some metal washers. This way the screw heads won’t damage the plywood when the cabin is regularly screwed and unscrewed, and the fastening of the cabin will be durable.

Positioning the engine on the firewall – you’ll need a decent ladder with a model this big. Not having any data or dimensions, I positioned it relative to the hood.

Fastening the undercarriage wasn’t easy either – it needed a lot of sanding. I painted it red, because it looked awful. There will still be a masking cover as well.

On a recommendation of Czech friends of mine with experience in building these models, for the elevator I planned to use one powerful JR8711 servo per half. They said that this would make the model lighter and easier to balance. But after two days’ intense thought, I reached the conclusion that I don’t really need a light model, since I wouldn’t be flying it in a hall or only in windless conditions. (I wonder why everyone tries so hard to have super-light models, and then at competitions fill the smoke tank right up – more than a litre of oil, they’d even use two if they could – just to add weight to the model, because there’s always a wind blowing. Particularly in competitions it seems to blow at 5-8m/s.) So I added one more servo for each half. Now it’s great – I’ll be able to execute the most sharp and sudden manoeuvres without worrying that something untoward might be about to happen.

There is never too much ventilation in a model....

There were more difficulties with adjusting the wings – nothing seemed to fit – but in the end I succeeded in getting them to the “O” position.

The silencers and manifolds are from Zimmerman; they are very good, durable and easy to clean inside. The silencers are mounted in the traditional way, on springs, as in all of my models. The silencers rest on four short tubes of reinforced silicone. 

Now we screw on the engine and mount the ignition apparatus, controller and battery. There is no problem here in the Katana, with its ample space, and there will be very good and quick access to these items in case of any malfunction.

Now we need to prepare a shelf for the fuel and smoke oil tank. I came up with a mounting method using four 3mm screws. If necessary, it will be possible to dismount the shelf together with the tanks and the smoke pump in five minutes. I will permanently stick together two pieces of 4mm plywood, under which the shelf will go in, fastened by the four screws. But for the moment I’m off to bed - goodnight.

The shelf is ready – we’ll screw it on at the very end. First the shelf with the Power Box will be mounted.

And this is what the inside of the tank looks like.

The shoes in this Katana are very delicate, so I decided to try fastening them using silicone only. They are placed from above onto the axle and wheels. I wonder how many landings they’ll survive.

The Power Panel is ready, so we fix it in the fuselage using double-sided sticking foam. It can be taken out easily should it be necessary to do so.

Final adjustment of the hood and the cabin.

The Power Panel and the shelf with the tanks are now mounted. The model is ready for a test flight.

The KATANA has completed its test flight! First impressions – it flies the way it should. Compared with my Extra 260 it’s slightly better at 3D figures. It’s more manoeuvrable in the harrier and rolling harrier, but it doesn’t hang so well. For classical aerobatics the Extra 260 is better, as its flight is straighter and more axial. The Katana is a good model for those who prefer freestyle.

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