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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3 votes
2 answers
7k views

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 ...
0 votes
0 answers
23 views

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
3 votes
2 answers
211 views

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
0 answers
54 views

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 ...
2 votes
1 answer
71 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 ...
3 votes
4 answers
520 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 ...
3 votes
1 answer
92 views

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
3 answers
2k views

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 ...
2 votes
1 answer
160 views

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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2 answers
199 views

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 ...
9 votes
2 answers
754 views

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 ...
0 votes
1 answer
81 views

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 ...
2 votes
2 answers
8k views

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 ...
0 votes
1 answer
133 views

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 ...
2 votes
5 answers
354 views

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, ...
-1 votes
1 answer
318 views

What velocity is used to calculate maximum range and maximum endurance?

These are my data; $C_{L_0} = 0.4$ $C_{L_{\alpha}} = 5.7$ $C_{L_{minD}} = 0.14$ $C_{D_{min}} = 0.022$ $k = 0.035$ $\alpha_{stall} = 15$ $S_{ref} = 20m^2$ Mass Data $W_{total} = 2500 \text{ kg}$ $W_{...
1 vote
1 answer
80 views

XRotor blade angle distribution

My question is about the XRotor definition of the blade angle distribution (beta), which XRotor solves for or requires as input. Is the blade angle on XRotor defined as the angle between the rotation ...
7 votes
2 answers
664 views

What is the difference in performance between variable pitch prop and two fixed propellers for take-off and cruise speeds?

Push-pull configuration aircrafts usually feature identical engines and propellers working only in tandem for multiple reasons like higher speed, better climb rate, reliability, cost, ease of ...
5 votes
4 answers
5k views

Did WW2-era aircraft have constant-speed or variable-pitch props?

This is slightly related to my other question on variable-pitch controls. I want to know if WW2-era aircraft typically had variable-pitch or constant-speed propellers. Variable-pitch lets the pilot ...
2 votes
1 answer
122 views

Do full-feathering constant-speed propellers have a high-pitch stop for the prop governor?

On full-feathering (hydraulic) constant speed propellers in general, and specifically Hartzell and McCauley props, does the propeller governor have a high-pitch stop (like non-feathering propellers, ...
54 votes
12 answers
122k views

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 ...
1 vote
4 answers
198 views

Should I advance my propeller lever forward during a glide?

I am reading the FAA Airplane Flying Handbook, chapter 3. It says: To enter a glide, the pilot should close the throttle and, if equipped, advance the propeller lever forward. (...) Why do we ...
3 votes
3 answers
512 views

Cause of Drag From Windmilling

I know that when a propeller is windmilling it creates drag, I assume this is from the propeller being flat against the air causes drag, but propellers are designed to essentially pull an airplane ...
2 votes
1 answer
210 views

What would have been the pitch angle of this McCauley Prop before impact?

I'm trying to determine the pre-impact pitch of a two blade McCauley variable pitch on a Cessna 210 that hit shallow ocean water (8 feet, mostly sand) shortly after takeoff from an altitude of 300 ...
2 votes
1 answer
192 views

Can a propeller with 90° pitching and symmetrical airfoils generate thrust?

Imagine we have a plane that is already moving at a speed $v_{plane}$. At a certain time $t=0$, a motor starts moving a propeller whose blades consist on symmetrical airfoils with $90^\circ$ of ...
2 votes
1 answer
173 views

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 ...
32 votes
2 answers
43k views

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 ...
24 votes
4 answers
20k views

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?
2 votes
2 answers
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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
2 answers
135 views

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 ...
8 votes
4 answers
4k views

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 ...
8 votes
1 answer
952 views

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 ...
6 votes
1 answer
254 views

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 ...
3 votes
1 answer
1k 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 ...
14 votes
1 answer
2k views

What is this indication on most turboprops?

What is the small fan I've seen on different turboprops?
6 votes
1 answer
175 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 ...
19 votes
11 answers
14k 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 ...
19 votes
3 answers
39k views

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 ...
9 votes
3 answers
2k views

Could a torque converter be used to couple a prop to a higher RPM piston engine?

Every RPM reduction gearbox I look at seems to have more parts in it than a Swiss watch. Great for keeping time but many parts to wear and breakdown. What seems especially worrisome is the direct ...
40 votes
8 answers
12k views

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 ...
0 votes
1 answer
471 views

Why would the tip of a propeller stall if geometric pitch was the same throughout the length of the propeller?

I can't seem to understand this sentence from the FAA PHAK about why propellers are "twisted." "If the blades had the same geometric pitch throughout their lengths, at cruise speed the ...
1 vote
1 answer
544 views

How to know what kinds of airfoil being used in a commercial propeller?

Suppose we know the 3D CAD model of a commercial propeller. Starting from that, we do the slicing to get the profile of airfoil being used to generate the complete shape of the propeller. How do we ...
3 votes
2 answers
751 views

Why are aircraft piston engines are so low rpm lazy engines?

I understand that the propeller speed should not be too much otherwise it will stall at the tip and be useless so higher rpm engine would be useless when we first think about it. However, we can put a ...
0 votes
1 answer
81 views

Stall on low airspeed with high power on right-turning propeller

Q: The pilot of an aeroplane with a single engine and right-turning propeller (clockwise from the pilot’s viewpoint) decides to go around. The pilot raises the nose too much as the power increases and ...
2 votes
2 answers
137 views

Torque and engine torque after aplying prandtl tip loss factor

I have a question regards to the following formula related to Blade Element Momentum theory for the application to calculate on airplane propellers: $$ dQ=4\pi r^3 \rho V_\infty(1+a) a' \Omega F dr ...
6 votes
2 answers
4k views

Why don't contra-rotating propeller configurations with more than two propellers exist?

I wasn't able to find a single example of more than two propellers stacked axially in a contra-rotating configuration. There is a huge number of contra-rotating propeller setups, but it is always a ...
16 votes
3 answers
42k views

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 ...
18 votes
4 answers
9k views

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 ...
7 votes
3 answers
538 views

What would happen if the blades of a variable pitch prop did not all have the same pitch?

What would happen if one or more of the blades (but not all) on a variable pitch prop would not tilt at the same angle as the other ones? Could this situation happen or is the technology so advanced ...

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