Prevailing wind strikes the slope and as it cannot pass through the slope, it is then forced up and over.
It is in this section of upward moving air that LIFT is produced.
of lift produced is dependant on certain factors, such as windspeed, shape of
the slope and air temperature. A wind of 10-15mph is sufficient to create a
decent updraft, which is why slope soarers are able to attain height quickly
and then dive down, converting the height into speed.
A slope where the wind strikes dead-on (perpendicular to the slope) is ideal, as a side-on wind will greatly reduce the amount of lift produced by the slope.
A slope with a concave "Bowl" will compress the wind as it is funneled up the slope and create even better lift.
A good prevailing wind will provide hours of lift for slope soaring.
The lift-band can extend away from the slope for several hundred yards and way up above the top of the slope. This makes for a large flying area.
As the wind recedes, the lift will start to drop-off and then it is time to head back to land on top of the slope.
(Courtesy Atlantic Flying Club -- South Africa)
Slope Flying #101
If you are a first time flier, before going to a slope, go to the local park and practice throwing and gliding the plane flat and level into the wind. This will get you used to the controls so that corrections become quick and automatic because on the slope you don't get time to think about which stick to push in which direction. Before flying, check the basic functions, ie. up is up, down is down (stick forward) and right is right (right aileron as viewed from the rear of the plane goes up) and left is left. Make sure that the center of gravity is under the spar of the wing. These initial flights will also be a good opportunity to trim your model for straight and level flight.
When you have mastered level flight try some turns. As you turn you will need to add a small amount of up elevator to keep the model level. It is best to always turn into the wind as down wind turns can take up a lot of airspace; it can also be tricky to judge the correct airspeed.
Good soaring slopes are a little hard to find, however this makes an interesting challenge for this captivating sport. A good slope is characterized by the wind blowing straight up a slope that is steeper than 45 degrees. You will often see birds soaring in these areas. It is best to talk with local flyers or see where others are flying to find the best sites for each wind direction and strength. You can also then get first-hand tips on flying.
Choose a place to fly that offers a landing site. With combat models this is less important - just dodge rocks if you can. Long grass, or bushes are fine.
Thermals will also assist flying. Thermals are generated by sun the sun heating the land, warming air which then rises as it is lighter than surrounding air. This makes a sunny slope work better than a sheltered one. Most foam planes will fly well in winds from 10mph to 20 mph. Experts can fly outside this window. Before flying, ensure that your transmitter batteries are charged. Follow your radio manufacturer's instructions for proper safe radio operation. Always make sure that no one is on your frequency before turning your radio transmitter on. In any case, turn the receiver on first and make sure the control surfaces stay stationary after the initial glitch, this should confirm no-one else is on the same frequency.
When you choose a slope, have a good look around and imagine where you will fly, pinpoint areas such as trees and cliffs where you don't want to fly and decide where you will land. Before throwing off, check you radio gear by standing about 20 paces from the plane with the transmitter antenna pushed fully home.
Always throw off straight into the wind, straight and level and quite hard. Be ready to stop a steep initial climb by pushing the stick forward. Also be ready for a sudden turn to one side. Concentrate on keeping the model in front of you and heading away from the slope. If the model heads down and out from the slope, try pulling up a little. If the model continues to sink, land it before you loose it!
If the model climbs nicely but starts to go back over your head, push down to get speed up and hold down until you can fly it some yards in front of you. Once you are comfortable, try some zigzag turns, always turning into the wind. Remember to add up elevator when turning. Don't try fancy moves, just concentrate on getting your hours up. Practice, practice, practice. Note bad areas are below the horizon and down wind of you. This will put you out of the lift in into turbulence.
Good luck, and
have fun flying.... !!! Dave Griffin -- New Zealand