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Old Jan 27, 2004, 12:41 PM
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United States, TX, McKinney
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Does this sound like a possible DS site?

It's a flood prevention dam that's between 70 and 80 feet high. The surface is small stones of irregular shape averaging about softball size. The slope face is at approximately a 45 degree angle. The top is about 2 standard car widths wide. The backside is identical to the front. When the prevailing west wind kicks up, it hits the face of the dam almost perfectly perpendicular. I sloped the front side this past weekend and I'm guessing the wind was better than 40 mph. There's a nasty rotor right around the lip of the back side. I walked down the back side periodically to get out of the wind and warm up (it was fairly cold). As soon as my head is below the lip it is very calm. The dry weeds that have grown here and there in the rocks were just barely moving even though the front side was getting blasted. What do you think???

If it sounds promising, should I just gain all the altitude I can and then pull the stick back for a loop, dive toward the base of the back side, pull up close to the surface, and see if I can make it back to the rotor?

Thanks, Jim
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Old Jan 27, 2004, 02:19 PM
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Yes, that sounds like a decent DS ridge. Try it in about 15-20mph of wind, and pay attention to where that boundary line is between where the wind is blowing, and not blowing (or even coming up the backside of the dam). You need to get out high or far in front, and then dive as fast as you can for the backside crossing the top of the dam a little above head level (by now you should standing on the back lip). Just before you cross the top of the dam, roll the glider over nearly 90 degrees, and try to keep it on a path parallel to the slope of the backside. Dive deep enough to ensure that the glider is below the level of your feet, and then pull up and bring it back up keeping parallel to the face of the dam and back out the frontside.

Just do that a couple times without trying to go around again. If when you crest the dam from the backside you end up with more altitude than you started with, you know you've got a good DS groove. Don't get greedy. Go around once.. twice.. rest.. make sure your aileron trim is perfect at those speeds so you're not fighting the sticks. Initially it can be easier to make a circle around yourself, but most people settle on a flight path where the glider dives into the backside some distance away, and returns just in front of you so that it's closest to you and coming straight at you, after its passed through the most turbulent air so you can more easily see it to correct for undesirable rolling and such.

ian
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Old Jan 27, 2004, 02:27 PM
Brett
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Adding to what Ian said...pay attention to your elevator trim before you dive in. Carrying a lot of up elevator trim on the front side will tend to make the turn unintentionally as your speed increases on the backside. This often seems to be a contributing factor for newbies turning to tight or too soon off the top. Like Ian said, don't do full circles at first.

If the plane seems a little to eager to circle back down once it gets to the top, add a few clicks of down elevator trim.
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Old Jan 27, 2004, 04:04 PM
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United States, TX, McKinney
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Should I try this with my F-80 or not waste my time (and the plane) trying and get a Moth first?

Tell me if I'm visualizing this correctly.

I get as high and as far out as possible on the front side so as to gain as much airspeed as possible when I turn and fly downwind toward the backside. As I pass the top I should be banked so that I see the top of the plane. I'm almost doing a knife edge now so the plane will start losing altitude as it goes down the back. As soon as I get below the lip pull back on the stick and shoot back out into the lift. Climb and try again.

As I get comfortable and get the plane trimmed for this flight envelope, start going deeper down the backside and doing more circles in an attempt to keep adding speed?

Thanks for the help guys!!
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Old Jan 27, 2004, 04:19 PM
Brett
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That's pretty much it, but just remember, this is not a by-the-numbers thing. Where and when you turn depends greatly on the site and the conditions.

Don't concentrate on making a super hard turn on the bottom either. The idea of getting lots of height before the dive is simply so you have enough energy to climb back out again should you get the turn wrong (once you get good at DS, you can dive into the backside with very little altitude above the ridge).

You don't need to be way far out on the front side to start your dive btw. You can start it from almost directly over the ridge too. Also, rather then just pushing the nose down to dive, some folks prefer to actually enter the pattern as if there were starting a large turn. This might make it easier to get the entry correct. For example, if you were going to do a clockwise DS pattern (as seen by the pilot facing the backside), you might want to start the dive from a right to left pass on the frontside (as seen by the pilot facing the frontside). That's just personal preference though.

One thing is for sure...commit to the dive and the following bottom turn! What I often see is newbies diving down slightly behind the ridge, then leveling off and try to fly level for a bit before pulling up. This just burns your energy. Even worse, they realize their mistake and try and dive down somemore after leveling off. That's a sure ticket to a hike down the hill. Commit to the dive and the turn. The turn does not need to be hard, but it should be smooth and continuous.
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Old Jan 27, 2004, 04:59 PM
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That makes a lot of sense bjaffee! Thanks.

Do you think my MM Glider tech F-80 is up to the task?
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Old Jan 27, 2004, 05:07 PM
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Yep, sounds good. The F80 should be able to pull it off. Might be able to add a little ballast too if you're not getting the energy retention you want. Also consider lowering your aileron rates some if they're currently pretty sensitive.

BTW, for whatever reason I notice more people do counterclockwise turns than clockwise (as viewed from above). Do it whichever way you're most comfortable, and for whatever reason there is usually a comfortable direction and an uncomfortable direction (at least until you get real good). It has to do with which way you reflexively react to turbulence the quickest. I find that I'm quicker to roll out to the right if I get in trouble so my turns are counter clockwise.

Brett's advice is good about flying a crossing pattern before the turn. For me, for instance, I might start up high and to the right on the front side, dive down across the front of the dam right to left, level out as it goes past me, wait a second, and then roll over to the left and make what amounts to a 270 degree turn over the backside and straight back out the front.

Here's a video of me exploring a new DS groove for the very first time with the ballasted M60.
http://www.houseofthud.com/videos/mtzionNW-DS2.avi
Not super exciting stuff, but you can see I use the exact progression that I described to you above. In and out once.. then again... then again, maybe around a couple times, then several times. I really enjoy moving between the front and backside, so I often punch out to the front to play and I like a good zoom. I was also making really really big loops to see how far down the rotor reached. So far the wind hasn't been right to get up there again, but I keep looking forward to it.

ian
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Old Jan 27, 2004, 07:06 PM
Brett
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With regards to the F-80...I'd say maybe, or maybe not. I don't think it will be easy to do with that plane. I remember trying to DS my DAW P-51 and it was a bit challenging. The plane just wouldn't hold energy long enough to make smooth, consistant circles. It's still worth a try though, and the experience will be helpful even if it doesn't really work.
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Old Jan 28, 2004, 03:45 PM
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Sweeeet! Great video!

Is that a 48" Moth?
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Old Jan 28, 2004, 05:00 PM
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It's an M60 with a pound of ballast. I say it wasn't super exciting on the backside in that video, because by comparison the frontside flying that day was totally off the hook.
http://www.houseofthud.com/videos/mt...w-music2-4.avi
http://www.houseofthud.com/videos/mt...usic1-divx.avi

In the same conditions, if I focused on the dynamic soaring, I'm sure I could get it seriously rocking.
At the time I was DSing in the video, I hadn't yet figured out how/where I was going to land, having never flown the cliff side of the ridge before.

ian
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