# 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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### What's the reason of engine roughness while leveling off from climb or recovering from stall?

I want to find out that if relative wind pressure can affect engine or not.
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### Variable-pitch propeller blade design (AOA)

For a variable pitch propeller where the angle of attack can be adjusted during flight, are the individual blades similar in design to standard propellers, with a low angle of attack at the edge of ...
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### What is the range of ratios between optimal propeller efficiency and true propeller efficiency?

In https://aviation.stackexchange.com/a/15383/20394, the optimal prop efficiency is given as: \eta^{opt}_{Prop} = \frac{1 - \frac{\Delta v\cdot \left({v_{\infty} + \frac{\Delta v}{2}}\right)}{d_P^2\...
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### static thrust vs. prop RPM data?

edit: question was too long, and is actually simple, so I removed unneccesary description Background: There are many questions here about: propeller efficiency changes to thrust when it is dynamic ...
1 vote
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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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### Why the greater the propeller slip is, the more thrust it generates?

Forgive my poor English skill and my entry-level understanding of aviation stuffs. I'm currently a student pilot. As I understood, the propeller slip kind of represents the propeller efficiency in ...
1 vote
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### How reliable are the available airfoil data sources?

I am making calculations based on Blade Element (Momentum) theory (BEM) for propellers and I am trying to find the angle of attack at which the propeller performs most efficiently. If I have ...
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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 aircraft was the Olmstead High Efficiency Propeller for? When and how was it used?

The AFResearchLab video AFRL Tech Museum Series: Propeller Development begins with the narrator standing in front of four propellers in a sequence transitioning from wood to metal, and what stands out ...
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### Is there an equation for how fast air accelerates into lower-pressure regions?

I’m designing a propeller, and I want to plan the shape of the trailing edge of each blade such that (as much as reasonably possible) the pressure comes out as an “equal” line. Thus - I'm wondering ...
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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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### Can a fixed pitch propeller be designed to act as both a propeller and a generator?

The angle of attack (AoA) plays a major role in designing a propeller for specific uses, such as if it is to be designed for aircraft propulsion the AoA must be high, while the AoA must be low if it ...
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### Why do you have to turn off the prop sync when changing the engine rpm? [closed]

I understand how prop sync works, I just don't understand why you have to have to turn it off to switch the rpm. Is there something that I am missing?
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### Could small ramjets on the tip of propellers allow for supersonic spin of turbine blades?

Well, of course, if it was practical, someone would've already done that, but I'm still curious. As you can imagine, I'm an illiterate on the matter of aerodynamics, and even though supersonic ...
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### How would you design an airplane to counteract a single engine’s left turning tendencies?

How would you design an airplane to counteract a single engine’s left turning tendencies caused by torque, p-factor, spiraling slipstream and gyroscopic precession without pilot input or use of rudder?...
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### Why does the centrifugal twisting force move variable pitch propellers to fine?

In my research on the forces acting on and influencing a single engine, non feathering variable pitch propeller's ability to change blade angle, I've come across a bit of a roadblock. Aerodynamic ...
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### How does the Urbanaero flying car move forward?

From the pictures of UrbanAero flying car: https://www.urbanaero.com/cityhawk, I can see that can achieve VTOL using the two propeller in front of and in the back of the passenger compartments. ...
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### How does the wake behind a propeller blade affect the next blade if the airflow through the propeller should be clearing the wake?

Propeller or wind turbine often has only 3 blades,reason is wake behind each blade interfere with next blade. I think wind that comes to propeller must clear this wake,so faster you go the air for ...
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### What is propeller pitch speed?

I was using Ecalc to calculate some flight parameters and then I came across this term called "propeller pitch speed". Can anyone explain me what this means?
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### Why have propeller engines never been mounted on the tail in production transport aircraft?

Recently, Embraer teased this concept. Unlike jet engines, I have never heard of a production airliner or executive aircraft that mounted propellers on the tail like this. From the source: the new ...
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### What are techniques for balancing a radially folding propeller?

When balancing a radially folding propeller, such as the MagCAD 60x23, what are some techniques to employ? A static balance is challenging because the orientation of the blades is not fixed. Dynamic ...
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### Which popular turboprop engine feathers its propeller blades with each shutdown?

Chapter 12 of the FAA Airplane Flying Handbook, discussing multiengine flying, goes into quite a bit of detail in the propeller section about how most feathering-propeller-equipped engines on ...
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### What propeller for flying slow and efficiently? [closed]

So I'm getting into R/C flying and got myself a nice, but pre-owned trainer model. One of the things that need replacing is the propeller, which is a 2-blade nylon 10x8 with too many signs of damage ...
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### Variable pitch propellers: Why are they constant speed too?

I am studying for my PPL, and after going through aerofoils, lift, drag, optimal L/D ratio, propeller blades and the like, the need for a variable pitch propeller is absolutely clear to me. It is also ...
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### Do pusher propellers create the same yawing moment as puller propellers? [closed]

We know that the effect of P-factor on puller propellers is the yawing moment in the opposite direction. I mean if we had a load (thrust or lift) on the right side of propeller, then the airplane will ...
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### What would be the advantage of a Puller vs. Pusher configuration on Embraer's new Turboprop?

Embraer recently teased a turboprop aircraft with aft-mounted, open rotor engines. Why would this aircraft not use a pusher configuration? The reasons that are frequently stated as a benefit for a ...
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### What do "cork screwing" and "pushing air" have to do with propellers?

I am in the middle of my PPL(A) theory and I am experiencing a mental breakdown studying propellers. Until yesterday I was happily living in my ideal world where I was sure I really understood all the ...
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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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### Why, with a constant speed propeller, does moving the propeller control forward increase drag?

Could someone explain why, let's say in a constant speed propeller, with moving propeller control forward the drag increases? It is noticeable when we push the blue knobs forward in flight that the ...
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### Why does a low pitch propeller have better acceleration/take-off and climb characteristics than a high pitch propeller?

Why does a propeller with a low pitch have better acceleration/take-off and climb characteristics vs. a high pitch propeller? And conversely, why is a propeller with a high pitch not as good during a ...
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### Were propeller airplanes significantly more "scary" to fly in compared to modern jet ones?

I've flown exactly once in my life. It was in 2004, with a commercial jet. Not a "jumbo", but a normal-sized jet plane in common use for cheap flights in that year. (Well, twice if you ...
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### How do witness marks on propeller blades provide data on estimated blade angles at the time of impact?

In the NTSB Powerplant Group Chairman Factual Report for the 2014 crash of the King Air B200 in Wichita Kansas (NTSB# CEN15FA034), I read: "Neither propeller was feathered before impact. Both ...
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1 vote
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### Calculating the Thrust vs RPM Relationship of a Brushless DC Motor

hope everyone is doing okay. I am conducting a project with my friends for an Unmanned Aerial Vehicle. We are first using MATLAB - Simulink to design and simulate the quadrotor. We completed the ...
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### What is the certification process for a new propeller blade design?

I am wondering whether a propeller blade design (say from Hatzell) is submitted to a specific agency for testing and approval, and if these designs are then registered. Looking through Hatzell's ...
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### In constant speed propeller, if i increase RPM lever from 2300 to 2500, will the Blade AOA decrease?

Assume I am flying straight and level with power setting 21 inches of MAP and 2300 RPM with TAS=100 kts, now I change my Prop lever only (MAP = no change & TAS = no change) from 2300 to 2500, ...
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### What are the black boots on this Extra 300's prop?

I normally think of black boots on a prop as being for de-icing. However, the Extra 300 is not suitable for known-icing conditions, or even IMC flight. (It's AFM says "Only VFR flights at day are ...
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### Is pitch-flap coupling an aerodynamic effect or an intrinsic property of a delta 3 offset?

I am modelling a propeller, in particularly the equations of motion of the various pitch/lag/flap angles as the propeller is turning around. The blade includes a $\delta_3$ angle, which provides pitch-...
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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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### How to decide the diameter of a propeller and number of propellers needed in a UAV I am designing? [closed]

I want to design a turboprop aircraft. I know all the design parameters such as lift, thrust, weight etc at a given flight stage. I want to know what the size of the propeller should be.
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### How do electric propeller governors (or electrically controlled governors) work and what are their pros and cons?

I am trying to understand why electric propeller governors are not (yet) prevalent given that they offer the ability to control the RPM with high accuracy. What is the typical architecture for an ...
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### Calculate propeller efficiency [closed]

I have a test bench that can test the thrust of a propeller with my electric motor, is there a way that I can calculate the propeller efficiency (ηp)?
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### Why do propellors have white markings on their tips? [duplicate]

Why do propellors have white markings on their tips? Here are a couple of examples:
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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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### Fly a fixed wing single propeller airplane like a helicopter?

Has anyone tried to "helicopter" an airplane? And succeeded? And posted this video on the internet where I can find it? What I'm talking about with what I would call a "helicopter&...
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### What is the difference between RTOP, MTOP, and MCP?

I am currently learning how to fly the SD3-60 (Shorts) Aircraft, and I am trying to gain an understanding of RTOP (reserved take off power), MTOP (max take off power), and MCP (max continuous power). ...
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### Retreating Blade Stall, P-Factor, and Gyroscopic Precession

Most airplane pilots are aware of P-Factor in propeller driven aircraft and that it tends create a torque in phase with the lift imbalance over the blade disc, resulting in a yaw moment about the ...
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### What are the pros and cons of putting a propeller immediately before a slipstream pylon vs. immediately after

In the following situation with a slipstream pylon for a self-launching glider, what are the tradeoffs in sticking the propeller before vs. after the pylon? The wind turbine industry has the same ...
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### Is possible to stick two '2-blade' propellers to get multi-blade propeller?

Does propeller blades' airflow interfere with each other blades and decrease overall thrust? Should I consider high pitch propeller for this purpose? My purpose: I'm looking for a 20-inch four-blade ...
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### If an elliptically-shaped aerofoil gives the optimum lift distribution, why aren't propeller blades designed around this ideal?

So given an elliptical lift distribution is the most efficient, why are propellers not designed around this? Props aren't affected by the adverse stall characteristics that concern a "main", ...
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