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Questions tagged [propeller]

Aircraft propellers are airfoils which convert rotary motion from a piston or turbine engine into thrust suitable for propelling an aircraft.

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How to design the blade twist angle in propeller design?

I am designing a scale propeller for small UAVs and I have computed blade twist distribution for the blade airfoil sections. While I was modelling the propeller I have set the angles to twist about ...
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What do I need to know to design contra rotating propellers for a powered paraglider?

I wonder if anyone has any technical information that would assist in using the correct Size & Pitch Contra rotating Propellers (CRP) on this Foot launched Powered Paraglider engine ? We are ...
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Do propellers generate static electricity in flight and how is that handled?

How is the risk of tribocharging (static electricity generation) by the propeller managed on an airplane? Regardless of airplane size, it seems the rotation of the propeller or engine blades could ...
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What Inertial effects should be considered to achieve blade stability on a Variable Pitch Propeller tailoredby aerodynamic loads?

I am developing a self adjusting variable pitch propeller tailored by its pitching moments due to aerodynamic loads setting the blade rotation axis in an offset from the aerodynamic center as shown ...
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What's the use of so much torque on propellers?

(This question is closely related to this question) A typical Cessna 172 has a 180 hp engine, with a max. rotational velocity of 2700 RPM. Even small 1 hp electrical motors can achieve that RPM, and ...
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What is the typical blade pitch angle of a ram air turbine?

I'm building a simple 3d model of one and because reasons I won't be able to give it a variable blade pitch so I need to find a typical value. My google-fu has failed me so far on this.
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In a constant speed propeller, why does the RPM drop with a prop pitch increase?

When a constant speed propeller changes its pitch from low to high, RPM would decrease. Why is that the case? Wouldn't the RPM increase when we increase the blade angle since there's less drag and ...
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Why are 4 blade propellers often in X or + position when the aircraft is parked?

Is there a meaning to the position of 4 blade propellers on parked warbirds? A lot of old pictures have them at X or + positions.
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How to find trim condition of a sectional airfoil without knowing the angle of attack?

I am using a reflexed airfoil designed for positive pitching moments to achieve a pitching angle matched to the changing of free-stream velocity (Aerodynamically tailored). I ended up with a pitching ...
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1answer
539 views

What is this three-bladed vintage aircraft?

We found this poster at IKEA, EDELVIK Poster 103.776.29. Allposters.com has another poster, which includes the same aircraft, but 2 in formation, possibly the same original photo/artist?
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How to calculate variable pitch propeller parameters?

I'm carrying out a project on Variable Pitch Propellers for UAVs and especially self-adjusting or Passive Variable Pitch Propellers that change pitch due to aerodynamic forces and Pitching Moments. ...
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What are the reasons behind this pusher propeller configuration?

Can a pusher configuration sort of like this have its propeller close to the tail (if it were one of those split tails like on a A-10)? Why did they put the propeller above the cabin and not in ...
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Can drone with two propellers above one another fly vertically upward without spinning? [duplicate]

Basically, like the propellers setup in this image without the tail end bit: Where the propellers will be spinning in opposite directions. This would, in theory, counteract the angular momentum to a ...
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Why doesn't the plane accelerate/move forward when it's at rest, if the propeller is spinning?

I'm having difficulty seeing the difference between a stationary plane and a moving one. When you start the engine in the C172, the blades on the prop are spinning - but the plane doesn't move at all....
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Shaftless propeller vs duct fan [duplicate]

If both have the same dimension, same amount of fan blade, and supplied by the same amount of energy, which one would product bigger thrust and less total drag (the drag on the blade and the "tube" ...
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Why do propellers on aircraft have a slight offset angle?

Single-engine aircraft (one propeller on the 'nose') Why do propellers on aircraft have a slight offset angle? I have picked up this information that the rotational axis of the propeller is not ...
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Why are there curved propellers? [duplicate]

Why are there curved propellers on some aircraft, what is there advantage? If these are worthwhile advantages why aren't there curved blades on turbo fans?
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604 views

Why is the available power in propeller engine is almost constant for every velocity?

I surfed on the internet for an answer but I didn't find any. I'm taking Aircraft Performance course. I saw that available power for propeller engine is almost constant for every velocity. But I don'...
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Are there any ducted propeller or fans without a shaft in the centre?

Are there any propeller or fan designs that hold the propeller or fan in the duct and do not have a boss or propeller shaft? This could reduce the drag of the centre. Are there any other advantages?
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Aerodynamics of a Propeller [duplicate]

I'm having troubling understanding where the relative wind is coming from for a propeller. The relative wind that I do know is the one that comes right in front of the aircraft which flows over the ...
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1answer
4k views

How much lift must a helicopter rotor produce?

How much lift must a typical helicopter rotor produce? For example, consider the rotor of what seems to be a common helicopter: the Robinson R22. Is the lift produced equal to one of the following: ...
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1answer
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How much thrust is gained from placing a propeller in a duct?

Assuming that the power and diameter are the same, how much extra thrust can be gained by placing a propeller in a duct? How does it influence the RPM? To clarify: take any prop, place it in a well-...
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How does blade solidity ratio relate to thrust/power/torque of a propeller?

for quite some time I was using ABBOTT formula for static thrust estimation on a two-bladed propellers: $$ T=6.8\times10^{-5}\times D^{3}\times p\times RPM^{2} $$ $T$ is Static Thrust (N); $D$ is ...
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Where can I find info or techniques on calculating the influence of a duct on the thrust and efficiency of a propeller?

I am trying to run numbers on a concept VTOL fixed-wing aircraft, and I am looking at having fans or props positioned inside the wings, (which would therefore make the wings relatively thick for a ...
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Why does this analysis show very high stress in a propeller?

I have been trying to evaluate the stress on aluminium propeller: Diameter: 78", 2600RPM Have fed load numbers from here, applied distributed mass model onto the blades. ...
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1answer
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What is the optimum separation between contra-rotating propellers?

What is the optimum separation between contra-rotating propellers? What factors determine the distance between the two sets of propellers?
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Why is max endurance different for jet and props?

Max endurance speed is not the same for gliders, propeller planes (also for turbo prop, right?) and jet planes. While for for jet planes max endurance is at the minimum drag speed ($V_{md}$), for ...
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What is this odd aircraft?

What is this aircraft? It was parked at transient parking at the Southern California Logistics Airport. It is a pusher prop driven plane with a conventional tail. High aspect ratio un-swept wings. ...
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Could this propeller work on a quadcopter and decrease the sound?

I came across a video yesterday that showcased a propeller design that looked very interesting. I am a regular drone flyer and I constantly look for exciting things to try out. Would this design in ...
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Why don't drones use ducted fans?

If efficiency of converting battery power to lift or thrust is paramount, why don't drones use shrouded or ducted fans, instead of unshrouded propellers? This is the only image I could find to ...
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1answer
317 views

Do all the engines/propellers of a VTOL UAV need to be identical?

I would like to know if VTOL UAVs necessarily need $n$ identical propellers and motors. Have any design solutions considered the possibility of using non identical props? For instance 2 motors of type ...
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Which 'pusher' propeller aircraft have been used in active military service?

The only 'pusher' aircraft I know of that has been used in active military service is the SAAB 21. There are several prototypes out there, but I can't see that any others were used. Which, if any, ...
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What contra-rotating propellers would be appropriate for this engine?

I am currently getting an X4 cylinder, 150cc, 4 stroke engine 3D CAD Modelled, this engine is initially being designed for Powered Paragliding (PPG), classified as experimental Aircraft, so no ...
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1answer
527 views

Do low-cost airlines make more profit than luxury airlines? [closed]

I was watching this TV show and it said that currently low-cost airlines e.g. Ryanair/Easyjet make more cumulative profits than more expensive long haul airlines such as British Airways and Virgin ...
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What are some of the largest propellers post-WWII?

(Source) The propeller on the Linke-Hofmann R.II (1919) holds the record at 6.9 m (22 ft 6 in). What are some of the largest propellers post-WWII? Top 5 or so.
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What is the difference between a propeller and a rotor?

I have been making the mistake of using words "propeller" and "rotor" interchangeably when they are not the same thing. What is the difference between a propeller and a rotor?
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Why are the top speeds for jet engines higher than for propellers?

I realize turbines are more efficient than piston engines, but if that were true, then why don't turbo-props reach jet speeds?
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At what point is a turbine powered ducted propeller considered a turbofan?

Turboprop Propellers can be ducted for extra thrust. What are the criteria for determining that the engine is no longer a ducted propeller design, but a turbofan? Does there have to be a type of ...
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1answer
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Why don't contra-rotating propeller configurations with more than two propellers exist?

I wasn't able to find a single example of more than two propellers stacked axially in a contra-rotating configuration. There is a huge number of contra-rotating propeller setups, but it is always a ...
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1answer
680 views

What is the force to change the pitch of a variable pitch propeller?

At the moment I am struggling with the problem that I do have an idea how to calculate this force by using the blade element theory and going over a whole propeller blade in order to calculate the ...
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1answer
568 views

Do propeller coefficients go to zero at the same value of advance ratio?

Graphs of power coefficient ($C_P$), thrust coefficient ($C_T$), and efficiency ($\eta=JC_T/C_P$) of the 5868-R6 propeller as functions of advance ratio ($J=V/(nD)$) and propeller pitch (blade angle ...
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What causes these losses in this propeller simulation?

While running a CFD simulation comparison of 2 vs 3 blade propeller versions (48" diameter, 23" pitch, 3570RPM), I've come up with: 2-blade: 347N of static thrust @ 110Nm Torque 3-blade: 220N of ...
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How do blade cuffs help cool the engine?

How does the blade cuff (a fairing of suitable airfoil shape used to cover the shanks of propeller blades in order to reduce the aerodynamic losses) help cool the engine?
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1answer
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What happens when a propeller is placed in beta while feathered?

Could someone explain beta range to me? What happens when we set the throttle control lever to the beta range (reverse thrust) while the propeller blades are in the feathered position? Will the ...
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2answers
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Do jet aircraft have an emergency propeller?

I once heard, or misheard, this: There is an emergency propeller that comes down in an emergency of jet-engine aircraft. It is behind the main landing gears. Is this true or a story somebody made ...
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3answers
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How does the relative wind on a propeller, strike the blade from behind (the non camber side)?

This may be a stupid or simple question, although any help is appreciated! :) If possible, please answer without mathematical terminology. So I understand the concept of the blade increasing air ...
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Rotation direction for adjacent propellers, how do different arrangements compare?

(YouTube) The Airbus A400M uses counter-rotating pairs where the blades meet moving downward (if there is a better description, tell me please). I played the video frame-by-frame to make sure it ...
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Why do solar planes have many small propellers instead of fewer large ones?

Many solar planes, like NASA's Helios (pictured above), NASA's Pathfinder, and to a lesser extent Facebook's Aquila employ the use of many small motor propeller sets instead of one or two engines like ...
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why are airplane propellers always undersized?

While calculating propeller static thrust by using a famous Prop-power-calculator.xls (by Pé Reivers), I've noticed that no matter what "stock" configuration I put into the calculator, I do always get ...
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Feasibility of using secondary props to generate power on an electric model aircraft [duplicate]

Beginning with the aeroplane itself, it is a small, fixed wing model aeroplane, reminiscent design-wise to a Cessna 172. It is completely battery powered and has a primary prop attached to a motor ...