Maximum angle of descent
Bellwether&cloudbuster
Joined: Mar 2007
Posts: 269
Likes: 0
From: Bristol UK
30/60/60
30 degrees one direction, then a 60 degree turn to be 30 degree pointing away from track in the other direction then a 60 back again so no more than 30 degrees off the track at anyone time.
30 degrees one direction, then a 60 degree turn to be 30 degree pointing away from track in the other direction then a 60 back again so no more than 30 degrees off the track at anyone time.
Joined: Jan 2006
Posts: 2,205
Likes: 0
From: US
Jump in a simulater and 'freeze' several positions(altitude/distance to runway).
Try both techniques.
Report back with results.
I'd vote for speed/speedbrakes farther out, configuration in close.
Good luck defining 'farther out' and 'in close' (it's called experience and judgement IMO).
Try both techniques.
Report back with results.
I'd vote for speed/speedbrakes farther out, configuration in close.
Good luck defining 'farther out' and 'in close' (it's called experience and judgement IMO).
Joined: Oct 2000
Posts: 436
Likes: 0
From: N. Europe
Imagine sitting at point A, early on the STAR. Whoops, shortcut by ATC, all of a sudden you are high.
Assume you just get as draggy as possible, reduce to idle and then plod along without increasing speed significantly. You will end up at point B at a certain altitude dictated by your L/D ratio at that airspeed.
Imagine instead that you get as draggy as possible, reduce to idle and increase the speed as much as you are allowed by pointing the nose down. At the altitude of point B you level off and fly to point B.
The name of the game is to get rid of energy. Which method will have you slowest by point B? That method is the most effective in getting rid of energy in the number of track miles between A and B.
With the second method, where you increased speed, you will fly a longer distance A to B and at a higher speed, meaning increased drag compared to just flying the straight path (the backside of the power curve is not likely to be seen in that phase of flight).
Energy loss equals drag times distance covered. You will have less energy (i e lower airspeed) at point B if you pitched down to increase speed. If you instead only levelled off to the initial airspeed and then descended at this airspeed, you'd be lower at point B using the second method.
Every glider pilot is well aware of this. If you are way high, pop the boards and dive for the ground.
Assume you just get as draggy as possible, reduce to idle and then plod along without increasing speed significantly. You will end up at point B at a certain altitude dictated by your L/D ratio at that airspeed.
Imagine instead that you get as draggy as possible, reduce to idle and increase the speed as much as you are allowed by pointing the nose down. At the altitude of point B you level off and fly to point B.
The name of the game is to get rid of energy. Which method will have you slowest by point B? That method is the most effective in getting rid of energy in the number of track miles between A and B.
With the second method, where you increased speed, you will fly a longer distance A to B and at a higher speed, meaning increased drag compared to just flying the straight path (the backside of the power curve is not likely to be seen in that phase of flight).
Energy loss equals drag times distance covered. You will have less energy (i e lower airspeed) at point B if you pitched down to increase speed. If you instead only levelled off to the initial airspeed and then descended at this airspeed, you'd be lower at point B using the second method.
Every glider pilot is well aware of this. If you are way high, pop the boards and dive for the ground.
Joined: Jan 2000
Posts: 511
Likes: 2
From: South Africa
Energy loss equals drag times distance covered. You will have less energy (i e lower airspeed) at point B if you pitched down to increase speed. If you instead only levelled off to the initial airspeed and then descended at this airspeed, you'd be lower at point B using the second method.
Every glider pilot is well aware of this. If you are way high, pop the boards and dive for the ground.
Every glider pilot is well aware of this. If you are way high, pop the boards and dive for the ground.
Getting gear and flaps and speedbrakes out beats the drag of speedbrakes plus drag increase from higher speed. Every glider pilot does not have the huge amount of form drag that you can introduce on an airliner.
But you may well be right. I just found that inside the TMA, slow and dirty works better than fast, clean and decell.
It has the added advantage of not stressing to make the slot.
Joined: Oct 2000
Posts: 436
Likes: 0
From: N. Europe
Getting gear and flaps and speedbrakes out beats the drag of speedbrakes plus drag increase from higher speed. Every glider pilot does not have the huge amount of form drag that you can introduce on an airliner.
Then there are those other factors as well, as you rightly point out. If you just get draggy and keep your speed, you will have a nice stable ride and avoid those speed changes. Chances are the benefits outweight the potential energy loss benefits of diving... especially in the TMA. It may well be better - but the maximum angle of descent of the thread title it won't be.
