When I lower flaps, nose putches up??

Question

In my flight sim. Is this a real aircraft thing??

Answer 1

Yes it does. I’ll have to explain it gradually as many factors come into play here. What happens is that the wing has a point where all the lift is concentrated. This point is called the Centre of pressure( CP) or Centre of lift. In other words CP is the point where all the wings efforts are focused.

Now there is another point. The CG or Centre of gravity. This is a point that is the aircraft were suspended by a rod, it would balance. Ideally aircraft engineers want the CP and CG positions to be on the same point. But this is impossible. As fuel burns away, the CG shifts and your are not going to have the same load of passengers for every flight. So engineers just settle for a range of approved distances. To explain the relationship between CG and CP imagine a long cylindrical rod. If the rod is uniform, the CG will be exactly at the centre of it.

Imagine you balance this rod, exactly 1/2 the length from the nose.

Now imagine the CP is 3/4 of the length to the front. The CP creates an upward force. If you push the rod up the imaginary CP you notice it will pitch up. To keep the rod level, you need to push down on the tail. The same with an aircraft. To counteract this aircraft engineers came up with the horizontal stabilizer. This creates a downward force on the tail and keeps the nose down.

Now we can move on. CP is not a fixed point. As you increase the angle of attack it moves aft, as you decrease it, it moves forward. The same is true for a flap extension. As you extend the flaps, the CP will move to the rear. Some aircraft are more sensitive to this than others.

I tried to keep it as simple as possible, if you don’t understand something, message me. I’ll be more than happy to sort it out.

Answer 2

Yep. In most aircraft this is what happens because the flaps increase the lift coefficient of the wing which increases amount of lift created for equal speed. This is why you have to pitch the nose down to reduce the lift and slow the aircraft down.

I use flaps all the time to reduce speed! My 206 goes from 80mph to touchdown speed when I dump the last 20 on at short final and my 172 will go from 80kts to 55kts when I lower flaps to 40; all without touching the trim.

Remember, flaps allow you to touchdown (or lift off) at a slower speed; that is their only ultimate purpose.

Answer 3

Extending the flaps also increases the drag coefficient of the aircraft so, for any given weight and airspeed, flaps cause higher drag. Flaps increase the drag coefficient of an aircraft because of higher induced drag caused by the distorted planform of the wing with flaps extended

At higher speeds a negative flap setting is used to reduce the nose-down pitching moment. This reduces the balancing load required on the horizontal stabilizer which in turn reduces the trim drag


in other words yes its normal

Answer 4

Yes, real aircraft do exactly that. Flaps are designed to permit flight at low speeds by increasing the wing surface and increasing the lift. More lift means the nose goes up. When landing, you have to compensate by trimming the nose down.

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Answer 5

Yes - it happens in actual flight as well.

I presume you are lowering flaps on your landing approach. In this case, when the flaps start coming down, they initially generate lift, which tends to push the nose up, and once fully down steepen the glide approach.

In reality the nose needs trimming in both phases (taking off and landing) while raising or lowering the flaps.

Answer 6

Yep. Initially, the addition of flaps creates an increase in lift. Then, drag kicks in and the nose settles down, and the aircraft slows down.

Answer 7

For most aircraft, yes. In our Gulfstream, the horizontal stabilizer moves with the flaps to compensate for this. Most other aircraft require a couple of taps on the pitch trim chinamans hat.

Answer 8

Flaps do two things. Increase drag and increase lift at the same time. Now, the increase is drag isn't that important, it's more in the increase in lift. Lowering the flaps increases the camber of the wing. This increases the lift, causing the airplane to go up. then gradually go back down.

Now, a lot of people, including pilots, think that flaps are used to slow you down if you are going to fast...that's WRONG!!!

Yes, it does slow you down, but you don't use it for that purpose. Flaps are to be used for one primary purpose, have a steeper pitch angle without increasing your airpseed. So if you are high, and going 65 knots, you can put in your flaps, and point the nose down at a steeper pitch angle, and still be going at 65.

Answer 9

Yes it does - but as to why - so many wrong answers.

The correct answer is that the flaps cause the airflow to move downwards ACROSS the elevator (tail) - which then pitches the airplane nose up.

It's one reason some planes have tail surfaces high above the main wing !

Lowering flaps will also (sometimes) cause the airplane as a whole to balloon upwards - which is what a lot of the answers were really referring to.

Answer 10

When you drop a vertical slat along each wings trailing edge you create a huge amount of lift on the the wing which forces the nose up...