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Oliver Branaschky

Flaps 1 producing ridiculous amount of drag and lift

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Hi all,

 

ever since installing a couple of new liveries (American Airlines, Southwest, TUIfly; all from the PMDG website) I'm having this strange issue when taking off with flaps 1 and when selecting flaps 1 on approach, respectively.

 

This flaps setting produces a very huge amount of lift and drag. For instance, on climb out, I'm used to lower the nose just a couple degrees in order to accelerate towards flaps up speed. Lately, with these new liveries installed, I have to lower the nose significantly below the horizon to even start accelerating. This only happens with flaps at the 1 position. Flaps 5 is fine.

 

The same applies on approach: I was approaching Palma de Mallorca LEPA today, and once I selected flaps 1 (speed initially around 240 KIAS) speed began to drop rapidly, while the nose was lowered (still in VNAV with A/P engaged) to around -10 degrees.

 

I've exclusively flown the Air Berlin livery for about 8 months and never had this happen before. It only happens with all the new liveries. (Hm, come to think of it, I haven't tried the Air Berlin one after installing the other ones...) Anyway, I don't think this behavior is normal - or is it? Anyone else ever seen this?

 

Thanks for all hints and tips,

 

Oli

 

 

Oliver Branaschky


Oliver Branaschky

 

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I had the issue you described but it was due to fsuipc. If you don't have issues at flaps 0 its not the same problem.

 

Also, flaps 1 at 240 kts is excessive and not proper usage.

Max speed for flaps 1 is around 210 kts.

 

Does the issue persist after a reinstall, and does it happen at slower speeds? ?


AJ Pongress

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I haven't tried a reinstall yet. It does happen at slower speeds (during take-off, as described above). Besides, I don't think 240 KIAS is excessive, Flaps Limit is 250 KIAS, after all. It may not be the most proper usage, but it's still within limitations.

 

 

Oliver Branaschky


Oliver Branaschky

 

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Are you noticing a difference between your vanilla NGX installation and after you installed liveries? Haven't had any program or something playing with lift scalars in the .cfg file or anything? How's your payload loading? Not noticing any way-forward CofG's or anything? Are you seeing the strange attitudes only in descent, or also level flight?

 

 

The leading edge devices (flaps+slats) on these things are very effective, and are extended whenever the trailing edge devices are extended (even partially). Flaps "1" may not seem like a appreciable amount. At flaps 1; with the inboard leading edge flap extended fully, and the slats intermediately, you have a pretty appreciable camber change there. At that speed (~240 kias) you got a lot of airflow as well. With a forward CofG and that high speed, that may be your reason for what seems like strange behaivour.

 

Try playing around with different liveries at different speeds/configurations.


Patrick Houghton

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As far as I am aware the livery itself has nothing to do with the flight characteristics of a given model. However, installing a livery is the same to installing "new airframe in the hangar", different copy if you will. The new copy has its default load distributions and equipment set differently to the other ones well at least until you set the options.

 

Maybe it is the different load setting for the new planes than the ones you're used to? There should not be any difference of the flaps 1 behaviour among the liveries.

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Guest BeaverDriver

Flaps 1 should cause no drag to speak of. That's for lift and reducing the stall speed. If you are getting a lot of drag from that, I'd "step outside" the aircraft as you are going from Flaps 0 to Flaps 1 and see if you really are getting 1 degree of flap. You'll know because 1 degree just moves the flaps aft, not down. The slats too should come out. Try observing what's going on from outside. Something somewhere may be screwing up and in fact you are getting about 10 or so degrees of flap instead of 1.

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Maybe your liveries, corrupted your files somehow, try a reinstall.


Bryan Richards

 

"People depend so much on automation that they forget how to get the automation to work." B.W.

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Flaps 1 should cause no drag to speak of.

 

Trailing edge flaps themselves will indeed create small to no drag. But those leading edge devices... those are not that small...


--Peter Fabian 
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Guest BeaverDriver

No they're not, but they generate lift only. If they produced any significant drag, you'd have CofG problems on extension. All they do is increase the camber of the wing, generating greater lift. The drag coefficient from those is negligible.

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well... nope. The purpose of leading edge devices is not to generate additional lift, but rather to allow for higher AoA (which leads to higher potential lift, but not higher lift at the same airspeed, and also makes possible lower airspeed due to altering stall behaviour).


--Peter Fabian 
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