No wonder Bobcats are so popular, that’s one mean looking machine!
Whilst trawling around the shed and checking over some models for the coming season, I stumbled on my YT Twister which had given sterling service for a good four seasons now. Looking over the airframe I decided it was time to retire the model but then came the dilema – what to do with the electric running gear installed?
I spent a good two weeks reading through the ads in RCM&E and surfing the internet before deciding on a new model. I knew from the experiences I’d had with the Twister that I had quite a powerful setup in the 41/20-14 AXI motor tied to the 5s 4300mAh EnErG Pro Li-Po pack, the Twister weighed in at 6.5lbs and had enough power for some very energetic flight. I used that weight as a benchmark figure to work with knowing that the motor/ESC/Li-Po combination was equivalent in i.c. terms to a .46 two-stroke to a .65 four-stroke, so a model with this motor sizing recommendation on the box would be about right.
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I’ve been a fan of fast jet type models for a while although unfortunately my wallet isn’t big enough for real turbine power so pusher-prop or EDF fans have been my only options. With this in mind the Bobcat 50 fitted the bill perfectly. Not only that, but with its twin boom setup, GRP fuselage and fixed or retractable undercarriage option, it certainly looked the part.
Don’t throw away those i.c. motor mounts if you switch to electric flight – you never know when they’ll come in handy.
Converting this model did not seem to present too many problems but some challenges did take a bit more time to overcome. I had decided at an early point to fit the fixed undercarriage as I fly from two grass strips one of which has an annoying habit of eating retracts, so the fixed undercarriage regrettably went without saying.
The next thing that would present a little problem was the motor mounting. The Bobcat is designed for i.c. and the tail-end of the fuselage has a purpose-built mounting area for a ‘pusher’ i.c. engine. Trawling around the internet forums gave me some ideas and I spent an hour or so digging through my spares box in the shed and found a suitably sized i.c. engine mount. This I then adapted to take the AXI radial mount. It’s easier to look at the photo to see how I did it.
This model takes 7 or 8 servos depending on whether you go for retracts or not. I fitted Futaba 3003’s in the wings and GWS mini L servos in the booms – two for the elevator and two for the twin rudders, finally a Futaba 148 on the steerable nose-leg. All these were hooked up to a JR900s 9-channel PCM receiver. This gave me one channel per servo – I could have done it all using Y-leads, but having the available channels on the receiver makes everything easily adjustable. Using a spare mixing channel on my transmitter has also allowed me to have the nose-leg steering switchable (on/off) to make ground handling easier whilst reducing drag a little in flight when the steering is switched off.
Ready to rock and roll….
Flying this model is the proof of the pudding, and the first flight was a little interesting to say the least. I had expected a fast model from the off and expected landings to be on the fast side as well. Lining up on the runway for the first flight, I opened the throttle wide and she tore off down the strip but much as I tried, the nose would not lift. I chopped the throttle and managed to slow her enough for a fast turn away from the rough grass at the end of the strip. I taxied the model back and lined up for another blast, this time the nose lifted and she climbed out at about 45-degrees.
I turned for a downwind leg and she kept climbing, five clicks of ‘down’ halted the climb and she settled for a couple of circuits. The Bobcat was certainly no slouch and flying big jet style flying suited her best. After four minutes or so, the motor cut just after a pass and my first concern was would it make the strip? My concerns were unjust as the glide rate, whilst fast, is superb.
Back on the ground, I lined her up after checking the pack and gave her another run up the strip, again she lept into the air much the same as the last flight but again the motor cut just as the model climbed out. luckily it was high enough to fly a return leg and land.
Up and away line a scalded …er…cat!
I thought these flights were a little short lived and it turned out the ESC was overheating so cooling holes were needed in the model. I also completed two ground runs on a larger prop and found that she accelerated faster so I stuck with the new 12x8APC-e.
On the bench at home I noticed there was a little up-thrust on the motor and the C of G was a little far forwards, so with these put right and some cooling holes cut, I popped down the field the following week for the next batch of test flight. This time round things were much better, the take off was a lot shorter and she felt alltogether more settled in the air.
The roll rate is very impressive and a reasonable amount of vertical power is available on my set-up which is about ‘middle of the road’ for the model. My Bobcat weighs in at 7.64lbs so it has a reasonable 100watts/lb power to weight ratio. I do normally try to squeeze a little more if I can but this is a jet-style model and is not intended for 3D flying so it will suit me very nicely.
Fast and jet-like, what more do you need?
All in all this is an excellent model for the relatively small £89.99 price tag and those with a little experience and a 5 – 6s Li-Po set-up kicking around the shed will love it. What’s more, it’s easy to convert to electric power without too much fuss. It has no nasty vices and I’m as pleased as punch with it – for me this has been money well spent.
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