Flying the GK1:
Flown by Russell Phillips
My first flight in this machine was with the normal trepidation and nervousness one has at flying something new. In this case, it was really new – this is the first GK1 in the world! This machine was designed for speed.
The nose is very long but fortunately, forward visibility is not too bad as the nose is also very narrow. The first impression, as you open the throttle to taxi, is that you are flying a turbine due to the high-frequency whine and smoothness of the engine. The engine drives the prop through a toothed belt reduction drive which results in a lot less of the low rpm clatter one gets with other gear systems. Take off is an exhilarating affair as the power to weight ratio is spectacular. The aircraft has reasonable taildragger manners with a powerful rudder. “Liftoff” happens at about 70Mph and initial climb rate is in excess of 1200ft/min.
The most striking recollection I have of the first flight is the control harmony that has been achieved in this design. I have read of the classic ratios between elevator, aileron and rudder forces which designers aspire to. Some aircraft which apparently have come close to these ideal ratios are the Chipmunk and Pitts S2A. I would liken the delightful control harmony of the GK1 to the Pitts S2A. Roll rate is yet to be accurately measured but is in the order of 180deg/s making multiple aileron rolls and hesitation rolls a pleasure. In straight and level flight the aircraft does what it was really designed for …..speed! After levelling off a quick glance at the airspeed indicator yields a pretty impressive speed but patience is required as this machine seems to take about 2 minutes to really get going.
The radiator is built into the rear fuselage and has an adjustable cowl flap. Once one is established in level flight the coolant temp is monitored and the cowl flap progressively closed. The first time I tried this I could not believe the reading I was getting on the airspeed indicator. The needle was almost on the stop!! Next flight was with a GPS which verified what the gauge was reading – approximately 160kts! This is an impressive speed in a machine that is burning about 17lites per hour! Stall speed is a low 45Mph IAS with very little wing drop. This is probably due mainly to the use of a well-proven wing section (RAF 48) known to have docile stalling manners. The circuit and landing can be interesting if one leaves the slowing down process till too late. With no flaps, the only way to lose height is by sideslipping. This is also a useful way to see the runway over that long nose. A well-planned approach flown at about 55Mph IAS with a sideslip works well and the aircraft touches down gently on its spring steel undercarriage. With a few practice landings, a 400m of runway is quite feasible. Directional control during the final stages of the landing roll requires a bit of footwork but nothing that a competent taildragger flyer would have a problem with.
Flown by Neville Ferreira
Wow wow wow..... That was my first impression.
The take-off went without a glitch after keeping her on the ground until she wanted to get airborne. Climbing out at around 90Mph she felt solid and responsive. Once at around 2000 feet above the ground, 6500 amsl she settled in the cruise at around 185Mph with the engine at 5300rpm.
At full throttle, she reminds me of a racecar as the 4 cylinders reached 6000rpm. This is something to get used to after flying 6 cylinder Lycoming engines with max rpm below 2900rpm for the past 8 years.
By comparison to the modern high price tag aerobatic aircraft, this offers a kick in the pants experience that you just do not associate with an aircraft at this price tag. Where have you seen a 100Hp engine delivering 200-220Mph speeds with less than 20Lph fuel burn? Although this aircraft is not marketed as an aerobatic aircraft she is 100% capable to perform loops, rolls and any basic manoeuvres. But the fun lies in the flight itself.
This little aircraft with a 6meter wingspan requires only the corner of your hangar but once you have strapped her on you will be forgiven as she flies as well as any $440 000 aircraft.
Cruising at 185Mph I took my hands and feet off the controls and she remained stable without the tendency to pitch or bank even though she has a straight wing with zero dihedral.
On landing with an approach speed of around 55Mph she touched down and used less than 450 Meters of the runway.
This is not an alternative aerobatic aircraft, It is a RENO RACER on steroids with a price tag around the $100 000-$120 000 depending on options ready to fly.
The engine sounds just like an Italian sports car if you stand on the ground.
The wings have two substantial single piece laminated wood spars. The wing has a foam core with a fibreglass skin. The one-piece wing fits into a cutout in the underside of the fuselage. Ailerons employ aerodynamic balance tabs which help reduce stick forces. The canopy is a portion of a glider canopy and blends very neatly into the fuselage lines. The wheel spats are a very tight fit around the wheels and are blended carefully into the spring steel undercarriage legs.
Every attempt has been made to reduce drag with even the tailwheel closely faired. The engine cowl has no air inlets thereby reducing cooling drag to the absolute minimum. The radiator is mounted in the rear fuselage and draws air in through an under-belly scoop similar to a Mustang. The workmanship on the aircraft is superb with great attention to detail. A big emphasis has been placed on weight reduction and hence the cockpit is spartan and functional.
The end result is that the GK-1 is a machine that certainly achieved and surpassed it’s design goals. Anyone who has considered designing and building an aircraft single-handedly from scratch will realise what a notable achievement a project like this represents.
The cockpit will accommodate any pilot with an average build and up to 6 feet tall with max weight of 125Kg or 275Lbs.
Stall speed: 42Mph
Cruise speed: 185Mph @ 5000Rpm (Max Rpm 6500)
Approach speed: 50-55 Mph
Fuel burn: 4.5GPH / 17Lph @ 185Mph