Pander S4 Postjager colors and markings

Around 2010 Execuform issued a 1/72 scale vacform model of the Postjager. A 1/72 resin model is expected before the end of 2012. I initially planned to build the Execuform vacform, and started researching the subject. For some time, the black and white photos confused me thoroughly. But patterns emerged slowly, and it is now possible to analyze the colors with just five photos. The result was slightly surprising.

Black and white film types

Color analysis of the Postjager markings

The red-white-blue fin tip shows clearly that this is an ortho photo: red is black, blue is rather light. (From: Hazewinkel: Pander - een Haagse vliegtuigbouwer, page 117)

This photo is clearly made with pan film: the red portion of the fin tip red-white-blue has a normal grey value, the blue part is slightly darker. Now look at the PH-OST registrations on the rear fuselage and the wings: they have a grey value, and are clearly not black. Since red and orange are the only colors that show this difference in ortho and pan films, they must be in that color range. Since they are lighter than the red part of the fin tip, they must be orange or orange-red. The Pander factory logo on the tail appears to be the same color. (From: Hazewinkel: Pander - een Haagse vliegtuigbouwer, page 113)

This photo does not offer a direct clue whether it was made with ortho or pan film. (From: Hooftman: Nederlandse vliegtuigencyclopedie - Pander S4 Postjager, page 89)

However, combined with this photo we can now be sure that the previous photo was made with ortho, and this one with pan. The different representation again shows us that the lower side was painted orange or red. Considering the grey value, orange is most likely. The ST lettering has the same grey value as the rest of the aircraft, and thus appears to be silver dope. Note that 'POSTJAGER' in large capitals on the nose is painted in the same color as the lower side of the wings - orange. (From: Hooftman: Nederlandse vliegtuigencyclopedie - Pander S4 Postjager, page 75)

This photo shows the demarcations of the orange areas on the lower side. Note that the tailplanes are also orange on their lower sides. (From: Hooftman: Nederlandse vliegtuigencyclopedie - Pander S4 Postjager, page 41)

Other bits of evidence

Circumstantial evidence that the lower side was (going to be) painted orange. The middle piece of text translates: "Topside the aircraft had the colour of aluminium and the bottom side will be painted orange' wrote De Rotterdammer newspaper on 1 October 1933. The latter never happened though." I don't think the last statement is correct, but the statement makes clear that the plans always were to paint the lower side orange. (From: Hooftman: Nederlandse vliegtuigencyclopedie - Pander S4 Postjager, page 45)

More details on the painting: the plywood was first painted with 'red paint' (maybe red oxide dope?) followed by English nitro-cellulose paint with aluminium powder. (From: De Ingenieur 8 december 1933 - Constructieve bijzonderheden van de Pander-Postjager PH-OST, page 227).

C. ter Horst, in 'De Modelbouwer' (June 1987) reports that the complete aircraft was covered with Madapolam, a bleached cotton fabric. This avoided the use of serated ('pinked') linen rib tape to cover joints in the wood structure, and ensured a very smooth surface. The beech plywood was Bakelite (phenol formaldehyde) bonded, a fairly recent innovation that made it waterproof and improved the durability greatly.

Wikipedia reports that Madapolam is a soft cotton fabric laid out in linen weave. It was famously used as the covering for the de Havilland Mosquito, tautened and stiffened with aircraft dope.

The finishing techniques of the de Havilland Mosquito make an interesting comparison: "The tailplane, and fin, as well as being wooden, were covered in wood, then Madapolam fabric. The fabric was treated to Scheme "Z," which consisted of two coats, of half-strength, followed by three coats of full-strength, red dope, followed by, at least one, but, often, two coats of light-reflecting aluminium (not silver) paint." A great photo of the application of the Madapolam fabric can be found on the webpage dedicated to William Herbert 'Bill' Grace (4/5 down the page).

Later I remembered that de Havilland also used fabric over the wooden fuselages of the Vampire and Venom. It is described in The History of the De Havilland Vampire. Photos of the wooden structure can be seen at Uschi van der Rosten's De Havilland Vampire References.

I tried to find more information about the practice of covering the plywood skin with fabric. I consulted the following references, but found almost nothing, suggesting it was not common.

General markings

Additional markings during the Indonesia flight

Additional markings during the London-Melbourne race

Modeling links

Drawing under construction

Starting with the Postjager drawing by C. ter Horst (NVM), I made a completely revised drawing based on research in archives. It's not done yet, so it's shown in a small size here.

Research links

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