Questions tagged [aircraft-design]

Questions about the different choices that aircraft designers (typically aerospace engineers) make in order to create an aircraft.

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2
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2answers
83 views

Why does this plane have vapor trails coming out of wings?

See this video of Birmingham strong crosswinds landings: At 2.57, there is a 737-800 landing (screen shot below). One can clearly see some vapor (?) coming out of ...
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1answer
79 views

How can I identify the aircraft’s phase of flight in this picture?

It’s me again, can anyone explain how to know the aircraft’s phase from this picture? Is it cruising or descending if so why its flaps up?
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26 views

Is there any bibliography for triplane aircraft design?

I've been tasked with designing an RC aircraft that has the greatest lift force for a specified wingspan, total length and takeoff velocity, and thus have been studying the different wing ...
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1answer
241 views

Why is 51,000 ft a common service ceiling for business jets?

According to this article on aerospace-technology.com, many of the larger business jets seem to have a service ceiling of 51,000 feet. Other sources verify this trend. What is the reason for this, if ...
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0answers
44 views

Could an airliner be more efficiant lower and slower? [duplicate]

Could an airliner be efficient using ground effect as opposed to there normal cruising altitude even if they have to go slower and be shaped differently?
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1answer
478 views

What is this type of aircraft?

In this picture, could anyone describe what type of aircraft and which airline it is?
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18 views

Where can I find wind tunnel pressure data for various airfoils?

I'm working on a simple panel method solver based on thin airfoil theory and I would like to validate my code using wind tunnel data. Is there any place where I can find pressure distribution data ...
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2answers
106 views

XFY-1 Vertical take-off mechanics

Hi I saw this video the other day of an XFY-1 doing a vertical take-off and landing and moving left to right while hovering. See the video Here. After watching this I had a few questions on how ...
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2answers
2k views

What are the most powerful airplanes that ever flew?

This question What are the least powerful airplanes that ever flew? made me wonder what the most powerful manned airplanes are that ever flew. There are two sensible categories, I suppose: Most ...
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1answer
151 views

Why does the KC-46 use two sensors for MCAS when the 737 Max doesn’t?

this article states The KC-46 has a two-sensor MCAS system, which “compares the two readings,” the Air Force said. I’m aware that the 737 uses two sensors and always has, but the computer reads ...
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0answers
26 views

What is the effect of wing flex on wing's airfoil shape and its performance effect on wing?

There are good amount of discussion on wing flex in this forum. I am more interested in understanding the effect of flex on aerofoil shape of the wing and its impact on flight performance. Do ...
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4answers
4k views

Why are no recent small aircraft designed to be “characteristically incapable of spinning” as the Ercoupe was?

I'm a student pilot at a flight school that primarily flies RV-12s as a trainer. We had one day that through a booking error meant that all the RV-12s were booked so we had to use their Ercoupe 415-C ...
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6answers
5k views

What are the least powerful airplanes that ever flew?

What manned airplanes have achieved flight with the least powerful engines (no gliders!), and what was their top speed? Im sure I've heard of an airplane with an 8hp engine capable of exceeding 120 ...
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3answers
3k views

Why do modern aircraft tend to have angular tails?

In the WWII-era and earlier, many (most?) planes had rounded tails, even high-speed and high-performance fighters such as the Bf 109 K, Ta 152 (though it is more square-ish), P-38, Hawker Typhoon, and ...
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2answers
184 views

What is the function of the Apache's Strap Pack?

I have recently been reading about the issues with the Apache's (AH-64) strap packs. I've read that the strap pack holds the rotor blades on to the hub. However, it appears the blade also connects ...
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0answers
56 views

Is there a difference between blended wing body and hybrid wing body?

Internet searches for "blended wing body" and "hybrid wing body" bring up very similar designs. Is there really a technical difference and if so who lays the convention down?
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0answers
56 views

What's the benefit of cranked wing for commercial airplanes [duplicate]

Many commercial airplanes have a kink in the wing geometry. A discontinuous change in the wing trailing edge sweep is present in the wing of the A320. What's the benefit of this? Is there any ...
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1answer
94 views

Does the center of mass for an airplane have to be over the wings?

I am designing a model aircraft that will have 4 propellers in a square configuration (think like a quadcopter) so that it can take off and move around like a quadcopter, then transition into plane ...
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8answers
9k views

Double deck vs wide body airliner, why would anyone build a double deck one?

I don't understand why double deck aircraft (or multiple decks in general) are a good idea. They must be, because there is a significant amount of them. But given a cross area, which should roughly ...
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0answers
18 views

Should tailplanes have symmetric aerofoils? [duplicate]

Do tailplanes generally have symmetric aerofoils, or do they posses inverted aerofoils to counter the pitch up moment? Is there an advantage to the use of the symmetric aerofoil in an all moving tail? ...
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1answer
123 views

Airfoil and Wing Analysis for Transonic Speed (M = 0.85 and Re = 42 million)

I am working on a project where I have to design a plane which has to cruise at 0.85 Mach at 35,000 ft. While working on the wing design, I quickly discovered that 6 series airfoils, with a good ...
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2answers
73 views

How to select and electric propulsion system for my experimental Ultralight?

I've been trying to design and build, my experimental Ultralight using electric propulsion system, My plane designed base on Slaler and Gensis ultralight , following is the primary calculation Empty ...
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0answers
124 views

Ailerons deflection of the F16 in take off and landing gain?

Let's say you are at a safe altitude and landing gear is down and the aircraft is in To/L gains and you want to do aileron roll and apply full left (or right ) stick to do the rolling maneuver.The ...
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1answer
244 views

Why is TO/GA button disabled in 777 with weight on wheels or below 2 ft RA?

Recently a final report for accident of an Emirates B777-300 at Dubai on 3rd August 2016 was published. An important factor there was that when the pilot tried to recover from long landing by going ...
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4answers
1k views

Does the tailplane have a positive/negative camber?

I've read that the tailplane produces negative lift, so does that mean it would function like an inverted wing (has negative camber)? The image below is the best illustration I could come up with. ...
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1answer
131 views

How does maneuvering affect radar detection of stealth aircraft?

Stealth aircraft like the F-22 and F-35 have very low radar cross sections. These planes have angles of their fuselage set-up in a way to deflect radar signals. As far as I understand another stealth ...
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0answers
111 views

What happens when an airplane is retired?

With launch of new models every few years, what happens to the older airplanes which was in service for more than decades? Where does it get stored. Who buys old airplanes? Does manufacturers buys ...
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0answers
77 views

Can friction joints be certified?

I remember being told that friction cannot be considered when designing joints as the friction coefficient can change. This could happen for instance due to water being trapped inbetween components. ...
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1answer
138 views

Did older Airliners use a pitot-static system?

Aircraft like the B707, how would the aircraft gather speed and altitude data? And if they used pitot static system by that time, was there ever anything else that gathered the speed data?
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5answers
10k views

Why Didn't the USSR Build An X-15?

In the history of aerospace engineering in the United States, the X-15 is lauded as a critical and necessary step on the path to manned spaceflight. Throttle-able chemical rocket propulsion systems, ...
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2answers
536 views

The F 18 Hornet and Mig29 ailerons from the external parts of the wings go up some degrees in flight .Why?

In some parts of the flying envelope of the F 18 Hornet and Mig29 the ailerons from the external parts of the wings go up in sync . They're made to go one up one down in order to get rolls,not ...
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1answer
105 views

What are the advantages of dual counter-rotating rotors vs coaxial rotors?

It just seems to me, as though, dual counter-rotating rotors are a much better solution (Chinook) than coaxial and that the center of gravity is offset to allow useful loads to be spread out. Even ...
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1answer
184 views

If the modern airliner was redesigned from scratch, would it look functionally different? [duplicate]

If the modern airliner (Boeing/Airbus) was redesigned from scratch today without any need for "backward compatibility", would it look functionally different from the current design? And if so, what ...
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1answer
154 views

What is the feasibility of fitting all aircraft with black boxes? [duplicate]

In the wake of the tragic helicopter crash on January 26,2020 which killed Kobe Bryant and eight other people, it would seem to make sense to follow transport category aircraft standards and fit all ...
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3answers
214 views

How do a helicopter's cyclic and collective transfer commands to the swash plate?

I understand the function of the cyclic and collective, and I am specifically wondering if anyone has a good image/video showing the mechanism of how the flight control "mixer" works! I can't seem to ...
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0answers
101 views

How do jetliners age (major or notable checks and part replacements)?

As commercial airliners can be (and are) operated for many years (or even decades), I've started to ponder - how do they actually age? Or - in other words - what are major or notable maintenance-...
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3answers
567 views

Why don't smaller powered airplanes have better lift-to-drag ratios?

Many airliners have LDRs near 20, and it sounds like the electric Eviation Alice may have an LDR of 24 at 240 kts, but many small planes typically have LDRs of only 8-10. It seems like they could ...
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1answer
150 views

Could in flight folding wing tips lead to a safer airliner design?

As a spin-off to the recent success of the Boeing 777x maiden flight, the effects of folding the wing tips in flight were considered. Folding them down in cruise, like the XB-70 should increase yaw ...
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0answers
111 views

Why not add more blades to a helicopter? [duplicate]

There's something that bothers me inherently, and just like the Hueys from Vietnam, 'only' having two blades. Doesn't seem enough, I mean, if despite your best planning, engineering -- whatever -- ...
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2answers
111 views

What's the difference between Stress and Strain? [closed]

There's a book for Engineers, entitled: 'Roark's Formulas for Stress and Strain', some describe it as 'High level Mathematics'. So what?
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1answer
148 views

What is the physical-based/theoretical reason why supersonic area ruling works?

Supersonic area ruling is used to reduce the drag rise that occurs as aircraft pass through the transonic regime. While it has been validated experimentally, what is the theoretical/physics-based ...
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2answers
131 views

How to correct CG on a not leveled aircraft?

I am tasked with weighing a fixed wing aircraft. the aircraft can not be leveled because the leveling points are damaged. therefor it is going to be weighed not leveled, an inclinometer will read a ...
3
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2answers
367 views

If Boeing used two sensors instead of one simultaneously, wouldn’t they be in the same position today?

this article states that the original version of MCAS was suppose to rely on two sensors, One sensor will detect a high angle of attack, therefore activating MCAS The other sensor will ...
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1answer
110 views

Is there a rule of thumb for aircraft design? [duplicate]

I'm wondering how to best scratch build an rc aircraft and what rough proportions the aircraft should be in. I'm aware of the fineness ratio that determines the width to length ratio of a cross ...
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1answer
147 views

Are electromechanical actuators used in aircraft other than the Boeing 787?

Are there any large (non-experimental) civil or military aircraft that use electromechanical actuators (EMA), other than the Boeing 787?
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1answer
162 views

Would a 2nd row of distributed props on a 2nd staggered wing of a biplane increase its efficiency?

Would a 2nd row of distributed props on the rearward wing of a biplane with 25% gap and 150% negative stagger increase the efficiency of a biplane ULTRALIGHT, 25MPH, Re 500K? ( rear wing is 25% lower ...
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2answers
121 views

Why do airfoils in an airplane's wings have different shape and size along its span?

Why wings of an airplane consist of different shape and size of airfoil. What will happen if the thickness of wing are same throughout the wing?
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3answers
8k views

Why is the most common hydraulic fluid so poisonous?

The usual hydraulic fluid, Skydrol, is poisonous. If it makes it to the air conditioning system, it causes fume events that may have adverse health effects up to and including at least one fatality. ...
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3answers
241 views

How to adjust the center of gravity of an aircraft if not level when being weighed?

how do you adjust the center of gravity when weighing an aircraft in not-leveled position using platform scales under the nose and the main gears, and dropping a plumb bob to mark the gears locations.
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1answer
55 views

What is the relationship between aspect ratio and divergence speed?

Why do longer wings with higher aspect ratios have lower divergence speeds?

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