What's the secret to good constant rate turns?

[copperkiid]

I'm working on forward and backwards flight. But I tend to slip my turns and they are inconsistent and a little sloppy. What is the stick input sequence for a good constant rate turn? For example, forward flight, turns...aileron, rudder then back elevator?

Are the stick inputs the same for turns in backwards flight?

Thanks.

[ArchmageAU]

Originally Posted by copperkiid

I'm working on forward and backwards flight. But I tend to slip my turns and they are inconsistent and a little sloppy. What is the stick input sequence for a good constant rate turn? For example, forward flight, turns...aileron, rudder then back elevator?

Are the stick inputs the same for turns in backwards flight?

Thanks.

Keeping the boom level with the ground and lots of practice.

You must steer the tail all the way through the turn (no just bank and yank).

- Forward turns are coordinated, (rudder and aileron same direction).
- Backward turns are un-cordinated (rudder and aileron opposite directions).

Take a look at Lesson 6 and 7 in From tail-in to all 8s and funnels in 6 months. Lots of info on turns, forward and backward.

[macdad]

I am still learning, and my technique is not good. However, I am noticing that I keep the rudder fairly constant like ArchmageAU says. I am also noticing that I used to give constant cyclic input. As I get better, it is more like micro adjustments on cyclic unless I am really ripping. I don't know if anyone has this experience.

[Mateyhv]

You are not he right path, there is always constant cyclic input in turns as the heli is unstable, so thats how you make it do what looks as a smooth path maintaining the same altitude. The rudder is much more constant than cyclic.

[Sirolf]

Follow the lesson as mentioned.
There is no fixed stick position or stick movement as to how to perform a certain move or transition. It also varies from pilot to pilot and heli setup.

Pratice..pratice..practice and you'll start doing it without even thinking

[MrHoverLover]

Focusing on keeping the tail level and the aileron wiggle Arch mentions has helped my turns improve. It's quite a balancing act but when you get it right it looks so sweet!

[KevinPJF]

I'm subscribing to this thread. I have been working the slow piro hovers for a while now (inconsistently until the last few weeks), but tried a circuit with the 450X and crashed it. That has me working on circles during my play time. I want to get all the input I can.

[Steve Graham]

FFF circuits are typically the first exposure one has to what I call steady stick maneuvers. Circuits, funnels, hurricanes etc have in common sticks that move very little throughout the maneuver once it is established. Because a circuit involves acceleration due to it being a curving flight path you will hold a constant input on elevator and rudder, still the sticks remain fixed for the most part as you fly through the circuit. What little movement the sticks experience will be minor adjustments to compensate for wind effects and turbulence to maintain the shape of the circuit. This is especially true with our FBL machines that lock the bank angle, pitch and heading unless we displace the controls from neutral.

For the OP, just to be clear the difference between a slipped and a skidded turn depends on the amount of rudder applied. Assuming the goal is flight that keeps the longitudinal axis, the tail boom, in line with the flight path you must use the proper amount of rudder. In a symmetrical circuit with a constant radius and assuming no wind this will be a constant fixed rudder input that keeps the tail in line behind the nose. Too much rudder drives you into a skid with the tail moving towards the outside of the turn. Too little rudder allows the tail to lag and fall to the inside of the turn. Many people struggle with nailing the right amount of rudder necessary for a coordinated turn that by definition is neither slipped or skidded. Most often IME they see that the model is either slipping or skidding at a fairly constant rate but fail to make the necessary changes to bring the tail inline. When this is the case they are holding the correct amount of rudder but they will momentarily need to either increase or decrease rudder input until the tail lines up with the flight path then go back to the rudder input they were previously holding. This takes discipline and practice to get right and a lot of people just sort of fly around with the tail always slightly askew. Fine if that was actually a goal you had in mind but more often than not it's just a sign of sloppy flying.

As far as a sequence of inputs goes it largely depends on the nature of the turn you're shooting for. A coordinated turn entered smoothly requires the simultaneous and smooth application of rudder as soon as the model begins to bank because the moment the "wings" leave level you should start to see the heading change. OTOH an aggressive aerobatic turn where the model is rolled rapidly with aileron to a fairly steep bank angle before pulling elevator won't see a need for rudder until the pull happens. A "pedal turn" where the rudder is used aggressively to skid the tail rapidly through a direction change is fun but by definition not a coordinated turn.

[LN400]

What I found: One deceptively tricky thing is to eye out the path beforehand without taking your eyes away from the heli. It is hard but doable, it only takes practice and slow flight to start with. Decide where you need the mast/disc to move to track that predetermined path. It's a lot harder than it sounds. I can be off by 1-2 meters at any given point of the circle and that's by going slow. Still, plugging away at it, don't ease up on your own requirements for what a good circle should look like.

As for tail: As much as it takes to keep whatever side of the fuse you want leading, to lead into the circle. Not really the answer you'd hope for maybe but that's how it is, I found: You need to play jazz with all the controls all the time to have the heli track the path and to have the correct side lead.

Start slow, like rrrreeeeaaal slow, like headhurtingly boring slow, and take it from there.

Just what I found so only take it for just that.

[Steve Graham]

I think you're getting into what we sometimes call visualization. Seeing the maneuver in your mind's eye before you do it.

In precision aerobatics with planks we sometimes use the term "see the exit" or "see the points" What this means, to me anyway is that we should have a very clear idea of how the model should look in order to nail wings level on the exit of a roll for example or the stops in a point roll. With practice and focus it really does help to hit your marks.

There are all sorts of points or marks in aerobatics that we can use as reference for executing and judging the precision with which the maneuver is performed. Here's just a few others. The exact moment the machine comes to a stop at the top of an upline for the initiation of the pivot in a hammerhead. The apex of a loop for a roll or pirouette. The exact midpoint of a line for executing the same such as in a cuban eight. The radius of a circuit or looping segment that should remain fixed. The angle of a line be it horizontal, vertical or at some other angle like 45 degrees. Symmetry and timing in drawing these lines, radii, rolls, piros etc are all at the heart of precision flight.

[ckankel]

Coordinated constant radius turns are something I’m trying to understand better right now. I’ve been working on circles and circuits in different orientations for the last few months. After learning to keep the tail level, forward upright turns are fairly intuitive for me and I make corrections in all axis simultaneously. However, in other orientations I’m still flying consciously instead of intuitively so I tend to correct one axis at a time. This has made me realize how little I know about the actual mechanics of a turn.

I’ve watched a lot of videos and read many threads. Many will tell you what to do but not why. I’m not talking about which stick goes in what direction but the interaction of bank, elevator, rudder, and collective. For example, one thing I’ve figured out is an effect of elevator in a skid or slip. Assuming a forward upright level turn, if you are in a skid (nose low and inside the arc of the circle) and increase back elevator it will reduce the bank angle because you’re pulling the nose out of the circle. If you add more rudder while doing so (maintaining the skid) it will eventually level off and climb out of the turn. If you don’t add rudder it will enter a slip (nose high and outside the arc of the circle). Increasing back elevator in a slip will increase bank angle because you’re pulling the nose into the circle and the heli will fall into the turn. Of course, if you add just the right amount of rudder you will have a coordinated turn (nose level and on the arc of the circle). But how does increasing elevator and compensating with increased rudder to maintain a coordinated turn (with no aileron or collective change) affect the turn? Also, I’ve read that increasing collective will increase the speed of the heli thru the turn. How does that work? What are other effects of collective changes in a turn?

I suppose there are many permutations of these types of questions. I thought a discussion of the mechanics of a turn might be interesting and enlightening.

[ArchmageAU]

Originally Posted by ckankel

Coordinated constant radius turns are something I’m trying to understand better right now..... This has made me realize how little I know about the actual mechanics of a turn.

I’ve watched a lot of videos and read many threads. Many will tell you what to do but not why. ...

I suppose there are many permutations of these types of questions. I thought a discussion of the mechanics of a turn might be interesting and enlightening.

I'll have a stab at the why.

Imagine a flat turn (like in a car). Rudder only required (lots of side drag). This turn requires no aileron or elevator. (yaw axis turn)

Then think of a jet wanting to do a sharp turn. The process is often referred to as bank and yank. Going onto a knife edge does alter the jets linear trajectory. It's the back elevator when on the knife edge that turns it (elevator acts as rudder because the axes have rotated {the plural of axis is axes}). This type of turn uses no aileron or rudder once knife edge established. (tilt axis turn)

Lets say you have a 45 degree angle (halfway between knife edge and flat). To do the turn you will need some of each (rudder and elevator) to turn. Both your yaw and tilt axes need to make the turn. The roll axis is not involved in the turn (just in making the initial angle).

The banked turn is MUCH more comfortable for the occupants of the vehicle. This is because the turn is a side acceleration. When this side acceleration is combined with the downward acceleration of gravity, being on a matching bank angle make the force feel always downwards.

[Steve Graham]

ckankel,

What you're really asking for is a primer on the physics of turning flight of which much has been written far better than I can elucidate here with a simple answer. Myself and others have tried in the past, here https://www.helifreak.com/showthread.php?t=573660 here https://www.helifreak.com/showthread.php?t=568820 and here https://www.helifreak.com/showthread.php?t=478585 for example.


The FAA's Helicopter Flying handbook chapter 2 http://www.faa.gov/regulations_polic...a/hfh_ch02.pdf Does a good basic job of explaining things in laymans terms so the topic is fairly easy to understand.

If I could offer a key element to level turning flight its that you understand the fact that it is ACCELERATED flight meaning the aircraft is not traveling in a straight line and therefore experiencing g forces greater than 1. In straight and level flight the machine and it's occupants experience 1G and that is the lift required of the rotor disc to overcome gravity. In a 60 degree level turn the heli will experience and be required to support 2G's. This is the combined effort necessary to support the "normal" 1G of gravitational pull plus the new 1G of centrifugal force generated by a 60 degree bank. This "effort" must come in the form of power lest airspeed and or altitude be sacrificed to make up the deficit.

Don't confuse bank angle with turn radius or rate of turn.

Turn radius is the size of the circuits flight path. With the bank held constant, ie constant G loading, the turn radius will vary as the square of the airspeed increase so turn radius goes up dramatically with increased airspeed. Useless fact alert: In 1999 the Air Force retired the SR-71 and delivered it to the Smithsonian museum at Dulles but not before setting one last record. It flew from coast to coast in 1 hour and 8 minutes at an average speed of 2124 mph. At that speed in a 25 degree level turn the aircraft's turn radius would be roughly 123 miles


Rate of turn is how many degrees per second the heading must change to keep the tail in line with the flight path sometimes called angular velocity. The rate of turn is inversely proportional to the airspeed at a fixed bank angle. This is why a slow speed small radius circuit actually requires a much higher rudder rate than a very high speed very large circuit that takes several times longer to complete.

You don't need a masters in physics to get this stuff but if you want to fully understand the answers to the questions you're asking you'll have to spend a fair amount of time studying the subject. This knowledge will arm you to not only apply the proper controls at the proper time but know why you're doing it.

[ckankel]

Thanks for the replies Arch and Steve. I have read through the FAA book before which was helpful. What I'm looking for is more positive control of the heli in a turn so I can maintain consistent speed, altitude and a more circular circle . Right now I feel like I'm guessing my way through it and I'm reacting to rather than controlling the heli. I think understanding the dynamics of a turn would be helpful and those links look like a good starting place.

[Not_Here]

I'm currently working diligently through Arch's All Eights....

I noticed a huge improvement in my ability to do slow controlled turns of any diameter banked or not, I can say it was a direct result of practicing ( to the letter as instructed) the piro-hover upright and inverted CCW and CW exercises. The confidence level has improved greatly from those exercises. I no longer feel anxious in those orientations that I felt unsure of before. It took me a couple weeks of three or four sessions a day on the sim... It was work. It was totally worth it

.