RNLAF/NLR flight test for certification of Lockheed Martin Overseas Corporation Enhanced Targeting Pod and BAe Systems Falcon Owl Navigation Pod

RNLAF/NLR flight test for certification of Lockheed Martin Overseas Corporation Enhanced Targeting Pod and BAe Systems Falcon Owl Navigation Pod

Haringa, M.J.
Meijer, J.J.
Rijzebol, K.R.

National Aerospace Laboratory NLR

2001-07-31

The Royal Netherlands Air Force has carried out an analysis and test program with the F-16A/B (Mid Life Update version) aircraft for the airworthiness certification of the Lockheed Martin Overseas Corporation "Enhanced Targeting Pod" and the British Aerospace Systems "Falcon Owl" navigation pod (earlier known as "Atlantic" Navigation pod). Structural loads. Flight handling, and mainly the subjects Flutter and Limit Cycle Oscillations and finally Store separations are addressed in this document. Analysis of structural loading of the aircraft in the external stores configurations and under the operational conditions showed no overload cases. Ventral fins were instrumented to investigate loads and vibrations due to the addition of inlet mounted pods. Comparison of configurations with the navigation pod or targeting pod, with configurations without the pods, showed increases in vibration levels; the most on the targeting pod side. As a consequence the chance of fatigue damage to the ventral fins will increase. Flight handling was analyzed and flight tests were executed. The results of this analysis were that the impact of the pod(s) on the departure sensitivity was minimal within the defined operational envelope of the aircraft. Significant deterioration was only found well outside the envelope. To verify the analysis, test flights in "worst case" external store configurations, without and with pods, were dedicated to verifying the flight handling characteristics. The results confirmed the analysis; in general they were judged "satisfactory". Configurations with substantial asymmetric loads showed unacceptable flying qualities when rolling maneuvers were initiated at negative normal load factor (inverted flight). However, such operations are excluded in the aircraft's flight manual. Simulations and earlier flight test results were used to analyse flutter and Limit Cycle Oscillation behavior. In this analysis no significant influence of the pods on the flutter / Limit Cycle Oscillation behavior was found. Further flight tests in a number of worst case configurations confirmed the analysis results. Some configurations, however, were considered not acceptable, both with and without pods, and were not certified; other configurations were certified with restricted flight envelopes. Analysis of earlier separations of 370 gallon wing pylon tanks (Royal Netherlands Air Force and United States Air Force) showed that addition of the navigation pod would have minimal effect on the tank separations. Three test flights have been executed in order to establish possible influence of inlet mounted pods on the separation behavior of wing pylon tanks. The tanks were released at identical flight conditions fi^om the left wing in three different configurations of which two with the Falcon Owl pod. All three tanks made contact with the left ventral fin on the aft fuselage of the F-16 test aircraft. The tests and analyses showed that: • The Falcon Owl navigation pod does not significantly change the trajectories of the released 370 gallon pylon tanks. • Adding the Falcon Owl pod does not affect the tank jettison limits. • The 370 gallon tank released from the left wing of a certified configuration without the Falcon Owl navigation pod struck the ventral fin in conditions under which a previous, USAF certification flight test program showed a clean tank separation from the right wing. • Because of the left tank - ventral fin interference problem new tank jettison limits are issued by USAF/SPO/F-16. The new limits are adopted for the RNLAF F-16A/B with the Enhanced Targeting Pod and the Falcon Owl Navigation Pod. The investigation into the left tank - ventral fin interference problem is a separate task, not related to the Falcon Owl pod, and of a general concern to the F-16 user community. An initial comparison of left hand and right pylon tank releases indicates that there is difference in tank separation trajectories for LH and RH tanks. Paper presented at the 2001 Aircraft-Stores Compatibility Symposium, Destin, Florida, USA, 5-8 March 2001.

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Nationaal Lucht- en Ruimtevaartlaboratorium

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NLR Technical Publication TP 2001-327

Aerospace Engineering Reports

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(c) 2001 National Aerospace Laboratory NLR