Aerobic 020
kit review by Trevor Hewson

I bought this kit at the 2001 Sandown model show, from the FMK models stand. I always have a browse round this company's offerings if only because at one time they were the only reliable source of thin odourless cyano! This year though, with my new interest in indoor flying, my eye was caught by a couple of neat little models on display, one of which was the Aerobic 020.

The name presumably derives from the little Cox engine shown on the plan and the fact that 'Aerobatic' was too big a word for such a small (22in span) aeroplane. The model sports a fully built up symmetrical wing, an aluminium tube tailboom and built up tail surfaces and looked ideal as an indoor aerobat. A peek inside one of the kits showed the wood selection to be pretty good, so I parted with my £18 and headed back into the melee. To my surprise, I was promptly called back and presented with a pair of tiny wheels (they had been out of stock when the kits were packed apparently).

Back home, first step was to unfold the plan and see what I had committed myself to. For such a simple aeroplane, it seems to have benefitted from a lot of brainpower and experience - the plane was apparently designed by Peter Miller and redrawn by Pete Kent for the Miniature Aircraft Factory in 1996 and modified in 1997 by R. Hesketh (FMK Models). Well, it was about to be modified again by yours truly, if only to tackle that inescapable challenge of electric modelling, namely where to put the battery.

Offering up a 7 cell 'Pico Stik' battery indicated that the neatest home for it would be behind the leading edge. This would entail moving the two inboard ribs out a bit and also cutting away a big chunk of the central 1/4" balsa piece which formed the central rib and forward fuselage. The biggest worry though was whether the model would balance with the battery in this position, because there would be very little scope for moving it around. After considering and rejecting various more flexible, but untidy, strap-on options, I decided that I really had to go for the 'in the wing' option and hope that I could adjust the c.g . by positioning of the servos and motor. It was now a case of building as much of the airframe as possible before having to finalise the position of these, too.

Having resolved what to do with one electric flight bugbear, my attention now turned to the other one - weight! The quoted weight for the i.c. version is 7-8oz. Doesn't sound a lot, but I know my mini IFO weighs only 4oz - and has nearly double the wing area. In fact, at 8oz, the wing loading of the Aerobic 020 would be nearly 7oz/sq ft compared with 2oz/sq ft for the mini IFO - oh dear! Up until this point I had been considering fitting a rudder but, faced with the need to put the model on a diet, this idea bit the dust immediately. Next on the lightening list was that 6mm aluminium tailboom. A piece of 6mm carbon fibre tube was substituted reducing the weight from 12g to 5g. Then I spotted a piece of 5mm carbon fibre tube which seemed plenty strong enough and took the weight down to 3g.

There really wasn't much more to be done on the weight front. The piano wire undercarriage was replaced with a couple of carbon fibre rods and the front fuselage side cheeks (which were really there to support the radial mount for the Cox motor) were omitted, and some lightening holes cut in the ribs.

The build itself was straightforward and, for modellers of my vintage, quite nostalgic - apart from the use of cyano instead of balsa cement, of course. Trial balancing, with various bits taped on, indicated that I could mount the servos a little further back in the wing, so shortening the pushrods a bit - and shorter pushrods can be a bit thinner, so a few more grams were shed.

Covering
Normally, choice of colour scheme is a source of delay and uncertainty for me, but a peek in my box revealed enough Litespan leftovers from the Lazy Bee, so that was one decision easily made.

Fitting Out
I already had in stock a couple of FMA micro servos and, having been impressed with the Potensky motor in Neil's Little Party, I ordered one of these for the Aerobic. The tried and trusted GWS receiver and speed controller combination made up the equipment complement and this was all duly installed, leaving the motor until last, just in case the nose length needed some adjustment to get the balance right.

Then the moment of truth - onto the scales with it. A quarter of an ounce shy of 6oz with an 8 cell 50mah battery, a quarter of an ounce over with a 7 cell 250mah Perkins pack. So I was well pleased that it came in under the recommended i.c. weight, even with the heavier battery on board. Time for the second moment of truth, then!

Flight Tests
As luck would have it, on my next evening outing at the local field, the wind dropped off as the sun went down so, with twilight approaching, Jim pushed the Aerobic 020 into the air. It flew from his hand without drama and just as the wave of relief and delight was washing over me, Jim laughed and announced 'That is not an indoor model!'. At this point, the model was only halfway round its first turn, having been airborne for all of two seconds and I was shocked. 'Why not?' I said as the little plane zipped smoothly past us. 'Too fast' came the reply.

So, after a few loops and rolls, round I came for a slow pass 'What's wrong with that?' Okay, there was still a breath of wind helping me to slow down, so I sighted up my imaginary flying hall and set about some pseudo indoor flying - and soon concluded that, sadly, Jim was right. I just about convinced myself that it would fly indoors but, to be honest, it wouldn't be anything like as much fun. Like most symmetrical wing models, if you slow up too much, the Aerobic suffers from aileron reversal (i.e. the downgoing aileron encounters higher pressure air than the upgoing one and so generates more drag, so 'left aileron down' turns the model to the left, which is the opposite of what we normally intend!) Outdoors this is not a serious problem because firstly, it is easy to keep the speed up and secondly, if the ailerons don't immediately produce the desired effect, you just ease the stick forward a bit, build up speed for a few yards and then the turn will start in the intended direction. Indoors, though this is not an option, in fact the normal drill for warding off contact with an approaching wall is to haul th nose up and bang the rudder over - and you will remember, I haven't got one of those!

Conclusion
So, as an indoor aerobat, the Aerobic 020 looks set to be a non-starter. However, as an aerobatic park flyer, it promises to be a lot of fun. For this role though, I will be swapping those dinky 1/2" wheels for some GWS 2" ones which will also allow me to change to a slightly larger prop in order to improve the looping performance. Rolls are very fast and, as you would expect with a symmetrical wing, inverted performance is great. The relatively high wing loading (by indoor standards, anyway) helps it to handle a bit of a breeze. And now I don't have to worry so much about the weight, I might retrofit that rudder, after all.....