Flaps Always at 5

[104th_Maverick]

Taken from NATOPS FLIGHT MANUAL NAVY MODEL AV--8B/TAV

 

 

Cheers! I'll forward this on to the dev team and see what they come back with.

[rinao0o]

When auto flaps are turned on, flap angle does not come lower than 5 degrees unless the plane is getting into transonic regions. The angle starts to drop below 5 degrees when mach number exceeds 0.88, and completely retracts only when Mach number exceeds 0.95.

 

For more details refer to page 2-50, A1-AV8BB--NFM--000.

Edited December 5, 2017 by rinao0o

[dresoccer4]

thanks for all the responses everyone!

 

so i wonder now if the standard operating procedure is to turn the flaps to the "Off" position when in long-distance cruise mode to get the flaps to 0 degrees?

[GinGin]

Very instructive, thanks for the explanations of transonic flaps behavior

[Flamin_Squirrel]

thanks for all the responses everyone!

 

so i wonder now if the standard operating procedure is to turn the flaps to the "Off" position when in long-distance cruise mode to get the flaps to 0 degrees?

 

I don't think so. The performance manual makes limited reference to flap setting, and where it does, it only seems to reference the auto setting (for cruise).

[dresoccer4]

I don't think so. The performance manual makes limited reference to flap setting, and where it does, it only seems to reference the auto setting (for cruise).

 

hmm, if this is the case, then i wonder what the logic is for this? doesn't seem to make sense to fly with your flaps down over long distances. i can't think what the advantage would be

[M1Combat]

It will be interesting to see what standard procedure is but...

 

I just turn the setting to off when heading to the AO and then back to cruise when I get there. When I forget and drop one of fourteen MK82's then attempt the CAS turn I know real quick :).

[Eldur]

I might have found something about this. Check the flaps shape here.

 

And there's been a discussion about it over here. Apparently the flaps are 5° up at 0° setting, most probably to counter some transsonic nose down tendencies. Why else should they go up in a speed range from M .88 to .95?

 

 

 

So I just would guess that at 5°, which is the cruise setting and auto setting at most speeds, the drag would be minimal. Now we just need some confirmation on this one since we can't have a simulation modeled on wild guesses. But that would make sense, simply because you'd expect cruise setting to be min. drag after all.

[Luzifer]

We're already at four pages of obsessing over a number... And it's just that, a number.

 

So it looks like the designers decided to define 0 = uppermost position of flaps which leaves neutral position = 5. They could have just as well decided neutral = 0 and uppermost = -5 like other planes, but they didn't. Neither is more wrong or right than the other, where you put the zero is just a matter of conventions and definitions.

 

Meaning, of course, that when you force the flaps to 0 where they shouldn't be, you're going to get more drag (higher AoA for same lift, also higher fuselage AoA).

[Rlaxoxo]

We're already at four pages of obsessing over a number... And it's just that, a number.

 

So it looks like the designers decided to define 0 = uppermost position of flaps which leaves neutral position = 5. They could have just as well decided neutral = 0 and uppermost = -5 like other planes, but they didn't. Neither is more wrong or right than the other, where you put the zero is just a matter of conventions and definitions.

 

Meaning, of course, that when you force the flaps to 0 where they shouldn't be, you're going to get more drag (higher AoA for same lift, also higher fuselage AoA).

 

What are you talking about mate?

I'm so confused, nothing you said makes any sense ...

[robmlufc]

What are you talking about mate?

I'm so confused, nothing you said makes any sense ...

 

 

It takes a few readings but he makes a valid point.

 

5 is where the flaps should be for conventional straight and level flight. Accept it, it's modelled correctly and that's how the jet is. 0 is when you're going mach 0.fast Probably due to stress as much as anything.

 

The GR7/9 has an emergency manual retract which forces the flaps up against their stops, 0. But it's for emergencies, as the name suggests.

[Luzifer]

What are you talking about mate?

I'm so confused, nothing you said makes any sense ...

 

This thread is titled "Flaps Always at 5" and it's pages of discussion of how to avoid having flaps in the cruise setting while in cruise. Does that help?

[dresoccer4]

I might have found something about this...

 

So I just would guess that at 5°, which is the cruise setting and auto setting at most speeds, the drag would be minimal. Now we just need some confirmation on this one since we can't have a simulation modeled on wild guesses. But that would make sense, simply because you'd expect cruise setting to be min. drag after all.

 

good diggin'. i'm sure there is logic behind it all somewhere.

all i know is when i'm throttled back, cruisin at altitude, and i turn flaps "off" to 0 degrees, i speed up quite a bit. so there is definitely a little drag with the normal 5 degree cruise setting. quite the mystery!

 

to the other commenter. it's not just "just a number". it's a physical part of how the plane flies that actually affects things. part of the fun of learning these new systems is figuring out how they work and why they work. attention to detail is what makes DCS so great, and why we all love it!

 

:thumbup:

[mkiii]

Think this is bad. Wait until they realise the ailerons have a droop.. and we can't measure or change the angle, or set when it happens. Where will it all end? ;)

[CoBlue]

This thread is titled "Flaps Always at 5" and it's pages of discussion of how to avoid having flaps in the cruise setting while in cruise. Does that help?

 

This discussion is also about the interest in design & aerodynamic reason for flaps 5 in cruise.

 

McDonnell Douglas extensively redesigned the earlier AV-8A to create the AV-8B & made a whole new wing among other improvements.

So the question is why is it more beneficial to cruise with flaps 5 then 0? Especially since it was a new wing design & they could have omitted the 0 position at all & had free hands to re-design the new wing.

[Eddie]

There is an issue here. While the flaps should at 0 degrees when 5 degrees is indicated in the cockpit at present in DCS that is not the case. If you take a look at the external model (and assuming the 3d model matches what the flight model is doing) 5 degrees cruise position has the flaps deflected 5 degrees down, not at zero.

 

Also at no point do the flaps deflect to the 5 degrees up position.

 

It's also impossible to fly the aircraft to match the climb and cruise speeds etc without setting the flaps to off and thereby forcing them to zero degrees, So it seems like this is a case of misinterpretation of the system by Razbam.

[Kayos]

when i'm throttled back, cruisin at altitude, and i turn flaps "off" to 0 degrees, i speed up quite a bit. so there is definitely a little drag with the normal 5 degree cruise setting. quite the mystery!

:thumbup:

 

I've been turning it off while cruising too. You get more speed and i'm sure it uses less fuel because of less drag.

[Aries144]

CptSmiley,

 

Please accept our sincerest thanks and pass them along to your crew!

 

Bang up job sir! Do you guys ever stop to eat?! ;)

[javelina1]

Gotta code through meals :)

 

Nice! :thumbup:

[mvsgas]

There is an issue here. While the flaps should at 0 degrees when 5 degrees is indicated in the cockpit at present in DCS that is not the case. If you take a look at the external model (and assuming the 3d model matches what the flight model is doing) 5 degrees cruise position has the flaps deflected 5 degrees down, not at zero.

 

Also at no point do the flaps deflect to the 5 degrees up position.

 

It's also impossible to fly the aircraft to match the climb and cruise speeds etc without setting the flaps to off and thereby forcing them to zero degrees, So it seems like this is a case of misinterpretation of the system by Razbam.

 

Not sure if I follow you eddie, why would zero flap in the cockpit be 5° of the flaps? Reading the manual (A1-AV8BB-NFM-000) page 2-46, paragraph 2.15.1

2.15.1 Flaps

The electro--hydraulic operated trailing edge flaps (see Flap System foldout) are controlled by a dual channel electronic flap controller, a dual system hydraulic control valve and two dual tandem actuators. Flap positioning is provided by the flap controller in accordance with switch selection by the pilot. A STOL mode(25° to 62°), an AUTO mode (0° to 25°), and a CRUISE mode (5°) may be selected. Two cockpit switches, an air data computer, a landing gear down relay, a WOW relay, dual sensors on the engine nozzles, and dual sensors on the flaps, provide control inputs to the flap controller. Dual output commands to the hydraulic module control two hydraulic sources to two dual tandem hydraulic cylinders. Engine nozzle and flap positions are shown on the HUD. Flap position is also displayed on the flap position indicator. Nozzle position is also displayed on the engine performance indicator (EPI). The flap controller uses two electric inputs to provide two separate channels for flap control.

 

[ATTACH]174096[/ATTACH]

[Eddie]

It seems from the research done by others posted in this thread that the physical flap angle and the indicated flap angle are not the same. So an indicated angle in the cockpit of 5 degrees actually equates to a physical position of 0 degrees, and an indication of 0 degrees is a physical flap position of +5 degrees (ie the flaps are angle upwards, perhaps to counter transonic pitch moment).

 

Now I don’t know for sure that is the case, but it makes sense.

[Britchot]

They are referred to as reflex or negative flaps:

 

https://www.google.com/amp/www.planeandpilotmag.com/article/the-logic-of-flaps/amp/

Contrary to what you might think, some types of wings can actually benefit from a reflex or negative flap setting. Maule used to equip its airplanes with a negative or reflex flap position.

The company claimed an extra three to five knots with the flaps in the -5 degree position. That's five degrees above a streamlined wing attitude. If that seems counter-intuitive, I've seen it work intermittently on Maules and fairly consistently on Dick VanGrunsven's RV series of homebuilts, adding two-three knots to cruise speed. No, it won't work on a Bonanza/Mooney/Malibu/Cessna 210/etc. The effect is totally dependent on the type of airfoil employed.

[dresoccer4]

interesting change with this. with the latest update, it seems you can no longer retract your flaps to 0 degrees. if you turn your flap power to "off" setting, the flaps stay at 5 degrees and the master warning light comes on.

 

upon close inspection, it looks like 5 degrees IS all of the way up now

Edited December 15, 2017 by dresoccer4

[Kayos]

interesting change with this. with the latest update, it seems you can no longer retract your flaps to 0 degrees. if you turn your flap power to "off" setting, the flaps stay at 5 degrees and the master warning light comes on.

 

upon close inspection, it looks like 5 degrees IS all of the way up now

 

Weird. I wonder if that is intended. You get so much more speed when we could turn it off.

[dresoccer4]

Weird. I wonder if that is intended. You get so much more speed when we could turn it off.

 

agreed. however i may be mistaken, but i mean when i actually visually inspect the plane with flaps at 5 degrees, they look all of the way up like before when they were at 0. need someone else to confirm before i'm certain though..