For beginners or airplane pilots that make their fist few attempts flying a helicopter we will offer a brief introduction to the main controls of a helicopter.
Pull up = Lift off
In the cockpit there is a lever left of the pilot seat and left of the copilot seat which controls the blade pitch angle of all blades collectively. This control is called the collective pitch lever. The collective lever is pulled up to increase the blade pitch angle. That increases the lift of the rotor and the helicopter starts to rise up. That's right, we usually don't increase throttle or rotor RPM on a helicopter, we just change the blade pitch angle.
Left/Right Cyclic Roll = roll left/right
Forward/Aft Cyclic Pitch = pitch nose up/down
The stick between the knees of the pilot is called the cyclic in a helicopter. It adjusts the individual blade pitch throughout the revolution of the rotor in such as way that the aircraft's fuselage moves in the direction that you point the cyclic to.
If you move the cyclic forward the helicopter tilts forward and the nose goes down. Eventually the aircraft accelerates and you increase airspeed.
If you move the cyclic backwards the helicopter nose goes up. The aircraft is slowing down again and can even fly backwards.
Moving the cyclic to the left lets the aircraft roll to the left side. If you keep that bank to the left the aircraft will start drifting to the left and get quicker and quicker until the tail stabilizer acts like a weather-vane and rotates the nose of the aircraft into the direction of travel.
Move the cyclic to the right to roll to the right.
During hover the cyclic is almost completely neutral. Very small inputs are required to change the attitude of the helicopter. If you are practicing the hover perform small and very short inputs. Usually a small and brief nudge already creates a significant change in the attitude. Do not hold the stick deflected until you see the aircraft accelerate. Try to control just the fuselage attitude instead. If you see the attitude rolling away you should add a small input to correct for that attitude change. Add a small input to change the attitude and then wait to see if the speed of the aircraft decreases or not. If you keep holding the stick deflected the aircraft will continue to roll and you will see extreme pitch or roll attitudes before your helicopter even starts to move.
No manual throttle inputs needed
When you increase the blade angle with the collective pitch input your rotor blades will bite into the air and push it down. The air resists that change and pushes against the rotor blades in an actio=reactio fashion. That causes the rotor to be slowed down, so how does the rotor keep spinning and not come to a complete stop?
The answer is the engine controller. A full authority digital engine control (FADEC) changes how much fuel is injected into the turboshaft engine. If you pull the collective and the rotor speed drops it senses the engine computer that and adds fuel into the engine to increase the power output. The engines then speeds up and creates more torque. The FADEC in a helicopter acts like a governor that maintains a constant rotor speed by changing the fuel that goes into the engine.
Left/right tail rotor = nose rotates left/right
Similarly to the collective input the tail rotor blade pitch is controlled collectively. The pilot uses the foot-pedals for this, just like in a plane. Pushing the left pedal forward will make the nose go left. Pushing the right pedal forward rotates the nose to the right.
To maintain a constant rotor speed the FADEC modulates the fuel flow to the engine. The engine creates torque on the driveshaft that is mechanically linked to the rotor. Since the engine sits within the fuselage the whole fuselage starts to rotate relative to the rotor if you change the torque. The tail rotor is there to counteract that rotation and usually the pilot has to adjust the pedal input constantly to keep the nose pointing in the same direction.
In Aerofly FS we assist you by automatically keeping the nose straight with an artificial assistance in the stability augmentation system (SAS). If you push the red button on the cyclic you can disable that automatic heading hold function.
A typical flight with a helicopter begins and ends with a hovering phase. The helicopter is flying just above the ground with close to no forward or sideways speed.
To get into this phase of flight the rotor obviously needs to be spinning with the engines running and both FADEC switches in the FLIGHT setting.
Because the rotor on the EC135 is at an angle to the fuselage floor the aircraft nose needs to point up significantly to maintain stationary. With a pitch angle of about 7 degrees the rotor is actually level relative to the ground.
And because the tail rotor creates significant thrust to stop the fuselage from spinning it creates quite a bit of sideways force to the right. We need to bank left about 3 degrees to keep the helicopter stationary.
So the typical attitude for a stationary hover is a bit nose up and slightly rolled to the left.
During standard takeoff we transition from a stationary hover to forward flight a few feet off the ground. Similarly to an airplane we accelerate down the runway whilst being and then perform a rotation to transition into the climb phase.
To perform a normal takeoff we hold a slight nose down attitude and maintain altitude with the collective input.
Between 30 to 50 knots we have enough forward speed so that the main rotor downwash no longer affects the rotor inflow. The rotor inflow now is fresh new air that we haven't pushed down yet which causes a significant increase in the rotor's lift. The nose of the helicopter will want to rise because of that but we introduce forward cyclic to stop that from happening. The helicopter continues to accelerate until we have left the ground effect at around 50 to 60 knots indicated airspeed. At that point we can gently pull back on the cyclic or reduce forward pressure and even without changing the collective input.
At around 50 to 60 knots the aircraft will start to climb on its own.
Depending on the weight of the aircraft and altitude this maneuver may not be possible. Unlike the standard takeoff we increase the height first before we start accelerating forward.
Then perform a standard takeoff by moving the cyclic pitch forward, pick up speed and slowly transition to climb at around 60 knots airspeed.
A standard approach in a helicopter is very similar to a landing in an airplane. We approach the runway with a typical 3° approach angle but we continue to slow down as we approach the target landing area. We slowly transition to a hover as we slow down. When we are right above the landing spot we can reduce collective and gently touch down.
Unlike an airplane it is common for helicopters to land on taxiways or on helipads of course. The approach procedure is the same for a standard approach and landing.
Similarly to a standard approach we fly towards a desired landing spot at a normal 3° approach angle. But we aim to be 50 to 100ft higher at all time so that we are in a stationary hover right above the landing spot. We then slowly descent vertically. Aim for less than 200ft/min descent rate during this vertical descent.
During this phase it is important to maintain a small descent rate. Otherwise the rotor downwash will circle around the rotor and the rotor will loose a lot of lift causing a very high rate of descent. In this vortex ring state we're pretty much just a falling object. If you find yourself descending vertically very rapidly you will probably not be able to recover from it by just pulling more collective input. Instead you have to push the cyclic forward to bring the nose down and pull collective. That will push the downwash to the side and as you keep falling the rotor will no longer inject its own downwash. It will gain lift again and you can pull up from the dive to fully recover.
When the engine(s) of a helicopter quit the rotor shaft mechanically disconnects from the engine driveshaft(s) because of the freewheel so that the rotor can keep spinning even if the engine stops. From that point forward the pilot has to change the collective pitch input in such a way that the rotor speed is maintained within limits. Raising the collective will cause the rotor RPM to drop. Lowering the collective increases the rotor speed. During the autorotation the helicopter constantly looses energy in form of friction or drag. Because of that we need to trade in either aircraft speed or altitude to gain rotor speed.
When we are flying fast and an autorotation (short “auto”) happens we can first trade our excess speed and even maintain or gain altitude by reducing the collective lever slightly and pitching the nose up with the cyclic stick. Once we decelerated to around 80 to 70 knots we decrease the collective input and start our glide towards the landing spot.
When we are slower than that we first have to lower the collective and enter a dive to pick up airspeed before we can gently pull up.
Depending on the helicopter size we aim for 60 to 70 knots indicated airspeed during the autorotation. We have to adjust the collective to maintain the rotor speed and use the cyclic controls to adjust the flight path.
Find a location where you can land at. A professional pilot really doesn't need a lot of space but if you are still practicing then the entire airport area can be your landing spot.
The approach during an auto may be steeper than you are used to, maintain your 60-70 knots airspeed until you are close to the ground. Then pitch up for the flare.
From here you can take use different strategies.
A) On a hard surface or on a flat grass surface you can keep the helicopter at a level attitude and touch down using the collective input. This is much easier and safer but it can damage your skids when you skid down the runway. When the terrain is rough you could potentially flip over, which is not good. During the last phase and particularly on the ground try to keep the nose pointing straight ahead with your pedals.
B) Reduce the forward speed close to zero before touching down. This requires a nose high attitude when you are close to the ground until the airspeed has dropped so much that the rotor speed decreases rapidly. You only have a few seconds to bring the nose down to a level attitude and touch down using collective inputs before the lift is getting too low and you'll be forced to touch down. During the round out and flare you are running the risk of a tail strike because of the nose high attitude so don't do this maneuver too close to the ground. Using the replay you can judge how close you were to a tailstrike later on.