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        Discussion First Dynamic Soaring Attempts at A Small Dam

#1 barryplem Nov 13, 2012 09:41 PM

First Dynamic Soaring Attempts at A Small Dam
Hi Everyone,

I'm a regular DLG flyer, and frequent the handlaunch forums. Recently, cold fronts have been bringing Northwest winds in my area (Raleigh, NC), and I've been getting a bit of a "slope bug;" bringing my DLG's to the dams in the local area and sloping/thermalling. On some stronger days, I've tried DS'ing the backside of the dam (generally the steeper part, opposite of the lake and the grassy side), to very marginal success. I've gotten up to 5 circuits now, in maybe a 15kt wind, but am having trouble topping that. So here's my questions:

Are the conditions/site that I'm attempting this in (and model, mind you) feasible to DS, even for an experienced DSer? It seems I gain energy as I come back through the shear layer( or whatever it's called :o ) and turn downwind, but I drift down wind with my circles or "peter out" on my way back up wind.

Should I try adding some more ballast, maybe? I'm flying a Helios, a Zone V2 molded DLG and have tried 10.2 (unballasted), 11.2, and 12.2 ounces. The plane can rip pretty good at that weight, but it doesn't seem to improve its abilities much. It's a thin foil, too.

Will more wind speed help? 15-20 mph is about as much as we'll get here, but just curious on this point.

Anyway, I know what I'm describing would almost have to be seen in person to offer suggestions, but since I'm about the only person I know trying to do this on the East coast, I thought I'd try this and forge on solo. Thanks in advance for any advice or pointers.


P.s. For coming back up wind (in the calm-ish air), I'm flying quite low. As in, if the answer to my question is "you should be lower coming upwind", my skills won't allow it ;)

#2 barryplem Nov 13, 2012 09:42 PM

EDIT: The only person I know trying to do this near me, don't want to step on any toes ;)

#3 ALEX HEWSON Nov 13, 2012 10:26 PM

There is video somewhere of me DSing my Stobel V3 at Weldon.

Key is a clean shear (nice even sharp ridge) and you don't need much wind. I was flying in about 10kts

More weight will help with energy

Make sure you always cross the shear line.

Also smaller circuits work best with the DLGs. Say 20ft dia.

#4 barryplem Nov 13, 2012 10:40 PM

Hi Alex,

Thank you for your advice. I've actually seen that video a couple of times. I have a Stobel V3 as well, but haven't tried DSing it, though the Helios is just as slippery. I'm afraid the shear line may be the issue; I don't think the angle is acute enough to make a sharp shear. I am going to try a tighter circle, as mine are quite a bit bigger than that I believe.


#5 ALEX HEWSON Nov 13, 2012 11:23 PM

Key is finding just the right sized orbit. DLGs are tricky to DS because of this and their light weight

#6 jonoashton Nov 13, 2012 11:34 PM

I am a beginner as well but I have found that if there is wind on the back of the slope (from any direction), it is hard or impossible to DS. If it is pretty much dead calm on the back, it always appears to work. I have DS’ed thermal gliders in light wind before but do not own a DLG so can’t comment there.


#7 sll914 Nov 14, 2012 12:50 AM

Hi Barry,

I'm a former East Coast DSer and have plenty of experience DSing dams with anything from DLGs to wings, JWs, etc... I agree with Alex that you probably need to tighten up to a smaller circuit and use whatever ballast you can fit. Be careful when you get going faster though since DLGs don't have much of a spar to take the bending loads.

Ideally, I'd recommend getting a JW from www.L2airframes.com and build it out light like 30-40oz. It will do what you want it to in 10-20knt winds, and will take a bit of a beating and keep on flying. A DLG is a tough intro to DS but once you've got the hang of it, they can be alot of fun in light winds.


Also, make sure the wind is square to the dam so that the backside is calm...

#8 Sleedo Nov 14, 2012 05:44 AM

Although you stepped on my toes :D I figured I would chime in as a fellow East Coast DSer. I have been DSing for a few years now on Cape Cod, the conditions have been very light and the backside very shallow. Really would be considered topside DS slopes. My experience has been that DLGs make poor DSers, although they can be fast when ballasted I think that the thin foils are not efficient when pulling Gs at speed. A wing like a Bee is a great intro DS plane, mine is going strong after years and countless high speed crashes. They were designed to take abuse and pull hard turns. I recently built a NCFM Moth, kinda heavy, covered in 10mil New Stuff and flew it at the Cape a few weeks ago. You can see in the video below that it really locks into a turn and is very stable. Best thing is that I have no fear getting low enough to take full advantage of the shear (look for the wing drag near the beginning of the video). Skip to about 3minutes in to see the fastest laps ever witnessed on Cape Cod (hope I'm not stepping on any toes! ;-) ).
Sleedo ds groove (3 min 56 sec)

#9 SpeedsterDEN Nov 14, 2012 11:42 AM

My advise:
Just go low and be sure that you are down in the lee area, and low again over the top, specialy with light models and small size DS site.
Give it ballast, then there is much more energy to go over the top again.
My small DS dunes, (up to 60 feet high) are only good for DS flying in up to 22 knots wind and wind almost tight on the slope.
More wind than this, give a very small and turbolent lee area where there is no chance to control the glider.
Dont ask how i know,,, :D

My video for DS beginners :)
DS for beginners. (1 min 50 sec)

Ds at a very small dune with my scratch build Mega wisel.
Specialy here its important to go very low to get under the wind and to keep the energy, just one bad lap and you are toast.
Mega Wiesel, mini DS. (1 min 27 sec)

How heigh is your dam ?

Good luck

#10 gizzo Nov 14, 2012 03:45 PM

All that good advice. I've been having fun dsing an art hobby bobolink 1m dlg behind a dune at the beach, about 15' high on the back, maybe 25' on front.its really fun in a slow way in about 5kt.good luck man.

#11 SpeedsterDEN Nov 14, 2012 04:13 PM


Originally Posted by gizzo (Post 23268908)
All that good advice. I've been having fun dsing an art hobby bobolink 1m dlg behind a dune at the beach, about 15' high on the back, maybe 25' on front.its really fun in a slow way in about 5kt.good luck man.

Cool, yes not much slope is needed if the top is sharp.
This give a realy small boundary layer where you realy can hear the air speed change, like this:
(Site view at 1:25 in video.)
The sound of speed, Dsing my Destiny. (1 min 41 sec)

Same site, less wind with 3,2 meter F3b
Trinitus Dsing. (1 min 0 sec)

Dynamic soaring. High speed Boundary layer passes. (0 min 30 sec)

Tree line DS, Dynamic soaring. (1 min 43 sec)

Not risk no fun :):
Wiesel light, Sloping and DS (2 min 14 sec)


#12 Aerogance Nov 14, 2012 07:15 PM

That last video really sums up the desperation to DS that we experience! Cheers!

#13 sll914 Nov 15, 2012 11:22 AM

Nice flying on that last one Speedster. That was cool!

#14 Daemon Nov 15, 2012 12:18 PM

For whatever it's worth, I started out DSing on an earthen dam, and I remember it
turned out to be one of the hardest places to DS. The faces were just
shallow enough that the shear layer was usually very low so always had to dig deep
(without hitting the flatter area below the dam). I remember it was extremely
sensitive to wind speed. Too little wind, and couldn't get enough energy to keep
the loops going. Too much wind and it just blew out completely flat and couldn't
get below the shear. It had a sweet spot around 15mph which produced the best
frontside lift, and the best groove and thermals would really pump it up, but they
were rare, since the upwind side was the lake. Because the shear was
so low and flat, rarely had to bother crossing the top of the dam to the front
(whole circuit was behind the top).

Like any other groove, if I stood on the back edge of the flat top, the
best indicator of whether the groove would work or not was where
the wind was hitting my body. If I could feel it on my legs, it was blown out.
Chest only, workable. Quiet, pumped up.


#15 SpeedsterDEN Nov 15, 2012 02:06 PM

This video started my Ds adventures :).

Dynamic Soaring (DS) on 50ft Dam in Tennessee... (onboard video) (7 min 12 sec)

I could see that Ds was possibly in light wind and on a very small ridge, an the dam was looking almost as the small dunes in my area.
No other persons was Dsing here so it was learning the hard way,
Internet, Youtube, flying, crashing, building, youtube, flying, cras...., ...

More small DS
Not world record, but extreme any way :)

Alula DS. (Do not try this at home) (2 min 33 sec)


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