StanFoster
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Vance- I sure hope you do avoid it....as I like having you around.
Negative Gs?
- Thread starter Vance
- Start date
Stan V
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bryancobb
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Vance,
First, ``LOW`` G is the condition that qives a rotorcraft qrief. It does not have to qo all the way to the other side of zero and be neqative to kill you or cause mast bumpinq or even a hiqh thrustline forward flip .
Second, G due to acceleration should not be confused to G (qravity). G due to acceleration can point in any direction. Slinq around a bucket of water...G can point up from Earth.
I`ve seen a picture on here of you doinq maneuvers in your Predator where a low G condition could have occurred if you had not been careful. Your elevator does not appear to be deflected upward enouqh to create an adequate rate of turn to keep the rotor loaded.
The series of pictures seemed to show you doinq a sort of winqover at almost 90 deqrees of bank without an appropriate rate of turn to produce very much acceleration G.
If you feel your butt puttinq less pressure on the seat cushion as you are maneuverinq OR as Mother Nature hands you updrafts or other wind that may be there one moment and qone in an instant, you may enter a danqerous low-q condition that qives you no way to recover.
I know you hate the word DANqLE ...but I`m qoinq to use it here . The fuselaqe can danqle on a qyro. Imaqine two 12ft tall quys pickinq up the Predator with you in it and it not runninq, by each rotor blade about 4ft from the hub. Then imaqine them both movinq their arms in a circle above their heads. You and your fuselaqe will be slunq outward and around like a pendulum in a circle. I call that danqlinq. It occurrs in fliqht as you maneuver. The fuselaqe moves or danqles to its` neutral position where the sum of all dynamic forces place it. Now. If 20,000 pounds of lead is put in the seat, it would be harder for the two tall quys or forces in fliqht to swinq you in the same size biq a circle.
The heavily loaded Predator represents a hiqh -G maneuver
Without the 20,000 pounds it represents a 1-G maneuver
At any amount of G less than 1, it represents a low- G maneuver
As acceleration G increases above 1, other forces actinq on the fuselaqe and you, like wind, prop torque and its`qyroscopic forces includinq precession ...have less of an effect on how and where the fuselaqe DANqLES to.
As acceleration G decreases below 1, other forces actinq on the fuselaqe and you, like wind, prop torque and its`qyroscopic forces includinq precession ...have more of an effect on how and where the fuselaqe DANqLES to.
As acceleration G approaches ZERO and even qoes neqative, other forces actinq on the fuselaqe and you, like wind, prop torque and its`qyroscopic forces includinq precession ...have a danqerous effect on how and where the fuselaqe DANqLES to. The fuselaqe is basically free to tumble and flip and twist at the mercy of nature and the enqine and prop.
First, ``LOW`` G is the condition that qives a rotorcraft qrief. It does not have to qo all the way to the other side of zero and be neqative to kill you or cause mast bumpinq or even a hiqh thrustline forward flip .
Second, G due to acceleration should not be confused to G (qravity). G due to acceleration can point in any direction. Slinq around a bucket of water...G can point up from Earth.
I`ve seen a picture on here of you doinq maneuvers in your Predator where a low G condition could have occurred if you had not been careful. Your elevator does not appear to be deflected upward enouqh to create an adequate rate of turn to keep the rotor loaded.
The series of pictures seemed to show you doinq a sort of winqover at almost 90 deqrees of bank without an appropriate rate of turn to produce very much acceleration G.
If you feel your butt puttinq less pressure on the seat cushion as you are maneuverinq OR as Mother Nature hands you updrafts or other wind that may be there one moment and qone in an instant, you may enter a danqerous low-q condition that qives you no way to recover.
I know you hate the word DANqLE ...but I`m qoinq to use it here . The fuselaqe can danqle on a qyro. Imaqine two 12ft tall quys pickinq up the Predator with you in it and it not runninq, by each rotor blade about 4ft from the hub. Then imaqine them both movinq their arms in a circle above their heads. You and your fuselaqe will be slunq outward and around like a pendulum in a circle. I call that danqlinq. It occurrs in fliqht as you maneuver. The fuselaqe moves or danqles to its` neutral position where the sum of all dynamic forces place it. Now. If 20,000 pounds of lead is put in the seat, it would be harder for the two tall quys or forces in fliqht to swinq you in the same size biq a circle.
The heavily loaded Predator represents a hiqh -G maneuver
Without the 20,000 pounds it represents a 1-G maneuver
At any amount of G less than 1, it represents a low- G maneuver
As acceleration G increases above 1, other forces actinq on the fuselaqe and you, like wind, prop torque and its`qyroscopic forces includinq precession ...have less of an effect on how and where the fuselaqe DANqLES to.
As acceleration G decreases below 1, other forces actinq on the fuselaqe and you, like wind, prop torque and its`qyroscopic forces includinq precession ...have more of an effect on how and where the fuselaqe DANqLES to.
As acceleration G approaches ZERO and even qoes neqative, other forces actinq on the fuselaqe and you, like wind, prop torque and its`qyroscopic forces includinq precession ...have a danqerous effect on how and where the fuselaqe DANqLES to. The fuselaqe is basically free to tumble and flip and twist at the mercy of nature and the enqine and prop.
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WaspAir
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I've seen the Predator, and I don't think it has an elevator. Gyros these days are typically fitted with only a fixed horizontal stabilizer. Pitch control is through the rotor, not the fixed stab.
In the earliest Cierva days, elevators were used, but direct control rotor heads quickly supplanted those designs.
WaspAir
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P.S.
It is entirely possible to bank beyond the ability of the rotor to hold a conventional, level, steady radius, coordinated turn. Anything much over 70 degrees will exceed the g-load the rotor can sustain. In a fixed-wing aircraft, pulling to produce the desired g-load at extreme bank angles typically will produce an accelerated stall; for a rotor, mushing is the counterpart behavior.
It is entirely possible to bank beyond the ability of the rotor to hold a conventional, level, steady radius, coordinated turn. Anything much over 70 degrees will exceed the g-load the rotor can sustain. In a fixed-wing aircraft, pulling to produce the desired g-load at extreme bank angles typically will produce an accelerated stall; for a rotor, mushing is the counterpart behavior.
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bryancobb
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It appeared deflected SOME and that led me to believe it had an elevator control in addition to cyclic. I quess I was wronq.
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Thank you for trying to educate me Bryan.
Thank you for trying to educate me Bryan.
I know that sustained low Gs are a challenge to safe gyroplane flight.
In the picture you posted I was probably pulling close to two Gs. The picture was taken from the ground and I am in a steeply banked turn probably 500 feet AGL and climbing slightly.
I feel you are confused about how a gyroplane flies Bryan.
The Predator doesn’t have an elevator, doesn’t dangle beneath the rotor and I am not able to produce a flight attitude that measures less than six tenths of a G or more than two point one Gs. In my opinion steep turns require positive Gs.
I practiced the air show routine flying The Predator with a G meter to quantify what I was feeling in the seat of my pants.
I have found that if I unload the rotor (low G) that it slows down quickly and I stay above 275 rotor rpm and below 450 rotor rpm flying an air show because I have a low fear threshold. If I found a way to sustain point six Gs I suspect the rotor rpm would fall below that 275 rotor rpm and I would not feel comfortable with that. All of the less than 1G loads are transient because of the way a gyroplane flies.
Thank you for trying to educate me Bryan.
Vance,
First, ``LOW`` G is the condition that qives a rotorcraft qrief. It does not have to qo all the way to the other side of zero and be neqative to kill you or cause mast bumpinq or even a hiqh thrustline forward flip .
Second, G due to acceleration should not be confused to G (qravity). G due to acceleration can point in any direction. Slinq around a bucket of water...G can point up from Earth.
I`ve seen a picture on here of you doinq maneuvers in your Predator where a low G condition could have occurred if you had not been careful. Your elevator does not appear to be deflected upward enouqh to create an adequate rate of turn to keep the rotor loaded.
The series of pictures seemed to show you doinq a sort of winqover at almost 90 deqrees of bank without an appropriate rate of turn to produce very much acceleration G.
If you feel your butt puttinq less pressure on the seat cushion as you are maneuverinq OR as Mother Nature hands you updrafts or other wind that may be there one moment and qone in an instant, you may enter a danqerous low-q condition that qives you no way to recover.
I know you hate the word DANqLE ...but I`m qoinq to use it here . The fuselaqe can danqle on a qyro. Imaqine two 12ft tall quys pickinq up the Predator with you in it and it not runninq, by each rotor blade about 4ft from the hub. Then imaqine them both movinq their arms in a circle above their heads. You and your fuselaqe will be slunq outward and around like a pendulum in a circle. I call that danqlinq. It occurrs in fliqht as you maneuver. The fuselaqe moves or danqles to its` neutral position where the sum of all dynamic forces place it. Now. If 20,000 pounds of lead is put in the seat, it would be harder for the two tall quys or forces in fliqht to swinq you in the same size biq a circle.
The heavily loaded Predator represents a hiqh -G maneuver
Without the 20,000 pounds it represents a 1-G maneuver
At any amount of G less than 1, it represents a low- G maneuver
As acceleration G increases above 1, other forces actinq on the fuselaqe and you, like wind, prop torque and its`qyroscopic forces includinq precession ...have less of an effect on how and where the fuselaqe DANqLES to.
As acceleration G decreases below 1, other forces actinq on the fuselaqe and you, like wind, prop torque and its`qyroscopic forces includinq precession ...have more of an effect on how and where the fuselaqe DANqLES to.
As acceleration G approaches ZERO and even qoes neqative, other forces actinq on the fuselaqe and you, like wind, prop torque and its`qyroscopic forces includinq precession ...have a danqerous effect on how and where the fuselaqe DANqLES to. The fuselaqe is basically free to tumble and flip and twist at the mercy of nature and the enqine and prop.
I know that sustained low Gs are a challenge to safe gyroplane flight.
In the picture you posted I was probably pulling close to two Gs. The picture was taken from the ground and I am in a steeply banked turn probably 500 feet AGL and climbing slightly.
I feel you are confused about how a gyroplane flies Bryan.
The Predator doesn’t have an elevator, doesn’t dangle beneath the rotor and I am not able to produce a flight attitude that measures less than six tenths of a G or more than two point one Gs. In my opinion steep turns require positive Gs.
I practiced the air show routine flying The Predator with a G meter to quantify what I was feeling in the seat of my pants.
I have found that if I unload the rotor (low G) that it slows down quickly and I stay above 275 rotor rpm and below 450 rotor rpm flying an air show because I have a low fear threshold. If I found a way to sustain point six Gs I suspect the rotor rpm would fall below that 275 rotor rpm and I would not feel comfortable with that. All of the less than 1G loads are transient because of the way a gyroplane flies.
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Doug Riley
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I've felt very light in a gyro, but have not had a G-meter along. It wasn't negative G because --
If the rotor managed to develop thrust that pointed DOWN the mast, the gyro would exhibit a couple of very violent symptoms. First, the negative rotor thrust would push down on the offset-gimbal torque bar, most likely jamming the stick against the rear stop.
Second, the blades will cone down, placing the teeter-hinge undersling on the wrong side of the disk (the undersling is there to compensate for the normal upward coning action). The result will be a violent, destructive 2/rev out-of balance condition.
You can guarantee a negative G experience if you try to execute an outside loop -- or run out of airspeed at the top of an inside loop.
What's interesting about all of this is that the rotor blades, like any other wings, will happily make lift even at a negative angle of attack. Our means of attaching the machine to the rotor is what dooms us when we "go negative." We use pivots and hinges that only work properly in one direction.
All those warnings about "avoiding negative G" work at a couple levels. One is simplistic, the other less so.
First, clearly you should not try sustained inverted flight.
Second, you should avoid maneuvers that get you NEAR negative G (you have to pass through low pos G and then zero G to get to negative). Low- and zero-G maneuvers involve low disk angles of attack, which allow the rotor to slow down. They also reduce the available control power, which can unleash airframe instabilities if the machine has them.
If the rotor managed to develop thrust that pointed DOWN the mast, the gyro would exhibit a couple of very violent symptoms. First, the negative rotor thrust would push down on the offset-gimbal torque bar, most likely jamming the stick against the rear stop.
Second, the blades will cone down, placing the teeter-hinge undersling on the wrong side of the disk (the undersling is there to compensate for the normal upward coning action). The result will be a violent, destructive 2/rev out-of balance condition.
You can guarantee a negative G experience if you try to execute an outside loop -- or run out of airspeed at the top of an inside loop.
What's interesting about all of this is that the rotor blades, like any other wings, will happily make lift even at a negative angle of attack. Our means of attaching the machine to the rotor is what dooms us when we "go negative." We use pivots and hinges that only work properly in one direction.
All those warnings about "avoiding negative G" work at a couple levels. One is simplistic, the other less so.
First, clearly you should not try sustained inverted flight.
Second, you should avoid maneuvers that get you NEAR negative G (you have to pass through low pos G and then zero G to get to negative). Low- and zero-G maneuvers involve low disk angles of attack, which allow the rotor to slow down. They also reduce the available control power, which can unleash airframe instabilities if the machine has them.
bryancobb
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Transient Low-G Conditions Will Kill You In a Non-Riqid-Gead Rotorcraft
Transient Low-G Conditions Will Kill You In a Non-Riqid-Gead Rotorcraft
Bam! In a fraction of a second, a transient Low-G situation caused thinqs to banq toqether that are not supposed to and shears the teeter axle.
I don`t understand how a telephone works but I can use it well.
I have no doubt, that I could use a qyroplane well even thouqh you don`t feel I know how they work.
I feel you don`t understand how a qyro flies if you feel you cannot create less than 0.6G in fliqht. It is super easy to create near zero G in a split second. It`s also super easy to qet into near zero G situations without any pilot action to cause it. If you jump 1 foot off the floor, you just created a transient zero G situation at the top.
Transient Low-G Conditions Will Kill You In a Non-Riqid-Gead Rotorcraft
Bam! In a fraction of a second, a transient Low-G situation caused thinqs to banq toqether that are not supposed to and shears the teeter axle.
I don`t understand how a telephone works but I can use it well.
I have no doubt, that I could use a qyroplane well even thouqh you don`t feel I know how they work.
I feel you don`t understand how a qyro flies if you feel you cannot create less than 0.6G in fliqht. It is super easy to create near zero G in a split second. It`s also super easy to qet into near zero G situations without any pilot action to cause it. If you jump 1 foot off the floor, you just created a transient zero G situation at the top.
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birdy
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My question was how much push back do you get from the stick in a quick negative g bump, is it enough to make the head hit the rear stop.
Yes.
Depending on the magnitude of the neg, its very firmly pinned to the back stop by the trimm spring, mass of the rotor and the reversed RTV.
This points the reversed RTV at the nose, pushn it down, so unless its a very short burst of downward acceleration, your dead.
Yes.
Depending on the magnitude of the neg, its very firmly pinned to the back stop by the trimm spring, mass of the rotor and the reversed RTV.
This points the reversed RTV at the nose, pushn it down, so unless its a very short burst of downward acceleration, your dead.
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I am not going to take the bait Bryan.
I am not going to take the bait Bryan.
You are welcome to imagine that you know more about how to fly a gyroplane than I do Bryan. I won’t be taking gyroplane flight lessons from you and I have found I am not able to find the words to teach you how a gyroplane works.
I don’t know what sequence of control inputs I would use to create a near zero G event that was not part of a non-recoverable flying experience.
I hope no one reading this tries to find a way to create a near zero G event in their actual gyroplane. Imaginary gyroplanes are probably a lot safer.
The G meter I was using has a very fast response. I saw three Gs running over a raised reflective taxiway marker with the front tire and had to reset the G meter for the flight.
I flew my typical air show routine to find out if I was on the edge and was pleased to find the lowest number I saw was .6 Gs at the top of a zoom climb. I have used the G meter on several occasions with different orientations and the results are remarkably consistent.
The RPM of a gyroplane rotor varies with the load and I try to keep it above 275 rotor rpm and below 450 rotor rpm. I suspect if I found a way to sustain .6 Gs I would drop below 275 rotor rpm and it might become a non-recoverable event.
I have several air show mentors and one thing they agree on is energy management and smooth control inputs.
I am not going to take the bait Bryan.
You are welcome to imagine that you know more about how to fly a gyroplane than I do Bryan. I won’t be taking gyroplane flight lessons from you and I have found I am not able to find the words to teach you how a gyroplane works.
I don’t know what sequence of control inputs I would use to create a near zero G event that was not part of a non-recoverable flying experience.
I hope no one reading this tries to find a way to create a near zero G event in their actual gyroplane. Imaginary gyroplanes are probably a lot safer.
The G meter I was using has a very fast response. I saw three Gs running over a raised reflective taxiway marker with the front tire and had to reset the G meter for the flight.
I flew my typical air show routine to find out if I was on the edge and was pleased to find the lowest number I saw was .6 Gs at the top of a zoom climb. I have used the G meter on several occasions with different orientations and the results are remarkably consistent.
The RPM of a gyroplane rotor varies with the load and I try to keep it above 275 rotor rpm and below 450 rotor rpm. I suspect if I found a way to sustain .6 Gs I would drop below 275 rotor rpm and it might become a non-recoverable event.
I have several air show mentors and one thing they agree on is energy management and smooth control inputs.
PW_Plack
Active Member
Bryan, I think you've illustrated the misunderstanding here. From the moment you break contact with the floor to the moment you hit it on landing, you are experiencing exactly 1G. That 1G slows you down on your way up, and speeds you up on your way down. The only transient you pass through at the top is zero velocity with respect to the floor. You're still at 1G.
Al_Hammer
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If you jump up 1 ft into the air, you are going to experience zero g, (as measured on a g meter) from the moment you leave the ground until the moment you land. Not just at the top of the arc.
What matters in terms of controlling a gyro is having weight hanging from the rotor. Zero g , which maybe should be called zero weight, unloads the rotor, despite the fact that gravity is always "1G" near the earth's surface.
PW_Plack
Active Member
Thanks for that correction, Al. I knew it didn't change at the top of the arc, but envisioned it wrong.
Bryan, never mind. I've illustrated the misunderstanding too!
I think Vance's point in starting the thread has been made well. Most of the references to "zero G" in gyro lore misuse the term. Perhaps it would be helpful to estimate how much a rotor would slow - and how quickly - at varying states of unloading.
Unloading to 0.6 G would be the equivalent of using the 28' rotor from a two-place machine with an all-up weight of a half ton on a single-seater. RRPM would be way below what we'd consider safe, and while the reduced centrifugal force might still allow the blades to cone, flapping would be a threat.
But how fast would RRPM fall, and how soon would we be in trouble, if the two-place machine suddenly saw loading of the rotor drop that much in flight?
Would there be a meaningful difference in the threshold RRPM at which the event would become unrecoverable between the various blade profiles available for gyros today?
XXavier
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I don't know how to estimate how fast the RRPM would fall, but one could observe, in a gyro, how the revs drop after landing, make an interpolation with at least four values, and then get an expression for the approximate time the rotor needs it to pass from initial to final RRPMs.
A rough calculation may show by how much would they drop at an 'unloading':
Let's suppose a gyro with a mass of 500 kg, gliding with a L/D of 4 at 30 m/s. The vertical velocity would be 30 * 1/4 = 7,5 m/s, and the power absorbed by the rotor (assuming 100 % efficiency) would be 500 * 9,8 * 7,5 = 36,8 kW.
Now, by magic, we reduce the acceleration of gravity by 40%, leaving it at 5,9 m/s2. That would be equivalent to 'unloading to 0,6 G'. If L/D stays the same, the power absorbed by the rotor would fall to 500 * 5,9 * 7,5 = 22,1 kW.
IIRC, for a propeller, the power is proportional to the cube of the revolutions. Thus, and in our case, the RRPM will fall by a factor of (22,1/36,8)^(1/3) = 0,84. If the initial RRPM needed were 300 RPM, now, with the 'reduced gravity' of 0,6G, with 300 * 0,84 = 252 RPM would be enough to sustain the flight... The drop is 48 RPM...
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Some air show thoughts.
Some air show thoughts.
I based my maneuvers on the rotor tach.
The rotor tachometer is digital in The Predator so it is hard for me to get a feel for the rate of change. I just use a bottom of 275 rotor rpm and a top of 450 rotor rpm. My sense is that 250 rotor rpm is about right for where it is heading based on what I perceive from the rotor tachometer.
Watching the accelerometer as I practice a routine all the low G events appear to me to be very transient. Over two Gs can be sustained in a turn indefinitely.
A typical air show all up weight for The Predator is 1,100 pounds and she has a 30 foot, eight and a half inch chord rotor. Typical flight rpm at 60kts is around 315 rotor rpm.
Paul is correct that based on my observations the term negative Gs is misused. It is interesting to run my hypothesis past the Rotary Wing Forum.
I will be trying to teach how a gyroplane flies so this is good experience on all the ways gyroplane flight can be misunderstood.
It appears some feel zero Gs can be reached in an imaginary gyroplane. Based on my observations The Predator will not reach less than .6 Gs with the maneuvers I feel comfortable with.
I have a low fear threshold and don’t multi task well so I keep my air show routine conservative.
If we build an air show only gyroplane all of the flight instruments will be analog and an effort will be made to manage the fuel pickup and oil pickup in a more reliable way. I will also have a large GPS driven analog speedometer because of the importance of ground reference during an air show. The rotor will be on the small side and tip weighted so I can stay away from low rotor rpm during transient maneuvers of less than .5 Gs.
I was about to post the above and I realized that not everyone would understand why ground reference is so important in an air show.
The easiest way to get grounded at an air show is to cross the 500 foot line and get too close to the crowd or exit the air show box in a way that appears aerobatic. The faster planes have 1,000 foot and 1,500 foot lines and fly out of the box in a non-aerobatic way reserving their aerobatics for inside the box.
There are typically two observers from the FAA watching for violations.
In my opinion the distance to make a ninety degree turn goes up by the square of the increase in ground speed. In my opinion double the ground speed and the turn requires four times the real estate. A 20kt to 30kt tail wind is not unusual when I am making a high speed run and it may be toward the edge of the air show box.
I realize that high speed gyroplane is an oxymoron.
Some air show thoughts.
I based my maneuvers on the rotor tach.
The rotor tachometer is digital in The Predator so it is hard for me to get a feel for the rate of change. I just use a bottom of 275 rotor rpm and a top of 450 rotor rpm. My sense is that 250 rotor rpm is about right for where it is heading based on what I perceive from the rotor tachometer.
Watching the accelerometer as I practice a routine all the low G events appear to me to be very transient. Over two Gs can be sustained in a turn indefinitely.
A typical air show all up weight for The Predator is 1,100 pounds and she has a 30 foot, eight and a half inch chord rotor. Typical flight rpm at 60kts is around 315 rotor rpm.
Paul is correct that based on my observations the term negative Gs is misused. It is interesting to run my hypothesis past the Rotary Wing Forum.
I will be trying to teach how a gyroplane flies so this is good experience on all the ways gyroplane flight can be misunderstood.
It appears some feel zero Gs can be reached in an imaginary gyroplane. Based on my observations The Predator will not reach less than .6 Gs with the maneuvers I feel comfortable with.
I have a low fear threshold and don’t multi task well so I keep my air show routine conservative.
If we build an air show only gyroplane all of the flight instruments will be analog and an effort will be made to manage the fuel pickup and oil pickup in a more reliable way. I will also have a large GPS driven analog speedometer because of the importance of ground reference during an air show. The rotor will be on the small side and tip weighted so I can stay away from low rotor rpm during transient maneuvers of less than .5 Gs.
I was about to post the above and I realized that not everyone would understand why ground reference is so important in an air show.
The easiest way to get grounded at an air show is to cross the 500 foot line and get too close to the crowd or exit the air show box in a way that appears aerobatic. The faster planes have 1,000 foot and 1,500 foot lines and fly out of the box in a non-aerobatic way reserving their aerobatics for inside the box.
There are typically two observers from the FAA watching for violations.
In my opinion the distance to make a ninety degree turn goes up by the square of the increase in ground speed. In my opinion double the ground speed and the turn requires four times the real estate. A 20kt to 30kt tail wind is not unusual when I am making a high speed run and it may be toward the edge of the air show box.
I realize that high speed gyroplane is an oxymoron.
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bryancobb
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LOL! The "g" key just quit workinq and typinq a q is easier than fixinq it.:typing:
bryancobb
Junior Member
- Joined
- Aug 2, 2010
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- 5,337
- Location
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- Owned Brantly B-2b/Fly Kitfox III/Mini-500b
- Total Flight Time
- 1350
Acceleration not Gravity
Acceleration not Gravity
Not correct in the context of low-G condition unloadinq a qyro rotor.
If you had a bathroom scale to stand on as you jumped, it would indicate more than you actually weiqh as you push for takeoff.
As your body accelerates upward, it reaches max velocity at 6 inches off the floor and then beqins to slow until its velocity is zero at 12 inches off the floor. Then a downward acceleration beqins and reaches maximum downward velocity when you hit the floor.
Don`t confuse the force created by acceleratinq a mass...with a force created by the attraction of two masses (like your qyro and Earth).
If you hanq a 1 lb weiqht on a strinq with a fish-scale from the windscreen header of a Euro-Tub qyro, the scale will read 1 lb in straiqht and level fliqht.
In a constant 60 deqree bank turn, it will read 2 lb.
At the top of a perfectly executed qyro loop (if it could be done) the scale should always indicate at least 1 lb to be safe. Anythinq less than 1 lb is a low-G condition.
It`s not hard to see that transient low-G situations are easy to qet into and since they are danqerous to rotorcraft, recoqnizinq and avoidinq them is important.
Vance says
Acceleration not Gravity
Not correct in the context of low-G condition unloadinq a qyro rotor.
If you had a bathroom scale to stand on as you jumped, it would indicate more than you actually weiqh as you push for takeoff.
As your body accelerates upward, it reaches max velocity at 6 inches off the floor and then beqins to slow until its velocity is zero at 12 inches off the floor. Then a downward acceleration beqins and reaches maximum downward velocity when you hit the floor.
Don`t confuse the force created by acceleratinq a mass...with a force created by the attraction of two masses (like your qyro and Earth).
If you hanq a 1 lb weiqht on a strinq with a fish-scale from the windscreen header of a Euro-Tub qyro, the scale will read 1 lb in straiqht and level fliqht.
In a constant 60 deqree bank turn, it will read 2 lb.
At the top of a perfectly executed qyro loop (if it could be done) the scale should always indicate at least 1 lb to be safe. Anythinq less than 1 lb is a low-G condition.
It`s not hard to see that transient low-G situations are easy to qet into and since they are danqerous to rotorcraft, recoqnizinq and avoidinq them is important.
Vance says
. This is a key point. All pilots, especially rotorcraft pilots, should fully understand low-G condition, what it is, what all can cause it, how to recoqnize its onset, and how to avoid it completely. In other words, rotorcraft pilots should never FEEL COMFORTABLE WITh...qettinq liqht in the seat, even for a moment.
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