Ha! That got your attention quickly enough didn't it? If it didn't it should have done. The real questions are really 'Can we fly slowly and safely?' and 'Do we want to fly slowly anyway?'

Let's start with the second question. Here are some reasons why we might want to fly slowly:

• In order to spend as long as possible in a patch of rising air.



• When scratching to stick as close as possible to the slope giving us slope thermals.

And here are some reasons why not:

• We are more susceptible to turbulence when flying slowly, particularly to tucks and being stalled or spun.



• Our gliders perform best somewhat above their minimum speed, usually best sink rate is not far below the speed for best glide.

If we consider the pressures on the surfaces of our wing we have three elements to consider:

• Pressure above the top surface of the wing.



• Pressure inside the wing.



• Pressure below the bottom surface of the wing.

For a 100kg all up weight paraglider of 30 square metres if we assume two thirds of the lift comes from the vacuum above the wing these pressures might look like this:

Inflation Pressure = Atmospheric + 1.9 kg/sq.metre at 20kph. (near stall)
                   = Atmospheric + 4.3 kg/sq.metre at 30kph. (min.sink)
                   = Atmospheric + 7.6 kg/sq.metre at 40kph. (brakes off)

Notice that the 'lift' pressures above and below the wing are averages of atmospheric - 2.2 and + 1.1 kg per square metre respectively. The absolute pressures will vary chordwise and spanwise. Note too that the inflation pressure varies as the square of the airspeed whereas, for a still air glide, the average pressures above and below the wing are the same at all speeds. (The distribution of pressures above and below the wing may vary but the average should stay the same.)

Our wing is kept in shape partly by the 'lift' pressures and partly by the inflation pressure and we can see that at high speeds the inflation pressure is considerably greater than the average 'lift' pressures. However, at low speeds the inflation pressure falls to a value much closer to the 'lift' pressures and we may be nearing the condition where the wing, or at least part of the wing, is kept in shape as much by the 'lift' pressures outside the wing as the inflation pressure inside. From here we might begin to see how, when we near the stall, we risk not only losing all our lift but also the structure of our wing.

All very well, I hear you say, but how does that help me know how hard to pull the strings? It can help us but first let's have a look at pitch stability. We have pendulum stability, but is that the whole story? No chance. If we are in a straight glide with the brakes completely off and then pull them on quickly we know we will swing forwards which will pitch the canopy up and may cause a 'dynamic' stall. We know that if we pull the brakes on slowly this will not happen and we simply stabilise at a slower speed.

Consider our two reasons for flying slowly. There we are scratching along a mountainside in weak lift with occasional patches of stronger lift which we want to slow up in. In our eagerness to slow up we pull fairly hard on the brakes and as we swing forward under the canopy the resulting increase of pitch makes the airspeed fall quickly. At this point we inconveniently, but typically, reach the other side of the lift patch. We find ourselves dropping with low airspeed, poor inflation pressure and our canopy considerably pitched up. What should we do? Turn away from the hill? With poor airspeed and the canopy pitched up we may risk a spin. Let off some brake to regain airspeed? We have a delay whilst the canopy surges forward (or we swing back) to a position of reduced pitch.

The answer is, of course, that we shouldn't be in that situation. We should always have some airspeed in hand to cope with these inconveniences and make our changes of airspeed smoothly so that we don't swing too much (unless the swing is an intentional part of the manoeuvre). If in the above example we had smoothly pulled on rather less brake we would still have had plenty of airspeed when we felt the lift drop. This would enable us to either simply continue on along the slope or, if we felt it worthwhile, to make a turn back into the area of lift. There is no reason why, if it suits our purpose, we should not let some brake off on entering a patch of lift and use it to boost our speed instead of our height.

Most handling problems usually come back to airspeed in one way or another. If you are having problems try looking at your airspeed. It's usually the answer.