Question of the day <----------------------

[Aerosoft Team [Inactive Account] 51558]

As the aircraft was guessed faster then I expected, a second question for the day.

I am circling the tower at Lelystad airport in my Carenedo Cessna. Trying to learn myself smoother and more controlled flight I am trying to keep the tower exactly at the same location under the wing (try that, you will find out it is very very hard). But the tower keeps moving in forwards. What should I do to keep it in the same location (and the same distance)?

There are two solutions and I want to hear both as doing them both would be the only correct way of solving this problem.

[VPA159 2]

If the tower creeps forwards relative to the wing, your bank angle is too steep. You need a bigger turn. If it's a left turn like in the pic, raise the left wing a bit. If you want to keep it in the exact same height relative to the wing, you need to descent a little too. Also, increase distance a tad to keep the distance the same.

Or the simple way: Land and park it in the correct distance next to the tower.

[Aerosoft Team [Inactive Account] 51558]

If the tower creeps forwards relative to the wing, your bank angle is too steep. You need a bigger turn. If it's a left turn like in the pic, raise the left wing a bit. If you want to keep it in the exact same height relative to the wing, you need to descent a little too. Also, increase distance a tad to keep the distance the same.

Or the simple way: Land and park it in the correct distance next to the tower.

Well but we said the distance would need to stay the same. You could change the bankangle and use rudder to get an ever growing uncoordinated flight attitude but that sort of defeats the whole idea, right.

[flyhigh 0]

Hi,

the rate of turn and the airspeed of the aircraft should be kept constant?

flyhigh

[VPA159 2]

Well but we said the distance would need to stay the same. You could change the bankangle and use rudder to get an ever growing uncoordinated flight attitude but that sort of defeats the whole idea, right.

I don't think so if you've, like I said, already descended "a little" and increased the distance from the tower with "a little minus something"(can't do the maths without the numbers ). Bigger turn radius but lower altitude to keep the distance the same as than in that picture. I think that'd work?

[LN-MAG 9]

Well, the wind might be the cause of the problem.. So do we need to take wind factors into consideration when answering this question?

[flyhigh 0]

Hi,

the rate of turn and the airspeed of the aircraft should be kept constant?

flyhigh

I forgot to mention that we must keep the same altitude as well if we are talking about coordinated flight. I also asume that this is meant to be in zero wind condition? If not then we should take the wind into account as well and compensate for it accordingly.

flyhigh

[mphilippi 0]

You have to increase right rudder, the left wing will move again into the direction of the tower.

Now you need to put your stick forward to prevent the aircraft from gaining attitude.

[VPA159 2]

You have to increase right rudder, the left wing will move again into the direction of the tower.

Now you need to put your stick forward to prevent the aircraft from gaining attitude.

Thereby side-slipping the plane? I think he answered no to that already.

If changing altitude isn't an option, then I'd suggest moving the aircraft a little bit more forward, in the direction of flight if the tower appears to be moving right/towards the front. Your turn could be perfect already, but the centre of the circle could be off the tower. The reason could be wind, or just bad aim when you began the circle.

[mikkel 63]

If it's moving forwards, I can only understand it as the yaw is a bit off, compared to the bank. I guess the only way to get it right is to constantly calibrate the curve with both rudder and ailerons, to both keep the aircraft at the same distance to the tower and have the wing point directly to the tower. But since you mention that you also want to keep the tower at the exact same spot _under_ the wing. I guess you would need to manipulate the speed, as I guess that different speeds will alter the amount of bank you would need to keep the distance to the tower. My FSX computer was left when I went home for Christmas, so I can not check it myself.

[LufthansaPilot 4]

Hey Mathijs,

you should really start a monthly/weekly contest where we can win aerosoft products, when we answer your question correctly

Back to your question:

1. Maintain Bank angle

2. use the rudder (to the right side), only in such an extent that it is possible for the Tower to stay under the wing

3. accelerate!

But to be realistic:

It is actually impossible to do what you have said, Mathijs?!

I mean it is Physically/mathematically just not possible, to maintain the distance to the tower...If you had tried it, you would relize that you would fly a so called "arithmetic spiral" (Archimedean spiral, named after Archimedes).

"It is the locus of points corresponding to the locations over time of a point moving away from a fixed point with a constant speed along a line which rotates with constant angular velocity. Equivalently, in polar coordinates (r, θ) it can be described by the equation

r=a+bθ

with real numbers a and b. Changing the parameter a will turn the spiral, while b controls the distance between successive turnings." *

EDIT: No wait!! It aint an archimedean spiral (or is it??) it is either a logarithmic spiral or hyperbolic spiral!

Oh my gash! Oh my gash! I'm so confused right now, I'm out...need to do something completely different. I'm going loopy...

*http://en.wikipedia.org/wiki/Archimedean_spiral

EDIT2nd:

Well I tried it now, at found out that it is actually possible...

I used the standard Cessna by Microsoft:

At first I decreased my speed to 48-50 knots and then extended the flaps to "Full".

The middle of the wingtip must stay with the middle of the tower!

Your aircraft must turn aroun the axis of the tower, and the middle of your wing must stay where the axis of the tower is, got it?

I don't know, If I was able to explain it with my poor english knowledge, there fore here is a picture of what I have tried to say:

a picture speaks more than a thousand words

You also need to use the rudder to be able to align the wingip with the axis of the tower.

[VPA159 2]

I think it IS possible. Try imagining an upside down cone, sharp end planted in the tower, circular end overhead. We agree that an aircraft is capable of making a perfect circle in the sky, maintaining a constant altitude? In a cone, every place in the circle/bottom is the same distance from the top. Also, where wind comes into consideration, you'd need to point the nose slightly into the wind to make the circle perfectly round. Very difficult, and if the purpose is to keep the tower at the same excact spot as observed from the plane, you'd actually need to sideslip some to compensate for any wind drift AND keep the altitude and circular pattern consistant AND keeping the tower appearing to be in the same spot.

[LN-MAG 9]

Okey, so my guess that the wind is causing the problem..

To fly a perfect circle around that point (the tower), you would need to compensate for the wind all the way around the circle. To do this you would need to have a steep bank angle when flying with tailwind and a shallower bank angle when you cross the opposite side of the circle flying directly into the wind.

To ease things up, let's say you enter the circle flying downwind.. Once abeam the point, you should immediately apply a steep bank angle to initiate your turn. As you progress with the turn, you should gradually decrease your bank angle as you are flying into more of a headwind and at the end of the first half of the turn, your bank angle should be at it's shallowest. When you fly the second half of the turn, you should gradually increase the bank angle and when you pass the point where you started off, your bank angle should again be at it's steepest. By using this method, you will manage to keep the aircraft at a constant distance relative to the tower when flying in windy conditions. Of course if there weren't any wind, your bank angle would be constant all the way around the turn. Also, in the upwind and downwind portions of the turn, the nose too will have to be progressively pointed into the wind by crabbing.

By doing this, I assume you would achieve a perfect circle. However, I'm not so sure that the tower will stay at the same place under the wing, if that was an important criteria..

That's my guess Hope that at least some of this makes sense as I've worked hard to find a solution

[Aerosoft Team [Inactive Account] 51558]

I think actually nobody got the right answer this time.

The maneuver is called 'on-pylon turns'. The problem is that the aircraft is above "the pivotal altitude".So the pilot will need to descend to the correct pivotal altitude or to increase speed to raise the pivotal altitude. Doing both a bit would of course be best. It's complex mathematics actually, but very well explained at http://www.av8n.com/...turns-on-pylon.

It's a total bitch to do it real smooth.