Saitek HOTAS rudder operation doesn't work correctly.. HELP!
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The F-16 is fly by wire, you are told not to touch the rudder in flight by the air force. Only to purposely get the plane to go uncoordinated. It will fly nothing like a rc plane or a cessna, those are stable planes that need no computer corrections. In the f-16 you fly G commands, not pitch unless in refuel mode or landing configuration. The rudder will not do what you want because of the Aeileron-Rudder-Interconnect in the F-16. You are flying the exact flight control computer law code with the nasa flight model used to help develop some of the code in bms. Real F-16 pilots worked on the flight model, and Real fighter pilots work on BMS.
The f-16 is impossible to fly without the computer, it has Relaxed Static Longitudinal Stability, which means you’ll screw up continuously without the computer correcting the flight path.
Your RC F-16 almost certainly was not in the same stability profile as the real f-16, unless it had an onboard computer correcting everything, which should be expensive and heavy, or it would not survive the takeoff.
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Murphy - I promise you, it’s correct. I could demonstrate the same effect in a real airplane. Nothing more I can say!
I think I understand what you are referring to and I think we’re talking apples and oranges… So let me clear it up a bit.
If the flight model is correct, why can’t I perform a flat turn? When I apply left rudder (verified in chase view) and enough right aileron to keep the aircraft level, it flies in a straight line… In a real aircraft, it should be performing what is called a flat turn… The plane should be turning while the wings remain level. This is a very basic air maneuver that every aircraft I know of can perform…
I should clarify that the aircraft does in fact turn, but the rate of turn is so slow it would take about 10 minutes to complete a full circle. There’s either something wrong with my PC, or something wrong with the flight model.
Try it yourself… Keep your wings and nose level and try to make a flat turn…
Guys, I’m not some newbie kid who picked up a play station substitute and doesn’t understand how to fly… I may not be a real FAA licensed pilot either but basic aircraft maneuvers are not rocket science… If I was complaining that I couldn’t perform a tail slide (in an f16! LOL), or that it didn’t act right in a flat spin, or something of that nature, that would be different… But a flat turn is a very basic thing… and it won’t do it. Maybe my explanation has cleared up what I’m talking about?
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The F-16 has a rudder which is a lot smaller than the wings. You flat out cant develop a serious yaw rate in the jet using the pedals. It just plain doesnt work that way.
The explanation has cleared up what you mean. The answer is still that you dont turn a fighter jet with the pedals.
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F-16 controls command pitch, yaw, and bank which is not the same as elevator, rudder, and aileron. If you input yaw into the jet and develop beta angle that’s a change of heading but not one of course. Releasing yaw input resumes the normal FLCS program of minimizing beta and I wouldn’t be surprised to see the FLCS command counter rudder to reduce beta faster than natural weathervaning.
I don’t think you appreciate quite the level of depth the flight model is made to. One can do a relatively simple aerodynamic analysis based on the tail surface, rudder surface, rudder deflection, tail to CoP distance, etc. and find the sustained beta angle corresponding to full deflection are various airspeeds. It’s not going to be much. In fact the “knife edge pass” the Thunderbirds do requires significant rudder (close to 100%) to maintain lifting beta at 90AOB, that’s got to be good for at least 5-10 degrees beta to not fall.
Any simple airplane will rubber band to reduce beta when rudder is neutralized. If you imagine a plane on a pivot in a wind tunnel and you nudge some beta into it it will resume zero beta over time due to positive longitudinal stability. Not only will the F-16 diminish beta with neutral rudder by aerodynamics but it might very well seek it more aggressively.
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Verified… something definitely wrong somewhere.
Hi there and welcome,
Am I reading this thread correctly, in that you are expecting the F-16 flight profile to be similar/same as that of a Cessna 172, and calling the flight model in-sim as incorrect as a consequence?
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I think I understand what you are referring to and I think we’re talking apples and oranges… So let me clear it up a bit.
If the flight model is correct, why can’t I perform a flat turn? When I apply left rudder (verified in chase view) and enough right aileron to keep the aircraft level, it flies in a straight line… In a real aircraft, it should be performing what is called a flat turn… The plane should be turning while the wings remain level. This is a very basic air maneuver that every aircraft I know of can perform…
Don’t think so, jets like the F-4 actually snap rolled with rudder……that was the only safe way to bank it at certain speeds/AOA.
I should clarify that the aircraft does in fact turn, but the rate of turn is so slow it would take about 10 minutes to complete a full circle. There’s either something wrong with my PC, or something wrong with the flight model.
Try it yourself… Keep your wings and nose level and try to make a flat turn…
Guys, I’m not some newbie kid who picked up a play station substitute and doesn’t understand how to fly… I may not be a real FAA licensed pilot either but basic aircraft maneuvers are not rocket science… If I was complaining that I couldn’t perform a tail slide (in an f16! LOL), or that it didn’t act right in a flat spin, or something of that nature, that would be different… But a flat turn is a very basic thing… and it won’t do it. Maybe my explanation has cleared up what I’m talking about?
Ever heard the saying assumption is the mother of all **** ups?
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First, if available, install the drivers from Saitek. You will get better functionality of your hardware. When you use the rudder in flight, it will respond somewhat slowly, causing a small amount of a roll, depending how long and hard you hold the yaw input, but mostly yaw. When you release it, it will act as if you are on a spring, and the aircraft will return back to yaw-less flight. This is normal. I don’t believe the old version of Falcon did that, which was not a correct modeling of the aircraft. Falcon improved with Falcon 4.0, and has improved with every modification up to where we are now, 4.32. One other thing, try releasing the rocker in steps or with a gradual release back to center. See if it centers more smoothly. If it doesn’t, it could be the drivers, or the rocker may not have that ability. The rocker probably only has two switches and release immediately when you start releasing the rocker. If you want more accurate Rudder/NWS operation, try the Saitek Rudder Pedals. They work great, and you will have toe brakes :).
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Out of morbid curiosity I tested what a wings-level rudder only turn looks like in Falcon BMS. The F-16 absolutely will flat turn at a rate of 0.85 degree per second of heading change at 250-300 knots with an established beta angle of about 4 degrees. Doing a bit of V^2/R physics that’s about a 0.3g turn radial component.
As for the “it resumes flying straight if I get off the rudders” I dunno what to tell you. That’s what Cessna 172s do too.
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…what Fredrf says…+1.
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I think I understand what you are referring to and I think we’re talking apples and oranges… So let me clear it up a bit.
If the flight model is correct, why can’t I perform a flat turn? When I apply left rudder (verified in chase view) and enough right aileron to keep the aircraft level, it flies in a straight line… In a real aircraft, it should be performing what is called a flat turn… The plane should be turning while the wings remain level. This is a very basic air maneuver that every aircraft I know of can perform…
I should clarify that the aircraft does in fact turn, but the rate of turn is so slow it would take about 10 minutes to complete a full circle. There’s either something wrong with my PC, or something wrong with the flight model.
Try it yourself… Keep your wings and nose level and try to make a flat turn…
Guys, I’m not some newbie kid who picked up a play station substitute and doesn’t understand how to fly… I may not be a real FAA licensed pilot either but basic aircraft maneuvers are not rocket science… If I was complaining that I couldn’t perform a tail slide (in an f16! LOL), or that it didn’t act right in a flat spin, or something of that nature, that would be different… But a flat turn is a very basic thing… and it won’t do it. Maybe my explanation has cleared up what I’m talking about?
no, all real planes do not perform what you call “flat turns”.
and no you are completely mistaken if you think a FLat turn is a basic thing…the result of this manoeuver can be very different from on AC to another (because it implies roll /yaw coupling , fuselage shadowing, aileron Adverse yaw, diedhral effects …), and this is even worse when FLCS and ARI comes into play
Reference is made to :
Talking “only” about LAteral Lift that would provoke a flat turn (in combination with a rotation around Z axis, but i wont develop it here) , It all depends on many parameters :
See Y axis force coefficient Page 38 :
- Lateral Lift of Tail and fuselage
- Lateral Lift induces by Ailerons (that are used to counteract Rudder Roll)
- Lateral Lift induced by TEF
- Lateral Lift induced by Roll rates and yaw Rates (which are nulled in case of trying to perform your manoeuver)
all those parameters depend on AOA and BETA (side slip angle)
you can even have an opposite effect , which can be conter intuitive.
For instance, look at
The Lift Generated by the side slip angle is Page 72, is the Lateral Lift coefficient at 30 deg Rudder for Alpha , beta angles.
As you can see, the chart if not symmetrical around the Beta Angle (side slip). For instance at Beta +6 deg, the force is still positive while your intution would tell you that it should be negative.
Then, of course, when you apply aileron to counteract the Rudder Induce roll, there is an effect on the lateral Lift, this is the CY delta a,20 page 70.
AS you can see, the order of magnitude of the LAteral Lift generated by side slip and lateral lift generated by ailerons are the same order of magnitude… (sign is opposite since you should put delta a -20 to counteract a positive Delta R rudder action).
So that means that the lateral force is small when trying to perform a flat turn on F16…so the turn will be very slow
BESIDES , one important parameter :figure 13 page 36 , the F16 is very sensitive with adverse roll control.
In order to avoid reverse roll commands, the ARI controls the rudder to avoid it.
ARI is very active when you try to perform your Flat Turn which greatly reduces the influance of the rudder… (and that is why you dont developp a side slip angle of 25 deg but much more limited)
I could explain in many details why the F16 does not perform a “flat” turn like at high rate you think a scale AC does , but it will require me many hours of writing and i am not even sure people will understand me …
Seeing the different Aerodynamics parameters, a flat turn manoeuver will more likely result in a limited side slip manoeuver rather than a “turn”…but as i said, the F16 has assymetric airframe so one side should give slight different results from the other for those who like testing, you can test that one
AS a conclusion : the F16 is not a scale model and yes his behavior is very very closely simulated in BMS.
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And btw, ALL aircraft in the world that i know are stable in Yaw.
That means that AC will have an opposite response to AOBeta , which means that the tail will come back as soon as you release rudder.
This spring movement can be more or less dampened with rudder control in order to avoid oscillations and Dutch Rolls…. but yes all AC in the world are Stable in YAW … even RC ones …
I can make a video of my RC sim if you want …because i fly RC Ac and Helos as well for my RC training
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Thanks for all the replies… Looks like I’m going to have to be reeducated…
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…I happen to know for a fact that pylons are de-stabilzing in yaw, and that swept wing aircraft in particular are subject to roll-yaw coupling…this being one of the more violent examples I can think of:
Yes, you need to re-think your definition of “stable”…particularly when it comes to fighter aircraft - stable = not maneuverable. Most small tactical aircraft (i.e.; fighters) are designed to be neutral, and in the case of fly-by-wire - augmented into “stability”. It is possible to drive them into odd points in the control laws…like in this video.
BTW - I was on-station when this departure happened. It was a test demo for a Blue Angels chained roll series. Was quite the talk for a bit.
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Actually, making them neutrally stable is only something that came into being along with FBW stevie.
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I guess what I meant to point out is that most (if not all) fighters are “relaxed” in regard to being stable - in that any fighter of any generation is less “stable” than any commercial or recreational aircraft designed for a mission where less maneuverability or agility is required and safety is the larger consideration. And I’m talking in terms of static stability…dynamic stability and performance is a separate topic/discussion.