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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2answers
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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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Are there any safety features to prevent reversible-pitch props from reversing in flight?

Some aircraft have propellers capable of reversing pitch, which is also known as beta angle. The example I saw was an Aviat Husky. (Youtube demonstration) I want to know if there are any safety ...
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Do contra-rotating props have worse tip vortices than single props?

As I understand it, blades from a propeller have their own tip vortices, because the blades produce lift via the same aerodynamic principles as wings. So they must have tip vortexes too. So with ...
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Does a windmilling propeller create more drag than a stopped propeller in an engine out scenario?

For this question lets assume that we are talking about a fixed pitch propeller and not a variable pitch propeller. I do understand that variable pitch props should be feathered during an engine ...
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Advance ratio formula for drone propeller in vertical climb

According to this wikipedia article. There are two expressions for advance ratio: For propellers: $$J = {V_\infty \over nD} \tag{1}$$ For helicopters: $$\mu = {V_\infty \over \Omega r} \tag{2}$$ We ...
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How are the Tupolev Tu-95's blades shaped?

The Tupolev Tu-95 "Bear" seems like an awfully cool piece of innovation with its unusual contra-rotating supersonic-tipped props. From what I've been reading it sounds like it's been the only mass ...
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Why do most propeller-powered planes not have an autothrottle?

Why does every kind of propeller-powered plane lack an auto-throttle? No single-props no twin-props, not even turboprops like the Dash-8 Q400. To be honest, I don't know many turboprops, but if the ...
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How do I get a copy of a Pilot Operating Handbook? [closed]

I need the POH for a Cassutt Plus or any variation for a University Project but I can't seem to find anything on the plane. Any other information (flight capabilities etc) would be helpful - with ...
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How much could human power add to the endurance of an electric gyrocopter?

If we take a single seater electric gyrocopter like this one, could a human-powered propeller like this add to the endurance of the aircraft? The gyrocopter only needs a 32km/h forward speed to stay ...
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What is the purpose of having contra-rotating props on an aircraft?

Why do planes, like the famous XF-11 and the Tu-95, have contra-rotating props? What is their purpose? Image credit: Mike Freer / Touchdown-Aviation / Wikimedia
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What is areodynamic imbalance?

What is aerodynamic imbalance on a propeller? The most amount of hint I got was the shape of the airfoil. All I know is that it is the different thrust each prop blade produces due to different angles ...
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What is a biplane propeller and how efficient is it?

Lazair ultralight series II used biplane props to absorb more power from the engine....so my question is what really is a biplane propeller and are they efficient in comparison to a four bladed prop?
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What is the Angle of Attack of this Propeller?

Photo 1 and photo 2 from here, photo 3 is from here. Here are three propellers. As in my understanding, the AoA or the pitch of a propeller should be close to its rotation's direction, around 15 ...
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Do contra-rotating propellers have the same RPM?

Image source Here is a contra-rotating propeller. The front propeller rotates counterclockwise while the back propeller rotates clockwise. My questions are: Do they rotate at the same speed (RPM)? ...
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Is any convention to tell the propeller rotation direction of an airplane?

Here are two airplane with single and dual engine. From single engine airplane we know there is TURN LEFT tendencies. There are four tendencies (Torque reaction, Precession, Slip Stream, and P-Factor)...
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What airplane model was this historic propeller attached to?

I have a 9-foot historic wooden biplane propeller with brass edges. It does have a serial number, but it is tough to read. 2250 DN 152 6' 6" is what it appears to say. I am attaching a photo of it. ...
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What were the disadvantages of early prop driven blended-wing aircraft?

I've been researching the history of pre-jet aircraft and I've come across several famous, and not so famous, blended-wing aircraft. The idea seemed to show promise but never really caught on, even ...
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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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Does the required torque to spin a propeller increase with RPM?

I‘ve currently been experimenting with different propellers: 12x12 prop, 16x12 prop (both two blades) and a 22x14 (6 blades) prop. They were propelled by a 2.4 kW electric motor with 260 kV on a 6S/...
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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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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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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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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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Is there any equation to bind velocity, thrust and power?

I am designing a remote controlled airship. I will tune it so that the lift given by Archimedes' Principle will exactly balance the weight of all the structure. It will be propelled by brushless ...
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Do surfaces ahead of propellers decrease thrust?

I have had this question for ages, nearly impossible to find anything on the web. My experiments confused me even further! Its concerning the blockage effects of surfaces ahead of a propeller. For ...
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How much thrust could a 400 mm EDF produce?

There's a 195mm EDF from Schübeler that produces 25 kg of thrust at a peak power consumption of 15 kW: https://www.schuebeler-jets.de/de/produkte/hst Now, my question is: How much thrust could you ...
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Can anyone identify this Biplane?

This Biplane from the 1930's is from an English Airshow. Can anyone identify it? There is now another picture.
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Why are prop blades not shaped like household fan blades?

My two projects right now are learning to fly and 3D modeling a replacement blade for antique fan, and a question occurred to me: Why are airplane propeller blades not shaped like household fan ...
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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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Can jet engines be used for VTOL civilian aircraft?

Why do almost all civilian VTOL aircraft existing today use propellers (or rotors) for take off and landing and not jet engines (as the Harrier does)? Is there a technical reason for this?
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What causes a run-away propeller?

I've never understood this, why can't you just idle the engine and let it slow down?
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ATPL - Principles of Flight - Question regarding propeller pitch

In my ATPL books i've learned that for a variable pitch propeller, it is better to have a fine pitch for take-off (higher RPM) and a coarse pitch for cruise (lower RPM). In this question taken from ...
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Must quadcopters have the same propeller sizes?

I was flying quads today and it just suddenly popped up into my mind — do the propellers all have to be the same size in quadcopters? Mine are, but What if two propellers were larger and the other two ...
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Why are helicopters less efficient than planes?

At higher speeds, advancing helicopter blades will operate at velocities approaching mach 1, reducing efficiency. But what about lower speeds? A helicopter is basically a wingless plane with a giant ...
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Are there any helicopter blades that fold in the middle?

Let's assume that, for some arbitrary reason, helicopter blades are too long for transport or storage. Folding them at the rotor hub, as is done with conventional folding helicopter blades, would ...
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How to estimate blade interference in a propeller or fan?

The ideal propeller has one blade. For obvious reasons, that would be impractical. However, adding more blades causes each blade to operate in each others slipstream/downwash. How to quantitatively ...
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Why do ground crews rotate a radial engine's propeller before a motor/cartridge start?

In footage from WWII you often see the ground crew rotating the propeller of a radial engine a number of times before the pilots start the engine. I know it's not the same as hand-starting (hand-...
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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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Why does RPM for a fixed-pitch propeller change with an aircraft's pitch?

Talking bout a C-152 - If I pitch the aircraft down, and without adjusting the throttle, the RPM would show an increase. Pitch up, and without adjusting the throttle, the RPM shows a decrease. I've ...
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What is the metal bit in the front of this propeller spinner?

What is that grey spirally bit in front of the propeller mounted on this Shvetsov ASh-62 radial engine?
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Why don't single propeller planes rotate around the horizontal axis? [duplicate]

According to Newton 3rd law, every action has reaction force in the opposite direction. That's how spaceship can move in space. That's why helicopter needs a second propeller in the back to prevent ...
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Is a propeller a wing?

An aviation expert claimed to me that a propeller is a wing. While I understand that propellers use similar principles to generate force, it muddied the definition of a rotary wing aircraft vs a ...
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What's the difference between a “runaway prop” and a “feathered prop”?

My father was a P-51 fighter pilot in WWII. Another P-51 flown by a buddy of his suffered a "runaway prop", and as a result of that, the plane could not maintain its normal high speed, and in the end, ...
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What are the relative efficiencies of the various stages of a counter rotating propeller?

After going through the CFD results of a drone project I am involved in, I noticed that the data shows significantly increased (+10%) thrust generation at the second stage of a counter-rotating, 2-...
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Are ducted fans more efficient?

As far as static thrust, does a shrouded/ducted propeller outperform an un-shrouded propeller? It seems that the guide blades on the bottom of the duct would allow little more thrust to be extracted ...
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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 open propellers experience pre-entry drag (additive drag) like an engine in nacelle?

Engines in a nacelle experience pre-entry (also called additive) drag. Do unducted propellers experience it too?
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Why are there so many different propeller shapes?

While doing an image search, I found these images of propellers: and Some appear to be straight-ish on the leading edge and curved on the trailing, some curved on the leading edge and straght-ish on ...
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Is it better to have the engines center or apart on a plane?

Are there any advantages or disadvantages to having the engines closer or farther to the center of the plane? How is the ideal engine spacing determined length or span wise for performance? Related: ...
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Is it more efficient to use inlet guide vanes or variable pitch blades

Again, its all in the question. two scenarios for a ducted prop in hover: inlet guide vanes close to the prop to control the angle of attack just a prop with a variable pitch mechanism. obviously, ...