Getting into a routine
Having taught us the basics of rolls, loops and autos, this month John Parker encourages us to knit them all together
It’s time to combine and modify the manoeuvres you’ve hopefully learnt from the previous articles in this series. We have gone through the roll and loop, before describing the standard approach to autorotation; I would also expect that you can now perform a nose-in hover, plus a complete stall turn from both directions.
In the case of the loop, which was the first to be covered, note that we can take this to the extreme by turning it into a backwards flip quite easily. As regards rolls, these can be tightened right up and turned into aileron flips. Finally, note that our standard-approach auto can be added to the end of a sequence. This is what I mean when I say we should now be putting our manoeuvres together, and taking them on a bit further.
Key to the performance of a back flip is the use of rear elevator, and the collective control – no, we don’t require aileron use at this point.
Our loop involved forward flight with a good amount of airspeed throughout; the flip requires no airspeed, and is initiated from the hover at a safe height. As I keep stressing, you must learn your manoeuvres into wind – I think the new 3D flier often overlooks this. That way, you achieve some free lift from the rotor disc because it acts more like a wing on a plane, and there is far less chance of your model feeling soggy or out of control due to rotor vortexes, and flying through your own turbulence.
With the familiar approach to your loop, try slowing the speed down by half. At this reduced velocity, we lose much of that free lift which would normally take the model up to the top of the loop; to compensate, you need to add more power, and more back-cyclic.
Let’s say we are hovering 100ft up, and into the breeze from your favourite side. Now, if I were to perform a back flip I would first need to apply positive collective, because this will give my helicopter the initial spring upwards. Once I can see it climbing, only then will I start to add back cyclic – this could be as much as full-stick, depending on how much height is gained in the initial spring. Once the helicopter has reached the vertical first quarter, I can reduce the collective, and start to think about bringing ‘negative’ in when the helicopter reaches its inverted second quarter; as soon as the helicopter is inverted, I keep hanging on the rear cyclic, and will then add full negative to spring the helicopter back to the third quarter, which should now be tail-up and returning to the upright.
It is actually very easy to get a grasp of the elevator flip. Given enough height, you could just leave back cyclic in from the hover and zero the pitch, before simply tumbling down; then, you’d recover after one 360º tumble. Another nice variation would be to initially perform the flip as described above but then, as soon as the helicopter reaches that nose-down, final third quarter, just recover as you would for the downward section of a stall turn. More on that in a minute.
Turning our attention to aileron flips, these have the same rhythm as an elevator flip in terms of the sequence of control inputs. I prefer to teach this manoeuvre from the tail-in hover, but performing into wind – I think we need a breeze coming on to the pilot this time.
Looking at the rear of the helicopter, we can achieve a good understanding of just how the inputs from a pilot move the model around a flip, so bear that in mind as we move through the following description. Before I attempt any new manoeuvre, I always make sure I have a good idea of the controls required, and visualise just how the manoeuvre should look. Also, I will fly the manoeuvre on my simulator, to gain the instinctive reactions needed to carry off a new trick.
When performing an aileron flip, there’s a great risk of picking up some backwards speed – you will have to be aware of, and ready for, this. For those not familiar with backwards flight, you could apply a little forwards input in the upright position, just to provide some forward momentum to the manoeuvre. From experience, I’d say the new ‘hotdog’ pilot will have a tendency to mix some back-cyclic when applying left or right aileron; with so much going on, this can be a very hard habit to get out of. Once again, you have been warned.
To start this manoeuvre, move out a bit further than you would normally like. That way, any non-intentional backwards flight can be dealt with before you go flying over our heads! Okay, so off we go again… spring the helicopter up and over, in the direction you prefer to roll (for me, its right, but others may roll left). What you are looking for is a nice, semi-circle leap to the inverted, and then another semi-circle leap to upright.
A popular habit among fliers is to add a small amount of rudder at the same time as you apply the collective. When learning these new, tighter manoeuvres, it is VERY important to be accurate with the transmitter movements, and to discipline your controls accordingly – so, what I’m saying is, be conscious of what you are doing, and try not to get into bad habits.
THE OL’ ROUTINE
Lets try to fly a small sequence. Start with a nice half roll, making sure you have plenty of altitude and a good amount of forward speed. Next, roll with a little nose-down attitude, keeping your momentum up as you go into a clean half roll to the inverted. With negative pitch, now apply some back-elevator as you finish with a half loop to make an exit to forward, upright flight and positive pitch.
How about this as an alternative: fly into wind, at a medium height, and then complete a full 360º roll, remembering to keep the speed up with a little forward cyclic in the upright stages. Then, pull up to perform a loop. On the last third quarter of the loop, which should finish just to the downwind side of your position, flatten off the loop a little and click into the hold, finishing with a standard approach auto in front of you.
To move forwards and make progress in 3D flight, the ability to link manoeuvres and split manoeuvres down is necessary. From loop to flip is one variation, and from that comes the size of the flip because now, we’re dramatically changing the basic manoeuvre which started out as a loop. So, from the flip to the inverted, why not flip back again with opposite cyclic, leaving you in the position you started from?
Unfortunately – or fortunately, whichever way you look at it – 3D flight will always lend itself to a new manoeuvre just when you’ve started getting the hang of the last one. With these flip manoeuvres, we are now starting to venture into the realms of sustained inverted flight; in fact, this is a very good way to learn inverted, because you can get a feel for it knowing that completing a roll or loop offers an easy escape route.
Using either flown or flip versions of the roll and loop, try hesitating the manoeuvre at the inverted stage. Gradually extend the inverted periods, remembering that to escape involves the continued application of cyclic for the given manoeuvre. Remember to only apply the smallest corrections possible – after all, you’re trying to anticipate and develop a feel for your model.
At this stage of flight, i.e. entering the realm of 3D, your model has to work a lot harder, and so does the gyro in more stationary manoeuvres, where it has to keep the tail from moving about. It is now more important than ever to maintain and inspect your model on a more regular basis.