Executing a 1G barrel roll?
 

So what is the procedure exactly? From what I gather one pitches about 20 degrees and descends at a certain rate, but I suspect that's wrong.

IIRC, in the T-38, one picked a point in the nose, turned off 45 degrees and began a 2G climb and roll that held the point in on place off the nose. Not 1G, but probably not possible in a -38. One wound up 45 degrees nose high and low.

GF

I think a barrel roll must be 1G or it is not one. Tex did a pretty good one in the 'X' 707. (:D)

My friend Keith says a BR in the Talon is frustrating, it wants so much to snap instead, and that is way more fun. BR, finesse. SR, cookie crumbler. especially at 720 dps.

bear

Bear, Tex Johnson did more of an aileron roll than a barrel roll.
YouTube - Boeing 707 roll by Test Pilot Tex Johnson
If you will observe, the aircraft in the video is on more of a ballistic trajectory during the maneuver.
From memory, the type of barrel roll you do depends a lot on airspeed. We used to do 90 off heading barrel rolls in the T-34 and other slow aircraft and 60 or 45 degree off heading barrel rolls in various tactical jets. By off heading, I mean how far you were off initial heading as the nose fell through the horizon inverted. Roll rate and g are not constant although g is always positive if done properly. Not a terribly difficult maneuver.

bearfoil,

What do you mean by cookie-crumbler?

To my way of thinking, you cannot do a barrel roll at 1g. Firstly, you have to pull the nose up to start it. That's more than 1g. Secondly, you have to pull more than 1g to get the nose back up to the horizon again after being inverted, unless you do a wiffodil and twinkle roll to wings-level at the end, but then you'd end up at a higher altitude than when you started.

It would be quite easy to do in a big jet at less than 2g provided you don't let the nose get too low after inverted and have to pull like a $%^&*@ to recover; start nose-high and keep the roll-rate up ie don't do it the way Tex did it. Start rolling with the nose well up.

Exactly. To get 1g while inverted, there's going to have to be some acceleration at the start of the manoevre if it is indeed going to be a barrel roll. If you do acheive inverted without pulling more than 1g, the nose is going to be very low and the will be some acceleration to recover.

galaxy flyer,

So you'd turn 45-degrees off heading, then pull up while rolling; or you while rolling you reached a maximum of 45-degrees off the original heading?

It isn't possible to do a 1 G anything in an aircraft (apart from parking it on the ramp!). When people talk about "1 G barrel rolls" they generally mean a balanced, positive G barrel roll - one in which you could place a glass of water on the glare shield, and have it stay there.

The barrel roll is a "twisted loop" in which the aircraft flies a corkscrew path through the air. If you are in flight, stooging around for your own enjoyment, you choose the axis of the manoeuvre off to one side, then (accelerate if you need to) and pull into the figure, introducing the roll after the initial pull. With this method, once you have recovered to level flight, you should be flying on the same heading - but the aircraft will be displaced to the left/right of the original track.

If you are flying the figure for a ground observer (which would be unusual), then you turn off you track in the opposite direction to the roll as you dive to accelerate - this keeps the axis of the figure aligned along your display line.

A 1G barrel roll would be impossible...at best you could expect 1G at the inverted stage and 2G at the completion of the roll but still nose down but recovering. The way I was taught was to turn off to say the right with turn overbanked to get the nose down. Then start the roll to the left but maintaining positive G by keeping back pressure on the stick. For the first half of the roll the nose would be above the horizon and for the second half it would be below the horizon. To avoid a steep nose down attitude at the end of the roll, you need to ensure that the nose comes high enough above the horizon in the first part of the roll. Mistakes are usually to not get the nose high enough before the roll passes the 90 degree of bank station. This will result in a steep nose down attitude as you come out of the roll with large loss of height...So next time get the nose higher :)

The slower you roll, the more difficult the manoeuvre, so leading a barrel roll as a formation aerobatics team leader is pretty hard to do well...If you roll too fast you will start shedding wingmen :rolleyes:

during my basic aerobatics course on a De Havilland Chipmunk, I was taught to pick a prominent feature on the horizon on either wingtip, i.e. 90deg of current heading, then lower the nose into a shollow dive to gain speed (possibly around 120mph), and then simulataneously pitch up and roll steadily until the "feature" previously selected appears directly on the nose as the aircraft passes thru inverted straight and level position, now without any extra rolling or pitching forces it was just a matter of allowing the manouvre to "complete itself".

Barrel Rolls
 

Mmmm... I remember some poor soul trying to teach me, and I now try to teach others. It is a very simple manoeuvre once you understand what you are trying to achieve. To get to that stage, safely, is far from easy, since you are having to co-ordinate 2 "rates" (roll and pitch). From the number of fatalities, frights and VNE exceedences I would therefore disagree with your statement :=

Agreed in the classic sense. Reviewing that video, firstly TJ never describes it as a Barrel Roll, and nor would I ;) It is potentially all flown at 1g - he's started rolling, and kept the 1g applied - end result is in the inverted position the nose is well below the horizon and rapidly falling further... so could well have all been done at 1g, but he would have needed somewhat more to arrest the rate of descent :D

Anyone trying to do Barrel Rolls, please do NB the 1 absolute safety gate - as the nose passes down through the horizon (pitch) the wings must be at or past the inverted position (roll)... if not then check forward, roll upright and try again this time with a higher roll rate / lower pitch rate - do not "pull thru'" :{

In teaching, I tend to get the student to pitch (only) until their feet are on the horizon, and only now slowly start the roll, while still keeping the pitch going. The common errors are to start rolling too soon / too quickly, and stop pitching up. Only when they have got a grasp of the relationship between roll and pitch do I add ground features / angles off etc.

NoD

A 1g barrel roll is impossible.

LM. (one time international aerobatic competition winner) ;)

OK Bloggs - now let's try a loop to the left:D

Maybe I have misunderstood some of the descriptions here, but it appears to me there is some variation in what exactly a barrel roll is.

This is how it was described to me by my RAF instructor, admittedly a long time ago, so it might have changed
Commence at A with wings level on the horizon, pulling up and rolling right to have 90 degrees of bank at B, inverted as we pass through the horizon at C, 90 degrees of bank at D, and recover back at A.

http://img.photobucket.com/albums/v712/crun9/broll.jpg

diagrams
 

I've seen some awful diagrams of the aircrafts supposed position during barrel rolls. Henry's isn't so bad but I don't think many underpowered trainers could start from "A" without falling out at the top.

I did a few in a Victa, completing the barrel shape regardless of where the a/c was this way or the other. Started with the nose on a feature, dived and turned to arrive at Henry's "A" with a bit of speed up, probably already at 90deg by C, falling to D at upright and pulling back to A to finish. Rough and self taught, but my instructor wouldn't sign my log book for barrel rolls because, "you can do them better than me." Mind you, he signed for everything else. :rolleyes:

Worth watching this

YouTube - Stopped engine aerobatics


about 2 mins in is a good demo. I imagine >1g ...

I love the sound effect of the tea being poured !!

BOAC,

Would that be with one or nine mate. :E

The only 'bent' nine-ship one I can recall was DD's arrival at Barton along the wrong canal, but by skilfully bending the loop he arrived on datum at the bottom without shedding one of the boys.:)

That's called skill mate. :)