Autorotation 101

So, you want to learn to auto. Good for you. Personally, I think its one of the best things about flying helicopters! Back when I attended my second funfly in Dallas, Mike Cingari was kind enough to spend a little time checking out my Xcell 40 to make sure everything was ok. He test flew it, rolled it and looped it. Then he did it...he killed the engine on purpose and shot an auto. I was using a Futaba 7UAP radio that Rick had given me, so "on purpose" might have been somewhat a fib. I don't remember Mike setting up throttle hold, but I had read enough books to know it needed to be turned on. The model touched down at Mike's feet. He handed me the radio and said " Three things. Get a Super Tiger Carb, Get a JR10S radio and make every landing an auto." I've pretty much followed his advice, though every landing hasn't been an auto, most have.

An autorotation (auto) is a transition from forward flight to landing without power.

It's important to remember that the model still flies without power. You can turn, and you can control it's speed of descent. You can even climb...briefly. Some machines with special "driven" tails can even flip, roll and pirouette during an auto. Never forget to keep flying after you hit the throttle hold switch.

The Setup

30s can auto just fine. Raptors are great little auto machines. Don't let anyone convince you otherwise. If you follow instructions, there's no reason to crash, but if and when you do (we all do), the 30 will be a lot cheaper to fix.

It's very important that you set your radio up to do autos, even if you don't plan to do any right away. Most radios today have a throttle hold (hold) pitch curve. You should have at the very least, negative 3 degrees at low stick and as much positive pitch at high stick as you can muster. Personally, all of my pitch curves are the same in all flight modes. I have -10 at low stick and +10 at high stick. That is something you can ease into if you want to, but I don't recommend it for the beginner, or the flyer that wants to do a lot of precision hovering. I do it so I can flip into any flight mode without the collective changing.. It also lets me come down very quickly, which is something the beginner shouldn't do. It's best if the throttle hold pitch curve and the normal mode pitch curve are identical, with the exception of the pitch at high stick, which should be as high as possible in hold. Just be sure you have at least -3 at low stick. Flip the hold switch on the ground with the radio on and the engine off. Watch the swashplate carefully. It shouldn't move when you flip the switch unless you're at high stick and then it should add a little pitch, if more is available. If it tilts to one side when you go into hold, look through your radio for something like stunt trim or trim offset. Adjust the trim in throttle hold until you don't see any swashplate movement when you go into hold. Get out your radio manual if you have to.Verify that you actually have some negative pitch at low stick. Pitch gauges lie. Level the flybar and look at the pitch. It should be obviously negative.

Normally, when you flip the throttle hold switch, the throttle should be set to go to an idle that is as fast as it can be, but still not engage the clutch. The exception to this would be during your very first autos, you might want to set the throttle to a faster speed so the clutch stays engaged. This will make the first autos a lot easier and build confidence. Don't go over about 20% throttle though. Just enough to help keep the blade speed up in case you goof. Ease the extra throttle out a little at a time as you begin to realize that it's not necessary.

Pick some heavy blades, if you can. Most kit blades are ok, but heavier blades will make things easier. Avoid any blades that feel extremely light, such as the "foamies".The Raptor 550 stock blades auto great. You don't need carbon or fiberglass blades to auto.

Pick the Place and the Day

If you can, choose a day with a good wind, at least 7 mph but not over 12mph. If it's windier than that, or if there isn't enough wind, just practice making powered descents to a spot nearby, from either side. Before you auto, you should be very at ease with landing the machine where you want to, and being able to land nose in is a real plus. Pick a smooth surface to do your first autos to. This is very important. An asphalt parking lot or closely mown grass are both good places to start. Avoid rough textured concrete and grass that has runners or rough spots. Remove any skid stops you have on the model so it can slide easily. You might even consider putting a 1/2 x 24 inch dowel with a whiffle ball on each end across the skids. This should be a confidence booster, not a necessity. Make sure your blade bolts are pretty tight. You should be able to hold your model sideways and the blades shouldn't pivot in their holders. Tighter is better. Try to pick a site where you have plenty room. The first ones might go long or come up short, so make sure you don't have to worry about dodging obstacles. If you can, paint a target with fluorescent orange or white paint. Make sure it's big enough to see. I really believe that even your very first auto should be to a target. It doesn't really matter if you hit it or not, but it will make you progress a lot faster.

Warm up and Visualize

Go ahead and start your model, set the throttle trim high enough to keep the clutch engaged, hover it, fly it around and get comfortable. Get a feeling for which way the wind is blowing. Land the model on your target directly into the wind and, before it spools down, flip the throttle hold switch while it is still light on the skids. Watch the tail. If the nose goes right ( it should ), either adjust for it if you're lucky enough to have a radio with digital trims, or just be ready for it to happen when you flip the switch. It's not going to be a problem, I promise. If you set it up as I described above, when you flipped the switch, the only thing that should have changed is the tail trim, but be ready anyway.

If that went well, go ahead and hover it about 6 inches above the ground. When it's still, flip the throttle hold switch and let it settle gently to the ground, adding pitch as it descends. This will give you an idea of how much inertia your blades have. Remember with that throttle trim up high, you'll have a little more time. Go ahead and play with the throttle trim to get an idea of how it acts without it. Make sure to set it back to high idle before you try the real thing.

Where you flip the switch on your first autos is very important. If you are too far away, you'll come up short, or worse yet be so far away you won't be able to see what the model is doing. If you're too close, you'll overshoot your target and be landing too far away. So, pick a spot in the air that's about 75 - 100 feet high and at a 45 degree angle up. You could set a cone about 80 feet downwind and use that as a marker. The altitude isn't as important as the angle, but it should be at least 75 feet high. Shoot a couple powered approaches, starting your descent above and outside of that spot. Practice until you're satisfied that you can descend into the wind and pass through the spot with the collective around -3. The model should be level or just a tiny bit nose down.

You are ready

Better refuel, because once you start this you aren't going to want to quit. Takeoff and climbout however you're comfortable. Get the model lined up outside and above the spot. Get a little forward speed going and make your approach to the spot. At this point your collective should be at about -3 and the model should be level, or just a tiny bit nosedown, just like you practiced. When you get to the spot, flip the throttle hold switch. At this point, if you have followed instructions, all you have to worry about is flying the model. Keep it level until it's about 20 feet high, then ever so gently, start to raise the nose a little bit. This does two things. It slows the forward speed and increases the blade speed. Do not raise the nose too much. The last thing you want, is for the model to stop forward motion and possibly start drifting backwards. Just keep it coming. At this point you have lots of blade speed and are going pretty slow. When you get to eyelevel. Raise the nose just a little more, but be ready to level the machine as it gets to waist level. At waist level, if your forward motion has stopped, simply level the machine and land it. If not, level it and raise the collective a little, to about zero. As it approaches the ground, feed in a little more collective and let it slide onto the ground gently. Once you are on the ground you can either keep adding collective and keep sliding, or reduce the collective to full down and stop. The things to consider are how smooth the ground is and how fast are my blades going. If you have good blade speed, it doesn't matter. If your blade speed is gone, you better stop. Note that you were on the ground and the pitch was just above zero....hmmmmmmm. This isn't so hard. Now do a few thousand more. Just remember to level the machine before you land, regardless of everything else. If you land tail down, I'll guarantee you a boom strike. The main thing is, don't be afraid to slide a little. That's how the real ones do it.

This is going to cost me!

Contrary to what you might think, learning to auto will save you tons of money. Yes, you might screw up a few times and have an occasional boom strike, but let me tell you, it's a lot better than having your engine quit going downwind and not knowing what to do! And really, there isn't much reason to have a boom strike unless you just don't level the machine before you land. Even with minimal blade speed you can slide it on, even downwind. Just hope for smooth ground in an emergency.

One time in Houston, I was flying a Nexus Deluxe. I was into doing stupid things at that time and I rolled it inverted out of a two foot hover. Much to my dismay, I hadn't flipped the idle up switch. The little Nexus just settled to the ground because I was at full down on the collective, which put my throttle at idle. It was my first inverted full down auto :-) I walked up to it and it was still idling. I picked it up and set it back on it's skids. Nothing was wrong with it ! Thinking I was living a charmed life, I took off and proceeded to fly it around until it ran out of gas, of course I was going downwind. I did the sliding auto and everything was going good, until a gopher hole jumped up and caught one of my skids It balled up pretty good. The moral of this story...landing on your head can be painless. Running out of gas going downwind can be painless. However, a gopher hole can ruin your day.

Next ...

Copyright © 2010 Ron Lund, RONLUND.COM and Ron's Heliproz South All rights reserved

Valid XHTML 1.0 Transitional