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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How far can airplanes glide?
On an another question, an answer said:
You don't need an engine to fly as airplanes are designed to glide without it.
I suspect this heavily depends on the type of the aircraft, so lets assume we ...
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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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Could a big plane glide significant distances, same a ordinary glider (1000 km or about)?
Seems that a usual glider is not limited by its glide descent rate and can fly much more than this. It uses air masses that move upward to gain the altitude.
Are these effects limited by the size of ...
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How does the Boeing 787 Dreamliner's glide ratio compare to other airliners?
I just saw a documentary on the design of the Boeing 787 "Dreamliner" and one of the designers said that the wings were inspired by gliders. Looking at the production version of the plane, it is ...
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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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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 is the glide ratio affected when converting a wheeled plane to floats?
I'm looking for published data that describe the effect on glide ratio when an aircraft is converted from wheeled to float configuration. I suspect that the glide ratio goes down considerably due to ...
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How are the glide polar and L/D ratio charts related?
We know from other questions and answers that airplanes and gliders in particular can have their performance described in terms of glide polar and Lift-to-Drag ratio.
As it appears from the images in ...
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What was the Space Shuttle's glide ratio?
The Space Shuttles glided to a landing in the atmosphere after reentry. They were not good gliders, aerodynamically speaking, so their glide slope angle was rather steep.
What was the glide ratio of ...
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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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With existing tech and knowledge of meteorology, can aircraft be designed to reliably improve their range or loiter using updrafts to gain altitude?
Just what the question says. I want to know if aircrafts' range, loiter time, or other measures of merit can be dramatically and reliably increased using our current understanding of meteorology and ...
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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 ...
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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 ...
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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 ...
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During an engine failure should I deploy 10° of flap or keep it clean?
Imagine I have an engine failure in cruise flight with a Cessna 152 or 172.
Should I select 10° flap to increase glide angle?
Would it give me more range to reach safety?
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Where can I find (or how can I calculate) the glide ratio for a PA-28-181?
I'm filling out ForeFlight's new glide slope feature, and I'm trying to find the glide ratio for a Piper Archer II (PA-28-181). I know the best glide speed is 76, but can't find the glide ratio. Any ...
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How can the glide ratio in a balanced turn be estimated?
I am trying to estimate the bank angle/turn radius required to lose a given amount of altitude during a full orbit. This has led me to trying to estimate glide ratio in proportion to $L/D_{MAX}$ of an ...
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How can planes with the same stall speed and power-to-weight ratio have such different takeoff field length, climb rate, glide ratio, etc?
I am interested in better understanding the performance differences between different planes that seem to be similar in many important ways but that differ greatly in performance.
For example, take ...
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Where can I find glide ratios for commercial aircraft?
I know that light aircraft have poor glide ratios (typically 1:10) compared to commercial aircraft (typically 1:20 or above). I was wondering if there is a source where one can find the glide ratio by ...
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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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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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What is a mushing glide?
Source: Wolfgang Langewiesche - Stick and Rudder; An Explanation of the Art of Flying
Why is it called a mushing glide?
In this glide, does the aircraft point its nose less (or more?) steeply?
How ...
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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 to calculate the Glide Ratio from Drag & Lift?
I know that $c_{d}=0.03 + 0.095c_{l}^2$.
What is the glide ratio?
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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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Can glide ratio be increased with bi-wing configuration?
We all know that increasing the wingspan of an aircraft tends to increase the glide ratio. Instead of increasing the wingspan, could an extra wing of the same size or less as in a bi-wing ...
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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 full nose up trim yield best glide in Cessna 172/152 for a given load?
I heard from a ground instructor that full nose up trim will yield best glide in a 152 and 172.
As I understand best L/D, a lighter loaded plane will require a slower glide than the same craft ...
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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 ...
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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, ...
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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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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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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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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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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 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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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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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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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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Is V(L/D)max equivalent to best glide speed regardless of weight, engine, height, etc.?
I've read Carson's paper on V(L/D)max, and while theoretically interesting, it does not seem to me to be useful in actually finding the V(L/D)max of an arbitrary aircraft, as it assumes knowledge of ...
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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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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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Could a commercial plane like Airbus A320 glide with no working engines from 11000 meters? [duplicate]
I have heard that pilots learn in simulators to fly also commercial planes without working engines, so that they glide. And still I have the impression, the chances that a plane could float from 11000 ...
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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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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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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 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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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 ...
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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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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 ...
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