# Tag Info

30

It won't be pleasant. The main result of being exposed outside at altitude, besides the obvious hypothermia, frostbite and hypoxia, will be bruising from the 280-ish knot slipstream (it's the indicated airspeed that matters as far was what you feel, not the true airspeed), and injuries from being flung around by any turbulent flow you are in. Most of your ...

21

This is from Irish Luck - Surviving Partial Ejection from A-6 Aircraft. In this incident, the bombardier/navigator's ejection seat came part way out of an A-6, leaving the head and upper body exposed. (The web page includes pictures of the incident, as well as the pilot's account of the event.) Some quotes from the bombardier/navigator's report: Before I ...

14

User Sidestick_n_Rudder posted on PPRuNe (emphasis mine): Vs1g is the lowest speed, at which the airplane can maintain 1g, i.e. level flight. It corresponds to the Cl max Vs is the lowest speed attained during stall testing of the airplane. The pilots were able to reach this speed lower than Vs1g, but the plane was already losing altitude. The way I ...

12

A skydiver in free fall is fully supported (i.e. no longer accelerating, but falling at constant velocity) at about the same speed as your example motorcycle. Wind resistance is generally proportional to the square of speed, other factors equal (same shape in the same orientation, mainly), so moving at three times the speed on the wing of an airliner would ...

11

Referring to one manufacturer's nomenclature and systems: The "AIRSPEED LOW" caution occurs shortly after the speed drops below the Minimum maneuver speed. The Min Maneuv spd is ~30% above stalling speed for slat/flap config. Even if the auto-throttle is not engaged in any mode, as long as the auto-throttle is armed, this is the speed at which &...

9

The radio-controlled model sailplane that recently exceeded 540 mph while dynamic soaring has to be a contender. Minimum speed in this flight (immediately after launch) may have been as low as 10 mph, which probably could have been sustained by staying on the front side of the ridge. Link to You Tube video-- Though any plane ...

9

The limitation is always the lower one of the two, meaning your actual IAS must be below Vmo and your actual Mach must be below Mmo. Let us consider this case: you accelerate all the way to Vmo and climb at that fixed IAS. Two things are happening now: The TAS is increasing because the air is getting less dense. The speed of sound is decreasing because the ...

8

You don't change anything expect perhaps use short field landing technique to minimize your landing groundspeed, but otherwise you take the high ground speed. In light winds this isn't that big a deal if the runway is long enough. I regularly land with minor tailwind components, under 5 kts, when it's more convenient and there are no traffic conflicts and ...

8

The highest range of speeds will basically match up with a list of highest top speeds... take ~200 knots off of the top speed of the SR-71, and you probably have your answer. Or if the question is for currently flying jets, unless your #1 and #2 have top speeds so close that the delta in their landing speeds is greater than the delta in their max speeds, #1 ...

6

The Space Shuttle (or "Space Transportation System (STS)") reportedly re-entered the atmosphere from low Earth orbit at about 17,500 mph, and touched down as low as 214 mph, for a ratio of 81.77. https://www.nasa.gov/mission_pages/shuttle/launch/landing101.html

6

Computing GS takes into account the wind and how fast you are actually traveling through the air-TAS For example, if you are flying east bound through a mass of air (the "wind" refered to in your question) that is moving from east to west (opposite direction to your flight path) at 100 knots (pretty big headwind) and your true airspeed is 250 ...

5

"Without authorization" depends if the flight is controlled or uncontrolled. If controlled, the ATC will request the proper speed (if the exceedance is big enough to be noticeable and to matter), and if there is repeated noncompliance (i.e. to the ATC's instruction) that isn't due to an emergency (or performance limitation, e.g. heavily-loaded ...

5

Yes. The theoretical concept of "moving with the airmass" essentially says that for any given constant wind or no wind, airspeed is dependent on thrust and drag and reaches a steady state. However, in nature, especially close to the ground, obstacles such as buildings, trees and hills can make airflow anything but constant. This is why the modern ...

4

What you calculated is Equivalent Airspeed (EAS), not Indicated Airspeed (IAS) or Calibrated Airspeed (CAS). The formulas to calculate these speeds from the True Airspeed (TAS $= Ma$) are: $$\text{EAS} = \text{TAS} \sqrt{\sigma} = M a \sqrt{\sigma}$$ $$\text{CAS} \approx \text{EAS} \left( 1 + \frac{1}{8} (1 - \delta) M^2 \right)$$ (formulas from ...

4

This is a physics question, but. Speed has no relation to g-force. One g is the vertical acceleration one feels when standing still on the Earth's surface, and is equal to –9.8 meters per second per second (an acceleration, you will notice). When one changes one's velocity, i.e. accelerates, one experiences a g-force acting in the opposite direction of the ...

4

Excellent question. Yes, when you trim - you trim for angle of attack, all other factors notwithstanding (i.e., aircraft configuration, location of Center of Gravity, etc.) The fact that trimming an aircraft will hold the same speed with changing power settings is an ancillary consequence of trim in so far as level flight is concerned. This trimming for ...

4

I think this anecdote bears directly on your question-- I often shoot downwind landings in winds up to 10 mph in a lightweight radio-controlled model airplane of tailwheel configuration. The key is to fly by reference to airspeed, not groundspeed. (One way to accomplish this in a radio-controlled model airplane, which lacks an airspeed indicator, is to ...

3

Airplanes are flown with respect to indicated airspeed; in terms of true airspeed, jets (and powerful turboprops) go faster and faster up to a point, and then they slow down a bit – that point is a crossover point: switching to an essentially constant Mach number. In a climb: As you wrote: the air density decreases, that means for a given IAS, the TAS ...

3

How does GS determine the time interval it takes for an aircraft to fly from the DP to the DEST, if TAS determines how the fast the aircraft is really going through the air. The simple answer to this question is when you calculate the time to fly from DP to DEST you need to use distance and velocity t = d/v. But d and v need to be referenced to the same ...

3

Essentially, they are selling a spoiler. The way they can claim "doubling the drag" may be as follows: The device spoils lift, thereby reducing lift cofficient. This results in the aircraft either having to fly faster to make the same lift, or at a higher AoA. Analysis of airfoil drag polars do show a sharp reduction of Lift/Drag ratio as AoA ...

3

The pitot tube measures pressure, not density. The pressure is not affected by the heating of the tube.

3

As already done in this answer, we can calculate the True Air Temperature (TAT) that the aircraft's skin will feel from the Static Air Temperature (SAT) and the Mach number: $$\frac{\text{TAT}}{\text{SAT}} = 1 + \frac{\gamma - 1}{2} M^2 = 1 + \frac{1}{5} M^2$$ (using $\gamma = 1.4$ for air). For different SATs the curves then look like this: I added a ...

2

The F-111 Aardvark could go Mach 1.2 at standard sea level conditions (14.7 psi and 59 deg F). I worked on the F-111 as a design engineer at General Dynamics / Fort Worth TX Division (where the F-111 was being built) in the late 1960s. At the time, the F-111 was the only aircraft in the world that could go supersonic "on the deck". Of course, it ...

2

Because you didn't read the text in the Wikipedia page above that equation ;-) That equation works for subsonic flow only because you have replaced the Mach number of the original TAS formula: $$\text{TAS} = a_0 M \sqrt{\frac{T}{T_0}}$$ with the formula of Mach number for subsonic flow:  M = \sqrt{\frac{2}{\gamma - 1} \left[ \left( \frac{q_c}{p} + 1 \...

2

A LOT of wind 3-5 times the speed, means 9-25 times the drag, as subsonic drag scales roughly with square of speed. Multiply that by the relative density of air at your cruising altitude. For 30000ft, that is 37.5% So: You would feel 3.4 - 9.4 times the wind drag / air rush. You might also notice the difference in wind chill factor. The -45C air will feel ...

2

You must use the same quantities for both speeds. Usually, this will be TAS. As you see, you are going to use a ratio of speeds: w/u. This ratio must be dimensionless, and furthermore, the quantities must be "compatible". For such purposes, you can't meaningfully divide IAS by TAS (or CAS), or, say, altitude by flight level, even though they are ...

2

The speeds in Boeing's table are consistent. To demonstrate that, we will have to know how to convert between Mach and CAS. There is no need to convert to true airspeed, the relation between CAS and Mach is well defined. Calibrated airspeed is purely based on impact pressure, which can be measured by a pitot-tube. For subsonic speeds: \$V_{CAS}=a_{0}\sqrt{5\...

1

The red zone in the graph is for high speed & load factor combinations, it is the zone where structural failure will occur. Trailing edge flap deflection is only allowed at limited airspeed, and the flap structural support is designed for those particular airspeeds only, with the usual structural safety margin of 1.5 of passenger aeroplanes (also ...

1

High performance aircraft (e.g. Airbus, Boeing, Gulfstream, etc.) will generally climb out at a specific IAS limited and based on regulatory requirements, altitude, and max efficiency (fuel/performance). Once the aircraft reaches a specific mach number (ratio to speed of sound, such as .78 or .82, etc.) as the climb continues the crew will continue ...

1

From a physics point of view (which may or may not agree with manufacturers’ terminology) a stall is when the angle of attack is steep enough that the airflow breaks away from the upper surface of the wing. Low airspeed is just what you would expect. In level flight at a known air pressure the relation between these two is well understood, but in other ...

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