Questions tagged [weight-and-balance]

Weight-and-balance is determining that an aircraft is loaded within the limits of it's weight carrying capability and that the center of gravity is within the operational envelopes of the aircraft.

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28
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1answer
20k views

How does a commercial airliner measure its weight/mass?

Other questions currently being answered cover situations regarding planes near, at or even above their MTOW. It raises a more basic question: how is the exact "ramp weight" of an airliner measured or ...
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How do airlines handle uncertainty in passenger weight for weight and balance calculations?

When commercial airlines calculate the mass and distribution of passenger load, in the cases where they do not weigh the passengers directly, they use standard weight measures which have been approved ...
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Do some airplanes have weighing scales on the landing gear?

It seems to me that takeoff weight is an important piece of data, and if one had weighing scales between the wheels and the aircraft body, one could precisely determine it. However, searching the ...
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6answers
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Can passenger movement in an airliner make it stall?

This question shows a couple of air hostesses dancing during mid-flight and the co-pilot came out of the cabin to record it. This made me wonder: Can flight crew or passengers moving around in ...
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5answers
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Is passenger weight distribution important on a commercial flight?

This is something I've wondered about for a long time. On really large airplanes, like a 747-400 or A380 for example, I would assume that the weight of the passengers on board is a significant to the ...
25
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5answers
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Are passengers really not allowed to change seats before take-off due to weight and balance?

Just boarded an A320 with many open seats (Spirit), and the flight attendant said we may not change seats until at altitude due to weight and balance. Is he just trying to prevent pax from moving ...
11
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2answers
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How are the limits of the center of gravity chart established?

When one views a center of gravity limit chart, in this case a C-182T chart, one notices that the forward C.G. line has two small bends in it, one around 2250# mark and the other around the 2675# mark....
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8answers
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Can passenger distribution cause a parked airliner to tip?

This question on Travel.SE recounts a situation where a passenger, about to disembark from a commercial airline flight, was asked by a flight attendant to wait for other passengers to "catch up". ...
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2answers
399 views

Would an accurate weight of a loaded aircraft be helpful?

If a commercial aircraft's actual weight at takeoff is accurately known (instead of being estimated), can this help with use of thrust, optimal altitude, etc and therefore fuel savings, emissions etc.?...
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1answer
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Where is the best center of gravity?

I'm designing a plane, and I have a question. What is the best place for the center of gravity, relative to the center of lift? I've heard that it's best put just behind the center of lift, but I ...
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What alternative methods are there for controlling a plane when flight control surfaces have failed?

I saw a TV show once about Japan Airlines flight 123, in which the aft pressure bulkhead ruptured, disabling hydraulics and ripping off the vertical stabiliser. So the flight crashed after some time ...
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What are different types of weights of an aircraft?

When looking at different aircraft's specifications or in POHs/AFMs, there are several different weights of the aircraft mentioned (e.g. maximum take-off weight, maximum landing weight, operating ...
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What would happen if a plane lost half of its weight instantly?

During the Second World War the RAF had a 10,000 kg bomb, the "Grand Slam", which was dropped from a Lancaster bomber. I assume that when this was dropped the plane would lurch upwards. Is there any ...
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Does the MD-80 seat layout affect the balance of the aircraft?

The MD-80 family has a 2-3 seat layout as seen in this image: Does the layout have any influence on the balance of the aircraft and if so what is used to balance out the weight? Image from seatguru....
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3answers
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Why is managing CG (centre of gravity) important?

Why do people have to worry about CG? Is it primarily due to fuel penalty, or take-off and landing performance, or is it mostly just to keep the aircraft from tipping over during loading and unloading,...
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3answers
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Do additional passengers impact on weight and balance of a domestic airliner?

Recently my kids and I were denied access to our flight because we missed the check in window. We were informed that new calculations would have had to have been made by the pilot, despite not having ...
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2answers
917 views

Will optimising the weight distribution of a commercial flight save fuel?

Since the centre of gravity must lay in a certain location, I'm wondering if it would save fuel if it lays exactly in the right spot? Let's assume that you have an A320 and weight distribution is ...
11
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3answers
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What does %MAC mean?

A document said that the optimum CG position is from 13% MAC to 33% MAC. I'd like to know what that means, and what would this look like on an actual plane.
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Are there advantages when operating with CG near forward or aft limits?

If the center of gravity of an airplane is too far aft, it will become more unstable Iif the CG is too far forward, then drag will increase due to increased angle of attack. But what are the ...
54
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2answers
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Is it possible to install a bike rack on a Cessna 172?

I stumbled upon a nice photo manipulation on aviationhumor.net. Source My question is short and concise: Is it practically possible to do that? Is it okay in terms of aerodynamics, weight, CG? ...
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3answers
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Can a commercial airliner be too heavy to take off?

According to this question's answers, MTOW (or MTOM) is the Maximum Take Off Weight, which is everything up to and including trip fuel. Then there is one step above that, MRW, or Maximum Ramp Weight, ...
10
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1answer
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What is the weight budget of a fully loaded A380?

Wikipedia provides some numbers (typical empty weight, MTOW, max fuel capacity, etc.), but I can't seem to find more detailed figures. For a purpose of this question, let's assume a fully loaded A380 ...
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4answers
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What are the limits to lateral Centre of Gravity imbalances?

I've never seen lateral CG limits prescribed for aircraft (though I have very imited experience in this realm). Presumably, aircraft are designed to keep the center of balance as close as possible to ...
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2answers
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What is the typical weight distribution ratio between nose gear and main gear?

On an airplane with tricycle gears, the main gear supports most of the weight and is therefore the strongest. The nose gear prevents the nose tipping down, since the center of gravity is forward of ...
2
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1answer
389 views

Could passengers on an airline flight create an out-of-CG situation by moving around the airplane? [duplicate]

I've often wondered if most passenger airliners have a CG envelope which would allow the CG of the airplane to be pushed outside the limits if enough passengers relocated to the front or back of the ...
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8answers
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What if all passengers pay to check in extra baggage?

Suppose a given flight is fully booked and everybody shows up. Not only have they all brought the allowed fully loaded carry-on & checked-in luggage weight but exceed the free-limits. They are all ...
21
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3answers
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Does weight and balance of an airplane matter more on takeoff?

On a few international flights with non-full cabin, the crew has asked no one to move to open seats until the plane has finished take-off. I assumed this was just to force people to sit down during ...
17
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1answer
793 views

Why is the top left corner cut off on the cg location envelope for small airplanes?

Why does the PA-28 C.G. envelope have the top left corner cut off rather than allowing higher weights at a forward C.G. like it does at the aft C.G.? (source)
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1answer
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Is it legal to overload a plane in Alaska?

Is it true that it's legal to fly a plane over max gross weight in Alaska? If so, what are the rules?
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4answers
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How is the weight of an airplane measured?

Many very large airplanes have specific information of their empty weight. For instance the weight of an empty, regular 747-400 is 393,263 lb (178,756 kg) according to Wikipedia. The Concorde is 78,...
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1answer
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How does aircraft weight affect the glide performance? [duplicate]

Since the L/D ratio remains unaffected by the aircraft weight, will there be any effect to the gliding range?
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2answers
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How much water does the Emirates A380 carry in order to provide onboard showers?

Do you realize that we are living in a world where you can get on an airliner and disembark cleaner than when you got on? Video: Shower in A380 First Class This just blows my mind. How much water ...
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How does new media streaming technology equate to fuel cost increase?

In regards to this article on BBC, which discusses the use of streaming technology to allow passengers to watch films/TV shows etc. on their portable devices, the following statement caught my eye: ...
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1answer
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Do airlines weigh passengers and baggage before loading the aircraft?

I'm aware of some aircraft that have systems to calculate weight and balance. For those aircraft that don't have such systems, how does the pilot know they are within weight and balance limits?
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2answers
813 views

How are forward and aft CG limits calculated?

I have been tasked to create a POH for my aero engineering coursework and part of this task is to create the CG envelope for the theoretical 65 passenger aircraft. I have figured out weight, moment ...
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2answers
5k views

How often does fuel dumping from planes in flight actually occur?

There are a couple of questions about the emergency procedure of fuel dumping, used to reduce the weight of airplanes to be able to land. This is certainly interesting, regarding environmental ...
12
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3answers
4k views

Why safe take off weight exceeds the safe landing weight?

This looks contra-intuitive: if a plane can take off and fly horizontally, what prevents it from descending and touching down to the runway with the required small vertical speed?
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2answers
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How can the Antonov AN 225 only have 2 nose wheels?

I was watching the video of the AN 225 unloading at Perth airport this weekend, and it suddenly occurred to me that there are about a zillion rear wheels on the aircraft, yet only 2 nose wheels? ...
9
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3answers
635 views

Does cargo balance affect fuel efficiency in commercial aviation?

Positioning cargo such that the center of gravity of the plane is within a certain range is essential, but is there any advantage to having the center of gravity closer to some ideal point within the ...
6
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1answer
562 views

How much time does it take to calculate the leveling and weighing of big and small aircraft?

What methods are used to achieve that? According to my search : For old planes they use a plumb bob and measuring tools. On new and big planes, the process is computerized. Built-In Electronic ...
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3answers
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How reliable is the Airbus FAC calculated gross-weight?

I've noticed some variation between loadsheet weights and FAC (Flight Augmentation Computer) calculated weight. That's of course normal, since loadsheet is calculated with standard weights and FAC ...
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1answer
120 views

Flight Control Weight limitations

Does anybody know any limitations of flight control weights? For instance elevators must have same weight? What is the acceptabld difference/limits and what would be the reason of overweighting? (...
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3answers
2k views

How can I find the CG of a model aircraft based on its dimensions? [closed]

Given the dimensions and gross weight of an RC model aircraft, how can I find the center of gravity? Can I calculate it, or perhaps there's some way to approximate it?
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1answer
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How comes lift is less than weight on take-off? [duplicate]

If $$lift=weight * cos(angle)$$ this means that lift is less than weight during takeoff. Could someone please explain me why it is so