I have the privilege to be part of different “worlds”, the one from the pilots, the one from the instructors, the one from French pilots, the one from German pilots, etc… I have also the privilege to have made quite some outlandings in my pilot’s life, and even if they were not perfectly made, one thing probably saved me and the glider few times : to be able to land precisely. And… I am not very happy with the many landings I see around me on different airfields! I would even say I am angry!
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Why? First, for me, there are 2 typical phases, moments, minutes in a flight were you need to be focused and as precise as possible. These 2 phases are obviously when you are close to the ground. Ground is there, danger is close, groundloop, hard landing, too short, too long, cable failure, tug/winch failure, … We all know the many examples where a glider can be crashed in few seconds. So, again, for me, you can be quite distracted in the air, you can make “something else” from time to time, you can be “not so precise” many many times too, BUT NOT WHEN LANDING AND TAKING OFF.
So, again, for me, you can be quite distracted in the air, you can make “something else” from time to time, you can be “not so precise” many many times too, BUT NOT WHEN LANDING AND TAKING OFF.
Stay Focused
So, for this report, I will focus on landing only. I am from France and we are lucky pilots there : the government had for years been involved in gliding as part of pilots training (military and commercial) so some public employees made a huge job. They wrote a book! A bible I would say, it is called “le Livre Bleu” (the Blue Book) and is the all-in-one-book-to-become-glider-pilot you need, period. Questions about basics of gliding is in for sure, but also introduction to weather, airspace, safety, technics, etc… All in one! The philosophy of the glider (and aircraft) pilots who wrote it is to make you a “professional of gliding” in a soft way. So no super hard and deep theory, simple things, adapted to our world of gliding. In this book, you will find a very deep chapter about landing, explaining patterns, angles from the cockpit view, approach speed, use of airbrakes, etc.
Back to where my angriness is coming from. Too many times I see a little “urgency” in landings like there is some bad stress in the cockpit and, after having pushed back the moment the pilot finally enters the downwind, then there is a wish that this ends as soon as possible. We learn, in our “Blue Book” that time is the key. Time is key to prepare landing (spot what happens on the ground, check who is also in or close to the landing patterns, prepare the glider for a proper landing configuration), time is key to make a precise landing (make adapted legs pattern and design it to have enough time on final leg). We learn also that landing is not finished when the wheel touches the ground, still you will need to stay focused for a little while and understand what is going on… So yes, I am angry.
Speed is life?
Ok first for today, let’s talk about speed. We all hear this little music when we learn to fly “speed is life” they repeat, so we all want to have this extra energy when landing to avoid a hard landing. I agree, fully, but when this little amount of overspeed is growing to too much speed, don’t ask yourself why when you pull the stick to avoid the ground (flare), it takes ages to land, or worse if you are not gentle you get a very nice pull close to the ground which is not the safest way to land. So first let’s go back to why we put extra speed when we land.
Our “Blue Book” is clear : you need this extra speed to avoid a hard landing (stall). You can imagine that yes, flying close to stall speed (with already a big sink rate added to the use of airbrakes) will give you no chance to “level the flight for a while” (flare) when you are the closest to the ground, it would be a I-pull-it-stall-boom. This is why we don’t use as landing speed a close to stall one (plus maneuverability aspects). So our book states : “in landing configuration, you should be closest to 1.3xVsl as basis for landing speed. This speed is called Optimal Landing Velocity (VOA in French)”. In clear? In the air, high, put your gear down, set the flaps to landing position, airbrakes out, and check at what indicated speed the glider seems close to stall. This is your today’s real Vs in landing configuration on this glider with this Center of Gravity setting. Pour a top up of 30% on this Vsl and that’s it! Many pilots will tell me “Hey Benj, it is written on the Speedo with this little yellow triangle so why calculate it?” And I will reply “Sorry, wrong, this little triangle is for max weight of non-lifting parts (with no water ballast), which means a lot of time 110kg in the cockpit and a nose Center of Gravity”. Are you these 11 stones? If yes then this yellow triangle will help, if you are not you can land slower (by quite a margin if you are below 75kg with parachute!). So be nice with me, and next time you fly your beloved glider, before landing, check your real Vsl in landing configuration and extrapolate the accurate Optimal Landing Velocity!
Then, from this basis, our “Blue Book” now introduces one element we meet everyday : the Wind. Why? Well, wind will not change anything when you are in the air, not close to the ground, but there is one problem coming when you come closer and closer to the ground : wind will drop for quite a lot due to interaction (drag) with the ground (it is called wind gradient) and can lose around 50% of its velocity in the last very few meters high! Damn! Damn why? Simple : a glider is a lightweight aircraft, this means it does not fly exactly the way a big heavy commercial aircraft flies. In a word, it has very little inertia so when nose wind drops in a snap, our little glider will also drop dramatically in its proper airspeed (total energy) and can meet, because of that, its stall speed violently. And when flying around 1-2 meters high above the ground, it is not the greatest idea of the century. So let’s, from this basis landing speed of 1.3Vsl, add a bit of extra energy due to this expected drop of windspeed close to the ground (where you will flare…), and make it 50% of the wind indicate by the top of the windsock…
Example : my Discus-2c FES wilth gear down and airbrakes out and me inside is starting to stall at around 78km/h IAS, So I need to use as landing speed in calm air of 101km/h (official yellow triangle is 110km/h…). And today windspeed on the airfield is 10kts (around 20km/h) so I will land as close as possible to 111km/h IAS. Without testing myself the behavior of the glider in the air, I would have used the yellow triangle indication, so landed at more than 120km/h which makes a big difference during the flare : time to reduce the speed in the air will be longer (so the total landing length) and technic to avoid a pull due to this extra energy will have to be used.
After more than 3000 flight hours in a glider I can tell you this method is spot on!
Some annoying guys here?
But some will tell me “Hey Benj, why bother so much with landing speed, the airfield is huge so we can land with a bit of extra!” Let’s be clear : one day, you will have to outland, and this day the field you have to land will perhaps be way shorter than you’d like, so if you don’t train to land precisely and short during all your landings on your airfield where the level of stress is very low, good luck to be the most precise possible the day you will need to be under hard pressure…”
Another annoying guy will object “Hey Benj, but there is no windsock on a landing field so your bla-bla is not worth to read it!” And I will have to answer : you are totally right, but only in the first part of your sentence : there is obviously no windsock on a landing field. But wind is quite stable (except in Mountain area), so the forecast of wind you had from the briefing in the morning will give you a first nice idea about direction and strength. Plus, if you are circling before outlanding, if you don’t notice any drift, wind is close to null. So this plus that plus the way wind makes waves on crops and flip the leaves on the trees will make you an happy pilot with a close to perfect landing speed.
Final words
A last word? Yes, important : when to apply this Optimal Landing Speed? I see some pilots using way more speed than this in downwind and base leg, slowing down only on Final. It is ok in a way as this speed should be applied in the last few seconds in theory, BUT if you fly faster in downwind and base leg you skip one of the point I talked about on the beginning of this post : TIME! You need time and this overspeed makes everything faster which is not at all the goal. Also, more speed on downwind means a ground speed very fast as you have also tail wind, which is again not the best to manage first turn to base leg in a smooth and precise way. And finally, there is one thing we use on daily basis in a glider to keep a steady speed, it is the sound the glider makes, so the soonest you use this landing speed when you prepare the glider to land, the best your hears are becoming used to the sound, your body to the behavior of the glider at this landing speed, the easiest it will be to land with the proper speed in a smooth way.
Happy 2021! Happy landings!
PS : the day the field is very short, use 1.2Vsl, it will not be smooth but it will be ok…
You enjoyed these 7 minutes reading?
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