Hovering By James Goss      It seems that in the field of 3-D flying, hovering has become the benchmark that most pilots use to choose their fun fly planes. I have been trying to hover some of my models now for about two years and have had good luck with some and none at all with others. Now I am not talking about hovering your plane into a head wind, the type of hovering I am in reference to refers to hovering your plane with its nose pointed straight up and with no wind at all. Hover, bring the plane down close to the ground and then pull back up to repeat it again. Every now and again let it do a torque roll and then lock it back into a stationary hover. A series of torque rolls also looks neat, especially if the wind is blowing the plane down the center of the field. I think any plane will hover if it has enough engine power and control surface movement. How long it stays in a hover depends a lot on the plane as well as the pilot.      Let me say at the beginning of this article that hovering a large or small model plane can be dangerous for other pilots as well as for you and all the spectators around. 3-D flying deals with maneuvers while the plane is at or near a stall condition. A hover is about as stalled as you can get. You already know that a plane can do some crazy things when it is stalled and sometimes you have no control at all over the plane; it has a mind of its own. This is where it can get dangerous if you are flying too close to other people. Pilots that are flying their own planes are not watching what is going on with the other planes in the air. I think it is a good idea to practice taking your eyes off your plane and looking around to see what the other planes are doing. I always do this during each flight and have no trouble finding my plane again; it just takes a little practice. When you take your eyes off your plane in flight it is still going to be in the general vicinity when you look back, it is not going to just fall out of the sky. (Unless you are flying a super fast plane, in this case it may be in the next county when you look back.)  If possible always hover at a location across the field and then if you loose control your plane can hit the ground without doing any damage to anyone or anything other than your plane. Remember, when your plane falls out of a hover it takes a lot of engine power to recover without loosing any altitude, most planes do not have it. At our club field I try to do most of my hovering across the field and over a soybean field. In all cases you can't predict which way your plane will go when it falls out of a hover. It may do one thing this time and something completely different the next time. So always have a large safety zone around your plane that will give you plenty of recovery time.      So what does it take to hover a model plane? First you need an engine that has about a 1:1.5 or greater weight to thrust ratio. An engine that has enough power will pull your plane straight up from a hover with good acceleration. A lot of fun-fly planes with small engines will hover the plane for a while, but when it falls out of the hover it will loose a lot of altitude fast. This is not what you want if you are hovering three feet above the ground. The engine has got to pull your plane straight up and not let it fall to the side. Next it takes a plane that is built for hovering with plenty of control surface and control surface movement.  When the plane does fall out of its hover you may need a lot of rudder or elevator to gain control again. I am talking from 45 to 60 degrees of control surface movement. Most important of all you need a reliable engine, one that will not quit while your plane is at ground level. Even at a few feet above the ground when a model falls due to a dead engine, most planes will still receive a lot of damage. I have seen giant scale as well as small planes have their fuselage break into several pieces when they fell from a height of only three of four feet. I think it is safe to say that it is possible for all engines, gas and glow, to quit at any time during a flight. You may have fifty flights without a dead stick and then it happens when you are least expecting it. So relinquish the thought that your engine is above quitting on you during a hover, it will happen sooner or later. If I am planning on a lot of hovering during a flight I like to adjust my engine on the rich side because when the nose stays pointed up for a minute or so the engine may go lean and quit. I also like to fly a few circuits to make sure my engine is at normal running temperature and is running reliable in the vertical mode. A while back I was just getting ready to enter my first hover during a flight and had about 40 or 50 feet of altitude. The engine spit and sputtered a few times and down she came. The plane was a 60-inch fun fly with a YS-120 engine and a total weight of 8.5 pounds. I had just enough altitude for the plane to recover and level up before it hit the ground. So it is important to know how much altitude your plane needs to recover and always use this amount or greater for your first hover of each flight. When your engine quits and gravity takes over, your plane will try to fall at a rate of 32.2 feet per second per second while it is in a vertical attitude. This means that if your plane is at a 50 ft. altitude and your engine quits, it will take only 2.05 seconds for your plane to hit earth. Remember that during the first second the object only falls half the distance, about 16 feet because it is going from a standstill. So the first second averages out to half of 32.2.      There is a lot of controversy about which prop to use while hovering. Do you need a large diameter with low pitch or a small diameter with large pitch? I think it depends on your plane and all planes seem to be different to some degree. I know on my smaller fun fly planes a large diameter and low pitch work best for me. On .46 size planes I like to use a 12.25x 3.25 prop. It gives my planes good speed regulation while going vertical. Remember that prop diameter is for thrust and pitch is for speed. All we need in a hover is enough thrust or pulling action to cancel the gravitational pull of the earth. The only speed we need is the air flowing over our control surfaces to correct for a fall out.  While in a hover the low pitch prop seems to create less torquing of the airplane. It is easier to hover a plane when it is stationary and not trying to torque roll. I will talk about torque rolls later.      Now that you have a plane and engine needed for hovering all you need to do is practice. Entering the hover can be from any position that you like. Most pilots will bring their plane in as if they were going to land it and just before it touches down they will give it a little throttle and pull vertical. Of course they didn't learn to hover like this. You will need to start out at a safe altitude, maybe 100 feet or so to get the feel of it and as you get better you can work lower to the ground. You may wonder why we hover so close to the ground. Not only does it look good it is much easier to hover when you can see your plane. You must be able to see when your plane is on the verge of falling out of its hovering position or what I like to call its sweet spot. If it is close enough you can see this and head it off at the pass so to speak. So for good hovering it is almost a necessity to be close to the ground (the danger zone) for that reason. If you are hovering at 300 feet in the air you may not be hovering at all, your plane may still be going up and you just don't realize it. While in a hover I choose to have the top of the fuselage face me and I watch the nose and not the tail. For me it is easier this way because the rudder is not reversed. If the plane's nose falls to the left I give it right rudder. If it falls to the right I give it left rudder and so on. The elevator also works better for me this way. You are still flying its just that your plane is not moving, so it is logical to use the same train of thought as you do when you are flying with the wings producing lift, up is up and down is down.      Next, how do you get your plane to descend?  Once you learn to hover you will want to learn how to get your plane to loose altitude while keeping it in a hover. Of course if you chop your throttle the plane will reduce its altitude, but keeping it in a hover is a hard trick to learn. You have got to manage the throttle by reducing and increasing it in small increments. If you give it the gun all at once your plane will probably start to torque roll and if you can't handle torque rolls you will loose the hover and the plane will fall to one side or to the front or rear. The way I do it is to gently reduce the power and let the plane fall a foot or two and then stabilize it again by giving it more throttle. You will normally need to give it more throttle than it requires to hold it in a hover until it stabilizes again and then back off. When it is back in its sweet spot chop the power again and repeat until it is as low as you want it. If everything is going well at this time you may want to pull back up and do it all over again or fly off in a knife edge. I have one plane that I can get to descend if the wind is not too strong and I am having a good day. Getting a plane to descend while in a hover is one of the hardest 3-D maneuvers I have tried. With practice it is becoming a little easier as time goes on.      I guess the overall most impressive 3-D maneuver that we can do is the torque roll. Some planes will torque better than others and it depends mostly on the engine. For every action there is an equal and opposite reaction (who was it that said that?) If your plane is in a hover it will eventually start to torque roll, some faster than others, but it should start. If it rolls around fast with a uniform rate it is easier to keep it under control because you only have to correct it when it is in your favorite position. If it rolls around and stops with the reverse side of the fuselage facing you it will take some quick thinking to input the correct controls. Rudder is now backwards and what makes it even harder is that the elevator is also backwards as compared to its operation while the fuselage top is facing you. Once you learn to hover for a few seconds you will need to practice the hover with the fuselage turned to the opposite direction than that from which you learned. The first time you let the plane rotate around and you keep it in a good hover as it rotates, you will feel a real accomplishment. It is always a good feeling to know you are advancing in any hobby or sport.       It seems to be true that a larger plane will hover better than small plane if it has enough engine power. First of all you can see the plane better and it doesn't need to be right on the ground to make out what is going on. A large plane seems to fall out of its hover at a slower rate so you have more time to think and react with the correct inputs needed to keep the hover going. Again let me say that there is no prettier picture than a large giant scale plane doing torque rolls a few feet above ground level. Of course everybody interprets beauty in his or her own way. What's enjoyable to me may not be so for others. But overall I think most all pilots will enjoy seeing a plane hover in the grass and then pull away still in one piece.