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SunGuidance at SEARS Launch March 12, 2005


Boost on D12-0

Staging of D12-5

Locked on sun

Apogee


Flight at the SEARS section's "Space Day" launch. In-flight photographs above courtesy of the SEARS website.

The Sunguidance model was built in 1988 as part of an R&D Project. See the Sunguidance page for more info.

It had last flown in 1999, at the NSL near Huntsville. The servos in it later went bad, so it had not flown since. With the new activity with the Birmingham Rocket Boys, and the Gearcam video camera, I finally got around to fixing it up, replacing the servos with Hitec HS-55's.

The old nose section fins were misplaced, so I made a new set the plug in and are removable for transport). Expecting the model to be a bit more nose heavy, I made the new fins a bit bigger than before.

Some mods were made for the Gearcam to be carried aboard. A 6" long black BT-60 section was added, to give the Gearcam some distance above the nose fines to show their motions in flight. The Gearcam itself was mounted into a piece of Centuri ST-10 tubing, compressed into a square cross-section, and topped with a cut-down vac-formed nose cone. Power for the Gearcam was a 7.4V (2-cell) 145 mAh Lithium-ion battery pack, wired to a 7805 voltage regulator to feed the modified Gearcam the 5 volts it needed. The Lithium-ion pack cut almost exactly one ounce over using a 9 volt battery.


Sunguidance 2005 with Gearcam

Gearcam pod

Photoresistor sensors (nose removed)

A chrome Easter Egg was cut into a 1" curved disc to serve as a convex mirror to show the sun and ground during flight, as was done with three 1988 Cineroc flights.

The model was flown CHAD-staged on D12-0/D12-5 power. There was a LOT of wind at the launch, but that did not affect the model's flight, just how much it drifted. The sun was just about due south, with the wind blowing from west to east at around 20 mph. I didn't angle the model away from the sun as much as I normally would, as the Aerotech Mantis pad's tilt angle was limited and the wind affected the model on the pad. So, it was nearly a straight-up launch which quickly pitched over towards the sun then locked on at about the time it staged.

Once locked on, it wagged quickly back and forth. It was due to the mode being set up for a lot of sensitivity and "hard" maneuvering. It actually turned out to be too much. A mix of the bigger nose fins, maybe a bit more servo motion by the HS-55 servos than the old ones, and the near-parallel photoresistor sensor arrangement. Since the model is carrying video, that's a pretty hard and shaky ride once it locks on, so I'll do something to reduce the sensitivity on future flights.


Shadow shows maneuvering

Locked on sun

Apogee

Ejection

Dual Chutes


After burnout it coasted to apogee, as seen in the middle picture above. Sunguidance models always try to keep the nose pointing at the sun, note that the control fin closest to being parallel to the ground is at max deflection. After apogee, while airspeed is sufficient, it tried to make the model glide a little bit.

Ejection went well, and the chutes deployed. The model drifted a bit but not too far considering. The video signal cut out just before landing, as parked cars were between me (with the hi-gain receiver antenna) and the model as it landed.

There are two versions of the onboard video.

The first is the flight at normal speed, 320 x 230 resolution, 1.7 meg Quicktime Movie.

The second one is the flight at 1/4 speed, 240 x 180 resolution, 1.5 meg Quicktime Movie.

The sound on the 1/4 speed movie is slowed too of course, but also has a bit of a hollow sound that comes from saving it at "web" quality.

On the SEARS website, there is also a 1.2 meg Mpeg movie, shot by a ground-based camcorder.


Apogee horizon rotated in Photoshop

 


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