Dutch Rolls

[somorris]

Hi guys.

On another forum board, a discussion has been underway about Dutch Rolls. I am not sure I am getting the correct answer so am coming to the experts.

I was taught to do Dutch rolls by holding the nose on a point, then banking left and right with no hesitation and keeping the nose on a point the whole time. The banks can be 45 or 60 degrees each way (or more or less depending on preference, I guess). The argument is whether or not the ball will stay centered during Dutch rolls done correctly. I went out yesterday (C-150) and tried it after I was told the ball should max out on each side of the cage by an aerobatic pilot that should know. My ball stayed in the center (more or less, since it was difficult to stay totally coordinated with the differenct rudder pressures required and I had to keep an eye out for traffic). Either I am doing something wrong, or the other pilot is telling me wrong, or we are not totally coordinated with each other. Can you guys help out with my understanding?

Note that I am not an aerobatic pilot, just an enthusiast that has had a very few hours in a Super Decathlon doing aileron rolls, a few loops, and falling leaf stalls. I want to do more, but as always, money is a factor.

Thanks for your help!

Stacey

[Bill Greenwood]

Although I have a low level acro card for rolls, I have never done competitive acro, so someone may differ. But it seems to me that this is not a coordinated manuever, that the ball will move around. The object is to keep the nose straight in the center not the ball.

[WLIU]

Hello,

There are two ways to fly this. If you apply coordinated rudder and aileron, I think that I recall that you can keep the ball in the center as you go back and forth from bank to bank.

What a aerobatic pilot is more likely to do is roll from knife edge to knife edge, holding altitude and heading. That requires opposite rudder to keep the nose up on the point. I will also note that many aerobatic airplanes have no ball to look at. A standard ball installation does not work inverted and when upright, a competent pilot should be able to feel the yaw without the use of a ball.

So your friend may not be flying the exact same maneuver you are flying. From your post I believe that you are flying a "Dutch Roll".

As an aside, is an "acro card for rolls" a warbird thing? When I let my ICAS membership expire you got an airshow competency card that was good down to a specified altitude through an ACE that had to be renewed each year and allowed you to fly any program that you wanted. The FAA stopped doing competency evaluations and handed it off to ICAS. If you did not renew each year it became a useless piece of paper.

Best of luck,

Wes
Pitts N78PS

[Docrob]

Somorris: You are doing the maneuver exactly right. The purpose of Dutch rolls (sometimes call Coordination Exercise) is to teach a pilot to apply exactly the correct amount of rudder to compensate for adverse yaw caused by the ailerons when rolling into or out of a turn. If your coordination is good, you should be able to roll from level flight to 30 or 40 degrees of bank in one direction, reverse the roll to roll 30 - 40 degrees in the other direction, then reverse again back to level flight, keeping the nose on a point on the horizon, and keeping the ball in the middle throughout. The application of this is to learn to use the same control pressures to roll into a turn, neutralize rudder and aileron when reaching the desired bank angle, and adding a little back pressure to make a turn. When you reach the desired heading, apply top aileron and rudder to roll back to level flight. Rolling into a turn (every turn you make,) the heading should not change until the bank is established, and completing turn, the nose should stop on the horizon at the desired heading while the wings are rolling level (and the ball remains stationary through the entire maneuver.) Suggestion: Do two or three cycles each way, and then fly straight and level for a few seconds. If the nose (or the skid ball) starts moving around, it becomes increasingly hard to "catch up." Just stop and start over. Get good at this, and you'll amaze your friends at how good all your flying gets.

Dr. Rob
ATP, CFI, DPE (and a bunch more stuff)

P. S. Since the FAA, in its infinite wisdom, chose not to put this maneuver in the Practical Test Standards for any license or rating, it's not taught much any more. Most instructors just want to get the student through the checkride, so they don't throw in much in the way of extras. It was taught as a formal, testable maneuver, in the Army Aviation School in the 1960's.

[Bill Greenwood]

Wes, my acro card was first issued by the FAA about 1987. Since then I have had a civilian evaulator issue the remewals. It used to be Carl Schmeider. I will treasure my most recent one as it was issued by Howard Pardue, done in Breckenridge.

I think all cards have an alitude limit, mine began I think at 800 ft and is now 500 ft. I don't need to do any acro, rolls or otherwise, at 100 feet.

Mine specifies the plane and type maneuver. I don't have any interest in doing vertical acro at 500 ft.Mine is rolls only. I am sure that many of the airshow folks and particularly acro only type planes have an unlimited type card.

[RetroAcro]

Although I have a low level acro card for rolls, I have never done competitive acro, so someone may differ. But it seems to me that this is not a coordinated manuever, that the ball will move around. The object is to keep the nose straight in the center not the ball.

If your coordination is good, you should be able to roll from level flight to 30 or 40 degrees of bank in one direction, reverse the roll to roll 30 - 40 degrees in the other direction, then reverse again back to level flight, keeping the nose on a point on the horizon, and keeping the ball in the middle throughout.

OP, seems the confusion persists. :-)

[WLIU]

I think that "Docrob" covered the topic comprehensively. Keep doing what you are doing.

Very interesting that "my acro card was first issued by the FAA about 1987. Since then I have had a civilian evaulator issue the renewals." I have to guess that the warbird community has gotten their implementation of the program tweaked a little. That group tends to do more traditional maneuvers given that their equipment is harder to keep in front of a crowd and is actually less aerobatic capable. I hang with the unlimited acro crowd so I have not seen an airshow competency card with a maneuver restriction. A Pitts/Laser/Extra/Edge flight program typically involves snaps, avalanches, and maybe tumbles in addition to vanilla loops and rolls. So no point in putting a restriction on the card.

On the topic of acro in Cessna 150's, the wonderful Amelia Reid used to do a show in an A-150 that you would not believe. Used every bit of performance that the airplane could give.

Fly safe,

Wes
N78PS

[RetroAcro]

Wes, wing-wagging into the box is a dutch roll no? ...even if you only go to 45 degrees and not knife edge. Do this coordinated with the ball in the center and you will be off heading going into figure one, meaning the nose is going off heading (not on point during the process). This one requires opposite rudder to keep the nose on point, which makes the maneuver very uncoordinated.

[somorris]

Thanks guys, although I am still a little confused. I guess if you are flying competition, the wing wagging going into the box is an uncoordinated Dutch roll, although the original intent of a Dutch roll was a coordination exercise? The guy I was going back and forth with was an acro competitor, so I can at least now understand what he was getting at.

Thanks again!

[WLIU]

Well competition rolls are NOT coordinated and are NOT "dutch rolls". A competition roll uses lots of opposite rudder and puts you against the down side of the airplane when on knife edge. A ball would be all the way out to the side a lot of the time. The goal is to keep the CG of the airplane travelling in a straight line while the airplane rolls. Since the airplane does not lift well as it passes through the knife edge points you have to sneak the nose up at the start and use lots of top rudder at each knife edge point.

A box entry wing wag can be one of the most violent rolling figures that you do. I put the nose down 45 degrees and slam the stick over as hard as I physically can. I am rapidly loosing altitude and building speed and my goal is to hit the airframe red line speed at the moment that I complete my third roll to 45 and back. The throttle is all the way in so speed builds and altitude goes away fast so I use all of my strength on the stick so that I do not waste altitude.

Your Dutch Rolls are relatively calm.

Stop by an aerobatic contest this summer and check out the flying. Some of it is pretty violent precision in the airplane. Some is very gracefull. Its a great challenge.

Have fun,

Wes
N78PS