What are the best places to gain the most altitude in a glider? Announcing the arrival of Valued Associate #679: Cesar Manara Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)How to pick a good airfoil based on Cl and CdHow are thermals found?Why do glider licences have fewer restrictions than powered aircraft?How can the Perlan II glider climb to 90,000 feet?Does a headwind affect the climb gradient?What's the maximum bank angle of a glider?How can we calculate the benefit gained from taping glider wing roots?What is the best distance glider that can carry a 200 lb load?How does an increase in climb rate affect climb gradient?What would the altitude profile for a typical airline flight look like?Why is polar curve of a glider dependent on flight load?
What does "lightly crushed" mean for cardamon pods?
Can anything be seen from the center of the Boötes void? How dark would it be?
What does this Jacques Hadamard quote mean?
Crossing US/Canada Border for less than 24 hours
How do I make this wiring inside cabinet safer? (Pic)
What would be the ideal power source for a cybernetic eye?
Maximum summed powersets with non-adjacent items
Withdrew £2800, but only £2000 shows as withdrawn on online banking; what are my obligations?
Wu formula for manifolds with boundary
How to compare two different files line by line in unix?
When coming out of haste, do attackers have advantage on you?
Why do the resolve message appear first?
How could we fake a moon landing now?
What is this building called? (It was built in 2002)
How do I stop a creek from eroding my steep embankment?
How to show element name in portuguese using elements package?
How to tell that you are a giant?
Why aren't air breathing engines used as small first stages
What is the meaning of the simile “quick as silk”?
Ports Showing Closed/Filtered in Nmap Scans
Does classifying an integer as a discrete log require it be part of a multiplicative group?
Closed form of recurrent arithmetic series summation
Circuit to "zoom in" on mV fluctuations of a DC signal?
How can I use the Python library networkx from Mathematica?
What are the best places to gain the most altitude in a glider?
Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)How to pick a good airfoil based on Cl and CdHow are thermals found?Why do glider licences have fewer restrictions than powered aircraft?How can the Perlan II glider climb to 90,000 feet?Does a headwind affect the climb gradient?What's the maximum bank angle of a glider?How can we calculate the benefit gained from taping glider wing roots?What is the best distance glider that can carry a 200 lb load?How does an increase in climb rate affect climb gradient?What would the altitude profile for a typical airline flight look like?Why is polar curve of a glider dependent on flight load?
$begingroup$
I'm a beginner pilot and I started with gliding. How to spot the best thermals and what is the most efficient way to climb?
glider climb thermals
New contributor
$endgroup$
add a comment |
$begingroup$
I'm a beginner pilot and I started with gliding. How to spot the best thermals and what is the most efficient way to climb?
glider climb thermals
New contributor
$endgroup$
1
$begingroup$
Follow the birds. Circle where they are circling. Upwind side of a mountain, or a ridge. Large dark areas on the ground. Also check with other glider pilots in your area for good local spots.
$endgroup$
– CrossRoads
5 hours ago
1
$begingroup$
Welcome to aviation.se! Welcome to Stack Overflow! Please take the tour, have a look around, and read through the help center, in particular How do I ask a good question? and What topics can I ask about here?. -- Answeres to your question should be part of your glider pilot training.
$endgroup$
– Timothy Truckle
4 hours ago
add a comment |
$begingroup$
I'm a beginner pilot and I started with gliding. How to spot the best thermals and what is the most efficient way to climb?
glider climb thermals
New contributor
$endgroup$
I'm a beginner pilot and I started with gliding. How to spot the best thermals and what is the most efficient way to climb?
glider climb thermals
glider climb thermals
New contributor
New contributor
edited 1 hour ago
Sean
6,25632979
6,25632979
New contributor
asked 5 hours ago
Wojciech KacprzyńskiWojciech Kacprzyński
313
313
New contributor
New contributor
1
$begingroup$
Follow the birds. Circle where they are circling. Upwind side of a mountain, or a ridge. Large dark areas on the ground. Also check with other glider pilots in your area for good local spots.
$endgroup$
– CrossRoads
5 hours ago
1
$begingroup$
Welcome to aviation.se! Welcome to Stack Overflow! Please take the tour, have a look around, and read through the help center, in particular How do I ask a good question? and What topics can I ask about here?. -- Answeres to your question should be part of your glider pilot training.
$endgroup$
– Timothy Truckle
4 hours ago
add a comment |
1
$begingroup$
Follow the birds. Circle where they are circling. Upwind side of a mountain, or a ridge. Large dark areas on the ground. Also check with other glider pilots in your area for good local spots.
$endgroup$
– CrossRoads
5 hours ago
1
$begingroup$
Welcome to aviation.se! Welcome to Stack Overflow! Please take the tour, have a look around, and read through the help center, in particular How do I ask a good question? and What topics can I ask about here?. -- Answeres to your question should be part of your glider pilot training.
$endgroup$
– Timothy Truckle
4 hours ago
1
1
$begingroup$
Follow the birds. Circle where they are circling. Upwind side of a mountain, or a ridge. Large dark areas on the ground. Also check with other glider pilots in your area for good local spots.
$endgroup$
– CrossRoads
5 hours ago
$begingroup$
Follow the birds. Circle where they are circling. Upwind side of a mountain, or a ridge. Large dark areas on the ground. Also check with other glider pilots in your area for good local spots.
$endgroup$
– CrossRoads
5 hours ago
1
1
$begingroup$
Welcome to aviation.se! Welcome to Stack Overflow! Please take the tour, have a look around, and read through the help center, in particular How do I ask a good question? and What topics can I ask about here?. -- Answeres to your question should be part of your glider pilot training.
$endgroup$
– Timothy Truckle
4 hours ago
$begingroup$
Welcome to aviation.se! Welcome to Stack Overflow! Please take the tour, have a look around, and read through the help center, in particular How do I ask a good question? and What topics can I ask about here?. -- Answeres to your question should be part of your glider pilot training.
$endgroup$
– Timothy Truckle
4 hours ago
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
First, you need practice. Take every opportunity to expand your experience. Theory helps but will never compensate for missing practical experience.
But then you also need to know how thermals form. Let's start low, close to the ground. Two things are important: A chance for the sun to heat the ground (and, consequently, the air above), and an opportunity for that heated air to ascend. Dry ground will heat up better than moist ground, and dark earth better than light sand. If the ground is completely featureless, the air will stay on the ground. So you need to find the trigger which determines where air starts to rise up. Once it does this, more air will be sucked in from the side, and will follow up. That is how a thermal starts.
And that summer gust, which is the horizontal motion of more warm air flowing towards the point where a thermal starts, should indicate to you that now you have a chance to stay up, so now you need to get into your glider. Early in the day the thermals will not go high, so don't be impatient. On the positive side, there are many thermals and a good chance of finding the next one quickly.
Once in the air, look for triggers. One of the easiest is a windward edge of a forest. Warm air is driven towards the forest by the prevailing wind, and the trees will push the air up, kickstarting its ascent. Fly along and a bit leeward of the ringe and you can't miss the thermals there. But even a closed forest is a good source of thermals: The dark trees heat up well and the air between the trees heats up quickly. A small elevation is normally enough to start a thermal. In the mountains, a windward ridge is also an obvious trigger, and it is advisable not to drop below the height of the lowest ridge, as you suddenly might find yourself unable to find any more thermals.
Once higher up the ground features become more and more unimportant. For one, wind is shifting everything sideways, but also now the large-scale vorticity which forms the clouds dominates where the thermals form. Think of cumulus clouds as giant thermal vacuum cleaners which collect the rising air from all around. But not any cumulus cloud: Most promising are the ones which grow, have sharply defined edges and a dark bottom which is bulged upwards towards the center. Flee from the fuzzy ones with a round bottom: They have lost their pulling power and are about to disappear.
Why the bulged-in bottom? THAT is where the heated air goes up and pushes the bottom of the cloud up. But what goes up must come down: In the vicinity of the best clouds you will also find the worst downdrafts. Fly through those quickly and pull up as soon as the downdraft stops.
If you fly cross-country, the most important knowledge is in which direction the wind is blowing. If the wind is strong enough (more than a soft breeze), thermals will line up in wind direction, so you can just leave one straight into the wind (or with the wind) and be sure to hit the next one shortly. This works particularly well if there are no clouds to follow (blue thermals). Just remember where exactly that one-before-last thermal was and fly off in exactly the opposite direction. When that brings you too far off the planned course, cross the valley of downdrafts orthogonal to the wind direction until you arrive in the next lineup of thermals.
Now to how to circle properly. A glider will fly at its minimum sink speed when induced drag is three quarters of total drag - given the high aspect ratio of gliders this means at a really high lift coefficient. Close to stall. Therefore, it is most important to learn how the glider warns you that you are about to stall. Also, some gliders will happily let you fly in a stalled condition (the Discus is a prime example) with really poor sink speed but without loss of control. Go up to maybe 1000 m and then stall the glider slowly. Learn how that feels. Then continue with circles. Stall the glider again. At some point you will feel how the stick forces lighten (that is when flow separation starts on the ailerons!) and you will learn to fly just a bit faster than that. Similarly, the stalled Discus has really soft and mushy controls - fly faster until the controls feel stiff again!
Since circling with more than 45° of bank is rather stressful, fly between 30° and 45° of bank angle. You need to catch the core of the thermal, where the climb speed is highest, and banking more is worth the tradeoff in many cases. Tighten the circle when the climb speed decreases and widen it when speed increases - that helps you to center your circling with the center of the thermal. Learn the hysteresis of your instruments - maybe you need to phase-shift your reaction so you really land in the center of the thermal. For me, I found it easier to remember where the climb speed was best and to shift my next circle in that direction when flying two-seaters - they are too sluggish to do that on-the-fly optimization you can do with the more nimble single seaters.
$endgroup$
add a comment |
$begingroup$
If there are cumulus clouds, you hunt for the thermals feeding them on the upwind side. Once you locate one, you "map" its location in your mind by circling and noting which quadrants have the strongest climb and which have sink, shifting your circle toward where you think the core of the thermal is by straightening out momentarily. You are in the sweet spot when you have a decent climb rate all the way around. You fly just above the stall in the thermal, roughly at minimum sink speed.
If the air is too dry so there are no clouds to mark thermal tops, you have to troll for them.
If there are soaring birds or other gliders circling, well, it's obvious.
$endgroup$
add a comment |
Your Answer
StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "528"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);
else
createEditor();
);
function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
noCode: true, onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);
);
Wojciech Kacprzyński is a new contributor. Be nice, and check out our Code of Conduct.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2faviation.stackexchange.com%2fquestions%2f62444%2fwhat-are-the-best-places-to-gain-the-most-altitude-in-a-glider%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
First, you need practice. Take every opportunity to expand your experience. Theory helps but will never compensate for missing practical experience.
But then you also need to know how thermals form. Let's start low, close to the ground. Two things are important: A chance for the sun to heat the ground (and, consequently, the air above), and an opportunity for that heated air to ascend. Dry ground will heat up better than moist ground, and dark earth better than light sand. If the ground is completely featureless, the air will stay on the ground. So you need to find the trigger which determines where air starts to rise up. Once it does this, more air will be sucked in from the side, and will follow up. That is how a thermal starts.
And that summer gust, which is the horizontal motion of more warm air flowing towards the point where a thermal starts, should indicate to you that now you have a chance to stay up, so now you need to get into your glider. Early in the day the thermals will not go high, so don't be impatient. On the positive side, there are many thermals and a good chance of finding the next one quickly.
Once in the air, look for triggers. One of the easiest is a windward edge of a forest. Warm air is driven towards the forest by the prevailing wind, and the trees will push the air up, kickstarting its ascent. Fly along and a bit leeward of the ringe and you can't miss the thermals there. But even a closed forest is a good source of thermals: The dark trees heat up well and the air between the trees heats up quickly. A small elevation is normally enough to start a thermal. In the mountains, a windward ridge is also an obvious trigger, and it is advisable not to drop below the height of the lowest ridge, as you suddenly might find yourself unable to find any more thermals.
Once higher up the ground features become more and more unimportant. For one, wind is shifting everything sideways, but also now the large-scale vorticity which forms the clouds dominates where the thermals form. Think of cumulus clouds as giant thermal vacuum cleaners which collect the rising air from all around. But not any cumulus cloud: Most promising are the ones which grow, have sharply defined edges and a dark bottom which is bulged upwards towards the center. Flee from the fuzzy ones with a round bottom: They have lost their pulling power and are about to disappear.
Why the bulged-in bottom? THAT is where the heated air goes up and pushes the bottom of the cloud up. But what goes up must come down: In the vicinity of the best clouds you will also find the worst downdrafts. Fly through those quickly and pull up as soon as the downdraft stops.
If you fly cross-country, the most important knowledge is in which direction the wind is blowing. If the wind is strong enough (more than a soft breeze), thermals will line up in wind direction, so you can just leave one straight into the wind (or with the wind) and be sure to hit the next one shortly. This works particularly well if there are no clouds to follow (blue thermals). Just remember where exactly that one-before-last thermal was and fly off in exactly the opposite direction. When that brings you too far off the planned course, cross the valley of downdrafts orthogonal to the wind direction until you arrive in the next lineup of thermals.
Now to how to circle properly. A glider will fly at its minimum sink speed when induced drag is three quarters of total drag - given the high aspect ratio of gliders this means at a really high lift coefficient. Close to stall. Therefore, it is most important to learn how the glider warns you that you are about to stall. Also, some gliders will happily let you fly in a stalled condition (the Discus is a prime example) with really poor sink speed but without loss of control. Go up to maybe 1000 m and then stall the glider slowly. Learn how that feels. Then continue with circles. Stall the glider again. At some point you will feel how the stick forces lighten (that is when flow separation starts on the ailerons!) and you will learn to fly just a bit faster than that. Similarly, the stalled Discus has really soft and mushy controls - fly faster until the controls feel stiff again!
Since circling with more than 45° of bank is rather stressful, fly between 30° and 45° of bank angle. You need to catch the core of the thermal, where the climb speed is highest, and banking more is worth the tradeoff in many cases. Tighten the circle when the climb speed decreases and widen it when speed increases - that helps you to center your circling with the center of the thermal. Learn the hysteresis of your instruments - maybe you need to phase-shift your reaction so you really land in the center of the thermal. For me, I found it easier to remember where the climb speed was best and to shift my next circle in that direction when flying two-seaters - they are too sluggish to do that on-the-fly optimization you can do with the more nimble single seaters.
$endgroup$
add a comment |
$begingroup$
First, you need practice. Take every opportunity to expand your experience. Theory helps but will never compensate for missing practical experience.
But then you also need to know how thermals form. Let's start low, close to the ground. Two things are important: A chance for the sun to heat the ground (and, consequently, the air above), and an opportunity for that heated air to ascend. Dry ground will heat up better than moist ground, and dark earth better than light sand. If the ground is completely featureless, the air will stay on the ground. So you need to find the trigger which determines where air starts to rise up. Once it does this, more air will be sucked in from the side, and will follow up. That is how a thermal starts.
And that summer gust, which is the horizontal motion of more warm air flowing towards the point where a thermal starts, should indicate to you that now you have a chance to stay up, so now you need to get into your glider. Early in the day the thermals will not go high, so don't be impatient. On the positive side, there are many thermals and a good chance of finding the next one quickly.
Once in the air, look for triggers. One of the easiest is a windward edge of a forest. Warm air is driven towards the forest by the prevailing wind, and the trees will push the air up, kickstarting its ascent. Fly along and a bit leeward of the ringe and you can't miss the thermals there. But even a closed forest is a good source of thermals: The dark trees heat up well and the air between the trees heats up quickly. A small elevation is normally enough to start a thermal. In the mountains, a windward ridge is also an obvious trigger, and it is advisable not to drop below the height of the lowest ridge, as you suddenly might find yourself unable to find any more thermals.
Once higher up the ground features become more and more unimportant. For one, wind is shifting everything sideways, but also now the large-scale vorticity which forms the clouds dominates where the thermals form. Think of cumulus clouds as giant thermal vacuum cleaners which collect the rising air from all around. But not any cumulus cloud: Most promising are the ones which grow, have sharply defined edges and a dark bottom which is bulged upwards towards the center. Flee from the fuzzy ones with a round bottom: They have lost their pulling power and are about to disappear.
Why the bulged-in bottom? THAT is where the heated air goes up and pushes the bottom of the cloud up. But what goes up must come down: In the vicinity of the best clouds you will also find the worst downdrafts. Fly through those quickly and pull up as soon as the downdraft stops.
If you fly cross-country, the most important knowledge is in which direction the wind is blowing. If the wind is strong enough (more than a soft breeze), thermals will line up in wind direction, so you can just leave one straight into the wind (or with the wind) and be sure to hit the next one shortly. This works particularly well if there are no clouds to follow (blue thermals). Just remember where exactly that one-before-last thermal was and fly off in exactly the opposite direction. When that brings you too far off the planned course, cross the valley of downdrafts orthogonal to the wind direction until you arrive in the next lineup of thermals.
Now to how to circle properly. A glider will fly at its minimum sink speed when induced drag is three quarters of total drag - given the high aspect ratio of gliders this means at a really high lift coefficient. Close to stall. Therefore, it is most important to learn how the glider warns you that you are about to stall. Also, some gliders will happily let you fly in a stalled condition (the Discus is a prime example) with really poor sink speed but without loss of control. Go up to maybe 1000 m and then stall the glider slowly. Learn how that feels. Then continue with circles. Stall the glider again. At some point you will feel how the stick forces lighten (that is when flow separation starts on the ailerons!) and you will learn to fly just a bit faster than that. Similarly, the stalled Discus has really soft and mushy controls - fly faster until the controls feel stiff again!
Since circling with more than 45° of bank is rather stressful, fly between 30° and 45° of bank angle. You need to catch the core of the thermal, where the climb speed is highest, and banking more is worth the tradeoff in many cases. Tighten the circle when the climb speed decreases and widen it when speed increases - that helps you to center your circling with the center of the thermal. Learn the hysteresis of your instruments - maybe you need to phase-shift your reaction so you really land in the center of the thermal. For me, I found it easier to remember where the climb speed was best and to shift my next circle in that direction when flying two-seaters - they are too sluggish to do that on-the-fly optimization you can do with the more nimble single seaters.
$endgroup$
add a comment |
$begingroup$
First, you need practice. Take every opportunity to expand your experience. Theory helps but will never compensate for missing practical experience.
But then you also need to know how thermals form. Let's start low, close to the ground. Two things are important: A chance for the sun to heat the ground (and, consequently, the air above), and an opportunity for that heated air to ascend. Dry ground will heat up better than moist ground, and dark earth better than light sand. If the ground is completely featureless, the air will stay on the ground. So you need to find the trigger which determines where air starts to rise up. Once it does this, more air will be sucked in from the side, and will follow up. That is how a thermal starts.
And that summer gust, which is the horizontal motion of more warm air flowing towards the point where a thermal starts, should indicate to you that now you have a chance to stay up, so now you need to get into your glider. Early in the day the thermals will not go high, so don't be impatient. On the positive side, there are many thermals and a good chance of finding the next one quickly.
Once in the air, look for triggers. One of the easiest is a windward edge of a forest. Warm air is driven towards the forest by the prevailing wind, and the trees will push the air up, kickstarting its ascent. Fly along and a bit leeward of the ringe and you can't miss the thermals there. But even a closed forest is a good source of thermals: The dark trees heat up well and the air between the trees heats up quickly. A small elevation is normally enough to start a thermal. In the mountains, a windward ridge is also an obvious trigger, and it is advisable not to drop below the height of the lowest ridge, as you suddenly might find yourself unable to find any more thermals.
Once higher up the ground features become more and more unimportant. For one, wind is shifting everything sideways, but also now the large-scale vorticity which forms the clouds dominates where the thermals form. Think of cumulus clouds as giant thermal vacuum cleaners which collect the rising air from all around. But not any cumulus cloud: Most promising are the ones which grow, have sharply defined edges and a dark bottom which is bulged upwards towards the center. Flee from the fuzzy ones with a round bottom: They have lost their pulling power and are about to disappear.
Why the bulged-in bottom? THAT is where the heated air goes up and pushes the bottom of the cloud up. But what goes up must come down: In the vicinity of the best clouds you will also find the worst downdrafts. Fly through those quickly and pull up as soon as the downdraft stops.
If you fly cross-country, the most important knowledge is in which direction the wind is blowing. If the wind is strong enough (more than a soft breeze), thermals will line up in wind direction, so you can just leave one straight into the wind (or with the wind) and be sure to hit the next one shortly. This works particularly well if there are no clouds to follow (blue thermals). Just remember where exactly that one-before-last thermal was and fly off in exactly the opposite direction. When that brings you too far off the planned course, cross the valley of downdrafts orthogonal to the wind direction until you arrive in the next lineup of thermals.
Now to how to circle properly. A glider will fly at its minimum sink speed when induced drag is three quarters of total drag - given the high aspect ratio of gliders this means at a really high lift coefficient. Close to stall. Therefore, it is most important to learn how the glider warns you that you are about to stall. Also, some gliders will happily let you fly in a stalled condition (the Discus is a prime example) with really poor sink speed but without loss of control. Go up to maybe 1000 m and then stall the glider slowly. Learn how that feels. Then continue with circles. Stall the glider again. At some point you will feel how the stick forces lighten (that is when flow separation starts on the ailerons!) and you will learn to fly just a bit faster than that. Similarly, the stalled Discus has really soft and mushy controls - fly faster until the controls feel stiff again!
Since circling with more than 45° of bank is rather stressful, fly between 30° and 45° of bank angle. You need to catch the core of the thermal, where the climb speed is highest, and banking more is worth the tradeoff in many cases. Tighten the circle when the climb speed decreases and widen it when speed increases - that helps you to center your circling with the center of the thermal. Learn the hysteresis of your instruments - maybe you need to phase-shift your reaction so you really land in the center of the thermal. For me, I found it easier to remember where the climb speed was best and to shift my next circle in that direction when flying two-seaters - they are too sluggish to do that on-the-fly optimization you can do with the more nimble single seaters.
$endgroup$
First, you need practice. Take every opportunity to expand your experience. Theory helps but will never compensate for missing practical experience.
But then you also need to know how thermals form. Let's start low, close to the ground. Two things are important: A chance for the sun to heat the ground (and, consequently, the air above), and an opportunity for that heated air to ascend. Dry ground will heat up better than moist ground, and dark earth better than light sand. If the ground is completely featureless, the air will stay on the ground. So you need to find the trigger which determines where air starts to rise up. Once it does this, more air will be sucked in from the side, and will follow up. That is how a thermal starts.
And that summer gust, which is the horizontal motion of more warm air flowing towards the point where a thermal starts, should indicate to you that now you have a chance to stay up, so now you need to get into your glider. Early in the day the thermals will not go high, so don't be impatient. On the positive side, there are many thermals and a good chance of finding the next one quickly.
Once in the air, look for triggers. One of the easiest is a windward edge of a forest. Warm air is driven towards the forest by the prevailing wind, and the trees will push the air up, kickstarting its ascent. Fly along and a bit leeward of the ringe and you can't miss the thermals there. But even a closed forest is a good source of thermals: The dark trees heat up well and the air between the trees heats up quickly. A small elevation is normally enough to start a thermal. In the mountains, a windward ridge is also an obvious trigger, and it is advisable not to drop below the height of the lowest ridge, as you suddenly might find yourself unable to find any more thermals.
Once higher up the ground features become more and more unimportant. For one, wind is shifting everything sideways, but also now the large-scale vorticity which forms the clouds dominates where the thermals form. Think of cumulus clouds as giant thermal vacuum cleaners which collect the rising air from all around. But not any cumulus cloud: Most promising are the ones which grow, have sharply defined edges and a dark bottom which is bulged upwards towards the center. Flee from the fuzzy ones with a round bottom: They have lost their pulling power and are about to disappear.
Why the bulged-in bottom? THAT is where the heated air goes up and pushes the bottom of the cloud up. But what goes up must come down: In the vicinity of the best clouds you will also find the worst downdrafts. Fly through those quickly and pull up as soon as the downdraft stops.
If you fly cross-country, the most important knowledge is in which direction the wind is blowing. If the wind is strong enough (more than a soft breeze), thermals will line up in wind direction, so you can just leave one straight into the wind (or with the wind) and be sure to hit the next one shortly. This works particularly well if there are no clouds to follow (blue thermals). Just remember where exactly that one-before-last thermal was and fly off in exactly the opposite direction. When that brings you too far off the planned course, cross the valley of downdrafts orthogonal to the wind direction until you arrive in the next lineup of thermals.
Now to how to circle properly. A glider will fly at its minimum sink speed when induced drag is three quarters of total drag - given the high aspect ratio of gliders this means at a really high lift coefficient. Close to stall. Therefore, it is most important to learn how the glider warns you that you are about to stall. Also, some gliders will happily let you fly in a stalled condition (the Discus is a prime example) with really poor sink speed but without loss of control. Go up to maybe 1000 m and then stall the glider slowly. Learn how that feels. Then continue with circles. Stall the glider again. At some point you will feel how the stick forces lighten (that is when flow separation starts on the ailerons!) and you will learn to fly just a bit faster than that. Similarly, the stalled Discus has really soft and mushy controls - fly faster until the controls feel stiff again!
Since circling with more than 45° of bank is rather stressful, fly between 30° and 45° of bank angle. You need to catch the core of the thermal, where the climb speed is highest, and banking more is worth the tradeoff in many cases. Tighten the circle when the climb speed decreases and widen it when speed increases - that helps you to center your circling with the center of the thermal. Learn the hysteresis of your instruments - maybe you need to phase-shift your reaction so you really land in the center of the thermal. For me, I found it easier to remember where the climb speed was best and to shift my next circle in that direction when flying two-seaters - they are too sluggish to do that on-the-fly optimization you can do with the more nimble single seaters.
edited 19 mins ago
answered 26 mins ago
Peter KämpfPeter Kämpf
162k12412658
162k12412658
add a comment |
add a comment |
$begingroup$
If there are cumulus clouds, you hunt for the thermals feeding them on the upwind side. Once you locate one, you "map" its location in your mind by circling and noting which quadrants have the strongest climb and which have sink, shifting your circle toward where you think the core of the thermal is by straightening out momentarily. You are in the sweet spot when you have a decent climb rate all the way around. You fly just above the stall in the thermal, roughly at minimum sink speed.
If the air is too dry so there are no clouds to mark thermal tops, you have to troll for them.
If there are soaring birds or other gliders circling, well, it's obvious.
$endgroup$
add a comment |
$begingroup$
If there are cumulus clouds, you hunt for the thermals feeding them on the upwind side. Once you locate one, you "map" its location in your mind by circling and noting which quadrants have the strongest climb and which have sink, shifting your circle toward where you think the core of the thermal is by straightening out momentarily. You are in the sweet spot when you have a decent climb rate all the way around. You fly just above the stall in the thermal, roughly at minimum sink speed.
If the air is too dry so there are no clouds to mark thermal tops, you have to troll for them.
If there are soaring birds or other gliders circling, well, it's obvious.
$endgroup$
add a comment |
$begingroup$
If there are cumulus clouds, you hunt for the thermals feeding them on the upwind side. Once you locate one, you "map" its location in your mind by circling and noting which quadrants have the strongest climb and which have sink, shifting your circle toward where you think the core of the thermal is by straightening out momentarily. You are in the sweet spot when you have a decent climb rate all the way around. You fly just above the stall in the thermal, roughly at minimum sink speed.
If the air is too dry so there are no clouds to mark thermal tops, you have to troll for them.
If there are soaring birds or other gliders circling, well, it's obvious.
$endgroup$
If there are cumulus clouds, you hunt for the thermals feeding them on the upwind side. Once you locate one, you "map" its location in your mind by circling and noting which quadrants have the strongest climb and which have sink, shifting your circle toward where you think the core of the thermal is by straightening out momentarily. You are in the sweet spot when you have a decent climb rate all the way around. You fly just above the stall in the thermal, roughly at minimum sink speed.
If the air is too dry so there are no clouds to mark thermal tops, you have to troll for them.
If there are soaring birds or other gliders circling, well, it's obvious.
answered 2 hours ago
John KJohn K
25.7k13878
25.7k13878
add a comment |
add a comment |
Wojciech Kacprzyński is a new contributor. Be nice, and check out our Code of Conduct.
Wojciech Kacprzyński is a new contributor. Be nice, and check out our Code of Conduct.
Wojciech Kacprzyński is a new contributor. Be nice, and check out our Code of Conduct.
Wojciech Kacprzyński is a new contributor. Be nice, and check out our Code of Conduct.
Thanks for contributing an answer to Aviation Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2faviation.stackexchange.com%2fquestions%2f62444%2fwhat-are-the-best-places-to-gain-the-most-altitude-in-a-glider%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
1
$begingroup$
Follow the birds. Circle where they are circling. Upwind side of a mountain, or a ridge. Large dark areas on the ground. Also check with other glider pilots in your area for good local spots.
$endgroup$
– CrossRoads
5 hours ago
1
$begingroup$
Welcome to aviation.se! Welcome to Stack Overflow! Please take the tour, have a look around, and read through the help center, in particular How do I ask a good question? and What topics can I ask about here?. -- Answeres to your question should be part of your glider pilot training.
$endgroup$
– Timothy Truckle
4 hours ago