so 180 auto rotations are the hardest safety maneuver right now. i have a lot of trouble setting my attitude to hold the airspeed! sometimes i dont pull back on the cyclic enough either, or make a sharp enough turn. luckily i pay enough attention to the RPM but i'm struggling at managing all things when i need to do them. i cant wait for ever to turn after i set my attitude in an auto because i will fall short of my landing point. and if i cant keep my attitude at 65 knots i will haul ass or slow down too much. if the rotor RPM drops from coning i HAVE to raise the collective AND twist the throttle on and go around if that happens. i need to have it in the green or yellow before i start my flare at the end.
The flare has to be gentle too, i cant just sit there and hold it back. i have to lower the collective a little as i pull back and turn on throttle just after i see the needles start for the red. i have to let it go there, and then as soon as that happens i gotta twist on the throttle and push the nose forward else the helicopter will be too far aft and the tail rotor will risk being blown off. cant have that happen!
I can't stare at my airspeed and RPM gauge so much either!
Thursday, July 31, 2008
Friday, July 25, 2008
DRAG review
the ones starred are the topics i still need eventually double check eventually.
1.) the coefficient of an airfoil is determined by its shape and area, its minimum value is found at zero degrees angle of attack.
2.) the three types of drag experienced by a helicopter in forward flight are profile, parasite and induced.
*3.) when the speed of a helicopter increases from 20 knots to 60 knots, parasite drag increases by a factor of four.
*4.) form drag can be reduced by shaping.
5.) skin friction drag is caused by friction between molecules in the turbulent layer which is a retarded layer of air between the airfoil and the wake.
6.)a laminar boundary layer is normally thin, it produces little skin friction drag and is not readily subject to separation from the airfoil surface.
7.) a turbulent boundary layer is normally thick, it produces much skin friction drag and it is readily subject to separation from the airfoil surface.
8.) the point where the laminar boundary layer changes into the turbulent boundary layer is called the transition point.
9.) with an increase in airspeed, skin friction drag increases because the transmission point moves forward and the boundary layer thickens.
10.) induced drag is the result of the differences in lift above and below the airfoil and is directly proportional to induced flow.
11.) with an increase in airspeed, induced drag decreases, and parasite drag increases.
12.) an increase in aspect ratio tends to increase induced drag.
13.) wash out is a structural design which decreases the blade angle from blade root to blade tip.
14.) total drag of a helicopter is low at zero airspeed, it increases with an increase in airspeed.
1.) the coefficient of an airfoil is determined by its shape and area, its minimum value is found at zero degrees angle of attack.
2.) the three types of drag experienced by a helicopter in forward flight are profile, parasite and induced.
*3.) when the speed of a helicopter increases from 20 knots to 60 knots, parasite drag increases by a factor of four.
*4.) form drag can be reduced by shaping.
5.) skin friction drag is caused by friction between molecules in the turbulent layer which is a retarded layer of air between the airfoil and the wake.
6.)a laminar boundary layer is normally thin, it produces little skin friction drag and is not readily subject to separation from the airfoil surface.
7.) a turbulent boundary layer is normally thick, it produces much skin friction drag and it is readily subject to separation from the airfoil surface.
8.) the point where the laminar boundary layer changes into the turbulent boundary layer is called the transition point.
9.) with an increase in airspeed, skin friction drag increases because the transmission point moves forward and the boundary layer thickens.
10.) induced drag is the result of the differences in lift above and below the airfoil and is directly proportional to induced flow.
11.) with an increase in airspeed, induced drag decreases, and parasite drag increases.
12.) an increase in aspect ratio tends to increase induced drag.
13.) wash out is a structural design which decreases the blade angle from blade root to blade tip.
14.) total drag of a helicopter is low at zero airspeed, it increases with an increase in airspeed.
Thursday, July 24, 2008
LIFT review
1.) blade angle is the angular difference between the angle of the blade and plane of rotation.
2.) feathering a blade meas changing its pitch angle around the feathering axis (done so with collective or cyclic).
3.) when an airflow is deflected by an airfoil, the force is acting more or less at right angles to the relative airflow(relative wind) and drag acts parallel to the relative flow.
4.) the two components of total lift reaction are lift, and drag, parallel to the relative airflow.
5.) when an airflow is made to speed up, the pressure with in the flow decreases provided the flow remains constant (Bernoulli's principle.)
6.) when a symmetrical airfoil is placed at a zero degree angle of attack to an airflow, pressures are the same above and below the airfoil.
7.) the lift coefficient of an airfoil is determined by its area and shape.
8.) the peak of the Cl curve represents (coefficient of lift max./coefficient of lift min.), the associated angle of attack is called the pitch angle.
9.) the C/P is the point on the chord line through which all weights are said to act.
10.) the C/P of a symmetrical airfoil remains steady with changes in angle of attack.
11.) the point on the chord line about which no change in pitch moments is felt with changes in angle of attack is called the aerodynamic center.
2.) feathering a blade meas changing its pitch angle around the feathering axis (done so with collective or cyclic).
3.) when an airflow is deflected by an airfoil, the force is acting more or less at right angles to the relative airflow(relative wind) and drag acts parallel to the relative flow.
4.) the two components of total lift reaction are lift, and drag, parallel to the relative airflow.
5.) when an airflow is made to speed up, the pressure with in the flow decreases provided the flow remains constant (Bernoulli's principle.)
6.) when a symmetrical airfoil is placed at a zero degree angle of attack to an airflow, pressures are the same above and below the airfoil.
7.) the lift coefficient of an airfoil is determined by its area and shape.
8.) the peak of the Cl curve represents (coefficient of lift max./coefficient of lift min.), the associated angle of attack is called the pitch angle.
9.) the C/P is the point on the chord line through which all weights are said to act.
10.) the C/P of a symmetrical airfoil remains steady with changes in angle of attack.
11.) the point on the chord line about which no change in pitch moments is felt with changes in angle of attack is called the aerodynamic center.
Review on the atmosphere
1.) the three elements that determine air density are temperature, pressure, and humidity
2.) air pressure is the result of the height of a column of air above a datum (reference point).
3.) with increasing altitude, air pressure decreases, which causes air density to decreases
4.) the atmosphere is warmed from below
5.) with increasing altitude, air temperature decreases and this tends to increase air density
6.) the combined effect of pressure and temperature changes with increasing altitude causes an overall decrease in air density.
7.) the standard atmosphere (ISA, international standard atmosphere) assumes that seal level pressure is 29.92 and seal level air temperature is 59.degrees Fahrenheit. The temperature lapse rate is 3.5degrees Fahrenheit/1000 feet.
8.) a low density altitude results when pressure is higher (than 29.92), temperature is lower, and the moisture content is dryer.
2.) air pressure is the result of the height of a column of air above a datum (reference point).
3.) with increasing altitude, air pressure decreases, which causes air density to decreases
4.) the atmosphere is warmed from below
5.) with increasing altitude, air temperature decreases and this tends to increase air density
6.) the combined effect of pressure and temperature changes with increasing altitude causes an overall decrease in air density.
7.) the standard atmosphere (ISA, international standard atmosphere) assumes that seal level pressure is 29.92 and seal level air temperature is 59.degrees Fahrenheit. The temperature lapse rate is 3.5degrees Fahrenheit/1000 feet.
8.) a low density altitude results when pressure is higher (than 29.92), temperature is lower, and the moisture content is dryer.
Physics Review
this is all from a new book i got to continue to prepare for the FAA exam this fall.
1.) the inertia of a body is determined by its speed, changes in altitude do not affect inertia.
2.) when a helicopter climbs at increasing airspeed, its inertia does not change but its momentum increases.
3.)when the mass of air thru a rotor system becomes less, the downward acceleration must be greater to provide the same opposing force.
4.) when a helicopter is in a steady rate turn at a constant airspeed, the aircraft is NOT accelerating b/c its constantly changing its direction.
5.) during a constant radius/steady rate turn at a constant airspeed, all forces acting on the helicopter are balanced and the helicopter IS in equilibrium.
6.) ignoring fuel burn off, as an aircraft continues to gain altitude, its mass doesn't vary, earth attractional forces become weaker and aircraft weight becomes less.
7.) assuming the mass of an aircraft and its airspeed remain constant, the centripetal force required to turn it on a reducing radius must be greater.
8.) a couple consists of TWO equal, parallel and opposite forces, and when these forces act around a point equidistant between the forces, the couple tends to produce torque.
9.) the strength of a moment is decreased with the lever arm increases.
10.) assuming your helicopter has a constant mass, its kinetic energy quadruples when tis airspeed doubles.
im certain these are all correct but eventually i will be double checking them.
next review will be on the atmosphere.
1.) the inertia of a body is determined by its speed, changes in altitude do not affect inertia.
2.) when a helicopter climbs at increasing airspeed, its inertia does not change but its momentum increases.
3.)when the mass of air thru a rotor system becomes less, the downward acceleration must be greater to provide the same opposing force.
4.) when a helicopter is in a steady rate turn at a constant airspeed, the aircraft is NOT accelerating b/c its constantly changing its direction.
5.) during a constant radius/steady rate turn at a constant airspeed, all forces acting on the helicopter are balanced and the helicopter IS in equilibrium.
6.) ignoring fuel burn off, as an aircraft continues to gain altitude, its mass doesn't vary, earth attractional forces become weaker and aircraft weight becomes less.
7.) assuming the mass of an aircraft and its airspeed remain constant, the centripetal force required to turn it on a reducing radius must be greater.
8.) a couple consists of TWO equal, parallel and opposite forces, and when these forces act around a point equidistant between the forces, the couple tends to produce torque.
9.) the strength of a moment is decreased with the lever arm increases.
10.) assuming your helicopter has a constant mass, its kinetic energy quadruples when tis airspeed doubles.
im certain these are all correct but eventually i will be double checking them.
next review will be on the atmosphere.
Density altitude VS pressure altitude
HIGH DENSITY ALTITUDE:
1.) pressure altitude is less than 29.92in.Hg.
2.)temperature is warmer
3.) air is moist
LOW DENSITY ALTITUDE:
1.) Press greater than 29.92in.HG
2.) temperature is cooler
3.) air dryer
pressure goes down => density goes down=>high pressure altitude means=>less performance (akin to high elevations)
pressure goes up=>density goes up=>low pressure altitude means=>more performance
(akin to low elevations)
pressure altitude is not directly affected by temperature as density altitude is.
1.) pressure altitude is less than 29.92in.Hg.
2.)temperature is warmer
3.) air is moist
LOW DENSITY ALTITUDE:
1.) Press greater than 29.92in.HG
2.) temperature is cooler
3.) air dryer
------------VS------------
PRESSURE ALTITUDEpressure goes down => density goes down=>high pressure altitude means=>less performance (akin to high elevations)
pressure goes up=>density goes up=>low pressure altitude means=>more performance
(akin to low elevations)
pressure altitude is not directly affected by temperature as density altitude is.
Monday, July 21, 2008
WOTFEEL
WIND-Where is it coming from?
OBSTACLES-are there any in the area you want to land in? how do you avoid it? will the wind be a problem?
TURBULENCE-mechanical turbulence? air turbulence? none at all?
FORCED LANDING-whats the best place if you had to land somewhere else (for auto or just an emergency)?
ENTRY-based on wind and obstacles (like trees/buildings), whats the best way to enter? there may be more than one
EXIT-same as entry, whats the best way to exit?
LANDING-whats the condition of your landing spot? it very well may not be a perfect heli pad!
the landing may be a steep approach or a normal one. Take off can be a normal take off or a MaxPower take off.
----IF YOURE COMING IN TOO FAST, MORE THAN 300 FT DESCENT, GO AROUND!!!----
OBSTACLES-are there any in the area you want to land in? how do you avoid it? will the wind be a problem?
TURBULENCE-mechanical turbulence? air turbulence? none at all?
FORCED LANDING-whats the best place if you had to land somewhere else (for auto or just an emergency)?
ENTRY-based on wind and obstacles (like trees/buildings), whats the best way to enter? there may be more than one
EXIT-same as entry, whats the best way to exit?
LANDING-whats the condition of your landing spot? it very well may not be a perfect heli pad!
the landing may be a steep approach or a normal one. Take off can be a normal take off or a MaxPower take off.
----IF YOURE COMING IN TOO FAST, MORE THAN 300 FT DESCENT, GO AROUND!!!----
Monday, July 14, 2008
a lil turbulence
well apparently it is confirmed. i have several things i need to master in flying that helicopter before i can call myself good. God i am slow -_-. I enjoy it but man, these past couple of lessons have really shown where my errors and bad habits lack.
one, i cant do high reconnaissance approaches (i think) worth crap. im slow to planing ahead and my approaches are therefore a little shifty. sometimes they're close but not quite, others, i found miserable. i couldn't even decide i had to go around and try again. if your descent rate is still more than 300 feet a minute by the time you get too close for comfort for your landing spot, you have to go around, because obviously its not safe for a helicopter. see, I know that. but for some reason its not quite getting to me while in practice. i guess i'm so worked up on keeping the helicopter on its path whatever im 'focusing on' isn't giving me the numbers i wanna see on my instruments, which is because im too concerned with IT and not with what i want to do!
two, my autorotations are actually fine, only its the ending flare maneuver that i struggle with. i need to push the nose down. yes theres a difference between a push and a shove but i need to push it steadily down. you cannot let the helicopter flare up and linger there in something as dangerous in an auto rotation. i need to be more forceful!
three: i need to pay attention to details as well. i forgot another something on my shut down checklist. the clutch! how lame! here id gotten it off numerous times before and yet here i forget it, just like i did with making sure the throttle wasnt closed, ugg.
*sigh* how can i change these habits, and adapt? how can i calm down and think clearer than ever?
i just need to slow down, pick solid points to measure up on, and glide down gradually. i guess I'm a little better than i was before, but meh, who cares about that. im the one thats always worrying about the future, for some reason my mindset changes when im in the helicopter. I'm glued to making sure that everything i currently see is okay. WTF? things are going to change, so i need to plan AHEAD AND ADJUST. i should know this and thats why im berating myself about it now. i gotta change these habits if i think im fit to fly this machine.
i just find it so ironic, here i am always planning ahead over every little thing i want in life, yet i can just barely do it in a helicopter o_O. weeell thats about to change!
one, i cant do high reconnaissance approaches (i think) worth crap. im slow to planing ahead and my approaches are therefore a little shifty. sometimes they're close but not quite, others, i found miserable. i couldn't even decide i had to go around and try again. if your descent rate is still more than 300 feet a minute by the time you get too close for comfort for your landing spot, you have to go around, because obviously its not safe for a helicopter. see, I know that. but for some reason its not quite getting to me while in practice. i guess i'm so worked up on keeping the helicopter on its path whatever im 'focusing on' isn't giving me the numbers i wanna see on my instruments, which is because im too concerned with IT and not with what i want to do!
two, my autorotations are actually fine, only its the ending flare maneuver that i struggle with. i need to push the nose down. yes theres a difference between a push and a shove but i need to push it steadily down. you cannot let the helicopter flare up and linger there in something as dangerous in an auto rotation. i need to be more forceful!
three: i need to pay attention to details as well. i forgot another something on my shut down checklist. the clutch! how lame! here id gotten it off numerous times before and yet here i forget it, just like i did with making sure the throttle wasnt closed, ugg.
*sigh* how can i change these habits, and adapt? how can i calm down and think clearer than ever?
i just need to slow down, pick solid points to measure up on, and glide down gradually. i guess I'm a little better than i was before, but meh, who cares about that. im the one thats always worrying about the future, for some reason my mindset changes when im in the helicopter. I'm glued to making sure that everything i currently see is okay. WTF? things are going to change, so i need to plan AHEAD AND ADJUST. i should know this and thats why im berating myself about it now. i gotta change these habits if i think im fit to fly this machine.
i just find it so ironic, here i am always planning ahead over every little thing i want in life, yet i can just barely do it in a helicopter o_O. weeell thats about to change!
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