Go Back   OhioFlyers.org > Safety & Know-how

Thread Tools Display Modes
Old 02-02-2009, 08:13 PM
Michal M.'s Avatar
Michal M. Michal M. is offline
Join Date: Feb 2009
Location: Indiana
Posts: 1,033
Thanks: 602
Thanked 142 Times in 84 Posts
Default Ridge Scratching

Small-Ridge Scratching
By Pete Lehmann

Scratching can be defined as soaring on a light-lift day by making optimal use of every bit of available lift. Within that term one can differentiate between two kinds, ridge and thermal scratching. This article will only address ridge scratching as it is the crucial skill for a pilot wanting to soar Templeton (480ft agl) and Avonmore (430ft agl). Our small sites seldom produce idiot-proof soarable conditions. This means that on light- and/or cross-wind days there will be little ridge lift, and what lift there is will be found close to the ridge. If you want airtime on such days you will have to fly closer to the hill than you have been accustomed. This is not to say that you will have to spend lots of time near the trees. It is commonly true that conditions can be marginal at launch height, but fairly good only 50-100ft above the ridge top. After as little as one close pass on the ridge you will be able to climb into the better air. The key, of course, is the ability to safely accomplish those first few passes, and this article is intended to serve as a guide to safely learning the skills to achieve those difficult first passes.

There exists a misconception that the primary scratching requirement is an oversized set of balls. While it is undoubtedly true that a fearless pilot will fly closer to the hill than will someone with a more healthy respect for tree rash, it misses the point that scratching is a learnable skill like everything else in the sport. A nerveless, but ignorant, pilot may be willing to get close to trees and rocks without possessing the knowledge to scratch intelligently. Proximity to the hill is only a part of scratching, and it is the one most likely to get you into trouble.

How Does One Learn to Scratch Little Hills?
Practice, Practice, Practice
To be blunt, one must try to soar on light days. Sitting on the hill waiting for it to “get good” teaches nothing. You need to gain experience, and if you are afraid of sled rides you will not learn to scratch. The corollary is that the more you master scratching the less sled rides you get. Before becoming a proficient scratching pilot you will certainly often feel like a fool sitting in the landing field while more experienced pilots soar. But you must keep in mind that they too began as clumsily as you, if not more so. When they began flying not much was known about soaring small ridges. By combining their experience with your enthusiasm you can learn much more rapidly than they did. Do not be afraid to ask for advice, but, more importantly, don’t hesitate to gain your own first hand experience. You will surely screw up a lot, but only by trying will you learn. Just be certain that the mistakes you make are not safety related.

Knowing One’s Ridge
Lift characteristics are highly dependent on the shape of your local hill. Consequently there will be a definite pattern to the locations of lift and sink spots, and to their changing relationship to variations in wind direction and velocity. Lift patterns will even vary with the seasons as the presence or absence of leaves alters the effective shape of the ridge. Keep in mind that because you will be flying close to the hill you will be subject to extremely localized changes in air texture. Each little face or spine will have a bit of lift, sink or turbulence associated with it. Because of the important role played by these contour changes in determining the location of lift and sink it is necessary for you to develop a mental image of the ridge’s shape. You can then use that picture to plan your first pass on the ridge.

Before launching you can combine your image of the ridge with what you know about the day’s conditions: wind velocity and direction, bird behavior, cloud characteristics and the successes of other pilots. With this information you can now plan your flight. What criteria will you use to pick a launch time? Which way will you turn, right or left? How far down the ridge will you go before turning? Are you going to just stay in one bowl or section of the ridge? How low will you let yourself go before heading out to land? Think about how you will have to set up your landing approach.

Your plans will likely be very wrong at first, but they will give you a framework on which to build your scratching knowledge: “The last time conditions were like this I went left and it didn’t work. I’ll try it to the right this time”.

Picking Launch Cycles
Observe conditions while you are setting up. Watch for a relationship between clouds and cycles, sun and cycles; bird behavior (turkey vultures are poor indicators, but hawks are excellent), wind lines on water, directional changes and velocity changes. Most sites have particular local indicators that can be useful. At Templeton, for example, one pays close attention to swirls and wind lines on the river. And if the evergreen hemlocks to the right of launch are moving steadily it is soarable.

After setting up, hook-in and go to launch. On a light day useable cycles may be very short, and there may be as few as two or three a day. You will not have time enough to observe the beginning of a cycle, hook-in, do a hang check and get off in it. You need to be all set and ready to go when a cycle begins. Ideally you should hook-in directly behind a proficient, experienced pilot whom you can pimp. If he gets up and presents no mid-air hazard, launch.

If you’re on your own without the luxury of pimping an experienced pilot, decide on what will constitute a good pattern, watch for it and launch. You will never be sure if it is the right time, but each launch you make will fill in your data banks and improve future assessments. Sitting on launch teaches you nothing.

Be prepared for sled rides. Your inexperience guarantees that you will screw up a fair bit. Because you are likely to make some sled rides, prepare for them by shuttling some vehicles to the bottom or asking if someone can come and get you if you break down quickly. One advantage of small sites is that the turn around is short if you hustle your break down and set-up. That means that the penalties for taking a shot at soaring are not too severe.

The Mechanics of Scratching
1. Launch hard. Every foot of altitude conserved counts, and you want to have good speed near the hill.
2. Turn immediately to stay close to the ridge. Lift bands are very narrow on light days.
3. Follow the ridge’s contour. If the ridge drops back a bit, let yourself fade back with it to maintain a constant distance in front of it. This is especially true of the big hill to the right of Templeton’s launch.
4. Fly with extra speed. Do not cruise pushed out near a ridge. The lift there is uneven, with pops of lift quickly followed by sink and turbulence. The extra speed is the safety margin that prevents you from being abruptly stalled. It is also the energy reserve you need to maneuver to avoid problems caused by turbulence turning you at the hill. A good speed to fly is somewhere between minimum sink and best glide speeds. Be careful not to fly too fast as that will drastically worsen your sink rate.
5. Always leave a way out, and use it the instant you feel the slightest push into the hill. Try to avoid pointing more than a few degrees at the hill.
6. Turn in lift. This is the cardinal rule of scratching. A turning glider is inefficient, and turning in sink is that much worse. The best result is obtained by turning in lift while bleeding off a bit of the extra speed you carried gliding along the ridge.
7. Be flexible. With even slight changes of direction and velocity the lift locations can move. As lift moves around make sure you don’t stubbornly keep doing what worked on the last pass along the ridge. Adapt to change.
8. Look ahead for indicators. Are the leaves moving more (or less) vigorously? Did a hawk just come out of the trees? Are the gliders ahead of your doing better (or worse). At Templeton it is always a good idea to keep an eye on the river’s surface. It is a wonderful indicator of coming changes in wind direction and velocity.
9. Remain alert for thermals. We only rarely fly in pure ridge lift. Those bumps close to the hill are often not “turbulence”, but thermals. With experience you will gain confidence in determining how best to work them. But the essence is that if it is lifting, turn or slow down in it. At scratching altitudes you will likely need to use a combination of quick turns, S-turns, figure eights, etc to slowly climb above the ridge before beginning to 360. It is critical that you not fly too slowly while still close to the hill.

Finally, these skills are universal. They have been described with respect to the author’s two local sites. However, they are equally valid at any other site, large or small. When travelling to a new site you will again be in the position of a Hang Two seeing a site for the first time. In the same way you will repeat the essential steps outlined above: examine the hill’s shape, matching it to the day’s winds; plan how to exploit its lift producing faces; carefully pick a cycle, and after a strong launch fly the hill with a subtle mix of awareness and aggression.
Attached Files
File Type: doc Ridge Scratching.doc (30.5 KB, 2 views)
File Type: pdf Ridge Scratching.pdf (63.4 KB, 3 views)
Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -5. The time now is 05:35 AM.

Powered by vBulletin® Version 3.7.3
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.

Skin design by bogu@project-voyageur