Schlagwort-Archive: Thermikfliegen

First Climb

If you’re a winch pilot, you probably know this all too well, if you haven’t built a small plan before take-off, your flight might end up with a circuit and another launch. For a flight to be successful we must first think about where to go once we release the cable or tow plane.

Plan before Takeoff
The easy way to start this process is to select a promising-looking cloud shortly before launch, a sure advantage. Why so? Because you are already ahead of the eight-ball when it’s time to start making soaring decisions, often at low altitudes. Once we release, we must look for it again and assess whether it’s within reach or not. If not, have you picked a backup cloud or ‘house’ thermal to go to? If it is, keep flying towards it while refraining from turning in anything unless it’s a certain lift – always remember though, we must keep gliding back to the airfield with landing height options to spare!

Staying Airborne
So with the limited height and time available, we have to get crafty. We also have to remember that it’s not a race at this point, we just need to stay airborne so we can have the opportunity to soar for the day. We should head to our target cloud at the best glide speed or near enough to it.

The same applies to aero-tow too, however, we have a much greater chance of finding lift as we’ll be sampling it on the way up, we will be taken closer or further away at our request, and finally, we can always release when we go through a thermal. If the tow plane starts climbing faster than the average on the way up, it’s likely you’re in a climb. I personally try to stay on to 2000’ to simulate a competition tow, but you may want to get off early to practice a low save.

After Release
After release though without a thermal, we practice the same as the winch pilot or we can backtrack to those thermals felt on tow, use caution though, are there other tows inbound on that standard path – lookout out always! Thermals are often wider in diameter and easier to stay in, so a higher tow is often easier again to get away from. Try to head upwind, so that you are drifting towards the home airfield. Our best chance of finding lift is to approach the cloud or hotspot into the wind, this might sound difficult to do, but when downwind straight after release, we don’t care about the wind at altitude, so use the ground wind for now, plus your gliders instruments will help if you have the appropriate ones on board – an Oudie N is excellent for this, the Oudie will also help with having return to airfield glide information too

The first thermal of the day doesn’t have to be the strongest, we just want to stay up, sample the air, and build our picture of the thermal structure for the day. Remember, it takes a verrrrry long time to lose 1000’ when you’re thermalling in 0.1kt sink – so if you need to buy time while you wait for someone else to help you look for a thermal, this is a good tactic to use, when the other finds a useable climb nearby, you can choose to leave or stay. Source: ‚Wings & Wheels‚.

How to join thermals

If we are going to be seen by the other glider and keep the other glider in sight, we must first understand the blind spots that gliders have and – more importantly – the situations that might lead to both gliders being in each other’s blind spots.

Before we consider sharing a thermal we will have to think about how we are going to join a thermalling glider. This is where we will need to make certain assumptions. The first assumption is that the circling glider has found a good climb and is already centred on it. This means that no time will be wasted trying to centre the thermal once we join. In order for this to work, it is vital that the other pilot stays in the core and can concentrate on centring it without having to worry about avoiding you.

If we join the thermal in such a manner as to alarm the other pilot then they may move their turn to give them greater separation or comfort; this means that they lose the thermal core and you have to waste time recentring the thermal. In other words: you’ve blown it. Apart from the obvious disadvantages of a lower overall climb rate, the consequences of joining a thermal badly can be that we conflict with the other glider, increasing the risk of collision.

This risk can once again be minimised by a few basic rules:

  • The first glider has right of way
  • Join the thermal so that you turn in the same direction
  • Join in such a manner that the other glider does not have to manoeuvre in order to avoid you
  • If there is more than one glider and they are thermalling in different directions then turn in the same direction as the one closest to your height

The perfect join is one that places you exactly opposite the other glider, sufficiently far away so that you can remain opposite them with a comfortable angle of bank and speed (see diagram, above right). Before we can do this we must first assess the extremities of the other glider’s turn. This is easy to do but rarely explained. Simply watch the other glider’s turn until you can see it rear-end on, then mark a point on the horizon, which will then mark the boundary of its turn. Provided we fly towards this point we will end up intercepting their turn at a tangent (assuming they don’t alter their turn). If it looks likely there will be no conflict then continue on into the turn (see above page, left) keeping the other glider opposite you.

This method of joining another glider sounds simple enough but is in fact rather difficult to do, and the chances of entering the thermal when the other glider is not opposite you are high. If this looks like the case then we will need to enter the thermal in a spiral fashion. Source: ‚British Gliding Association.