Flaps lift/drag

[Bert Pieke 7,584]

Does anyone have a problem with the airplane ballooning when you drop the flaps during an approach?

The autopilot has trouble controlling the airplane when I do it..  (maybe an indication of poor airmanship on my part..)

I've tried to apply the PC12 flaps lift/drag mods with some success, but not quite sure what I am doing, especially since there are two flaps sections (0,1) with slightly different degrees of flaps (intentional??) 

Edited March 10, 2018 by Bert Pieke

[tanker 15]

I have had the same problem. If I drop flaps to 20 degrees while on descent on the glide slope, the aircraft balloons and then the autopilot over corrects and the approach looks like a sine wave. It is normal on many aircraft to get some ballooning as flaps are extended, after all, they do increase lift (and drag), but not as much as we are seeing on the f50. One factor is excessive speed. I tend to start down final at 120 kias and expect the flaps to slow the aircraft. On this aircraft, I have better luck configuring to 20 degrees flaps and gear down before intercepting the glide slope, then hold 95 to 100 kias down to decision height.

 

[scianoir 610]

2 hours ago, Bert Pieke said:

The autopilot has trouble controlling the airplane when I do it.. 

 

14 minutes ago, tanker said:

the approach looks like a sine wave

I have noticed this too and although the ballooning occurs with each stage of flap extension is seems to be at its worst going from 5-10 degrees where the balloon is of the order of 500-600 ft/min whereas at the other stages of flap extension it is around 300 ft/min. As you say the autopilot, if you are tracking the glideslope, has difficulty controlling it and the result seems to be a series of over corrections resulting in the approach, as tanker says, looking like a sine wave.

I have to say that the ballooning on flap extension seems to be a Carenado feature and it is perhaps not quite as bad on the F50 as it is on some other Carenado aircraft! For better or for worse, with some of the Carenado types I too have taken to setting the final flap configuration before intercepting the glideslope for this reason and at least it avoids the sine wave on the glideslope. This however doesn't necessarily mirror the real world where pilots at busy airports are often asked to maintain a high speed (perhaps as much as 160-170kts) until 4 miles from touchdown which might preclude earlier extension of landing flaps.

Bill

[Bert Pieke 7,584]

OK - here is something to try (back up your aircraft.cfg file first..)

[flaps.0]
type             = 1                                    // 1 - tail, 2 - lead
span-outboard    = 0.65                                 // 0.0 .. 1.0
extending-time   = 15                                   // seconds
flaps-position.0 = 0                                    // degrees
flaps-position.1 = 5                                    // degrees
flaps-position.2 = 10                                   // degrees
flaps-position.3 = 15                                   // degrees
flaps-position.4 = 20                                   // degrees
flaps-position.5 = 25                                   // degrees
flaps-position.6 = 35                                   // degrees
damaging-speed  = 190                                   // KIAS
blowout-speed   = 195                                   // KIAS
system_type      =  1
lift_scalar     =  0.7           // 0
drag_scalar     =   1.9        // 0
pitch_scalar = 0.8 // new

[flaps.1]
type             = 1                                    // 1 - tail, 2 - lead
span-outboard    = 0.65                                 // 0.0 .. 1.0
extending-time   = 15                                   // seconds
flaps-position.0 = 0                                    // degrees
flaps-position.1 = 5                                    // degrees
flaps-position.2 = 10                                   // degrees
flaps-position.3 = 15                                   // degrees
flaps-position.4 = 20                                   // degrees
flaps-position.5 = 25                                   // degrees
flaps-position.6 = 35                                   // degrees
damaging-speed  = 190                                   // KIAS
blowout-speed   = 195                                   // KIAS
system_type      =  1
lift_scalar     =   0.7      // 1
drag_scalar     =  1.9   // 1
pitch_scalar = 0.8 // new

 

[scianoir 610]

I thought I would give you some early feedback having just shot 3 approaches to test the new flap config. Unfortunately I couldn't really make a useful assessment on the first approach because of quite bad turbulence so I turned off real weather in AS16 and tried again in calm conditions. 

I have to say that I couldn't identify a huge difference with the mod and I still seemed to be seeing a balloon with a climb rate of about 200-300ft/min on extension of each stage of flaps although this did represent an improvement from previously on going from flaps 5 to flaps 10. I will however shoot a few more approaches tonight if I get a chance or tomorrow as I guess the intensity of any ballooning will also depend on the airspeed which I haven't really taken into account.

Bill

[jahurz 9]

7 hours ago, scianoir said:

I thought I would give you some early feedback having just shot 3 approaches to test the new flap config. Unfortunately I couldn't really make a useful assessment on the first approach because of quite bad turbulence so I turned off real weather in AS16 and tried again in calm conditions. 

I have to say that I couldn't identify a huge difference with the mod and I still seemed to be seeing a balloon with a climb rate of about 200-300ft/min on extension of each stage of flaps although this did represent an improvement from previously on going from flaps 5 to flaps 10. I will however shoot a few more approaches tonight if I get a chance or tomorrow as I guess the intensity of any ballooning will also depend on the airspeed which I haven't really taken into account.

Bill

Pitch behavior is a lil sensitive on this plane than in real life according the friends who flew the real thing. Also in norm traffic airports the final flaps configuration occurs very late due to speed limitation on approach as most of the time we'd be sharing with category D planes. So many times flaps 25(Flaps 35 is never used unless steep approaches and runway length below 1400m) is only lowered at e,g 1200feet and stabilizing at 1000feet for certain airports. For the ATR72 operations in Borneo, the approaches are done at 140-150knots with flaps 15. Then before  they'll cut the speed by 130knots before lowering flaps 30 for about 110-120knots final approach speed and you'd be touching the runway at 96-105knots. The advantage of turboprops would be the ability to stabilize the approaches(limit buffer levels are also dependent on airline procedure) at a way lower altitude than what an a320 or b737 or etc would do. The fokker 50 should be somewhat similar but with lower speeds.

Edited March 12, 2018 by jahurz

[scianoir 610]

Thanks for that information - it's always useful to know how real world operations of a particular aircraft type are carried out.

Bill

[simon747 185]

On 3/10/2018 at 10:46 PM, Bert Pieke said:

OK - here is something to try (back up your aircraft.cfg file first..)

[flaps.0]
type             = 1                                    // 1 - tail, 2 - lead
span-outboard    = 0.65                                 // 0.0 .. 1.0
extending-time   = 15                                   // seconds
flaps-position.0 = 0                                    // degrees
flaps-position.1 = 5                                    // degrees
flaps-position.2 = 10                                   // degrees
flaps-position.3 = 15                                   // degrees
flaps-position.4 = 20                                   // degrees
flaps-position.5 = 25                                   // degrees
flaps-position.6 = 35                                   // degrees
damaging-speed  = 190                                   // KIAS
blowout-speed   = 195                                   // KIAS
system_type      =  1
lift_scalar     =  0.7           // 0
drag_scalar     =   1.9        // 0
pitch_scalar = 0.8 // new

[flaps.1]
type             = 1                                    // 1 - tail, 2 - lead
span-outboard    = 0.65                                 // 0.0 .. 1.0
extending-time   = 15                                   // seconds
flaps-position.0 = 0                                    // degrees
flaps-position.1 = 5                                    // degrees
flaps-position.2 = 10                                   // degrees
flaps-position.3 = 15                                   // degrees
flaps-position.4 = 20                                   // degrees
flaps-position.5 = 25                                   // degrees
flaps-position.6 = 35                                   // degrees
damaging-speed  = 190                                   // KIAS
blowout-speed   = 195                                   // KIAS
system_type      =  1
lift_scalar     =   0.7      // 1
drag_scalar     =  1.9   // 1
pitch_scalar = 0.8 // new

 

I have the lift/drag problem with flaps...does this help any?

Cheers,

 

Simon

[Bert Pieke 7,584]

1 hour ago, simon747 said:

I have the lift/drag problem with flaps...does this help any?

Cheers,

 

Simon

Only one way to find out.. try it! 

[simon747 185]

seemed better; I pre-config flaps before glideslope lock and smooth as butter; I will attempt some more risky scenarios on final with flaps...