The Royal Netherlands Air Force (RNLAF) intends to keep its F-16s operational until 2025. NLR provides the RNLAF with technical and operational support to achieve this.

Until the F-35 is available, we will keep the F-16 operational as long as possible and will ensure that the fleet continues to meet the RNLAF’s operational demands. To achieve this, NLR is conducting various projects, including a series of unique tests for the F-16 wing and a project involving the radome, which covers the radar antenna.

With the test programme for the F-16 wing, the Ministry of Defence and NLR intend to establish whether the wings of the F-16 will reveal unexpected damage during the remainder of its operational lifespan. The test programme is unique in that it allows the Ministry of Defence to proactively gather information on the state of the F-16 wing. This allows the Ministry of Defence and NLR to predict the technical end of life of the wings. NLR developed a special rig in which an F-16 wing was subjected to a spectrum of fatigue loads, consisting of variable forces representative of those encountered during real RNLAF missions.

NLR has validated models and a wide array of data that are used to determine the load spectrum. The test aimed to grow tiny cracks so that they became visible. This generated information on which areas of the structure are most critical (and possibly require modification) and how quickly fatigue cracks grow (giving an indication of inspection frequency), as well as the realistic lifespan of a wing.

The radomes on F-16s and helicopters may be damaged during intensive operational use. This damage, as well as incorrectly executed repairs, can cause errors in the radar system, which may result in lower protection levels for the aircraft and pilot. The Ministry of Defence therefore asked NLR to establish a National Technology Programme (NTP) that develops mathematical models for the electromagnetic performance of the nose radomes of aircraft and helicopters.

The mathematical models will be used for the analysis of radomes consisting of inhomogeneous layers; i.e. consisting of layers that differ in thickness and material used. These models will allow the inspection of complex radome shapes (i.e. not flat, but rounded or conical). The same goes for the single and multiple reflections that take place within the radome before the radar signals pass through the radome. To arrive at a viable mathematical model, NLR made use of electromagnetic (EM) mathematical models, facilities for the measurement of situational conditions and its EM facilities for measuring the impact of the radome on the antenna. This project, called SEMINAR, will be rounded off in mid-2015.