1、Lessons Learned Entry: 1621Lesson Info:a71 Lesson Number: 1621a71 Lesson Date: 2005-04-29a71 Submitting Organization: DFRCa71 Authored by: Trong BuiSubject: Protection of Rocket Chamber Pressure Transducer Sensing Port Abstract: The Dryden Aerospike Rocket Test Directors Discretionary Fund (DDF) pro
2、ject 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 successfully to altitudes of
3、 over 26,000 ft and speeds of over Mach 1.5. The flight data acquired during the flight tests were stored onboard and retrieved after the rockets were recovered. The rocket chamber pressure was one of the mission-critical onboard measurements. During the first rocket launch, hot rocket exhaust gas w
4、as allowed to impinge directly inside the rocket chamber pressure transducer sensing port. Even though the pressure transducer was designed to survive hostile environments and remained operational, the high gas temperature caused it to produce pressure readings that were erroneously high for the fir
5、t two seconds of rocket motor firing. During the second launch, silicon vacuum grease was used to pack the pressure port. This shielded the pressure sensing port from the hot gas impingement, and good rocket chamber pressure measurements were obtained. Description of Driving Event: After solid rocke
6、t motor ignition, the hot rocket exhaust gas traveled through the rocket chamber pressure transducer port and impinged directly on the stainless steel sensing diaphragm, causing the pressure measurement to be erroneously high for about 2 seconds. Lesson(s) Learned: Direct impingement of hot rocket e
7、xhaust gas can cause a pressure transducer to produce erroneous measurements temporarily. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Recommendation(s): Pack the sensing port of the pressure transducer with silicon vacuum grease to shield the pre
8、ssure sensing diaphragm from high temperature gases. The grease allows the pressure to be transmitted to the sensing diaphragm, but it insulates the pressure sensing diaphragm from the high temperature gas. Evidence of Recurrence Control Effectiveness: Good pressure measurements were obtained during
9、 the second rocket flight with the silicon vacuum grease packed inside the rocket chamber pressure sensing port. Documents Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71 Sciencea71 Aeronautics Researcha71 Space OperationsAdditional Key Phrase(s): a71 Energetic Materials - E
10、xplosive/Propellant/Pyrotechnica71 Flight Operationsa71 Payloadsa71 Pressure Vesselsa71 Safety & Mission Assurancea71 SpacecraftAdditional Info: Approval Info: a71 Approval Date: 2006-04-12a71 Approval Name: dkruhma71 Approval Organization: HQProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
