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It’s 1530 on 14th November, 2006. I’m lined up for departure on runway 1:6 at Heck Field,
Jacobs Well. The windsock is standing straight out and pointing directly at me. It’s a hot, gusty day
and I’m about to open the throttle in anger.
The tail comes up and the Conroy Sparrowhawk has sky under her wheels for the first time.
Early in 2000, I had decided that whilst the tandem-seat Conroy Sparrow XC had achieved a satisfying degree of market acceptance, the trend was definitely toward side-by-side seated LSAs. No problem. Just take the left and right hand sides of a sparrow XC fuselage, set them up in a jig with 20” gap between at the cabin, taper both ends, lengthen a tailcone by 6” and join it all together. Easy ….
Yeah, right!!
The idea had been running around in my mind for several years, use the same wings, empennage and landing gear assembles, move the fuel from the vexatious wing tanks to a single tank under the seat and right on the CG, increasing capacity to a useful 100lt, design and build a nice, comfortable interior with plenty of leg, head and elbow room, leave enough space behind the seats for a large stowage compartment or even another two seats if someone wanted to build it in the experimental category and bob’s your uncle. Won’t take long.!!!
Right..?
Wrong!!
I suffer from a mild form of benign insanity. I don’t what this syndrome is called but it’s made up of enthusiasm, optimism and idealism, with a liberal sprinkling of creativity, work addiction and determination, all of this focussed directly on my lifelong dedication to aeroplanes and aviation. I’m a firm believer in the theory that there is nothing on earth more powerful than an idea whose time has come so once ones takes hold, I’m driven to try to see if it works. The Sparrow project started off a one big idea and then grew into thousands of smaller ones and whilst this is not particularly debilitating to me, it is infuriating to those who are close to me and those who are waiting impatiently for me to finish the latest creation.
Fibreglass is a wonderful material. After being involved with it for just on 50 years, I still learn something new every day in the workshop. With a little experience, some lateral thinking and knowledge of the enormous variety of high-tech materials which are currently available, one can make anything you can think of from it. You can engineer any structural property you want into any component, from seats to landing gears, from flap hinges to whole wings. The elegant solution is always available.
BUT IT TAKES TIME!!!!
Virtually every part you make, you have to make three times. First comes the plug, made from any suitable material to the shape required and finished to requirements. Then comes the mould made from fibreglass and sometimes in a number of sections to accommodate undercuts. Then comes the part, usually using sandwich laminates and often carbon fibre and/or Kevlar depending on the job it has to do.
In many cases, I look at it sometime later and realise that I can make it better or perform more that one function, or that I simply don’t like it any more and the whole process starts again.
There is another factor here, too. Anyone who presents a product such as an aircraft for sale to the public has a firm obligation to make it as good and safe as it can possibly be. This ranges from aesthetics to strength and safety. There is no excuse for making an ugly article from fibreglass, a material which can be styled to any shape. As the saying goes, ‘If it looks right, it will fly’.
And most importantly, when all the components are assembled into a finished aircraft, it must be capable of doing its job with a substantial margin of redundancy under the most rigorous conditions.
I’m not prepared to compromise on this and this also adds to the time taken up in research and development.
The sum of all of this is that the project has taken far longer than anyone, particularly me, anticipated. From the time I started to build the jig for the expanded fuselage, I have invested over 6000 hours and from the time I laid down the original rag and tube Sparrow Single Seater in 1985, I have spent over 30,000 hours in the workshop. No complaints, by the way: the second most satisfying times of my life are spent messing around with aeroplanes.
Having said that, I must say that the creative process is a lonely one. Whilst the process of finishing a Sparrowhawk from a kit can be handled by just about anyone in a relatively short time, the creation of the parts can only be done by me, using the computer aided drawing system I was born with: 10 fingers, a brain, a ruler, a pencil and two eyes (lately wearing glasses).
I must acknowledge the priceless contribution of two blokes who have been true believers and supporters, Kev Watson and John Mountford. Kev owns the first sparrow XC to fly and has taken care of the engine installation, wiring, plumbing and trim system of the first Sparrowhawk. John, a retired Ansett Flight Engineer took care of the wing panels, aileron and flap circuits and sheet metal work where needed.
BACK TO THE FIRST FLIGHT.
I was somewhat surprised at the short takeoff roll. The Jabiru 3300 was running sweetly and as the wheels came off, I eased the nose up and stabilised the climb at 60kts. A glance at the VSI showed a healthy climb rate at 1000fpm and the Sparrowhawk felt solid and stable with the Sweetapple prop giving 2900rpm at full throttle.
I climbed to 800ft before turning crosswind. The rudder showed plenty of authority and it was easy to keep the ball in the centre. Up to 1000ft and onto downwind, power reduced to 2700rpm and I watched the ASI build to 100kts. As the speed built, the Sparrowhawk showed a tendency to fly left wing low, easily held with a little right aileron. I increased the revs to 2850rpm and the speed built to a very gratifying 115kts, even in this out of rig condition. A small rigging adjustment later cured the low wing.
I flew around for a while, examining behaviour in a rate one right and left hand turns in the process cruise climbed to 2000ft and tried a stall. With the stick full back and the engine at idle, the nose nodded up and down a few degrees with the VSI showing a descent of 200fpm and the ASI pegged at under 35kts. An occasional gentle right or left wing drop was easily picked up with a touch of the rudder.
Bored, I lowered the nose and headed back for a landing, looking out to locate the strip. When I looked at the ASI again, I was surprised to see that the shallow descent at 2800rpm had built the speed to 145kts. A very slippery aeroplane!
At this stage I was able to relax a little and move my attention from flight performance and behaviour to an assessment of the ergonomics within the cabin. At 46” wide the Sparrowhawk is 7” wider than a Cessna 172 in the cabin. There is plenty of head, leg and hip room and the seats are thickly padded. Your right forearm rests on the padded rest between the seats, operating the centre stick using wrist movement only. There is an arm rest in the doors. There is an arm rest in the doors. With the low nose and scalloped instrument hood and deep screen along with bubbled windows in the doors, all round view is excellent, particularly over the nose.
The ailerons are a little heavier than I would like (soon to be remedied). The flaps are electric using a little electric motor with lead screw which previously lived in a Mercedes Benz seat (classy!) and subsequent flights have shown them to work very well.
The Sparrowhawk trims into stable level flight and one can relax in armchair comfort and enjoy the rapidly passing scenery.
I had decided not to use the flaps on the first light, preferring to examine their effect at altitude later and had to abort the first approach because I couldn’t slow it down enough.
The second approach was a long one with a trickle of power and Kev’s patented spring trim system holding the nose up for a speed of 45kts. The wheels hissed, we floated a little and she settled down nicely. Use of flap on subsequent landings has made them much easier and even shorter.
As always, there are a few changes and adjustments to make. I’m not happy with the tail wheel spring which is a steel rod and no matter how I mount it, it loosens up and rocks from side to side, making the aircraft squirrely on the ground. This can easily be replaced with a flat leaf spring. The low left wing was easy to rig out and I also increased the up elevator travel slightly, giving a more positive but still docile stall.
There were a number of my Gold Coast Sports Flying Club mates observing these goings-on and they gathered around as I shut down, commenting on how fast the Sparrowhawk looks from the ground.
The figures quoted here are from the ASI and I have no idea yet what the position error is, if any. This will be checked soon both by GPS and a trailing static port.
John Mountford has made up a mount for a video camera in the cabin shooting the instrument panel and we also shot the flight from the ground with the cameras synchronised, enabling us to analyse the performance at our leisure. Preliminary, figures suggest a cruise of 100kts at 2650rpm and a fuel burn of around 14 litres per hour. This gives an endurance of 6 to 6.5 hours with reserve. With the rig sorted and some fairings to be fitted, 2850rpm should yield a cruise slightly better than 120kts and a burn of 18 to 19 litres per hour, giving a still air range of 600 nautical miles. This makes it a useful cross country and touring conveyance and with the docile slow speed performance, you have an excellent short rough field aeroplane.
As mentioned, it was a hot, gusty day and the Sparrowhawk responded to even the slightest bump. This has led to considerations of a shorter ‘speed’ wing. The wing is made from 24” panels on a 5” tubular alloy spar (which is rated at 8G at 544kg) and this makes it easy to use a 5 instead of 6 of these panels in a shorter wing. This is under way and I will look forward to reporting the results.
The process of generating the tooling for this airframe also yielded a set of production tooling and we are currently building components for stock.
Production airframes with engines in the 65kg range will come in at around 340kg. Engines in the 80 to 150hp range can be used. We are currently working up a set of plain or amphibious floats and an underbelly cargo pod. Basic Airframe kit price is under $40,000.
Whilst it falls well within the 51% rule, the kit is very easy to assemble. The fuselage comes joined, with a carbon steel birdcage bonded in the cabin area. Laminate is foam sandwich, with the area from the firewall to the trailing edge incorporating a carbon fibre/Kevlar twill weave cloth inner layer. This makes the cabin area about the equal of a F1 driver capsule.
The wings feature a 5” x 1.6mm 6106 tubular alloy spar over which the composite skin/rib modules are slid and fixed with acrylic adhesive and hose clamps. Each wing can be assembled in a couple of hours on a flat table and left overnight to cure. Ailerons and flaps come joined, requiring only preparation and painting.
The landing gear leaf is a continuous bow made up of around 10,000 runs of pre-wet continuous filament fibreglass rovings in a cavity mould and is very strong.
The fuel tank comes complete with baffles and feeder sump and simply bolts into the fuselage along with the seat unit fitted over the top.
Tail surfaces come joined and only require the fitting of the carbon fibre hinge brackets and preparation and painting.
Apart from the assembly of the wings, all structural fibreglass work is done at the factory, leaving some minor bonding of brackets etc by the builder. In fact most of the estimated 300 to 350 hour assembly time by the builder is made up of the fitting of control runs, upholstery, instruments, wiring, plumbing and engine installation followed by preparation and painting.
As mentioned, we are currently building smaller components to stock and we have three orders in hand. Planned production for 2007 is 14 kits.
We are confident that the Conroy Sparrowhawk will gain a significant share of the growing LSA market and during this first year of serious production, we will be expanding our production tooling to be capable of making up to 50 units per year. This will cost money and our Company structure allows us to sell equity in order to fund the expansion. We already have interest from South Africa, Dubai and the USA so the future looks bright indeed.