# Tag Info

12

There are at least two misconceptions in your question: The way I understand flex temperature is: It's a user interface for pilots to request a derating of engine power to reduce wear on the engine. This is not quite correct. A derating would imply that the engine thrust needs to remain at the derated level after an engine failure. A FLEX or assumed ...

7

A nautical ground mile is one nautical mile over the ground. A nautical air mile is one nautical mile through the air mass. This distance can be different because of wind. For example: If you are flying at 100 knots true airspeed in a zero wind condition, nautical ground miles will equal nautical air miles. However, if you are flying at 100 knots true ...

6

Air pressure reduces with altitude, so while an individual molecule is striking the the aircraft at 100kt, there are fewer of them. This means there is less pressure placed on whatever surface is being struck. The difference in indicated speed is simply one of a physical limitation with the air speed indicator - air speed indicators rely on dynamic pressure/...

5

Think of it this way. Your airspeed indicator is not directly measuring the distance traveled of any object, aircraft nor air molecules, over time. Your airspeed indicator is a pressure sensitive device that measures ram air pressure (dynamic pressure) versus static pressure. It converts that measurement into a meaningful value of airspeed. That ram air ...

4

Not really. First, the 'legal' reason: the flight manual doesn't offer this method. So you are not supposed to do it. Second, there is a technical reason: MiG-21 had so called 'floating flaps' (as they call it), which are held down only by hydraulic pressure. The pressure is set such that the air dynamic pressure would retract the flaps as the airspeed rises ...

4

How does the wind affect the net displacement of the aircraft...? Before we worry about the definitions of certain phrases such as "nautical air mile" and "nautical ground mile", we should learn to draw the vector triangle of (true) airspeed, wind, and groundspeed, assuming that the flight path, the earth's surface, and the wind are all ...

2

These are very strange terminologies. As far as aeronautics is concerned, we care about these things: Airspeed: speed of the aircraft relative to the local air-stream; this is important for keeping the airplane afloat Ground speed: speed of the aircraft relative to the ground; this is important for seeing how fast you may be getting from point A to B Maybe, ...

2

Although, I have never heard the term Nautical Air Mile, it does make sense. Based on your attached link, an NAM would be the distance from a particular parcel of air. Airspeed would be the speed at which the aircraft is moving through, towards or away from particular parcels of air relative to those parcels. Airspeed is also the speed at which parcels of ...

2

Yes, it can. As you say, that lowered thrust line adds to the lift requirement, but not dramatically so. I guess the technical term you mean is called downthrust. Together with sidethrust, this offset alignment of the propeller axis helps to reduce retrimming when thrust is changed. Downthrust has two effects: It increases the angle of attack on the tail ...

2

The thrust of a ramjet depends on the dynamic pressure of the airframe since this determines how high the pressure inside the ramjet can become. Thrust grows therefore initially with the square of speed. The efficiency of heat engines depends on the temperature and pressure ratio of their cycle, and again speed helps to improve that. The specific ...

2

Dynamic pressure is $$q = ½\varrho v^2$$ where $q$ is dynamic pressure, $\varrho$ is density and $v$ is velocity (a.k.a. true airspeed). The important bit here is that it is proportional to density and since density and pressure are closely related and pressure decreases with altitude, so does density For the intuition of particles hitting the surface, ...

1

TL-DR: IAS is not about speed but about dynamic pressure. You can read it as "This is how fast I would need to fly at sea level standard conditions in order to get the same dynamic pressure" As Jan Hudec pointed out already, indicated airspeed is computed from dynamic pressure. That itself is computed from total (i.e. stagnation) and static ...

1

There are other limits to engine operation as well as thrust and EGT temperature, for example maximum rotor speeds. Thrust is often limited in "hot and high" situations because the LP rotor can't run fast enough to push enough air through the engine to deliver maximum thrust. So "telling the FADEC the air is less dense than it really is" ...

1

No. MiG-21 (any modification) didn't need it and didn't have it. With its low-aspect-ratio delta wing and most mass concentrated in the centre, it was agile enough with standard ailerons. The elevator had a single hydraulic booster driving both halves of the stabiliser. Differential stabiliser was used on MiG-21's successor, MiG-23. That one had no ailerons ...

1

Service interval - is a maintenance term indicating the interval (either in time or number of flight cycles) between two successive services (e.g. inspection, change of oil, etc.) that a component requires. In case of UAVs this is not different. It can be for example that the Service Interval of the engine is 100 hours of flight time, meaning that the UAV ...

1

Thrust For a given fuel, ramjet thrust vs mach number trend may be approximately(see note 1) given by Thrust = flight mach number(sqrt(2000 / (air temperature * (1+(7 * flight mach ^ 2) / 40))) - 1) TSFC If we maintain a given air/fuel ratio, the amount of fuel consumed goes up linearly with mach, as air flow rate goes up with the same trend. Notes Note 1: ...

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