(By Frans Grotepass)
The Vansin is a unique aircraft. The product of the prodigiously talented and skilled Carel van Aswegen – this wonderful example of the homebuilders’ art is being cherished and continuously refined by the inimitable Prof Frans Grotepass, a retired Voluntary Red Cross Air Mercy Pilot and still an active maxillo-facial surgeon in Durbanville Cape Town.
The Remarkable Carel van Aswegen
Carel van Aswegen was born in the Orange Free State in 1923, so his youth was during the depression years and the Second World War.
The early years of his life were hard. As a young man he had to leave the comfort of academia and help his father in the building trade. Being a practical man, his father taught young Carel the secrets of cabinet making and instilled in him a superior sense of working with different materials.
His father must have recognised young Carel’s natural ability of working with his hands and the stimulation at a young age created the man I was to later meet in Plettenberg Bay. Our mutual interest in aircraft and the amateur building of these wonderful machines was the secret ingredient to our mutual friendship for the years to follow.
Carel arrived in Plettenberg Bay in 1957 with his wife Joey de Beer, who he had married in Bloemfontein on his birthday on 26 June 1947. I can identify with that decision because I was married on my 25th birthday and have now been married to my very longsuffering and forbearing wife Mari for 54 years.
When he arrived in Plett, Carel worked for a builder, Kou Reddering. This coincided with the discovery of the Formosa Bay area as an area of magnificent natural beauty and a boom period followed. As a builder Carel noticed the poor quality of the available bricks. His natural instinct for materials kicked in and it wasn’t long before Carel made his first batch of bricks. He sourced the correct clay, mixed it using his ingenuity and created a brick production service. The rest is history as Plett was booming and Carel supplied the bricks.
With his business flourishing he could now spend his spare time on dreaming and building aeroplanes.
Mail order catalogues for aircraft parts had started in 1965 in the USA but in South Africa nothing was freely available. Being a practical man, he was soon acquiring various aircraft wrecks. Amongst the various parts were the remains of a Cessna 170B, Piper Apache PA23. Wings, the engines of a Twin Comanche and various other parts that were a constant source of hardware for his building. Carel was rebuilding a Tri-Pacer, Piper Cubs and a Cessna 140, ZS-YLU. All these aircraft showed superb craftsmanship.
Designing and building new brickmaking machines also kept him busy and his wonderful brain began thinking of a new aircraft. Applying his renaissance brain and mixing it with his dexterity and his natural evaluation of material strengths gave him an inbuilt ‘wetware’ version of an AutoCad Solidworks combined stress analyses program.
His ability to think logically was not clouded by intellectual facts
His strong ability to think logically was not clouded by unnecessary intellectual facts. His first self-designed aircraft was the Bergwind ZS-UIS which, on the 17th April 1977, was officially presented to the public. It was a single seat low wing aircraft with modern lines and a 55hp Lycoming engine driving a three bladed wooden propeller. The then DCA (which were always helpful) admired the wooden prop but queried the strength. Carel insisted it was strong enough as he had done the lamination and the gluing. DCA insisted it be tested and supplied him with the load that the blade was subjected to under flight conditions. Carel quickly made another stinkwood prop with a duplicating machine he designed, a structure was built the propeller suspended and the required load was applied. Nothing happened so he decided to load the prop to see when it would break. It never broke, but the supporting structure collapsed. The test propeller adorned his hangar and was the start of many discussions.
The prop duplicating machine was donated to his sister’s son who showed an interest in woodworking and propellers. His name is Pieter de Necker and he has gone on to become South Africa’s foremost wooden prop supplier.
The Birth of the Vansin
Meanwhile Carel’s brain was now working overtime, sketching aircraft shapes and lines on his hangar walls. He liked low wings and wanted something more practical than the single seater Bergwind.
He reasoned he could combine the aerofoil of the C170 with the PA23 spar
The main spar of the PA23 Apache was a nice strong structure – and the Cessna C170 has a wonderful aerofoil profile. So he reasoned that he could combine the aerofoil of the Cessna 170 with the PA23 spar. But it had to be a tapered wing, and aesthetics were important. So the ribs were made for the aerofoil. The bell cranks, flap mechanism hinges and other hardware were all donated from the 170B. The wingtip was completed with the tip tanks from the Twin Comanche. The main fuel tanks were also grafted from the 170B.
The whole aircraft was completed with countersunk rivets, minimising drag. The fuselage was designed around two reclining chairs and the structures were laid out. The C170Bs fuselage structure turned upside down was found to be perfectly suited to the overall profile of the airframe and tailcone. The tail feathers were all new in profile. The Cessna empennage was the correct size the lines had to fit with what Carel had drawn on the wall and on the floor. The remainder of the design was in his head.
The engine would be the Lycoming IO-320 turbo normalized engine from the Twin Comanche, so the firewall forward was grafted from the PA30 Twinco.
The fuselage was finished and balanced and then placed on the judged centre of lift of the wing. The wing and fuselage were mated and voila! The CoG was sorted.
It takes a special brain to be so practical and clever.
For undercarriage, the spring steel gear legs of the C170 could not be improved upon and all the necessary fairings were made to improve the aerodynamics.
Now for the windows. Easy. Carel said he would blow them himself. He built a big box and the correct frame and clamped the acrylic sheet. This big box had a big inlet and outlet for air. He brought his bulldozer from the brickyard and connected the exhaust to the inlet. The outlet was left open, then the bulldozer was started and the acrylic sheet was warmed up till the softness was just right. The outlet was then closed. The exhaust pressure blew the acrylic into the correct shape and at the right moment the engine was stopped and everything cooled down. It takes a special brain to be so practical and clever.
The aircraft needed a name. Van had built it, so it became the ‘Vansin.’
The Vansin led Carel to build a helicopter – based on the then available BabyBell helicopter. It became the Carelsin 1, ZS-VJX, powered by the second engine from the Twin Comanche. Once it was finished, he couldn’t fly it as there was nobody to teach him. So he tethered the helicopter to a big frame made from aluminium irrigation pipes, and started hovering. He slowly lengthened the tether and training progressed until Carel was flying all over the farm.
He thought he should get it legitimate. The big day arrived when Captain Jerry Broberg of the then DCA came to test fly the new helicopter. The flight was successful and Broberg remarked that the helicopter flew very well, but was extremely sensitive to control inputs. Carel remarked that he did not find it so sensitive and Jerry just frowned, as he was after all representing DCA.
Frans Grotepass and the Vansin
Back to the Vansin. During its build Frans visited Carel often and his two boys, both under 10, were always full of enthusiasm with uncle Carel. They were allowed to play hard and it made a lasting impression on their developing brains, as they learnt that if you put your mind to it, anything is possible.
Frans writes, “I made Carel promise that if ever he wanted to sell the Vansin I must have first option to buy this aircraft. So the day arrived that Carel wanted to part with it. He was however reluctant to sell as he wanted to break up the machine, being scared of litigation. I went to the attorney Rassie Theron in Plett, also a keen aviator and he drew up a contract with which Carel was happy. And so the Vansin moved to Grootfontein Airfield in Cape Town.
Now having the Vansin under my roof meant that I could consider refining an already lovely aircraft. An obvious place to start was the instrument panel which was from the 60’s, with lot of instruments all over the place. I had soon discovered that when flying the Vansin she was easily loaded beyond the aft CoG. I really wanted to improve this problem but had no plans and no real CoG data.
I started looking at the CoG limits on the Cessna aerofoil and marked the limits with a pencil on the wing, followed by a critical weight and balance with all the various loading possibilities. I found that I needed 50 kgs of weight in the nose. Being experimental, I made a custom lead ballast and fixed it to engine. With that weight on the nose, she flew beautifully. So the solution was easy; the engine had to be moved 180mm forward to give a practical CofG range.
A new engine mount was made and while the engine was out, a top overhaul was done on the Lycoming. Moving the engine forward was not just a matter of bolting it to a longer engine mount. It needed new control cables, and sensor leads and much more. It was more work than anticipated – and also the cowling had to be extended.
The Long Nose Vansin
The end result was fantastic. The aeroplane is fast and stable and a great long distance cruiser. Many long flights have been flown including from then Cape to northern Mozambique, Botswana and Namibia. She carries 266 litres of fuel giving a 7 hour endurance at 140 kts at 7000ft.
The empty weight is 80 Kgs lighter than a C172, and the all up weight is the same as the Cessna 172, yet with the same horsepower.
After taking it over I also simplified the fuel system. All the fuel hoses were replaced with Teflon wire-braided fuel lines which have unlimited life expectancy. The gascolater was moved to the right leading edge and now incorporates the Weldon prime backup pump. All the fuel transfer from tip tanks to the main tanks is done with reliable Facet pumps. There is also a pump to transfer the left main tank to the right tank, so after a long cross country flight your remaining fuel can be transferred to the right tank. This arrangement is my choice because I like to sideslip on final approach for speed and height control (still a remnant of my initial training in the J3 Cub).
After a while it was time to replace the patched cowling with a full new cowling and to revisit the instrument panel again. All the gyro instruments, as well as the vacuum pump were removed and replaced with modern MGL EFIS equipment. For redundancy a backup Dynon D3 artificial horizon, which can operate independently of the electrical system was installed.
When I installed the EFIS I put a magnetometer into the wing tip. This gives the advantage of full air-data of which a big benefit is having crosswind information. Having the magnetometer also meant that by adding two auto pilot servos on the CAN bus I could have electronic help flying on long cross-country flights.
The supposedly quick adding of two servos needed me to spend many relaxing hours on my milling machine to make the custom mounting brackets. After setting up the servos and fine tuning, the autopilot flies very well and is a big plus for the operation of this magnificent aircraft.
Losing the heavy vacuum pump and plumbing had a very positive effect on the empty weight.
On the ground
The thought that goes into a custom-made aircraft such as this is immediately evident. The aircraft is beautifully smooth and flush riveted and the flush fuel caps have a simple metal key with two pins. The tuna shaped fuel tip tanks just look right.
The engine cowl cannot be opened without undoing Cleco fasteners and removing a left or right half, so only the oil can easily be checked through its own hatch for the dipstick.
There is only one way into the cabin and that’s through a high-silled gullwing door on the right, but it opens high enough to make access easy. Once seated, the 40 inch wide cockpit is quite tight for two broad shouldered South African males. Although marginally large enough for four seats Frans flies it with two, giving plenty of space for baggage and making the Vansin indeed a great touring plane.
His workmanship is a legacy to a great man and a wonderful builder
An immediately noticeable and unusual feature is the stiffening frame around the cockpit windshield former. This acts as a roll over frame and gives the Vansin a feeling of rigidity and strength.
The seating position is low, with your feet stretched out in front, but it is very comfortable for long trips. The windows, particularly the windscreen, are expansive, giving a great view out. Notable too is that the windscreen does not have a centre brace, which means the compass is mounted on the top of the instrument panel. Hanging from the stiffener is a fine non-magnetic brass screwdriver which Frans uses to fine tune the compass in flight – aligning it with the accurate magnetometer.
The layout of the panel is unusual – particularly in the location of the avionics and switchgear which appear haphazard. The design however was influenced by the many years of instrument flying and the lack of space on the panel. Carel wanted to see over the panel leaving little space. The flying instruments were placed in front of the pilot as well as the radio, the engine instruments were placed on the right with the transponder with warning annunciator lights in front of the pilot. The switches and circuit breakers are located vertically on narrow strips down either side of the instrument panel. The centre of the panel is dominated by the MGL EFIS, and below it are hefty push-pull engine control knobs. Thoughtfully located next to the throttle knob is a flap switch and the fuel pump switch – which can both be operated without taking your hand off the power controls.
On the lower left side of the panel is a large red knob which operates the manual triple K turbocharger suitable for the capacity of the Lycoming and the rpm. The original Rayjay turbo parts supply was a problem. In a rare mistake in finishing quality, the spackle finish on the metal instrument panel is peeling off – which is Frans’ next project.
On the right-hand side of the panel are modern engine health instruments and fuel gauges. Somewhat incongruously – in the middle of the top of the panel and two small switches simply marked ‘Mags’. The prominently located magneto switches were placed there so that the position of switches can be seen during a walk round inspection b and the safety of the magnetos can be easily seen.
There are handy USB ports on both sides of the panel. These USB sockets supply the latest quickcharge specs.
There is no boarding step, or handhold, so getting up and into the cockpit requires a fairly high step up onto the trailing edge of the wing. You step down into the cockpit and slide across to the left seat.
Flying the Vansin
So how does the aircraft fly?
Start-up is conventional fuel injected Lycoming. Prime it, then pull the mixture back to idle cut-off. Remember to flip the two small mag switches to On. Crank the starter and when she fires, advance the mixture.
For the taxi, even with the extended nose, visibility is good for a taildragger. The rudder pedals are connected to the tailwheel and there is differential braking on all four pedals.
For takeoff she likes 15 degrees of flap. This helps to move the centre of lift back a bit and facilitates lift off. The wing incidence is only 8 degrees and this makes a flapless takeoff happen at higher groundspeed then is necessary.
She gets airborne at 45 kts indicated (KIAS) and the initial climb out is at 70 kts till 700 ft above ground when the flaps are retracted. At circuit altitude the fuel pump is switched off and 2400 rpm and 22” gives an indicated airspeed of 130 kts. Due to the 9.2 metre wingspan the wing likes to haul weight and once rotated she is buoyant and likes to fly, even with full fuel and two crew and some baggage. On airports with a high density altitude, the turbo can be applied to give sea level manifold pressure to give sea level performance. The turbo is seldom used in cruise because she has a healthy cruise speed.
At altitude a 2400/22 power setting is maintained, and the true airspeed then is 150 kts. Fuel consumption at that power setting works out to 32 litres/hr.
In the circuit she is very docile. Downwind is entered at 120 KIAS and the speed decreased to 90 KIAS, when approach flaps are selected. This speed is maintained on Base leg and the turn onto Final approach.
On Final speed is reduced to 60 KIAS and full flap is selected. The visibility over the nose is excellent and at these speeds and typical weight the approach is stable. I aim for 50 KIAS over the numbers.
She is easy to land and directional control is typical taildragger, but not at all jittery. Rudder authority is excellent.
The Vansin first flew in 1978, yet in 2020 she still is modern. The vision that Carel had wandering through his aircraft boneyard was way ahead of its time. He has created a unique aircraft, a truly one of a kind in the world.