World Airnews - May 2004

South Africa's Sleek Little Slick - Text by Glen Dell and Tom Chalmers. Photos by Ian Burnham.

It's sleek. It's slippery. It's oh so smooth. It's superb and it's all South African. It's the Aero-Cam Slick 360 designed to take on the world's best in international advanced aerobatics and it will make its world public debut at the EAA AirWeek at Wonderboom Airport, Pretoria, from April 29 to May 1.

And after all the oooing and ahhing of the exhibition is over, it will face its first major test when it takes part in the South African National Aerobatic Championships to be held in East London next month. This is where it will come under the critical eye of the country's top exponents of the art of aerobatics and where it will be judged worthy or not of representing the country at world competition level. Its makers are confident that it will woo even the most ardent pessimist, for here is an aircraft designed with passion and built with dedication by a team of men dedicated to the art of advanced aerrobatics and, more importantly, getting it right the first time.

The Slick 360 was first conceived when it became apparent during the past few Advanced World Aerobatic Championships (AWAC) that there were simply no top class aircraft being built to take over from the trusty old Pitts, Zlins and Yaks.

These wonderful old planes had served the aerobatic community for 25 years or more, and although still competitive in the hands of a highly skilled pilot, were becoming expensive to operate and maintain and deserved to be put to use in a less demanding roll. The brand new multi-million rand Sukhois, Caps and Extra’s were not allowed to be used in the Advanced Category, where pilot skill is the measure of the day rather than the thickness of the participants’ wallet.

This fact was foreseen by some designer / builders who started to produce, in limited numbers, aircraft such as the One Design, Giles series and its derivative, the Cap 222. These aircraft all obtained fantastic performance from relatively little power achieving speeds, roll rates and climb statistics that far out-performed their older rivals. Even with the performance advantage however, the pilots of these aircraft did not achieve top placing at Advanced World Aerobatic Championships (AWAC). In five AWAC events, two were won by Zlins, two by the Extra 230 and one by a Yak 55. The Yak 55 is some 30 years old, the Zlin 25 years old and the Extra, 20. Considering the Extra was a 230 horsepower aircraft (versus the Yak’s 360 and the Zlin’s 300) it had to be doing something right. The last AWAC held in Slovenia was won by a French pilot flying an Extra 230. This is interesting as he did have access to the French teams Cap222 but elected to fly the 230.

NEW GENERATION
The “new generation” 180 to 230 (four cylinder) aircraft were statistically not doing well. The performance of the planes was however superb.

In the case of the One Design, judges complained that it was simply too small. Roll rates were good, but perhaps too good. Normally (or traditionally) an aircrafts’ (aileron) roll rate was perceivably slower than that that could be achieved in a flick roll. When these small, somewhat difficult to judge planes arrived at competitions and did aileron rolls faster (in excess of 480 degrees per second) than flick rolls, the flick rolls were down graded. Rate of roll, beyond a point therefore, was not necessarily an advantage. Simply applying less aileron deflection seems the obvious answer but is almost impossible to do consistently. A healthy balance appeared to be the answer. A slightly bigger aircraft with longer wings would also allow the judges to accurately judge the manoeuvres. A wing design that allowed a fast, easy to (consistently) perform and stop flick, was also important.

The pilots of the Zlin’s and Yak’s were vastly experienced pilots who had literally years and many hundreds of hours flying their specific aircraft type. The winner of the 1997 AWAC went to the USA, borrowed an Extra 230 (not pre-planned), flew four and a half hours practice in it and won! The winner in 2002 had been flying his teams Extra 230 for only a few months.

So – the plan would be simple! Lets just buy an Extra 230. Walter Extra stopped building the 230 about fifteen years ago, supposedly because he could no longer get wood of good enough quality to build the spar. Whatever the real reason, he moved on to produce aerobatic beauties such as the 260, 300, 300S, 300L and the 330. These aircraft were all powered by six cylinder 260 / 300 horsepower Lycomings and were therefore not allowed to participate in AWAC competitions.

A PLANE IS BORN

Since the Laser derived Extra 230 was clearly a winner, we decided to attempt to produce an aerobatic aeroplane base on the 230 but with as many upgrades as possible. To this end Francois Jordaan (an Aeronautical / Structures Engineer) was approached to design a carbon fibre / composite wing. Francois’ design experience in composite materials is extensive and includes that on the world beating Celstar aerobatic glider and Jan Troskies’ fabulous Ravin 500. He incorporated the latest aileron design (poached to some extent from the new Pitts 1-11B), kept the fantastic flick capabilities of the Laser, the size and basic wing shape of the Extra 230 as well as the control system of the 230.

Chris Hattingh, brilliant with hands and general ingenuity (and who works with Francois at AeroCam) was tasked with the overall management of the building project. He was responsible for the majority of the shaping, assembly and supervision. He was helped by Conrad, Ian and the ever suffering “little” Chris who was responsible for profiling and tea making. One can imagine the number people whose assistance was required and all were forthcoming in the most generous way. Thanks too to Chris and Deola Briers from Naturelink who helped in so many different ways – the plane you may recognise from the accompanying photos is named after Deola.

What to call the aeroplane? A well-known aviation personality visited the hangar one day, looked at the little plane and said, “Wow, it’s slick hey?” So the plane was called the Slick 360. Slick because that’s its name and 360 for the Lycoming AEIO360A1B6 (from AeroSport Power in Canada) that powers it.

FLYING THE SLICK 360
And after a (relatively short) while, it was finished. All the CAA documentation and permissions were (very promptly and efficiently) received. Most pilots do feel some trepidation prior to an aircraft’s first flight. The Slick however felt so comfortable and secure that any trepidation was dispelled. I filled up, pre-flighted, taxied out, did a power check and took off.

It was really easy to keep straight and if one stretched their necks, visibility over the nose was as good as a Zlin 50 (i.e. much better than a Sukhoi or a Pitts). The tail could be lifted immediately full power was applied and acceleration with the four-cylinder engine was as good as that of a Pitts S2S. The aircraft flew itself off at 70 miles an hour and thereafter, with a climb speed of 86mph, matched the climb performance of a 360 horsepower Yak 55. Straight and level speed was 195mph indicated and over the next few hours, as the engine loosened up, this increased to 202. Max straight and level speed at sea level would therefore be approximately 220mph which is some 14 kilometres per hour greater than the never exceed or max dive speed of a Zlin 50. Stall speed came out to within one mile per hour of that calculated by Francois (57 mph). Inverted stalling could not be achieved during the first flight as there was insufficient forward elevator available. A one-degree ground adjustment of the horizontal stabiliser rectified this problem. Flick rolls were predictably good while roll rate at some 310 degrees per second was slower than calculated. This was initially rectified by increasing the deflection angle, and subsequently by the modification of aileron components.

Visibility out of the sleek canopy expertly free blown by John McKerchar, an SAA Airbus A340 Captain, was excellent. Approach and landing was straightforward with no Pitts type “pedalling” required to keep straight.

FUTURE PLANS
All in all the little plane behaved beautifully and (apparently) sounded great – not at all like a normal popping four cylinder. This is due to the rather rude looking four into one exhaust built by Sky Dynamics in the USA.

Pre-planned changes on the next aircraft (another four have been ordered with a planned yearly “production” of twelve) include a totally composite tail (no flying wires), increase in total aileron area of 24% to achieve a roll rate in excess of 360 degrees per second (if desired), a ballistic parachute as an option, an adjustable

Kevlar / carbon seat and various bits and pieces that should also be considered options.

The Slick only has 9.6 hours total flight time, and much of that consists of various testing and photo flights. I shall therefore leave judgement of the aircrafts various flying abilities and performance to the SA National Aerobatic Championship Judges in June 2004 (East London) and to the many pilots who’s passion for flying and aerobatics will, I hope, lead them to sit in the seat of this beautiful sleek little Slick.

World Airnews - May 2004

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