Aerobatics and Gates
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Gentleman
When I started this thread it was because in one of the most dreadful events in display history there was mention of an Aviation term I was unfamiliar with.
Since the age of about seven I wanted to fly Fast Jets with the RAF. It was not meant to be. Silly as it sounds it is true.
But, along with thousands like me, that does not mean I do not take an intimate interest in all things airborne.
I come on Pprune for a few things. One of them is the sheer professionalism of the men and women who fly and share their stories, memories and insights into one of the most demanding professions in the World.
The other reasons are the banter, the jokes and the sheer joy of people talking about doing something I was never privileged to do.
This thread is about Gates. What they are and what Pilots have to look out for.
Nothing more.
When I started this thread it was because in one of the most dreadful events in display history there was mention of an Aviation term I was unfamiliar with.
Since the age of about seven I wanted to fly Fast Jets with the RAF. It was not meant to be. Silly as it sounds it is true.
But, along with thousands like me, that does not mean I do not take an intimate interest in all things airborne.
I come on Pprune for a few things. One of them is the sheer professionalism of the men and women who fly and share their stories, memories and insights into one of the most demanding professions in the World.
The other reasons are the banter, the jokes and the sheer joy of people talking about doing something I was never privileged to do.
This thread is about Gates. What they are and what Pilots have to look out for.
Nothing more.
A comment has been made regarding the effects of power whilst looping. In the second half of a loop the height loss is a function of true airspeed and how much g is pulled. Speed will increase during this phase but there will be an optimum speed profile that gives the minimum radius; too slow and you are stall limited, too fast and you have to pull too much g. Therefore, a power reduction may be required at the top of a loop in order to minimise height loss.
Personally, in a straight loop in the Hunter I will use full power on the way up to gain as much energy as possible but once the nose passes down through the horizon at the top I throttle back to a mid range power setting to keep the speed down, not just to control the radius but also to give me the speed I require for the next manoeuvre. I have a philosophy that I want the stick coming forwards towards trim as I approach base height (ie progressively reducing g) so that I have height in hand if necessary and if I still had full power this would result in a significant increase in speed on exit which I may not want.
There are some 'looping' manoeuvres in my Hunter display during which I select idle, but these start with either lots of speed or lots of height. Specifically, a reverse 1/2 Cuban entered at 500 KIAS (starting manoeuvre) and the downward half of a vertical 8 (final manoeuvre), commenced at a gate of 9000 ft following a vertical roll as a final manoeuvre.
There are lots of different ways of 'looping' high speed aeroplanes. What I have said above is how I do it but others have equally valid but different strategies which I certainly would not criticise.
Personally, in a straight loop in the Hunter I will use full power on the way up to gain as much energy as possible but once the nose passes down through the horizon at the top I throttle back to a mid range power setting to keep the speed down, not just to control the radius but also to give me the speed I require for the next manoeuvre. I have a philosophy that I want the stick coming forwards towards trim as I approach base height (ie progressively reducing g) so that I have height in hand if necessary and if I still had full power this would result in a significant increase in speed on exit which I may not want.
There are some 'looping' manoeuvres in my Hunter display during which I select idle, but these start with either lots of speed or lots of height. Specifically, a reverse 1/2 Cuban entered at 500 KIAS (starting manoeuvre) and the downward half of a vertical 8 (final manoeuvre), commenced at a gate of 9000 ft following a vertical roll as a final manoeuvre.
There are lots of different ways of 'looping' high speed aeroplanes. What I have said above is how I do it but others have equally valid but different strategies which I certainly would not criticise.
I don't really want to drag out the F16 thing, and not on the shoreham thread, but I am now a bit confused.
If I understood the gate issue correctly, surely it is the height and speed at the top of the loop/split s which is key - and at that point the gates are probably very similar in that the energy/height margins are all about the remaining 1/2 of the loop move from 12 o'clock to 6. Infact at this point difference between split s, loop and 1/4 clover are pretty much all irrelevant? Wasn't it a reverse half cuban 8 anyway?
I am confused about your explanation though Ken. Either he had pre breifed the gate correctly at 2500ft for mountain home vs 1680ft at nellis, or he hadn't? Which is it? I understood it (maybe incorrectly) that he had misbriefed at 1680ft and flown to 1680ft. But you suggest he breifed at 2500ft and momentarily flew on 'autopilot' at his familiar 1680ft by mistake? Lots of human factors here but isn't that actually, technically, missing the gate? Is this gate actually at the roll of the reverse half cuban or at the top (12 o clock)? 1680ft seems quite low anyway unless it is related to the roll. I guess the roll to inverted initiation at 45deg is one of the key points in this move, at the apex you are just checking you did the pull up correctly.
If I understood the gate issue correctly, surely it is the height and speed at the top of the loop/split s which is key - and at that point the gates are probably very similar in that the energy/height margins are all about the remaining 1/2 of the loop move from 12 o'clock to 6. Infact at this point difference between split s, loop and 1/4 clover are pretty much all irrelevant? Wasn't it a reverse half cuban 8 anyway?
I am confused about your explanation though Ken. Either he had pre breifed the gate correctly at 2500ft for mountain home vs 1680ft at nellis, or he hadn't? Which is it? I understood it (maybe incorrectly) that he had misbriefed at 1680ft and flown to 1680ft. But you suggest he breifed at 2500ft and momentarily flew on 'autopilot' at his familiar 1680ft by mistake? Lots of human factors here but isn't that actually, technically, missing the gate? Is this gate actually at the roll of the reverse half cuban or at the top (12 o clock)? 1680ft seems quite low anyway unless it is related to the roll. I guess the roll to inverted initiation at 45deg is one of the key points in this move, at the apex you are just checking you did the pull up correctly.
Last edited by JFZ90; 27th Aug 2015 at 14:52.
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I am confused about your explanation though Ken. Either he had pre breifed the gate correctly at 2500ft for mountain home vs 1680ft at nellis, or he hadn't? Which is it? I understood it (maybe incorrectly) that he had misbriefed at 1680ft and flown to 1680ft. But you suggest he briefed at 2500ft and momentarily flew on 'autopilot' at his familiar 1680ft by mistake?
