Aerobatic ATR
In a well executed barrel roll you will not be pulling much G - well within the design limits - even a Boeing 707 has been rolled before now!
The risk is if it's poorly executed and you end up pulling excessive G to recover.
There are countless stories of transport a/c being barrel rolled. Recall Neil Williams barrel rolling a Jetstream in cloud whilst the sales teams were down the back selling the a/c - nobody even knew he had done a roll!
Not condoning this sort of activity but its hogwash to say you pull a lot of G in a well executed barrel roll.
The risk is if it's poorly executed and you end up pulling excessive G to recover.
There are countless stories of transport a/c being barrel rolled. Recall Neil Williams barrel rolling a Jetstream in cloud whilst the sales teams were down the back selling the a/c - nobody even knew he had done a roll!
Not condoning this sort of activity but its hogwash to say you pull a lot of G in a well executed barrel roll.
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I may be a little thick this morning. A loop and a roll? I don't grok your "loop" part of the Barrel Roll.
http://www.iac.org/begin/figures.html#Barrel%20Rolls
Imagine a loop is a coil of wire. Get hold of the two ends of the coil and pull them out horizontally - you now have the path scribed by an aircraft doing a barrel roll - you can have a big barrel or a small one. Hence a barrell roll involves more pitching than rolling because it is by definition more of a looping maneuver than a rolling one.
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fireflybob
I see your point. However, if pulling the wire apart describes a loop, there is a syntax problem. Basically you are saying pitch combined with roll equals part loop, part roll. The coil represents "tight" loops, very "loose" rolls. Vice Versa. The Professor Eichorn calls a Barrel Roll a combination "between" a loop and a roll. I think what he meant to write was a "compromise" between a loop and a roll. Or a combination "of" a loop and roll. If one "blends into the next" (relative to "purity"), when is a loop just a loop? Said another way, when does a cucumber become a pickle? Or are they always some of both? Also, Looking at your "horizontal" corkscrew you would claim a series of Barrel Rolls had been performed. Looking at the same horizontal corkscrew end on, you would insist it was a series of Loops.
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Classic 707 Roll
So where does the classic 707 roll fit?
http://www.youtube.com/watch?v=WJ546BEps-M
Tex Johnson said he would do a "roll to impress the people" and called it a chandelle. I don't think this is the current definition of chandelle. I gather it does meet the barrel roll definition.
http://www.youtube.com/watch?v=WJ546BEps-M
Tex Johnson said he would do a "roll to impress the people" and called it a chandelle. I don't think this is the current definition of chandelle. I gather it does meet the barrel roll definition.
212Man ---it is a 1 g maneuver provided that while you're rolling in at a rate in proportion to the rate at which you are falling back to level height
Firefly, you are correct - a well flown barrell roll does not result in much g, however, it is an urban myth to suggest it is a 1 g manouevre, and generally perpertrated by people who have probably never exceeded 20 degrees of pitch or 45 degrees of bank in their lives!
Last edited by 212man; 15th May 2008 at 12:54.
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Barrel rolls
A Barrel roll is an extrememely dangerous manoeuvre,especially when performed by improperly trained Pilots.When I did my QFIs Course,the Instructor stated that more Pilots killed themselves in this way,because you end up with a highangle of attack with low airspeed and going through the inverted with a natural instinct to pull through,instead of waiting for the nose to drop through cof g and the resultant roll out.When achieved properly it is more of a screwed loop with continuous small amount of G,than a roll,commenced with a gentle divebelow the horizon,starting the roll to be fully inverted at the same amount above the horizon,easing off the G in the pull up,continuing the the roll,with a gentle pull and roll out.2g is ample to achieve this,and an aileron roll is capable of being achieved at only 1 g.Aileron Rolls can be flown by attaining the desired entry speed,a slight pull up and applying aileron,until the 360 is achieved.Thus verysmall G used.Only maintaing direction and altitude needs watching.Heavy handed pulling and pushing will only lose energy and look terrible from the ground.Having rolled several Airliners in the Sim,it is perfectly possible with a dive entry at at sensible speed(Vmo),and a gentle pull up to say 30 deg ,check the attitude slightly and gently put on aileron to the required diection,and then check the nose drop in the resultant roll out.Unfortunately most times I have seen this done ,the Aeroplane has tended to rather fall out of the sky in the roll out,because they have not given a gentle push as the last part of the roll occurs.The 707 Roll was an Aileron roll,and NOT a Barrel roll.The famous B52 Accident was an Aileron roll that was far too low and the resultant Nose drop had to be contained by a considerable pull out that never made it.Most rolling accidents could have been avoided if the addage"If in doubt ROLL OUT",is applied ,because most that go wrong end up with a "Pull Through",rather than check the nose attitude to below the horizon inverted ,let the ASI increase,and THEN roll out,accepting you have made a cock up,and LIVE to fly another day.With the natural reaction to think you can pull through,you must think off the Terra Firma below,and the resultant TREMENDOUS height loss you will suffer,and the necessary G force required to return to level flight,and the structural limits of the Aircraft,when pulling out from a high speed dive close to the ground-The A10 Accident in Paris,The Spitfire at Woodford, the Mosquito at Barton,and more recently the Hurricane at Shoreham,which flicked when a high G pull out occured.As far as 212Man is concerned,I would point out that I was a Display Pilot throughout the 70s and early 80s in both Piston and Jet Aircraft,and am only one of a few left from those times,plus did many successful aerobatic courses.
Last edited by FAStoat; 15th May 2008 at 14:13.
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The famous B52 Accident
Incidentally, from memory the Spitfire at Woodford was looping I believe, the Mossie a wingover which went awry when one engine lost power, and I'd suggest that the Hurricane may have stalled rather than flicked during a derry turn, in much the same manner as the Firefly at Duxford.
I think the Mustang replica at Barton, the P-38 at Duxford and the Invader at Biggin are examples of rolls going terribly wrong for whatever reason.
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FAStoat: Thanks for that. Very helpful for understanding rolls (barrel or otherwise), and the way it looks for the pilots performing them, versus what they need to do to perform them correctly. 
Shame about all of those wonderful aircraft that didn't quite make it, and the unfortunate consequences for the crews.
Shame about all of those wonderful aircraft that didn't quite make it, and the unfortunate consequences for the crews.
Surely the crux of this argument is whether one wants to return the aircraft to approximately the same altitude at which the manoeuvre was started. This requirement is clearly essential for a low-level display and the barrel-roll manoeuvre thus requires a quite aggressive initial pitch and near-completion of the rolling element before the downward acceleration builds-up - allowing almost full pitch authority to be available for recovering from the dive to S+L at the desired height.
Tex Johnson's 707 had plenty of altitude and he could afford to lose some. I suggest that he started with lots of speed and began the manoeuvre by pitching the aircraft into a climb - this initial pitch would have been greater than 1g, but within the limits of the airframe. As speed was traded for altitude he then applied a large rolling force using the ailerons. As the lift vector moved away from the vertical the aircraft weight would have caused it to begin to descend. With no pilot input this would have developed into a sub-1g "freefall". However, Tex used his remaining pitch authority and energy to apply a positive 1g - which he maintained as the aircraft rolled all the way round -with maybe a bit a rudder to keep the roll going as the airspeed fell. The aircraft was returned to S+L by easing off the pitch as the wings became level, but at a much at lower height than entry. Voila, a "1g roll" but not really a barrel roll because the aircraft only described about three-quarters of the path around the inside of the "barrel".
Tex Johnson's 707 had plenty of altitude and he could afford to lose some. I suggest that he started with lots of speed and began the manoeuvre by pitching the aircraft into a climb - this initial pitch would have been greater than 1g, but within the limits of the airframe. As speed was traded for altitude he then applied a large rolling force using the ailerons. As the lift vector moved away from the vertical the aircraft weight would have caused it to begin to descend. With no pilot input this would have developed into a sub-1g "freefall". However, Tex used his remaining pitch authority and energy to apply a positive 1g - which he maintained as the aircraft rolled all the way round -with maybe a bit a rudder to keep the roll going as the airspeed fell. The aircraft was returned to S+L by easing off the pitch as the wings became level, but at a much at lower height than entry. Voila, a "1g roll" but not really a barrel roll because the aircraft only described about three-quarters of the path around the inside of the "barrel".
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That is absolutely correct.the point I was trying to make,although the analogies were not all the same,was that Airliners do not have the control surfaces,or structural strength for such manouvres,and that even Aircraft that are built to withstand such forces,are sometimes lost because of Aircraft Departure,be it from Structural or Pilot failure.In most aerobatic courses,the first exercises,after having been shown that the Aircraft can Roll and Loop,should be recovery from various forms of Departure.You can achieve a considerable variation from cocking up a Barrel Roll,which will last forever in the memory banks of the Student!!
Barrel roll
A picture maybe worth a thousand words,but a simple `tool` may help...take the inside cardboard roll of a toilet/kitchen roll,and at the end of the `spiral`wrap draw a little aeroplane proceeding along the spiral,every 30,60,90 deg etc, to the other end,at least thru` 360 deg. In a simplistic way you can now see the flight path of the aircraft.In reality the `path` is a lot more `compressed`,but it serves its purpose.A wider tube is better,however they both illustrate several important points/differences,and similarities.
If you look at the barrel,at every 90deg point the wings should be-level at bottom, vertical on sides,and level at top(inverted).If you look down on the barrel the flight-path `track is offset(by the `thread`),from the centreline of the barrel, from perhaps 30-60 degrees depending on how ` tight`,or big` you decide to be.
In reality,if you have lots of speed, make it big, lower speed ,make it tight..
If one looks thru` the barrel at the horizon, a `golden rule` should apply,in fact for any roll; axis of the roll should be- Always above- seldom level- never below(the horizon)!(unless one is experienced ,comp.style).By tilting the `barrel` you can see how the picture will change,especially a downwards vector in the latter part of the roll.
Another point is that rate of roll and pitch should be matched; the roll is thru`360 deg,the pitch may be thru`+-30(60) deg for a `tight` roll,or+-60(120)deg for a big roll ,so these must be matched.Also speed varies throughout the roll,so the pitch/roll rates will as well ( unless you fly Typhoon/Su35/F16 etc)
Commencing a barrel roll,I always begin by rolling/diving to build speed say to left,and then rolling right,or vic.versa,but always looking at my 2o`clock for a roll right, or 10 o`clock to left,for axis alignment.The `ball` should remain in the middle, throughout,and one can use about 2.5G with lots of speed. That will stop the coffee spilling..
KEY POINT;at the top ,inverted, if the nose is not above the horizon,wings-level,ROLL-OUT;do not try to salvage it.
That`s about a thousand words;next time you`re in the `bog` do something constructive !!
If you look at the barrel,at every 90deg point the wings should be-level at bottom, vertical on sides,and level at top(inverted).If you look down on the barrel the flight-path `track is offset(by the `thread`),from the centreline of the barrel, from perhaps 30-60 degrees depending on how ` tight`,or big` you decide to be.
In reality,if you have lots of speed, make it big, lower speed ,make it tight..
If one looks thru` the barrel at the horizon, a `golden rule` should apply,in fact for any roll; axis of the roll should be- Always above- seldom level- never below(the horizon)!(unless one is experienced ,comp.style).By tilting the `barrel` you can see how the picture will change,especially a downwards vector in the latter part of the roll.
Another point is that rate of roll and pitch should be matched; the roll is thru`360 deg,the pitch may be thru`+-30(60) deg for a `tight` roll,or+-60(120)deg for a big roll ,so these must be matched.Also speed varies throughout the roll,so the pitch/roll rates will as well ( unless you fly Typhoon/Su35/F16 etc)
Commencing a barrel roll,I always begin by rolling/diving to build speed say to left,and then rolling right,or vic.versa,but always looking at my 2o`clock for a roll right, or 10 o`clock to left,for axis alignment.The `ball` should remain in the middle, throughout,and one can use about 2.5G with lots of speed. That will stop the coffee spilling..
KEY POINT;at the top ,inverted, if the nose is not above the horizon,wings-level,ROLL-OUT;do not try to salvage it.
That`s about a thousand words;next time you`re in the `bog` do something constructive !!
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Well i stick to what i suggested in post 4 and that it was an aileron roll due to the fact it was entered from runway heading not from an oblique angle as would would associated with a barrel roll, and most drivers that i have ever worked with still think those pedals on the floor are foot rests with little paddles on the top of them to make the goodyears stop turning when they cocked up the landing and desperatley want the self loading freight to headbutt the seat in front....... or they wanna be an Eddie Stobart trucker when they get to the gate and love the feel of the NLG oleo bounce....lol - and i still think we should move it again to Flight Test as we would then get the likes of his Masterful Farley and co giving us humbled wannabe ETPS skygods a damn good lesson in aero dye namics........ 
You can perform a barrel-roll without first offsetting by 45-degrees.
Pick a point off the wing-tip such as a cloud or a ground feature, then pitch-up as if for a loop - as the nose gets high, roll to bring the nose down though the point you picked to cross it with wings level and aircraft inverted. At this instant look across to the same wing-tip and pick another point, continue the rolling and pitch to bring the nose back to achieve wings level at this second point.
The difference to the diving left/right entry is that you will come out 45-degrees off-axis. Hence this technique has to be sequenced with other off-axis manoeuvres.
Pick a point off the wing-tip such as a cloud or a ground feature, then pitch-up as if for a loop - as the nose gets high, roll to bring the nose down though the point you picked to cross it with wings level and aircraft inverted. At this instant look across to the same wing-tip and pick another point, continue the rolling and pitch to bring the nose back to achieve wings level at this second point.
The difference to the diving left/right entry is that you will come out 45-degrees off-axis. Hence this technique has to be sequenced with other off-axis manoeuvres.
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Brian, as a keen and current aerobatic pilot i completely agree but my point is based on the photos of the ATR doing a beat up on runway heading, the rudder not moving much throughout the sequence, and the aileron deflection versus roll and yaw, it looks like a standard heavy metal aileron roll.....thats all but hey - who cares..!! not me it didnt crash, i know the serial number, and i aint gonna get in it no matter.... hoorar..... its friday and Pimms O'clock - last one to land rings the bell................................ your round...!
Couldn't get the clip to work, so couldn't actually see what he did.
However, in a twin or a jet he wouldn't need visible amounts of rudder because the aircraft wouldn't go out of balance as the airspeed changed.
However, in a twin or a jet he wouldn't need visible amounts of rudder because the aircraft wouldn't go out of balance as the airspeed changed.
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One summer of intense aerobatic training and activity many years ago, I ended up fixated on the idea of the "perfect" barrel roll. Concentrating on that manoevre again and again till I could ask a friend sitting in the second seat to close his eyes and tell me when we were upside down, he couldn't. Not saying that it is 1G all the way, but if done correctly even the entry and exit forces are light.
However having been through all of the potential variables of screw up while practicing and experimenting, in a strong aerobatic aircraft with large control surfaces, would I like to have a go with my crusader ? don't think so.
However having been through all of the potential variables of screw up while practicing and experimenting, in a strong aerobatic aircraft with large control surfaces, would I like to have a go with my crusader ? don't think so.
Hey 212 Man
ok the little pitch up required the aircraft is instantaneously loaded to slightly greater than 1g, but with some practice the roll will be contained in to 1g for the reasons I explained
I prefer to perfect my reverse Cuban eights or snaps
--
Mark1234
-I now get what is meant by 'barrel roll' it's just a falling roll---but it is not a competition maneuver anyhow---neither is an aileron roll---sometimes the terms are confused and used interchangeably.
Entry speed [180 mph or so]- stick back and into the corner-hard corresponding rudder-- hang on and take your pill
PA
So, can you explain how you are able to raise the nose above the horizon and climb, without pulling more than 1g?
I prefer to perfect my reverse Cuban eights or snaps
--Mark1234
-I now get what is meant by 'barrel roll' it's just a falling roll---but it is not a competition maneuver anyhow---neither is an aileron roll---sometimes the terms are confused and used interchangeably.
Entry speed [180 mph or so]- stick back and into the corner-hard corresponding rudder-- hang on and take your pill
PA
Last edited by Pugilistic Animus; 20th May 2008 at 01:27.
