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Like any air force, the Dutch Air Force uses many expensive and delicate spare parts that have to be shipped all over the globe. It is therefore important to package these parts well to protect them against moisture, vibrations and shock.
The Dutch Air Force (Koninklijke Luchtmacht) used rubberized hair as a shock absorbing material. Rubberized hair had been around for upholstery since the 1930s. In the 1960s it was applied so often by the Koninklijke Luchtmacht that a special calculating disk was designed to figure out how much rubberized hair is needed for specific shipping circumstances.[1]
The disk is bilingual. Some scales are labeled in English and some in Dutch, for which a translation is added here in square brackets.
From the rim to the center the scales are: gewicht[weight] item (kg) / weight (lbs) / valhoogte[drop height] (cm) / drop height (inch) / aantal lagen rubb. hair[number of layers of rubberized hair] / inches cushion thickness / draagvlak cm2/ bearing area sq.inch / gevoeligheidsklasse[sensibility class] I..VI / g-waarde[g-value]. The disk also indicates in which circumstances polystyrene foam should be used instead of rubberized hair. The disk is labeled “Rekenschijf voor schok- en trillingwerend materiaal ‘rubberized hair’ vlg EVV 005 (dikte 4 cm).” This means that the disk can be used for rubberized hair as shock- and vibration-resistant material.
The rubberized hair used by the Dutch Air Force was standardized by the Economische Verdedigings-Voorbereiding [Office of Economic Defense Preparation]. The standard specified layers of 4 cm thickness. That is why the Dutch thickness scale is expressed in number of layers while the English scale is in inches cushion thickness. The g-scale expresses the maximum deceleration the item can withstand in units of standard gravity and it directly linked to the sensitivity scale.[2]
The Dutch Air Force claims that the introduction of standardized rubberized hair and optimizing its use by means of the calculating disk resulted in annual savings of ƒ32000 ($9000 in 1968). This amounted to a whopping 0.001% of the annual Dutch Defense Department budget.[3]
I have never seen the disk in real life, and it is not mentioned in the catalogs of Dutch military museums.
Figure 1. Calculating disk for rubberized hair, from De Militaire Spectator (1968) p.377
References
References
J.J. van Ravensteijn, "Kwaliteitsbehoud werkt kostenbesparend", De Militaire Spectator (1968) p.374-378.
Miljoenennota 1968 (Zitting 1967-1968 - 9300), published 19 September 1967, page 95
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