After owning a couple of good light 3D capable models for some years I felt I had reached the edges of their performance envelopes and I wanted something better. A trawl of the internet suggested that one of the better things was the Sledge. The Sledge is part of a line of profile models developed by Morris Hobbies in the USA. It has a wingspan of 46.5 inches Engine range 40 – 53 2st. 50 – 72 4st. I tracked down a kit at Ansa who are in Wales and asked for a light one.

I opened the box and started building on Saturday afternoon and set to. The parts were all laser cut and the fits were excellent. The wing ribs come with tabs on but as many of these had become detached I made sure I had the correct tabs on the tip and centre ribs, then used straight leading edge and trailing edge stock as a jig. The wing design in terms of its construction at the CS made me a little uneasy but I built it as per the plan as there was nothing on any of the forums to suggest that wing strength was a problem. By Sunday evening the wing, fuz and tail feathers were done. The only thing which needed fettling was the wing to fuz fit. Had I started on Friday I would have gone to my model shop on Saturday and replaced all of the strip balsa and some of the sheet with lighter stock but more on this later. All the hardware supplied was first class with beautiful bushed metal horns, all the material for pull pull linkages and a Sullivan tank. There were minor niggles, I had to drill my own holes in the U/C legs and all the nuts and bolts are US sizes. I covered it in Solarfilm, using solid fluorescent orange on the underside to contrast with the white and metallic green topside. I installed five standard 148 size Futaba servos and made my only serious mod in that I dispensed with the right hand open wing bay and fitted two servos into the central rib. I also chose to mount the tank in front of the wing on the left side as I believe this gives more reliable vertical engine runs in those loooong prop hangs. I had planned to use my 5 year old MDS 38 which never cuts and has the best throttle in our club but a trip to the scales suggested that more urge might be needed. Many of the Yanks are using Saito 72 4st motors but I decided on a West 50 T1 plus throttle pipe. If you go down this route make sure that they understand what you want it for. I think they assume everyone is ordering for a Hype and supply the Hype custom pipe. An APC 13x4 Wide was needed to get down to my clubs noise limit and I was ready for the first flight. Test flight As I carried it out to the flight line I was not confident that I was going to like this aeroplane. I knew that I could have built it 150 to 200 grams lighter and thought I might have a bit of a dog. 10 minutes later I knew that in this model I had the two essential components on any male dog. This is the best medium size 3D model I have ever flown. It will hang, flip, harrier and lomchevak with ease. It can be flown at ridiculously high angles of attack without stalling and the elevator while powerful is not overly sensitive. The rudder is exceptionally effective and combined with the sheer grunt of the West 50 has enabled me to achieve my first ever continuous knife edge loops [7]. There is more to come as I think the plan CG is more than a little conservative. If I built another I would dispense with the pull pull rudder setup with the servo in the wing and mount the rudder servo in the fuz , near the tail with a short push pull rod. I would change the angle of the innermost part of the aileron to allow for more movement. Whinges. 1) I could build it lighter but with the West 50 why bother. I am playing with throttle exponential as it is prop hanging just above fast idle. 2) The ali undercart bends in anything other than a near perfect landing. 3) The only flying characteristic to cause problems so far is the significant roll couple when rudder is used for knife edge flight and I think I can mix this out on the transmitter. Engine comments. The West 50 TI could be hand started from the off. Unusually the carb. came with the idle needle set a touch lean but this was an easy fix. It has had about 10 tanks through it as I write this. It is throttling reliably and the exhaust is starting to clean up. The engine turns the APC 13x4 with ease and allows for continuous verticals on less than half throttle. It would fly well on a decent 46 – 53 and if you built a light one a good 40 would be fine. Update. I have got about 50 flights on this model now. The only problem areas are the tail plane to fuz joint, this needed reinforcing with ¼ triangular fillets and the aileron servo mounts which needed reinforcing. Both problems were probably caused by my exploration of the high speed high G maximum control deflection edges of the flight envelope. Yes, I know I am a hooligan.

The Sledge can be cruised around very slowly, at ridiculously high angles of attack, in both normal and knife edge flight. In fact, in my opinion, it contravenes some fundamental laws of aerodynamics. If I lost this model today I would build another right away and use the same engine, it is the absolute dog’s b*******.

Article by John Duncker for Bumpy Green Model Aerodrome
October 2004