Building the “Challenger II "


We had been happily flying our old Mx II at Tanjong Laboh for already 10 months, when Jon came along and loan us a VHS cassette video. It was part of an information package that included brochures from the manufacturer of the “Challenger” ultra-light. In screening we found it not only captivating but strongly convincing to an extent that kept our eyes firmly glued to the TV console and our mouth drooling. The opening scenery was a flight demonstration by a dealer named Don Zank on a very fast clip-wing Challenger II. Then followed by a long-wing version Challenger II flying low over the meadows to the lively tune of “Oh what a wonderful world” by Louis Armstrong. It was exceptionally exciting, like a block buster thriller and it was an immediate “hit”. The impact was obvious we immediately fell head over heels in love with it and had driven me to look for my cheque book. I guess had it not for been for Jon our lives would not have changed at all. We would not have progress as we were at that time quite contended flying our old faithful machine.

The model that we were interested was the long wing “standard version” mounting a Rotax
503 engine that functioned as a pusher, driving a 2 bladed wooden propeller. The two-place trainer with tandem seating arrangement with condition for the pilot to fly only from the front seat. It had high wings supported by struts and with tricycle undercarriage made up of two main wheels and a front nose-wheel; a departure from the traditionally tail-draggers. The advantage was better visibility and good ground handling. The fuselage was covered by stits and as for the wings, tail sections it was covered by mylar (a protective laminated fabric) sailcloth. The fibre-glass nose-cone provided a streamlined and aerodynamic look that helps to reduce drag. The engine hung under the lower part of the wing root-tube near to the trailing edge.

In the early years the impression of a ultra-light or also known as micro-light was that it was not meant for long distance traveling. It was a fun machine for you to enjoy flying around your backyard. That was a misconception and with the advantage of newly found advance technology, the design and the power-plant of the micro-light had excelled by leaps and bounds And as the years went by engine reliability had improved constantly enabling it to fly faster and further away. That was proven beyond reasonable doubts when 3 Challenger II pilots flew across from Wisconsin all the way to attend the “Sun & Fun 88” held at Oshkosh. The trio headed by the boss and designer Dave Goulet with 2 other colleagues Zank and Coriston made a historic round trip of 2,200 miles. It was an extra 400 miles for Zank as he was furthest away. They won the special “Flight of Distinction Award”

Finally we unanimously agreed that the Challenger II was our choice as the best plane at that time available in the market. Generally it was good looking with clean lines and has
excellent handling qualities. Most important of all; the price was reasonable and affordable to us. Anyway around November 1993 I recalled rushing to Citibank at Shenton Way and banked in the sum US$ 7,608.00 as the final of the second half payment. The Challenger II had costs around fourteen thousand US dollars excluding airfreight and handling charges. That day David Leong and myself became the proud co-owners.

The shipment arrived Singapore on the 7th December and was later delivered to Jon’s
bungalow house at 45 Watten Estate. The garage was allocated to us as our sanctuary
for undertaking our sacred mission. The next few days we were seriously pre-occupied
in digesting our Builder’s Manual which we regarded as our Holy Bible. However when we did opened the wooden crates we found them packed with an assortment of aluminum tubes, sail-cloth, tyres and numerous smaller items. It took us quite a while to sort out on what we needed to begin with. For export purposes we received what was known as the “Knock-down version”. It meant that the main frame had been temporary built and then disassembled so that it could be packed into the wooden crate for shipment overseas. The major part like the fuselage lower frame came already pre-assembled to ensure alignment. The pre-drilled holes were found at the joints. The stays or down tubes were collapsed to save space for packing purposes. Upon receiving all we had to do was to up-right it into position and pop the rivets at the ready-made holes. The Challenger still qualified as a kit according homebuilt rules of being 51% factory built and 49 % the builder.

Of course from time to time we encountered problems, however Jon and Rick managed
to resolve by making a few overseas calls to Dave Goulet. As we progressed we were rewarded as the skeletal frame assumed the form of a fuselage. And for sake of good order a technical adviser was engaged for his expertise and step by step guidance in the building process.

Jon ironing the stits wing-tip

The stits covering job devoured a lot of time as we had to glue carefully the pre-cut fabric to the frame and allowed hours of drying time. The ironing was the best part, was fascinating as the fabric shrunk instantly. And before our eyes, it smoothens out the wrinkles thus tightening the fabric. It was like magic and we were immersed in our ironing, a job everybody wanted. It had the effect of addiction and obviously there was no shortage of willing hands.

As it took shape it drew the attention of inquisitive eyes of many who wondered what we were building. It looked like a helicopter or a gyro-copter as we had not fixed the wings and tail sections. David Leong a mechanic by profession did the mounting of the Rotax engine, working feverishly on the wiring and the electrical parts. We followed religiously the ‘progress chart’ and also kept a photographic record of what we did. The wings were done by attaching the vertical and diagonal stays to the leading and trailing edges and sock-on the mylar sail cloth. Then finally insert the ribs into pre-sewn channel pockets to strengthen the wings.

What is it, a gyro-copter ?

As for the fiberglass nose-cone we attached to the front of the fuselage and installed the wrap-around lexan front windshield and with the 2 windows provided full enclosure. The fixing of other ready-made pieces such as the dorsal fin, 2 horizontal stabilizers and 2 elevators was not a problem. We opted for a 10-gallon fuel tank to take the advantage of a longer range. The next job was the spray-painting and we had to do properly so as to transform our bird into a beautiful piece of art. Pre-painting preparation on the fuselage had to be carried out with wet-sanding to remove the rough layers to transform into smooth surface. We hooked up our newly acquired brand new air-compressor and begun the cosmetic ritual of the making up. It was a serious act of deception in covering up unlikely or defective spots to look good. Therefore extra care was taken in mixing the paint correctly in accordance to the appropriate portion. Then adjusting the control knobs accordingly and just shoot.

By working over the fuselage horizontally the primer coat looked great and as we went over again it became a lot better. We took a step back and admired the results and felt greatly satisfied. We applied 2 coats of ultra-violet paint for protection against the wicket elements and finally the two finishing coats of glossy white. In all we had spent some 170 hours working about twice or trice a week and took about two months. Finally when it was ready I arranged the Batu Pahat Transport Company for a pick-up. We loaded up our master piece on to the truck and I climbed on board joining my charge. I wanted to be doubly sure that it would be safely transported to our destination Tanjong Laboh airfield. At Bukit Panjang we stopped to pick up some customs documents and headed for the causeway and the Johore Bahru check-point.

Fortunately we cleared at Customs checkpoint without any problem. Luckily I followed because that crazy Malay driver was out of his wits and was traveling along the highway at break-neck speed. There was total absence of responsibility on his part of what was happening behind; he had taken things for granted. At high speed the effect of the wind flow had generated enough force to toss the 2 wings up and down. And as the wings were lashed on either side of the lorry I had a tough time trying to figure out which one deserved more attention. At times I had to knock the cabin top of the driver’s side cursing and swearing to draw his attention to slowing down. After much anxiety we arrived at our sacred playground in one piece, a sigh of relief overcame me. I could have gone down on my knees and kiss the ground for our safe arrival.

On the 15th January we were back again at Batu Pahat and checked-in the Government
Guess House locally known as “Rumah Persinggahan” . We had some un-finished task
to fulfill and meantime we wanted a comfortable lodging for our period of stay. Early next morning we were at the Tanjong Laboh airfield and got on the job of fixing the wings and the tail feathers of our beautiful bird. We also had to do the weights and balance to ascertain the C of G, the center of gravity.

Engine test at Tanjong Laboh.


And another day to test the Rotax 503 in a ritual known as “Breaking-in the engine”
It lasted one noisy hour and went on something like 5 minutes at 3,500 rpm then stepped
up to 5,000 rpm for one minute and so on. We had to follow precisely as according to the
Chart. By the end of the process we were stone deaf from the constant screaming of the 2
stroke engine at close quarters.

Jon was the test pilot and he happily took her up for a series of manoeuvers to feel the
controls and to identify any malfunction in order to rectify it. The Challenger displayed
exceptional qualities especially for it’s unique power-off soaring capabilities. All the 3
control axis were responsive and coordinated turns were easy. The stalls were very gentle
with no tendency to drop a wing and spiral down. Above the pilot’s head a lever controls the flapperons which is a combination of flaps and ailerons. To operate it you have to whine it clock or anti-clock wise for rise or drop position. The Challenger could be slowed down to about 22 mph for landing in short fields.

Finally the time has come and we are about to enjoy the fruits of our labour. Our reward
a wonderful flying machine that would make our dreams come true. It would open a new chapter in our world of micro-light flying and thus fulfill my air cadet motto of “Venture - Adventure”

Challenger II in flight over Johore

Specification:-
Aircraft: Challenger II
Country of origin: USA
Specification: 2-place tandem trainer (Standard version)
Wing span: 1 ft 6 ins
Length: 20 ft 0 ins
Height: 6ft 0 ins
Wing area: 173 sq ft
Power plant: Rotax 503 (52 hp)
Empty weight: 300 lbs
Useful load: 500 lbs
Ultimate load factor: + 6 - 4

Performance
VNE: 100 mph
Top level speed: 75 - 90 mph
Cruise speed: 65 - 75 mph
Stall speed: 22 mph solo / 30 dual
Climb rate: 1200 fpm solo / 700 dual
Take-off roll: 100 ft solo /200 ft dual
Glide ratio: 11 to 1 solo / 9 to 1 dual
Service ceiling: 14,000 ft solo / 12,500 ft dual
Fuel consumption cruise: 2.3 gph solo / 4 gph dual.