Questions tagged [glide-ratio]

The ratio of the forward distance traveled to the vertical distance an aircraft descends when gliding without any power.

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Why the heavier the aircraft is, the higher the airspeed must be to obtain the same glide ratio?

I know weight does not affect glide ratio. But why does higher weight need higher gliding speed?
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Does glide ratio improve with increase in scale?

Will the same glider have higher glide ratio if its bigger in proportion or smaller in proportion?
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How to calculate and understand glide distance?

How would I calculate my glide distance? If I am at 8000 feet would I multiply 1.5 by 8 because the ratio is 1.5 NM per thousand ft? Which would be 12 NM Also where did a ratio of 9:5 come from? I may ...
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Size of speed brakes for glider

I have a concept glider and I am trying to calculate the required speed brake area. The clean glide ratio is currently 30, and with speedbrakes, I am aiming at reducing it to something around 7. I ...
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glide ratio of an airplane formula

Good morning everyone, I found out that the glide ratio of an airplane can be calculated by this formula : 1/tan(y) considering y the angle formed by its nose and an horizontal line. Check this photo :...
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Sources for Aircraft Glide Ratio

I would like to gather data on the best glide ratio of different commercial aircraft. Unfortunately, it has proven non-trivial to obtain data aside from a few lucky examples. Eurocontrol's BADA gives $...
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How is half of the wing strut (high wing) [or half the aileron (low wing)] a good reference to estimate gliding distance? [closed]

Through training and still to this day, I keep on using these reference points to judge if I am at the right distance from the runway or the field I aim to land at (forced landing).
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How to accurately test glide ratio in given configuration?

How can glide ratio be accurately measured with typical GA airplane instruments in real conditions? What, if any, specialty instruments are used for professional glide ratio testing (such as a ...
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Can weight reduce a plane's glide ratio?

The FAA says glide ratio doesn't change, regardless of weight, here on page 5-7. Glide ratio is not affected by weight because, while a heavier glider sinks faster, it does so at a greater airspeed. ...
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Calculating best glide speed

I recently started flying a SGS 2-33 glider. The POH lists the stall speed as 31 mph for solo flight. Min sink speed is 38 mph and optimal glide speed is 45 mph. Being an old glider with imperfections,...
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How is a "turning polar" constructed?

To start with something familiar: here's a flight polar. As we learned, the best glide speed is found by starting at the 0,0 point, and drawing a line tangent to the sink rate line. The intersection ...
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How much thrust can a balloon generate with wings?

I have heard that some balloons have been made with wings, angled such that they generate some forward thrust during the ascent. Balloons can also theoretically generate thrust with wings during a ...
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F1A COMPETITION GLIDER

I am working on a school project. I have looked up the airfoil database. There is a wide range of airfoils I have tried to optimize for my glider to no avail. How do i choose the best airfoil for a ...
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How to calculate sink rate from wing measurements

First of all, sorry to bother you when I am coming from a bird rather than aircraft background. I have two questions that I'm struggling to get an answer for. Firstly, how is sink rate calculated (...
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For maximum glide range, should I minimize glide angle or AoA?

I'm currently taking an aeronautical engineering course in school. For an upcoming project, we're going to build balsa toss gliders and we have to design our own wings. The program we're using (Aery32)...
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Under what engine conditions is glide performance typically determined in performance charts?

The performance section of an information manual I am using states that the glide range indicated is "power off". Does this terminology definitely imply that the engine is not firing? or ...
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Does altitude affect glide ratio?

Lower altitude means higher air density, which means more liff, which means a glider can maintain a given glide slope at lower airspeed. As a rule, aircraft tend to have higher peak L/Ds at low ...
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What happens if I am flying at a higher Lift/Drag ratio than required?

I created for me a table from an aircraft for Mach=0.8 for alpha= 0° to 8° Actually, I an alpha of alpha=4° should be sufficient, so that my lift coefficient is enough, to counterbalance the weight in ...
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Relationship between Load-Factor AND Gliding Ratio

I am wondering about the g-load and its relation to the so called gliding ratio. I read this really good contribution here on this forum: Does lift equal weight in a climb? So the g load factor is ...
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What are the engine-out implications of giant turbofans?

It seems that turbofans for civil airliners are improving fuel efficiency by building larger and larger fans that spin slower. For example, the RR Trent 800 introduced in 1993 had a diameter of 2.8m, ...
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How does pitch relate to glide angle?

When flying a glider, you have a polar curve. As your speed increases beyond best glide, your glide angle gets steeper. Say you are flying at best glide, you are looking through a specific point in ...
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What are "secondary precessional forces" that apply to boomerangs in flight?

note: This question is about the aerodynamics of boomerang flight and how it differs in microgravity environments. Some background information available here in Aviation SE: Are frisbees and ...
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Can we show through simple geometry rather than formulae or graphs that the best glide ratio occurs at the maximum ratio of Lift to Drag?

For an unpowered glider, can we show through simple geometry involving force vector diagrams, rather than mathematical formulae or graphs, that the best still-air glide ratio is achieved at the angle-...
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Why are birdlike airfoils not used?

Here are two airfoils (lets focus on Re 100,000): SD7043-il which is simple to build and has a glide ratio of about 60 e376-il a birdlike and much harder to build if using paper or similar due to the ...
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Do jet aircraft have a better glide ratio than propeller aircraft in general? If so, why?

Being fond of aviation, I play with software simulators a lot. I have noticed that while jets seem to be able to glide for a long distance even at zero throttle, propeller aircraft need to be ...
Ritesh Singh's user avatar
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Does Green Dot Speed Calculation include banking Angle?

I'm wondering, whether the Green Dot- speed calculation in the Airbus PFD does account for the actual bank angle of the aircraft. ...
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Why is the L/D ratio numerically equal to the glide ratio?

*L/D is ratio of two forces, lift and drag. *Glide ratio is ratio of two distances. Can you explain mathematically how they end up numerically equal and are they always equal?
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How does retracting flaps help extend the glide of an aircraft?

As per the video from Smithsonian channel BA flight 38's captain retracted the flaps of the Boeing 777 by 5 degrees to extend glide, to travel further. Why?
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Mushing glide vs forward slip sink rate

Source: Wolfgang Langewiesche - Stick and Rudder; An Explanation of the Art of Flying I ran across a mushing glide in Wolfgang Langewiesche's - Stick and Rudder; An Explanation of the Art of Flying ...
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How can a designer maximize the glide ratio of an aircraft with low aspect ratio wings, other than by increasing the aspect ratio?

As I understand it, the gliding range is given by a lift to drag ratio—hence to increase the gliding range, I would want to increase the lift and reduce the drag as much as possible. To that end, ...
singularity's user avatar
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Why don't smaller powered airplanes have better lift-to-drag ratios?

Many airliners have LDRs near 20, and it sounds like the electric Eviation Alice may have an LDR of 24 at 240 kts, but many small planes typically have LDRs of only 8-10. It seems like they could ...
Spencer Ahrens's user avatar
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1 answer
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How to calculate or design glide ratio? [duplicate]

Was interesting to watch the explanation about glider here, especially about the glide ratio. Glide ratio is defined as the ratio between altitude when it start gliding (Y-axis) to the distance it can ...
AirCraft Lover's user avatar
2 votes
1 answer
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How does the glide ratio change with velocity in a glider with air brakes deployed?

I'm interested in how the glide ratio steepens when increasing velocity, starting from the best slope (best L/D) velocity, in a high drag configuration (air brakes fully extended on a glider). I've ...
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Does lift coefficient for maximum range change for a glider experiencing headwind?

When a glider or unpropelled aircraft experiences headwind, I understand that the flight velocity and sink velocity for the "new" maximum possible range both increase (see velocity polar from How does ...
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For how long can an Embraer E195 airplane glide at malfunction?

E195 specs: Maximum Takeoff Weight 52,290 kg Max Cruise Speed M 0.82 Cruise altitude: 35000 feet Assume the weather condition is perfect (no clouds or gust winds). Also assume this airplane is fully ...
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Is the physical MAX8 design bad because software is required for the aircraft to stay airborne? [closed]

I'm not an aviator by any means, but one thing that has come up in recent conversations with friends is that the MAX8 is inherently unsafe because alone, unpowered, the craft is not 'aerodynamically ...
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Aerodynamics and fuel consumption of a powered glider

I want to optimize the flight distance of a powered glider model airplane, without the use of soaring. I've studied some aerodynamics books, but still feel unsure about my conclusions. Please tell me ...
Björn Morén's user avatar
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4 answers
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Descending on a given glide slope (e.g. ILS) at a given airspeed-- is the size of the lift vector different in headwind versus tailwind?

We had a discussion with friend and we were talking about if the airplane is on approach and the one is landing with tailwind and the other one is landing with headwind, so both have the same value of ...
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How useful would the space shuttle OMS actually be in atmosphere?

When speaking of space shuttle landings, they always mention that it is "very poor glider, with one shot, no go-arounds." Of course this is true; however, if the Shuttle found itself in a situation ...
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Best glide speed vs. best glide angle? Maximum glide range?

I have some open questions regarding best glide in a descent: I understood, that there is a best glide speed. This best glide airspeed occurs at the highest lift-to-drag ratio (L/D). This best glide ...
opt12's user avatar
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Why is polar curve of a glider dependent on flight load?

This is my first question here. I'm just a glider in education phase and not yet a pilot, but because I'm also physicist, I'm interested in some details more than other people. My question is simple:...
MichaelW's user avatar
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What is the effect of fuselage weight on a model glider?

I've built a model glider and wanted to see the effect the weight of the fuselage had on its performance. It flew the further with more weight which seems counter intuitive. I can exert more force ...
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8 answers
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Why aren't any wingsuits able to sustain flight?

I'm aware that under zero power it is a glider, but there are gliders that sustain flight and have enough lift to climb etc (Edit: this is not always true. See below answers for why). So, would it not ...
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3 answers
583 views

Are frisbees and boomerangs technically gliders?

Frisbees and Boomerangs are heavier-than-air, unpowered, and fly through the air. So are they technically gliders? They also rotate, so I wonder if these are actually some kind of rotorcraft-type ...
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Does it help to climb in case of a partial engine failure?

When the engines of a airplane show irregularities that do not reduce performance but indicate a possible failure of the engines, is it useful to climb to a higher level, to increase the glide length ...
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How long can a passenger aircraft glide without engine power? [duplicate]

Assuming that the aircraft is cruising at 36000 ft and lost engine power, how long could a passenger aircraft glide?
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What would be the best alternative during a dead-stick approach?

(Disclaimer: I am not a pilot so my understanding of things may be really broken) If a plane has lost engine power, has limited altitude to work with, and is upwind of a landing strip, and the pilot ...
Russell Borogove's user avatar
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0 answers
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What is the glide ratio of a DA42?

I was looking for the best glide speed of a DA42 with both engines out, but it seems it's not in the POH. In the emergency checklist, it only mentions a speed of 85 knots to maintain on final approach ...
Delta's user avatar
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How can we calculate the benefit gained from taping glider wing roots?

Most (all?) glider pilots will be familiar with the practice of taping wing roots. As most of the gliders in my glider club (and I would guess, in the world) are stored with the wings detached, the ...
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How can I calculate the glide time for a B737 with engine failure?

We talked today in our flight school about the following scenario: if I climb in my 737-800 to FL100 and then have a dual engine failure, how many seconds would it take me before I reach ground? I'm ...
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