# Questions tagged [weight]

In science and engineering, the weight of an object is usually taken to be the force on the object due to gravity. Weight is a vector whose magnitude (a scalar quantity), often denoted by an italic letter W, is the product of the mass m of the object and the magnitude of the local gravitational acceleration g; thus: W = mg. The unit of measurement for weight is that of force, which in the International System of Units (SI) is the newton.

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### What can happen if everyone congregates at the back of a parked plane? [duplicate]

On a recent flight on an A320, after landing, when parked up at the gate, the cabin crew announced something along the lines of "Stairs will be at the front, please do not congregate at the back ...
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### How do the various Weight on Wheels (WoW) systems work?

I know that Weight on wheels (WoW) switches indicate whether the weight of an aircraft is resting on its wheels. WoW information reveals whether the aircraft is airborne or on the ground. It also ...
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### TEB-NAS Midsize Jet max weight

We have hours with Sentient Jet and typically fly their Midsize jets -- Hawker 800, Citation XLS, Lear 60 etc. Usually only the XLS will work for us due to large luggage. Can someone help with me with ...
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### What is the difference between gross weight and MTOW in an aircraft specification?

On Wikipedia you often find aircraft specified with a separate "gross weight" and "MTOW". The term "gross weight" implies "weight with maximum fuel and payload"....
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### What is unarmed weight?

I'm doing research about fighter planes, and I've noticed two terms: unarmed weight and empty weight. I've tried to find what the difference between these two terms is, but I can't find a definition ...
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### How much of the empty mass of a typical airliner consists of rivets?

How much of the dry mass of a typical airliner (let's say a Boeing 737 or Airbus A320, if a particular model is needed) consists of rivets used in assembling the plane?
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### Why does aircraft weight influence position (installation) error in pitot-static systems?

I am a private pilot from Argentina studying to become a commercial pilot. In one of the books I was given to study, published by the Chilean air force, the there's a claim (in Spanish, page 36) that ...
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### Is there a reason why the vertical lines of some airplane envelope graphs are not parallel?

I am working on a project to develop an easy solution for mass and balance generation for my aviation club. (First example below) I checked the Graph of a PA-44-180 from the POH and wondered why piper ...
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### PoH says airplane climbs steeper at higher weight. Why? How?

Here's a puzzle. Looking at the PoH of my aircraft, it appears that the climb angle (distance to clear a 50 foot obstacle, starting from the end of the ground roll) is shallower at lower weight than ...
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### What happens if the current ICAO method disagrees with double wheel/dual tandem etc?

Is the old U.S. method (a weight max for each landing gear kind) simply ignored? Planes with 3, 12, 14 and 22 wheels are common after all but gear types with those numbers often aren't listed. If the ...
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### Why has structural efficiency (OEW / MTOW) not improved despite increasing use of carbon fiber?

Where can I find information on the weight breakdown of civil aircraft? I am interested primarily in trying to understand why structural efficiency (OEW/MTOW) has not improved despite increasing use ...
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### Why are emergency parachutes for pilots so heavy?

Parachute technology doesn't seem to have got much lighter in the past few decades. It seems that most emergency parachutes designed for pilots still weigh about 15 lb. And yet a Cirrus BRS designed ...
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### Landing gear drag and weight calculations

I have read numerous books and researches, but I couldn’t find any formulae that actually work for how to calculate the following (for commercial aircrafts): 1- Drag coefficient for a retractable ...
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### Can weight reduce a plane's glide ratio?

The FAA says glide ratio doesn't change, regardless of weight, here on page 5-7. Glide ratio is not affected by weight because, while a heavier glider sinks faster, it does so at a greater airspeed. ...
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### What should be the size of a lifting body aircraft that can carry 5 passengers (385kg/850lbs)?

So I just want to know the size of an aircraft with a lifting body that would fly at low altitudes (around 40 meters/100 feet), and at low speeds (maximum 200 km/h 124 mph). But I don't know if these ...
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### Will a heavier aircraft be more efficient at high speeds(cruise)? [closed]

Since heavier aircraft have more mass and inertia, they will have less drag because it will be easier for them to push through the air so does that mean that we can achieve the same cruise speed with ...
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### If an aircraft diverts to another airport for mechanical reasons, does the dispatcher create a new flight plan?

Let's say the aircraft is flying from LEJ (Leipzig/Halle Airport, Germany) to DXB (Dubai International). And enroute if the aircraft needs to divert over Turkey to land because of one engine failure, ...
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### Why is maximum zero fuel mass used in take off mass calculation?

In calculation we consider maximum takeoff weight , maximum landing weight and maximum zero fuel weight we selected the lowest of below mentioned Maximum Zero fuel weight + Take off fuel Regulated ...
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### How much heavier will a fuselage be with a 10% increase in diameter?

Is there some kind of a ratio or a very general rule of thumb that describes fuselage weight increase in relation to the increase of its diameter? (All other things being equal, length etc.) Note: I ...
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### Is it possible for the lift force unit vector to be equal to the weight force unit vector?

I know that the drag force is parallel to the direction of flow, thus equal to the unit vector of velocity. But if you consider a vehicle, when its angle of attack is below the velocity vector from a ...
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### On what basis is the weight unit of the FQIS selected by airlines of various countries?

On what basis is the weight unit of the FQIS (Fuel Quantity Indicating System) selected by airlines of various countries? Does it depend on the local country for using imperial or metric units?
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### What is the lightest powered hang glider?

And how light can it be for foot-launch and climbing on its own power? I know there are stunningly light paragliders, but they are slow, inefficient, the wings wear out quickly, and they are prone to ...
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### What are engineers trying to maximize when they design for takeoff at MTOW? (It seems to me the only free variable is the OEW.)

For a commercial flight, the payload it carries is the weight of passengers and their baggage. Therefore fixed by seat configuration. Fuel weight is determined by the range of the flight. MTOW or ...
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### Is it possible for an airplane to enter another airplane? [duplicate]

I was making some cool fictional airplane designs and realized that most of my larger airplanes have a bay inside that stores a plane or two. But then I thought, is it even possible to make a plane ...
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### What made Concorde so heavy?

The Concorde burnt five times more fuel per passenger mile than the 747. A huge contributor must have been the immense empty weight per seat, three times that of the B747. B747-300 Concorde Empty ...
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### How heavy are the folding wingtips of 777x?

To understand the mass penalty that is induced by a folding wingtips, as a first order approximation we can start with just the wingtip's mass without the actuating mechanism. I could not find the ...
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### 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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### Does the center of lift have to be in line with the center of mass?

Imagine 2 theoretical planes, A and B, shown in the image below. The center of mass is yellow, and the center of lift is blue. Would plane A and plane B work as well as an airplane with the center of ...
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### What do we mean by taking the lowest of ZFW; TOW and LW to determine the maximum takeoff weight of the day?

Firstly, I understand that the maximum permissible takeoff weight can be limited by landing weight because landing weight plus trip fuel gives us one take off weight. We obviously do not want to be ...
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### How much aluminum was used in the Boeing 727?

What is the weight of aluminum used in the Boeing 727 fuselage? Do you know where I can find it? Any manual or site or something like that?
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### How fixed air, gas and fixed weights in rigid airships is computed in this book?

I hope I am posting this in the right forum. My current problem is part aviation, part maths. I have been struggling with the following computation ( Burgess, Charles Paine. Airship Design. Honolulu, ...
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### Are General Aviation tires filled with Nitrogen?

Long story short, I'm working on a concept for a book. We all know why commercial aircraft have nitrogen tires, but my question is if GA aircraft have nitrogen tires, or are they just filled with ...
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### Why does the mass penalty of cantilever vs externally braced wing decrease with aircraft size?

From Wikipedia Cantilever wings require a much heavier spar than would otherwise be needed in cable-stayed designs. However, as the size of an aircraft increases, the additional weight penalty ...
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### For electric aircraft, is MTOW = Empty weight + Maximum payload?

Electric aircrafts and most drones have simple powertrains, and their weight does not vary along the flight. After reviewing this thread I assume that: MTOW = Empty weight (batteries incl) + max ...
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### Why does increasing a glider's weight using water ballast improve its speed and performance? [duplicate]

I was studying gliders and how they fly. There is a point that's not clear to me: why does using water ballast improve the performance/speed of a glider? If I understand correctly, my glider jumps ...
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### How to calculate bending moments and shear forces on a wing?

I am trying to create a MATLAB script to plot the Bending Moment Diagram (BMD) and Shear Force Diagram (SFD) as a function of spanwise distance, x, along a wing from the wing root (x=0) to the wingtip ...
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### Are there any airliners capable of vertical climb with engine thrust only by pointing the nose up?

So, sort of inspired by this question, I was wondering if there were any passenger airliners with enough thrust to fly straight up, supported purely through the thrust of their engines rather than the ...
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### Average weight of fuel required to carry 1Kg additional cargo weight per hour [duplicate]

I'm looking for an average number here, I know there is not one correct answer as there are many parameters to take into account. Alternatively, I could also use something different, like : how many ...
1 vote
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### Do airline dispatchers pre-block seats for weight and balance on large wide body aircraft?

I was reading a Oman Air flight review and one of the bits intrigued me: I had earlier used ExpertFlyer to monitor both how busy the flight would be and the seat map. I selected a window seat ...
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### How is the impact force on the landing gear distributed in fighters?

Upon landing, what percentage of weight is distributed on the main and the nose landing gears of fighters? Upon landing of a fighter aircraft, what would be the approximate time of transfer of the ...
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### What adds more weight to a twinjet? Tail-engines or wing-engines?

Let's say we have a large commercial jet, with exactly 2 engines, capable of holding at least 200 passengers. It could be a traditional jet like the Boeing 777, where both engines are in the wing. Or ...
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### How can lift be less than thrust that is less than weight? [duplicate]

Physics in schools teaches two contradictory and mutually exclusive things: That the upward lift force on an airplane in flight equal its weight (Lift = Weight = Mass x Gravity). This is based on ...
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### Can the removal of a duty-free sales trolley result in a measurable reduction in emissions?

Recently, SAS announced that: Withdrawing tax-free sales will reduce the overall weight of the aircraft, which in turn will reduce fuel consumption and emissions. I could buy that this might be a ...
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### Trying to find the vertical acceleration by subtracting weight from lift

I'm trying to determine the vertical acceleration component of a plane with the following specifications: Density of air: 1.29kg/m3 Speed: 33 m/s Wing area: 13.97 m2 Lift Coefficient: 1.5 Mass:560 kg ...
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### Why does the DC-8-70 have the same MTOW as the DC-8-60, despite its more powerful engines?

The DC-8-70 is a more-or-less straight reengine of the DC-8-601, replacing the obsolete JT3D-3B low-bypass turbofans of the DC-8-60 with the CFM56-2C1 high-bypass turbofan. According to Wikipedia, ...
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### Would knowing the exact weight that has been loaded on a commercial plane and it's distribution be useful? [duplicate]

There's been a bit in the media about weighing passengers in order to get more accurate take off weights for commercial planes. I'm guessing the delta between a heavy set of passengers and a light ...
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### What is the weight of the fuselage (only) of the Boeing 747?

I'm wondering about the weight of the Boeing 747's fuselage.
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### How long will an aircraft need to fly before it can land without dumping fuel? [closed]

Now, I know perfectly well that the literal and unhelpful answer to the question is long enough to burn sufficient fuel that it is no longer overweight for landing. What I'd like to understand is ...
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### How does wind affect takeoff weight limits?

Two days ago I took off from BUR in relatively windy (although dry) conditions. Flightradar showed departure from runway 33, and winds were recorded roughly mid 20s kts from the N-NNE direction. ...
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