Fokker S.13

S.13

Fokker S-13 Universal trainer

preliminary translation

The S-13 Universal trainer was developed as a navigation trainer and multi-engine trainer.

On December 13, 1946, representatives of the LSK, NIV and Fokker met for a meeting about the sales possibilities of the S.13.

It was determined, among other things, that there was a need for 123 copies for the Netherlands and the NE Indies with an annual supplement of 25 units.

The S.13 was a medium-sized all-metal low-decker, in the beginning the

S.13 two 450 hp engines. each and have a starting weight of 4500 Kg., with a price tag of 600,000 (guilders).

Both the LSK (Air Forces, predecessor of the Royal Netherlands Air Forces) and the NIV (the NIV was a branch of the NLL, National Aviation Laboratory and provided orders, financial resources and information in the field of aircraft development) contributed changes to the first design.

During the discussions that followed, consideration was given to making the design in question also suitable for the National Aviation School (RLS) and as a commercial aircraft for KLM.

It soon became clear that the LSK and KLM were so far apart in terms of the requirements that the aircraft had to meet that such a proposal offered no future.

The RLS also quickly dropped out.

After a number of changes to the S.13 design, the take-off weight was increased to 5500 Kg. and an engine power of 2X 600 HP was required.

When the prototype was virtually completed, the military side confirmed in writing on 1 June 1949 that “...it is by no means certain that the Air Force Staff will enter into negotiations with NV Fokker regarding the purchase of a number of S.13 aircraft. ...”

This letter therefore stated in so many words that there was no need for the S.13 at the LSK.

The LSK also did not buy a comparable aircraft abroad.

Under the MDAP programme, Mutual Defense Aid Program or Mutual Defense Assistance Programme, the United States supplied goods from its surplus from 1948 for the reconstruction of Europe after the Second World War.

For the LSK this meant that they could have access to many Beechcraft T-7 navigators and Beechcraft Model D-18 from the mid-1950s almost free of charge.

An attempt to equip an S.13 with floats and make it suitable for use in the Dutch East Indies was also unsuccessful.

Some of the photos and texts come from an unknown author from Amstelveen.
At the end of this page you will find a link to the PDF.

Click on the photo to enlarge the photo

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A hopeful drawing for an advertising brochure?
The S.13 came at an unfortunate moment, when (later) it turned out that the
United States planes of about the same size almost free
delivered in the MDAP program, Mutual Defense Aid Program or Mutual
Defense Assistance Program vanaf 1948.
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02

Notes from the scrapbook of one of our editors.
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03
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04

The Fokker designers also made a sketch/drawing of an S.13 version on metal floats as a seaplane, referred to as the S.13W.
This version had slightly different dimensions and reduced performance, mainly because of the floats that replaced the landing gear.
It was hoped (in vain) to arouse interest in allowing the aircraft to operate in this version in the Indian waters and those of New Guinea.
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05

Fokker praised the versatility and broad deployability of the S.13 in the national and international aviation press.
Not entirely unjustified, by the way, because the possibilities and deployability of the S.13 were endless.
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06

With sometimes minimal adjustments, the S.13 could be used for the following tasks:

• The carriage of passengers and/or mail.
• Training paratroopers.
• Training navigators.
• Training radio operators.
• Training air gunners and bomb aimers.
• Training observers.
• Training pilots on multi-engine aircraft.
• Training radar operators.
• Perform aerial photography.
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07

For navigator training there was a panel with the necessary instruments on the left side of the cabin.
A so-called Plexiglas astro-dome was mounted on the hull, which allowed the navigator to measure the vertical angle between a celestial body and the horizon with a sextant.

An extensive radio installation could be built in for the radio operator training.
The installation included VHF, Verry High Frequency, long and medium wave transmitters and receivers and a radio compass.

For the training of bomb aimers and observers, the S.13 was equipped with a Plexiglas nose turret.
The nose turret could be reached from the cockpit.
The appropriate instrumentation could be fitted for bomb aimers.
For the training of pilots on multi-engine aircraft, blind flying could be practiced by means of amber screens.
Because the S.13 was equipped with a nose wheel, take-off and landing could also be practiced with this configuration.
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08

Before construction of the prototype began, two Mock-ups had been built in 1948: full-size wooden models of the hull.
One Mock-up had no outer skin, so the structure was clearly visible.
The other Mock-up also had the center wing with nacelles. Customers could thus get an impression of what the S.13 would look like inside and out.
The Mock-up was also used to determine where to install certain installations and also to build the interior into the cabin.
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09

The second, uncoated, S.13 Mock-up.
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10

Wind tunnel tests were carried out at the National Aviation Laboratory in 1949 with a scale model of the S.13.
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11

The S.13 fuselage with center wing, rear right Mock-ups of the
S.13 and the S.14.
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12

2 × Pratt & Whitney R-1340 Wasp S1H1-G 9-cylinder air-cooled radial engines, 600 hp each.
Pratt & Whitney R-1340 Wasp
13

The plexiglass nose for the observer of the S.13
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Construction of the center wing of the S.13.
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15

The center wing, now clad in aluminum plating.
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The construction of the prototype of the S.13 started in mid-1949 in the Fokker factory in Amsterdam North, the S.13 received cn 6288.
March 11, 1950 preparations at Schiphol for the first flight.
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17

The PH-NDW ready for take-or run for the first flight.
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18

Fokker test pilot Hugo Burgerhout with Mr. As an observer, Coerkamp flew the first flight from Schiphol with the S.13.
The 32-minute flight revealed no problems, as did the second flight the next day, which lasted 35 minutes.
The plane showed excellent flight characteristics.
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The only malfunction that came to light during the test flights of the S.13 was a power failure in the intake lines of the carburettor, resulting in loss of power and sometimes even stopping the engine.
After a month the Dutch and British Pratt-Whitney engineers solved the power/carburetor problem.
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Hugo Burgerhout smiling in the cockpit on the platform after returning from the first flight.
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22

The PH-NDW parked on the platform in front of the Fokker hangar at Schiphol after the first flight.
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The S.13 continued its test program and on April 3, 1950 the S.13 was deregistered as PH-NDW and was given the pseudo LSK registration D-101.
The first flight with this registration took place on April 19, 1950, it was the 24th flight of the S.13.
Fokker test pilot Gerben Sonderman performed this flight, with four observers on board.
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After that, the S.13 with the registration D-101 flew for a while at the LSK on a kind of loan/test basis.
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On June 15, 1951, the S.13 received a civil registration again, PH-NEI, in the name of the NV Koninklijke Nederlandse Luchtenfabriek Fokker.
The first flight with this registration took place on June 28, 1951.
It was the 154th flight of the S.13 with Lt.Z. Venema as a pilot and Hugo Burgerhout as an observer.
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The S.13 also received a new paint scheme, gray on the underside and white on the top. with a red trim over the hull rising to the vertical tail.
After more than a year of flight tests and static tests, the S.13 received the certificate of airworthiness on June 28, 1951.
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27

Refueling on Texel.
The S.13 was quite thirsty.
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After having flown for more than three and a half years with Fokker and almost eight years with the NIV, the S.13 was donated to the TH-Delft in June 1961.
There the S.13 was included in the aircraft and aircraft parts collection of the Aeronautical Engineering department of the Technical University in Delft.
Unfortunately, the S.13 was soon sawn into small parts by the TH.

The photo is from 1961. The hull of the S.13 arrives in the study hangar of the TH-Delft. Later, another piece of the rear of the hull would be sawn.

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32

The tail section of the S.13 eventually ended up in the Aviodrome in Lelystad.
Here it is in storage in the T-2 hangar of the Aviodrome.
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34

The cockpit of PH-NEI.
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35
Click here for an overview of the instruments
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