# Tag Info

Accepted

### Why did my flight climb so sharply on takeoff?

Your flight took off during a storm. During a storm, the wind speed close to the surface of the earth is much lower than the wind speed a bit higher up. This variation of wind speed over a short ...
• 83.5k
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### Does lift equal weight in a climb?

It depends on exactly how you define "lift" and "weight". You might say intuitively that lift is all the forces acting on the aircraft in the upward direction, like this: In this case, lift must ...
• 1,073

### Why aren't takeoff flaps used all the way up to cruise altitude?

The image below from this answer shows characteristics of airfoils with flaps. As you rightfully concluded, lift ($C_{L_{max}}$) goes up with the deployment of flaps, but the drag also goes up and ...
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### Does lift equal weight in a climb?

In an aircraft that is climbing at a constant vertical velocity, the total of the upward-directed vertical forces is the same as the total of the downward-directed vertical forces. Were it not so, ...
• 11.1k
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### How long did the SR-71 take to get to cruising altitude?

According to the performance data in the manual it takes 19.9 minutes to get to 70,600 feet. Refueling time will depend on how much fuel is needed for the mission as well as how long it takes to ...
• 101k

### Why aren't takeoff flaps used all the way up to cruise altitude?

This is a good question, and I don't feel the other answers get at the essential part which is: Is it optimal to climb with the flaps deployed? As with any optimal question, the answer relies on what ...
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### Does lift equal weight in a climb?

Short answer: No. Long answer: When the flight path is not horizontal, lift will not be vertical but perpendicular to the direction of motion (in still air). Thrust will also have a vertical ...
• 233k

### Why did my flight climb so sharply on takeoff?

Sometimes a departing airplane will receive or be offered an accelerated climb profile from ATC which gets it up and out of the published approach and departure patterns quickly. If the pilot elects ...
• 21.3k
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### What is the difference between rate of climb and climb gradient?

The climb gradient is the percentage of the rise over run (100% if you are climbing at 45 degrees) that your aircraft is climbing at while the rate of climb is the speed at which you are climbing ...

### A plane is flying at constant velocity in equilibrium, then pitches up. What happens?

A step increase in elevator (which is then held) will first upset the pitching moment equilibrium of the aircraft -- the pitching moment will be non-zero. It will pitch nose up, increasing angle of ...
• 12.5k
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### Why do flaps retract?

Flaps retract in order to reduce wing area. This has several advantages when flying fast: The higher wing loading (weight per lift-producing area) reduces gust loads. When hit by a vertical gust, the ...
• 233k

### How do you calculate the ground distance in a climb?

One key point that has not been explicitly mentioned so far, though it's apparent from the example given in another answer, is that for light piston-engine airplanes, the angle of climb is so shallow ...
• 22.7k
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### PoH says airplane climbs steeper at higher weight. Why? How?

There are three stages to a short field takeoff over an obstacle- the ground roll, where the airplane accelerates to the minimum airspeed necessary to leave the ground, a period of further ...
• 15.9k
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### How should I read these climb and descent profile notations?

For the climb profile, the first two values are indicated airspeed -- below 10,000 and above 10,000 feet MSL, and the final value is a Mach fraction. So 250/280/78 would be a climb of 250 knots below ...
• 51.8k

### What is the difference between rate of climb and climb gradient?

A climb gradient is a geometry problem -- the relationship of two points in 3-dimensional space... to get from one to the other you gain X' in Y NM, so you have X/Y feet per nautical mile as a climb ...
• 51.8k

The gradient of climb is the ratio of the increase of altitude to horizontal distance through the air, not over the ground. The definition used by the UK CAA in CAP 698 is: Climb Gradient ...
• 54k

### Does lift equal weight in a climb?

If we define lift as the component of the total aerodynamic forces on the aircraft that is perpendicular to its direction of motion, then lift will be slightly smaller in a stable climb. It is ...

### What is the optimal way to climb fastest between two points on a Cessna 172N?

Aircraft drag scales with the power of speed. This by itself should make clear that deviating from the point of optimum performance will always incur higher losses which cannot be made up for later. ...
• 233k

### What is the optimal way to climb fastest between two points on a Cessna 172N?

Ron nailed it. (See comment on OP.) It depends on what you’re trying to achieve. Climbing “fast” in terms of maximum vertical speed = Vy (best rate) If the noise sensitive zone is immediately ...
• 6,016

### Is thrust larger than weight in a vertical climb?

Yes, thrust force vector must have a force equal to (but opposite) the combined gravitational force and aerodynamic drag force (from velocity) to climb at constant speed. In horizontal flight, thrust ...
• 20.5k
Accepted

### Why doesn't the flight path angle increase beyond a certain angle even if the angle of attack is increased?

If you keep increasing your angle of attack, your drag will increase and combined with the increasing along trajectory component (your path angle will increase) of the weight vector will slow you down ...
• 83.5k

### Climb Performance

So, 5,000 feet to gain and you're climbing at 750 ft/min. At that rate it would take 5000/750=6.67 minutes (to 2 decimal places) to make it. A speed of 90 MPH is 1.5 miles per minute. Thus 10 miles ...
• 39.2k

### Why did my flight climb so sharply on takeoff?

It appears that it took the pilot about 15 mins to climb from near sea level to FL370. That's a climb rate of about 2500 feet/min, which is a pretty modest climb rate for a jet. If you're looking ...
• 73.8k

### Why aren't takeoff flaps used all the way up to cruise altitude?

Because it would not be efficient. Flaps increase drag (and lift), so you would burn more fuel climbing to cruise altitude with flaps extended compared to if if you retract them.
• 36.6k

### What are the climb rates during the different phases of flight of an A320?

According to the EUROCONTROL Performance Database, the usual climb rates and speeds for an A320, for ATM purposes, are those depicted on the image below: Source: https://contentzone.eurocontrol.int/...
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### How is the airspeed-Mach number transition handled in modern airliners?

The transition happens around FL260 at which the Mach Maximum speed of the plane, intersects with the Maximum speed IAS of the plane. For example if the maximum IAS Speed is 300 knots, and maximum ...
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### How much altitude can a glider gain only from losing speed?

You can calculate a theoretical maximum (which will be well above the actual practical height gain) by considering the conversion of kinetic to potential energy. You can also make estimates based on ...
• 4,502