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F-5 won't fly level


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Quick question...has anyone been able to trim out the F-5 to fly straight and level? I have tried using the HOTAS (:cry: X-55), the trim works beautifully however, I'm always climbing or descending. I also try to trim with the keyboard (after clearing HOTAS) with the same result. I seem to be able to trim out other A/C...any words of wisdom ??

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There is no AP in the F5, she's still a (cheap;)) hands on stick aircraft to fly. Always trimming or adjusting for altitude with the stick.

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Quick question...has anyone been able to trim out the F-5 to fly straight and level? I have tried using the HOTAS (:cry: X-55), the trim works beautifully however, I'm always climbing or descending. I also try to trim with the keyboard (after clearing HOTAS) with the same result. I seem to be able to trim out other A/C...any words of wisdom ??

 

Yep, as David OC said, the F-5E requires constant trimming. All part of the fun!

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My words of advice would be to ignore the previous 2 replies as they're obviously having reading comprehension issues.

 

 

First person randomly starts talking about auto pilot.

 

 

Second person takes the first peron's statement about continuous trim adjustment literally. Clearly has no idea what a trim is for, if you had to adjust the trim continuously it would be pointless having a trim at all.

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The best I ever managed is a gentle sine wave +/- a few hundred feet at around 30k feet average altitude. Dead level requires a careful balance of attitude, speed and trim, I’ve never got it perfect.

 

Normally I get shot down pretty quickly anyway so it doesn’t matter :-)

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My words of advice would be to ignore the previous 2 replies as they're obviously having reading comprehension issues.

 

 

First person randomly starts talking about auto pilot.

 

 

Second person takes the first peron's statement about continuous trim adjustment literally. Clearly has no idea what a trim is for, if you had to adjust the trim continuously it would be pointless having a trim at all.

 

Difficult to see why you felt the need to come on here and be rude to other posters. Your contributions will always be welcome if they are helpful, but there is no place for rudeness here.

Back on topic, it may have been an exaggeration to say the F-5 needs 'constant' trimming, but it certainly needs a lot more activity on the trim hat than any other DCS module that I know of. Very sensitive to speed/height changes. There have been quite a few threads on this here already.

Perhaps your experience is different. In which case, please give us the benefit of your advice.

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What I do is to get the trim near perfect and then make those small corrections with the stick. Works out pretty well. It wont trim perfectly level, and from what i have seen in vids, that's how it's done IRL.

It takes time to learn the F-5, but after a while it becomes second nature. Reference your surroundings down low as well as your VVI. At altitude you need to more frequently monitor your VVI and altimeter for reference.

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You could also try the "non-linear joystick mode" in Special Options. That seems to help a lot of people.

Also, making tiny throttle adjustments help for trimming out perfectly, to allow for 'hands-off' level flight.

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;3562184']Yeah' date=' you basically just need to play around with the trim a lot as you fly about. just as with any aircraft that doesn't have FBW or AP.[/quote']

 

Not exactly. L-39 has no FBW nor AP, but is a lot more easy to get properly trimmed and fly almost straight and level without your hands on the stick. Moreover, F-5 has got stability augmentation channels while L-39 don't. Nevertheless, F-5 is a lot more difficult to properly trim than the L-39. Maybe F-5 is done such way, I'm not saying there's a bug or ED module is wrong. But it's a matter of fact you have to work more with F-5 trim than many other modules (obviously if you get a-10c and switch AP on you fly straight and level, but that's not the matter of this topic).


Edited by nessuno0505
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Second person takes the first peron's statement about continuous trim adjustment literally. Clearly has no idea what a trim is for, if you had to adjust the trim continuously it would be pointless having a trim at all.

you're not even trying to comprehend what he's saying.

 

here's the deal: air's behavior and the resulting airplane's behavior changes with airspeed. the f-5 has no assistance for compensating with this unlike the carefree trim scheduling that compensates for airspeed variations that the f-15 and fbw aircraft have.

so while yes, for a set constant airspeed, there is a trim that allows for stable level flight, this is a relatively delicate equilibrium point that can be upset by the most minor deviation. any pitch deviation will result in descent or ascent, which results in an acceleration or deceleration, invalidating the originally set trim. likewise, any throttle state mismatch with trim will also result in an upset.

the "problem" is that trim here is graduated in steps, so for your given airspeed, the correct trim angle may be in between two attainable trim steps. theoretically you can set a desired trim angle, and then adjust throttle for equilibrium (no different than the landing technique of aoa for speed, throttle for altitude), though the f-5 in particular has poor spooling and acceleration characteristics that will frustrate this.

 

in other words, true equilibrium state in the f-5 will be practically impossible to obtain. get used to handholding the aircraft.

 

Moreover, F-5 has got stability augmentation channels while L-39 don't.

to my understanding, stability augmentation here does not mean the f-5 has a system that helps you maintain level flight. instead they are limiters to keep aircraft behavior predictable and useful in maneuvers.


Edited by probad
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I can trim it out to fly straightish and levelish enough for me to look down into the pit for a moment and not find myself spiraling into the ground once I look up. In a nimble fighter without FBW I don't expect to fly hands off for any extended period of time. One thing that helped me was to set a small deadzone on my stick - since it's old and somewhat wobbly in the center. See if you don't have that problem.

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Not exactly. L-39 has no FBW nor AP, but is a lot more easy to get properly trimmed and fly almost straight and level without your hands on the stick. Moreover, F-5 has got stability augmentation channels while L-39 don't. Nevertheless, F-5 is a lot more difficult to properly trim than the L-39. Maybe F-5 is done such way, I'm not saying there's a bug or ED module is wrong. But it's a matter of fact you have to work more with F-5 trim than many other modules (obviously if you get a-10c and switch AP on you fly straight and level, but that's not the matter of this topic).

F-5 is by design more unstable. In my opinion DCS does a great job to reflect this difference between the jets.

I can trim it out to fly straightish and levelish enough for me to look down into the pit for a moment and not find myself spiraling into the ground once I look up. In a nimble fighter without FBW I don't expect to fly hands off for any extended period of time. One thing that helped me was to set a small deadzone on my stick - since it's old and somewhat wobbly in the center. See if you don't have that problem.

+1

I think the hardware has a big influence here and might even be the issue. I switched from an old cheap stick to a better and new one. Night and Day.

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I have used the X-55 rhino stick for 2 year + and I have great results flying the F-5E you have to continuously trim for hand off flying ...

There are 2 categories of fighter pilots: those who have performed, and those who someday will perform, a magnificent defensive break turn toward a bug on the canopy. Robert Shaw

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Don't forget that real trim in an AC is designed to minimize the force required on the stick/yoke to easy fatigue while flying for long periods of time. Real world you get the AC level with external reference cues (ie the horizon) in day time (and the instruments at night), and then trim to reduce force on the stick.

 

Real world, you'd level out, trim to something comfortable and make very minor corrections to pitch with the stick almost without thinking about it. Sort of like when you drive, you get in the your lane, and you stay there without having to really think about it. Why do you need to fly hands off for long periods? You're not taking sextant shots, updating charts, etc. You're in a short range high performance fighter.

 

One of the biggest transgressions sim pilots make in real AC (and I know from personal experience) is paying WAY too much attention to the instruments over what's outside the window. If I can see the horizon and we're level do I need to stare at the ADI? Conversely most simmers have little trouble picking up the instrument scan required to fly IFR.

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Looks like a lack of trim resolution to me, either in the DCS version and/or in the real one as well. The DSC F-5 would fly perfectly level IMO if trim resolution would be higher.

 

One click and she immediate very subtle climb (e.g. at 250kts), one click in the other direction and she starts a very subtle descent.

 

I've flown a French GA plane with an all-moving horizontal tail (like the F-5) and it was almost to impossible to trim for level flight for the same reason

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Remember that speed plays a role in trim as well. As you go faster, the more exaggerated the aircraft response will be to control inputs. Ask someone who's flown a T-38 how much of a pain in the ass it is to trim for level flight at high mach numbers. I suggest slowing to 350-400KIAS at around 15,000 and practicing basic aircraft handling drills to include trimming for level flight. Try some 30 degree level turns, steep turns, vertical S etc. Slow down and configure and practice some traffic pattern stalls and the like. These full fidelity modules are really pretty good and you need to get a feel for the airplane before you try and employ it.....just as you would in real life. Once you get used to the F-5, she really flies pretty sweet.

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I suggest slowing to 350-400KIAS at around 15,000 and practicing basic aircraft handling drills to include trimming for level flight.

Well, (at least) I can't even trim the F-5 for level flight at an even lower 250kias.

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;3567623']1.Trim isn't supposed to act as an altitude AP, you're supposed to fly the plane...

2.The purpose of trim is to make flying easier on the pilot

1.In calm air I haven't encountered an airplane IRL that can't be trimmed for level flight. If it's only a few seconds. On the DCS F-5 it's either a tad too much nose up, or a tad too much nose up.

2.There's a whole lot of airplanes which couldn't be flown at all without trim ;)

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Remember that speed plays a role in trim as well. As you go faster, the more exaggerated the aircraft response will be to control inputs. Ask someone who's flown a T-38 how much of a pain in the ass it is to trim for level flight at high mach numbers. I suggest slowing to 350-400KIAS at around 15,000 and practicing basic aircraft handling drills to include trimming for level flight. Try some 30 degree level turns, steep turns, vertical S etc. Slow down and configure and practice some traffic pattern stalls and the like. These full fidelity modules are really pretty good and you need to get a feel for the airplane before you try and employ it.....just as you would in real life. Once you get used to the F-5, she really flies pretty sweet.

 

Weight as well.

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This is a question I have often thought on too and recently I had an opportunity to query this with a retired F5 driver.

 

He had no prior knowledge of ED and DCS so I showed him a youtube video on my phone as part of the explanation and it seemed to grab his attention positively. I wanted to communicate to him that my query had a background other than curiosity.

 

Anyway, his general reply about trim in the F5 was that you could trim it well though it is always a hands on plane to fly.

 

This is no formal testimonial obviously and merely anecdotal of course but it marries well with my own sim experience of the DCS product. (I use a Warthog which is in good condition). I can trim the DCS F5 well but not to the extent that I can forget about it. I am hands on always too. :smilewink:

 

S!

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Looks like a lack of trim resolution to me, either in the DCS version and/or in the real one as well. The DSC F-5 would fly perfectly level IMO if trim resolution would be higher.

 

One click and she immediate very subtle climb (e.g. at 250kts), one click in the other direction and she starts a very subtle descent.

 

I've flown a French GA plane with an all-moving horizontal tail (like the F-5) and it was almost to impossible to trim for level flight for the same reason

 

 

You're right Bbrz!

 

The DCS model does NOT agree with actual airplane behavior in terms of pitch (and other things I would say).

 

At the time of its launch I tried to contact belsimtek but despite having 33 years of (real) flying myself, I was ignored. Here at the Forum I only mentioned 2x but I do not have the time and patience to be arguing with people who have no real flight experience and think they are the masters.

 

Unfortunately I do not have a real footage of the F-5, but try Youtube and you'll see that the plane is stable and not this "up & down" IVSI that you see in DCS model.

 

There are multiple videos (Youtube), look for "F-5 Low Level" among others, and you'll see that you´re right.

 

Best Regards!

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This is a question I have often thought on too and recently I had an opportunity to query this with a retired F5 driver.

 

Anyway, his general reply about trim in the F5 was that you could trim it well though it is always a hands on plane to fly.

 

This is no formal testimonial obviously and merely anecdotal of course but it marries well with my own sim experience of the DCS product. (I use a Warthog which is in good condition). I can trim the DCS F5 well but not to the extent that I can forget about it. I am hands on always too. :smilewink:

 

S!

 

You're right Bbrz!

 

The DCS model does NOT agree with actual airplane behavior in terms of pitch (and other things I would say).

 

Unfortunately I do not have a real footage of the F-5, but try Youtube and you'll see that the plane is stable and not this "up & down" IVSI that you see in DCS model.

 

There are multiple videos (Youtube), look for "F-5 Low Level" among others, and you'll see that you´re right.

 

Best Regards!

 

This aircraft being a Mach+ fighter design with no AP or FBW and only has dampening would be a very hands on aircraft. One video I saw that's 360 view on youtube so you can look at the stick, it's not very stable flying video tho. Still you could see lots of movement with the stick the whole time.

 

Could this also come down to not having a good stick?

 

Real world, you'd level out, trim to something comfortable and make very minor corrections to pitch with the stick almost without thinking about it. Sort of like when you drive, you get in the your lane, and you stay there without having to really think about it.

 

Perhaps this needs to be made easier to trim / hold level for our crap controls? Still waiting to get my Gunfighter pro VKB!!:cry: That stick with dampening and large throw would be a good test for this aircraft. I will look for that video when home, it's the one from takeoff to landing.


Edited by David OC

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