1、Lessons Learned Entry: 1599Lesson Info:a71 Lesson Number: 1599a71 Lesson Date: 2005-04-29a71 Submitting Organization: DFRCa71 Authored by: Trong BuiSubject: Effects of Pressure Port Surface Irregularities on Flush Air Data System Measurement Abstract: The Dryden Aerospike Rocket Test Directors Discr
2、etionary Fund (DDF) project conducted flight research of an aerospike rocket nozzle design using high power amateur rockets. The standard nozzles in these rockets were replaced by the aerospike nozzles and the rockets are then flown with aerospike nozzles only. Two aerospike rockets were flown succe
3、ssfully to altitudes of over 26,000 ft and speeds of over Mach 1.5. To determine the incoming flight flow angles, a simple flush air data system (FADS) was used. The FADS system consists of four nosecone static pressure taps around the 10-degree rocket nosecone, clocked at 90 degrees apart. One of t
4、he static pressure ports, port 3, is in an area where there is a slight waviness on the nosecone surface finish, on the order of 0.005 in. As the results, port 3 static pressure measurements were consistently lower than the other three ports. Uncorrected, this resulted in an extra 1 degree of appare
5、nt flow angle at transonic speeds. Description of Driving Event: The slight waviness of nosecone surface variation in the vicinity of the FADS pressure port 3 causes the local pressure measurement to be lower than the other ports. Since the FADS pressure port measurements are used to compute the inc
6、oming flow angles, this results in an extra 1 degree of apparent flow angle at transonic speeds. Lesson(s) Learned: Surface waviness at the FADS pressure port location will change the local wall static pressure, resulting in additional apparent flow angles at transonic speeds. Recommendation(s): Pro
7、vided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-The area in the vicinity of FADS pressure ports need to be verified to be free of surface imperfections and waviness. Rub a finger across the pressure port in both directions. If no irregularities or wavin
8、ess is found, then the surface should be flush enough. Evidence of Recurrence Control Effectiveness: N/ADocuments Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Sciencea71 Aeronautics Researcha71 Space OperationsAdditional Key Phrase(s): a71 Accident Investigationa71 Aircra
9、fta71 Flight Operationsa71 Payloadsa71 Range Operationsa71 Safety & Mission Assurancea71 SpacecraftAdditional Info: Approval Info: a71 Approval Date: 2006-04-17a71 Approval Name: dkruhma71 Approval Organization: HQProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
