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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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3answers
1k views

Hand propping Cessna 172N, with a pilot and a non intuned passenger

Does anybody know what is the most effective way of hand propping a Cessna 172N, with a passenger who is not mechanically inclined. So you need to give them the most easy to follow and simple ...
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43 views

What is the effect of moving a propeller closer to a wing?

Does it improve efficiency? What if the wing is just a plate? Certainly increasing plate thickness will decrease efficiency.
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1answer
66 views

Can someone please tell me all the units for the propeller thrust equations?

This answer is excellent:- Is there any equation to bind velocity, thrust and power? except that it is (in practice) unusable, since all the units are missing. I'm guessing we use meters for length ...
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1answer
82 views

Which type of fan is better for wind tunnel testing?

I would like to build a small wind tunnel to test a miniaturized wing/airplane. I have two options, using axial blower (picture 1) or using centrifugal blower (picture 2). The first will be the wind ...
4
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2answers
291 views

Why aren't large, low-speed propellers widely used?

I am trying to calculate different propellers for the simple case like helicopter moving slow up like 1 m/s or staying/hanging in one place. From generic physics point of view it is more efficient to ...
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0answers
36 views

What is a good and simple software for calculating propeller thrust and required power?

My main requirements: Calculate propeller thrust with big range of the altitudes (0 - 200 km) or to have air pressure input parameter, which I can type. For example pressure for 152 km is $4.98\...
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3answers
409 views

What is the purpose of the propeller?

The propeller generates thrust, but what is the purpose of thrust of propeller? Is it to help the aircraft move forward or to produce lift to rise up?
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1answer
62 views

Which is better: a rotor / prop followed by a stator, or contra rotating rotors / props?

It is all in the title. I'm interested in power absorbed/used for a given thrust, or thrust generated for a given power (same diameters of course). Just thrust and power. Ignore materials, electric ...
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1answer
142 views

Do ducted fans have a future in forward flight aircraft? Can they be made more efficient than open rotors?

I'm fascinated by how ducted fans have the ability to be more efficient than open propellers of equal diameter in vertical flight through the use of tight tolerances, lightweight duct material, proper ...
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2answers
165 views

Would shutting down the engine have prevented the Atlantic Southeast Airlines Flight 2311 crash?

In the crash of Atlantic Southeast Airlines Flight 2311, a worn propeller quill caused the propeller blades to go flat, which created enough drag on that side of the airplane to make the aircraft ...
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1answer
66 views

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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1answer
83 views

What is aerodynamic 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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2answers
183 views

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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3answers
343 views

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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1answer
141 views

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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0answers
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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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1answer
107 views

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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2answers
247 views

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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0answers
63 views

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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2answers
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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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7answers
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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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3answers
927 views

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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2answers
207 views

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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0answers
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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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1answer
4k views

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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0answers
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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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2answers
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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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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, ...
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3answers
221 views

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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1answer
290 views

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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3answers
648 views

Would a Chinook helicopter fly better with contra-rotating along with counter-rotating propellers?

Would a Chinook perform better or have any advantage with dual contra-rotating propellers over a Chinook with just normal counter-rotating propellers?
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2answers
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Why would a propeller have blades of different lengths?

The Schempp-Hirth Duo Discus T powered glider has a five-bladed propeller, with blades of different lengths. What is the purpose of such an arrangement?
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3answers
167 views

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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1answer
76 views

Is there any equation on propeller thrust that takes into account the number of blades [duplicate]

I had a look at both What is the equation for calculating static thrust? and Is there any equation to bind velocity, thrust and power? However, it does not mention how much would the thrust be ...
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3answers
200 views

Does propwash increase pitch stability?

Here is a polar for a piston single-engine aircraft: (This is lifted from a Russian manual for Yak-52, so $C_x$ is drag, $C_D$, and $C_y$ is lift, $C_L$). 1 is the 'normal' case without propwash. 2 ...
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What kind of propellers are generally mounted on the Aeriane Sirocco?

I'm curious what propeller is used for the Aeriana Sirocco. Online I see lots of pictures of propellers with three blades, but none with only two and I cannot find many clear pictures of the proppeler....
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1answer
68 views

Propeller effect on the L/D of an aircraft (Pusher Propeller configuration)

I recently performed an aerodynamic analysis of a fixed-wing UAV with a pusher propeller configuration. I found out that the L/D reduced by about 15% when compared to the body alone without propeller. ...
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4answers
390 views

On a constant speed propeller, how is blade pitch related to airspeed and efficiency?

I'm trying to wrap my head around what the PHAK (Pilot's Handbook of Aeronautical Knowledge from the FAA) states for constant speed propellers. First, why is it that if airspeed increases, for a ...
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4answers
195 views

Constant speed propeller blade pitch compared to fixed-pitch

I just transitioned to a complex airplane (Piper Arrow II). While I get how to use the Manifold Pressure / Propeller levers, I still find myself trying to piece together how all the components would ...
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1answer
100 views

How do I calculate the total cruise power from the propelers accounting for the losses?

Let's say I have an aircraft with four propellers (see diagram below) and I am supposed to calculate the cruise power required to drive the aircraft forward. The wing creates the lift and propellers ...
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9answers
5k views

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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2answers
171 views

Will creating a strong back pressure within a ducted propeller enable an aircraft to attain a higher altitude?

I would like to know if creating a strong back pressure within a propeller duct will enable an aircraft to attain a higher altitude. Please reference the conceptual drawing below. This is showing a ...
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1answer
82 views

Would turbine blade twist change if all conditions except the density of the fluid remained the same?

While designing a turbine, the blade twist is apparent from the velocity triangles, and this analysis only depends on the velocity. However, would there be any difference for different media? When ...
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1answer
123 views

How heavy are turbofan and turboprop propeller blades?

How heavy are the blades from Turbofan (CFM56-5B, RRTrent800, PW4062A) and Turboprop (PW127M) engines? Is there a general appromixation like $$ m_\mathrm{Fan} = 0.1 \times m_\mathrm{Turbine} $$ ...
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1answer
113 views

What rotors would be best for atmospheric reentry?

What rotor blade set up would be the best for entering Earth atmosphere or to shed speed before landing in place of a parachute? I understand that the longer blades are more efficient, but are not as ...
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0answers
58 views

What is the relation between solidity and lift coefficients?

I've seen this graph in a couple of places. I'm not sure what it's supposed to mean, as the formulae I've seen in the papers cannot be found in any standard book or reference. Please let me know if ...
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2answers
10k views

What helicopter has the most rotor blades?

I have seen 2 rotor blades up to many and wonder when does having more rotor blades become less efficient? What helicopter has the most rotor blades? Related: Why don't helicopters prefer shorter ...
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1answer
1k views

Difference between constant speed and variable pitch propellers?

Here is how I currently understand constant speed and variable pitch propellers. In constant speed propellers, the pilot controls the governor via the prop control knob and the speeder spring, ...
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0answers
56 views

How accurate is blade element theory?

for a ducted fan/propeller, how accurate is BET? does it overpredict the thrust and underpredictes the torque? in other words, the power absorbed. if so, by what percentage approximately?10%?15%?
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1answer
128 views

Quadcopter: would putting 3 blades on the same level and the other blade below the first three work?

Most quadcopters have their propeller blades all on the same level, or in some cases, a pair of blades placed a little above the other pair. However, I was wondering if three propellers of a ...