Is the wind strong enough?

[petedaws]

I stopped by Hastings Pt (near Cabarita) to fly my Skua a couple of weeks ago. The wind felt fairly strong so I launched. Rather than just float in the "lift pocket" just above the slope like it normally does, it kept going, out and out, over the rocks and nearly over the ocean, until I got a bit scared and ditched it on the rocks.

I'm guessing this happened because there wasn't enough wind, however the Skua really didn't lose too much altitude as it glided out from the slope. All other times when I have flown, I have been able to keep the Skua almost stationary in the "lift pocket". I have always imagined slope soaring to be exactly the same as a wave machine....

Its kinda like floating on a fountain of air.

If the water wasn't moving fast enough, they just wouldn't be able to stay on. Is this how it works for us or is it possible to do some tricky flying to stay airborne and close to the slope?

What should I have done in this situation? Not flown at all? or weaved it back and forward across the edge of the slope.

How do folks check if the wind is strong enough before launching?

[Pij]

I think, in marginal conditions, that slope soaring is like riding over a NUMBER of small fountains. Generally you would need at least 2 "fountains" of uplifting air, if they were small. Make one fountain your left-turn point, and the other your right-turn point.

Then, when you're making your endpoint turns, which might otherwise be a manoeuvre which loses height, you can instead GAIN height in the turns. These end-points are where you stay the longest, due to lower speed and due to the turn, so it makes sense that you tarry in the best lift while you do it.

In between the turn points, you should scoot along pretty briskly, so you get through the no-lift zone as quickly as possible, to reach the lifty turning point at the other end for another boost of height, which you again turn into airspeed as you make the return trip.

So, for me, if I launched and didn't find the big bubble of lift I expected, I'd quickly fly parallel to the cliff till I did get lift, and make my turn there, then back to the other end looking for another lifting patch.

[thevon]

Pete, I have to disappoint you by saying that your concept of slope flying "stationary" in the wave isn't the norm. In certain conditions when the cruise speed of your plane perfectly matches the wind-over-ground speed, the plane will stay still but a small change in the windspeed, wind direction etc and you'll be going forwards or backwards.

Think of the area in front of the slope as a band of lift, and you need to spend as much time in it to get the lift you need. Zigzag from left to right, and make each turn into the wind (never downwind until you get lots more experience). So you're doing long figure 8's.

Checking wind strength is something you have to get a feel for and it depends on the plane and the characteristics of the slope. On a near vertical slope in a bowl shape (like Cabarita) with a light lifty plane, you may be able to fly in barely a breeze. But on a more gentle sloped isolated hill (where the wind can separate and go around the hill) and a heavier, less lifting wing you may be struggling to get enough lift even though it's over 20 knots.

Hope that's some help!

[combatnoosa]

Mar 17, 2009 18:10:39 GMT 10 thevon said:

Pete, I have to disappoint you by saying that your concept of slope flying "stationary" in the wave isn't the norm. In certain conditions when the cruise speed of your plane perfectly matches the wind-over-ground speed, the plane will stay still but a small change in the windspeed, wind direction etc and you'll be going forwards or backwards.

Think of the area in front of the slope as a band of lift, and you need to spend as much time in it to get the lift you need. Zigzag from left to right, and make each turn into the wind (never downwind until you get lots more experience). So you're doing long figure 8's.

Checking wind strength is something you have to get a feel for and it depends on the plane and the characteristics of the slope. On a near vertical slope in a bowl shape (like Cabarita) with a light lifty plane, you may be able to fly in barely a breeze. But on a more gentle sloped isolated hill (where the wind can separate and go around the hill) and a heavier, less lifting wing you may be struggling to get enough lift even though it's over 20 knots.

Hope that's some help!

I have found that a good indicator around where I fly is when the sea gets choppy, on my way home I look for little waves all over the sea and this normally will provide enough lift for where I fly at sunrise beach, the slope there is about 20 - 25m above sea level and has an average gradient of around 45 deg naturally as the gradient lessens the speed of wind needs to increase to produce useable lift, what I think might have happened with your adventure is that you had passed through the lift area into the largely uneffected wind and hence lost altitude.

Another way to test for wind speed is using a small hand full of grass or leaves and throw them in the air, count seconds it takes to hit the ground and measure the distance traveled, you can work off meters a second then, say if from the time you threw it to the time it landed took 5 seconds and it landed 10 meters away from you you could expect that the wind was traveling at the rate of 2 meters a second and that multiplied by 60 will give you meters a minute wich is 120 meters a minute and then times that by 60 again which will give you 7.2 km an hour. you could do all this or just check this
www.bom.gov.au/jsp/marine/wind/index.jsp

Regards,
Jay