SA Flyer magazine (March 2006 issue)
Corrected and updated 2008
Flight test and technical report of Aerokopter’s AK1-3 SANKA helicopter.
After my initial visit to Aerokopter in June 2005 to test fly their pre-production helicopter, I revisited the plant again with Mr. George Snyman of Nelspriut in late November to view and fly one of the first helicopters off the production-line. George, a seasoned helicopter pilot with many flying hours is also a qualified helicopter technician and was looking for a replacement helicopter after selling his beautifully finished Rotorway 162F. George has also previously owned a four place Hiller, R44 and Hughes 300 C.
I found the Ukraine a country of contrasts. Observing the farmland over France and Germany, the patchwork of small farms looks like a quilt in stark contrast to the enormous farm fields of the Ukraine. Where the Europeans would measure in hectares the Ukrainians would measure in square kilometers. Arriving at Kiev, the capital city’s Borispil airport, which is about the size of Durban airport, I caught a connecting flight to the city of Kharkov in east Ukraine. (Due to a last minute visa problem, George only arrived two days after me.) This city of some 2 million inhabitants has a very small airport. The small passenger terminal building, which I had completely missed on my first trip, is only used for departure. Arriving passengers walk off the plane, collect their luggage from a hand pushed trolley, walk through a steel door in the “airport” perimeter wall and into the parking lot, where I met my contact and interpreter Mr. Alex Miroshnichenko. The roads in and around Kharkov are not in a very good state but the many public gardens in the city center are very nice and meticulously kept. It is true, the women in Ukraine are mostly very beautiful, and no, I had not been away from home long. The people are very polite and friendly and there are many new opportunities opening up in that country for bold entrepreneurs. The worst part of Ukraine for me was my inability to speak or understand Ukrainian or Russian and to top it all, their Cyrillic alphabet is different to ours. Later, when returning via Germany I already felt I could half understand German just because I could read it, even though I don’t understand German either.
The Aerokopter factory is located in Poltava some 130 km from Kharkov. This town of some 300,000 inhabitants looked rather depressing and run down, made worse by grey skies and rain when I arrived. The Aerokopter factory is situated in a narrow suburban street and these streets have not seen road maintenance by the impoverished local council since they were built a long time ago. I. E. large potholes every where. There were no road name signs or traffic signs visible, so an English speaking tourist with a road map would have no chance of finding their way.
The factory itself consists of several separate old looking warehouse type buildings in different stages of renovation, around a large open yard. My thoughts on arrival at Aerokopter the first time were, “Why have we stopped here? They couldn’t be building any helicopters here!” Well they were!
Stepping inside the first building through a solid steel door, and up narrow concrete stairs we were led to the managing director’s office and introduced to Igor Polituchiy, himself a helicopter pilot and major shareholder of Aerokopter.
With introductions and pleasantries done via Alex translating, Alex and I then started on my tour of the factory.
Inside, the various areas containing the different manufacturing departments were in stark contrast to the dreary outside. With building renovations still underway, most rooms had been completed and were clean, bright, and very neat inside. This same contrast we experienced at the flats that George and I stayed in during our visit. Old and decrepit on the outside, but superb and modern inside. A strange type of property sectional title exists, where the state still owned the building structure and common areas, but the individual flats were owned privately.
The design office is equipped with numerous PC’s and the staff were busy manipulating drawings on CAD type software. A small demonstration by one operator showed a complete helicopter on the screen, then removing pieces on the PC and zooming in, till we were down to minute detailing on one selected part deep inside the helicopter. Quite amazing to see! But that was only the beginning. Each of the components that would require machining in their manufacture is linked to further software that calculates and plots the tool paths of some of the various machining centers in the machine shop. These computer numeric controlled (CNC) machines then physically cut the 2 or 3D shapes out of the various solid materials. This Computer Aided Machining (CAM) is a modern high tech manufacturing strategy that has allowed relatively quick development of the helicopter allowing for rapid implementation of design changes and quick manufacturing of new parts.
This type of manufacturing infrastructure is not usually cheap to set up, but allows a consistently high quality of machining to within very small tolerances.
Aerokopter have utilized this strategy to the maximum by machining hundreds of different components from solid billet raw material. The quality of fit and finish of all these components is outstanding! There are no castings used in the production of the Ak1-3 Sanka, even the large main rotor gearbox casings are machined from solid bars of aluminium alloy.
Clearly, Aerokopter had focused their limited capital resources in the right areas of the business to develop an excellent quality product and chose good manufacturing capabilities rather than glitzy offices to start with.
The brightly lit machine shop itself occupied the largest space of the entire plant which currently occupies over 1200 square meters and growing. The selection of different types of machining centers although relatively old is enough to make a toolmaker’s heart fill with joy and some two thirds of the helicopters components are manufactured in house.
The small welding department is dominated by a robust looking welding jig in which an air frame was in the process of being welded. The quality of the welding is superb. The exhaust system, lower skid leg attachments as well as the Titanium-tube seat frames are welded here. The small air frame is made from chrome alloy tubing and is triangulated in design for maximum rigidity. The Skid legs are made of 51mm Titanium tubing and are attached to the air frame by semi circular clamps with a rubber bush insulators. The lower skid foot then holds the 60 mm diameter Duralumin skids to the Titanium legs.
The blade making department had several long blade moulds in various stages of rotor blade production. The composite main rotor blades are constructed from three main elements. First a rectangular shaped spar is created from composites. This spar is then cured in its electrically heated mould. This high tensile spar is then placed into the blade mould where shaped lead weights are placed along the outboard front leading edge together with Rohacell foam trailing edge inserts. This whole assembly is then skinned in composite material and cured. Stainless steel bushes at attachment points and the leading edge wear strip is applied once the blades have been cleaned and painted. The tail rotor blades are also made of composite material and Rohacell foam. Each main rotor blade has a non linear twist of 9.5º and a variable profile and thickness along its length. The quality of finish was excellent. These blades have no life limit and are only replaced on condition.
The Instrument pedestal, tailboom, horizontal and vertical stabilizers was assembled in the sheet metal room. The tailboom assembly including the stabilizers is made of formed and riveted sheet metal sections and during construction a large assembly jig is used for proper alignment of all parts. Inside the tailboom are 3 x CNC machined internal ribs, equally spaced to carry the tail rotor shaft support bearings. Even the internal ribs for the stabilizers have been CNC machined from solid aluminium and all rivets are solid, no pop rivets. Only close up photos will do justice and show the overall quality of this tail section.
The cabin structure including door frames are made from a composite material. The composite fuel tank is made from sections bonded together. It incorporates brass fittings for the fuel filler cap, fuel drain valves on each side and the fuel level sensor attachment point. The cabin floor is unusual and consists of two components, a 16mm plywood and foam floor and supported by a triangulated aluminium sub-frame below, that attaches to the steel airframe. The cabin floor is made by machining out different sized squares from the plywood so as to leave a light wooden grid to which other parts will be bolted to. All the machined out wooden areas are then filled with foam inserts to replace the wood removed. Then a skin of composite cloth is applied to both sides. The result is a very light and riged floor with the wooden grid matching the aluminium frame below where they are joined.
The gearboxes and swash plate are assembled in a clean room that also stores the components for their assembly. The heavy duty drive line components are out sourced from specialist aeronautical manufacturing companies. These include the steel alloy rotor head components, Main rotor blade holders, Main and tail rotor transmission gear sets, V-belt reduction drive shafts, sprag clutch and main and tail rotor shafts. Each of these components had serial numbered tags attached to them with component documentation, which I presume was a necessity for obtaining type certification in the Ukraine. The heavy duty hardened and precision ground steel spiral beveled gear sets are very beefy indeed and would do proud inside a large truck differential. From my intuitive mechanical perception, it appeared that all the propulsion driveline components looked over-engineered and should last a very long time. Both main and tail rotor transmissions have a large oil level sight glass and magnetic screw plugs (not chip detectors). The main transmission also has a temperature sensor.
Another interesting aspect of the Main rotor transmission and pulley reduction drive system, is that it does double duty as part of the airframe structure, thus reducing the actual airframe size and weight. This concept is used very successfully on motorcycles and in Formulae-1 where the engine and gearbox forms part of the frame.
While the largest and main assembly hangar was still being renovated, a smaller “show room” stored the complete and painted subassemblies and doubled as an assembly area. Here, there was an unpainted assembled sample of the flight control system that I could inspect in detail. The amount of detailed machining of the control system is amazing. Even the most mundane little re-enforcing brackets used in this assembly are CNC machined from solid stock, including all bolts made of Titanium. Overall the controls look robust and every part that moves or rotates is fitted with sealed bearings and locked with either castle nuts and split pins or safety wired where needed. There are adjustable frictions for both cyclic and collective controls. The Collective lever has an interesting mechanical mechanism below the floor that keeps the lever in the down position via a spring loaded override arm, but when you lift it a few centimeters up, it becomes light and with a little friction applied will remain in what ever position you leave it in, but still easily moved if need be, thus making longer flights less tiresome on your left arm.
It had stopped raining by now and Alex called me out to the yard where the demonstration helicopter with Victor Tomilin the pilot and company director was waiting for me. The demonstration helicopter is the second prototype and their pre-production craft . This helicopter was being used for type certification and has been flying for two years. This demo craft had additional measuring equipment installed on board to measure control inputs and loading. It also had its vertical and horizontal stabilizers removed and in its mounting point a control measuring devise was fitted. The production helicopter was will little changed mechanically from this demonstrator, testament to good design know how by getting it right first time. The result is a helicopter with a empty weight of 410 kg.
Approaching the helicopter from thirty meters away there was no sound, yet the rotors were turning and I thought the engine had been switched off, but as I approached, I realized it was idling very quietly. With Victor as instructor and pilot in command in the left seat, I climbed in on the right. Getting into most small helicopters is usually a bit awkward and the AK1-3 Sanka was no different to a Schweitzer / Hughes 269C. There is a beautifully machined Duralumin foot peg on each front skid leg to ease climbing in. The trick is to first place your butt on the seat, then swivel your legs in with one leg swinging over the cyclic control. Whew!
Relative size of cabin