Many sites have constraints that require you to launch in a crosswind, unless the wind is straight down their runway. You must not only launch yourself safely, but also drop the winch cable and parachute etc safely.
In the previous lesson we described checking the wind for any crosswind element, and setting the controls accordingly – but we didn’t say how.
Determine the Crosswind Component
Hopefully you will have been aware of the wind direction before getting in the glider. The wind can change though, in speed and direction, so you must monitor it. You can check it by reference to:
- The Yaw String. Is it limp or blowing across or straight back over the canopy?
- The Wind Sock. There may be one at the launch point if you have a Control Bus etc. Is is pointing in line with your direction of launch? Is there a Windsock elsewhere on the airfield? How is it behaving? It is not uncommon on a hill site for these to be pointing in different directions at different speeds, due to curl-over, or perhaps just a thermal passing through.
- Have you flown earlier in the day? Have conditions changed?
Based on these clues, determine the crosswind component. If the wind is coming at you sideways at 20kts, it is 20kts. If the wind is from 45 degrees to one side, the crosswind component is reduced substantially – let’s say half. A 20kt headwind has no crosswind component, although you must consider what it is doing above you. Now check this against your glider’s limits. Most are certified for (launch and landing) in crosswinds of between 11-15kts. If you exceed these limits there is a possibility of having insufficient rudder authority to compensate during the ground run, resulting in a swing into wind and an unfavourable outcome as the winch drags you sideways.
Where will you land in the event of a launch failure – especially if you are too low to turn. Which way will you turn if you cannot land ahead? If you must turn, the best into-wind landing area may not be ahead of you at the launch – is the area clear, and is it likely to remain so for a few minutes?
A crosswind will cause your winch cable to land downwind of your release point. This could take the cable beyond the safe area ahead of you, resulting in it landing on buildings, property or people where it ought not to. This is the pilot’s responsibility, so you should be thinking in terms of laying off into wind as you progress up the launch. This requires a coordinated flight with the windward wing low. Monitor your progress over the ground, and follow local rules. Flying with the wings banked will cost you some height on the launch – you must accept this for the sake of safety.
There is likely to be some wind sheer as you climb, so anticipate a change in speed and direction.
Prepare to Launch
Prior to moving, set the rudder to yaw downwind, to counteract the otherwise inevitable swing into wind. Moderate rudder will suffice in a moderate crosswind. Be prepared to adjust with large control movements as you accelerate on the ground run, to achieve progress directly towards the winch.
Hold the ailerons neutral, possibly with some slight down force on the windward wing. Any down force is to prevent the wing being lifted after the wing runner releases it. Beware overpowering the wing runner – they must be able to hold the tip up, and should Stop the launch if they have any difficulty doing so.
Before launching, and with a wingtip on the ground, take a mental picture of the horizon ahead. If during the launch, a wing drops and the view starts to look anything like that picture, release immediately. It is extremely dangerous to drag a wingtip on the ground, especially so during a winch launch.
During the Launch
As you start to progress into the ground run, prepare to make large control movements to stay on track. For the first few seconds the glider will be strongly influenced by the wind, and any gust etc could easily roll or yaw the glider. Use the controls independently, and possibly fully, to maintain directional and roll control. Once airborne, use the controls in a coordinated manner, take a second or two to settle and see the speed build. When satisfied the winch is behaving, rotate gradually into the climb. Some people lay off immediately. I prefer to get established in the climb for a few seconds, and then make a coordinated turn to windward. Roll out, around ten degrees bank, and use rudder to keep the string central, whilst ensuring you are moving upwind. You’re unlikely to over-power the winch, but keep your other eye on the ASI and angle of climb. The controls will feel heavy!
Scenario and Demonstration
This demonstration takes place in a 15kt wind, crossing the nose at 45 degrees from left to right. It shows rudder being applied early in the ground run to avoid swinging into wind. This is followed by a good dose of left aileron to keep the into wind wing down. Large control movements are needed at the lower speeds. Once off the ground, level attitude in coordinated flight is achieved and rotation takes place as speed builds. The initial lay off is a bit excessive, as is apparent from the amount of ground in view to the left. A coordinated roll to the right brings it to a sensible position. Attitude is then maintained and the launch continues.
The video is best viewed in YouTube in Full Screen mode, to easily see the on-screen messages during the demonstration. Use view, pause and rewind as needed to grasp the content and timing of the messages displayed, then focus on the action.
Performing the Exercise
Trim for the approach speed you’ve chosen during ‘Eventualities’ – in this case a little forward of centre. Simply repeat the steps above! Practice the straight ground run and moderate lay off.
Condor’s winch behaves the same each time, unlike real life. With practice you can make a good launch in Condor – when this is repeatable, remember the “picture” but don’t hang on to the muscle memory – each and every launch will be different and must be flown accordingly.
Further Reading and References
Gliding From Passenger to Pilot, 2nd Edition: Page 115-118
BGA Instructors’ Manual, 4th Edition: Section 4, Chapter 16, Page 7
BGA Instructors’ Reference Cards: Ex 11b