Pitch angle with gear and flaps

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Mawingo28
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Pitch angle with gear and flaps

Post Mawingo28 »

Once again, I've returned to the fold and am reminded of why A2A really is a great FS producer! Back to the Comanche and have noticed this: Lowering the gear causes a pitch up and lowering the flaps causes a pitch down, contrary to the usually expected responses. I know the wing (and flaps) are further back than some other types and this could cause a 'nose-over' effect with flaps? The gear down causing a pitch up is a surprise and I can't fathom that at all. Anyone?

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Scott - A2A
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Re: Pitch angle with gear and flaps

Post Scott - A2A »

When the gear drops you are left with a large hole under the wing, a tire, strut and gear doors suddenly appear into the wind. And on each airplane this has a different impact on how both the main wing and horizontal stabilator is affected. Some behavior could be due to a vortex being spun off in some random direction. I would just be guessing regarding the gear.

The flaps are much easier to explain. The Comanche flaps, on my earlier model, have almost no drag and really only re-direct air at the flap downward with almost no disturbance. So you get a nice clean arm / force from the flap pushing up from the trailing edge. It also has an affect on the rear stabilator. The nose movement is instant and when you grab the flaps, you can rock the nose up and down using the flaps as if there is a direct connect between your arm and the nose position. This is one of my favorite characteristics of the Comanche. Manual flaps with this instant reaction.

Scott.
A2A Simulations Inc.

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AKar
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Re: Pitch angle with gear and flaps

Post AKar »

Scott - A2A wrote:
03 Aug 2020, 08:27
The nose movement is instant and when you grab the flaps, you can rock the nose up and down using the flaps as if there is a direct connect between your arm and the nose position. This is one of my favorite characteristics of the Comanche. Manual flaps with this instant reaction.
I'd love to try that, somehow I've missed all the Pipers with mechanical flaps. Or I've been involved with them more than I care for, Cherokees, Arrows and Senecas mainly, but somehow I've never had a chance to fly one, at least at controls.

Mawingo, I can't really add anything about the gear to what Scott described above. The disturbance of the open gear bays is significant. In some airplanes it is known that if in very critical speed & power condition, retracting the landing gear can, in fact, be a bad idea due to severely increased drag when the gear doors open for retraction sequence. I can't think of any intuitive way of thinking how the gear affect the pitch in general.

On the flaps, one way you can think it is that they almost always act as 'an elevator' when you view the wing alone, hence the natural pitch-down moment when you extend the flaps. But the increased downwash angle interacts with the tailplane as well, introducing pitch-up moment. Depending on the specific airplane configuration, one or another of these effects can be dominant. Some may even have a reversal at some point during the flaps extension (for instance, the first degrees give pitch-up, but extending the flaps fully will begin to introduce pitch-down), but this is highly undesirable.

-Esa

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DHenriquesA2A
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Re: Pitch angle with gear and flaps

Post DHenriquesA2A »

AKar wrote:
03 Aug 2020, 09:12
Scott - A2A wrote:
03 Aug 2020, 08:27
The nose movement is instant and when you grab the flaps, you can rock the nose up and down using the flaps as if there is a direct connect between your arm and the nose position. This is one of my favorite characteristics of the Comanche. Manual flaps with this instant reaction.
I'd love to try that, somehow I've missed all the Pipers with mechanical flaps. Or I've been involved with them more than I care for, Cherokees, Arrows and Senecas mainly, but somehow I've never had a chance to fly one, at least at controls.

Mawingo, I can't really add anything about the gear to what Scott described above. The disturbance of the open gear bays is significant. In some airplanes it is known that if in very critical speed & power condition, retracting the landing gear can, in fact, be a bad idea due to severely increased drag when the gear doors open for retraction sequence. I can't think of any intuitive way of thinking how the gear affect the pitch in general.

On the flaps, one way you can think it is that they almost always act as 'an elevator' when you view the wing alone, hence the natural pitch-down moment when you extend the flaps. But the increased downwash angle interacts with the tailplane as well, introducing pitch-up moment. Depending on the specific airplane configuration, one or another of these effects can be dominant. Some may even have a reversal at some point during the flaps extension (for instance, the first degrees give pitch-up, but extending the flaps fully will begin to introduce pitch-down), but this is highly undesirable.

-Esa
On the Mustang the gear fairing doors create enough drag during a retraction that I have in the past advised pilots doing go-arounds to wait until climb airspeed has been obtained before retracting the gear.

The old Cessna 150's had a Johnson Bar manual flap handle. You could actually create an up and down pitch moment alternating its direction with the release button depressed. Great fun on occasion.
The one thing you didn't want to do was let the handle slip from your grasp. It would slam shut in the up position with a sound like a gunshot that could scare the living daylights out of you. :-)
Dudley Henriques

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AKar
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Re: Pitch angle with gear and flaps

Post AKar »

DHenriquesA2A wrote:
03 Aug 2020, 09:27
AKar wrote:
03 Aug 2020, 09:12
Scott - A2A wrote:
03 Aug 2020, 08:27
The nose movement is instant and when you grab the flaps, you can rock the nose up and down using the flaps as if there is a direct connect between your arm and the nose position. This is one of my favorite characteristics of the Comanche. Manual flaps with this instant reaction.
I'd love to try that, somehow I've missed all the Pipers with mechanical flaps. Or I've been involved with them more than I care for, Cherokees, Arrows and Senecas mainly, but somehow I've never had a chance to fly one, at least at controls.

Mawingo, I can't really add anything about the gear to what Scott described above. The disturbance of the open gear bays is significant. In some airplanes it is known that if in very critical speed & power condition, retracting the landing gear can, in fact, be a bad idea due to severely increased drag when the gear doors open for retraction sequence. I can't think of any intuitive way of thinking how the gear affect the pitch in general.

On the flaps, one way you can think it is that they almost always act as 'an elevator' when you view the wing alone, hence the natural pitch-down moment when you extend the flaps. But the increased downwash angle interacts with the tailplane as well, introducing pitch-up moment. Depending on the specific airplane configuration, one or another of these effects can be dominant. Some may even have a reversal at some point during the flaps extension (for instance, the first degrees give pitch-up, but extending the flaps fully will begin to introduce pitch-down), but this is highly undesirable.

-Esa
On the Mustang the gear fairing doors create enough drag during a retraction that I have in the past advised pilots doing go-arounds to wait until climb airspeed has been obtained before retracting the gear.

The old Cessna 150's had a Johnson Bar manual flap handle. You could actually create an up and down pitch moment alternating its direction with the release button depressed. Great fun on occasion.
The one thing you didn't want to do was let the handle slip from your grasp. It would slam shut in the up position with a sound like a gunshot that could scare the living daylights out of you. :-)
Dudley Henriques
Ha! :) I've flown once an F150J I think, not quite sure about the exact model, but I think it was a Reims-build 150J. The flight was somewhat interesting, as it was completely ad-hoc and the instructor, it turned out later, didn't quite gasp that I had not flown a single piston ever before (only gliders, nor had I checked out the handling of the SEPs in advance) as the flight was not my idea. So he made me do all the piloting. My only flight controls learning recollections from the flight are that a) how great the control forces on a puny 150 can be when left to the landing trim setting for first ever SEP takeoff (yes, I asked about that setting in hopes to confirm), and b) that Cessnas take no rudder with roll. :) The flaps were electrical up/off/down on that one, albeit (IIRC) with non-standard (=malfunctioning) switch that you had to manually center as it didn't self-return. After that takeoff experience, the pitch moment from the flaps, when changing in flight, passed me unregistered. :mrgreen:

-Esa

Mawingo28
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Re: Pitch angle with gear and flaps

Post Mawingo28 »

Thanks to everyone for your replies, all informative and useful. As ever, just loving all the A2A planes I have. Just got a great new computer which really has sorted out FSX with enough head-room on FPS. Considering options for the future, and of course the elephant in the room is the new Microsoft FS... :D

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