Hover Pitch at Different Headspeeds
05-11-2010, 01:39 PM
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Hover Pitch at Different Headspeeds
Hello All,
I am getting ready to start messing with my Idle up modes and I was wondering if the pitch angle of the blades is the same for hovering at lower headspeeds as it is at higher headspeeds.
For Example:
If I hover at +5 degrees at 1650 RPM, Will I still hover at +5 degrees at 1800RPM? Or will I need to bump it down a bit to compensate for higher headspeed?
I will set the hover pitch the same for all modes and try it out, but since this is my first attempt at idle up I want to know what i'm getting myself into. Should I expect a big "Hop" up when I flip the switch? A little "Hop"?
My goal is to eventually be able to raise the headspeed withought climbing in altitude.
I would appreciate anyone's experiences with these settings, and any advice would be great.
I am getting ready to start messing with my Idle up modes and I was wondering if the pitch angle of the blades is the same for hovering at lower headspeeds as it is at higher headspeeds.
For Example:
If I hover at +5 degrees at 1650 RPM, Will I still hover at +5 degrees at 1800RPM? Or will I need to bump it down a bit to compensate for higher headspeed?
I will set the hover pitch the same for all modes and try it out, but since this is my first attempt at idle up I want to know what i'm getting myself into. Should I expect a big "Hop" up when I flip the switch? A little "Hop"?
My goal is to eventually be able to raise the headspeed withought climbing in altitude.
I would appreciate anyone's experiences with these settings, and any advice would be great.
05-11-2010, 02:53 PM
#2
RE: Hover Pitch at Different Headspeeds
Theorethically, the hover pitch angle should diminish as you increase the headspeed. Now; will you notice it? I doubt it. You are constantly making adjustments when flying a helicopter. And I will not even go into the potential moving of the stick when you are reaching for the idle switch.
Now, talk to me a little about your programming. Are you setting up for mid-stick hover or are you setting up for mid-stick zero pitch? It makes a difference, specially if you intend to go inverted when you flip into idle up.
Rafael
Now, talk to me a little about your programming. Are you setting up for mid-stick hover or are you setting up for mid-stick zero pitch? It makes a difference, specially if you intend to go inverted when you flip into idle up.
Rafael
05-11-2010, 04:39 PM
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RE: Hover Pitch at Different Headspeeds
ORIGINAL: Rafael23cc
Now, talk to me a little about your programming. Are you setting up for mid-stick hover or are you setting up for mid-stick zero pitch? It makes a difference, specially if you intend to go inverted when you flip into idle up.
Now, talk to me a little about your programming. Are you setting up for mid-stick hover or are you setting up for mid-stick zero pitch? It makes a difference, specially if you intend to go inverted when you flip into idle up.
For the past year I was hovering at mid stick. Recently, I decided to purchase some carbon fiber blades and decided that it was as good of a time as any to set up my curves for 3D (not that I'm ready for that...ha!)
I now have my hover point at 3/4, and I just about have my curve where i want it in normal mode (with maybe a couple more tweaks to go).
Once I get the normal mode dialed in, I'm gonna check the exact pitch when hovering and use that pitch for Idle up. I just wanted to make sure that the same pitch wouldn't have a different effect at a different headspeed.
05-12-2010, 10:27 AM
#4
RE: Hover Pitch at Different Headspeeds
Well.... here is my 2 cents.....
Do not worry about your hover point, at least on the pitch curve is concerned.... Set up all your pitch curves (Normal, Idle-1 and Idle-2) to go from 0(zero) at mid stick to 100 at full stick. The bottom end is where I have the differences. By having all your curves the same during UPRIGHT flight, you will ensure that the heli will not jump when you switch from Normal to Idle up. (Actually the heli will dive if you have the normal curve with hovering at mid-stick.)
From there, my suggestion is to give the curves a "bend". For the normal curve, you may want a maximum of about -4 degrees. So your curve will be flatter from -4 to 0, then will be steep from 0 to your maximum pitch (normally 10 or 12 degrees)
For the other curves it is up to you. Most people prefer to have only one curve to mess with so they go from their max at the bottom (-12 or -10) to the max at the top of course passing thru 0 at mid-stick. I suggest that you then make the curves identical, just in case you flip the switch too hard and end up in idle-2 instead of Idle-1. I have a less aggressive curve in idle-1 that is capable of going inverted, but not capable of sustaining inverted flight. For that I have the Idle-2 curve.
I hope this makes some sense to you. The hover point now falls "where ever it falls" and since all your curves are the same from 0 to your max pitch, then the heli will behave the same in all curves. You do need to pay attention to your throttle curves.
Rafael
Do not worry about your hover point, at least on the pitch curve is concerned.... Set up all your pitch curves (Normal, Idle-1 and Idle-2) to go from 0(zero) at mid stick to 100 at full stick. The bottom end is where I have the differences. By having all your curves the same during UPRIGHT flight, you will ensure that the heli will not jump when you switch from Normal to Idle up. (Actually the heli will dive if you have the normal curve with hovering at mid-stick.)
From there, my suggestion is to give the curves a "bend". For the normal curve, you may want a maximum of about -4 degrees. So your curve will be flatter from -4 to 0, then will be steep from 0 to your maximum pitch (normally 10 or 12 degrees)
For the other curves it is up to you. Most people prefer to have only one curve to mess with so they go from their max at the bottom (-12 or -10) to the max at the top of course passing thru 0 at mid-stick. I suggest that you then make the curves identical, just in case you flip the switch too hard and end up in idle-2 instead of Idle-1. I have a less aggressive curve in idle-1 that is capable of going inverted, but not capable of sustaining inverted flight. For that I have the Idle-2 curve.
I hope this makes some sense to you. The hover point now falls "where ever it falls" and since all your curves are the same from 0 to your max pitch, then the heli will behave the same in all curves. You do need to pay attention to your throttle curves.
Rafael
05-12-2010, 12:49 PM
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RE: Hover Pitch at Different Headspeeds
Of note here, is your top pitch setting (and bottom when inverted for climb out etc.) relative to overloading your engine.
For example, if you have your top pitch set at +11 degrees at 1650. with no rotor rpm drop at full throttle, then you will have to drop the pitch at full throttle openings, if you want to maintain 1900 or 2000 at top pitch.
It takes a LOT more power to turn 2000/11 then 1650/11. If the motor, when wide open, will just make enough power to turn the rotor at 1650/11 degrees without bogging, then it certainly will not have the power to do so at a 2000 rotor speed and 11 degrees of pitch.
So when you go into idle up at 2000 (or whatever you choose), be sure to lower the top end pitch to a setting that will allow your motor to keep that rotor speed constant without deteriorating.
Of course, as you get better at pitch load manipulation (combining collective and cyclic inputs without overloading the motor and using energy stored in the rotating blades, for very brief moments) then you can add more collective for that brief "pop" in and out of maneuvers, before quickly backing off on it.
For example, if you have your top pitch set at +11 degrees at 1650. with no rotor rpm drop at full throttle, then you will have to drop the pitch at full throttle openings, if you want to maintain 1900 or 2000 at top pitch.
It takes a LOT more power to turn 2000/11 then 1650/11. If the motor, when wide open, will just make enough power to turn the rotor at 1650/11 degrees without bogging, then it certainly will not have the power to do so at a 2000 rotor speed and 11 degrees of pitch.
So when you go into idle up at 2000 (or whatever you choose), be sure to lower the top end pitch to a setting that will allow your motor to keep that rotor speed constant without deteriorating.
Of course, as you get better at pitch load manipulation (combining collective and cyclic inputs without overloading the motor and using energy stored in the rotating blades, for very brief moments) then you can add more collective for that brief "pop" in and out of maneuvers, before quickly backing off on it.
