Best Single Engine Glider?
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Best Single Engine Glider?
Hi again chaps and ladies ...
Haven't started my PPL yet due to work commitments
but keep myself entertained by reading this forum and aviation books in the meantime.
I love the idea of flying (As my tial lesson was great), but safety is also important to me and I can't help but to notice the number of people on this forum who experienced engine failures.
Going through some of these threads one guy called Chuck .. had about 6 or 7 instances where the engine had to be switched off and forced landings were made.
I realise that forced landings is something that should be practiced lots so that you know what to do when it happens for real and not freak out. But from reading some of these posts ..... if you fly a lot and you fly for many years it seems like there is a pretty good chance that you will experience this at some stage ... or is this not quite the case? I have to admit the thought of it is slightly off putting.
Secondly ... some of you that do these north trans atlantic flights ... is it pretty much a case of just biting the bullet and hope for the best when you're over water? Again knowing that engine failures are "fairly common" would probably make me think twice?
Then, I know that you pretty much have one chance to make a good landing in case you experience an engine failure, which brings me on to my last question: Which single engine aeroplane would be rated as having the best "gliding" potential ... would it be a little cessna 152 or rather something like a pa28? Do high wings glide better?.. or do they all pretty much come down like rocks.
Sorry if some of these questions seem daft but your comments would be great thanks!
PS - I know that there are other threads about engine failures, spinning props and how to make the best landing, hence some slightly different questions above. Thx
Haven't started my PPL yet due to work commitments
but keep myself entertained by reading this forum and aviation books in the meantime.I love the idea of flying (As my tial lesson was great), but safety is also important to me and I can't help but to notice the number of people on this forum who experienced engine failures.
Going through some of these threads one guy called Chuck .. had about 6 or 7 instances where the engine had to be switched off and forced landings were made.
I realise that forced landings is something that should be practiced lots so that you know what to do when it happens for real and not freak out. But from reading some of these posts ..... if you fly a lot and you fly for many years it seems like there is a pretty good chance that you will experience this at some stage ... or is this not quite the case? I have to admit the thought of it is slightly off putting.
Secondly ... some of you that do these north trans atlantic flights ... is it pretty much a case of just biting the bullet and hope for the best when you're over water? Again knowing that engine failures are "fairly common" would probably make me think twice?
Then, I know that you pretty much have one chance to make a good landing in case you experience an engine failure, which brings me on to my last question: Which single engine aeroplane would be rated as having the best "gliding" potential ... would it be a little cessna 152 or rather something like a pa28? Do high wings glide better?.. or do they all pretty much come down like rocks.
Sorry if some of these questions seem daft but your comments would be great thanks!
PS - I know that there are other threads about engine failures, spinning props and how to make the best landing, hence some slightly different questions above. Thx
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All aeroplanes will glide, obviously some better than others. However, engine failures are actually quite rare and when they do happen, they can usually be linked to some failure on the part of the pilot or aircraft's maintanence (usually fuel starvation or carb icing) How well the aircraft "glides" has less to do with it's ability to arrive back on terra-firma safely than it's stall speed, mass and landing distance. I believe a Boeing 747 actually has a pretty good glide angle ... but I'd not want to dead stick one if the engines failed! A typical microlight though, glides like a brick, but can be put down safely in a space not much bigger than a garden!
I've had one engine failure but just scraped into a small airfield. It was my fault as I was new to the type and ran it out of fuel even though it wasn't empty
SS
I've had one engine failure but just scraped into a small airfield. It was my fault as I was new to the type and ran it out of fuel even though it wasn't empty
SS
It depends what you fly. Whilst it is best practice to assume that if you are in a single engined aeroplane, the engine will fail at some random point on the current or next flight, the reality is that the majority of modern light aircraft engines are extremely reliable and most pilots will never experience an engine failure. (I'll admit to several including a couple of field landings, but much of my flying has been with uncertified engines and a fair bit of that test flying new homebuilts).
Unless an aeroplane has good enough glide capability to thermal, then a good glide ratio will only extend your options, you'll still be coming down eventually (and that's even true in a glider, albeit possibly much later). However, if you are looking for very good glide performance from a single engined aeroplane then the best will certainly be from a motorglider such as a G109b (or a microlight/motorglider hybrid such as a Chevvron). After that, it's likely to be the modern composite aeroplanes that are best such as the Diamond DA40 or the Europa.
For water crossings "hoping for the best" is not the best approach - it's more a combination of confirming likely engine reliability, carrying appropriate safety equipment, planning a route which minimises time over water and maximises rescue opportunities. For flights over mountains, the same applies - to be honest I'd rather have an engine failure low over the English Channel than low over the middle of Snowdonia.
G
Unless an aeroplane has good enough glide capability to thermal, then a good glide ratio will only extend your options, you'll still be coming down eventually (and that's even true in a glider, albeit possibly much later). However, if you are looking for very good glide performance from a single engined aeroplane then the best will certainly be from a motorglider such as a G109b (or a microlight/motorglider hybrid such as a Chevvron). After that, it's likely to be the modern composite aeroplanes that are best such as the Diamond DA40 or the Europa.
For water crossings "hoping for the best" is not the best approach - it's more a combination of confirming likely engine reliability, carrying appropriate safety equipment, planning a route which minimises time over water and maximises rescue opportunities. For flights over mountains, the same applies - to be honest I'd rather have an engine failure low over the English Channel than low over the middle of Snowdonia.
G
Don't have any of these engine related problems with a glider! So much to go wrong in an aeroplane with an engine.........I jest really!
But if you have not started your PPL yet why not start with a few gliding lessons to get a taste for engineless flight. You might even like it, and what's more it will give you skills that can only enhance your PPL training.
Remember in a glider you only get one chance of a landing
But if you have not started your PPL yet why not start with a few gliding lessons to get a taste for engineless flight. You might even like it, and what's more it will give you skills that can only enhance your PPL training.
Remember in a glider you only get one chance of a landing
Vabsie,
Welcome to the wide world of aviation.
Most light airplanes have a glide ration which approximates about a 6:1 ratio or so, though some as little as 3:1...for every foot the aircraft descends, it glides forward three to six feet. Some better, some worse, but that's about the average. That said, the distance one can glide forward isn't particularly important. What's important is being able to land once you get done with the glide.
I've experienced a number of engine failures over the years in single and multi engine aircraft. Only one has resulted in any damage, and that occured at low level in mountainous terrain in the middle of a forest fire. The damage was minor, and I was flying the same airplane a month later after thorough inspections and some light repairs. That particular airplane had a relatively inefficient glide ratio, but the distance wasn't the issue; it was the landing, which was made on rough ground on a hillside. It ended well; I walked away.
Remember that the airplane flies with or without the engine; you don't fly the engine, you fly the wing. Excess thrust, or power, determines the ability of the airplane to climb...but not to land. Only you can do that.
Your safety depends largely on how you plan and conduct your flight. Remaining over and within distance of suitable forced landing sites, for example, is an important part of operating the airplane safely; always know where you can go and have a plan to get there, no matter what the altitude.
I've spent a lot of time in single engine airplanes in places that aren't conducive to a forced landing; inside the Grand Canyon, for example, where very few long, flat spaces are available to set down in the event of an engine failure. I did nearly all my flying there in single engine piston airplanes, often down inside the canyon, often landing on dirt runways and operating in box canyons in rocky, sheer terrain.
In such cases, glide ratio and the best glider was never an issue. The ability to put the airplane down was, and it did happen from time to time to individuals who experienced mechanical failues, fuel issues, weather, conditions that no longer permitted flight (extremely strong downdrafts, etc) and so forth. I experienced one engine failure in there during my time. What I did do was ensure that while a long flat smooth surface might not be available, I could always make a controlled forced landing if the need would arise; down river, on a sandbar, in the water, into trees, etc. I used local wind currents (such as strong updrafts on the downwind side of the canyon) to my benifit and planned my flight through terrain to take advantage of both the terrain and the conditions to give me the best opportunities in the event such a situation would arise.
Most importantly one must always recognize the concept that an engine failure is never a matter of if, but when. It's a mechanical object, just like the airplane, and mechanical objects break. I never make a takeoff without planning for an engine failure. In comparison to the number of takeoffs I've made, the number of engine failures is a very small percentage...very, very small. But it does happen, it has happened, and I always plan on it, however remote the possibility may be.
A fairly recent event in the news was a 747 which experienced multiple engine failures or power loss shortly after takeoff from a mountain field at night, and executed a very dramatic, though argueably successful, forced landing off field. The aircraft was completely destroyd, except for the flight deck, in which eight crewmembers survived. The point there is that while the airplane didn't have what one might call a favorable glide ratio, and certainly isn't made for off-field forced landings, one was made...and most importantly, no matter how many engines you may have, you should always plan on losing them. It does happen.
In a light airplane, power loss isn't the end of the world. The most common engine failure isn't a complete, catastrophic failure, but a partial-power failure. This may or may not enable you to return to an airport. A failed cylinder, for example, or even a fouled spark plug, slipped magneto, etc...might cause enough shaking and vibration to require shutting the engine down, or may simply enable you to switch the good mag and return home.
Whether the engine runs or doesn't, the airplane still flies, and your only concern is maintaining enough airspeed to maintain control while switching your plans to put the airplane on the ground.
North Atlantic flights in single engine airplanes are gambles, no matter how you slide it.
Welcome to the wide world of aviation.
Most light airplanes have a glide ration which approximates about a 6:1 ratio or so, though some as little as 3:1...for every foot the aircraft descends, it glides forward three to six feet. Some better, some worse, but that's about the average. That said, the distance one can glide forward isn't particularly important. What's important is being able to land once you get done with the glide.
I've experienced a number of engine failures over the years in single and multi engine aircraft. Only one has resulted in any damage, and that occured at low level in mountainous terrain in the middle of a forest fire. The damage was minor, and I was flying the same airplane a month later after thorough inspections and some light repairs. That particular airplane had a relatively inefficient glide ratio, but the distance wasn't the issue; it was the landing, which was made on rough ground on a hillside. It ended well; I walked away.
Remember that the airplane flies with or without the engine; you don't fly the engine, you fly the wing. Excess thrust, or power, determines the ability of the airplane to climb...but not to land. Only you can do that.
Your safety depends largely on how you plan and conduct your flight. Remaining over and within distance of suitable forced landing sites, for example, is an important part of operating the airplane safely; always know where you can go and have a plan to get there, no matter what the altitude.
I've spent a lot of time in single engine airplanes in places that aren't conducive to a forced landing; inside the Grand Canyon, for example, where very few long, flat spaces are available to set down in the event of an engine failure. I did nearly all my flying there in single engine piston airplanes, often down inside the canyon, often landing on dirt runways and operating in box canyons in rocky, sheer terrain.
In such cases, glide ratio and the best glider was never an issue. The ability to put the airplane down was, and it did happen from time to time to individuals who experienced mechanical failues, fuel issues, weather, conditions that no longer permitted flight (extremely strong downdrafts, etc) and so forth. I experienced one engine failure in there during my time. What I did do was ensure that while a long flat smooth surface might not be available, I could always make a controlled forced landing if the need would arise; down river, on a sandbar, in the water, into trees, etc. I used local wind currents (such as strong updrafts on the downwind side of the canyon) to my benifit and planned my flight through terrain to take advantage of both the terrain and the conditions to give me the best opportunities in the event such a situation would arise.
Most importantly one must always recognize the concept that an engine failure is never a matter of if, but when. It's a mechanical object, just like the airplane, and mechanical objects break. I never make a takeoff without planning for an engine failure. In comparison to the number of takeoffs I've made, the number of engine failures is a very small percentage...very, very small. But it does happen, it has happened, and I always plan on it, however remote the possibility may be.
A fairly recent event in the news was a 747 which experienced multiple engine failures or power loss shortly after takeoff from a mountain field at night, and executed a very dramatic, though argueably successful, forced landing off field. The aircraft was completely destroyd, except for the flight deck, in which eight crewmembers survived. The point there is that while the airplane didn't have what one might call a favorable glide ratio, and certainly isn't made for off-field forced landings, one was made...and most importantly, no matter how many engines you may have, you should always plan on losing them. It does happen.
In a light airplane, power loss isn't the end of the world. The most common engine failure isn't a complete, catastrophic failure, but a partial-power failure. This may or may not enable you to return to an airport. A failed cylinder, for example, or even a fouled spark plug, slipped magneto, etc...might cause enough shaking and vibration to require shutting the engine down, or may simply enable you to switch the good mag and return home.
Whether the engine runs or doesn't, the airplane still flies, and your only concern is maintaining enough airspeed to maintain control while switching your plans to put the airplane on the ground.
North Atlantic flights in single engine airplanes are gambles, no matter how you slide it.
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thanks for the replies so far ...gte
Frelon .. someone got me a red-letter day and I'm planning to maybe do a gliding lesson as part of that .... need to call and find out where close to London it can be done.
SNS3Guppy - Very informative and hellpful thanks! It makes me realise that engine failure do not necessarily go hand in hand with kicking the bucket. At the same time, still a bit of a concern that you also experienced a few .... but I appreciate it's because you fly/flew a lot. Just thought in an ideal world it would be nice to fly without all this drama
V
Frelon .. someone got me a red-letter day and I'm planning to maybe do a gliding lesson as part of that .... need to call and find out where close to London it can be done.
SNS3Guppy - Very informative and hellpful thanks! It makes me realise that engine failure do not necessarily go hand in hand with kicking the bucket. At the same time, still a bit of a concern that you also experienced a few .... but I appreciate it's because you fly/flew a lot. Just thought in an ideal world it would be nice to fly without all this drama
V
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I seem to recall the average figure was about 7000 hours per power failure.
In 2000 hours' flying I've had 3 power losses in-flight resulting in 2 successful forced landings and one where power was recovered (mechanical fuel pump failure - boost pump got me home). Probably more than my fare share.
It's part of the design and certification procedure that the higher the likelihood of one of these events, the more the aircraft has to be designed to make them survivable. Principally for single engine aircraft, this means a low stall speed making field landings reasonably possible. It's also an essential part of the training in SEPs that you practise and can safely execute a controlled glide to a suitable forced landing site. Failing to fly the aeroplane and maintain a safe speed and attitude is more likely to result in disaster than hitting obstacles in the landing run. There have been several cases where aircraft have hit trees without causing serious injury because the aircraft was stabilised at a sensible approach speed.
If you look at the fatal accident summaries for SEP aircraft, forced landings don't feature that much.
In 2000 hours' flying I've had 3 power losses in-flight resulting in 2 successful forced landings and one where power was recovered (mechanical fuel pump failure - boost pump got me home). Probably more than my fare share.
It's part of the design and certification procedure that the higher the likelihood of one of these events, the more the aircraft has to be designed to make them survivable. Principally for single engine aircraft, this means a low stall speed making field landings reasonably possible. It's also an essential part of the training in SEPs that you practise and can safely execute a controlled glide to a suitable forced landing site. Failing to fly the aeroplane and maintain a safe speed and attitude is more likely to result in disaster than hitting obstacles in the landing run. There have been several cases where aircraft have hit trees without causing serious injury because the aircraft was stabilised at a sensible approach speed.
If you look at the fatal accident summaries for SEP aircraft, forced landings don't feature that much.
Vabsie,
The most dangerous component in the airplane continues to remain the pilot.
Engine failures can occur from environmental conditions (carburetor ice, for example), misfueling (contaminated fuel, water in the fuel tank, etc), mechanical problems (thrown rod, slipped magneto, failed valve...) or disruptionto airflow (blocked air filter, and so forth). Regardless of the cause, and regardless of the statistical frequency at which they may occur, one always plans for them and takes full advantage when it doesn't happen.
I once experienced a very rapid onset of carburetor ice in a straight-tail Cessna 182 in instrument conditions. The engine ran rough and as I pulled the carburetor heat on, the control broke off in my hand (the wire leading to the carb air box failed). I landed on a gravel strip in a valley after emerging from the base of the clouds. It was a high base, and the landing was uneventful. On another occasion I pushed the power up too quickly when deer ran in front of the J-3 cub I was flying, and the engine promptly quit. I was attempting to go around, but made other plans one the power was gone. That too, was uneventful. On another occasion, I experienced a rough engine and then a failure due to a fuel flow fluctuation condition in a Cessna 207. It was in rough desert mountain terrain, and I was close to the terrain. It happened to occur in an unfavorable spot. Switching tanks, applying boost, and adjusting the throttle and mixture resulted in a quick recovery and an uneventful landing at an airport not long thereafter.
On another occasion in a Cessna 206 a lot of banging and vibration occured when a magneto failed not long after departure. I prepared to land on a road, and in the process switched mags, found that it ran extremely rough on one and very well on the other, and made an uneventful landing at an airport not too far away. On another occasion with a student, the airplane began vibrating hard and shaking, I reduced power and remained over a highway while making my way to an airport. I continued to climb a little as I went, and kept suitable sites to make a forced landing beneath me. I landed at the airport without event. On another occasion with a student, following a simulated power off approach to a runway during training, the student applied power to go around and we did...for about 30 seconds...then the engine ran very rough and then quit. Timely application of carburetor heat restored power and we continued around the pattern.
You can see a pattern. How the event ends is largely under your control, and that's why you're doing your training. It's all part of the preparation to be the pilot in command of your airplane. It seems a scary thought presently, perhaps even daunting. It's not. If your instructor is worth his weight in salt, then by the time you're done, you'll be pleasantly surprised when your your engine doesn't fail, and an engine failure should be a second-nature occurence.
I was behind an Ag Truck as we prepared to go spray a field about 20 years ago. I saw a very bright fireball come out of his airplane as the exhaust blew off, a brief explosion, and he shut down. The damage was minimal, and the cause was a failed magneto. It had disintegrated, in fact. It happened on the ground as he advanced power to move onto the runway. Furtunately it happened then, but he was as fully prepared as I was to deal with it had it happened during the takeoff or any time thereafter. Just as you will be.
Bob Hoover, a well known aerobatic, test, and combat pilot, used to do an airshow routine in a shrike commander. It involved a full aerobatic demonstration on both engines. Then he would shut down one engine and perform the routine, then shut down the second engine and perform it without power. It's a matter of energy management and airmanship, and he did a superb job. The mere fact that he had no power available didn't hinder his ability to control the airplane. In fact, part of his routine was returning the airplane to it's starting point after the power off routine...still without power.
Losing your engine can and does happen, but it's not a dire emergency unless you make it so. After you've been training for a short while, you'll see why. The glide down, and the distance it consumes, is really significant only in allowing you to reach a suitable landing site. The ability to glide a long distance is meaningless and irrelevant, if you always keep an engine failure in mind, act accordingly, and keep a suitable landing site nearby. Do that, and you needn't fear.
There are few things more pleasurable than flight in a light single engine airplane. Enjoy every moment of it. Should the occasion arise when you have an opportunity to to exercise some of the abnormal or "emergency" skills you'll learn, be grateful for the experience and savor it. Such occasions don't come along often, and can't be bought with money. Fly safe.
The most dangerous component in the airplane continues to remain the pilot.
Engine failures can occur from environmental conditions (carburetor ice, for example), misfueling (contaminated fuel, water in the fuel tank, etc), mechanical problems (thrown rod, slipped magneto, failed valve...) or disruptionto airflow (blocked air filter, and so forth). Regardless of the cause, and regardless of the statistical frequency at which they may occur, one always plans for them and takes full advantage when it doesn't happen.
I once experienced a very rapid onset of carburetor ice in a straight-tail Cessna 182 in instrument conditions. The engine ran rough and as I pulled the carburetor heat on, the control broke off in my hand (the wire leading to the carb air box failed). I landed on a gravel strip in a valley after emerging from the base of the clouds. It was a high base, and the landing was uneventful. On another occasion I pushed the power up too quickly when deer ran in front of the J-3 cub I was flying, and the engine promptly quit. I was attempting to go around, but made other plans one the power was gone. That too, was uneventful. On another occasion, I experienced a rough engine and then a failure due to a fuel flow fluctuation condition in a Cessna 207. It was in rough desert mountain terrain, and I was close to the terrain. It happened to occur in an unfavorable spot. Switching tanks, applying boost, and adjusting the throttle and mixture resulted in a quick recovery and an uneventful landing at an airport not long thereafter.
On another occasion in a Cessna 206 a lot of banging and vibration occured when a magneto failed not long after departure. I prepared to land on a road, and in the process switched mags, found that it ran extremely rough on one and very well on the other, and made an uneventful landing at an airport not too far away. On another occasion with a student, the airplane began vibrating hard and shaking, I reduced power and remained over a highway while making my way to an airport. I continued to climb a little as I went, and kept suitable sites to make a forced landing beneath me. I landed at the airport without event. On another occasion with a student, following a simulated power off approach to a runway during training, the student applied power to go around and we did...for about 30 seconds...then the engine ran very rough and then quit. Timely application of carburetor heat restored power and we continued around the pattern.
You can see a pattern. How the event ends is largely under your control, and that's why you're doing your training. It's all part of the preparation to be the pilot in command of your airplane. It seems a scary thought presently, perhaps even daunting. It's not. If your instructor is worth his weight in salt, then by the time you're done, you'll be pleasantly surprised when your your engine doesn't fail, and an engine failure should be a second-nature occurence.
I was behind an Ag Truck as we prepared to go spray a field about 20 years ago. I saw a very bright fireball come out of his airplane as the exhaust blew off, a brief explosion, and he shut down. The damage was minimal, and the cause was a failed magneto. It had disintegrated, in fact. It happened on the ground as he advanced power to move onto the runway. Furtunately it happened then, but he was as fully prepared as I was to deal with it had it happened during the takeoff or any time thereafter. Just as you will be.
Bob Hoover, a well known aerobatic, test, and combat pilot, used to do an airshow routine in a shrike commander. It involved a full aerobatic demonstration on both engines. Then he would shut down one engine and perform the routine, then shut down the second engine and perform it without power. It's a matter of energy management and airmanship, and he did a superb job. The mere fact that he had no power available didn't hinder his ability to control the airplane. In fact, part of his routine was returning the airplane to it's starting point after the power off routine...still without power.
Losing your engine can and does happen, but it's not a dire emergency unless you make it so. After you've been training for a short while, you'll see why. The glide down, and the distance it consumes, is really significant only in allowing you to reach a suitable landing site. The ability to glide a long distance is meaningless and irrelevant, if you always keep an engine failure in mind, act accordingly, and keep a suitable landing site nearby. Do that, and you needn't fear.
There are few things more pleasurable than flight in a light single engine airplane. Enjoy every moment of it. Should the occasion arise when you have an opportunity to to exercise some of the abnormal or "emergency" skills you'll learn, be grateful for the experience and savor it. Such occasions don't come along often, and can't be bought with money. Fly safe.
In gliders, engine failure is running out of lift (or failure to find and make use of same
) If too far away from the home field, you will be landing elsewhere. You get used to begging for lift while low within reach of a selected field, and if lucky enough to get away may repeat the situation.
A field landing in a glider with a sink rate of 200' / min is a considerably more leisurely affair than in a single engine airplane that is going down at 800' / min.
I suggest that sink rate and the ability to control it with spoilers, sideslip and flaps counts for more than raw glide ratio; however the glide ratio does give you more choice of fields.
The more difficult form of engine failure for gliders is engine failure of the towplane at low level where you have to let go of the rope and miss the towplane, but a student on first solo just managed it: Student Pilot Makes Safe Landing
) If too far away from the home field, you will be landing elsewhere. You get used to begging for lift while low within reach of a selected field, and if lucky enough to get away may repeat the situation.A field landing in a glider with a sink rate of 200' / min is a considerably more leisurely affair than in a single engine airplane that is going down at 800' / min.
I suggest that sink rate and the ability to control it with spoilers, sideslip and flaps counts for more than raw glide ratio; however the glide ratio does give you more choice of fields.
The more difficult form of engine failure for gliders is engine failure of the towplane at low level where you have to let go of the rope and miss the towplane, but a student on first solo just managed it: Student Pilot Makes Safe Landing
I notice in that article that a photo of the Pawnee is shown, and described as the glider that landed in a field (I suppose at that point it technically was...)
Hurrah for journalists!
Hurrah for journalists!
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Bob Hoover, a well known aerobatic, test, and combat pilot, used to do an airshow routine in a shrike commander. It involved a full aerobatic demonstration on both engines. Then he would shut down one engine and perform the routine, then shut down the second engine and perform it without power. It's a matter of energy management and airmanship, and he did a superb job. The mere fact that he had no power available didn't hinder his ability to control the airplane. In fact, part of his routine was returning the airplane to it's starting point after the power off routine...still without power.
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In the 22 years that I fly I did about 3500 flights and did not experience engine failures or other big failures.
I did encounter a few car crashes however, dangerous thing driving a car, beware.
Keeping my fingers crossed.
Bart
I did encounter a few car crashes however, dangerous thing driving a car, beware.
Keeping my fingers crossed.
Bart
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Most light airplanes have a glide ration which approximates about a 6:1 ratio or so, though some as little as 3:1
A Cessna 152 is around 9:1, a Warrior around 11:1. The worst you are likely to get in a "proper aeroplane" (not a microlight) is better than 7:1, and in a retractable you might get twice that if you manage to stop the prop (or have managed a double failure in a twin, and feather the props).
Lift:drag ration is equal to glide ratio. If your best lift:drag ratio was 3:1 you'd never get airborne in, for example, a 1100 kg aircraft with 160 hp.
If you put the following in Google (it sorts out all the units) "160 hp / 75 kt" it tells you that the maximum thrust from perfect transmission of 160 hp at 75 kts is 3,313 N. Maximum lift would be three times this, 9,919 N. The force just to hold up a 1100 kg aircraft is 10,791 N.
Climb rate is a function of excess power, whereas glide ratio is a function of lift against drag as established by angle of attack. The lift to drag ratio varies with the AoA, which generally in light airplanes we establish by establishing an airspeed...a general approximation of AoA, but not a direct indication.
The glide ratio depends, then, on the airspeed we select, as well as the way the airplane is configured, and flown. An airplane flown at 65 knots will have a different glide than an airplane with 10% flaps extended at 65 knots, and different yet from an airplane flown slightly out of rig or out of "coordination" with or without flaps, etc. Further, the glide ratio depends on the energy absorption of the propeller, and the drag thereof; an airplane with a windmilling propeller glides farther and differently than an airplane with a stopped propeller, and different yet from an airplane being operated at a "zero thrust" setting.
Additionally, the two glides may be made with respect to "best" conditions; one will be maximum range, or the farthest glide, the other with minimum sink; decreased glide ratio and distance, but also decreased rate of descent and a longer time to reach the ground...as well as a reduced vertical impact rate if the same glide speed is maintained to impact.
That's incorrect, both regarding lift, and regarding thrust. In particular, one cannot equate the horsepower output of the engine with thrust, especially without specific information regarding propeller (pitch, fixed, constant speed, etc), propeller efficiency, propeller slippage, atmospheric conditions, propeller RPM, torque, airspeed, and so forth. Additionally, the engine never provides "perfect transmission." Further, climb is a function of excess thrust beyond that required to sustain level flight for a given equivilent airspeed and aircraft configuration. Further still, lift is a function of configuration and angle of attack, not engine power or thrust imparted by the propeller to the airstream.
You stipulated a force (in Newtons) which presumably represents the thrust you've calculated required to sustain level flight in a light airplane. Without having addressed the aircraft type, airspeed, weight, and other pertinent conditions, you simply can't throw out a number suggesting how much power is required, because no other information is given. What you have there is wild guesswork. Lift required to sustain flight is the weight of the aircraft plus down load, in a simple model.
You've confused yourself somewhat by attempting to come up with a thrust value in the first place, further by attempting to multiply it by three to equate a theoretical glide ratio (it doesn't work that way), and by introducing thrust into a glide equation in the first place. Moreover, an aircraft which glides 3:1 at L/Dmax doesn't require three times the thrust to fly, or four times the thrust to fly. You're attempting to impose the thrust value you've arbitrarily determined against what you perceive to the the value of the drag (which isn't known, and can't be directly determined strictly based on the glide ratio)...glide ratio is not the same as L/D ratio, and varies disproportionately as L/D is varied with configuration and AoA.
But it sounds good on the surface view.
You are correct, however, in that some airplanes have higher glide ratios than others. The Katana, or some versions, have glide ratios in excess of 14:1. Sailplanes can be very high...60:1. The U-2 wrings out about 28:1. The Cessna 150 and the Concorde both shared about the same number, around 7 to 8:1.
The cessna 150 has a sea level gross power to weight ratio of 1:16...sixteen pounds per one horsepower, though this is rated power and the engine produces substantially less with an increase in altitude, as well as lower propeller efficiency, etc. This isn't particularly relevant when discussing glide ratio, however, as previously discussed.
Again, however, the specific glide ratio for a given airplane under a given set of conditions really isn't important; the space shuttle has a dismal glide ratio, yet manages to hit it's mark each time, and the glide isn't nearly as important as the landing at the end. Additionally, unless one is far from a suitable forced landing site, then maximizing one's glide is really irrelevant, and minimum sink with a decreased glide ratio may become more important to establish communications, attempt an engine re-start, configure the aircraft or personnel on board for a forced landing, etc.
The glide ratio depends, then, on the airspeed we select, as well as the way the airplane is configured, and flown. An airplane flown at 65 knots will have a different glide than an airplane with 10% flaps extended at 65 knots, and different yet from an airplane flown slightly out of rig or out of "coordination" with or without flaps, etc. Further, the glide ratio depends on the energy absorption of the propeller, and the drag thereof; an airplane with a windmilling propeller glides farther and differently than an airplane with a stopped propeller, and different yet from an airplane being operated at a "zero thrust" setting.
Additionally, the two glides may be made with respect to "best" conditions; one will be maximum range, or the farthest glide, the other with minimum sink; decreased glide ratio and distance, but also decreased rate of descent and a longer time to reach the ground...as well as a reduced vertical impact rate if the same glide speed is maintained to impact.
Lift:drag ration is equal to glide ratio. If your best lift:drag ratio was 3:1 you'd never get airborne in, for example, a 1100 kg aircraft with 160 hp.
If you put the following in Google (it sorts out all the units) "160 hp / 75 kt" it tells you that the maximum thrust from perfect transmission of 160 hp at 75 kts is 3,313 N. Maximum lift would be three times this, 9,919 N. The force just to hold up a 1100 kg aircraft is 10,791 N.
If you put the following in Google (it sorts out all the units) "160 hp / 75 kt" it tells you that the maximum thrust from perfect transmission of 160 hp at 75 kts is 3,313 N. Maximum lift would be three times this, 9,919 N. The force just to hold up a 1100 kg aircraft is 10,791 N.
You stipulated a force (in Newtons) which presumably represents the thrust you've calculated required to sustain level flight in a light airplane. Without having addressed the aircraft type, airspeed, weight, and other pertinent conditions, you simply can't throw out a number suggesting how much power is required, because no other information is given. What you have there is wild guesswork. Lift required to sustain flight is the weight of the aircraft plus down load, in a simple model.
You've confused yourself somewhat by attempting to come up with a thrust value in the first place, further by attempting to multiply it by three to equate a theoretical glide ratio (it doesn't work that way), and by introducing thrust into a glide equation in the first place. Moreover, an aircraft which glides 3:1 at L/Dmax doesn't require three times the thrust to fly, or four times the thrust to fly. You're attempting to impose the thrust value you've arbitrarily determined against what you perceive to the the value of the drag (which isn't known, and can't be directly determined strictly based on the glide ratio)...glide ratio is not the same as L/D ratio, and varies disproportionately as L/D is varied with configuration and AoA.
But it sounds good on the surface view.
You are correct, however, in that some airplanes have higher glide ratios than others. The Katana, or some versions, have glide ratios in excess of 14:1. Sailplanes can be very high...60:1. The U-2 wrings out about 28:1. The Cessna 150 and the Concorde both shared about the same number, around 7 to 8:1.
The cessna 150 has a sea level gross power to weight ratio of 1:16...sixteen pounds per one horsepower, though this is rated power and the engine produces substantially less with an increase in altitude, as well as lower propeller efficiency, etc. This isn't particularly relevant when discussing glide ratio, however, as previously discussed.
Again, however, the specific glide ratio for a given airplane under a given set of conditions really isn't important; the space shuttle has a dismal glide ratio, yet manages to hit it's mark each time, and the glide isn't nearly as important as the landing at the end. Additionally, unless one is far from a suitable forced landing site, then maximizing one's glide is really irrelevant, and minimum sink with a decreased glide ratio may become more important to establish communications, attempt an engine re-start, configure the aircraft or personnel on board for a forced landing, etc.
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Your first paragraph is correct, but irrelevant. Yes glide ratio is also a function of speed and configuration. However if we considering best glide ratio which is close to how we fly a glide, so that can be assumed constant for a given design, it is also close to best rate of climb speed.
My thrust calculation is not wrong, unless there have been some fairly radical advances in physics since I took my degree.
It was was never meant to be accurate. Read it again and note that I said "the maximum thrust from perfect transmission" of the power. I was not assuming this would be achieved. Of course there are losses along the way, but as you point out these are not quantifiable. All we can do without further information is say that the thrust is less than a certain figure (it is common in physics to work out the constraints of a problem if you can't work out the exact answer, before making some esimates or experimental adjustments). I proved that the thrust is constrained to less than the figure required just to remain level. I never considered climb, as we certainly can't do so unless we can remain level. I am aware that rate of climb depends on excess power. I am also aware that angle of climb depends on excess thrust. I am also aware that to achieve either you need excess power and thrust.
By the way, I have ignored one or two factors. I know enough about the issue to judge that they make less difference than the inefficiencies in power to thrust transfer, and we are only making a ballpark calculation. If you know enough to challenge them, then we can discuss whether they are valid.
I calculated what lift was required to sustain level flight, not the power. For that the only information needed is the mass and 9.81 N/kg.
I was not confused by trying to calculate the limit to thrust (I wasn't trying to calculate actual thrust, we don't have enough information). It is the only way we can consider constraints to available lift. Power can only achieve lift through thrust.
Multiplying by three was correct. It does work that way. If lift:drag ratio is 3:1 then the weight that can be sustained in level flight is 3 times the thrust. Thrust equals drag in sustained flight, and lift is three times drag. That's what lift:drag ratio means.
I never suggested it needed three times the thrust to fly. Multiplying by three I was working from drag to lift, not the other way round.
Drag can indeed be determined from the glide ratio given a known weight. Glide ratio is identical to lift:drag ratio. In steady flight thrust=drag and lift=weight. Divide weight by glide ratio and you have the exact thrust required to sustain level flight. This always used to be taught in the ATPL theory, and I assume it still is.
Before you post again, I suggest you go into the books. Most of this discussion is beyond what a typical pilot would ever bother to learn. However denying that lift:drag and glide ratio are equal you have made an error that no ATPL student would, at least not one who was likely to pass the exams. It is one of the basic facts in the syllabus (I could prove it if you like, but diagrams are a pain here so I suggest you look it up). I don't expect a PPL to know necessarily, but if you're going to discuss aerodynamics at ATPL level then it's really necessary.
Where did you get the figures 6:1 and 3:1 anyway? As I said, they are not the figures I have found. The 14:1 comes directly from the manual of a retractable. The 7:1 was from the manual of an aircraft with lovely short wings, so poor glide performance (in fact I think it was 7.3:1). The rest come from various sources, less reliable but consistent. And anyway, think about a C152 in the glide, about 800 feet per minute at 70 kts as far as I recall from teaching in them. That's a bit less than 9:1 at a bit over ideal glide. The Warrior has a wing optimised for low speed, so it has a better glide ratio.
You now admit that the Katana has 14:1, not surprising from the sleek shape and long wings. Why would you assume that a typical light aircraft is so much worse as to give 6:1, and a poor one 3:1? I don't think you realise how that would affect performance, as you were unaware of the lift:drag ratio's relationship with glide ratio.
Your first paragraph is correct, but irrelevant. Yes glide ratio is also a function of speed and configuration. However if we considering best glide ratio which is close to how we fly a glide, so that can be assumed constant for a given design, it is also close to best rate of climb speed.
My thrust calculation is not wrong, unless there have been some fairly radical advances in physics since I took my degree.
It was was never meant to be accurate. Read it again and note that I said "the maximum thrust from perfect transmission" of the power. I was not assuming this would be achieved. Of course there are losses along the way, but as you point out these are not quantifiable. All we can do without further information is say that the thrust is less than a certain figure (it is common in physics to work out the constraints of a problem if you can't work out the exact answer, before making some esimates or experimental adjustments). I proved that the thrust is constrained to less than the figure required just to remain level. I never considered climb, as we certainly can't do so unless we can remain level. I am aware that rate of climb depends on excess power. I am also aware that angle of climb depends on excess thrust. I am also aware that to achieve either you need excess power and thrust.
By the way, I have ignored one or two factors. I know enough about the issue to judge that they make less difference than the inefficiencies in power to thrust transfer, and we are only making a ballpark calculation. If you know enough to challenge them, then we can discuss whether they are valid.
I calculated what lift was required to sustain level flight, not the power. For that the only information needed is the mass and 9.81 N/kg.
I was not confused by trying to calculate the limit to thrust (I wasn't trying to calculate actual thrust, we don't have enough information). It is the only way we can consider constraints to available lift. Power can only achieve lift through thrust.
Multiplying by three was correct. It does work that way. If lift:drag ratio is 3:1 then the weight that can be sustained in level flight is 3 times the thrust. Thrust equals drag in sustained flight, and lift is three times drag. That's what lift:drag ratio means.
I never suggested it needed three times the thrust to fly. Multiplying by three I was working from drag to lift, not the other way round.
Drag can indeed be determined from the glide ratio given a known weight. Glide ratio is identical to lift:drag ratio. In steady flight thrust=drag and lift=weight. Divide weight by glide ratio and you have the exact thrust required to sustain level flight. This always used to be taught in the ATPL theory, and I assume it still is.
Before you post again, I suggest you go into the books. Most of this discussion is beyond what a typical pilot would ever bother to learn. However denying that lift:drag and glide ratio are equal you have made an error that no ATPL student would, at least not one who was likely to pass the exams. It is one of the basic facts in the syllabus (I could prove it if you like, but diagrams are a pain here so I suggest you look it up). I don't expect a PPL to know necessarily, but if you're going to discuss aerodynamics at ATPL level then it's really necessary.
Where did you get the figures 6:1 and 3:1 anyway? As I said, they are not the figures I have found. The 14:1 comes directly from the manual of a retractable. The 7:1 was from the manual of an aircraft with lovely short wings, so poor glide performance (in fact I think it was 7.3:1). The rest come from various sources, less reliable but consistent. And anyway, think about a C152 in the glide, about 800 feet per minute at 70 kts as far as I recall from teaching in them. That's a bit less than 9:1 at a bit over ideal glide. The Warrior has a wing optimised for low speed, so it has a better glide ratio.
You now admit that the Katana has 14:1, not surprising from the sleek shape and long wings. Why would you assume that a typical light aircraft is so much worse as to give 6:1, and a poor one 3:1? I don't think you realise how that would affect performance, as you were unaware of the lift:drag ratio's relationship with glide ratio.
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"an airplane with a windmilling propeller glides farther and differently than an airplane with a stopped propeller"
?????...I thought a rotating prop caused more drag than a stationary prop.
BTW, I have zero hours in my log book (I believe your expected to make that clear in here)
?????...I thought a rotating prop caused more drag than a stationary prop.
BTW, I have zero hours in my log book (I believe your expected to make that clear in here)