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Pathfinder Rocket

Designed and Built By University of Cincinnati
Casper College & Natrona County School District Students

Progress Report

Pathfinder Rocket
Successfully Launched

Pathfinder Home Page

Motor Static Test
Video/Photos

Progress Report

Launch Video & Photographs

Casper Students On Project

updated.gif - 0.2 K September 25, 2004 - The Pathfinder Rocket was launched on July 17 @ 7:17am EDT from the NASA Wallops Flight Facility. The rocket was launched at an angle of 10 degrees off of vertical.

Click here for a NASA Wallops Newsletter on the launch.

Based on data and video, the ignition of the solid rocket motor was as expected. The motor achieved full power at T+ 5.5 seconds. About halfway into the motor burn, the rocket started to pitch up and down. The fins were canted on the rocket to produce a roll rate of 4 Hz at burnout. Apparently, at around 2 Hz, the rocket went into pitch-roll coupling, which started the oscillatory pitch. This oscillation of the rocket dramatically raised the aerodynamic drag forces beyond those initially expected during the flight. Shortly after burnout, the rocket pitched violently up 90 degrees and then down 90 degrees. With the rocket traveling sideways, the entire rocket body acted as an air brake stopping its forward momentum. The high drag during boost combined with the "air brake" effect after boost caused the rocket to only reach a peak altitude of around 13,500 ft. After the rocket reached its peak altitude, the rocket went into a flat spin rather than coming down nose first.

The rocket was tracked by radar. Without a transponder on the rocket, the radar was only a "skin" track. It is apparent from the radar data that the radar was having a hard time locking onto the rocket. The metallized exhaust from the rocket motor seemed to be creating false returns resulting in the large data scatter. However, it was possible taking the altitude versus time and range versus time radar data and filter out the false returns. The estimated trajectory is shown below along with the "raw" radar data. The estimated trajectory shows a peak altitude of 13,500 ft with all forward momentum stopped shortly after motor burnout.

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Pathfinder Rocket Trajectory Based On NASA Skin Track Radar &
The Estimated Trajectory Filtering Out Radar Scatter

This correlates very well with the results from the FLIGHT trajectory software program. The initial launch angle along with the high drag coefficients corresponding to the oscillation of the rocket were input into FLIGHT. The results overlay the estimated trajectory during boost and show the rocket would have reached a peak altitude of around 21,000 ft.

Based on the motor pressure telemetry data, the motor action time was around 14 seconds. Due to the spinning of the motor during flight, the chamber pressure was much higher than it would have been if it had not been spinning. Pressure augmentation data for spinning ammonium nitrate composite propellant was not available prior to launch so spinning ammonium perchlorate composite data was used to estimate how much the chamber pressure could increase. Consequently, the motor was structurally designed to withhold chamber pressures far beyond its maximum expected pressure so that it would not fail in flight. Unfortunately, the actual chamber pressure exceeded what the flight pressure transducer could measure. However, preliminary estimates indicate the maximum chamber pressure was around 1300 psi. As a reference, the non-spinning, peak chamber pressure was estimated to be 916 psi.

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Pathfinder Rocket Trajectory Correlates With
FLIGHT Trajectory Software Prediction

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Pathfinder Rocket Clearing The Launch Rail


NASA Launch Log

    NASA Log Of Pathfinder Launch As Posted On Their Site
  • 1:30 p.m., EDT, Friday, July 16 - The launch of the University of Cincinnati/Casper College Pathfinder rocket is on schedule for Saturday, July 17. The launch window is 5:45 to 8 a.m. The countdown begins at 3:15 a.m. Launch updates on this site will begin at 4 a.m. If you are in the Wallops area, launch commentary can be heard on 760 AM. Also, launch updates before the start of the countdown are available on the Wallops Launch Status Line at 757-824-2050.
  • 4:05 a.m. EDT, Saturday, July 17 - The countdown is at T-1 hour and 40 minutes to the opening of the launch window for the launch of the Univ. of Cincinnati/Casper College pathfinder rocket. The launch window runs 5:45 to 8 a.m.
  • 4:30 a.m., July 17 - The weather is looking good for the launch this morning. On Wallops Island the winds are around 5 mph out of the southeast. The temperature is at 70 degrees. Clear skies. The purpose of the Pathfinder project is to give students hands-on experience in every aspect of engineering and launching a sounding rocket. The Pathfinder rocket is 19 feet long and 8 inches in diameter. Students from the University of Cincinnati designed and built the payload. Students from Casper College and Natrona County School District worked with Wickman Propulsion and Space, all in Wyoming, in the design and fabrication of the motor. NASA is providing design consultation, launch range and safety support for the project.
  • 5 a.m., July 17 - We are now T-45 minutes and counting on the launch this morning. The Pathfinder rocket is predicted to fly to about 30,000 feet altitude, which it should reach about 47 seconds after ignition. The rocket motor achieves burnout at 9 seconds after ignition. At this point the rocket is predicted to be at 9,800 feet.
  • 5:15 a.m. - The count is now T-30 minutes to the opening of today's launch window.
  • 5:50 a.m. - T-10 minutes and holding. We have been holding because of a boat in the impact area. The range has contacted the boat and is now moving to the north out of the impact area. The launch team is on the pad making final preparations for launch.
  • 6 a.m. - T-10 minutes and holding. The range continues to monitor the boat situation. The boat is moving. The launcher is now being raised.
  • 6:04 a.m. - The range is going to continue the count to the T-1 minute mark. The clock will be held at that point.
  • 6:09 a.m. - Approval has been given for the crew to install the igniter on the rocket. We are at T-5 minutes and counting.
  • 6:14 a.m. - T-1 minute and holding.
  • 6:20 a.m. - T -1 minute and holding. There is still one boat in the impact area.
  • 6:30 a.m. - The range continues to hold at T-1 minute. The launch window today closes at 8 a.m. Installation of the igniter has been completed. The pad is clear and ready for launch.
  • 7 a.m. - The range continues at T-1 minute and holding for today's launch. There is still one boat in the impact area. The range reports they expect it to be out of the impact area in about 10 minutes.
  • 7:05 a.m. - T-1 minute and holding. Range is expected to be clear in about 5 minutes. The preliminary launcher settings have been established.
  • 7:10 a.m. - T-1 minute and holding. Clear range expected in about 3 minutes
  • 7:14 a.m. - Impact area is now reported clear of boats. Final launcher settings have been established. Expect to pick up the count soon.
  • 7:16 a.m. - T-1 minute and counting
  • The rocket ignition sequence was initiated at 7:17 a.m. Launch occurred 2 seconds later. Preliminary apogee report shows the rocket reached 15,548 feet. The rocket impacted in the Atlantic Ocean as planned.
  • Student launch Posted by RCC on 2004-07-17 07:24:56 7:25 a.m.


Background Information

The Pathfinder rocket has passed two major reviews. They are the Mission Readiness Review (MRR) and a Range Readiness Review (RRR). During these reviews, students must convince NASA engineers that Pathfinder is ready for a safe launch. The Pathfinder rocket has already passed the MRR in March 2004. The review went well with only a few action items. The RRR for the Pathfinder rocket was held on July 8th.

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In preparation for the MRR, University of Cincinnati students conducted vibration testing on the rocket upper body tube and subjected the rocket fins to the worst case aerodynamic loads. The vibration tests on the rocket upper body were successfully completed the first part of January, 2004. The fin can (shown left) was completed in June and each fin was subjected to a load of 155 lbs to simulate maximum expected aerodynamic load.

During the last few weeks, the propellant for the motor was mixed and cast into the five propellant cartridges used to fuel the rocket motor. Afterwards, students trimmed excess propellant from the cartridges.