# Tag Info

### From a safety standpoint, which is better: voice aural alerts or tone aural alerts?

This is only my personal experience from my initial-course CRJ simulator training, but I found that voice alerts tended to be more effective at distracting you or pulling you out of mental fog. For ...
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### From a safety standpoint, which is better: voice aural alerts or tone aural alerts?

Older aircraft designed before the B787 typically had the variability in design that you refer to. When the B787 started development, the FAA issued special conditions that required Boeing to address ...
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### What is "negative geometric washout"?

I strongly suspect that what you read was an example of poor writing or word choice, or a mis-translation. Almost certainly what was intended, was to say that the wing should have anhedral-- i.e. ...
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### Why does the 767’s main landing gear appear spaced considerably farther apart than airplanes of a comparable size?

The reason why the main landing gear appears to be "narrower" in the second and third photo is Perspective Distortion: when the photographer is standing very close to the airplane, the parts ...
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### Are there cases where a double horizontal stabilizer is useful?

A double horizontal stabilizer has been useful during early days of aviation, for structural reasons regarding heavy bombers. Airplanes like Vickers Vimy or Handley Page Type O, had a biplane ...
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### Will ice on an airfoil work as a vortex generator?

The first question is less "will it?" and more "can it?" delay stall, where the answer to the latter question is yes! There is research abound studying roughness effects like this. ...
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### What are the loads in a horizontal stabilizer?

The way I'd approach this problem may vary depending on what information is available about the aircraft and flight condition you are analyzing, but here is a rough outline of how I'd suggest ...
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### Are there any aircraft with powered landing gear?

An Electric Green Taxiing System (EGTS) is an electric taxiing system which allows aircraft to taxi and pushback without requiring the use of aircraft engines, and is designed to reduce fuel volumes ...

### What are the loads in a horizontal stabilizer?

If you are into commercial transport aircraft, you might start with: "Structural Loads Analysis for Commercial Transport Aircraft" by Ted L. Lomax, ISBN (print): 978-1-56347-114-8, Chapter 8:...
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### Are there cases where a double horizontal stabilizer is useful?

Double horizontal stabiliser have been recently introduced also in the helicopter world with the H160 but for a slightly different reason. Horizontal stabiliser on the H160. Source https://en.m....
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Accepted

### How can I calculate the TOTAL drag of the ENTIRE airplane?

EDIT Doing the math at a speed of 149kts (as suggested by @RobertDiGiovanni) and a weight halfway between EW and MTOW, gives a total drag of some 308lbs which should be a reasonable value. Try with: ...
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### How can I calculate the TOTAL drag of the ENTIRE airplane?

Drag of the $entire$ airplane is readily available by gliding, or monitoring fuel consumption. Checking fuel consumption is a bit more complicated because what you really need is thrust. in steady ...
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### What do the tail numbers on aircraft mean?

Naming tails after exceptional air warriors is an old Indian Air Force tradition. E.g. the Indian Air Force named the first Rafale trainer aircraft RB 008, in a tribute to Air Marshal Rakesh Bhaduria, ...

### Why do planes use wire HF antennas instead of smaller ones used by airliners?

The antenna length is purely a function of frequency. In other words it is a function of the radio systems that were prevalent when the aircraft entered service, and not specifically the age of the ...
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### Do F-22 Raptors have different chemical colored coatings on the canopy?

No, all canopies manufactured for the F-22A aircraft are done in an identical fashion. It’s just lighting reflecting off the canopy at different angles, different backgrounds behind them, etc.
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### How is lift transferred from rotor to chassis (or weight, the other way around)?

EDIT: it is the main gearbox of an H145 aka EC145 aka BK117 I might have found the right picture: This cutaway displays the main gearbox of a H145 and nicely depicts all the bearings (in light blue)...
• 916
Accepted

### Why does the 767’s main landing gear appear spaced considerably farther apart than airplanes of a comparable size?

The Boeing 767 main landing gear is not actually spaced further apart than other twin-engine wide-bodies: Aircraft Wingspan Gear Spacing Fuselage Width Gear Spacing:Fuselage Width B767 48 - 52 m 9.3 ...
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### How do airplanes with thrust lines above CG still fly without a down pitch moment?

How do airplanes with thrust lines above CG still fly without a down pitch moment? For straight horizontal flight, the total pitching moment needs to be zero. With a thrust line above CoG, the thrust ...
• 58.9k
1 vote

### How do airplanes with thrust lines above CG still fly without a down pitch moment?

Here a solution for a related topic, what if thrust line is below the CG (Sukhoi Su-27): By tilting the nozzle down to point the thrust vector to CG: At some stage of the design evolution, the engine ...
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### How do airplanes with thrust lines above CG still fly without a down pitch moment?

What you generally do with a high thrust line is place the horizontal stabilizer surface directly in the propeller wash to help offset some of the trim change caused by thrust changes. When you add ...
• 110k
Accepted

### Fixed-Wing Stall Speed Equation Valid for Differing Planetary Conditions?

You are correct. The maximum coefficient of lift (CL_max) is non-dimensional, so it will be the same regardless of gravity, density, speed, mass etc. (it is not perfectly non-dimensionalized, as flow ...
1 vote

### Fixed-Wing Stall Speed Equation Valid for Differing Planetary Conditions?

Yes, basically you just calculate a new stall speed for an airplane where mass, air density and gravity change, but wing area and maximum coefficient of lift remain constant. It is valid if similar ...
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### Can a Supersonic aerofoil have Max thickness near the middle?

Yes, the lowest wave drag for a given thickness can be achieved by placing the maximum thickness in the middle. Any body moving through a fluid must push this fluid aside. When this movement happens ...
• 220k

### Do gyroscopic forces (from rotating engines) significantly affect yaw or pitch?

Yes, gas turbines can have noticeable gyroscopic effects at low airspeeds. The Harriers RR Pegasus has contra-rotating spools for that reason.

### Fixed-Wing Stall Speed Equation Valid for Differing Planetary Conditions?

Stall speeds vary widely based on many different factors, some of which you have listed already. However, an airfoil will always stall when it exceeds the critical angle of attack -- the point at ...
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### Matching the Drag Equation to Real Airplane Data

What you describe is commonly called the quadratic drag equation. While not perfect, does this methodology make sense? Yes, see answers here, here and here, for example. But you can easily refine ...
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### How is CFD used in aircraft design? Qualitative vs Quantitative?

The quick answer is it depends. As for the small businesses doing aircraft design generally sweeps or trades will be run on a low to mid fidelity multidisciplinary design code to map the design space. ...
Accepted

### How is CFD used in aircraft design? Qualitative vs Quantitative?

It really depends on what your objectives are. For design optimization, the currently available automated optimization methods (Adjoint and other topology methods) are not as good as a well ...

### Will ice on an airfoil work as a vortex generator?

No. A vortex generator protrudes up into the free stream, and the horizontal tornado it creates circulates partly in the free stream and partly in the turbulent boundary layer. Spiralling free stream ...
• 110k
1 vote

### Why increase chord length for supersonic aircraft (swept vs delta wings)?

Open to all answers, but mathematically justified would be awesome. Aerodynamics is what keeps aeroplanes in the air, and is ruled by physics. The equations used in OP are simplified physics ...
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