Post by volkerboehme on Aug 10, 2008 12:01:16 GMT -5
FSaviator has some comments:
I have been busy with C-46 beta testing, but now have time to add my thoughts to this thread which is in part about my flight dynamics for the L-049A, but I will get to them last.
<< I have a couple of (probably stupid) questions concerning the FDZigns L049.>>
In aviation there are no stupid questions only dumb silences.
<<It seems that the rudders aren't effective to keep it aligned and I end up landing on the grass either to the left or right of the runway! >>
Aircraft are turned using aileron not rudder. There is a crosswind landing technique in which rudder is used to align the wheels with the runway just before touchdown, but at this stage of your propliner training I recommend that you use only aileron to align the aircraft with the runway. One wing may be a little lower than the other and you should allow one wheel to touchdown before the other if necessary. You can investigate other more difficult and potentially superior techniques for crosswind landing later. In general large propliners are not sideslipped down the approach.
You say that you did not have a crosswind, but that is probably false. I will get back to that.
Rudder is used to prevent or induce slip. You should aim to prevent slip; which means that you must use rudder to centre the slip ball or slip needle of the turn and slip gauge as you vary bank and turn rate with aileron. If you turn auto co-ordination on in the realism screen FS9 will try to prevent slip for you. If you are using a twist grip to apply rudder you may need to do that as the full range of motion in many joysticks precludes sensitive use of rudder to prevent slip.
Many FS users induce slip because their rudder axis 'spikes' or their twist grip rudder null zone is too small. They apply rudder when they only intended to apply aileron. You may be making unintended rudder inputs. Check your null zones and the extent of rudder spiking.
When flying the secret is to make only many very small adjustments. The main problem in this case is probably 'over control'. Maarten Brouwer's post on that subject is right on the money. We have all shared that experience either in a real aeroplane, or in a simulator, or both.
Gliders require more active and precise use of rudder than propliners. In addition gliders should never be landed one (wheel) wing low since they don’t have outer wheels.
<<First thing, make sure realism sliders are turned up all the way, EXCEPT for "P-Factor". This (..like gravity..) is HIGHLY over modelled in FS with no practical work around.>>
The aircraft.cfg should already contain the following lines of code.
[flight_tuning]
p_factor_on_yaw=0.2
torque_on_roll=0.2
Consequently P-factor and torque should not be part of this problem. Gravity is modelled perfectly within FS9. I think the poster must have intended to refer to something else (gyroscopic effects??).
Most but not all aircraft can sideslip. Turning auto co-ordination on reduces that ability but (side) slipping is not the same thing as drifting or negating drift. With a crosswind blowing across the approach course avoid drifting off course by applying a very small angle of bank at zero slip to hold the approach course.
You are following the handling notes correctly, but perhaps not exactly. Any lack of exactitude is not the problem in this case.
<<What your seeing at about 300 AGL is the "ground effect" kicking in. In most default aircraft, it's hardly noticeable, except in the helicopters, but it's not just a whirlybird thing. You'll get used to it. >>
No. In FS9 ground effect is a flight dynamics variable, but normally it exists only when aircraft height is below one wingspan and that is true in this case. It never induces or negates roll or yaw in FS9. It can negate them in real life.
What you seem to be reporting is wind sheer at about 300 AGL. The 'fair weather’ theme has none, but many FS9 users neglect to set theme rate of change to zero and so weather of all types is steadily injected increasing flight difficulty. Note also that any theme can be selected, but not active if the 'themes radio button' is not selected.
The L-049A should be landed with full flap deployed as per the handling notes. Failure to deploy FLAP 3 reduces roll and yaw stability and causes heading to wander more because it requires final approach to be made at higher AoA. Some other propliners differ.
<<For takeoff, be sure you set your RPM for (..I think it's ..) 2600 rpm (...that shows as 76% prop pitch on the FE Panel) and 42" MAP, not full throttle. You'll see it in FSAviators reference file. It's a small, but important consideration if you want to see the same results as the flight notes indicate. >>
My handling notes are explicit;
********************************
CALL for TOGA POWER (2200hp)
PROPS FULLY FINE
IF runway => 8000 QNH set 2600 rpm
FULL THROTTLE
********************************
Full throttle is always used and 2600 rpm is set only before departing a runway whose altitude is above 8000 feet QNH.
<<If you are getting a strange "crosswind" on short final, it may not be you. FS has this strange wind transition zone between the ground and a level several hundred feet above ground. This is if you use real word weather, you download it, then fly. If you choose of the preset FS weather conditions, you won't get it. The only way to overcome this is to buy the extended version of FSUIPC. >>
Payware FSUIPC can be used to prevent crosswinds below a height chosen by the user so that the user never needs to make a crosswind landing even if they need to fly an extended crosswind approach. Payware FSUIPC also smoothes sudden transitions between wind layers as defined in 'FS9 real weather downloads' (thus negating false windsheer). Those layers do not relate to height, they relate to altitude. If the altitude at which wind suddenly backs, veers or increases in 'real weather' approximates the altitude of the landing runway sudden false wind sheer is encountered without payware FSUIPC. MSFS is broken in many ways.
<<Right now I'm just trying to learn how to land the plane. I'm using "Fair Weather" theme ( I get about a 20 knot wind from the west at about 5000 ft) but (supposedly) there's no wind at ground level. >>
You may have invoked that theme, but at some point you have not set rate of change to zero and thus induced the problem. The existence of any wind proves that. It sounds as though the wind suddenly goes from 20 KTS to zero at an altitude that just happens to be about 300 AGL due to failure to zero the weather rate of change. You may be re-importing the problem over and over gain from a .FLT initiation file created on a day when you did not zero rate of change. Thus if you now have zero rate of change selected the problem persists and repeats for ever.
This is a persistent debugging problem for developers since users report they have no weather acting on the aircraft, but they do. They keep reloading it. Some just reload unfortunate wind conditions, and others persistently reload tons of accumulated invisible ice. This is why users are told over and over again to always initiate FS9 using a default Microsoft flight that they have never altered, or ever saved. They are the only 'clean' files on any user’s computer. All the others have accumulated junk from prior flights.
<< I am wondering if the FSUPIC might be worth purchasing anyway since I've downloaded several propliners (DC-4, DC-6B as well as the Constellation) recently. >>
I suggest that you put that decision off until later. It’s good, but it’s expensive and you may be able to solve all the problems that you have in other ways for the time being.
<<Naturally, as I get more familiar with it I'll switch to "real world" weather (which never seems to be quite right as I can look outside here near Pittsburgh and often see clear skies but "real world" weather gives me snow, overcast and general IFR weather, even worse than Seattle!).>>
The server used by Microsoft is often very out of date and sometimes has many reports missing. The latest available data for real aircrew is always available here instead. Remember the data is only collated once per hour, after the hour is over, and has to arrive from all over the planet before it can be collated.
weather.noaa.gov/pub/data/observations/metar/cycles/
I recommend that propliner fans obtain freeware FSMetar from here;
personal.telefonica.terra.es/web/fsmetar/
and investigate its options and the means by which it will reveal actual weather data inside FS9 (after import). By default it will download the latest two hours from the server above which helps to fill in missing reports from observing stations which may be shut for one of the hours.
Also learn to choose which hour you download from the NOAA server (probably the one with most data), using your web browser and how to save it for import by FSMetar later. Give it a name that means something, not just a date.
<<Just a "by the way" for anyone who wants to know, I'm flying a standard pattern about 1500 ft AGL, using 35- 45% fuel (AC weight just over 71000 lbs at takeoff). I want to try and land "heavy" meaning close to the max landing weight. I think that practicing close to the max landing weight makes it easier to land a lighter plane, but I could be wrong in this case. >>
If you land at the weight cited in the handling notes you do not need to recalculate the Vref cited in the handling notes. Vref varies with square root of landing weight. You must target Vref at a height of 50 feet.
At 71,000lbs Vref is 95 * SQR(71/77.2) = 91 KIAS.
*********************
Established final
FLAP - STAGE 3 (100%)
REDUCE < 120 KIAS
Cross airfield boundary 95 KIAS (@ 77,200lbs)
FLARE and LAND
*********************
Fowler flaps are extended in per cent not degrees because they increase wing area, not just wing camber.
Landing at any weight from MLW downwards is equally easy *provided* you calculate and then nail Vref for that weight. How to deal with wind sheer etc., is something that you should study only later.
The way to learn how to fly the final approach and landing in a propliner is first to ensure that you really are controlling the weather induced difficulty. Preferably by invoking the user controlled weather option. Then allow the aircraft to autocapture an ILS using the APR mode of a full function AP. The L-049A has one. Just after it does, save that situation for further training. Now let the approach proceed. At first turn the AP off very late in the approach, after you have deployed FLAP 3 and are confident that you have developed the skill to achieve Vref at 50 QFE using APR mode. Gradually turn the AP off sooner and sooner at higher and higher altitudes. Hand fly more of the final approach, eventually from several miles out on the centreline. Only later from base leg.
The other thing to bear in mind is the need to trim not only the elevators, but also the ailerons and/or rudder of powerful aircraft. The trim required depends on the power applied. If you never use the 4 and 6 keys on your numpad as aileron keys I suggest that you redefine them as either aileron trim or rudder trim. When you have a lot of power applied to the L-049A it will roll and yaw unless you trim either the ailerons or the rudder to counteract the high power roll and yaw. The lower the IAS and the more the power applied the greater the trim setting required. You can hold off the roll and yaw manually with your joystick, but it will soon become tiring, and a twist grip may lack the necessary precision. However as I indicated earlier during the approach realistic power settings barely induce roll and yaw even at low IAS.
Now to the flight dynamics. Handling is probably more difficult than the real thing, especially at low IAS. The solution is to be very gentle with the aeroplane. Make small gentle corrections in pitch and roll, but not in yaw. The excess difficulty, (when users really have nil weather), is not huge, but is due to my dihedral data which is too low in the air file. This cannot be fixed other than by editing of the dihedral data in the air file and it is not the value that is most in need of fixing in relation to all aspects of L-049A operation anyway. Once anyone starts to adjust these things one thing impacts another and a large rewrite is needed. I don't have time right now so for the time being the only answer is to be even gentler with the old lady than was necessary in real life. She is a little unstable in roll and yaw at low IAS and excessively unforgiving of ‘over control’ so she is a good aeroplane in which to learn the need to avoid it.
FSAviator
I have been busy with C-46 beta testing, but now have time to add my thoughts to this thread which is in part about my flight dynamics for the L-049A, but I will get to them last.
<< I have a couple of (probably stupid) questions concerning the FDZigns L049.>>
In aviation there are no stupid questions only dumb silences.
<<It seems that the rudders aren't effective to keep it aligned and I end up landing on the grass either to the left or right of the runway! >>
Aircraft are turned using aileron not rudder. There is a crosswind landing technique in which rudder is used to align the wheels with the runway just before touchdown, but at this stage of your propliner training I recommend that you use only aileron to align the aircraft with the runway. One wing may be a little lower than the other and you should allow one wheel to touchdown before the other if necessary. You can investigate other more difficult and potentially superior techniques for crosswind landing later. In general large propliners are not sideslipped down the approach.
You say that you did not have a crosswind, but that is probably false. I will get back to that.
Rudder is used to prevent or induce slip. You should aim to prevent slip; which means that you must use rudder to centre the slip ball or slip needle of the turn and slip gauge as you vary bank and turn rate with aileron. If you turn auto co-ordination on in the realism screen FS9 will try to prevent slip for you. If you are using a twist grip to apply rudder you may need to do that as the full range of motion in many joysticks precludes sensitive use of rudder to prevent slip.
Many FS users induce slip because their rudder axis 'spikes' or their twist grip rudder null zone is too small. They apply rudder when they only intended to apply aileron. You may be making unintended rudder inputs. Check your null zones and the extent of rudder spiking.
When flying the secret is to make only many very small adjustments. The main problem in this case is probably 'over control'. Maarten Brouwer's post on that subject is right on the money. We have all shared that experience either in a real aeroplane, or in a simulator, or both.
Gliders require more active and precise use of rudder than propliners. In addition gliders should never be landed one (wheel) wing low since they don’t have outer wheels.
<<First thing, make sure realism sliders are turned up all the way, EXCEPT for "P-Factor". This (..like gravity..) is HIGHLY over modelled in FS with no practical work around.>>
The aircraft.cfg should already contain the following lines of code.
[flight_tuning]
p_factor_on_yaw=0.2
torque_on_roll=0.2
Consequently P-factor and torque should not be part of this problem. Gravity is modelled perfectly within FS9. I think the poster must have intended to refer to something else (gyroscopic effects??).
Most but not all aircraft can sideslip. Turning auto co-ordination on reduces that ability but (side) slipping is not the same thing as drifting or negating drift. With a crosswind blowing across the approach course avoid drifting off course by applying a very small angle of bank at zero slip to hold the approach course.
You are following the handling notes correctly, but perhaps not exactly. Any lack of exactitude is not the problem in this case.
<<What your seeing at about 300 AGL is the "ground effect" kicking in. In most default aircraft, it's hardly noticeable, except in the helicopters, but it's not just a whirlybird thing. You'll get used to it. >>
No. In FS9 ground effect is a flight dynamics variable, but normally it exists only when aircraft height is below one wingspan and that is true in this case. It never induces or negates roll or yaw in FS9. It can negate them in real life.
What you seem to be reporting is wind sheer at about 300 AGL. The 'fair weather’ theme has none, but many FS9 users neglect to set theme rate of change to zero and so weather of all types is steadily injected increasing flight difficulty. Note also that any theme can be selected, but not active if the 'themes radio button' is not selected.
The L-049A should be landed with full flap deployed as per the handling notes. Failure to deploy FLAP 3 reduces roll and yaw stability and causes heading to wander more because it requires final approach to be made at higher AoA. Some other propliners differ.
<<For takeoff, be sure you set your RPM for (..I think it's ..) 2600 rpm (...that shows as 76% prop pitch on the FE Panel) and 42" MAP, not full throttle. You'll see it in FSAviators reference file. It's a small, but important consideration if you want to see the same results as the flight notes indicate. >>
My handling notes are explicit;
********************************
CALL for TOGA POWER (2200hp)
PROPS FULLY FINE
IF runway => 8000 QNH set 2600 rpm
FULL THROTTLE
********************************
Full throttle is always used and 2600 rpm is set only before departing a runway whose altitude is above 8000 feet QNH.
<<If you are getting a strange "crosswind" on short final, it may not be you. FS has this strange wind transition zone between the ground and a level several hundred feet above ground. This is if you use real word weather, you download it, then fly. If you choose of the preset FS weather conditions, you won't get it. The only way to overcome this is to buy the extended version of FSUIPC. >>
Payware FSUIPC can be used to prevent crosswinds below a height chosen by the user so that the user never needs to make a crosswind landing even if they need to fly an extended crosswind approach. Payware FSUIPC also smoothes sudden transitions between wind layers as defined in 'FS9 real weather downloads' (thus negating false windsheer). Those layers do not relate to height, they relate to altitude. If the altitude at which wind suddenly backs, veers or increases in 'real weather' approximates the altitude of the landing runway sudden false wind sheer is encountered without payware FSUIPC. MSFS is broken in many ways.
<<Right now I'm just trying to learn how to land the plane. I'm using "Fair Weather" theme ( I get about a 20 knot wind from the west at about 5000 ft) but (supposedly) there's no wind at ground level. >>
You may have invoked that theme, but at some point you have not set rate of change to zero and thus induced the problem. The existence of any wind proves that. It sounds as though the wind suddenly goes from 20 KTS to zero at an altitude that just happens to be about 300 AGL due to failure to zero the weather rate of change. You may be re-importing the problem over and over gain from a .FLT initiation file created on a day when you did not zero rate of change. Thus if you now have zero rate of change selected the problem persists and repeats for ever.
This is a persistent debugging problem for developers since users report they have no weather acting on the aircraft, but they do. They keep reloading it. Some just reload unfortunate wind conditions, and others persistently reload tons of accumulated invisible ice. This is why users are told over and over again to always initiate FS9 using a default Microsoft flight that they have never altered, or ever saved. They are the only 'clean' files on any user’s computer. All the others have accumulated junk from prior flights.
<< I am wondering if the FSUPIC might be worth purchasing anyway since I've downloaded several propliners (DC-4, DC-6B as well as the Constellation) recently. >>
I suggest that you put that decision off until later. It’s good, but it’s expensive and you may be able to solve all the problems that you have in other ways for the time being.
<<Naturally, as I get more familiar with it I'll switch to "real world" weather (which never seems to be quite right as I can look outside here near Pittsburgh and often see clear skies but "real world" weather gives me snow, overcast and general IFR weather, even worse than Seattle!).>>
The server used by Microsoft is often very out of date and sometimes has many reports missing. The latest available data for real aircrew is always available here instead. Remember the data is only collated once per hour, after the hour is over, and has to arrive from all over the planet before it can be collated.
weather.noaa.gov/pub/data/observations/metar/cycles/
I recommend that propliner fans obtain freeware FSMetar from here;
personal.telefonica.terra.es/web/fsmetar/
and investigate its options and the means by which it will reveal actual weather data inside FS9 (after import). By default it will download the latest two hours from the server above which helps to fill in missing reports from observing stations which may be shut for one of the hours.
Also learn to choose which hour you download from the NOAA server (probably the one with most data), using your web browser and how to save it for import by FSMetar later. Give it a name that means something, not just a date.
<<Just a "by the way" for anyone who wants to know, I'm flying a standard pattern about 1500 ft AGL, using 35- 45% fuel (AC weight just over 71000 lbs at takeoff). I want to try and land "heavy" meaning close to the max landing weight. I think that practicing close to the max landing weight makes it easier to land a lighter plane, but I could be wrong in this case. >>
If you land at the weight cited in the handling notes you do not need to recalculate the Vref cited in the handling notes. Vref varies with square root of landing weight. You must target Vref at a height of 50 feet.
At 71,000lbs Vref is 95 * SQR(71/77.2) = 91 KIAS.
*********************
Established final
FLAP - STAGE 3 (100%)
REDUCE < 120 KIAS
Cross airfield boundary 95 KIAS (@ 77,200lbs)
FLARE and LAND
*********************
Fowler flaps are extended in per cent not degrees because they increase wing area, not just wing camber.
Landing at any weight from MLW downwards is equally easy *provided* you calculate and then nail Vref for that weight. How to deal with wind sheer etc., is something that you should study only later.
The way to learn how to fly the final approach and landing in a propliner is first to ensure that you really are controlling the weather induced difficulty. Preferably by invoking the user controlled weather option. Then allow the aircraft to autocapture an ILS using the APR mode of a full function AP. The L-049A has one. Just after it does, save that situation for further training. Now let the approach proceed. At first turn the AP off very late in the approach, after you have deployed FLAP 3 and are confident that you have developed the skill to achieve Vref at 50 QFE using APR mode. Gradually turn the AP off sooner and sooner at higher and higher altitudes. Hand fly more of the final approach, eventually from several miles out on the centreline. Only later from base leg.
The other thing to bear in mind is the need to trim not only the elevators, but also the ailerons and/or rudder of powerful aircraft. The trim required depends on the power applied. If you never use the 4 and 6 keys on your numpad as aileron keys I suggest that you redefine them as either aileron trim or rudder trim. When you have a lot of power applied to the L-049A it will roll and yaw unless you trim either the ailerons or the rudder to counteract the high power roll and yaw. The lower the IAS and the more the power applied the greater the trim setting required. You can hold off the roll and yaw manually with your joystick, but it will soon become tiring, and a twist grip may lack the necessary precision. However as I indicated earlier during the approach realistic power settings barely induce roll and yaw even at low IAS.
Now to the flight dynamics. Handling is probably more difficult than the real thing, especially at low IAS. The solution is to be very gentle with the aeroplane. Make small gentle corrections in pitch and roll, but not in yaw. The excess difficulty, (when users really have nil weather), is not huge, but is due to my dihedral data which is too low in the air file. This cannot be fixed other than by editing of the dihedral data in the air file and it is not the value that is most in need of fixing in relation to all aspects of L-049A operation anyway. Once anyone starts to adjust these things one thing impacts another and a large rewrite is needed. I don't have time right now so for the time being the only answer is to be even gentler with the old lady than was necessary in real life. She is a little unstable in roll and yaw at low IAS and excessively unforgiving of ‘over control’ so she is a good aeroplane in which to learn the need to avoid it.
FSAviator