Executing a 1G barrel roll?
One understands that the secret of a well executed barrel roll is to ensure that one gets the nose high enough to start with and have due consideration for ones' wingmen:
At this point a simple training aid may help;; use the centre cardboard tube from a bog-roll,or kitchen roll; highlight the `skewed join line` along the tube; from one end draw a little aircraft symbol in the `direction highlighted`.
Draw further symbols at each 90 deg position around the tube,and along it`s length....You should now have a `corkscrew` flightpath,for either a LH/RH barrel roll.
Henry Crun`s diagram is probably taken from AP129,and is incorrect,in that the symbols of the aircraft are 90 deg. out.
At position `D`(6 o`clock) the aircraft is at the lowest point in the roll,with wings level; at `A` the aircraft is at the wings vertical position and climbing at about 45-60 deg nose-up; at the position `B`the aircraft is wings level,inverted, nose above the horizon,just maintaining `positive G`,but still rolling,and then position `C` is 90deg wings vertical,and so on...
The critical point is at the top of the barrel,as noted by NoD,that the wings should be level,and the nose above the horizon; if not, you can end up in serious `crap`....
Now you can look at your `Blue Peter` aid and see where the heading and pitch attitude should be at any point around the barrel.
For an `outside view`,go to YU-TUBE,and search `tonneau barrique d`un Transall`.Another couple of videos,search for `piloted by Sobolev`....
I should add that depending on your aircraft type ,one can get away with about 2G pull at the start,and `float` over the top....(with practice !)
If you want to see `how not to do it, then search for `Biggin Hill Invader crash`...
Draw further symbols at each 90 deg position around the tube,and along it`s length....You should now have a `corkscrew` flightpath,for either a LH/RH barrel roll.
Henry Crun`s diagram is probably taken from AP129,and is incorrect,in that the symbols of the aircraft are 90 deg. out.
At position `D`(6 o`clock) the aircraft is at the lowest point in the roll,with wings level; at `A` the aircraft is at the wings vertical position and climbing at about 45-60 deg nose-up; at the position `B`the aircraft is wings level,inverted, nose above the horizon,just maintaining `positive G`,but still rolling,and then position `C` is 90deg wings vertical,and so on...
The critical point is at the top of the barrel,as noted by NoD,that the wings should be level,and the nose above the horizon; if not, you can end up in serious `crap`....
Now you can look at your `Blue Peter` aid and see where the heading and pitch attitude should be at any point around the barrel.
For an `outside view`,go to YU-TUBE,and search `tonneau barrique d`un Transall`.Another couple of videos,search for `piloted by Sobolev`....
I should add that depending on your aircraft type ,one can get away with about 2G pull at the start,and `float` over the top....(with practice !)
If you want to see `how not to do it, then search for `Biggin Hill Invader crash`...
Last edited by sycamore; 9th Jan 2011 at 11:52.
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Surely Henry's picture should show the horizontal axis of the roll set at some 10 - 15deg above the horizon so as to cope with the inevitable fall through that would otherwise require the recovery action so clearly pointed out by NigelOnDraft.
The way I was taught in the Bulldog was to be aligned on your chosen line-feature, drop the nose and bank 45' away from the direction of intended roll, then reverse the direction of roll into the maneuvre and commence the pull, thus establishing on the profile at the half past four or half past seven point,nose lowand rising with 45 deg bank and ensuring that wings level occurred at least 10deg above the horizon. That in turn should ensure wings level inverted on the other side and still with nose appreciably above the horizon - or else chuck it away as NOD describes. The BIG briefing point was nose 10' above the horizon at wings level pitching up to ensure a safe pitch attitude when inverted.
It might be different in a fast jet, but that works in a light single, or at least, as I recall it.
The way I was taught in the Bulldog was to be aligned on your chosen line-feature, drop the nose and bank 45' away from the direction of intended roll, then reverse the direction of roll into the maneuvre and commence the pull, thus establishing on the profile at the half past four or half past seven point,nose lowand rising with 45 deg bank and ensuring that wings level occurred at least 10deg above the horizon. That in turn should ensure wings level inverted on the other side and still with nose appreciably above the horizon - or else chuck it away as NOD describes. The BIG briefing point was nose 10' above the horizon at wings level pitching up to ensure a safe pitch attitude when inverted.
It might be different in a fast jet, but that works in a light single, or at least, as I recall it.
Do a Hover - it avoids G
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IMO Henry's diagram is perfect - so far as it goes What he misses is that you pass through A in a recovery from a preceding dive. Yes you are wings level at this point but you do need about 2 g at the same time. As BOAC says you are doing a (low g) twisted loop. Indeed it is the twisted bit that allows you to loop at such a low g without running out of airspeed.
Re accidents during barrel rolls at airshows when I was a CAA display authorisation examiner I used to fail anybody doing a barrel roll along the display line unless they started it rolling TOWARDS the crowd. This is because the roll only goes wrong in the second half and if you start it towards the crowd then during the nasty second half you will be pulling and travelling away from the crowd as you woosh into the deck.
Re accidents during barrel rolls at airshows when I was a CAA display authorisation examiner I used to fail anybody doing a barrel roll along the display line unless they started it rolling TOWARDS the crowd. This is because the roll only goes wrong in the second half and if you start it towards the crowd then during the nasty second half you will be pulling and travelling away from the crowd as you woosh into the deck.
A-B, correct; if you take your `B-P` kitchen roll,and set the `start at about4/8 o`clock,to build speed in a dive,and look `thru` the tube , the centre axis should be ` always above,seldom level,never below ` the horizon.. if the axis is below,the aircraft will have the nose below,and that is `chicken -time`,ie push ,roll upright`,and take a deep breath..
There is another video taken from inside the Transall,somewhere on Y-T, but they don`t show the wine pouring..!
There is another video taken from inside the Transall,somewhere on Y-T, but they don`t show the wine pouring..!
This is because the roll only goes wrong in the second half
All vertical or semi-vertical manouevres occur in the initial pull-up. The second part which kills people is merely a consequence.
Sorry, but too many ignorant
amateurs around .......
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Quote:
This is because the roll only goes wrong in the second half
Too damn right John.
All vertical or semi-vertical manouevres occur in the initial pull-up. The second part which kills people is merely a consequence.
This is because the roll only goes wrong in the second half
Too damn right John.
All vertical or semi-vertical manouevres occur in the initial pull-up. The second part which kills people is merely a consequence.
Most accidents I have read about seem to occur at the edge of the air, where the sky runs out and the terrain begins.
Aerobatics aficionados might enjoy this video of Bob Hoover with some interesting dead stick manoevres and where he pours a glass of iced tea while executing a barrel roll.
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henry crun,
Position's A/B/C/D mark the position of the left wingtip in a barrel-roll to the right; A/B/C/D would mark the position of the right wingtip in a barrel-roll to the left assuming the image was mirrored I guess...
John Farley,
You mean you're pulling out of the dive after finishing the barrel-roll?
Position's A/B/C/D mark the position of the left wingtip in a barrel-roll to the right; A/B/C/D would mark the position of the right wingtip in a barrel-roll to the left assuming the image was mirrored I guess...
John Farley,
IMO Henry's diagram is perfect - so far as it goes What he misses is that you pass through A in a recovery from a preceding dive.
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From a fellow air-tourer dancer
Dear Air Tourer, you (and you, too, Agaricus bisporus, just as well) describe the same technique that I laboured to develop to achieve a positive-G manoeuvre in a 100 hp Victa, that you could put your dear ol' mum through (done) with her eyes shut, but then the second time ask her to now open her eyes 'at the top.' Frabjous fun, if you have the right mum/friend/victim. Otherwise hysteria results. Pick your 'victim' carefully.
The trick is not to achieve one-G. It is really to manage energy/ flight-path to achieve 'never-negative-G'. (Simple engines keep running then.)
This whole discussion really boils down to how much energy your aeronautical device has, how much drag, how much (sic) wing loading, how much (sic) velocity, roll rate, aileron drag, etc etc.
Our discussion's we-*can-vary-the-rifle-bore military grunters can essentially point and do, as can our (magically)-excessively-powered competition aero-comp friends. Vertical hover, anyone?
We lower-order growths have to do with making the best of what we have, and what we have/had determines how you carve that bit of air, and whether you do it for your own bottom's pleasure, or for an audiences’.
Self taught (Aerobatics? Now? Dear, you've just gone solo!) much later I was having doubts about my BRs, and asked B.T. (and ancient tiggy-moth displayer of note) to help me out (my only aerobatics instruction ever: shock) and he finished up throwing his hands in the air (litterally) & giving up (on the Victa).
Yet he could carve the most exquisite aeros in a Tiger. But that was another technique altogether.
As me dear old (still firing) mum would say, "Whatever takes your fancy, said old Mother Clancy, as she kissed the cow."
Good Lord!
That's disgusting. I thought *we* invented that sort of thing. . . .
Barrel rolls, you awful minded person you. Barrel rolls.
The trick is not to achieve one-G. It is really to manage energy/ flight-path to achieve 'never-negative-G'. (Simple engines keep running then.)
This whole discussion really boils down to how much energy your aeronautical device has, how much drag, how much (sic) wing loading, how much (sic) velocity, roll rate, aileron drag, etc etc.
Our discussion's we-*can-vary-the-rifle-bore military grunters can essentially point and do, as can our (magically)-excessively-powered competition aero-comp friends. Vertical hover, anyone?
We lower-order growths have to do with making the best of what we have, and what we have/had determines how you carve that bit of air, and whether you do it for your own bottom's pleasure, or for an audiences’.
Self taught (Aerobatics? Now? Dear, you've just gone solo!) much later I was having doubts about my BRs, and asked B.T. (and ancient tiggy-moth displayer of note) to help me out (my only aerobatics instruction ever: shock) and he finished up throwing his hands in the air (litterally) & giving up (on the Victa).
Yet he could carve the most exquisite aeros in a Tiger. But that was another technique altogether.
As me dear old (still firing) mum would say, "Whatever takes your fancy, said old Mother Clancy, as she kissed the cow."
Good Lord!
That's disgusting. I thought *we* invented that sort of thing. . . .
Barrel rolls, you awful minded person you. Barrel rolls.
Henry et al, that is a picture that even goes back to the 1940`s,and perpetuated in AP129,but it is still wrong. The lift vector `L`,always should point to the centre axis of the `barrel`. You can do it as per the diagram,but can end up `tent-pegging`,as many have......,if at low-level.....
Actually if you look at the Transall video,the pull-up is started wings-level,and then at about 35-40 deg. N-U,aileron is fully applied,as applying full aileron at max `G` is not a good idea in such a large,long-span aircraft,but the rest looks good,also having the benefit of airbrakes reduces the speed/G/ roll in the latter part of the manoeuvre..
There is/was a heavy discussion on the `Flypast` website,of a photo supposedly showing a Dakota doing a barrel roll,but no-one actually produced the photo....Syc..
Actually if you look at the Transall video,the pull-up is started wings-level,and then at about 35-40 deg. N-U,aileron is fully applied,as applying full aileron at max `G` is not a good idea in such a large,long-span aircraft,but the rest looks good,also having the benefit of airbrakes reduces the speed/G/ roll in the latter part of the manoeuvre..
There is/was a heavy discussion on the `Flypast` website,of a photo supposedly showing a Dakota doing a barrel roll,but no-one actually produced the photo....Syc..
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Last edited by sithfighter; 10th Jan 2011 at 17:57.
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The maneuvre pulled by the Transall is not what I'd call a BR in the classic sense, rather a low G ballistic roll of some kind. No way you could draw that around a bog-roll unless you trod on one end first. That biig pullup before the roll input and subsequent looong rolling pullout are neither symmetrical, elegant nor barrel-shaped. Looks about as natural as a cow dancing to me. Impressive, certainly. Foolhardy, probably. Barrel roll? Non.
I'm curious about the technique that commences the "BR" from level or nearly level flight. That must surely result in the roll itself being flown on an axis about 45' to the original line of flight and thus with a zig-zag ground track and the entry and exit tracks substantially offset. Goofing around apart, are aerobatic maneuvres not supposed to be flown on an axis (think display line)- hence the importance of picking a line feature and sticking to it so is this not a fudge on the lines of an axial roll being flown with the pitch up a bit - whack in lots of aileron -stop the roll when level again technique that I've seen (been subjected to) which is horribly crude.
From which, note the technique used in the axial rolls early on in the superb Russkie video esp the pitch attitude when inverted, several degrees above the horizon. Watch it again but with your eyes on his stick-hand and see the pitch inputs that go into that maneuvre too, that ain't no aileron roll which will inevitably have a slightly sinusoidal horizontal flight-path even in a FJ. I bet his was straight as a ruler. Can any FJ driver tell us if top/bottom rudder input would be used too, or was the roll-rate too fast to need it?
Sithfighter. Aerobatics in cloud? Fooling about with a can of soda while flying aeros? Holy crap, and you post that here?
Not impressed.
I'm curious about the technique that commences the "BR" from level or nearly level flight. That must surely result in the roll itself being flown on an axis about 45' to the original line of flight and thus with a zig-zag ground track and the entry and exit tracks substantially offset. Goofing around apart, are aerobatic maneuvres not supposed to be flown on an axis (think display line)- hence the importance of picking a line feature and sticking to it so is this not a fudge on the lines of an axial roll being flown with the pitch up a bit - whack in lots of aileron -stop the roll when level again technique that I've seen (been subjected to) which is horribly crude.
From which, note the technique used in the axial rolls early on in the superb Russkie video esp the pitch attitude when inverted, several degrees above the horizon. Watch it again but with your eyes on his stick-hand and see the pitch inputs that go into that maneuvre too, that ain't no aileron roll which will inevitably have a slightly sinusoidal horizontal flight-path even in a FJ. I bet his was straight as a ruler. Can any FJ driver tell us if top/bottom rudder input would be used too, or was the roll-rate too fast to need it?
Sithfighter. Aerobatics in cloud? Fooling about with a can of soda while flying aeros? Holy crap, and you post that here?
Not impressed.
Last edited by Agaricus bisporus; 10th Jan 2011 at 13:31.
A-B, I`ll agree the Transall BR is not a `true` or accurate figure,and if you observed along the axis it would be rather egg-shaped,as most loops are due to the speed and G being different at the bottom and top...unless you have a good power/weight ratio,and minimise speed loss.Also it depends on whether you are displaying,or doing competion,as to how the figure will look to observers.
Sobolev actually rolls inverted after t/o and then pushes up in an inverted climb.Look for the other cockpit videos,ie looking backwards...
Sobolev actually rolls inverted after t/o and then pushes up in an inverted climb.Look for the other cockpit videos,ie looking backwards...
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One understands that the secret of a well executed barrel roll is to ensure that one gets the nose high enough to start with...
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One understands that the secret of a well executed barrel roll is to ensure that one gets the nose high enough to start with...
and also keep the nose straigh in the roll using rudder! some extra rudder is also helpful to increase rollrate.
Last edited by Lightning Mate; 10th Jan 2011 at 19:38.