Questions tagged [thrust]

Questions about the propulsive force of a powered aircraft.

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5answers
388 views

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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0answers
82 views

Can a BLDC motor meant for a multi-rotor be used for a fixed-wing aircraft? [closed]

I am designing a propulsion system for a fixed wing aircraft (RC plane). I have found a motor that meets all the requirements of my fixed wing aircraft. But the motor was for a multi rotor. Can we use ...
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1answer
85 views

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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3answers
618 views

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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2answers
67 views

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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5answers
3k views

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 ...
4
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2answers
443 views

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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0answers
109 views

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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1answer
170 views

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,in image 1. The 90mm EDF is located abit higher above this blue section, near 1., so I believe the blue section becomes a ''...
3
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1answer
453 views

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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0answers
74 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 ...
2
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1answer
249 views

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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0answers
71 views

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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1answer
172 views

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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2answers
212 views

On a Boeing 737, can the APU, BY ITSELF, provide enough thrust to move the plane while on the ground? [duplicate]

There are numerous questions and answers about the ability of an APU to provide enough thrust to maintain flight. In contrast, my question is whether the APU, by itself, provides enough thrust to ...
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1answer
93 views

What thrust is used for thrust to weight ratio?

Performing some preliminary calculations for an aircraft design I have and was wondering what thrust I should use to calculate thrust to weight? The thrust calculations I have, vary due to speed (...
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1answer
83 views

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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0answers
38 views

Bleed air examples and percentages [duplicate]

I'm doing an assignment in GSP where I've got to examine bleed air and it's effect on thrust and fuel consumption. I've got to simulate 1-10% bleed air and then answer whether the drop in performance ...
-3
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1answer
143 views

What should be the thrust weight ratio for takeoff? [closed]

I am doing some calculations for preliminary design of an airplane and I was wondering how I would go about determining the minimum thrust to weight ratio needed for the aircraft to takeoff. Which ...
3
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2answers
473 views

Why is TOGA thrust 'never' 100% N1?

The title is voluntarily the opposite of this question: Why isn´t TOGA thrust always 100% N1 or N2?. I explain to you with an example: I'm looking to the FCOM of an A320 which states that the "...
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1answer
201 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). ...
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0answers
37 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-...
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3answers
202 views

Why do we take off with maximum power settings?

In most GA prop airplanes, take-off is executed with full throttle and high rpm. The usual reasoning is that this way, we leave the first few hundred feet, where failures are most severe, behind as ...
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2answers
111 views

This concerns the GE90X fanjet engine which generates 130,000 LBS of thrust at takeoff [duplicate]

This concerns the GE90X fanjet engine which generates 130,000 LBS of thrust at takeoff. But for this example the engine is secured to a test mount, and under "full throttle", the thrust ...
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0answers
33 views

How to calculate turbojet thrust at variable altitudes and mach numbers?

I am interested in developing a flight model in jbsim. jbsim requires a thrust table similar to as follows, with varying mach and altitude numbers (with thrust as a fraction of max): ...
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2answers
184 views

How much thrust is required for a Boeing 747 to "keep flying" at 4 km altitude?

Not full power, just enough to keep the plane moving at 4km altitude.
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6answers
560 views

Why can't you have sail-powered airplanes?

So, sailing boats take the kinetic energy of a crosswind and turn it into thrust by using their sails as lifting surfaces, and the discussion I had in the comment section of this question made me ...
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2answers
126 views

Can thrust be produced only using the forward speed of a nozzle?

Why can't a nozzle that is already in relative motion to the air produce thrust by speeding up the air that passes through inside it? So let's pretend you're in a glider with two converging nozzles (...
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2answers
210 views

Is Assumed Temperature used in conjunction with a Derate in the B737 NG?

When using an Assumed Temperature for Takeoff, is it common operational practice to also use a Derate?
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2answers
183 views

How does the aircraft keeps propelling forward when airflow and thrust are not aligned?

Assume an aircraft is flying at an angle of attack of 10 degrees, and that the incidence angle between the aircraft fuselage and the wing as well as the angle between the wing and the engine mount is ...
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2answers
181 views

What´s the logic behind the Power Curve?

Aircaft thrust is what counteracts drag, but in flight school they tought us that propeller aircraft are "power producers" and not thrust producers as jets. (That´s because the propeller ...
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1answer
859 views

How do power and thrust curves compare?

I would like to really understand why when talking about jets we care about thrust but when talking about propeller aircraft we care about power. (THRUST)="Just a force" (POWER)= work/time = ...
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1answer
310 views

Is Flight Idle a constant?

Is "Flight Idle" for a jet engine a constant N1% value or does it vary with Altitude, and OAT?
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1answer
253 views

Should "Thrust Reduction" and "Acceleration" heights be the same for the Boeing 737 NG?

Should the Thrust Reduction height be the same, lower or higher than the Acceleration Height? In other words, what is their "correct" sequence. I am referring specifically to the B737NG, if ...
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2answers
237 views

Is this the relationship between rpm and thrust of a Turbofan? [duplicate]

In this graph from the FAA Airplane Handbook Chapter 15, page 5: It looks like it is talking about "jet engines" but is it engine type specific or it is for both turbojet/fan/prop/shaft? It ...
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2answers
320 views

Why would sea level static thrust have a takeoff and a maximum continuous value?

In the type certificate data sheet for a jet engine, there is this table static thrust is the thrust generated by the engine when the plane is at rest with respect to the Earth and the surrounding ...
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1answer
387 views

Why is thrust said to be constant over speed for a jet engine?

I'm just interested in some basic facts regarding flight. On reading the rather "low level" book "Understanding Flight, David F. Anderson, Scott Eberhardt), I recently came up to the ...
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2answers
162 views

Is the well known textbook-formula for net-thrust oversimplified or do I have a misinterpretation?

In order to understand how Jet-Engines works I came across the "famous" formula for net-thrust: https://en.wikipedia.org/wiki/Turbojet#Net_thrust $F_{thrust} = Q_{out} \cdot v_{out} - Q_{in}\...
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1answer
155 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 ...
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2answers
236 views

How does altitude affect the TAS and thrust of an electric fan powered aircraft?

I'm confused about the relation between IAS, TAS, thrust, and shaft power, for an electric application. Yes, higher air is thinner, and thrust goes down due to higher airspeed. What I've researched ...
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1answer
177 views

How can I calculate the minimum thrust to weight ratio required for a given takeoff distance?

I am building a plane and I have a take-off distance of 50ft, is there a way for me to estimate the thrust-to-weight ratio required for this constraint (even if it was in terms of say wing loading)?
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2answers
145 views

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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1answer
111 views

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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2answers
557 views

How much thrust is produced on an A320 at takeoff and during cruise?

Where can you get the drag polar of the A320 at cruise and TakeOff?
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2answers
138 views

Can briefly explain the principle behind the inversion on this power required curve?

I’ve noticed on several graphs in the “Advanced Pilot’s Flight Manual”, that power available is lower for any given speed at 10,000 feet as compared to sea level flight. The power required curves ...
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2answers
1k views

Flex temperature isn't actually "fooling" the FADEC, right?

I'll be using Airbus terminology here because that's what I know, but I guess the concepts are universally applicable. The way I understand flex temperature is: It's a user interface for pilots to ...
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2answers
325 views

Is it true that high-bypass engines are inherently inefficient at higher speeds?

Power consumption=Kinetic energy=$1/2mv^2$. Thrust=momentum change=$mv$. I keep being told that aircraft engines are most efficient when their exhaust velocity closely matches the freestream. The ...
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3answers
235 views

Can tailwind produce reverse-thrust?

I know that the answer will probably be no, and this question might sound silly, but I wanted to think outside of the box. If engine air intake comes from the front, and is pushed out through the ...
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2answers
150 views

Is this plasma-thruster experiment actually measuring thrust? [closed]

This experiment, which is being presented as an initial exploration of the feasibility of using microwave-generated plasmas in a sort of electic jet engine, has been attracting some attention in the ...
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1answer
318 views

What is takeoff power? [duplicate]

I Am asking about the takeoff power here not how the aircraft takes off. What do I need if I want to calculate the power required by an aircraft to take off? What parameters should I consider?