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Are we using the wrong "shaped" Ds hills ?

Started by cambrad, June 03, 2013, 13:30:31 pm

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cambrad

Just been watching a vid of the new JW mouldie on you tube at Weldon and made me think. Are we using the wrong shaped ds hills? Every time i watch a vid filmed at Weldon i cant get my head around how that hill produces such amazing speeds. As far as i understand the requirements of a ds hill, basically you need a hill with a longish UNBROKEN ridge that also drops of quite sharply at both sides??? Whenever you look at weldon the ridge appears to dip sharply in the middle, the plane looks to enter the backside through the "gap" in the ridge and return up the shielded backside and through the shear layer. How can this work so well.
Vid below of the jw for view of the hill.

Chip Hyde flying the molded JW60 at Weldon - California

Cactus

you'd thought the wind would come through the gap and make a right mess of the backside

pun intended
I know you believe you understand what you think i said, but i am not sure you realise that what you think you heard is not what i meant.

deckit

Have noted the apparent 'gap' at Weldon on many videos, but I recall from examining the contours a while back there is no break in way in the ridge.

It's well-established that the windward side need not be steep; just needs to produce a workable shear over the back.
And of course enough lift to get airborne unless done by artificial means.

wdeighton

we do have a variety in the UK

Re can vary

Black hill is like the roof on a swis house. (Not good for landing)

Skirrid can also vary

the widest one I have flown was sea horse. It was a bit turbulent that day so I didn't do much more than 2 to 3 exploratory laps and than just thought is wasn't worth it. Would love to get back up and try again.

HH as a very very slow rising front size. Only just enough to get up, but then falls away vertical.

Even the lads that have been dsing these hills for years are still learning about the way the hill behaves with different strengths, different directions and the different lines you have to fly due to the shape.

AvB

June 13, 2013, 03:24:01 am #4 Last Edit: June 13, 2013, 03:26:56 am by AvB
Interesting point. Weldon does have a big dip/ saddle, and you do drop in right over it ... or over the end of the high section as it drops down to the saddle. Larrikin Ridge here in Oz is longish, and the best line is standing on a hill on the ridge and dropping in over a big saddle. At Bird Springs Pass you drop in over a shallow saddle but you wouldn't call it a gap. Cactus Ridge over here, our fastest site, does not have a deep dip. Norco doesn't have a dip either. Tekapo in NZ, where Alex got 456, is long and no dip. Same for Wainui and Camerons Track in NZ which are big 300+ sites ... they are long ridges with no major dip in the drop-in area, and they have absolutely beautiful clean shear.  I think it really varies with every hill and the angle of the wind to the hill. It always comes down to keeping on trying different spots and lines.