Questions tagged [thrust]
Questions about the propulsive force of a powered aircraft.
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Is contact between flow and inner walls of nozzle required for thrust generation?
I uploaded a picture below explaining over-expanded flow/nozzle condition with regards to thrust.
This aviation source tells that “extra nozzle walls don’t generate any additional thrust because flow ...
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If a jetliner is giving TOGA thrust but never releases the (parking) brake, will the brakes heat up?
From my - admittedly - limited knowledge of physics, the energy generated from the engines needs to go somewhere; will it go into the brakes or does it just dissipate into the air?
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optimal airplane propeller placement along the vertical axis?
is there a guideline for optimizing flight based on where the engine/propeller is placed along the vertical axis? some planes have the propellers well below the wings, some on the wings, some above ...
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Where is the thrust of a turbojet felt? [duplicate]
At a high level, this is simple. Hot gas goes out the back, and Newton's third law says the engine is pushed forwards. But when you look inside the engine, it's less clear which part experiences the ...
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How to determine thrust and power requirements from take-off ground roll distance?
I'm working on a project which requires me to determine the power requirements of a propulsion system from a specific take-off distance. Starting with this equation:
$$
s_g\approx \frac{1.21(W/S)}{...
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What is the GE90-115b turbine power output in horsepower?
The GE90-115b is rated at 513 kN maximum thrust and is often said to have 110,000 shaft horsepower, but I have yet to find any document or specification that backs the claim on horsepower figure.
A ...
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How does a fan in a turbofan engine suck air in?
I watched lots of video related to sucking process of a fan in a turbofan engine, but I'm confused at a point.
In this link and many videos like this, I found the fan'...
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Helicopter total power required: zero wind speed while climbing --vs-- down wind speed while hovering
I've been stumped on this for a while. Let's say you have a helicopter in climb mode (i.e., 100 ft/min) with zero wind speed present. Would the total power requirement be the same as if the helicopter ...
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Why is thrust (in a high bypass turbofan for e.g.) non-linear with respect to N1?
I've been studying jet engines for a short while now and I think I have a pretty decent understanding of how thrust is generated, but one thing I'm struggling a bit with is how thrust varies across ...
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How does the line of thrust affect longitudinal stability?
I’ve been studying Pilots Handbook of Aeronautical Knowledge FAA-H-8083-25B and on p 5-17 they talk about thrust line and stability. Can someone explain why the moment changes when thrust is applied?
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Does thrust output in jet airplane remains constant when altitude increases?
I’m a noob so sorry for my ignorance. The question is: do we need (in jet airplane) to increase the throttle to maintain constant thrust output if we want to fly higher (not considering climb phase), ...
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How can I calculate the thrust of a propeller?
I am working on designing a paramotor, and need to calculate estimated thrust for the propeller. Is there a calculator or equation where I can input a diameter, pitch and rpm and get a ballpark thrust ...
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If the pitch of a bypass fan blade in a turbofan is fixed how does it manage to provide thrust over such a large speed range?
A fixed pitch propeller is only good for aircraft that do around 100kts because the angle of attack on the propeller decreases as the forward airspeed of the aircraft increases, limiting the thrust ...
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Would the dle 55ra engine be enough to power my paramotor(ducted fan)?
I plan on using the dle 55ra engine to produce 5hp at 8,500 rpm. I am using it in a paramotor, and to save space I am considering using a ducted propeller similar to the Fulcrum power pod. The duct ...
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How much horsepower do I need for my paramotor?
Assuming my full kit and I weigh 82kg total, I have estimated that I need 5hp. To calculate this, I used the formula:
weight force (W) is F = m g
W= 82kg*9.8 ms/2 =401.8 Newtons
Now, if the drag ratio ...
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How much thrust should be applied when you set the autopilot to a specific altitude?
After a plane takes off the pilot usually sets the autopilot to the altitude of the flight level they are about to cruise at, e.g. 30,000 ft, right? When that is the case, how much thrust should be ...
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how does the lilium jet counter asymmetric thrust?
So Lilium states that its jet is a tailless design. Now, you can see that it has engines on both sides of the centerline.
Lets imagine that all of the engines on one side fail, how does it counter ...
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How can I calculate the TOTAL drag of the ENTIRE airplane?
I have an aircraft similar to a Cessna 172 and am using a virtual wind tunnel software (flowdesign) to get a drag estimate. I import the airplanes 3D model and I get around 2240 lbs of drag with a ...
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How do airplanes with thrust lines above CG still fly without a down pitch moment?
Mainly the Icon A5. I remember trying to make an RC aircraft similar to it, but the moment i'd spin up the motors the aircraft would understandably pitch down. i couldnt fly it at all.
So how do these ...
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What is the general mathematical relationship between increasing an airplane's weight and the needed thrust to fly?
I understand that increasing an aircraft's weight without changing any other properties means that its takeoff, stall and cruising speeds all increase since you need to generate additional lift. So ...
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How much thrust can a balloon generate with wings?
I have heard that some balloons have been made with wings, angled such that they generate some forward thrust during the ascent. Balloons can also theoretically generate thrust with wings during a ...
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What is the thrust balance between compressor and exhaust nozzle for a turbojet engine?
I had this question asked in university and the teacher was unable to provide more than a theoretical estimate. The ratio I was given was 15/85.
Obviously in the case of a turbofan this ratio ...
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Would a coaxial propeller with the second prop slower and larger improve speed?
Looking at various propeller designs, I started wondering about these limitations:
Large propellers at high speeds have tips going supersonic
Scimitar props attempt to keep prop tip from going ...
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Can Flex thrust be lower than climb thrust?
Let's restrict this question to airliners with 2 jet engines.
For the remaining of the question, I'll use the term flex to designate reduced take off thrust as I'm more familiar with airbus's systems....
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How can a turbofan's fan generate thrust in cruising flight if air is being slowed down?
High bypass turbofans in airliners generate most of their thrust from their fans, not their "cores". However, at cruise they are actually spilling some air past the intake rather than ...
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Electric ducted fan with thrust tube thrust and exit velocity calculation
I am working on an electric ducted fan rocket that has thrust vector control, see image 1. The 90mm EDF is located a bit higher above this blue section, near 1., so I believe the blue section becomes ...
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What is the thrust to weight ratio of the A330-900neo?
Does anyone know what the thrust-to-weight ratio is for the Airbus A330-900neo?
I'm getting different numbers when I try to calculate this for myself.
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static thrust vs. prop RPM data?
edit: question was too long, and is actually simple, so I removed unneccesary description
Background:
There are many questions here about:
propeller efficiency
changes to thrust when it is dynamic
...
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Why is the Cirrus Vision SF50's turbine angle so acute?
I saw a Cirrus Jet on the ramp and was struck by how much its engine points upwards. I can't recall having seen this kind of positive thrust angle, and so wondered what the explanation was.
A picture ...
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Why the greater the propeller slip is, the more thrust it generates?
Forgive my poor English skill and my entry-level understanding of aviation stuffs. I'm currently a student pilot.
As I understood, the propeller slip kind of represents the propeller efficiency in ...
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How is bleed air flow related to thrust level?
I read that the bleed flow negatively affects the thrust levels for a turbofan engine. However, I was wondering if vice-versa is true as well? Whenever the thrust levels for a turbofan are lowered at ...
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Power calculation of propeller
This is probably a very simple question, but I have been really struggling and need your help.
I have simulated a propeller with these parameters on Ansys:
Thrust: 2000 N
Angular Velocity: 314 rad/s
...
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Why do turboprops not have a thrust value in the specifications? [duplicate]
When looking through aircraft engine specifications, turbofans always provide a thrust value, e.g. in JT8D engine: https://prattwhitney.com/products-and-services/products/commercial-engines/jt8d
In ...
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Relation between lift force and torque produced in propeller used for vertical take-off and landing aircrafts
There are many answers for this question but none of them are specific.
I need to find the exact relation between the lift force of a propeller of specific pitch, attack angle , dimensions and ...
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What is meant by the pointing vector and pointing vector magnitude in ECI?
In Siouris's Missile Guidance and Control Systems, it is stated that the angle of attack can be approximated in a 3DoF (degrees of freedom) simulation by the following equation:
I know that ECI ...
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Why do pilots slowly give the plane more thrust during takeoff?
I have mostly seen pilots slowly pushing the throttle to toga during takeoff. But why? Why don't they just directly put the throttle to toga? Wouldn't that save runway length?
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What is the maximum Mach number that can be achieved at the exit of CD nozzle?
I understand that you can get Mach 1 at the throat of a convergent-divergent (CD) nozzle and after that you can have two roots, one is for subsonic and other is for supersonic.
Considering the ...
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What do you call a fall that is due to too little engine power, not due to cessation of aerodynamic lift?
If you raise your plane's pitch but the engines can no longer counter the gravity and you begin to fall (because the engines are too weak, not because of too little lift), what do you call that? This ...
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Is axial bearing in turbo fan,turbo jet engines neutraly loaded?
Is axial bearing in turbo fan,turbo jet engines neutraly loaded,if yes then turbine/fan and compresor produce eqaul and opposite force?
If yes ,where then thrust come from,at internal walls,must be ...
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What exactly is the pressure thrust component and why does it exist?
I'm teaching PowerPlants on a ATPL theory course and honestly have some trouble wrapping my head around this one:
Most literature describes the term "pressure thrust" – as opposed to "...
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Using a spring balance to find static EDF Thrust
I have been attempting to measure the static thrust of my EDF with a spring balance. It is part of a group university project. The EDF specs are as follows: 90mm freewing 9 blade 1900 Kv thats rated ...
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Why is thrust inverse to speed in piston engines?
It is said that piston engines have constant power output, and thus their thrust is inverse to speed (e.g. here), while turbines have relatively constant thrust. I'm looking for an intuitive ...
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How to calculate the efficiency of a rubber powered propeller
I made a simple test rig together with a stopwatch to measure the thrust (in grams) with respect to time of a rubber powered propeller. This enabled me to compare the performance of different ...
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What is the specific fuel consumption and cruise thrust of PW1521G engines?
I'm looking for the specific fuel consumption (SFC) and thrust related to PW1521G in cruise regime, as well as the associated assumptions for these ratings. I can't find them online.
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Is thrust larger than weight in a vertical climb?
Image source
Very much related to the many questions and great answers to lift and weight in a climb - if an F-16 climbs vertically at a constant speed, is thrust greater than weight?
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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 ...
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Can I check my density altitude with brake tension?
The same way one would apply the brake and accelerator, the more torque the more break is needed to hold the car, can a plane use this same technique to check the plane thrust and air density before ...
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Other than fighters, which airplanes can fly straight up?
I would think, for example, all modern fighter jets can maintain 90 degree climbs due to having thrust to weight ratio greater than one.
Are there any other air planes which can do that?
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Can a stopway withstand thrust of B737 engines on takeoff if the aircraft is lined up on the edge of the runway?
Can the thrust of Boeing 737-300 engines break the asphalt surface of a stopway marked with yellow chevrons? Can anyone give a documented reference?
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What is the approximate thrust at sea level for a C-130J Hercules?
I am looking for the approximate thrust of a C-130J Hercules under ISA sea level conditions. Also the efficiency of its propeller would be of help.
An answer to this question would really help my ...
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