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Friday, January 4, 2008

How to Get Started in RC Night Flying

Before you begin night flying, it is important to understand some basic concepts about how the eye works. I am certainly no optometrist, and I couldn't describe the differences between the cornea and a cone, but I can convey to you what I have learned through experience.

The eye is sensitive to contrast. The greater the contrast between objects, the more detail the eye can discern. That is why it is important to fly only when it is very dark (preferably on a clear, moonless night, away from the city) for your first few flights. This will actually make it easier to see your airplane, because the darker it is, the wider the pupils of your eyes will open, and the easier it will be to see the lights of your aircraft, for they will present a high contrast against the blackness of the sky. Also, it is important to keep in mind that your eyes can take up to 25 minutes (or more) to fully adjust to darkness after being exposed to bright light. The brain works in conjunction with the eye to protect the optic nerve and the retina from over-stimulation, therefore the eye is much quicker to respond when adjusting to light than it is when adjusting to darkness.

Many night flyers will argue that you need intense lights on your airplane to make flying at night possible. While this may be true within one school of thought, I say there is a better, more effective (and efficient) way. It takes a lot of power to generate intense light, and it is unfortunate that many night flyers configure their high power lighting systems in such a way that about 99% of the generated light is wasted!

A good lighting configuration is essential to a successful night flight. Remember that when you fly at night, your perspective will be very different from what you are used to seeing during the day. In the daylight, you can see your entire aircraft. At night, all you can see are the lights that you have on your aircraft. In other words, you don't fly an aircraft at night - instead, you fly a pattern of lights. You have to use some imagination to translate that pattern of lights in the sky into something that resembles your aircraft so that you can determine its orientation.

I have found that the simplest effective lighting configuration consists of four (4) points of reference: wing tips, nose and tail. The wing tip reference lights help you determine the orientation of the aircraft along the roll and yaw axis, whereas the nose and tail reference lights help you determine the orientation of the aircraft along the pitch and yaw axis. The combination of all reference lights forms a sort of "T" pattern, making it relatively easy to judge the orientation of the aircraft. I suggest you start with a simple, effective lighting system until you determine whether you like night flying or not. If you decide to continue, then you can pursue a more elaborate lighting system.

Probably the simplest way to prepare a model airplane for night flying is to purchase some cyalume chemical light sticks and use clear packaging tape or strong rubber bands to affix them to your aircraft. It is important to be able to see the light sticks from most any angle, regardless of the orientation of your aircraft, so the number of light sticks you use may vary depending on your aircraft. I would also suggest you fly a slow-flying trainer type aircraft for your first time up until you get a feel for it. Just like anything, you have to learn to walk before you can run.

It is best to affix a light stick on the very end of each wing on the edge of the wing tip and/or have them protrude from the wing, preferrably toward the nose of the aircraft. This gives them maximum visibility from above and below, and also allows them to be visible from the front and sides. You will need visibility from the front for when it comes time to make your landing approach. It has been my experience that the orientation in which the plane is least visible at night is when it is coming directly toward me. Therefore, all of my lighting configurations include some forward-facing wing tip lights and a light in the nose. I might also suggest that you use a different color light stick on each wing tip (traditionally, red on the left and green on the right). This will help eliminate disorientation problems that accompany certain aircraft positions.

The lights in the nose and tail should be visible from above and below as well. You might think at first that you would only really need to light up the bottom of the aircraft, since one has to look up to see the airplane. However, the top of the airplane is actually visible perhaps more of the time than the bottom, since it tends to bank toward the flight line when making turns around the field. The bottom really is only visible when flying overhead. But it is necessary to be able to see both the top and the bottom of the aircraft. Therefore, there is a good chance you will need two light sticks in the nose. You can generally get by with only one on the tail if it is mounted vertically up high on the fin.

I cannot fully emphasize the importance of being familiar with the plane you want to fly at night. The more comfortable you are flying it during the day, the easier it will be to make the transition into the night. But don't be fooled by your confidence. No matter how well you feel you know your aircraft - no matter how long you have been flying it - it will be a different experience flying it at night for the first time. Do not plan to do anything fancy during your first few flights, because your first few flights will be used to learn some new skills (or at least sharpen ones you already have). On my first night flight, I flew a plane that I had been flying for many years. Taking it up at night seemed almost natural. But that's only because I was already so familiar with the aircraft that I knew what to expect and could accurately predict its movements and orientation. However, on that first night, I felt confident enough to attempt a loop. That's when I learned just how different night flying was. I almost lost my airplane, because the lights fooled me and I lost my perspective of the plane's orientation (mostly because both wings were the same color). I gave it quite a few incorrect control inputs before I regained perspective and recovered. I did nothing more than fly around in circles after that.

Probably the most important thing you can do before making your first flight at night would be to relax, close your eyes, and imagine your first flight. Plan your flight so you know exactly what you are going to do, and don't plan to do anything more than take off, fly around in circles, and land. That will be enough for your first flight. The objective of your first flight should be to become familiar with how your plane looks in the sky, and how the pattern of lights can play tricks on you in certain orientations. The important thing is to remain calm. Be as aware as you can be of the orientation and direction of the plane. If you lose perspective, the disorientation should be only temporary - watch the plane come around until you can identify its orientation in a new position before issuing additional control inputs.

It also helps immensely to have someone with good eyesight stand next to you to help talk you through any disorientation you may experience. An extra pair of hands is also helpful when preparing your aircraft for flight. Chances are, you will need a flashlight or some source of light to use while refueling and starting your engine. If you have an assistant, have him or her hold your plane for a few minutes when it is ready to launch, to give you a chance to close your eyes and allow them to adjust to the darkness after having been exposed to the light in the pits. When you're ready, give the signal to launch, and enjoy the ride!

Perhaps I should have mentioned before this point that once you get the aircraft into the air, there will certainly come a time when you will have to bring it back down to the ground. Landing is probably the most difficult night flying maneuver, especially if you cannot see the runway. Before flying at night, you should have a good mental picture of the runway as it looks during the day. Pay close attention to how your plane looks on approach, touch down, and taxiing on the runway during the day. This will be of some benefit to you in the dark, especially if you stand in the same place to fly at night as you do during the day.

Aside from having a mental picture of the runway, it is good to have some reference of where the runway is at night in case you tend to turn or wander from your post while you fly. Some night flying enthusiasts may argue that you need to be able to see the runway in order to land. I have heard some amazing stories related to this. One in particular involved lining up ten automobiles with their headlights on just to light up the runway. This, to me, is ludicrous. Pardon the judgement, but ten automobiles lined up on the flight line is overkill, not to mention inefficient! It could also present itself as a safety hazard, creating lighting conditions that could interfere with the pilot's ability to see in the dark.

My experience has demonstrated that one does not need to be able to see the runway in order to land, any more than one needs to be able to see the airplane in order to fly at night. If you can fly by lights, you can land by lights. Therefore, all you need are a few (or just a couple) reference lights on the runway to let you know where the sky ends and the ground begins. Probably the simplest way to add reference lights to the runway would be to crack a couple chemical light sticks and toss them out on the ends (or wherever they work best for you). A friend of mine uses a couple of homemade lights consisting of a few LEDs and some old rechargeable NiCd batteries, providing just enough light to mark the runway, and they last all night long!

Chemical light sticks have a relatively short usable life span, but they should be adequate enough to get you through your first night flying experience. And don't push it! If you notice the light begin to diminish in the light sticks, making it even a little difficult to see your plane from a distance, then it's either time to land the plane and go home, or put on some fresh lights.

Flying with light sticks is not the best way to fly at night, but it is probably the simplest. Unless you happen to know someone who flies at night and can quickly rig up a lighting system for you to try out, using light sticks is a good quick-start approach to use. The ideal situation would be to fly with an experienced night flyer who has a proven lighting design and who would be willing to let you fly his plane (just make sure you fly the plane during the day to become familiar with it).

Your success and enjoyment with night flying will be solely up to you. Relax, have fun, and progress at a natural rate. Don't try to push it. There are a number of safety considerations to keep in mind while flying at night that you may not have considered in your daytime flying. If you are sensible, reasonable and patient, you can expect to be flying happily at night long into the future.

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