# What is Propeller: Definition and 141 Discussions

A propeller is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral, that, when rotated, exerts linear thrust upon a working fluid, such as water or air. Propellers are used to pump fluid through a pipe or duct, or to create thrust to propel a boat through water or an aircraft through air. The blades are specially shaped so that their rotational motion through the fluid causes a pressure difference between the two surfaces of the blade by Bernoulli's principle which exerts force on the fluid. Most marine propellers are screw propellers with helical blades rotating on a propeller shaft with an approximately horizontal axis.

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1. ### I Wondering how much thrust a drone propeller generates

I was wondering how fast you would need to spin a drone propeller to lift x amount of force and mostly how the rpm of the propeller affects the force of the airflow it releases. I’m incredibly new to physics in general and you can take everything I say with a grain of salt. I have no actual...
2. ### Why does this refueling pod on Navy fighter jets have a propeller?

I was watching some videos of aircraft carrier cat shots of fighter jets today (don't ask), and was surprised to see in a slow-motion closeup shot that one of the underwing pods on an FA-18 had a propeller spinning on its nose. That seemed pretty strange to me, so I did some Google searching...
3. ### Max linear speed of propeller tip in water

Homework Statement:: project not homework Relevant Equations:: vectors Hi,I am trying to determine the maximum linear velocity of a propeller tip when subject to flowing water with velocity ##\vec V##. For simplicity, I will assume that rotational inertial is negligible. The drawing below...
4. ### Propeller with bell lift distribution has best thrust/power ratio?

This source http://sustainableaviation.org/sas2017/session/prandtl-wing-maximum-efficiency/index.html claims : "Bell lift distribution can be applied to propulsion systems (no more “minimum induced loss”). We believe this results in a gain of 15.4% thrust for the same input torque/power." Bell...
5. ### Propeller blade lift distribution for best thrust/power ratio?

What is ideal lift distribution for propeller blade to get best thrust/power ratio? To do this blade must has minimum drag, because drag releted to torque,and torque x RPM= power..
6. ### Turboprop engine propeller efficiency data

Hello, I'm looking for data on turboprop aircraft engine propeller efficiencies. I'm hoping for a table of available modern engines with a propeller efficiencies for comparison. I've tried Googling but not much luck. I can't even seem to find propeller efficiencies on the individual engine...
7. ### How much twist on a propeller?

I am 3d printing micro wind turbine blades (5-10 watts output in 30mph wind), but anyway I am using naca foil shape twisted to make it. This is not technically a propeller (cannot be efficiently used to push air) because it is generating power from moving air: it is a repeller, but regardless...
8. ### Propeller thrust with backwards air flow

The Blackbird wind powered car travels directly downwind faster than the wind speed powering it. Typically a 10 mph wind from directly behind it will cause it to travel at about 30mph. I am trying to analyse how the car accelerates from rest. I know how it travels faster than the wind speed so...
9. ### Design of Hydropowered Turbine Propeller for Mobile Charger

I am currently working on a project for an undergraduate course in university. My team and I have decided to make a hydropowered mobile device charger, and I am responsible for the design and modeling of the turbine propeller. This turbine will need to be able to function in low velocity streams...
10. ### Single and Dual-Rotating Propeller Question

Hoping that someone can explain what the optimum angular displacement between the front and rear propellers actually means here in the following paragraph. It concerns the single-rotation case of the experiment: "Both the eight-blade single- and dual-rotating propellers were mounted in four-way...
11. ### Thrust of a large ship's propeller accelerating the ship

Hello. Not sure how to even begin with this question honestly. Didn't learn anything about thrust regarding this topic so it got me dumbfounded. Here's how I try to interpret it: I'm assuming that the thrust created by propellers = net force of the ship, where I can use F=ma to find...
12. ### Could wing height position (through changing pitch) affect propeller airflow?

I am talking about low wing single engine WWII fighter types. In particular, I am interested in accelerated propeller airflow through the transition/curvature of the prop slipstream spiral distribution around the wing, from being partly below, towards mainly above the wing. This as the wing's...
13. ### Single Propeller load asymmetry in turns?

Single Propeller load asymmetry in turns Does this have a formula, and what is the current Flight Physics consensus of the effect of this on turns? G.
14. ### Fluid Mechanics: Momentum Equation Propeller Question

For this question, this is my working. The main issue is I cannot figure out where the factor of \frac{1}{2} comes from. So I consider a control volume right around the propeller (in the frame of reference of the propeller) and I apply R(-->) Force = Change in Momentum Flux F = \dot{m_{o}}...
15. ### Propeller - Rearward flow of air

Hi, Could someone please help me in understanding how the air is thrust rearward by a propeller? I am specifically interested in how an axial-flow compressor, which uses aerofoil shaped blades to force the air through the engine does so, however I feel a good start is a propeller. It makes...
16. ### Thrust required for a Car driven by a propeller

Out of curiosity, If suppose a car is driven/propelled by Propeller, how much thrust would be required to get it rolling or moving, then drive at 30 MPH, at 60 MPH and at 100 MPH? Consider the car weighs 6000 lb including passengers. If same car is inclined at 30 degrees, how much thrust is...
17. ### What is the Career of a Retired Chief Technologist in Servo/Mech R&D?

BSME Missouri University of Science and Technology (was University of MO at Rolla) '78 Retired after 32 year career in disk drives Chief Technologist managed about 150 electrical, mechanical and computer science engineers developing servo mechanics for hard disk drives Two boys, one graduating...
18. P

### Relating propeller thrust, power, and rpm together

Hi All, I am involved in a research project regarding electric aircraft. I've done a fair bit of research into this but am having trouble keeping all the different parameters and how they affect each other straight in my head. Fundamentally I am putting together a model whose parameters I can...
19. ### Can a Custom Radial Fan Lift a Human-Transporting VTOL Drone?

due to a design issue I'm trying to figur out whether i can get enough thrust to lift a 150-200 kg using some costume made radial fan instead of the usual propellers for a little vtol drone I'm willing to produce. any comment will be much appreciate. Thanks.
20. ### Pressure distribution for a ducted propeller

Rather than going off topic in a thread about inviscid fluid in a pipe, I decided to start a new thread. For this thread, I'm wondering about the effect of a ducted propeller operating in the air. Using this NASA article as a guide: https://www.grc.nasa.gov/WWW/K-12/airplane/propanl.html The...
21. ### Using a propeller to excavate sand under a boat

Good day. I want to use the boat's propeller to excavate sand. This will be done using a tube which will deflect the thrust downward. What are the implications? The boat is anchored. Thus there is zero forward speed. I suspect this may change the properties of the way the propeller functions...
22. ### B Propeller thrust in restricted air flow environment

looking at where to start understanding how the thrust/lift generated by a specific propeller (hypothetical one) changes as a function of surrounding air pressure. obviously the lift will go to zero as air pressure decreases. as pressure increases, modeled by say mounting the propeller inside...
23. ### Moment of Inertia of a Propeller?

Is there an equation for the moment of inertia of a propeller? If so, what is it? If there isn't one, can I use the moment of inertia of a rectangular slab? Thank you in advance.
24. ### Difference between a propeller and a fan

Good evening to all...I am troubling with a doubt that how a propeller differs from a fan regarding jet engines..
25. ### Accounting for Pressure Drop in Propeller Calculations

I'm trying to optimize a system involving one or more propellers / fans driving air through a packed bed for scrubbing (compressed then expanded) and out the other side to achieve propulsive thrust. So there's going to be a pressure drop in the slipstream. I've already set up a system to do the...
26. ### Rotational Dynamics Designing a Propeller Velocity/Acceleration

Homework Statement You are asked to design an airplane propleller to turn at 2400 rpm. The forward airspeed of the plane is to be 75.0 m/s, and the speed of the tips of the propeller blades through the air must not exceed 270 m/s. What is the maximum radius the propeller can have? With this...
27. ### Aircraft Propeller Blast velocity while in motion

I am working on a range extender for full size electric aircraft. It is a turbine located under the cowling, protruding only 8 inches. On my full size static model, the turbine can produce 600 watts with the prop blast v measuring 38 mph. If we could fly the plane (we can't, no wings) at 80...
28. ### Automotive Propeller powered car questions

I'm trying to build a propeller powered car. Right now I'm trying to find ways to make if faster because I'm limited to a 6 volt battery pack. I was wondering if I used a nozzle shaped design like they do for rockets if it will make it faster or slow it down. The propeller is 6 inches and I was...
29. ### I Marine Propeller Thrust: How Do I Calculate It?

Hello folks! I hope all of you are having a good day. Here is my question: How can I calculate the thrust needed by a marine propeller to move a body of about 120 kg? Also, as long we are talking about marine propeller, our propulsion is in water and not in air, so what about the rpm? Are they...
30. ### Power lost due to friction in a propeller

1. Homework Statement Calculate the power lost in friction in the system shown above, with d=0.36, rpm=200, u=0.72, prop=1m and oil=0.23mHomework Equations I know p=w/t comes into it in some form, either with other equations subbed in or a derivation somewhere, but not sure. The Attempt at a...
31. ### One big propeller vs. multiple smaller propellers....

The question is which is better from the efficiency point of view: One big propeller or multiple smaller ones? Or are they the same? My general impression is that a bigger one will have much more better efficiency as if you consider the following points: 1. lift is proportional to the area of...
32. ### Equilibrium velocity of a propeller-driven aircraft

Hi - I just want to know if I'm approaching this correctly. I'm trying to calculate the equilibrium velocity of a propeller-driven aircraft when supplied a given amount of power. I'm iterating: min_velocity = 0.01 max_velocity= 200 aircraft_velocity = 5 for i in range(steps): force = 0.5 *...
33. ### Propeller Weight & Number of Blades: Effects on Thrust

Does the weight of a propeller have any effect on the thrust provided? For example, if there are are two propellers of the same size same speed but different weight, would the one with more weight have a greater or lesser thrust? also would effect do the number of blades(faces) have on the way a...
34. ### B Relativistic tips of a propeller

Hi! Yes, I know that faster-than-light travel is impossible. But please stay with me for a while to help me understand this. Let's imagine we take some unobtainium and build a 12-km-radius propeller, attached to an engine able to accelerate it up to 250,000 rpm (like a turbocharger, or not a few...
35. ### Calculate Propeller RPM from Motor No Load RPM

Hello I am wondering what the relation between motor rpms and propeller rpms. I know that once you put the propeller on you are going to lose some of that speed due to drag and weight of the propeller. Spec. Battery: 10 Cell /37V RPM: 231kv Max current: 80A Watts: 2960w No load current...
36. ### Generating power with a propeller

Quite simple of a question: For the purposes of a competition, I need to design/create a propeller with the greatest capacity for producing power. For the sake of standardization, all propellers must be made from a CD. Of course, since this is a competition I cannot ask for help on the...
37. ### Maximum Thrust force in submarine

I am designing a submarine in low scale that the max propeller OD is 10 cm, means from center of shaft to propeller edge I have around 5 cm distance. I am trying to find the maximum thrust as this submarine suppose to pull an object inside water pipe. I need to find optimum rpm ,blade number...
38. ### Centrifugal Force load caused from propeller rotation

Is anyone interested in telling me the force created from 2 propeller blades rotating 2000 rpm.The total diameter of the prop is 72 inches and the weight of 1 blade is 4 lbs. Reason for the question is I want to mill a clark-y profile the length of the blade less ,4 inches for a bolted...
39. ### Hovercraft/Fan/Air compression

Hi I'm working on a project where I would need to lift about 400 pounds about 1 inch off the ground and keep the momentum in order to manually move it. I thought about using four fans with a skit on each corner facing downward to allow for upward movement, but I'm not sure how much power I would...
40. ### Selection of airfoil and sizing of propeller

Two problem to solve. 1) I have 4 propellers built with different airfoils. I have the graphs of coefficient of thrust and efficiency in function of advance ratio. There is a mathematical method to select which one is the best or the only way is just look at graphs 2)I know the maximum thrust...
41. ### What is a good power source for a personal flying machine?

Hello, I am trying to build a personal (one-manned) propulsion system that will allow individuals to fly above the trees, preferably fast, and for long amounts of time. I plan to do so using propellers. The power will need to be plentiful and long lasting. These are some options that I am...
42. ### Auto/Motor Building a mini physics motor boat -- Help?

Should the propeller rotate clockwise or counter-clockwise? Which way will be faster and will allow the boat to accelerate the fastest?
43. ### Calculating Propeller Thrust for Custom-Made Drone

I would like to know how does the general equation about propellers thrust look like. How should I calculate the force to be big enough for a lift off? The object (a drone) is located in a spacecraft , which means the gravitational force is 0. Are there more variables that I should concern...
44. ### Is propeller pitch more related to RPM than aircraft speed?

I'm reading about propellers and trying to get some of the basics, and some things are confusing to me. Namely, a quadcopter has a 12x6 prop, with a 6-pitch. That means in every rotation it should move 6 inches forward(up), but it doesn't do that at all since it's in hover mode. Wouldn't that...
45. ### Angular and linear velocity propeller

Homework Statement You are designing an airplane propeller that is to turn at 2400 rpm (Fig. 9.13a). The forward airspeed of the plane is to be 75m/s, and the speed of the tips of the propeller blades through the air must not exceed 270m/s. (This is about 80% of the speed of sound in air. If...
46. ### Optimum positioning of fan inside an enclosure

Hello! I am an electronics engineer and the only time I came across Fluid mechanics was in class 12. I have been stuck for a long time in the finalization of a product. The difficulty is that I need to design a heat-sink, place a fan over it and perform a thermo-fluid simulation of the system...
47. ### Similarities between propeller aircraft and jet aircraft?

I was thinking about the working principle of propeller aircraft (piston engined) during some dark night hours with nothing to do... Mostly because of flight simulator video games hahaha... Basically for the piston engined propeller aircraft (P-51 Mustang) to move forward, the propeller must be...
48. ### Propeller Speed and Stacked Plane Propellers

My background is electrical engineering, but I have a question regarding the mechanics and physics regarding plane propellers. The purpose of a plane propeller is meant to provide thrust to the plane. Similar to a plane wing, the propeller generates lift but does so in a direction that is...
49. ### Do the number of blades in a propeller matter?

I was really wondering if the number of blades in a propeller influenced the power it has, are too many blades bad also? At last I will like to know how much force will you need to elevate a person 1 meter over the ground an mantain the person at that height?
50. ### Can Helicopters Use Propellers Like Gyrocopters for Lift?

I have a doubt that instead of the rotor blades in the helicopter why can't we use a propeller for thrust producing