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Rudder effectiveness


bkthunder
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This seems to be a constant problem with BST fixed wing modules.

As in the F-15, also the F-86 presents the same strange behavior by which the rudder will only change the heading of the aircraft without changing the track (that is, the actual trajectory of the aircraft over the ground).

It also means that rudder only works to put the aircraft in a side slip and nothing more, if you release the pedals, the nose will center and no change of heading has been obtained.

 

Any word on this? Will it get fixed?

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This seems to be a constant problem with BST fixed wing modules.

As in the F-15, also the F-86 presents the same strange behavior by which the rudder will only change the heading of the aircraft without changing the track (that is, the actual trajectory of the aircraft over the ground).

It also means that rudder only works to put the aircraft in a side slip and nothing more, if you release the pedals, the nose will center and no change of heading has been obtained.

 

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Something like this has consequences over the whole flight model IMO, because it's not calculating elements such as the fuselage, the local AoA of the tail fin etc.

should be highest priority but we haven't seen any improvements on that side for the f-15 either, which has been released a few patches ago... Not holding my breath tbh, but it's a bit of a shame because the rest of the module seems really fine...

Windows 10 - Intel i7 7700K 4.2 Ghz (no OC) - Asus Strix GTX 1080 8Gb - 16GB DDR4 (3000 MHz) - SSD 500GB + WD Black FZEX 1TB 6Gb/s

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Something like this has consequences over the whole flight model IMO, because it's not calculating elements such as the fuselage, the local AoA of the tail fin etc.

should be highest priority but we haven't seen any improvements on that side for the f-15 either, which has been released a few patches ago... Not holding my breath tbh, but it's a bit of a shame because the rest of the module seems really fine...

 

I concur this should have top priority on the next patch, a hotfix would be even better. :thumbup:

 

 

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Dude......I don't think I'd post something like that if my wife weren't able to process that kind of a question.

Not to insult you but really??????

 

Ya I wouldn't either if it was my wife.

 

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I'd rather have a bottle in front of me than a frontal lobotomy and I've had both.

 

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  • 2 weeks later...
I concur this should have top priority on the next patch, a hotfix would be even better. :thumbup:

 

Yes. The F-86 has dropped to the bottom of my fly list for this reason. Too bad, I love the plane and it's fun to fly.

 

Wow never noticed that, but now I have done a test flight & it's true.

This should have high priority indeed!

 

I love Belsimtek for their F-86 and F-15, but I hope this problem is one of their top priorities...

 

Yep, it's actually surprising. Such an elementary thing, and something that no other aircraft shows.

 

My thoughts exactly.

Guys, can anyone explain to me - in layman's terms - what exactly you think is wrong with the F-86F rudder? What exactly makes you think course change rate with rudder is not enough? Please consider that not all aircraft are very affected by the rudder. I am not saying you are wrong, but does anyone of you have evidence or hard data to backup the claim (for example aircraft performance records like the "steady state sideslip test")?

 

I think we can probably expect some flight model and aerodynamics fine-tuning after MiG-15 release.

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Guys, can anyone explain to me - in layman's terms - what exactly you think is wrong with the F-86F rudder?

 

Certainly: I expect, when I apply considerable rudder and keep wings level with ailerons, that my course should perceptibly deviate. It doesn't.

 

What exactly makes you think course change rate with rudder is not enough?

 

Because I can barely even notice it when I apply FULL rudder. I don't have data, but in the sim currently, in my submission, rudder turns are completely impossible for any practical purpose. You can't line up approaches, etc.

 

Please consider that not all aircraft are very affected by the rudder.

 

Again, I don't have any charts (couldn't find any) regarding what the performance should be like, so take this with a pinch or two of salt, but surely this can't be right.

 

Further, considering that the F-15 would seem to have the same issue, it becomes more likely to me that BST's FM is a bit off in this area.

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I think we can probably expect some flight model and aerodynamics fine-tuning after MiG-15 release.

 

What does the Mig-15 have to do with work on the F-86?

 

EDIT: Btw, if the rudder, correctly, has so little effect in level flight then how does it perform it's function in a turn?


Edited by cichlidfan

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Certainly: I expect, when I apply considerable rudder and keep wings level with ailerons, that my course should perceptibly deviate. It doesn't.

 

Precisely this.

 

Derelor, do the following experiment: with the A-10C, while flying at a moderate speed, gradually apply full rudder, using the ailerons to prevent the aircraft from banking. The aircraft, slowly but surely will perform a flat turn. This kind of behavior is to be expected from pretty much any aircraft in the world.

 

Now do the same experiment with F-86 (also F-15 if you want) - the aircraft in this yawed state keeps flying straight. Very weird.

 

I might be wrong, but I think what's missing from the flight model for F-86 and F-15 is the sideforce produced by the fuselage in a yawed state.

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I think the problem is from my testing is that the deflection of thrust is not added to the vv, as such, the aircraft flys with out turning because the aircraft still thinks its level. maybe some of the restoring forces are also not acting on the aircraft which would also help it turn in a level rudder turn like this. but I dont know too much about the math behind it.

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I have not yet tested this, but if it is true, then something is significantly wrong with the flight-model.

 

For example, if you yaw the airplane to the left, then the engine exhaust will be pointed slightly to the right (in comparison to the original flight path). That means that thrust will keep pushing the aircraft forward, but a small fraction of the engine power will also push it to the left. So the aicraft should at least slightly translate to the left.

 

Or does it at least slightly translate to the sides when rudder is applied?

 

edit: Just tested it. The plane deflects in either direction only about 8° and as soon as the rudder is set to neutral it jumps back zo 0° deflection. The plane actually keeps turning veeery slowly when full rudder is applied.

My theory: There is no lack of a force like fuselage sideforce but there is actually a force that tries to push the plane back into 0° yaw. It becomes stronger the greater the deflection is, and at +-8° it becomes greater than the force caused by the rudder.

 

edit edit: Imagine it like there is a force that tries to turn the aircraft *into* the wind.


Edited by Viersbovsky

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What does the Mig-15 have to do with work on the F-86?

 

EDIT: Btw, if the rudder, correctly, has so little effect in level flight then how does it perform it's function in a turn?

 

The Sabre is such a stable aircraft that you generally need pretty much zero rudder to stay coordinated.

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Thank you all for your input. As Sobek mentioned, the issue is already reported to the devs (ticket #27979).

 

It's unfortunate though that we cannot provide hard data that show either the exact function or individual data points for course deviation during rudder input. Please let us know when you stumble upon a relevant source.

It's just one of those moments in testing when you feel something is not right, but cannot specify/quantify/proof it - probably no one here knows _exactly_ how it should behave in the F-86F-35.

 

@cichlidfan:

What I meant is that maybe availability of the MiG-15 and the ability to compare both MiG-15 and F-86 flight models will allow further fine-tuning.

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Thank you, too. I found the dash-1 but it had no charts of this. It did have this:

 

http://aviationshoppe.com/manuals/f-86_flight_manual/f-86.html

 

Sect VI, p. 7

 

YlNjqU7.png

 

Nothing substantive, but it feels like they'd mention if the plane was extraordinarily insensitive to rudder turns.

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