|Mar 23, 2010, 10:54 AM|
SVSS 3/20-21 Davis XC contest report
SVSS Davis March 20-21 XC event - Day 1 - Distance task
If it was easy it would'nt be called fishing, it would be called catching. Or something like that. Which pretty much sums up saturday's distance task. Cooler temperatures, a general hazy grey cloud cover and southwest breeze promised for a tough day. We had a good turnout with 10 teams showing up from across California from LA all the way up to Oregon. The pilots meeting kicked off at 10am and the new distance course was laid out. There are three main XC venues in California held each year at Montague, Davis and Cal Valley with Davis being different from the other two in that we are using a proscribed course with the order of the course turnpoints and direction set. At 26 miles our distance course is also the shortest. I really like the variety of these three different XC locations. Montague is king of the hill with a beautiful course in the Shasta Valley up near the California/Oregon border. Cal valley is in a desolate area of the coastal foothills of south central California about 40 miles east of Santa Maria. It's course is laid out over high desert tumbleweed terrain surrounding a dry soda lakebed and is known for it's scary monster thermals. Davis is absolutely flat ag land with straight roads, crops and orchards, a patchwork of brown and green. All three are challenging in their own way and we left coast fliers are lucky to have this variety.
For this year Dudley Dufort offered me the chance to co-CD the event and I gladly accepted so I drove around and spent a little time laying out a new course to try and avoid the dirt roads we've had problems with in the past. Dirt roads can be hazardous to your XC racers' health when you are specked out cruising along and dust from a vehicle in front of you suddenly renders your sailplane invisible. Its surprising how a small amount of dust in the air can cause this problem. The entire 26 mile Davis course is paved except for a few hundred yards of gravel road just before TP8. Thats about the best we could do without doubling back on any previously traveled part of the route. We also decided that there would be no time limit for Distance. Winches would be shut down at 3pm and as long as you were in the air at 3pm you could fly as long as possible. No limit on flying time could potentially lead to flights in the category of "epic".
By noon on Saturday no teams had managed to get out on course and it was starting to look pretty grim. Much hand wringing, wailing and gnashing of teeth ensued. A halo formed around the blurred out sun and the amateur weathermen amoung our ranks confidently predicted rain to add to our misery. One thing I do notice when things occasionally get bleak during these XC adventures is it really brings out the "glass is half full/half empty" aspects of the various personalities. Maybe someday I'll be able to join the ranks of the "glass half full" strong silent types but on this particular day I was doing my fair share of moaning along with the rest of our sorry lot. After repeated launches and what felt like hours of listening to the dreaded buzz of dead air from our vario my teammate Bill and I got so frustrated we decided to hell with it, we're heading out no matter what so we grounded our racer and launched Bill's Ava Pro, piled into the truck and moved out. All of 0.6 miles. Still, it was miles on the scoresheet and we were now officially in first place. That was the first time I've flown XC with a TD ship and no vario. The Ava is a fine floater and can penetrate wind even with such a light wing loading but right off I could see a problem. It is hard to visually read lift from a moving vehicle so knowing when to stop and thermal can be a problem. I think for effective XC flying a vario is more than just a luxury, its a necessity. Our second attempt with me at the controls resulted in zero miles and our third attempt with Bill piloting got us 1.2 miles down the course. By then it was 1pm and lift was starting to break loose so we launched our racer, found a decent but fast moving thermal on the south end of the field and managed about 450 meters before making the dash thru the Eucalyptus tree tunnel at the field entrance and went for it. Once off the field things seemed to improve and we found weak widely spaced thermals to about 400-500 meters, enough to keep us moving west flying crosswind in the south wind. Rounding TP1 things changed and we were now flying into a south headwind quartering from the west. Headwind flying in XC is challenging but Dudley proved at last fall's Cal Valley event that patience and persistance can win the day so we kept chasing thermals downwind slowly netting distance in the process in a sort of ratcheting stairstepping fashion. Proceeding in this way at about 5-10mph ground speed it seemed to take forever. Headwind flying like this can be hard on the nerves. Rounding TP2 we suddenly had a tail wind as the wind was more westerly now and at 50mph we barely managed to get in front of our racer over the 1 mile between TP2 and TP3. After TP3 it was more of the same hard slog into the wind but suddenly it became warm and the wind died a little, the sun shown a little brighter and a large lift cycle boosted us to 600 meters and raised our hopes we could make it to the old Mill at TP6 at the most southerly part of the course and ride a tail wind most of the way home. But, not to be and things cooled down and the wind came back with a vengeance feeding into the large lift cycle we left behind. Nearing TP4 with our plane only 30ft above our heads directly over the road I briefly considered trying to slope soar it off the large plexiglas windscreen mounted above the cab of my truck but the large turbulence set off by our vehicle tossed the racer up on a wing tip and nixed that stupid idea. After nearly 2 hours of flying we landed a few yards short of TP4 for a total of 10.5 (brutal) miles. John Ellias made it to TP6 but ran out of lift and landed there with a total of 13.8 miles for the win. 7 of the 10 teams made it off field and onto the course. It was a tough day.
Day 1 - Distance:
1st Screaming Eagles 13.7 miles, 1000 points (John and Marquita Ellias) MXC
2nd Windward 10.5 miles, 761 points (Steve Henke, Bill Curry, Mike Clancy) Norsworthy Racer #3
3rd Green Team 5. 6 miles, 406 points ( Jim Thomas, Frank Schlosser) SagittaXC (can you believe it?)
Day 2 - Speed Task
I'm sure I'm not the only pilot who went home Saturday evening and prayed to the weather gods. But to no avail. When I arrived at the field Sunday morning it was winter cold, same grey sky, same halo around a veiled sun, same chorus of moaning from the "half-empty" contingent, same 5-10 southerly wind but now with a line of clouds in the distance. We of the half-empty clan were thinking rain and after saturday's events not hopeful for a good ending to the weekend. March is such a crapshoot for an XC event. But clouds with the instability they bring can also mean the dead flat conditions can get broken up.
Today was Speed task on a proscribed 16 mile loop (see attached course map). As a change from previous years we decided to do a remote start and finish. This is because a finish line at our field is somewhat hazardous with large trees and difficult parking. For this new speed course pilots would need to winch launch, get off the field and fly 1.5 miles to the starting gate. This was not as bad as it seemed as conditions between the field and start were consistently better than on the field itself and there are good opportunities to tank up between the field and start. Also, having the remote start and finish at the same corner on the 16 mile loop I hoped it would be possible to cross the finish at speed, zoom up, find another thermal to tank up then head back out on course for a second attempt without having to land, get back to the field and winch launch again. A lot of time can be saved and it may even be possible to get three attempts on a single flight in the right conditions. As it turns out the winning team did just this to thier advantage in getting the win completing two laps of the course.
Like Saturday conditions were slow to develop and it was 1 pm before teams started finding enough lift on the field to make an attempt. We decided to move the cutoff time from 3pm to 4pm due to the late start which turned out to be a good move. It also was starting to warm up and the wind was dying down. What in the morning had seemed hopeless was now looking much better. Seven teams made it off the field and onto the course. My team (Windward) got off field about 1:30 and made it to the remote start but we ran out of luck at about a mile further and landed out. On our second attempt we arrived at the start just as John Ellias' team (Screaming Eagles) arrived at the finish so I knew conditions had improved dramatically. The clouds had brought instability, there was blue sky, the wind had died and all were happy. I guess miracles do happen and I dont remember ever seeing such a dramatic change in weather over such a short time span at our field. From winter to spring in just a few hours.
Ellias had left before our first attempt so I knew it had been a long flight. Sure enough, he searched, found a thermal, then joined our thermal for a time, then headed back to the start to re-start his clock for his second attempt (smart move) . Then Rich Spicer's team (Atomic Fireball) crossed the finish so the race was on. Rich landed so I figured he must have had a pretty good lap time. In speed with the FAI scoring we use, once you have one lap in the bag you can go all out on the second one knowing you wont get killed in the scoring. If any team finishes the course the rest of the teams must finish or take a heavy score penalty. The finishing team with the fastest time is awarded 1000 points. Remaining teams that finish are scored using the formula 700 + (winning team time/team time X 300). If a winning team completed the course in one hour and another team completed it in 10 hours the worst the slower team could score would still be over 700 points. Meanwhile teams that dont finish are scored using the formula (distance flown/course distance X 700). The best a team that does not finish the course can score is still under 700 points. This is a good system as it narrows the point spread between slow teams and fast teams (think MXC vs. SagittaXC).
One highlight of our second flight was when we flew into a thermal occupied by a pair of red tail hawks. With one hawk above our plane and one below it soon became apparent these were a mating pair when the male, flying top cover, repeatedly dive bombed us (dont worry Greg, no talon holes in good ole #3). Unfortunately my team fizzled out again about a mile past TP1. Ellias blasted by us as we were packing up on his way to the win. Four teams finished the course which pretty much ended my team's chance for a top three overall trophy. Ellias finished it twice with a 53 minute fast lap time to take the win. He even landed back on the field, another masterful display of flying skill. Thermals were stronger in the nice conditions with teams reporting hieghts of 700-800 meters. All in all a very nice finish to a challenging weekend.
Day 2 - Speed:
1st Screaming Eagles 53 minutes, 1000 points (John and Marquita Ellias) MXC
2nd Flying Tigers 62 minutes, 956 points (Dean Gradwell, Ron McElliot, Roger Hebner) MXC
3rd Atomic Fireball 64 minutes, 948 points ( Rich Spicer, Kent Kollings) MXC
Two Day overall Score:
1st Screaming Eagles 2000 points (John and Marquita Ellias) MXC
2nd Flying Tigers 1232 points (Dean Gradwell, Ron McElliot, Roger Hebner) MXC
3rd Atomic Fireball 948 points ( Rich Spicer, Kent Kollings) MXC
MXC dominates again...
I had planned to take more pictures and video but didnt manage much. The video on the youtube link below was taken on day 2. I would also like to thank Mike Clancy for doing a great job as driver and Greg Norsworthy for his continued loan of trusty #3, team Windward would not exist right now without it. She aint purty but she sure flies well.
some notes and observations:
I've been flying XC for over 10 years now but have never been involved with running an event and (like most people) would much prefer to kick back as a participant. But there are a few ideas I wanted to try for our Davis contest and Dudley let me run with it.
Plastic laminating the maps back to back worked out well and makes it easier for drivers as they fumble around for papers, pens, stop watches, trip odometers, etc. I forgot to tell the teams at the pilots meeting that I wanted them back so we could re-use them but by sunday afternoon figured what the hell, keep em. Use them for placemats if you like. Come to more Davis events and you can end up with a whole set!
The flourescent orange TP markers worked out well. Using two of them (one with a number and one with an arrow) made them very visible. No team complained of not seeing TP markers.
The scoresheets need some work. Also I think putting both distance and speed on one sheet front and back might be better.
providing clipboards to all teams also made things a little easier for the drivers. thats a keeper.
I didnt do so well at spelling out the info at the pilots meeting. I think writing it all down on paper and providing the teams with a handout would help.
GPS.... I think most of the teams now have GPS. GPS is the future of XC and adds a whole new dimension. I just love playing around with the flight plots on Google Earth. One side effect of GPS however.... its pretty tough to stick to the tall tales and fish stories when the facts are staring you in the face. I typed this report up before viewing my distance flight and had to laugh as I "re-edited" a few minor errors in my report to make reality jibe with memory.
See you at the Soaring Safari!! wonder what course Dudley has for us this time....
|Mar 23, 2010, 02:08 PM|
|Mar 24, 2010, 02:22 PM|
the unit is nice and small and a lot of fun to play around with. The 70 ma draw is not a problem with the big batteries we carry in XC ships.
I know Dean Gradwell is moving in the direction of GPS scoring at Montague (like full scale racing). I think over time the plots will also become useful in identifying reliable thermal generators. Most of the experienced pilots know of fairly reliable generators on the various courses, also the areas that are likely to create sink conditions, but there is potential for these GPS units to identify even more generators. For Davis this last weekend on my teams flights I noticed we hit a decent thermal over this farm complex both saturday and sunday. I also saw two other teams find it here. The attached pic is looking straight down. The thermal was being carried north by the wind. you can bet I'll remember this location during future races.
|Mar 24, 2010, 02:49 PM|
another vertical shot at TP2 and TP3 showing thermals being blown to the northeast. The one on the left is possibly coming off the farm building complex below it (another possible generator to consider for the future). Also notice how I cant seem to fly a straight line between thermals and you can see from the ground shadow trace how badly I missjudged rounding the corners. Thats a lot of wasted energy that might have made a difference in the sink cycle that killed my flight. I need to think about this. Heading hold gyro on rudder?? The chase vehicle and sailplane are at the turnpoints at the same time. Maybe some sort of sighting device showing the pilot and or spotter where straight up is in the sky at the TP to guide the sailplane better for a more accurate rounding of the TP? I'll bet errors like this over the course of a 30+ mile flight could add up to miles of wasted potential energy not to mention many minutes of flight time.
|Mar 24, 2010, 03:52 PM|
I've got a working prototype that sends back live data. It's NMEA format and works with most map programs. You could watch the flight live on your laptop.
|Mar 24, 2010, 09:36 PM|
|Mar 24, 2010, 11:39 PM|
Joined Sep 2006
Thanks TB it looks like it has Bubble Dancer ancestry. Is it just me or does it look like it has a shorter chord and a longer wingspan than the other XC's in the vid?
|Mar 25, 2010, 11:29 AM|
I copied the data below from the XCBD thread. Notice that the most dominate design, the MXC, also has the lowest aspect ratio. Very visible with its 14" chord, very fast and seems to thermal quite well. I was sorely tempted to buy one that Dean Gradwell had for sale last weekend at our event. I am not sold on the high AR advantage because of the success of the MXC over the last few years. I dont have much experience with them, only about a half hour of stick time but talking with MXC pilots they all praise it's handling and overall performance. Dean described it to me as the closest thing to full scale in the way it feels that he's flown.
XCBD (per Drela plans):
area = 1330 sq in
span = 157 in
root chord = 10.5"
AR = 18.5
AUW = 88 oz (per Anker)
wing loading = 9.5 oz/sq ft (19.0 oz/sq ft @ 11lb)
large XCBD (scaled Drela plans):
area = 1738 sq in
span = 179 in
root chord = 12"
AR = 18.5
AUW = 131 oz (projected)
wing loading = 10.9 oz/sq ft (14.6 oz/sq ft @ 11lb)
area = 1719 sq in
span = 157 in
root chord = 14"
AR = 14.9
AUW = 109 oz (projected)
wing loading = 9.13 oz/sq ft (14.7 oz/sq ft @ 11lb)
area = 1545 sq in
span = 170 in
root chord = 12"
AR = 18.7
AUW = 176 oz
wing loading = 16.4 oz/sq ft @ 11lb
area = 1718 sq in
span = 156 in
root chord = 14"
AR = 14.2
AUW = 176 oz
wing loading = 14.8 oz/sq ft @ 11lb
Ascendant XC (Anker):
area = 2325 sq in
span = 187.75 in
root chord = 14"
AR = 15.2
AUW = 152 oz (projected)
wing loading = 9.4 oz/sq ft (10.9 oz/sq ft @ 11lb)
Stalker 3.9 (Daryl Perkins):
area = 1325 sq in
span = 153.5 in
root chord = 10.52"
AR = 17.8
AUW = 75-80 oz
wing loading = 8.17-8.70 oz/sq ft
|Mar 26, 2010, 10:00 PM|
Everything becomes a compromise centered on the 5kg max weight, wide chord for visibility, high wing loading for speed and wind penetration, etc. Most pilots would probably agree that these limitations result in optimum designs at around 160"-170" wing span, 5kg weight, 15+ oz loading, 12"-14" root chord, 14-18 aspect ratio.
|Mar 27, 2010, 12:35 AM|
Joined Sep 2006
Huh, so its more of a compromise of visibility vs. performance, Is there any rhyme or reason to having the bubble dance tail? it seems more vulnerable to damage.
|Mar 27, 2010, 12:35 PM|
back to the farm thermal, here I attempted to look down "thru the tube" by getting above it looking down from the north. The farm buildings are all metal roofed and surrounded on all sides by orchards. Looking down thru the thermal as best I can its obvious the source is the farm building complex. A pretty reliable fixed structure generator as opposed to the many thermals kicked off in the plowed fields that can come randomly from just about anywhere.
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