Simviation Forums

Posted: **Sun Oct 26, 2003 4:41 am**

Can someone explain to me how to do a proper barrel roll as opposed to just an aileron roll?

Posted: **Sun Oct 26, 2003 9:15 pm**

The Barrel Roll is a not competition maneuver, as far as aerobatics is concerned. It was used mainly as an evasive/defensive maneuver in combat, particularly WWII. The goal is to force the attacker to overshoot the target. The idea is to shorten the distance a pilot covers in a straight line by adding lateral movement (the distance between the pilot and the attacker). Not so much to slow the plane down, which also works, but sacrificing too much airspeed or altitude for that matter in a dogfight can mean disaster. Also the complexity of the maneuver serves to defeat the guns resolution, at least for a short time until the attacker can correct.

The barrel roll is a combination between a loop and a roll. You basically complete one loop and one roll at the same time. Externally it looks much like a corkscrew lying on a table. While still not a maneuver used in aerobatic competition, it still requires a fair amount of skill to perform well.

In a barrel roll the accelerometer will always (or should) indicate positive G forces, usually between +0.5 and 3.0 G's.

as far as conrol inputs, you're basically pulling up, and banking, at the same time. In a snap-roll the center of rotation is the airplanes longitudinal(nose-to-tail )axis. Basically you roll hard with aileron, and maintain constant altitude with pitch.
With a barrel roll, you pull back on the stick/yoke and "slowly" roll the aircraft. As far as center of rotation, imagine the aircraft's lateral axis(wing tip-to wing tip). The wing moves sideways, curves upwards, becomes inverted and then falls back down through 360degrees of rotation, as opposed to spinning about the center(the fuselage).

Posted: **Mon Oct 27, 2003 2:19 am**

Ottol is right, what you need to do for a barrell roll is turn the aircraft into a 30-45' banked turn whilst pulling back gently on the stick, then snap the stick the other way, and hey presto barrell rolls

Ozzy

Posted: **Mon Oct 27, 2003 2:14 pm**

Aileron roll is about a point while maintaining altitude. Barrel roll displaces the aircraft from the original flight path. No single definition as it is not a recognized aerobatics manuver. Here is what I remember basic training T-28:
30 degrees of turn, 45 degrees of bank, 20 degrees N up; 45 turn, 90 degrees B, 30 degrees N up; 90 turn, inverted, nose at the horizon and repeat on bottom half of manuver.
Tactically, any roll and pull to displace from the bogey is called a barrel roll.

Posted: **Thu Oct 30, 2003 9:10 am**

Huh, trust me to leave el flight manual bible in the car...

I'll try and find the way the AP's tell you later (the way you're taught by the boy's in blue...)

Charlie

Posted: **Thu Oct 30, 2003 9:40 am**

Basically an aileron roll is done with ailerons, using elevator & rudder as necessary to keep the nose on the horizon. The aircraft will rotate directly around its own longitudinal axis. Most conventional aircraft are not capable of doing this properly or without losing altitude.

The barrel roll is quite different & controlled with rudder & elevator. Starting from straight & level flight, dive to reach the appropriate speed, then use up elevator with right or left rudder depending on the direction you wish to rotate. It's perfectly possible to do it without using ailerons at all as any R/C modeller with a rudder/elevator only model will confirm. This is a positive G manoeuvre like a loop. The path would look more like a corkscrew. If it's done properly you would not need to be strapped in. I've seen a demo film of the legendary Bob Hoover pouring a drink into a glass while doing a barrel roll without spilling a drop.

Posted: **Thu Oct 30, 2003 11:01 am**

Ok, the first diagram is what I thought was an aileron roll:

The second is what I thought was a barrel roll:

I thought a barrel roll was when the aircraft spun around a certain point. It seems like a good defensive manuever and I would love to learn the second one. The first is simple enough...

Posted: **Thu Oct 30, 2003 11:06 am**

Basically correct. Imagine a corkscrew in the sky. It should be easy enough. I just tried it in the FS2002 default Corsair which barrel-rolls beautifully without using ailerons at all.

PS.

This is what Ozzy was talking about:

The Barrel Roll is a defensive manuever. It is a more complex manuever in that one needs to have a very good foundation in the basics, particularly the yoyo, before you can master it. The Barrel Roll is very similar to the lag roll, but it is defensive in nature. Hence it will be done with greater urgency.
The barrel roll is defensive because its goal is to force the overshoot of an attacker who is closing fast. The idea is not so much to slow your plane down in airspeed, but to shorten the distance you cover in a straight line by adding lateral movement.

Think of it this way. An attacker is closing on your six from altitude. He is traveling from point A (Your six o'clock position) to point B (a position leading your flight path at 12 o'clock). By pushing your flight path to the side in a barrel-shaped circle, you lengthen the time it takes you to travel to point B while your attacker is already closing upon point B with great speed as it is. Also the complexity of the movements is able to defeat a guns resolution in the short term.

Execute the Barrel Roll by:
To begin a barrel roll roll 45 degrees right or left and begin a shallow climb. This will create the lateral movement you'll need to begin the roll. Many make the mistake of excluding this first step and they only perform a corkscrew which is easy to gun down. You need this first step to the side to creat a larger, barrel shaped, circle.

The next step is to roll back the opposite direction 90 degrees and pull again. So if you rolled 45 to the right and pulled up into the start of a yoyo, you then roll 90 degrees (45 until you are level, and 45 more to get set for a left yoyo) and pull (just like a yoyo) in the opposite direction. You will not need to be anywhere near a stall as you want to conserve energy for a kill (Step 4 below). If you did Step 1 correctly you won't have to work that hard at this.

Then you may watch for the overshoot. The attacker should shoot by like a seed being squeezed out of a grape! To begin with you will move him from your dead six view to your six high view and finally to your straight up view. Once he is in the straight up view, you have them. This is also your lift vector, and any time a plane gets in front of that you are moving over to the offensive. Rotate around your enemy simply by using the straight up view. Rotate so that you are rolling toward his flight path.

When he moves out of the up view to a more forward view, shoot the fool.

It's apparently a variation used in combat. I described the classic barrel roll. I'm no combat pilot & I've never done it this way.

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