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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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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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4answers
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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 push-propellers so rare, yet they are still around?

Jet engines are by their very nature push-engines, however, most propeller airplanes use pull-engines. Is there an inherent advantage to using pull-propellers except for the increased airflow over the ...
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Is it OK to move a light aircraft by pushing or pulling the propeller?

It's very common to see pilots moving a light aircraft by pushing or pulling on the prop, either because there's no tow bar available or simply out of preference or convenience. Is this a reasonable ...
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Why did the B-29 have so much leftward torque at take-off?

In this book, The Making of the Atomic Bomb by Richard Rhodes (p. 705), I read: [Paul Tibbets] eased the brakes [of Enola Gay] at 0245, the four fuel-injected Wright Cyclone engines pounding. “The ...
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Why do propeller blades not have winglets?

On the first look this question might sound ridiculous and maybe it is. But as propeller blades act by the same physical laws as wings, and winglets reduce the induced drag by quite a bit, then why ...
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How does a fan differ from a propeller?

Why is the fan in a turbofan different than a propeller in a small airplane? Why do propellers typically have 2 or 3 blades, but the fan has a lot more? And why is the fan shrouded but the propeller ...
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1answer
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How does a Constant Speed Propeller work?

My explanation of how a constant speed propeller works has always been a little shaky. I know about the "speeder spring," "counter-weights," and how it utilizes the engine oil pressure, but I'd love ...
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Why does flight training usually start with (unsafe?) propeller planes and not with (safer?) jets?

I live in the UK and would like to learn flying jets, but most courses seem to start with propeller planes. Not sure if this might be a misconception about the safety of different aircraft types, but ...
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Why would a turboprop rev down just before going full throttle during takeoff?

The only turbprop I've travelled is the ATR 72. I've noticed that the props' rev go down (for like a second, the sound also goes down) just before engaging full throttle in order to takeoff. I've ...
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4answers
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Do propeller planes give contrails like jets do?

Last weekend, while watching the second world war film "Fury" with a friend, there was a scene near the end with a large set of bombers flying overhead, leaving large contrails. That seemed wrong to ...
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Can a plane fly backward if its propeller is in reverse?

I would like to know if a prop plane, for example the P-51, could be able to fly backward. Is it possible through some trick like changing blade angle or reverse the prob rotation direction? It would ...
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Would connecting propeller blades with a continuous ring reduce induced drag?

Turbine engines are covered, which of course is to contain the process (just like a super/turbocharged engine is as soon as the air enters the intake). But it got me thinking, doesn't this also reduce ...
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4answers
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Why did WWII prop aircraft have colored prop tips?

Why do propeller aircraft from World War II and similar planes sometimes have the tips of the props colored? I see it on single engine planes like the P-51 as well as bigger, multi-engine planes such ...
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4answers
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Why do turbofan blade tips exceed the speed of sound while prop tips should not?

It seems that the tips of the fan of a turbofan engine can and do break the sound barrier: The GE-90 has a fan diameter of 3124 mm and a rotational speed of 3475 RPM. Their circumferential velocity ...
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6answers
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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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Can propeller driven aircraft sustain speeds at or above Mach 1?

Has any propeller driven aircraft ever achieved and sustained supersonic speed? If not, why can't propeller airplanes achieve that speed?
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1answer
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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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What are the pros and cons of scimitar propellers?

I know scimitar propellers are used to reduce noise, but what is their downside? There has to be one, considering most propellers don't use that shape.
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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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2answers
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What are the advantages of more than 4 propeller blades?

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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Would an aircraft with contra-rotating propellers longer than the plane's wingspan be able to fly?

I enjoy taking the time to try and visualize how fictional aircraft might actually work in reality. Unfortunately there are some that seem highly impractical from an engineering student's point of ...
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Why don't helicopter blades look like other propellers?

While doing an image search, I found many different shaped propellers and asked about them in this question. In it, Peter Kampf answered my question with his usual thoroughness. However, as I looked ...
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9answers
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In case of emergency, is it possible (doable) to land a small propeller-driven aircraft on an aircraft carrier?

I was watching the Disney movie Planes with my younger brother, and one of the characters/planes perform a emergency landing on an aircraft carrier. And that got me thinking... In case of emergency, ...
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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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Why do most single propellers have a clockwise rotation?

Why do most single propellers have a clockwise rotation (seen from the pilot's point of view)? There are though multi-engine planes that have each propeller rotating different directions, but in the ...
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2answers
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What are the advantages of the NASA LEAPTech propeller on wing technology?

NASA has detailed experiments with a new type of parallel array of small electric propellers on the leading edge of the wing technology that they are calling LEAPTech. The press release notes that ...
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4answers
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Are there design differences between propellers powered by air (wind-power) and propellers for aviation?

What is the difference of design between a propeller designed to be powered by the wind (i.e. those huge wind power turbine blades) and those designed to be used to propel a plane that are powered by ...
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2answers
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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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4answers
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Why are there extra restrictions on constant-speed propellers?

Constant-speed propellers are far more efficient than non-constant-speed propellers, allow the engine to be made considerably simpler (due to removing the need to continuously adjust the ignition ...
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1answer
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How high can propeller airplanes fly?

Is there a maximum height a propeller airplane could fly? Some lower bounds for maximum flying altitude: 12,000m (39,370ft): Antonow An-70, produced 1994 12,310m (40,387ft): Lockheed Martin C-130J ...
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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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2answers
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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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1answer
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Why don't aeroplanes use propellers with more blades like the intake on a fanjet?

The air intake on a fanjet typically has many small angled blades. A wind pump in an American film might have many broad slatted blades. My desk fan has 3 very large scooping blades and seems quite ...
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3answers
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What does feathering mean and how does it work technically?

Before I ask "What does Feathering mean when it comes to Jet/Propeller Engines" I have to say what I think I know: Feathering jet/prop engines mean achieving a sufficient turbine rotation speed at ...
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3answers
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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 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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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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4answers
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What is the propeller efficiency, $μ_p$, of modern propellers for light sport aircraft?

Roskam's book on preliminary design gives a value of 0.7 for "homebuilt" aircraft and 0.8 for general aviation. What explains this difference in propeller efficiency? The content of Roskam's book is ...
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1answer
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What's the difference between a two-blade prop and three-blade?

I read that a three blade can improve climb performance and decrease noise. How does that work?
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1answer
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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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Why are propeller airplanes still made?

Airplanes with propellers were invented a long time ago. After that, jet engines came into existence. My question is: why do we still have propeller engines? The reasons I can think of are: They are ...
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2answers
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Which way should I rotate the propeller of a C172?

During pre-flight which direction should I be rotating the propeller of a Cessna 172 if I need to reach the alternator belt? I thought I was told "In the direction it rotates during flight"; however ...
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1answer
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What operational differences were there in WWII for constant speed vs. fixed pitch propeller warbirds?

I have read about the operational differences between constant speed and fixed pitch propellers. Being a World War II buff, I was reminded of reading once about both principles being used in period ...
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Why don't planes have a reverse propeller as air brakes?

When I first heard the word air brakes it came to me that maybe the engine start rotating in the opposite direction for that, but since that's not possible, why can't we have an extra engine for air ...
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Why does the Cessna 172S Skyhawk use only two blade fixed pitched prop?

Surely it would get more thrust from a three blade variable pitch propeller. From what I've read it's all about the area swept and also should be far enough apart to not cause too much interference. ...
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6answers
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For an electric airplane are propellers the only option for propulsion?

This is for an electric airplane (so no fuels for combustion): Are propellers the only option? Is there a turbine-jet possible with only air intake, electrically compress, and a turbine and nozzle ...
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4answers
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How to execute a gear up landing on aircraft with low propeller?

On some GA aircraft such as the Piper Malibu, the propeller would touch the ground if the gear was up. How would you land the plane when gear actuators fail? I would pull out the mixture knob and ...
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Is the Progress D-27 really a propfan?

On WikiPedia, the Progress D-27 is described as a propfan engine and the airplane it powers, the Antonov An-70, is described as propfan-powered. This Air&Space magazine article contradicts that; ...