Field Day Flying
write-up by Daniel Marsh dmarsh@speakeasy.org
Field Day Intro
SWN Field Day 2003 was a wonderful event that had many aspects to it. Some of the chief projects included a routed link from Magnolia across Elliot Bay to Alki and then back across the water again to a high bandwidth internet link midway up the Columbia Tower in downtown Seattle. One sub-event in which I participated was a joint flyover by a Beachcraft Bonanza airplane and a Robson R22 helicopter. The flyover had many goals, including:
- The establishment of an air to air link
- Air to ground link
- Taking pictures to give people outside of Seattle a sense of the challenges of Field Day
- Aerial survey of observed access points.
Prior to Takeoff
Most of the prep work for the flyover occured over email, with one short meeting with the airplane pilot the night before field day. As such, we had our work cut out for us the morning of the flyover. The biggest concern was in securing antennas to the vehicles in such a way that they wouldn't cause damage even if they were to fly off. We ended up using a 5 db mag-mount omni antenna as somewhat of a compromise solution. We would have liked to mount a panel antenna, but didn't have the time or tools to do it right. It was very difficult to find a place to mount an antenna on the under side of fuselage that would both give us enough cable to feed into the cabin and also not risk vital components if something fell off. The omni antenna mounted to the underside of the foot step fit the bill admirably. Between the magnetic mount and half a roll of electrical tape, the antenna was able to withstand the 185 MPH speeds nicely. Here are some pictures of the plane's jury-rigged antenna.
We also tested communications between our notebooks and our power set-up to ensure smooth operation in the air. The airplane was able to provide an isolated DC power circuit to a DC/AC invertor feeding a multi outlet power strip to suppy our laptops and sundry other devices during the flight. The helicopter couldn't provide power, so we rigged a battery box and an invertor together to supply power during the flight. Unfortunately, the helicopter's cabin was too small and the battery box too heavy that it had to be abandoned for safety concerns shortly before takeoff. As it was, trying to juggle all the equipment in the helicopter was difficult, at best. Here is what Dave (the helicopter's passenger) had to say about the experience:
Patrick was an excellent pilot - he did a great job of prepping me for what to expect and was very clear about what the potential safety hazards might be. First and foremost was that anything loose in the cockpit would probably go out the door at some point and shatter the tail rotor, causing the helicopter to spin out of the sky. I took him at his word and made sure that the extra headset was clamped firmly around my thigh, the antenna was clutched between my toes and the laptop was held with two hands at all times. This worked against me when I had to tune the handheld or re-orient the camera as I had to lean forward and still keep a firm grip on the laptop. In the end, we returned with everything we left with, so it all worked out. The laptop screen size was too big to manage safely with the controls so close to my knees. The large size was nice, but a PDA with a bright screen would have worked better from a size/visibility standpoint. The laptop screen was almost illegible in the direct sunlight, requiring me to put my face right up to the screen to read anything. Having so many cords dangling from the laptop didn't help either - an external power cord would probably have made it worse.
Takeoff
The plane went "wheels up" at around 11:15 and the helicopter lifted off a little after noon. Because the plane tookoff first, we had around an hour before our scheduled rendezvous with the helicopter over the Alki site. We used this time to fly over mercer island to the eastside and then head north and finally east over magnolia. All throughout this time, the notebook hooked to the external antenna was running netstumbler. During takeoff and initial ascent, we were logging as many as 5-6 AP's a second, but this rate fell off sharply once we reached our 3-5 thousand foot cruising altitude. Given that netstumbler needs to be able to get data to the AP in order to retrieve information, a passive stumbler like Kismet may yield much better results. We would like to try Kismet with a panel antenna sometime in the future for comparison. As is, we logged over 1000 AP's during our flight. Here is a copy of the stumble:
http://seattlewireless.net/misc/war_flying.zip
Cruising
Once we were finished with our free flight over the eastside, Erik (our pilot) smooth talked the air traffic controllers into letting us circle Elliot Bay at between 4 and 5 thousand feet. As I gathered later, this is a somewhat unusual request, as it is in the middle of a commercial jet pattern. In fact, we heard the controllers directing airliners to stay away from us. Way to go Erik! Our somewhat oblong path had us circling between Alki and Seattle Center (where we could see the crowds of bumbershoot) maybe half a dozen times. Here are some pictures from cruising that show some of the field day sites.
I believe the 3rd picture shows both the Alki and Magnolia sites and should give you an idea of the distance of the link, but I wasn't quite sure where to put my cirlce on Magnolia. If someone can pinpoint the site for me, please send me an email.
After looping around Alki a number of times and failing to contact the helicopter on FRS radio, we headed north to kill time. We finally did make contact with the helicopter and returned to Alki to attempt our air to air 802.11b link. Unfortunately, space in the bubble of the copter was so restricted and there were weight concerns, that the battery box was left behind. We got back to Alki, only to learn that the laptop was out of power. This was disappointing to us, as we had planned a number of demo applications to demonstrate the link, including streaming MP3's, web serving and a short game of Quake. I guess Quake will have to wait till next time.
Landing and Wrapup
By this point in the trip, we had accomplished all that we could for this first attempt, so decided to pack it in and head for Boeing field. Thanks to Erik for the smooth flight and landing. We all had a great time doing the flyover and there seems to be some interest in doing it again in the future.
Acknowledgements to all who participated in the flyover, namely:
- Patrick Cordell - Helicopter pilot
- Dave Carey - Helicopter Passenger
- Erik Utter - Plane Pilot
- Colin Pyle - Passenger
- Daniel Marsh(myself) - Passenger
- Karl Kulaga - Passenger all the way from Portland's Personal Telco!
Errata
We have at least 4 galleries of pictures and movies that will be posted here once hosting has been arranged.
Karl's Gallery - ["http://students.washington.edu/dejann/karl/']
