Weight shift and thermal technique

Past, present, and future flights, meeting times & places, theory.

Moderator: Moderation Team

Weight shift and thermal technique

Postby Simon » Wed Nov 19, 2008 8:54 am

I am mostly writing this to solidify my own understanding of paragliding, and for others to criticize as they please. So to start, here's a sketch did in Illustrator.

wing profile.jpg


From what I have deduced, added weight to one side of the wing alters the profile of that half of the wing. This creates more drag for that side of the wing, without changing the angle of attack, while the other wing counter-actively becomes more aerodynamic and accelerates faster than the loaded wing. The sketch is an exaggeration of a wing profile and a loaded wing profile.

Now here is my thermal technique

thermal technique.jpg


This is exaggerated as well and will always change with the weather. It's an illustration of me entering a thermal, finding the high pressure system at the edge of the thermal, doing two 180 degree turns in the core, then dragging out my upwind leg as much as possible. On the upwind leg I increase brake pressure to a little less than minimum sink and gently shift my body side to side. I have always been told to use linked 360's, but haven't been one to abide by that.

See you all at the League meet on Sunday.
User avatar
Simon
 
Posts: 73
Joined: Tue Jun 17, 2008 8:16 am

Re: Weight shift and thermal technique

Postby Leeside » Wed Nov 19, 2008 11:08 pm

So how was your flight?
Last edited by Leeside on Thu Nov 20, 2008 12:23 pm, edited 1 time in total.
Hangliding is not the best.
Paragliding is not the best.
Thermal flying IS the best!
Leeside
 
Posts: 54
Joined: Wed Feb 14, 2007 10:00 am
Location: INADAIR

Re: Weight shift and thermal technique

Postby Simon » Thu Nov 20, 2008 5:00 am

Fair question to ask. Here it is,

Took a flight this weekend in Ojai and it was great. This was my second Ojai flight, and I was joined by Mark P (Nitrous), Mark M (Treeman), and Fast Eddie (thank you for being there to retrieve and for the flying tips). Wind was blowing East at 6 gusting to 10, so we launched at Nordhoff Peak. I was the first to launch even though I failed my first attempt. Worked my way out to Front Point, but wasn't taking Eddie's advice and was flying too low and too far from the ridge. (Personally I don't mind using ridge lift and scratching the hell out of Oat Mt because I've watched Nitrous do it multiple times, but i hesitate to do it anywhere else, especially on an East wind day.) I ended up flying out to Bruces, and in the process climbing to 5685'. I stayed there as long as I could waiting for my Sensei, Nitrous, to come out and join Treeman and myself. Unfortunately he did not launch, so Mark and I soared for as long as we could. We stayed above and around Front Point for a while and had our sites set on Nordhoff High School as our LZ, but lacked the altitude and were facing a headwind. We landed on the southside base of some small hills south of the base of Pyramid.

flight time: 0:53:48, max alt: 5685', ascent: 920 ft/min, descent: 950 ft/min
Last edited by Simon on Mon Nov 24, 2008 7:34 am, edited 1 time in total.
User avatar
Simon
 
Posts: 73
Joined: Tue Jun 17, 2008 8:16 am

Re: Weight shift and thermal technique

Postby Ben H » Thu Nov 20, 2008 7:36 am

Simon wrote: I have always been told to use linked 360's, but haven't been one to abide by that.


Hey Simon, I think you will soon figure out the continuous 360 method as you start to fly other places with less wind.

I hope we get some action this weekend.

See Ya Dude,
Ben
Ben H
 
Posts: 66
Joined: Tue May 15, 2007 2:26 pm

Re: Weight shift and thermal technique

Postby trifco » Thu Nov 20, 2008 11:52 pm

Simon wrote: ....
From what I have deduced, added weight to one side of the wing alters the profile of that half of the wing. This creates more drag for that side of the wing, without changing the angle of attack, while the other wing counter-actively becomes more aerodynamic and accelerates faster than the loaded wing. The sketch is an exaggeration of a wing profile and a loaded wing profile....


Simon, I believe that your conclusion is inaccurate :? . The weight shifting does not "alter the profile" (airfoil cross section geometry), but the overall airfoil symmetry. Weight shift actually does two things at the same time - it shifts the center of gravity and creates "imbalance" in resulting lift vector of an airfoil (parallelogram anyone?). I think you can conclude in which way my illustration will start to turn :wink:.

Sincerely,
Trifco

weight_shift.gif
trifco
 
Posts: 2
Joined: Sat Nov 15, 2008 1:20 am

Re: Weight shift and thermal technique

Postby Simon » Fri Nov 21, 2008 6:48 am

I can go along with that, thank you trifco.

Here's another thermalling illustration

thermal technique 2.jpg


It's a variation of the last drawing. Thermalling like this gained me about 1000' when i was only a couple 100' over Bruces Point. I may have completed three 360 degree turns, dragging out the upwind legs.
User avatar
Simon
 
Posts: 73
Joined: Tue Jun 17, 2008 8:16 am


Return to Flight Discussion



Who is online

Users browsing this forum: No registered users and 14 guests