Barrel Roll
 

Could somebody please explain how to do this maneuver ??

Thanks in advance.

Barrel Roll
 

Very basic barrel roll: pitch up slightly, hold the small elevator input and add ailerons to roll the model. The plane will then corkscrew around, kind of like flying around the inside of the barrel, where you enter one end and fly out the other. The model will not exit on the same heading as the entry.

If you've ever seen the Blue Angels or Thunderbirds do their formation rolls, you'll see that they are all nicely-performed barrel rolls.

Barrel Roll
 

I use a bit of rudder. I do like a snap, just with about 1/4 to 1/2 the input.

Barrel Roll
 

Barrel Roll
 

What would the difference be between a snap and a barrell roll?

Barrel Roll
 

A snap is done with a stalled wing.

Barrel Roll
 

But do they look the same?

Barrel Roll
 

A traditional barrel roll has a large graceful radius a snap is usually a tight, quick auto rotation with a defined pitch break.

Now at this years Nats the FAI guys were doing these blindingly fast "snaps " with a questionable break. It will be interesting to see if this trend continues or if some judges get some guts and start giving some zeros.

Barrel Roll
 

Cool!! Thanks!

:)

Barrel Roll
 

A snap requires that the inner wing be stalled. The plane rotates around an imaginary extension of the flying line. The nose usually stays where it was in the flying line. A barrel roll requires no stall to take place. The plane still rotates aroung the same line, but does it at a much greater distance. The entire plane moves away from the flying line. From the front or rear the manuver looks like a loop with the plane going sideways.

Re: Barrel Roll
 

A barrel roll is done with elevator, aileron and rudder. it's normally coordinated and symmetric flight, 1 g maneouver. view from the side, it looks like a roll, but not on a straight line, with a quite big 'hump' in the middle, view from the front, or back, it looks like a loop.

The plane climb and start like a normal coordinated turn, at the top of the manoeuver, the plane should be inverted and flying on a 90 degres course in regards to the course it had entering the maneuver. I like doing it with small inputs and large, I think it's very smooth and nice, not stressing the airframe at all. Contrarly to what some said, the plane should finsih the manoeuver straight and level, on the same course and altitude it started.

I think the most famous barrel rolll ever done was made by tex johnson ( if I remember the name well) during one of the demo flight of the Boieng 707 over Seattle.

Bernard

Barrel Roll
 

Acually, there are several versions of the maneuver known as the "Barrel Roll".

One version, sometimes called the "Civilian" version, has the plane pull up, hold elevator while adding ailerons, and the exit heading is 90 degrees from the entry heading.

There's the "Navy" version, which has the plane follow a spiral path through the air, like the path of a stretched out spring. The exit heading is the same as the entry heading, but displaced to the side on a parallel track.

A third version, sometimes called the "Air Corps" or "Air Force" version has the airplane rolling about a point somewhere outboard of the wingtip. The entry and exit heading are the same, and the exit track would be an extension of the entry track.

The "Civilian" version is the easiest, but looks the worst.

Barrel Roll
 

I would say Bernie G got it right. That is how I did it in an AT-6. 90 degree course change during manuever and finish on the original heading.

Brian
KB1DTB

Barrel Roll
 

Barrel Roll
 

Sorry, i clicked too fast.

Well, I don't care much about versions and sub-versions. What I described is the original "Tonneau Barrique", as done and described by World war one french aces, then translated word for word in english. If you refer to the first US writings about aerobatics, they use french words for everything, and that's because they learned first from there.... What DEFINE a barrel roll, is a ONE G figure. I doubt anything different that what I described could be done at a constant ONE G !

One G means that, even while inverted, you can stand up in the plane and not fall. A NOT coordinated roll would have as result that you would fall on the roof !

Bernard

Barrel Roll
 

Bax,
That sounds trick. How do you do the AIr Force version? Roll point outside the wingtip? I'll have to bone up on rolls this W/E.
Rick

Barrel Roll
 

RickP

Well, at least that's how it was described to me. Actually, I think that would be rather difficult to do. Very likely, it would probably be more like the "Navy" version, but with a larger radius on the pullup

Bernie was right on about the 1G maneuver.

bax

Barrel Roll
 

Wow... And here I thought just throwing the aileron full right or full left was good enough. Looks like got a lot to practice!

:)

Barrel Roll
 

I'll have to throw my 2 cents in since I taught barrel rolls as an Air Force instructor pilot in T-37s many years ago.

The maneuver is a spiral in the sky. The differences are in the instruction. As for it being a 1g maneuver, as an engineer, I question that. If you pull up, you are pulling more than 1g. Maybe not much more, but slightly more. The tighter and faster the roll, the more gs you'll pull.

As for the "spot on the canopy" vs. other methods, they result in the same maneuver when viewed from outside the airplane. I always found that students had a harder time learning the "spot on the canopy" technique so I tended to teach the maneuver using section lines or roads.

You picked out a road and dived on it to gain airspeed. Then you turned off to one side 30 degrees (or whatever amount you wanted). You started a gentle, rolling pull-up, continuing over to inverted. You watched the road and timed the roll so when you were on the horizon inverted you were 30 degrees off to the opposite side of the road. You continued the roll and gentle pull to place the airplane upright back over your original 30 degree line.

If the student had great difficulty, I used a crossroads and a 45 degree turn off. I had him line up between the 90 deg. angle formed by 2 crossing roads, then turn off to one road. He would fly inverted to the other road, then back to the original one. This gave a huge barrel roll, but it was easier for the slower students to visualize.

What you are seeing with the arco teams is a berreled out version of an aileron roll. In ful scale planes (competition acro planes excepted) you keep 1 g to stay in the seat so aileron rolls tend to look slightly barrel. In a formation roll, which I have done in several airplanes, the leader keeps slightly over 1 g so the wing men have an easier time staying in position. Otherwise, the inboard wing man would be using negative gs.

We generally don't do barrel rolls in RC since they, of necessity, cover 3 dimensions and are hard to judge. Viewed from the side, how far out was the plane in inverted? Hard to see.

Hope this helps.

Re: Barrel Roll
 

Ed,

Agree, it depends of the roll rate and can be slightly more than 1, but never LESS, wich is always the case in any "other" roll.

Bernard