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Losing Airspeed


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Here's a stupid question for all you DaVinci's out there: why do I lose airspeed in a turn? I'll get into a 30 degree bank and do a standard turn starting at 70 kts, but by the time I level out, I'm doing 30 kts.

 

Nick mentioned that I was pulling back on the stick in the turn. I didn't notice it. I guess it's a habit from my airplane days. The only thing I can think of that'll cause me to pull back is because I have my arm in my lap and I'm pulling back as I push left. Like I said, I don't notice any backward movement but I wonder if ya'll might have any other ideas on why this anomaly occurs.

 

By the way, I gotta tell ya. Last week after a day of hovering heaven, we flew back to the ramp and landed. After shutting down and walking away, Mike looked and noticed that the hook was dead center of the line and the bird was perfectly straight on the line. Dang I wish I had a camera. He was telling me that this was probably the only time that'll ever happen and that no matter how hard I try, I'll never be able to get it lined up like that ever again. He bet me a beer.

 

We also settled with power.

 

You know, the more I fly, the more work sucks.

 

Later.

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Very common problem. If you look in Rotorcraft Handbook in 'Turns' I believe it says you may need forward cyclic to maintain airspeed.

So if you are pulling back (which is easy to do without knowing) you will lose airspeed and it will come down pretty quick.

If your an airplane pilot I would suggest keeping you eyes on your pedal movement, I bet your are turning with the pedals too.

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Here's a stupid question for all you DaVinci's out there: why do I lose airspeed in a turn? I'll get into a 30 degree bank and do a standard turn starting at 70 kts, but by the time I level out, I'm doing 30 kts.
That's a bit more than a standard turn - at 70KT, it takes around a 12-degree bank to get a standard-rate turn (aka the "2-minute" turn). 30 degrees is a steep turn - when making a steep turn, you will have to slow down roughly 10KT to maintain altitude if you leave your power setting alone.

 

As far as why you are doing 30KT? Well, like Sebas said, you are probably adding aft cyclic to the mix. You might also be letting the collective fall a bit, which would lead you to slow down in order to maintain altitude.

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Nick mentioned that I was pulling back on the stick in the turn. I didn't notice it. I guess it's a habit from my airplane days.

 

 

Me too... Used to do the same thing since I'm an airplane guy... same principle as losing lift in a turn with an airplane... the fix is to pull back on the stick...

 

It will go away... mine did!

 

Gunner

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You need to use some pedal in turns, similar to an airplane. The difference is that you can take it out when the turn is established. With no pedal, there is some adverse yaw when entering the turn. The magnitude is different with different models, and on small helicopters it's rather small, so the standard teaching is to not use any pedal, because it's easier to teach that than to teach pedal input followed shortly by a different input back to where you were. Check the trim ball closely when you start a turn, if you have one. It will move out of center, then back in. In an S76, it goes more than half a ball out, and stays there for some time. You really need to use pedal just like in a fixed-wing to enter a turn. If not, you're in uncoordinated flight, and will lose airspeed/altitude eventually. What initially happens in most models as you enter a turn is that the nose pitches up slightly, you get out of trim, and thus you lose airspeed and start to gain a little altitude, but the altitude gain is somewhat offset by the out of trim condition, and you airspeed loss outweighs altitude gain. What I do is use some pedal into the turn and put in some forward cyclic at the same time. Doing a lot of turns under the hood or in IMC does wonders for your ability to do precise turns. We have to do steep turns under the hood for every checkride, every 6 months, and this teaches you to anticipate what will happen, otherwise you won't be able to maintain the aircraft within 50 feet of the desired altitude.

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Witch- I'm sure at some point in the past I had that same issue.

 

So, I applied some complex aeronautical formulas and came up with the answer. I now take a quick look at my airspeed indicator now and then to keep my airspeed the same. I know its revolutionary, I really didn't want to express it here where all could see my secrets...but oh well. ( yes, I am as much a smart a** as you sometimes)

 

Good job on the landing, I always try to get skids down perfectly aligned and gentle enough that it feels like sitting down in a chair...rather than skidding across the pavement!

 

See ya. Goldy

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Thank you for your insights and secrets Goldy, as a newbie I need all the help I can get. Any other gemsyou could share! (Not being sarcastic either)

 

 

 

Sorry Roger- I just was humored by all the complex theories...let's talk about how important it is for those of us that fly low energy, single engine pistons, to maintain your airspeed at low altitudes rather than try and conjecture the fine points of theory......just my thought.

 

Witch- here's some real advice. Never let your airspeed fall below 60 KIAS, and if you do, make sure its at an altitude your comfortable falling from. Get used to doing a quick scan of your control panel, that includes the gauges, warning lights, oil pressure, carb temp and airspeed....

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Witch- here's some real advice. Never let your airspeed fall below 60 KIAS, and if you do, make sure its at an altitude your comfortable falling from. Get used to doing a quick scan of your control panel, that includes the gauges, warning lights, oil pressure, carb temp and airspeed....

I never take my eyes off the panel, even for takeoffs or landings.

 

Really, I started noticing that I was pulling back on the stick when turning. It figures it'd be an old airplane habit. Anyhow, I did a few turns where I pushed the stick forward and although the VSI went down a little, airspeed dropped only a couple of knots. I guess I just need to develop a technique to keep doing that.

 

Also did a couple of autos-hover autos too-and I blew them big time. Couldn't keep the rotor speed in the green. Up-down-up-down, it was a mess. Looks like I picked the wrong day to quit amphetamines.

 

Later

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I never take my eyes off the panel, even for takeoffs or landings.

 

Really, I started noticing that I was pulling back on the stick when turning. It figures it'd be an old airplane habit. Anyhow, I did a few turns where I pushed the stick forward and although the VSI went down a little, airspeed dropped only a couple of knots. I guess I just need to develop a technique to keep doing that.

 

Also did a couple of autos-hover autos too-and I blew them big time. Couldn't keep the rotor speed in the green. Up-down-up-down, it was a mess. Looks like I picked the wrong day to quit amphetamines.

 

Later

 

 

Seriously Witch, airspeed is the key to a great auto in a R22. Take it right to 65KIAS or so, and just a bit of up collective to hold it in the bottom/middle of the green rotor rpm. Once the airspeed is right, the RPM will stay constant and you won't chase it at all. A couple of times and you'll get the hang of it...I hate to say its easy because I have blown my share of them...but not chasing airspeed around really helps. Cant help you with the amps....have you tried sniffing glue instead?

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I never take my eyes off the panel, even for takeoffs or landings.
Here's something really important (aw heck lets call it critical), and the sooner you learn and believe it, the sooner you will transition from helicopter operator to helicopter pilot.

 

Flying a helicopter VFR is an eyes outside process, and the most useless instrument for controlling a helicopter is the airspeed indicator. The airpeed indicator is strictly a performance instrument - it (combined with the altimeter) will tell you if you are holding the proper aircraft attitude and the right amount of power. The only way to hold the right attitude is to keep your eyes outside. If you want to learn to hold a consistant airspeed, fly an entire lesson with the airspeed indicator covered. Heck, fly for a WEEK with the instrument covered.

 

Look to the attitude, check the results with the airspeed. Your CFI can help - if (s)he notes you are slow or fast, they should point to the ATTITUDE, not the airspeed indicator.

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I have to admit that many, many years ago I took off in an AS350D in the wintertime. There had been freezing rain forecast, although it never got close to freezing. Maintenance plugged the intake and exhaust openings of all the aircraft, and covered the pitot tubes of all the aircraft during the night. When I preflighted in the dark, I didn't notice that my pitot tube (way down underneath the belly, in the dark right above the standing water) had a small clear plastic bag covering it, held in place by a rubber band. No streamer, no nothing. I loaded up a cabin full of groceries and headed offshore. I had probably gone 10 miles or more before I noticed that my airspeed was reading zero. I just continued to the platform, and told the customers I was going to shut down to unload the groceries, and while they were unloading, I checked the pitot tube and removed the bag. Airspeed isn't at all critical in a small helicopter. If you have some experience, you can fly on power and attitude, and the approach is done using apparent rate of closure, not airspeed. I never worried about airspeed on approach in a small helicopter, and I don't worry about it that much in larger ones. In IMC, it's a different story, but we're not talking about that here.

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Hey Goldy, would you happen to have a valium or two I could borrow? Actually I did a great auto on the checkride and a couple of good ones last week. I just blew both of them yesterday. I totally suck. I taxied down the abandoned, and with all the dry grass on it the bird was acting like a leafblower. Call me Weedwhacker. But back to the auto, I was just having a bad moment. If this were an actual auto I think I would have at least bent the skids.

 

Fling, I was kidding about the "I never take my eyes off the panel, even for takeoffs or landings" bit. I have a tendancy to do that. I do fly outside the bird, especially while standing on the skid. I did an excellent TO and landing to a spot next to the VORTAC. Slope landings on the other hand... Please-and this goes for the rest of ya'll-don't take me too seriously. If it sounds rediculous, it probably is and meant to be funny. I come across as a smarta$$ sometimes. I don't mean to be, I just do. Sorry for the confusion.

 

Howabout a Fresca?

 

Later.

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If anyone was looking for a Da Vinci-esque answer: You will loose airspeed in a turn if you don't add power the same way Fixed wings do - or you're car for that matter. Da Vinci didn't really have this one covered but Newton's First Law of motion does. Objects at rest tend to stay at rest and Objects in motion tend stay in motion with the same speed and direction. It takes more energy to turn because of a centripetal (towards the center) acceleration; and you can feel this acceleration expressed as extra gravity in sharper turns. The end-game is that you will need to add collective and forward cyclic to maintain airspeed in a turn.

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