Here is the next RC Helicopter flying training lesson to give you the real taste of flying RC Helicopter in this hobby. Today we will learn to hover RC helicopter at much higher altitude and will fly RC helicopter at a much faster speed. This one is an advanced lesson of your RC helicopter flying lessons. We will learn about transitional lift and will see its application in the forward flight. We will have large flying circuits around our fixed position, which is similar to the earlier lesson but the difference is of the flying speed and the altitude. Will be starting slowly with a smaller circuit and slower speed and will gradually increase the circuit diameter and the speed too. So, practically we will flying a 100 to 150 feet in diameter circuits with the speed fast enough which will demand you for bank it a little to counter the centrifugal force which tries to pull it outwards. To be able to fly RC helicopter at that much of a speed, you will have to keep the altitude high enough too anywhere 15 to 35 feet. You are thinking right that today’s mistake is going to cost you dollars.
Preparing your RC helicopter for the flying training lesson:
You will have to increase the collective pitch range which must have been at the beginner’s learning setting by the RC helicopter manufacturer for most general flying. Most of the RC helicopters come with the setting of minus -3 degrees negative pitch, at low stick and plus + 10 degrees positive pitch at high stick, not more than that. You will have to increase the dual rate through on your right and left roll rate cyclic too in order to get the roll cyclic controls more responsive. You can leave the pitch cyclic dual rate as it is but if you want to have more pitch control you are allowed to do that.
What is transitional lift?
When you start to hover RC helicopter and then get it moving, you might have experienced transitional lift during your earlier RC Helicopter flying lessons. The transitional lift is the extra lift produced when wind or moving air collides with moving rotor blades. Actually the speed the wind is passing through the moving rotor produces equivalent lift to the RC helicopter as if it was moving with the speed equivalent to the wind speed. The rotor system becomes a bit more efficient when wind pass through it hence produces more lift. This effect is called ‘effective transitional lift’ in the real world of helicopters or simply ETL. The increased efficiency is directly proportional to the velocity of the air passing through the RC Helicopter blades. Effective transitional lift is added with the speed your RC helicopter is moving since ETL depends on the air speed not the ground speed. You may understand with this small example: if you are hovering your RC helicopter facing the wind and the wind is blowing at 30 km/h, the ETL produced will be equivalent to the lift created by RC helicopter moving at the speed of 30 km/h provided there is no wind.
Transitional lift is produced even when you fly rc heli backwards or sideways or when you see tailwind or cress wind. The amount of air passing the rotor blades will produce either by RC helicopter movement or wind will create Effective transitional lift. We only used forward movement of your helicopter in the above example because that is what we are going to practice today.
Having collective pitch RC helicopters is what is needed to control ETL, that is why we the real RC helicopter Hobby people stay away from fixed pitch RC helicopters. I asked you to start your rc helicopter flying lessons in a calm day when there is no or very little wind because of ETL. If you were to start flying your RC helicopter in gusting wind and while hovering it you will experience sudden bounce in the hovering height of the RC helicopter. As a beginner of RC helicopter flying you might not be able to react fast enough to control this constant shift in lift and might have come across a crash, which would have caused your motivation to break and a hole in your pocket.
One very practical example I want to give to make you understand the practicality of effective transitional lift effect. What do you think will happen when you are flying a large circuit at 30 km/h and the wind is gusty at 30KM/h? As soon as you will point nose into the wind the ETL will double the lift and it will be 60 km/h. Well now that you complete half the circuit and wind is gusting from your tail end…. Yes the ETL will be zero and your RC helicopter will face a sudden decrease in lift and drop. To counter this you will have to increase the throttle or collective. You need to remember this while doing fast circuits in high velocity winds, you will have to increase throttle when turning opposite of wind direction to save your RC helicopter from sudden drop and an ultimate crash. This is specially required when you are flying large RC helicopters and at lower heights. Do this or learn the lesson the hard way…
The point of explaining transitional lift in detail was to make you understand the how your RC helicopter is going to behave in your forward flight RC Helicopter training lesson and how to control the sudden change in lift when your move in or out of the transitional lift effect.
RC helicopter Flying training Lesson:
You will be required to practice going into and coming out of transitional lift before getting into fast circuit circle. You will also be comfortable at RC helicopter flying left and right of your side which means at right angle to you; earlier lessons have already prepared you for this. Your pre flight checks should be automatic by now… hope you have done them.
You will start by hovering 5 to 6 feet above the ground and then turning it either left or right of your side, whichever is comfortable to you. Now start giving a little forward cyclic to get it moving forward at around 6 to 8 km/h only fast walking pace. When it gets 25 to 30 feet away from you stop it at a hover. What do you experience? You must have seen that RC helicopter have gained the altitude without your increasing the throttle/ collective. You just experienced transit experienced transitional lift.
To counter transitional lift effect, you will have to increase throttle/ collective when you come out of the forward flying back into the hover and will have to decrease the throttle/ collective when coming into forward flying into the wind to maintain the altitude. This will take your practice and focus to have good hands on it. The more you will practice it the more it will become your sense, and sooner you will be applying counter collective/ throttle for transitional lift without even knowing you are doing it.
Let’s do the RC Helicopter fast forward circuit flying lesson:
The only difference in last RC helicopter flying lesson and today’s one is that in the previous one you kept the circuit small and the velocity of your RC helicopter was not that fast. Today you will be flying fast larger circuits with more altitude.
Start with the speed of last RC helicopter flying lesson slow and with small circuit, you may want to fly it counter clock wise or the clockwise whichever suits you( you must have found your rotation type during the last exercise). Now start increasing the speed of your rc helicopter and start increasing the circle with gradual increase in the altitude. You may not want to fly too fast or it will create dizziness. You may start with a circle of 50 to 60 feet in diameter with an altitude of 10 to 12 feet in the air with a speed of 15 to 20 km/h. After completing few circuits start decreasing the rc helicopter and bring the diameter of the circle smaller to the size of last RC helicopter flying training lesson. Safely lad you rc helicopter and take a little rest.
Analyze your performance with the larger and fast circuits, if you feel nervous, you might want to spend more time practicing the last rc helicopter exercise and make yourself comfortable. When you feel comfortable, start the same large circuit with same speed and altitude but in opposite direction which will most possibly be in the clockwise direction.
This RC helicopter training should make you confident and comfortable with flying rc helicopter in 60 feet circle both clockwise and counter clockwise directions. Now it’s time to make the circles larger and faster with higher altitude. Do 80 feet diameter circle this time and go to 120 feet with more speed and with altitude of 30 to 35 feet. The larger the circle with more speed you can fly without getting the dizziness from it. You must maintain the higher altitude in order to give yourself chance of making up with your mistake with quickly reaching the ground.
Once you get comfortable with flying faster in both directions, you must start banking the rc heli. It will be felt very natural to you when flying clockwise give right cyclic and give left when flying counter clockwise. You will have to pull back on the cyclic slightly to help the heli on the banking turning edge. RC helicopters much behave like RC airplanes when flying fast and this effect may have been experienced by you if you are an RC airplane or RC Jets flyer.
While slowing down your RC helicopter in smaller circuit, don’t forget to increase throttle/ collective to make up for the reduced amount of transitional lift. I believe by the time you reach this stage you will be doing all this automatically without even realizing.
Hurray!! You have just completed a very important RC helicopter training flying lesson which must have shown you the actual potential of your RC helicopter and have made you a little more addicted to RC helicopter hobby. You can actually record your length of RC flying lesson on video and see the fly RC helicopter DVD video after you have completed the lesson to see what was going on. By seeing your own fly RC helicopter video you will learn a lot and improve faster.
The next flying lesson will be more thrilling…. Even I can’t wait to write about it. Till then..
Happy flying!
Tonja
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