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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1answer
133 views

Propeller Curve Modification on Test Rig

this is my first stack exchange question so please bear with me if I have missed a rule: I tried searching for this question to no avail. I have an off-the-shelf propeller for the purpose of eventual ...
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1answer
329 views

Why don't the ATR 42's propellers start/stop rotating simultaneously?

Why is it that for the ATR 42 one of the propellers begins to rotate before of the other? I've noticed that they also stop rotating at different times. Is there a reason for that or is it just for ...
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Why autogyros use pusher-, whereas, piston-engined planes use puller-configuration?

I found that most modern gyrocopters use a pusher-configuration, whereas, most piston-engined planes use puller-configuration. Since the pusher-configuration has major disadvantages, are there ...
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Why don't helicopter rotors use curved blades? Curved from the top view. [duplicate]

I'm studying blade element analysis and I tried applying it to curved rectangular blades instead of straight ones. It doesn't really show any significant changes in the inflow ratio computation. Why ...
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2answers
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Pros and cons of a pull-push propeller configuration [closed]

What are the pros and cons of a pull push propeller in comparison to a counter rotating propeller?
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How to realistically model propeller static thrust?

I am graphing static thrust vs prop diameter for a 600 kW motor and a prop diameter up to 5 m. I have seen the post 'What is the equation for calculating static thrust?' and using its formula and ...
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2answers
249 views

How long does it take for a propeller engine to spool-up?

To build further upon the question Why does a turboprop lag?, the following: Assuming a propeller engine is running in idle and the throttle lever is switched to full thrust instantaneously at t = 0 ...
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381 views

Is a cambered or symmetrical propeller airfoil more efficient?

Is an cambered propeller more efficient than a symmetrical propeller for a low speed airplane?
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456 views

Will the steep beta descent mode become illegal for new aircraft?

The PC6 is a popular skydiver carrier due to its ability to use steep nose down beta descent to get back to the ground quickly, even beating free falling skydivers. (YouTube) FAA AC25.1155x (I only ...
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2answers
206 views

Why Consumer Drones don't use multi-blade (more than 2) propellers?

Maybe unusual question but it's related to Aviation world, even if is more directly related to Drones one. Why almost all consumer drones like DJI's and Yuneec's ones (but it's true also for other ...
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At what rpm does the tip of a 54" propeller start to incur mach losses?

At what rpm does the tip of a 54 inches propeller start to incur mach losses? The max rpm of my engine is 3600.
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Is a propeller with two long blades more efficient than one with three shorter blades? [duplicate]

Is a longer, two-bladed propeller more efficient than a three-bladed propeller with a smaller diameter?
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2answers
206 views

Which engine manual must a pilot legally use?

Many aircraft have engine/prop performance information provided by the manufacture such as Bonanza, Cessna, Mooney, etc AND the engine manufacture. The performance or recommended settings may vary ...
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729 views

Would a coaxial propeller with the second prop slower and larger improve speed?

Looking at various propeller designs, I started wondering about these limitations: Large propellers at high speeds have tips going supersonic Scimitar props attempt to keep prop tip from going ...
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397 views

Does the direction of rotation of the propeller affect the direction of the thrust generated?

Does changing the direction of rotation of the propeller from clockwise to anti-clockwise change the direction of thrust it generates?
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359 views

In what way are the airfoils used for a propeller different from the ones used in turbofan engine?

Airfoils are used in the blades of a propeller as well as the blades of the fan, axial compressor and turbine in a turbofan engine. Thus, the airfoils used in above two applications have different ...
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Is this equation for propeller thrust correct?

From dimensional considerations, and assuming that the power $P$ applied to a propeller of diameter $D$ moving at an axial speed $V$ is 100% converted to the acceleration of a mass of air with density ...
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1answer
263 views

What is the relationship between speed, torque and pitch in a helicopter?

Can someone clarify the relationship between aircraft speed, torque, prop length and pitch and how this applies to a helicopter. In addition I want to know if the amount of lift a helicopter ...
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615 views

Why do helicopter rotors have constant section and angle of attack?

As I understand it helicopter rotor blades keep a constant aerofoil section along their length, and are not twisted. Other rotating aerodynamic devices such as propellors, turbofan fans and wind ...
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How do propeller planes suddenly make noise?

I was wondering: how can a propeller plane, single engine or otherwise, be flying along relatively silently and then start making noise, often very loud--and then turn it off just as quickly? Are they ...
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364 views

Is there a fixed-wing aircraft that uses a scissor propeller configuration?

(Source: primeportal.net) Has there ever been a fixed-wing aircraft whose propeller is in a scissor configuration? Like the Apache's tail-rotor seen here: What are the benefits of a non-orthogonal (...
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Would propellers be more efficient if they were mounted at the rear of the aircraft? [duplicate]

The propellers of a front-mounted propeller plane push air back directly on a collision course with the aircraft's body. That results in zero thrust or negative thrust from at least some sections of ...
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How much safer does painting prop tips make a plane?

While re-reading one of my earlier questions, the answers left me wondering how much good painted tips on props actually does. I did some searching for statistics but didn't come up with much. Are ...
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What typical improvements in lift/drag are gained using dimple & zig-zag strips? [duplicate]

A golf ball goes twice as far using a dimpled surface. Many European aircraft (especially gliders) use dimple strips or zig-zag tape on propellers, wings, struts etc. Very few US aircraft use these ...
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What are the design trade-offs between a pusher and a puller propeller? [duplicate]

Wich is the difference in having the propeller forward or back in an airplane. I would like to know the technical differences like in a Piaggio 180 or in a normal Cessna.
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Does rolling affect the thrust of a propeller?

If a plane with a propeller, e.g., a Spitfire, does a constant barrel roll in the same direction as the propeller, will the plane travel faster as impractical?
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Why are there different number of propeller blades on the inboard and outboard engines?

The Junkers G 38 has four propeller blades on the inboard but only two on the outboard engines. What's the reason for this special arrangement and is there any benefit?
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Is there a mathematical formula to find the most efficient propeller? [duplicate]

Is there a mathematical formula to find the most efficient propeller? Is a five-blade better than a four-blade? Does software exist to aid in the calculations there?
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1answer
608 views

Is there a pressure rise and velocity change across a turbofan fan and stator?

I've been looking at the pressure / velocity / temperature diagrams across jet engines. These have really helped me to understand the different roles that the compressor/turbine stator and rotors play,...
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Guidelines for using a constant speed/adjustable pitch propeller

I have been trained in a single engine fixed pitch prop ( C152). I'm trying to move to Piper Arrow II which has an adjustable pitch propeller. I understand how constant speed propellers work. I'm ...
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1answer
825 views

Would it be possible to build a “rocket” using a series of ducted fans?

I'm wondering if it would be possible to build ducted fan "rocket". My idea is to construct the duct from 18650 batteries, and to have a series of contra rotating fans along its length. I can 3d ...
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How to calculate Blade angle?

If we know the helix angle is 3angle, forward speed is 150mph, and rotational speed of propeller is 1500rpm How can i calculate the blade angle of propeller ?
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How do I compute thrust of a rotor disk and the necessary power to drive it??

as it seems, this question has been asked a few times here so please forgive me for asking again. If I have 50 BHP shaft power available at 5000 RPM and 106 N.m torque, then can I convert it to 200 ...
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How far should the two propellers on a twin engine plane be apart?

I was wondering if there are any specific ways to calculate the appropriate distance between two propellers for a twin engine twin fuselage planes like a Twin Mustang plane?
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Can an ultralight aircraft fly with a 18hp engine?

I have some questions - I'm planning on building single seat UL aircraft with this plan sketch (I have more), I drew this based on real plain and some research. Empty weight is between 50-70kg with ...
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1answer
363 views

Why use jet engines instead of propellers when designing new airplanes?

I'm looking at the 100 people project and I am looking at clean airplanes. Why did we stop using a clean source of lift, the propeller?
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Does contra-rotating vs regular propellers, have any effect on icing?

I am trying to understand whether can there be any correlation between the contra-rotating propellers and the ice accretion over the wing ? For instance, is there any evidence that ice accretion is ...
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Ducted Fan vs Open Propeller Efficiency [duplicate]

If we are talking about a slow flying aircraft with subsonic propeller tips, will adding a shroud increase efficiency, all else being the same?(ignoring the friction drag)
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1answer
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How does a fixed-pitch propeller changes the blade's angle of attack?

Studying I have found a question that states that in a fixed-pitch propeller in flight at a given TAS, the blade's angle of attack will change if RPM increase, but I don't understand how can the blade'...
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627 views

In a piston aircraft, how much noise is generated by the engine, and how much by the propeller?

I've been reading quite a few articles lately about how noise complaints from GA airports across the country. One of the common suggestions to fix the issue is to simply use an electric engine ...
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How was the rotation direction decided for single engine propeller craft? [duplicate]

Spitfire, FW-190, Ki-43... was it selected arbitrarily to spin counter-clockwise?
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What calculations are needed for counter-weight balancing on a propeller?

I am designing a small-scale propeller and i have managed to design on optimized geometry for the blade. However the blade pitch angle adjusts according to different flow speeds so i need to mount ...
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1answer
523 views

Can I model propellers used in electric aircraft the same way as I model RC quadcopter drones?

I am writing an article about mathematically modelling a flying car, using D'Alembert's principle. I need some information about the propellers ... When I worked with the mathematical model of a small ...
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2answers
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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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3answers
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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 ...