Questions tagged [efficiency]
Efficiency is the (often measurable) ability to avoid wasting materials, energy, efforts, money, and time in doing something or in producing a desired result. In a more general sense, it is the ability to do things well, successfully, and without waste.
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Which engine is more financially economical to operate, a turboprop or gasoline engine?
I've seen a discussion about this somewhere before. I'm aware that there's no real way to calculate this. So rather then comparing weight and volume for efficiency, let's compare prices. Which engine ...
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Why is a dedicated compressor more efficient than using bleed air to pressurize the cabin?
Bleed air is air "stolen" from the compressor of the jet engine and has traditionally been used to pressurize the cabin. The alternative is to use a separate compressor just to provide cabin ...
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Does Oswald Efficiency make a significant difference on RC-aircraft?
As we know, Oswald Efficiency ($\epsilon$) is caused by change in downwash over the span of the wing, thus causing a change in effective angle of attack over the wing and therefore induced drag ...
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How to calculate boundary layer thickness?
So I have a flat plate with a surface of 7sqm and an aspect ratio of 12 with air blowing straight at it (like a wing) at a speed of 50km/h. I would like to manually calculate the thickness of the ...
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Trailing edge flaps use [duplicate]
Why is it that trailing edge flaps are only used at lower speeds?
Can they be used at higher speeds too?
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Carbon footprint & fuel efficiency vs flight distance
I was looking into my carbon footprint related to flying and seem to have came across somewhat of a contradiction.
WIKIPEDIA says "mid-range is better"
https://en.wikipedia.org/wiki/...
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Why does an aircraft require less power when it is flying slower than the most efficient speed?
While I understand the derivation of Power required,
I fail to understand why minimum power required corresponds to a velocity that is lower than velocity corresponding to minimum thrust required.
My ...
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Examples of jet turbine values for combustions, fuel flow, Q of fuel, temp of exhaust, etc. for classroom use
I am trying to build jet turbine examples for a class and I want to use actual values for the mass flow of fuel and air, combustion temps, exhaust temps, exhaust composition (CO, CO2,H20,o2, NOx) ext…
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What is the optimal jet engine size for maximum range? [closed]
I under stand the flying wing has been calculated to have an optimal length. Is their an optimal blade length within a turbine engine for planes as well?
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Are Foward Swept Wings for a Rear Propeller Airplane Feasible?
Would going with a forward swept wing design, with the same cord and length of the "A Wing", bring more air the the propeller and tail to increase range, power, or stability?
Consider the ...
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What difference does altitude make on fuel efficiency? [duplicate]
Most commercial flights are between 29,000 and 42,000 feet in altitude apparently. But I realise I don't know why. My guesses are:
If you fly too high the air pressure gets very low and you have to ...
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What exactly does "efficiency" mean in XFLR5 wing analysis?
Can somebody please tell me what it is / how is it calculated?
I initially thought it might be something with the Cl/Cd but I have another design with close to the same Cl/Cd, but with more than ...
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Has the use of a radiator surface on the inside of duct ever been tried?
I wonder if using radiating surface on the inside of a ducted fan to dispel the waste heat of an engine would provide an economic advantage by increasing thrust? Since a typical engine “wastes” some ...
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Why are the wheels of aircraft relatively small?
I was wondering why the wheels of aircraft are relatively small compared to for example cars? I could imagine that it is more efficient when traveling to have smaller wheels. The majority of ...
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Will a heavier aircraft be more efficient at high speeds(cruise)? [closed]
Since heavier aircraft have more mass and inertia, they will have less drag because it will be easier for them to push through the air so does that mean that we can achieve the same cruise speed with ...
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Would a Tip Jet be more efficient or practical the bigger/longer it gets?
In summary, a tip jet is a jet nozzle at the tip of some helicopter rotor blades, used to spin the rotor without much torque.
Source of the picture (it is an article)
One of the types of Tip Jet is ...
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Sea-Going Ground-Effect Vehicle
Is a Ground-effect vehicle (a.k.a. ekranoplan) practical in seas near the coast (e.g. the US East Coast, West Coast, and Gulf of Mexico)?
I'm looking for a practicality answer, like, nope, cannot be ...
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Why does adding more blades to a propeller/fan not show a decrease in efficiency?
According to this answer increasing blade solidity increases the blade area by either enlarging chord or increasing blade count both of which reduce efficiency via reducing the lift coefficient and ...
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When using momentum theory for estimating power needed to hover, is propulsive efficiency accounted for?
I am using momentum theory to estimate power needed for an eVTOL. I have read past papers where the results got from momentum theory was direcly use to estimate the power needed from the battery. How ...
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Extrapolating Oswald Efficiency Factor from CL^2 vs CD Graph
I have plotted this CL^2 vs CD graph for a glide test performed in a flight simulator. I want to find the Oswald Efficiency Factor, e from it and I assume I can do that from its gradient. With a wing ...
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Power calculation of propeller
This is probably a very simple question, but I have been really struggling and need your help.
I have simulated a propeller with these parameters on Ansys:
Thrust: 2000 N
Angular Velocity: 314 rad/s
...
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What is the meaning of "Contra-Rotating Propeller Increases Efficiency"? How is it calculated?
This picture is taken from here.
In that video is mentioned that contra-rotating propeller increases efficiency up to 6-16%. Regardless of the number that could be vary from one airplane to another, ...
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Would blade-less (Dyson style) jet engines work? [duplicate]
Is it possible to design an aircraft with blade-less (same concept as Dyson) design to generate thrust?
What are some of the key benefits, drawbacks and examples of attempts (if any) at this kind of ...
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How efficient is a Scramjet?
I searched about the subject, but I couldn't find any place where the overall efficiency of the scramjet is compared to the other types of engines.
All they say is how the "Scramjet is more ...
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Can a Magnus/Coanda effect be used on wings with hot gases for more efficiency? What are current aircrafts that uses such system?
Well, I don't know much about this type of mechanism, and the only post I could find that has something similar to what I'm asking is this one, but isn't quite what I'm asking.
So, the idea would be ...
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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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Are there any aircraft where wing, horizontal empennage and optionally canards produce positive lift?
Planes are more stable if the center of mass is ahead of the center of lift. But this means that the tail must provide downforce to keep the nose up, which is inefficient.
Are there any designs where ...
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Why does the optimum cruise altitude depend on the weight of the airplane?
In this answer, Bianfable notes:
[O]ptimum cruise altitude for a 777-200LR at a weight of 340 t is only FL285, but after burning 100 t of fuel it has increased to FL360
Why is that? Is it simply ...
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Comparison: e-aircraft vs. ground EV modes (car, coach, rail)
I'm looking for (and struggling to find) a comparison for any e-aircraft vs. ground EV modes (car, coach, rail) carrying an equivalent payload, an equivalent distance.
So basically, if you fly from ...
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Why is my calculated seat-miles per gallon of small aircraft higher than of big aircraft?
I've calculated the seat-miles per gallon for three planes. This factors in the speed; it basically means how much does it cost to transport 1 person 1 mile.
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Seats
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gph
seat-mpg
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How does bypass air work?
As far as I’m aware, high-bypass engines have far higher fuel efficiency than low-bypass engines, and as a result the effective specific impulse of the engine is increased. What I’m trying to figure ...
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Why is thrust inverse to speed in piston engines?
It is said that piston engines have constant power output, and thus their thrust is inverse to speed (e.g. here), while turbines have relatively constant thrust. I'm looking for an intuitive ...
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How to calculate the efficiency of a rubber powered propeller
I made a simple test rig together with a stopwatch to measure the thrust (in grams) with respect to time of a rubber powered propeller. This enabled me to compare the performance of different ...
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When, and how to calculate this, you can expect too much Wing Dihedral generates Dutch Roll, increases in Drag? [closed]
The question comes from the Arup designs, and the engineer who turned it into blueprints, Hoffmann, ('A Novel All Wing Airplane', Raoul J Hoffman, Popular Aviation, March 1935, pp 163 and 196), they ...
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What is the function of the aft stator in CFM's open rotor engine design?
CFM revealed their design for a open rotor propfan engine with two stages of blades - one active set of blades rotating in the forward and an static sets of blades on the aft.
According to The ...
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What's the optimal cruise lift to drag ratio of the Piaggio Avanti?
I'm interested in the maximum L/D this plane can achieve. I can't find the necessary data to do the calculation myself.
If I knew the "long range cruise" engine power and assumed 85% ...
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Formula for comparing drag on planes flying at different speeds at different altitudes. Ex: Mach .80 at 40,000 ft, vs Mach 5 at 100,000 ft
I am interested in getting a sense of how much extra energy is needed to overcome drag at different speeds and altitudes. For example, for me a baseline would the drag on an airplane flying something ...
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What factors cause a turbine aircraft to have decreasing fuel burn over time?
Consider a fictional aircraft with a fuel schedule similar to the following:
...
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Why hasn't the US military performed aftermarket modifications on certain aircraft?
The US military emits more CO2 annually than several countries. Winglets have been proven to work well in the commercial sector to reduce fuel burn, therefore reducing both CO2 emissions and fuel cost....
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Why does propeller slip (efficiency) change during the flight (fixed-pitch)?
I was wondering how the efficiency of a fixed-pitch propeller changes during different stages of flight and why it does so. I suppose when we are talking about propeller efficiency we are actually ...
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What is the approximate thrust at sea level for a C-130J Hercules?
I am looking for the approximate thrust of a C-130J Hercules under ISA sea level conditions. Also the efficiency of its propeller would be of help.
An answer to this question would really help my ...
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How come the hover efficiency for tiltrotors is better than tiltwings?
How do you compare the hover efficiency of tilt-rotor and tilt-wing aircraft? The Wikipedia page Tiltrotor mentions:
Tiltrotors generally have better hover efficiency than tiltwings (...)
But I was ...
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What surface materials do airplanes use to reduce friction?
Full swimming body suits were banned from Olympic Games a few years ago because some materials have less friction than skin and contestants that could not afford gear to increase their performance ...
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Efficiency of the Kuznetsov NK-88 or NK-89 engine burning hydrogen
It's tough to find data about turbofan efficiency running on hydrogen.
The Tupolev Tu-155 has been used as a test bed for exotic fuels right before the fall of the soviet union, without much follow-up....
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Would it be beneficial to have rotors AND propellers instead of a tiltrotor?
Would it be beneficial for tiltrotor aircraft if they had BOTH rotors and propellers, instead of the hybrid proprotors that are neither good propellers nor good rotors?
Like imagine the V-22 Osprey ...
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How much is a swashplate system more energy efficient than a fixed blade system for the same load
When reading about the lifting capacity of swashplates (as found in helicopters) vs fixed blade systems (as found in e.g. DJI drones), I read a lot of comments about the fact that the bigger rotors of ...
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Does a constant speed prop maintain the optimal angle of attack at all time?
From an answer on this site:
The governor just knows: Speed too fast, flyweights move out, routes
pressure to move the blades more coarse; speed too slow, flyweights
move in, routes pressure to move ...
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Can any conclusions about aerodynamic efficiency be drawn on the basis of fly-by noise?
Edit: I'm beginning to think this is more suited to the physics stack exchange, but I'll keep this here for a while...
Being bored mindless, surfing the interwebz, I came across this video, where a ...
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increasing lift in a plane by placing engine in such a way that the air coming out of it washes over the wings to create more lift [duplicate]
I was wondering if the engines of a plane can be placed in such a way so that the air coming out of the engines goes from over the wings so that the velocity of air over the wing is higher and more ...
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Is high propeller pitch inherently inefficient?
For an airfoil, in general, the aerodynamic force is more or less perpendicular to the chord line.
A low-pitched propeller blade has it's chord line more perpendicular to the direction of flight, ...
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