How would an aircraft react with different wind conditions(given in the 'details' section)?

Question

1)If groundspeed of aircraft is 80knots,and direct tailwind is 120knots.Which direction would a flag, hypothetically kept over the fuselage of the aircraft,fly ?

2)If groundspeed is 100knots and a DIRECT crosswind is of 100knots.

3)If aircrafts maximum speed on full throttle is 120knots and there is a 150knots direct headwind?

Answer 1

1) Towards the tail of the aircraft.

2) The aircraft would drift drastically in the direction of the cross wind.

3) The aircraft will fly backwards at 30 knots.

Answer 2

1)  Aft.

2)  Aft.

3)  Aft.

Answer 3

1) It’s not possible to have a ground speed slower than the tailwind, unless the airplane is on the ground (in which case the flag would point forward), because the airplane pushes or pulls on the air in flight (except for air inside jet exhaust).

If it pushed on the 120 knot tailwind, it would go 120 knots plus the normal speed of the aircraft, ground-speed wise.

However, if the aircraft normally travels say 80 knots, then the flag would experience an 80 knot headwind, thus pointing aft; but it would travel over the ground at 120 knots.

In the case if there was no tailwind and in a short amount of time, a 120 knot tailwind developed, the airplane would suddenly read 0 on the airspeed indicator, the flag would point forward, and it would fall very quickly out of the sky.

2) If the aircraft is traveling forward at 100 knots, with a crosswind at 100 knots, it would be crabbed sonically into the wind so it would keep traveling forward at 100 knots.

However, it's impossible to determine the angle of the crab without airspeed, because if the airplane is traveling 100 knots airspeed, then it would not be able to travel forward 100 knots groundspeed in a 100 knot crosswind. It would both be pointed directly into the wind and have no relative movement, drift hopelessly or backwards even over the ground.

If it was traveling something like 200 knots airspeed, then it could be crabbed at like a 30 degree angle and travel forward 100 knots groundspeed. In a coordinated flight, the flag would point aft, because as the airplane travels forward in a crab, the airframe is streamlined into the wind, and the effect is like a direct headwind.

Imagine balls being thrown at the side of a moving boat, if it was pointed forward, the balls would hit the side of the boat.

If the boat was pointed somewhat into the direction of the balls (e.g. a crab), then the balls would hit the front of the boat, and any ball traveling at its side will be unable to hit the boat as the boat moves forward and the rear of the boat becomes relatively farther away from the ball.

3) If the airplane is traveling at 120 knots airspeed into a 150 knots headwind, it will have an effect on the airplane as traveling 120 knots into the wind. Thus the flag is pointed aft.

However, the airplane will travel backwards at 30 knots groundspeed.

If the airplane was sitting in a calm wind and 150 knots of headwind developed, it would quickly take-off vertically and backwards relative to the ground without engine power, but become subject to the wind's will and quite be unstable.

Think of what happens when you move a car behind a jet engine (you can get category 5 hurricane winds behind a jet at full power up to 300+ feet away).

Answer 4

1. THE FLAG IS FLYING HIGH AND FAST FORWARD. IT MIGHT GO A LITTLE TO THE L/H OR R/H SIDES OF THE FUSELAGE, BUT THAT FLAG IS POINTING, POINT FORWARD. TAIL WIND IS HIGHER THAN GROUND SPEED. TRY THIS TRICK IN YOUR CAR.

2. IT WOULD BE A LITTLE SHAKY. BUT NO MORE THAN NORMAL. ITS ABOUT EVEN PRESSURE

3.WHAT IF YOUR CAR WAS GOING 55 MILES PER HOUR AND YOU HAD WINDS UP TO 85 MPH. I THINK YOU FIGURE THIS OUT ON YOUR OWN.

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OK JOHN B STUPID, THIS GUY IS TALKING ABOUT GROUND SPEED. MORON.

Answer 5

That is all very simple math... you don't even need the circular sliderule for those and you need to be able to do those problems in your head if you hope to be a competant pilot.

1) 80+120= 200 Kts

2) A the crosswind component is 1.1 PERCENT per DEGREE.. so a 100 percent crosswind componen would be 90 degrees and 100 knots... and if you want to know what the effect will be, THEN you need to be able to use a circular sliderule or navigational computer because you can't do this with plain math.

3)  Use no flaps and use ground effect to fly out... the plane will fly because the headwind is 30 knots over V3,  BUT anyone flying into a headwind of 150 knots is NUTS and anything can happen because nobody can hold a plane in those conditions at full throttle, you may fly but you may not fly very far.

Answer 6

Hahahaha. You guys kill me. A flag attached to an aircraft will ALWAYS fly straight back as long as the aircraft is in coordingate flight. An airplane in flight has no clue what the wind is. It simply cant see the earth as it drifts. c'mon John C wind's effect on an airplane is not even close to its effect on your car. I know, I know. You guys still don't get it do you? Jeez.

Answer 7

Dear Eager:

1)  Either this is a trick question or you need to go back and take a look at the meaning of the word "groundspeed."   It is not possible to have a tailwind that is greater than the ground speed.  If you had a tailwind of 120 kts and a ground speed of only 80 kts, then the airplane would be flying backward at 40 kts, which would be sort of pointless even if it were physically possible.

There are some high-performance helicopters that can probably do it.

Assuming it is a trick question and you are imagining a backwards-flying airplane, then the flag would be streaming toward the front end of the airplane, helicopter, flying saucer or whatever.

(Or does a flying saucer have a front end?)

If you actually meant "airspeed" instead of "groundspeed," then the ground speed would be 200 kts and the flag would be streaming to the rear as it normally would.

2)  Flag would stream to the rear and maybe off to one side at an angle that cannot be determined from the available information.  Ground speed is given, but that does not determine the effect of wind triangulation.

3)  You would have a negative ground speed of -30 kts, and the flag would stream to the rear.

Answer 8

John B got it.  The thing you have to remember is that the aircraft moves relative to the air (pushes against the air, not the ground like a car).  In coordinated flight the flag always points straight back toward the tail.  Some gliders have slip indicators that are a string on the canopy.  In coordinated flight the string points straight backwards.

Also, you seem to have a confused idea of groundspeed.  You can't have a groundspeed that is lower than the tailwind.  I assume you must mean that the TAS is 80 kts, which gives a 200 kts groundspeed.