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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How large are the banners that are trailed behind small planes for advertising?

How large are the banners that are used for aerial advertising, and how much do they normally weigh? Example: source: © Raimond Spekking / CC BY-SA 4.0 (via Wikimedia Commons) Wikipedia page on ...
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30 votes
8 answers
5k views

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 ...
Stelios Adamantidis's user avatar
29 votes
5 answers
28k views

Why are "counterweights" used in aircraft production?

From this question, manufacturers use "counterweight" or "ballast" when producing aircraft. Why is the use of weight necessary? Supposedly aircraft should be made as light as possible, and ...
kevin's user avatar
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27 votes
3 answers
29k views

Why are airlines so concerned with checked baggage weight?

Why is it that commercial airlines are so concerned with checked baggage weight, such that they charge extra just for the privilege of checking in a suitcase with a limited weight (e.g. 15kg), and ...
komodosp's user avatar
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26 votes
5 answers
11k views

Why do all airliners have life jackets?

According to this question, life jackets are not mandatory in planes that do not fly over large bodies of water. However, I have never been on an airline flight without life jackets (and the ...
Steven Mathey's user avatar
26 votes
4 answers
18k views

What is the reasoning behind using depleted uranium as counterweights in the 747?

I recently found out that some of the earlier models of 747 had between 600 and 1100lbs of depleted uranium as counterweights. These counterweights were found in 747s manufactured between 1968 and ...
Ron Beyer's user avatar
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15 votes
3 answers
12k views

What are the concerns and consequences of an overweight landing?

If a 777 ER has to immediately land after takeoff on a planned 14,594 km trip (in the case of a fire, e.g.), the landing will be executed with a very heavy aircraft. What are the major concerns of ...
Jonas G. Drange's user avatar
11 votes
3 answers
3k views

What are the physical laws for upscaling an RC model to 1:1?

What are the laws of physics for upscaling an RC model from a smaller to larger scale or even to a full sized 1:1 aircraft? I guess the basic thing may be lift/weight ratio which was nicely described ...
Kozuch's user avatar
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11 votes
1 answer
7k views

How heavy are the Boeing 747 landing gear?

Does anyone know how heavy are the combined landing gear on a Boeing 747? It would be interesting if someone has also weight statistics per gear (nose gear and the four other main gear).
Ingþór Ingólfsson's user avatar
11 votes
1 answer
774 views

What is the significance of the 10,600 lbs MTOW limit?

I recently noticed that several airplanes have MTOWs very near or exactly 10,600 lbs. That was an interesting phenomenon to me because I am familiar with the 12,500 lbs MTOW regulatory limit on ...
Charles847's user avatar
10 votes
5 answers
3k views

How has weight been reduced in commercial aircraft design and how will this trend continue?

Reducing weight of aircraft has become a priority as the aviation industry seeks greater fuel efficiency and commits to strict emissions targets. How much weight has been cut from single and twin ...
avhack's user avatar
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9 votes
3 answers
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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.
user37419's user avatar
9 votes
3 answers
6k views

How much water does a passenger airliner carry?

How is the amount of water for (a) toilet and (b) drinking to be carried by a flight calculated in the industry? Is there any formula or thumb rule using which we can roughly estimate the amount of ...
Wright Brother's user avatar
9 votes
2 answers
758 views

What is the largest aircraft (by max takeoff weight) in which all engines are in the tail?

The largest one I'm aware of is the Il-62, with a whopping 4 turbofans at its tail. Max takeoff weight is 165 tons. I actually don't care how many engines there are, as long as all are at the tail. I ...
DrZ214's user avatar
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9 votes
1 answer
962 views

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?
Someone's user avatar
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8 votes
6 answers
5k views

How does aircraft weight affect landing distance?

I am a private pilot. I posed a question to instructors in the flight school and got differing answers. For a given aircraft, landing at the same speed, with everything the same except for landing ...
Tom Tompkins's user avatar
8 votes
2 answers
5k views

Which part of aircraft is contributing the most weight of airplane?

Which part of the aircraft contributes the highest portion of weight? Note: we had argument that, wires connecting the avionics systems are the major contributors of aircraft weight. Due to some ...
Lucky's user avatar
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8 votes
2 answers
635 views

Would a lighter aircraft require the same amount of power than a heavier one to fly at the same speed?

I had a question come up: If aircraft A is identical to aircraft B, except that aircraft B weighs 200 kg more. Which of the following statements are true? The answer I selected was wrong: ...
Jesse's user avatar
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7 votes
2 answers
2k views

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 ...
Wasserwaage's user avatar
  • 1,640
7 votes
4 answers
1k views

Is an aircraft's maximum landing weight really weight, or is it mass?

I'm calculating the lift of a Cessna 172 and I don't understand the numbers given for weight. The maximum landing weight is 2550 pounds which is nearly 1134kg. But does that mean 1134 Newtons (weight) ...
wonwoo's user avatar
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6 votes
4 answers
4k views

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 ...
Nick's user avatar
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6 votes
2 answers
1k views

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 ...
nerdfever.com's user avatar
6 votes
1 answer
3k views

What is the average weight difference between composite and metal airliners?

Is there any rule of thumb for weight savings using composite materials. For example, is there an early model large airliner like the B747 or even B737 that later was modified with composite wings or ...
jwzumwalt's user avatar
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6 votes
5 answers
3k views

What happens during a powered descent?

I was having a discussion with my friend about equilibrium condition in flight: Scenario: While going in straight and level flight, say I reduced my airspeed by 30 mph. At the same time keeping the ...
user2927392's user avatar
  • 2,359
6 votes
1 answer
244 views

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 ...
Ted Staggs's user avatar
6 votes
1 answer
333 views

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 ...
DrZ214's user avatar
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5 votes
5 answers
3k views

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 ...
Ginger's user avatar
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5 votes
1 answer
4k views

Why aren't there V-tail airliners?

Since a V-tail is lighter and generates less drag than a conventional empennage, why has this solution been put away from production?
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5 votes
1 answer
593 views

If airliners profit by moving luggage from checked to carry-on, why do some LCC gate-check luggage?

According to this answer, the less luggage is transported as checked luggage, the more "room" (in terms of weight) there is to bring along cargo, and thus more profit. At the same time, some LCCs ...
JAD's user avatar
  • 153
5 votes
2 answers
4k views

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 ...
clentinbon's user avatar
5 votes
0 answers
180 views

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 ...
Zaz's user avatar
  • 1,559
4 votes
2 answers
1k views

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 ...
Abdullah is not an Amalekite's user avatar
4 votes
2 answers
825 views

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?
Emerson's user avatar
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4 votes
1 answer
355 views

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 ...
stevederekson555's user avatar
4 votes
1 answer
367 views

Why is the thrust/drag increase much lower at a lower FL with weight the only variable?

From and related to: What is the relation between drag and weight? Friction drag is not affected by the angle of attack change. The [induced] drag will increase with the square of the mass ...
user avatar
4 votes
1 answer
772 views

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. ...
user66219's user avatar
4 votes
2 answers
4k views

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 ...
Saurabh Kumar's user avatar
4 votes
2 answers
406 views

Does Raymer's installed engine equation include the weight of the pylon?

I am currently modelling an aero engine and require the weight breakdown of the individual components, I have the dry weight of the engine and need to verify the pylon and nacelle weight. Raymer has ...
martin 's user avatar
4 votes
1 answer
233 views

How do I calculate new minimal speed for a glider when I put water into the tank?

Lets say a glider weights 400kg and has a minimal speed of 70km/h. When it has additionally 100l water, so in total 500kg, what is the new minimal speed? I would argue, that in order to reach the ...
MichaelW's user avatar
  • 241
3 votes
2 answers
543 views

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 ...
Abdullah is not an Amalekite's user avatar
3 votes
2 answers
436 views

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 ...
user40245's user avatar
3 votes
2 answers
3k views

What is the weight limit for a pilot to eject from an F-100?

What is the maximum weight for a pilot to use the ejection seat in an F-100 fighter?
Pilot's user avatar
  • 31
3 votes
1 answer
172 views

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, ...
Sasquatch's user avatar
3 votes
2 answers
211 views

Is there any way to estimate the weight difference between a trimmable horizontal stabilizer and a fixed tailplane?

I am trying to estimate the benefits of using a trimmable horizontal stabilizer (THS) instead of a fixed tailplane. In my model I use a T-tail (Sh~30 m), and I can trim the aicraft in every condition ...
JGG's user avatar
  • 341
3 votes
1 answer
53 views

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 ...
Nahuel Prieto's user avatar
3 votes
1 answer
14k views

What is the maximum body weight allowed for a pilot?

What is the maximum allowed body weight for a new commercial pilot student? Would someone weighing 130kg be rejected on the basis of health? If so, what should that person weigh to avoid the ...
The Better Aviator's user avatar
3 votes
2 answers
3k views

Is V(L/D)max equivalent to best glide speed regardless of weight, engine, height, etc.?

I've read Carson's paper on V(L/D)max, and while theoretically interesting, it does not seem to me to be useful in actually finding the V(L/D)max of an arbitrary aircraft, as it assumes knowledge of ...
Max von Hippel's user avatar
3 votes
0 answers
326 views

How much does basecoat/clearcoat paint cost for an airline?

Suppose an airline with 15-20 A320 wanted to change the paint for the entire fleet, how much would it cost approximately? I need this for my thesis, but unfortunately, paint manufacturers I contacted ...
Sverg's user avatar
  • 103
2 votes
2 answers
1k views

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 ...
Air Canada 001's user avatar
2 votes
3 answers
511 views

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 ...
L29Ah's user avatar
  • 137