This was a great weekend to fly rockets!  Friday was a bit windy but otherwise a very nice day.  Saturday was pretty much perfect!   Low winds and very nice conditions all day long.  The crowd on Saturday was estimated to be well over 100 people and there were lots of nice flights.

On Saturday I (Vern) launched Starfire on an AMW M2200 "Skidmark" motor along with six out-board J-motors that were supposed to be air-started in two sequential sets after main motor burn out.  A first set of four and then a second set of two.  Unfortunately, only the second set of air-starts lit.  The reason the first set got skipped is still being investigated but the leading candidate for the likely cause is that there was simply not quite enough current to fire the four motors in the first set all at once.  The rest of the flight went just fine and Starfire was safely recovered after reaching 5,316 feet.  This was the 13th flight of Starfire!  It carried an on-board camcorder as well as two digital still cameras.  The video and the photos from the flight are presented below.

On Sunday Angelfire successfully flew on an Aerotech L952 motor to 5,367 feet.  My GPS radio downlink electronics and an ARTS recording altimeter were both on-board for this flight.  The data from them along with some photos of the flight are further down on this page. 

Friday and Saturday at this launch were devoted to commercial motors and then Sunday was reserved for research motors.  However, with the new TRA research rules adopted this year, commercial motors can now also be flown at research launches provided the member is certified TRA level 2 or higher.  I certainly think this is a welcome change to the rules and should help alleviate some of the contention that has been building between the commercial and research flyers.

Photo by Vern Knowles

As you can see it was a perfect day for flying rockets!  This view of the Brothers launch site is looking at the back side of the flight line from the hill used for the away cell.  It was taken on Saturday.   The standard high power pads are out beyond the other side of the flight line.

Click here to see a large high resolution panorama.    (1.7 MB file.)

Click here to see a smaller low resolution panorama.  (200 KB file.)

Here is another view of the back side of the flight line and high power pad area as seen from high in the air on Saturday.  This photo was taken by a digital camera onboard Starfire.

The flight plan for  Starfire was to liftoff on an AMW M2200 "Skidmark"  motor and then once that burned out, air-start four Aerotech J350 motors and once they burned out, air-start two Aerotech  J570  motors.   This is a total of 11,245 NS which is in the "N" class impulse range.  The on-board timer was set to fire the first set of air-starts at 4.0 seconds and the second set at 7.0 seconds after liftoff.  These setting assumed it would take the motors about another 0.5 seconds to come up to pressure.  All this should have pushed Starfire up to just about 10,000 feet.

The liftoff on the M2200 Skidmark was spectacular, but then after burnout, it soon became obvious that something was not going per plan with the air-starts.  Starfire was coasting upward nicely but had passed the point where the first set of air starts should have ignited and was rapidly approaching the point where it would be better if the air-starts never lit.  However, just then, some did light and Starfire picked up speed and headed up even higher.   From the ground it was not possible to tell exactly what happened, but after recovery it was obvious that the first set of air-starts never lit and what did go was the second set.  Fortunately, the 7.5 second delay to the second set of air-starts was still within the vertical coasting time of the rocket even when the first set never fired.  Definitely something to keep in mind when planning flights with sequenced air-starts!

The cause of this malfunction is still being investigated.  At this point the leading candidate is that there was simply not enough current to fire the four motors in the first set of air-starts all at once.   Starfire has ignited three motors at once in past flights, but not yet four.  Subsequent ground testing has shown that four is very marginal and only provides about 0.6 amps per igniter.  This is not the required 1.0 amps that will guarantee the Daveyfire N28F igniters will fire. 

Starfire carries a mini-DV camcorder in the lower payload bay and a module with two digital still cameras in the upper payload bay.

Jim Purcell looks on as I prep the digital camera module carried in the forward payload bay of Starfire.  The camera module is dumped out at apogee and the digital cameras begin taking lots of aerial photos during the ride down on the parachute.

Click here to see information about the camera module itself.

As usual the Skidmark motor was a real treat to watch and to hear!  Once you experience one of these motors it will become an instant favorite.  They are very loud and produce lots of smoke and lots of sparks.   A real thrill to watch!

Starfire Liftoff

This sequence of eight images shows the Starfire liftoff as a series of still photos taken 200 ms apart.   Click on the images at the left, or on the link below, to view them in a larger size.  There are also some videos further down this page, but these images are a bit more detailed and give a good look at the liftoff.   The titanium metal sparks were raining down all around the launch pad!

Starfire at apogee and immediately after the deployment charges have fired and separated the two halves.  Smoke from the ejection charge is coming from the forward airframe as tracking smoke is still streaming from the main motor.  The parachute is still wrapped in protective Kevlar but will be opening very soon!

Upper left is a view looking northwest.   Upper right is a view looking due west.  The Three Sisters peaks can be seen in the distance in that photo.

Starfire landed safe and sound exactly 0.47 miles from the flight line.

This was the 13^th flight for Starfire and this flight was successful in every way except for the fact the first set of air-starts never lit.   I'll get that problem fixed and try again!

Many thanks go to Chris Beekman for helping me recover Starfire and especially for helping to carry it back!  

Photos from previous Starfire flights can be found here.

Unfortunately, this time the onboard camcorder was unable to tolerate the G's at main motor ignition and also when the air-start motors ignited.  The video image was momentarily lost at those times.  Still, it's a fun ride, so check out the rest of the onboard video right here.

View High Resolution MPEG2 version     (28 MB)

View QuickTime version of the video     (22 MB)

View low res Windows Media Player version   (6.9 MB)

This short ground video of the launch was captured by Mike Moore.  It gives a very good view of the extended duration between main motor burn out and when the air-starts ignited. The first set of air-starts (due at 4.5 seconds) never lit, so it is the second set of air-starts you see in this video.

View High Resolution MPEG2 version   (5.1 MB)

View QuickTime version of the video    (4.0 MB)

View low res Windows Media Player version   (3.7 MB)

This is a short video of the liftoff as recorded by the "pad cam" setup about 100 feet from the launch pad.

View High Resolution MPEG2 version   (3.9 MB)

View QuickTime version of the video    (3.3 MB)

View low res Windows Media Player version   (1.0 MB)

My plan for Angelfire was to fly on an Aerotech L952 motor.  Ten years ago was the first "L" flight I had ever seen and it was on an L952.  It left a big impression on me and that motor has always been kind of a personal favorite ever since.  However,  I had never actually flown one, just admired them on other flights.  That was now going to change!   Angelfire is just a bit heavy for this motor, but with a 12 foot launch rail, all the simulations said it should be okay.  I was really looking forward to this flight.  The flight was going to be low and slow but that was okay with me.  It's a nice way to enjoy the power in the motor. 

Everything on this flight went well except that the main parachute was accidentally deployed at apogee.  The flight data indicates that the rocket was going nice and slow at apogee, but there is a 12.3G acceleration spike about 2 seconds after the drogue ejection charge fired. The spike is only 100ms in duration.   I believe that this is the point where the tubular nylon recovery harness ran out of slack and suddenly came tight.  This shock pulse was apparently large enough to break the nosecone shear pins and allow the main chute to tumble out.   The actual main parachute ejection charges were seen going off on schedule as Angelfire descended through the region of 800-1000 feet above ground.  I have some ideas for preventing this on the next flight so stay tuned!

Angelfire carried both my GPS radio downlink electronics and an ARTS recording altimeter on this flight.  The GPS system transmitted good data to the ground during the entire flight.  This allowed the entire flight trajectory to be captured and it is presented in a simulated 3D view further down this page. 

This was the sixth flight of Angelfire.  She reached 5,367 feet and landed 0.67 miles from the flight line.  I would like to thank Jane Fossen for helping me recover my "Angel of the sky".   As always, thanks Jane!

Angelfire Liftoff

This sequence of images shows the Angelfire liftoff as a series of still photos taken  200 ms apart.  Click on the images at the left, or on the link below, to view them in a larger size.

You can also view this trajectory by downloading the data file at the link below and loading it into Google Earth.  You can then use all the normal  pan, tilt and zoom controls in Google Earth to see it from any angle.  Just right click on the link below, save the file to a convenient place and then open the file from inside the Google Earth program.

This is a short 20 second video that shows a 360 degree "fly around" of the Angelfire flight trajectory. The peak altitude reached by Angelfire was 5,367 feet above the ground.

View video in MPEG2 format    (6.0 MB)

View video in QuickTime format   (6.3 MB)

View video in Windows Media Player format   (1.9 MB)

Click on the charts above to see the altitude and velocity data reported by the GPS.  Each point in the plot represents one GPS reading.  The GPS updates at five times per second, therefore, the readings are spaced apart by 200ms.  The peak altitude was 5,337 feet above the ground.  The peak velocity was 350 mph.  The descent velocity on the main chute was 17mph but then dropped to about 12 mph at lower altitude. (Remember the launch site is already 4500 feet above sea level.) 

The GPS system stayed locked onto the satellites during the whole flight.  However, there is a short 3 second dropout in the data at 145 seconds where I was fiddling with the computer and not pointing the receiver antenna at the rocket!  Data flow resumed immediately as soon as I returned to pointing the antenna properly.

The velocity data plotted above is just the "up" component of velocity.  The GPS also reports the "north" and the "east" components of velocity to give a true 3D velocity vector.   This flight was not perfectly vertical and the plots show that.  The north velocity component peaked at 67 mph and the east component peaked at -48 mph.  (Angelfire went a little to the north west.)  To see plots of all of the GPS data click on the link below. 

Click here to view Angelfire GPS data plots in PDF format

Angelfire also carried an ARTS recording altimeter.  This altimeter uses both an accelerometer and a barometric pressure sensor to collect flight data.  Four pages of analysis of the data from the ARTS altimeter is presented below.  You can click on each page individually to see an image of it, or you can get all four pages at once in a higher resolution PDF document.

  Click here to view Angelfire Flight Data in PDF format

Specific events that can be identified have been highlighted on these plots. 

Maximum acceleration was only 4.0 G's!   Peak velocity was 479 ft/sec (326 mph).  Angelfire reached apogee in 21 seconds.  At apogee the main parachute was accidentally deployed.  The velocity at deployment was extremely low (-6 ft/sec) but there is a very large spike in the acceleration data two seconds later.  The spike is -12.3 G's and has a duration of only 100ms.  I believe that this is the point where the tubular nylon recovery harness ran out of slack and suddenly came tight.  This shock pulse was apparently large enough to break the nosecone shear pins and allow the main chute to tumble out.   The actual main parachute ejection charges were seen going off on schedule as Angelfire descended through the region of 800-1000 feet above ground.

Angelfire uses two MissileWorks altimeters to deploy the drogue and the main parachute.  These two altimeters reported the peak altitude to be 5,529 and 5,591 feet.  As seen above the ARTS altimeter reported the peak altitude as 5,248 feet based on the accelerometer and 5,132 feet based on the pressure sensor.  The GPS reported the peak at 5,337 feet. Averaging all of these altitudes together gives 5,367 feet and all the readings are within +4% to -4% of this value.

Click on each page icon above for a better view.  They show the altitude and velocity data from the GPS and the ARTS plotted on the same charts.  The results overlay pretty well but there are a few minor differences.

  Click here to view flight data comparison plots in PDF format

Yours truly setting up my remote controlled cameras to capture the Starfire liftoff.