Let Let Let – Warplanes

When Germany capitulated in May 1945 and German troops left the Netherlands, there was not much left of the national aircraft industry. The Fokker works at Amsterdam-Noord were practically destroyed and any equipment still left was looted by the retreating German forces. Also the Fokker workshop at Schiphol-Airport was practically non-existing by that time. Much work was done during the ‘Wederopbouw’ (Reconstruction) of the Netherlands and the Dutch industries and one of these projects was the resurrection of the Fokker works. They started in simply built draughty sheds with contract work like refurbishing Harvards and Tiger Moths for the national aviation school. Later this was supplemented by the assembly of Hawker Seafuries for the Marineluchtvaartdienst and Gloster Meteors for the Koninklijke Luchtmacht.

However, the most important starting order was the construction of a few dozen gliders for the various Dutch glider clubs to replace the planes that were robbed by the Germans during the war. Fokker constructed German types: the single-seat E.S.G. and the dual-seat Göppingen Gö-4II trainers as well as the Grunau Baby single-seater. Fokker also constructed a few DSF Olympia high-performance gliders. This order was essential for Fokker since it enabled them to select and train qualified aircraft constructors for their next project! This next project was the S-11 elementary trainer, which was taken into production in 1950. The Fokker management realized soon the importance of the newly introduced jet engine and already in 1946 they presented at the Paris Air Show a model for a future small 17-seat twin-engine jetliner powered by two fuselage-mounted Rolls-Royce Nene engines. Designated as the F-26 Phantom, it was never built, but it gave Fokker designers at least some experience with this new way of propulsion. After the F-26, Fokker started the design of an advanced jet trainer to make future pilots accustomed to jet propulsion and high Mach numbers. What Fokker had in mind was an advanced jet trainer that would be used by air forces within and outside Europe to train their future jet fighter pilots. As we will see in this article Fokker’s success was only limited…

How it started…

At the final founding of the post-war Fokker aircaft works ‘N.V. Fokker’ on 1 January 1947 and with the Fokker S-11 elementary trainer as first military project, the Fokker management started with the design and development of an advanced jet trainer. Fokker was commissioned with this project by the Dutch institute of aircraft development NVI (Nederlands Instituut voor Vliegtuigontwikkeling). The new jet trainer was intended for the training of future Dutch jet fighter pilots. Under Ontwerp (=design) 240, the Fokker team came up with various design alternatives.Final design selected was Ontwerp 240K and work on a prototype was soon started. Although in the final design a side-by-side layout for the pilots was selected, Fokker also studied an alternative (Ontwerp 204J) with the pilot seats in tandem, but this was finally rejected. Already on the 1949 Paris Air Show Fokker showed a model of the new Machtrainer. Receiving the type designation S-14, it was in fact the first jet-trainer in the world designed as such. All jet trainers at that time were strictly two-seat versions of already existing jet fighters! Since it was intended to make future jet pilots familiar with speeds at high Mach numbers, it was appropriately named the ‘Machtrainer’. Work on the prototype was started in the old Fokker plant in Amsterdam-Noord at the Papaverweg. The fuselage front and centre section with the wings and the tail section were built as separate units which were transported by barge to the Fokker workshop at Schiphol airport for final assembly. Also the engine was installed here. All work was completed on 19 May 1951 when the plane was ready for its first test flight carrying Dutch military markings and the registration K-1.

Some technical details…

The S-14 external characteristics were short, broad and slightly tapered wings that gave it soon its nickname ‘ the Plank’. Further it featured a fuselage with mostly a circular cross-section and a nose-mounted air intake. Air was split in two ducts going alongside the cockpit section and feeding a centrally placed Rolls Royce Derwent jet engine. The exhaust was fitted in the tail using a long exhaust pipe. Places for instructor and pupil were side-by-side. There was more than enough space behind the two seats for an extra third backseat, although this was never done in practice. Both occupants were seated on Martin-Baker ejection seats. Construction of the S-14 was a semi-monocoque all-metal fuselage and all-metal wings and tail-planes. As a novelty, skin panels were not only riveted at the production model, but also partly glued using a new bonding process developed by Fokker under the supervision of Rob Schliekelman. The bonding process was later used on a far more extensive scale on the F-27 Friendship! Further, the S-14 had a forward-retracting nose-wheel and a wide-track inward retracting main undercarriage. It also had a triple airbrake at the fuselage rear. Instead of the more usual hydraulic systems the S-14 systems were operated pneumatically. The S-14 was designed in such way that maintenance was simple with all internal places easy to access using several inspection hatches. In fact some inspection hatches were so big that a mechanic could easily crawl inside! It was also designed in such way that the engine could be easily replaced in a very short time.

Early flight testing…

On 19 May 1952, Fokker test pilot Gerben Sonderman made the first flight in the prototype K-1. However, this flight was very short because the main undercarriage wheels could not be fully retracted. Sonderman lowered the wheels again and made a safe landing. After some repairs, Sonderman tried again. Now the wheels retracted perfectly, but on the landing approach Sonderman noticed they refused to come down. He made a perfect belly-landing on the grass alongside the concrete runway and damage was only minimal. After these setbacks, the test program proceeded much better and on 15 June 1951 the S-14 could be proudly presented during the Paris Air Show at the Fokker stand inside the exposition hall, where it attracted much interest. The S-14 was transported to Paris by truck after wings and fuselage were separated. There were no further problems with the flight test program and already in January 1952 the Secretary of State from the Ministry of Defence announced their intention to place an order for 20 productions S-14′s for the Koninklijke Luchtmacht (KLu). This was later that year confirmed by a final order.

Test pilot Sonderman had the following remarks on the S-14 flight characteristics:
-at stall the nose drops after heavy buffeting
-the plane was not easy entered into a spin and actually had to be put into it. Normal recover could be obtained within one turn!
-at high Mach number (ca. 0.83) there was an uncontrollable wing drop during heavy buffeting which could be corrected by throttling down and applying the dive brakes.

Related posts:

1. Fokker S-14 Machtrainer by Nico Braas and Willem Vredeling
2. Climb
3. Fokker T.V “Luchtkruiser’ History, camouflage and markings
4. Fokker D-VII used in the Netherlands
5. Fokker D.XXI history, camouflage and markings

Pages: 1 2 3