PPRuNe Forums - View Single Post - Constant radius turns around a ground feature
Old 21st February 2006 | 11:33
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delta3
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Joined: Apr 2004
Posts: 461
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From: Belgium
Constant radius

Sorry guys, I read a lot of answers but I may seam to disagree (unless I didnot read carefully enough)

Bank angle is a combination of two things

- a simple relation between ground speed and radius
- a drift effect because of side component

Take the following 4 cases.

1. upwind
- no side effect
- slower GS so smaller AoB

2. downwind
- no side effect
- higher GS so higher AoB

3. cross wind
- GS-IAS, so no effect
- side wind will make that your HDG will lag the track, so that you will have to make a yaw of more than 90° in the next 90° of ground track : so in the first 90° we turned inertially only for instance 80°
- so banking will build up

4. base
- GS-IAS no effect
- side wind effect will require you to turn heading by more then 90° in the first 90° of ground track, so in first 90° we will turn inertially 100°
- so banking decreases


So I would say banking is greatest downwind and least in up wind

Now turning perfect circles (drift offset) is still different from keeping the centre point at the same spot and is more difficult because in that case all 4 quadrants have different aspects.

A good way to test is try this in 40 knts, and look at the GPS track you manage. Getting circles is not easy...


My 2 cents worth
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