Questions tagged [propeller]

Aircraft propellers are airfoils which convert rotary motion from a piston or turbine engine into thrust suitable for propelling an aircraft.

Filter by
Sorted by
Tagged with
3
votes
2answers
1k views

Why does a low pitch propeller have better acceleration/take-off and climb characteristics than a high pitch propeller?

Why does a propeller with a low pitch have better acceleration/take-off and climb characteristics vs. a high pitch propeller? And conversely, why is a propeller with a high pitch not as good during a ...
13
votes
9answers
7k views

Were propeller airplanes significantly more “scary” to fly in compared to modern jet ones?

I've flown exactly once in my life. It was in 2004, with a commercial jet. Not a "jumbo", but a normal-sized jet plane in common use for cheap flights in that year. (Well, twice if you ...
10
votes
1answer
2k views

How do witness marks on propeller blades provide data on estimated blade angles at the time of impact?

In the NTSB Powerplant Group Chairman Factual Report for the 2014 crash of the King Air B200 in Wichita Kansas (NTSB# CEN15FA034), I read: "Neither propeller was feathered before impact. Both ...
1
vote
0answers
53 views

Calculating the Thrust vs RPM Relationship of a Brushless DC Motor

hope everyone is doing okay. I am conducting a project with my friends for an Unmanned Aerial Vehicle. We are first using MATLAB - Simulink to design and simulate the quadrotor. We completed the ...
0
votes
1answer
106 views

What is the certification process for a new propeller blade design?

I am wondering whether a propeller blade design (say from Hatzell) is submitted to a specific agency for testing and approval, and if these designs are then registered. Looking through Hatzell's ...
0
votes
2answers
120 views

In constant speed propeller, if i increase RPM lever from 2300 to 2500, will the Blade AOA decrease?

Assume I am flying straight and level with power setting 21 inches of MAP and 2300 RPM with TAS=100 kts, now I change my Prop lever only (MAP = no change & TAS = no change) from 2300 to 2500, ...
9
votes
1answer
1k views

What are the black boots on this Extra 300's prop?

I normally think of black boots on a prop as being for de-icing. However, the Extra 300 is not suitable for known-icing conditions, or even IMC flight. (It's AFM says "Only VFR flights at day are ...
0
votes
0answers
38 views

Is pitch-flap coupling an aerodynamic effect or an intrinsic property of a delta 3 offset?

I am modelling a propeller, in particularly the equations of motion of the various pitch/lag/flap angles as the propeller is turning around. The blade includes a $\delta_3$ angle, which provides pitch-...
2
votes
2answers
162 views

Why does propeller slip (efficiency) change during the flight (fixed-pitch)?

I was wondering how the efficiency of a fixed-pitch propeller changes during different stages of flight and why it does so. I suppose when we are talking about propeller efficiency we are actually ...
0
votes
1answer
56 views

How to decide the diameter of a propeller and number of propellers needed in a UAV I am designing? [closed]

I want to design a turboprop aircraft. I know all the design parameters such as lift, thrust, weight etc at a given flight stage. I want to know what the size of the propeller should be.
3
votes
2answers
158 views

How do electric propeller governors (or electrically controlled governors) work and what are their pros and cons?

I am trying to understand why electric propeller governors are not (yet) prevalent given that they offer the ability to control the RPM with high accuracy. What is the typical architecture for an ...
2
votes
0answers
67 views

Calculate propeller efficiency [closed]

I have a test bench that can test the thrust of a propeller with my electric motor, is there a way that I can calculate the propeller efficiency (ηp)?
6
votes
1answer
2k views

Why do propellors have white markings on their tips? [duplicate]

Why do propellors have white markings on their tips? Here are a couple of examples:
3
votes
3answers
245 views

Would it be beneficial to have rotors AND propellers instead of a tiltrotor?

Would it be beneficial for tiltrotor aircraft if they had BOTH rotors and propellers, instead of the hybrid proprotors that are neither good propellers nor good rotors? Like imagine the V-22 Osprey ...
-3
votes
1answer
151 views

Fly a fixed wing single propeller airplane like a helicopter?

Has anyone tried to "helicopter" an airplane? And succeeded? And posted this video on the internet where I can find it? What I'm talking about with what I would call a "helicopter&...
1
vote
1answer
145 views

What is the difference between RTOP, MTOP, and MCP?

I am currently learning how to fly the SD3-60 (Shorts) Aircraft, and I am trying to gain an understanding of RTOP (reserved take off power), MTOP (max take off power), and MCP (max continuous power). ...
1
vote
1answer
70 views

Retreating Blade Stall, P-Factor, and Gyroscopic Precession

Most airplane pilots are aware of P-Factor in propeller driven aircraft and that it tends create a torque in phase with the lift imbalance over the blade disc, resulting in a yaw moment about the ...
2
votes
2answers
179 views

What are the pros and cons of putting a propeller immediately before a slipstream pylon vs. immediately after

In the following situation with a slipstream pylon for a self-launching glider, what are the tradeoffs in sticking the propeller before vs. after the pylon? The wind turbine industry has the same ...
0
votes
0answers
34 views

Comparison of specific thrust vs. speed, for EDFs and propellers

I stumbled upon this graph showing the decrease in specific thrust (Thrust by Power) in relation to velocity, for a Schuebeler EDF: https://www.researchgate.net/figure/Specific-thrust-T-P-vs-airspeed-...
11
votes
3answers
3k views

Is possible to stick two '2-blade' propellers to get multi-blade propeller?

Does propeller blades' airflow interfere with each other blades and decrease overall thrust? Should I consider high pitch propeller for this purpose? My purpose: I'm looking for a 20-inch four-blade ...
9
votes
4answers
2k views

If an elliptically-shaped aerofoil gives the optimum lift distribution, why aren't propeller blades designed around this ideal?

So given an elliptical lift distribution is the most efficient, why are propellers not designed around this? Props aren't affected by the adverse stall characteristics that concern a "main", ...
1
vote
1answer
98 views

For a same propeller solidity, what are the tradeoffs between blade activity factor and blade number?

In order to absorb more power for a given prop diameter, we can design the propeller with a higher activity factor-- basically what amounts to wider blades-- or we can also design it with more blades. ...
2
votes
1answer
270 views

What is the result of increasing number of propeller blades on the same engine [duplicate]

For example Rotax 912. We can meet this engine with 2 and 3 propellers mounted. Or compare airplanes equipped with engines with pretty the same power output i.e. C152 with Lycoming O-235 - 110 HP and ...
1
vote
1answer
85 views

Deicing Rod for Propellers

Similar to a card hitting the spokes of a bicycle, the card is soft enough to knock the dust off the spokes with no damage. What material would be best to impede the propellers to chip off the ice. ...
0
votes
1answer
183 views

Why does a force on a propeller act 90° “ahead” due to gyroscopic precession?

This is a common explanation: A tailwheel airplane is on the takeoff roll and the tail comes up, the propeller disc rotates forward. That's akin to someone pushing on the top of the disc. The force ...
2
votes
2answers
376 views

Does a constant speed prop maintain the optimal angle of attack at all time?

From an answer on this site: The governor just knows: Speed too fast, flyweights move out, routes pressure to move the blades more coarse; speed too slow, flyweights move in, routes pressure to move ...
2
votes
2answers
128 views

How would flow angle change along the length of a propeller airfoil?

Let's assume I have: windspeed of 15 m/s blade length of 10 m rotational speed of one revolution per second Can someone please help me calculating how the flow angle would change along the length of ...
4
votes
2answers
149 views

How does one choose the number of blades and the diameter required for a turboprop propeller?

I am interested in the preliminary design of a regional aircraft that uses turboprops as the propulsion method. Following considerable research online about propeller design (disk theory, BEM...) I am ...
-1
votes
2answers
132 views

What is the physical difference between an airplane having let's say 150 horsepower to an airplane having 250 horsepower?

I was wondering what defines horsepower in an airplane piston engine and how can it be changed?, is horsepower changing during flight?
0
votes
1answer
90 views

How to do blade element momentum theory analysis for different geometries of airfoil, e.g. NACA airfoils?

I want to analyse NACA airfoils using BEMT. I have only yet done it for basic symmetric airfoils. I would like to know what all assumptions remain same in NACA airfoil analysis and to what degree it ...
2
votes
3answers
158 views

Is high propeller pitch inherently inefficient?

For an airfoil, in general, the aerodynamic force is more or less perpendicular to the chord line. A low-pitched propeller blade has it's chord line more perpendicular to the direction of flight, ...
0
votes
1answer
178 views

Would large, low aspect ratio fan/propeller blades be more efficient? Why not?

With reference to this answer We read in the above that accelerating a larger mass of air by a smaller amount is (theoretically) more efficient. This is an advantage of a larger propeller than is ...
0
votes
1answer
95 views

Help in understanding this velocity triangle of a propeller

I was reading a research paper and have had difficulty understanding something. How did the author get tan(phi) in these terms? This is something I've been trying to figure out for a long time now.
1
vote
0answers
51 views

Relationship of propeller RPM, blade pitch, and drag at very low blade pitch angles

I'm researching the 2016 crash of a PIA ATR-42 in Pakistan, the report on which was recently released. Link to the report: https://www.caapakistan.com.pk/Upload/SIBReports/AAIB-386.pdf During the ...
12
votes
7answers
3k views

How much do propellers stutter?

A photo in EAA's monthly magazine shows one propeller blade as a dozen distinct images rather than the usual smooth motion blur. One explanation (this answer appears to have been deleted) for this is ...
1
vote
2answers
72 views

Will the blade angle of a constant speed propeller be at its least angle (fine pitch) during full throttle and prop full?

During low power settings, low throttle setting and prop full during taxi, the blade angle will be at its finest pitch. As we increase the throttle for take-off, will the blade angle remain in its ...
-1
votes
2answers
127 views

What is a typical compression ratio in light turboprop aircraft propellers? [closed]

Does anyone happen to know a rough estimate of a typical light turboprop aircraft propeller's compression ratio? Something with 6-12 seats like a Cessna Caravan or Piper Malibu. Doesn't need to be ...
0
votes
0answers
58 views

Why does a shrouded propeller have a lower downstream velocity than an unshouded propeller?

Why does a shrouded propeller have downstream velocity $V_3 = V_0 + w$, while the unshrouded propeller has a velocity $V_3 = V_0 + 2 w$? What are the reasons of this difference? $ \begin{align} w &...
1
vote
3answers
180 views

How can I find the maximum climb angle of a propeller driven aircraft from a graph of vertical velocity against airspeed?

I've been asked to find the maximum climb angle of a propeller driven aircraft from the graph of vertical velocity against airspeed: How can I do that?
0
votes
1answer
129 views

Why aren't thermal analysis of propeller done?

I have searched for articles on Thermal Analysis of Propeller but couldn't find one. Can I assume the aircraft company don't perform heat transfer simulation and analysis of high speed propeller? Isn'...
5
votes
6answers
1k views

What other advantage(s) does an adjustable prop give you?

From what I understand, the purpose of a variable-pitch propeller (be it manually adjustable, or constant speed) is that it allows the engine to always operate at its most efficient speed, much like ...
9
votes
5answers
4k views

Do jet aircraft have a better glide ratio than propeller aircraft in general? If so, why?

Being fond of aviation, I play with software simulators a lot. I have noticed that while jets seem to be able to glide for a long distance even at zero throttle, propeller aircraft need to be ...
1
vote
1answer
146 views

How can a small ducted fan produce a large amount of thrust?

This 15.2 cm ducted fan by Schuebeler can produce 175 Newtons of static thrust. How is this possible in such a small diameter? If this seems normal, then why and how can this ducted fan produce that ...
0
votes
1answer
275 views

What factors determine magnitude and orientation of induced velocity at propeller blade?

• Magnitude What factors determine magnitude of "Vind" (induced velocity)? • Orientation If we take analogy with induced velocity at wing,isnt "Vind" must be prependicular to Vr? • ...
1
vote
0answers
109 views

Is “V/n” geometric or effective pitch in advance ratio formula?

V is the freestream fluid velocity, typically the true airspeed of the aircraft or the water speed of the vessel n is the rotational speed of the propeller in revolutions per unit of time D is ...
1
vote
1answer
127 views

Is flow attached at fixed propeller blade at every RPM / speed conditions?

Propeller blade AoA depends on tangential veloctiy caused by rotation and forward speed "head wind". If propeller has fixed pitch is flow attached on blade at every RPM / speed conditions? ...
0
votes
2answers
702 views

What is engine power vs propeller thrust relation?

Given: speed 30 knots engine power 70 hp at 5800 RPM propeller 3 blades, diameter 14 inch, pitch 17 inch, at 2300 RPM fluid density 1023 kg/m3 I know that each blade is basically one wing. ...
0
votes
1answer
163 views

Does ducted fan require more engine torque than unducted-fan,at same RPM?

Two identical fans, one is unducted and other is ducted,both operate at same RPM. •Does ducted fan require more engine torque than unducted-fan ,measured both at same fan RPM? power=torque x RPM so ...
0
votes
0answers
22 views

In actuator disk theory, why does changing the inertial reference frame work for Bernoulli's equation?

I was reading this website: https://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node86.html, which goes over actuator disk theory, and it discusses using Bernoulli's equation in a frame of ...
12
votes
5answers
5k views

Could propeller wash provide sufficient lift to take off - even in theory?

I know this seems a crazy thing to ask but it is not the same as lifting oneself by the bootstraps. If you try to lift yourself that way, there are two equal and opposite forces, yet there are ...

1
2 3 4 5
9