Wednesday, March 12, 2008

Lessons : Inverted

Here I got Flying Lesson From, i'm sure this lesson will help you Guys.....

Lesson objectives:
1. Begin basics of inverted flight.
2. Master inverted hovering tail in/nose in/side on.
3. Become confident in handling the helicopter in forward inverted flight.
4. Safely control the helicopter through turns in forward inverted flight.

Flying inverted is a great party trick. Do some inverted flying in front of some spectators and they'll think you're the man. However, while inverted used to be 'the' maneuver, it has now become a fairly basic requirement in order to execute some of the harder 3D (and even F3C) maneuvers.
Some would say you can do the more basic 3D maneuvers before learning inverted. However, I counter that by saying "what happens if you find yourself inverted in a critical situation?". There's a good chance it's not going to end well, so continuing to subscribe to the 'walk before you run' theory, we'll do inverted now.

When I first learned inverted flight, I must have spent a full week of nights on the simulator before I tried for real, and I would recommend this to everyone. You'll learn much faster on a sim.

Your heli should be able to pull at least 9 degrees pitch both ways in Idle Up 2. Set your pitch curve for 0 degrees at mid stick. Ensure you don't have any binding at full pitch (both positive and negative) while adding in a little cyclic.
For the throttle curve, start off with something like 100, 70, 50, 70, 100. Remember, you're aiming to hover at points 2 and 4, so you don't want the engine screaming it's nuts off there, I wouldn't recommend anymore than 70% throttle at either of these points.
If your radio has some extra mixers (or if you've got a radio with a dedicated SWASHPLATE function that mixes in throttle with swashplate movements), then become familiar with the use of these functions. They'll become very useful when we get into more advanced aerobatics. I wouldn't recommend complicating things right now by setting them up, but become aware and familiar with their operation.
If you've got a heading hold gyro, it's a good idea to setup Idle Up 2 for heading hold. That way the tail can look after itself while you're trying to come to grips with the cyclic controls.

Orientation Tricks
Learning inverted isn't easy and takes a bit of practice. Many people can hover inverted, but can they fly circuits?
I found that inverted was easier than tail in at first. Not sure why, but it just was.

This is exactly the same as 'upright' flying. If the heli is inverted nose in, treat the aileron the same as upright nose in and vice versa.

This is one of the harder ones to learn. When the heli is inverted nose in, you 'push' the stick to push the heli away from you, and 'pull' the stick to pull it to you. Ofcourse this is reversed when tail in. This one here just takes time.

Rudder isn't easy to learn either. The trick I use now is to 'steer the bit closest to me'. For example, when the heli is nose in to me, and I want the nose of the heli to turn to MY right, I push the rudder right. If I want it to go to MY left, I push the rudder left. Same deal with tail in, if I want the tail to move to the right, I move the rudder to the right.

I don't have any tricks for pitch! You've just got to remember that down is up and up is down!!!

Getting Started
The best and most safest way of entering your first inverted flight is by trying to hold the heli at the top of a loop.
Enter the loop at a nice comfortable height in ID2, and as the heli reaches the inverted stage, release the elevator back to neutral and increase negative pitch to 'prop it up'. Hold it there for a few seconds until it starts to drift, or you become uncomfortable, then ease back on the elevator and continue on with the loop. The aim of these first attempts is to get the hang of the cyclic controls, what does what etc.
Continue on with trying to hold it at the top of loops. Make small determined stick movements. If the heli starts moving towards you nose in, push the elevator stick forward a little, if it's moving sideways, correct it as you would if it were nose in.
Check your inverted climbout ability by giving it a stab of negative pitch to try and gauge how quickly the heli climbs out. This will ensure that if you get in trouble, stabbing on the negative pitch to gain you some altitude is going to be effective.

Once you can stop the helicopter drifting off by itself and can maintain a stable hover at altitude, start exploring the elevator cyclic controls. Gently pull back on the elevator to start the heli in slow forward flight towards you, move it along ten meters or so, then gently push on the elevator to bring the heli back into a hover. Then try the same with aileron. Ofcourse you will need to make the appropriate pitch changes as you would if you were doing this same exercise upright. At all times, if you feel it getting a bit 'uncomfortable', bailout, take a breath and try again.

When you can maintain a stable inverted hover and can move from one place to the next confidently, start getting the helicopter lower and lower, ensuring that you have a bailout plan in your head. For me, this plan is pushing forward on the elevator and down on the pitch so that the heli is climbing and flipping to upright if I 'get lost'.

Forward Flight
Now that you can hover inverted in a controlled fashion, it's time to work on the forward flight aspect. Not surprisingly, it's much like when you take your first steps into upright forward flight. Take things slowly.
I recommend you get comfortable with hovering the heli inverted side on to you. It doesn't have to be at low level cause we'll not be going that low to start with. Initially, we're going to start flying inverted back in forth from side to side in front of us. The reason for this is we don't want to be flying at us incase of a 'brain fade' and the wrong stick is pulled and you have an upside down hedge trimmer racing at you, and that is not what we want.

Just as you practised the hovering, enter the inverted forward flight from the top of a slow loop. Do not get too much speed up, take everything slowly. As the heli comes over the top and inverted, slowly start applying some forward elevator and some negative pitch so that the heli continues straight on in forward flight. Not too much else the heli will stop and start flying backwards, and not too much negative pitch before forward elevator else the heli will pick up speed very quickly!

When I was doing this, I would let the heli 'glide' past me with as little input from me as possible, I would give little inputs so as not to 'upset' the heli. Let it continue past you until you are ready to stop. Do this by pushing forward on the elevator for a forward flip. This will gain you altitude instead of losing it. Get yourself sorted, and then do the same again, but going in the opposite direction. Continue doing this until you are comfortable controlling the helicopter in straight line forward inverted flight.

When you can confidently control the heli in forward inverted flight, it's time to start adding some turns into the mix. The issues here are timing the rudder with the aileron and elevator. The aileron works exactly the same as it does right side up. However, when you enter a left hand turn, you're adding some left aileron, some right rudder and a little forward elevator to bring the nose around. The aileron and rudder work on the 'together/apart' rule, where if aileron moves toward the center of the radio, so too does the rudder. If the aileron moves to the outside of the transmitter, so too does the rudder. This rule holds true for both Mode One and Mode Two radios.

Enter inverted forward flight in the same way as you did above, and as the heli glides past you from left to right, start executing a left hand turn by adding a little left aileron and a little right rudder, as the heli begins to turn, add in a little forward elevator to stop the heli from diving. Continue to hold this in as the heli turns, again making small movements. As the heli completes the turn and begins to head back down the track from which it came, let it continue for a while, then either forward flip, or aileron roll out to upright. Complete this maneuver again and again until you are comfortable with making banking turns. Make both left and right hand turns as well as nose in and tail in turns.

1. Always have a bailout plan. Most of the time, I do forward flips as they gain altitude (unless flying backward inverted).

2. Be smooth on the sticks! Sudden movements can accelerate bad situations!

3. Make sure that you have a good inverted climbout. Adjust your pitch curve until you get one. I've flipped a heli over and hovered inverted quite low to the ground and gone to climb out and found the heli climbs at a snails pace. Not good if you have to bail quickly!

Bringing it all together
Once you've sorted out the 'turning' business, it'll pretty much all come together and you'll get to a stage where it doesn't matter if the helicopter is right side up, or up side down. It's when you've achieved this, that you're ready to get into some of the more demanding 3D maneuvers.

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