# 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 many ways/methods to calculate propeller/rotor's power output? Which one is the best?

Source: Wikipedia I want to know how many ways/methods to calculate the output power of a propeller? So far I knew three methods: Momentum Theory (MT), Blade Element Theory (BET), Blade Element ...
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### Are narrow propellers more efficient than wider ones?

I came across this company E-Props that builds propellers and it seems like all their propellers are narrower, at least narrower than traditional ones I'm used to see, and I see on their picture ...
1 vote
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### Propeller Torque Calculation

Propeller torque is given as $Torque = c_p * ρ * (\frac{ω}{2π})^2 * d_p^5$, where $c_p$ is the torque coefficient, ρ is the air density, ω is the angular velocity, and d is the propeller diameter. I ...
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### Is there a convention of propeller tip separation from the wind tunnel walls?

Blockage ratio is commonly used to address the effect of confinement on the propeller's performance tested inside a closed test section of a wind tunnel. In most cases, blockage corrections (like ...
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### Could a propeller system for airplanes with automatic, cyclic blade-pitch control that is designed to counter p-factor be practical?

Considering that P-factor is a result of differing angles of attack of the blades on an airplane's propeller, I would imagine that if there was a design that could control the pitch of each individual ...
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### How to calculate velocity of air behind a propeller?

Background: I came across this article by Gabriel Staples to calculate static and dynamic thrust of a propeller. In the derivation, it was assumed that the exit velocity is equal to the pitch speed of ...
121 views

I'm balancing a three-blade propeller. The propellers weigh exactly the same to the 10th of a gram. When I place it on shaft with a very sensitive wheel bearing, one of the blades always moved ...
1 vote
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### McCauley propeller models IC235/LFA7570 and IA170E/JHA7660

I am writing to inquire about the pitch specifications for the following McCauley propeller models: IC235/LFA7570 with a maximum diameter of 75 inches and minimum diameter of 74 inches. IA170E/...
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### How can I find the minimum and maximum airspeeds for efficiency with a specific prop/engine combination?

I'm operating a Cessna 180 with various wing and weight mods with a TCM IO550D engine and a McCauley Black Mac (D3A34C401/90DFA-2 3 blade (88 inch) seaplane prop. I operate Lean of Peak (LOP) for most ...
1 vote
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### Could a WW2-era Grumman Hellcat land on a Saipan-class light carrier using only reverse-thrust generated by a reverse-pitch propeller?

Just that - take away an F6F's arrestor hook and fit it with a reverse-pitch-capable propeller (and, of course, all the other odds-and-ends to make such a system work). Would it be possible for a ...
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### How to design a propeller that works efficiently in reverse?

I'm designing a UAV that needs to reverse motors for some maneuvers, but unfortunately most of the commercially available propellers I've tested are optimized for single direction and only produce ...
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### Determining Sectional Drag Coefficient Using Propeller Geometry

Im trying to teach myself blade element theory for helicopters and propellers, but im getting quite confused. Most of the papers and textbooks I read will reach an equation for differential thrust ...
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### Do constant maximum lift to drag ratio variable pitch propeller exist?

Are there variable pitch propellers, where pitch is set so that the blades constantly are at their maximum lift to drag ratio AoA, whatever the incoming relative wind speed & direction? Such a ...
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### Is the math behind my approach to design a propeller right?

I'm trying to design a fixed pitch propeller of diameter 1.8 m flying at 10000 ft going at forward velocity(85 m/s). What I've done is take a series of airfoils (from root to tip), found the ...
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### Where does "wasted" propeller power go?

Aircraft propellers are very efficient, with around 80-90% of input horsepower being applied to axial flow. However, that raises the question of where the remaining 10-20% of energy goes. I'm ...
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### How can I cross verify my propeller thrust? [duplicate]

I'm simulating a propeller in Ansys and im getting a thrust of 2000N. The forward speed is 85m/s and 240.25 rad/s angular velocity and the diameter of the propeller is 1.8m. Since I'm not able to find ...
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### How does the location of a propeller affect an aircraft's stability?

Some aircraft possess propellers on front of the fuselage, like the Cessna 172, and some aircraft have propellers located at the rear of the fuselage, like the Velocity 173RG-E. How does the ...
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### how can we calculate normal force or vertical component of propeller in an aircraft?

when we calculate thrust of an propeller engine we also face to vertical component or normal force which change neutral point of an aircraft how can we calculate this force? thank you
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### What's the thrust of a given propeller at zero airspeed?

If memory serves correctly, propeller thrust for a given propulsive horsepower is inversely proportional to airspeed, assuming features like constant RPM prop, and being outside Mach Effects The ...
1 vote
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### How to retrieve the thrust distribution over a blade using XROTOR?

What is the procedure for retrieving the thrust distribution over a propeller blade using XROTOR? I need the sectional (i.e., for each station) thrust coefficient values. I was only able to retrieve ...
137 views

### When discussing a “feathering, counterweighted propeller” where are the counterweights?

We are learning about propellers in school. To my understanding, generally a non-feathering, non counterweighted prop uses centrifugal twisting moments to lower blade pitch while oil pressure is used ...
525 views

### Could a quadcopter fly if its propellers were encased in cylindrical tubes?

Picture a standard quadcopter, with regular old propeller guards, which are generally just circles around the propellers. Now, take the propeller guards and stretch them so that they're cylinders ...
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### What does "Rotating airfoils of engines" mean in the US Code of Federal Aviation Regulations?

In part 1.1 of the US 14 CFR, definitions and abbreviations, a propeller is defined as: ...a device for propelling an aircraft that has blades on an engine-driven shaft and that, when rotated, ...
1 vote
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### Propeller Characteristics at Different Altitudes

Assuming I have a propeller with a given diameter (D), pitch, blade twist, and number of blades, I can theoretically analyze discrete airfoil sections in XFOIL and come up with lift and drag polars ...
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### Is there a standard way to identify propeller blades?

Obviously, as Julio pointed out, Chuck's method of identifying propeller blades is ineffective. Is there a standard way to identify blades, other than tautological statements like "There is a ...
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### Does propeller width have a material impact on thrust? [closed]

I have seen propeller thrust calculations and they do not appear to have the variable of propeller width. They only use diameter or radius. What if any impact does width of the propeller have? Here is ...
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### How does Propeller windmilling work?

I’ve got a problem with understanding propeller windmilling. What I know is that when rpm are low and tas is high the blade aoa goes „over” the blade and is some kind of negative now, producing thrust ...
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### Hypothesis: swept back propeller would reduce drag and increase thrust [duplicate]

Hypothesis: swept back propeller would reduce drag and increase thrust. Any experience with this?
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### Deriving Accurate Exit air velocity of rotor

My goal is to derive the equation for exit air velocity as a function of: Pitch angle RPM Rotor Radius Constants like ρ Assumptions: Vc is relative velocity of air upstream, and is = 0 Inflow is ...
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### Can an airplane propeller become supersonic?

Is it possible for an aircraft propeller to become supersonic? I am not referring as for the aircraft, only the rotating blade. I know it is extremely unlikely for a propeller plane to go supersonic, ...
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### Actual non-axial airflow (sideslip) for a propeller driven aircraft

I am making a propeller model for a two-engine propeller driven aircraft (like a Dornier 228). I have expanded my model to include the non-axial airflow as well.  By non axial airflow, I mean ...
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I have heard that propellers with more than four blades are not as efficient as 4 or less blades because of lower thrust which may result from interfering prop-streams. But I see the ATR-42/72 and ...
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### What types of wood can be used for making propellers?

Early propellers were made from wood and they still are on some vintage/classic aircraft and reproductions. What types of wood are typically used to make wooden propellers?
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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 ...
1 vote
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### Does the obstruction in a propeller duct increase exhaust pressure or decrease pressure/increase speed?

I came up with this question when looking through the answer for this question, which states that a convergent duct(obstruction) compresses the exhaust so that its pressure matches the ambient ...
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### Can you weld a propeller blade from 120 degrees to 180?

My uncle flew for Mission Aviation Fellowship (maf.org) for a university in Texas, and I believe that he was flying a Cessna to the Amazon (among other places). He actually knew Jim Elliot (who went ...
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### Are there any variable-diameter propellers?

Have there been any known tests or prototypes of variable-diameter propellers? There's this paywalled paper from 2014 that seems to have made a virtual prototype model, have there been any physical ...
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### Could floppy rotor blades be usable?

Autogyro and helicopter blades are more or less flexible, and when not stiffened by centrifugal force they droop noticeably. A extreme case would be that of fabric blades. They have been used at least ...