Spillage Drag Estimation and Drag-Thrust Accounting for a Missile with Air Breathing Propulsion

• Main Author: Olsen, Jon
• Format: Others
• Language: English
• Published: KTH, Flygdynamik 2012
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-102075

Air intake related aerodynamic aspects of an air breathing cruise missile are analyzed. A method for thrust and drag accounting is established, and, based on that, a partial simulation model for the thrust and intake spillage drag force of the missile is developed. The model combines wind tunnel data with analytical data. The intake spillage force has two components, pre entry force and cowl force. The pre entry force can be computed relatively easily, while the cowl force depends strongly upon actual intake geometry and no general method exists. An approximate cowl force is computed based on available data. The accuracy of the cowl drag results is difficult to predict, as no complete theoretical model is available, and the partial models published cite no accuracy limits. The cowl drag results need further verification through wind tunnel tests or CFD analysis. However, spillage force results are produced that are in the magnitude of 30% of total drag, which is expected. Also, dependencies on known variables and trends are as expected. Finally, flight test profiles in order to validate the model are suggested.