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About the AK-1 Mk3 |
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was not their worst setback. Just one month after their chief designer Zapishniy Alexander Nikolayevich, had joined the group, he was killed in a motor hang glider accident. The group found the strength to carry on under the leadership of Slava Sherbak, a talented and very skilful designer and so in Alexander’s memory the new helicopter would bear his nick-name “Sanka”. Zapishniy’s idea of a two seat helicopter of truss structure was taken up and the design team has not looked back since. The core design team consisted of passionate individuals of different technical disciplines, including former military test pilots. Much of the experimental research was done in close co-operation with post graduates and professors of the Kharkov National Aeronautic University. Additionally, a specialist aeronautical company was engaged to design the power transmission and gearboxes. On my first visit in June 2005, the Aerokopter design office was equipped with modern computing hardware and software including Auto CAD, NASTRAN, Mechanical Desktop, Fluent, X-foil and other integrated packages. While touring the factory I witnessed some of this integration software at work. With the whole helicopter having been designed using Computer Aided Design (CAD), one operator had demonstrated on his PC the ability to disassemble the helicopter part for part, zooming in on individual components showing every detail. Further software integration involved the calculating of the machine-tool paths which was then passed down to some Computer Numerically Controlled (CNC) machines in the machine shop, where many components are manufactured. These CNC machines comprised mostly older generation, but solid Lathes and Milling machines that cut out the component from a solid piece of raw material. There were still several skilled artisans working traditional (Non CNC) machines turning out components too. Although costly to set up initially , this CAD and Computer Aided Machining (CAM) manufacturing strategy would pay dividends down the line by shortening the design-to-production time considerably, whilst able to maintain very small tolerances and yield a high quality of finish during production runs. The machining of components from solid metal billet is more expensive than casting, but the due to better raw-material grain-structure control, is generally stronger than castings for a given size. Aerokopter use in house manufactured Titanium bolts instead of the more familiar "AN" bolts in most applications, for its strength, light weight and anti-corrosion. On 12th October 2001 the first experimental prototype helicopter, the AK 1-5 Sanka flew. This was used for proof of design concept, assessing flight dynamics and ground and factory tests so that constructional elements could be improved and manufacturing processes and tooling could be established for production. This experimental helicopter had a five blade rotor head and tested with different Subaru engines including the 3.0 L flat six, the 2.0 L turbo and 2.5 L normally aspirated power plants. The second helicopter built, the pre-production prototype AK1-3 Sanka, flew in July 2003. This was the helicopter I test flew during my visit. The factory currently covers an area of over 1200 m² with additional existing old hangars still being renovated which will then become the main assembly area. 65% of the components were manufactured in house in 2005 and this percentage is increasing to improve quality and shorten lead-time by eliminating some unreliable subcontractors. One has to slow down and be very patient in the Ukraine, as time is not yet seen as a limited resource and due dates are usually not kept to. Pilot production started in 2005/6 with five helicopters being built. Production capacity is slowly increasing and at last count was at twelve machines a year which will be increased over time as demand dictates. The factory quote production lead time, I.E. time to manufacture the components and assemble varies of approx. 12 to 14 months depending on work load. There are relatively few mechanical design changes to the production-series helicopters, testament to a good initial design and the design teams expertise in getting a complex machine right first time. Aesthetically the interior of the cabin has also been made much smarter than the utilitarian layout used in the SN 0001 prototype model. All these changes have necessitated an upward revision of the factory selling price of the basic helicopter, but compared to what is available in the market currently, I believe that the 1-3 Sanka still represents good value for the quality and performance offered and without a calendar time limitation before overhaul. The 1-3 Sanka received its APU - 27 (FAR - 27) Ukrainian Type-Certificate on 30th June 2006. In Ukraine type certification can be obtained for an aircraft including its installed engine, unlike in most western countries where the engine has to be independently certified. The AK1-3 Sanka is powered by a non-certified, normally aspirated Japanese manufactured Subaru EJ-2.5 L motor car engine, therefore the factory built and assembled 1-3 Sanka helicopter will be imported into South Africa as Non Type Certified Aircraft (NTCA) the same as kit-built or ex-military aircraft. These will be registered with the South African Civil Aviation Authority (SA CAA) in the NTCA category with the prefix ZU in the aircraft registration. The advantage of non-type certified or ZU registered aircraft is that you are allowed to maintain and service the aircraft yourself if you so wish, and provided that you are technically minded and competent, thereby substantially reducing your operating costs. In addition engine service parts and engine overhaul costs are lower than for traditional aircraft engines, as parts can be obtained direct from the nearest Subaru dealer who can also perform or arrange for engine overhauls. The down side is that you may only use it commercially under the more restricted operation as defined in part 96 of the CAA regulations, which are currently under review. For example, you can use it for “flipping” provided that you have been issued with a class II – type N1 domestic air service license, which restricts you to take off and land from the same spot. You are also compelled to disclose to fare paying passengers that the aircraft is non-type certified and that they fly at their own risk. The helicopter may also be used for training purposes, provided the operator is the holder of the appropriate aviation training organization approval, issued in terms of part 141 of CAA regulations. The 1-3 Sanka has been designed to be easily transported by road trailer if required, even with a small car. The three main rotor blades can be removed or installed in 10 minutes with two persons. |
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A little background: With Ukraine now free of the shackles from its former master, the Soviet Union since 1991, and with new economic freedom for its citizens, the Ukrainians have wasted no time in developing new businesses using what little resources available to them. A recent request from the Ukraine State Border Committee seeking a suitable light helicopter for border patrol and willing to support the local aviation industry by sourcing such craft from within, has sparked an increase in their local aviation industry. The options of using imported helicopters from Poland or Russia had proved too costly for this young democracy. One of these new start-up companies is Aerokopter. Founded 14th December 1999 by I.V. Polituchy, A.N.Zapishny and A.I. Polituchy, the Aerokopter design team based in Poltava had been chosen as winners of a competition initiated by another existing company called Aviaimpex of Kiev, to co-develop and later manufacture a light helicopter. Unfortunately the two design teams split up within months, with Aviaimpex forming its own design team in Kiev. So from 3rd May 2000 Aerokopter had to go it alone in Plotava, but this |
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During transporting, the main rotor blades must be stored in a purpose made holder for protection. With the 1-3 Sanka running on unleaded petrol, which is available almost everywhere and also substantially cheaper than Avgas, this makes for a very convenient and mobile flying platform….Perfect for aerial photo operations, or just taking it away on holiday with you. ……….An enviable ability and freedom to go anywhere unmatched by the best 4 X 4's. There nothing quite like, flying and arriving on that magic carpet............ a helicopter! |
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THE HELICOPTER: After some market research Aerokopter concluded that a need for a light two-seat helicopter in the 650 – 700 kg gross weight category existed. The end result of the design-team’s creation is a helicopter capable of delivering a maximum vertical thrust of 800kg from its 115 kw (156 hp) motor. There are "flight performance graphs" from the Pilots Flight Manual available on the home page for those who wish to analyze the helicopters performance in more detail. Airframe: The small truss-type airframe is made of triangulated Chrome Alloy tubing with two separate upside-down “V” side frames used to attach the Main Rotor Gearbox (MRG) to the air frame. Also detachable are two engine mounting sub-frames that carry the engine weight via rubber insulated engine mounts below the engine. On each lower corner of the airframe is welded a large circular clamp through which the 51 mm diameter Titanium-tube skid legs pass through. At the front of the airframe are four attachment points that hold the cabin-structure in place. All structural bolts used throughout the Sanka are metric sizes and made from Titanium. The cabin floor is fastened on top of a triangulated Duralumin sub-frame and this sub-frame is attached to the Chrome Alloy airframe. Detachable side frames attach to main rotor gearbox. |
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These skid-legs are single-piece U-bent tubes and are secured via rubber bushes inside these circular clamps. The lower end of each Titanium skid tube has a steel foot attachment to which is fixed the Duralumin skids. This “under carriage” looks very robust yet is extremely light-weight. Each skid has a Duralumim Dolly-wheel attachment-point and on each side of the front legs are beautifully machined Duralumin foot pegs to assist entry into the cabin. |
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The MRG and integral primary reduction drive unit together form an upside-down “L” with a cross brace linking the two ends to form a triangle. This triangle then forms part of the airframe structure and is the attachment point for the front of the tail boom and top engine mount. There are two Duralumin diagonal struts attached on each side, at the rear of the airframe and these attach to the underside of the tail boom to support it approx two thirds down its length. The use of the MRG drive system as part of the airframe is unusual in a helicopter and is the same principal used in formulae-one cars and super-bikes where the engine-gearbox forms part of the chassis. By using this integrated truss-frame design has allowed the use minimal amount of Chrome-alloy steel tubing without sacrificing rigidity, but saving weight. |
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Note that the skid legs (2) are made of one single Titanium tube 51 mm diameter. |
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Tail boom:
The tail boom is made up of four rolled aluminum sheet sections, forming tubes and riveted together using solid rivets. At the three joins connecting these four tube sections, are large machined ribs that hold the three tail rotor drive shaft support bearings. There are four additional smaller machined ribs positioned midway the length of the four tube section for maximum rigidity. Each of the tail rotor drive shaft bearings is held in a rubber pad, which in turn rests inside an aluminum housing bolted to the large ribs, thus allowing some "float". The drive shaft is a single length 22 mm chrome alloy steel tube with collet bushings clamped onto the shaft in line with the support bearings. At each end of the drive shaft a electroplated steel coupler is fitted using two conical bushes and a Titanium bolt. Next to the front coupler is a light steel gear wheel with 24 flat teeth. This "gear wheel" is the rotor RPM magnetic sensor trigger, with each gear tooth passing over the magnetic sensor generating an electrical pulse to power the Rotor RPM instrument. In the event of complete electrical and power failure, the Rotor rpm instrument will still work during autorotation. The tail boom has re-enforcing gusseting added at strategic locations, such as at the tail boom mounting points, at the vertical and horizontal stabilizer attachment points and where the anti-torque control cable guide pulleys and rear control quadrant are attached. The horizontal and vertical tail fins are fabricated from riveted aluminum sheet onto CNC machined ribs and end caps. All the tail boom bracketry is CNC machined and any material not adding strength, is machined away to save weight. Where ever a Titanium mounting bolt needs to pass through the Aluminum structure, a stainless steel or Titanium collar is first inserted As can be seen from photos the attention to detail and workmanship is excellent. |
