Will the FBW with C* law be implemented ? - Page 3 - ED Forums
 


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Old 08-21-2019, 08:27 AM   #21
mvsgas
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why would he need rudder trim ? ASYMETRICAL Loads ?
No clean aircraft AFAIK. It needs trim like any other aircraft in all axis.

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if it tries to maintain 1G, then it should be flight path stable in certain conditions
In certain conditions, but does not mean the aircraft auto trims.

For example: Lets say the pilot set up pitch at "X" G at "Y" speed, changing that speed might affect the aircraft, making it climbs or descends. FLCC will not correct roll or yaw, when speaking within the confines of trim level flight.
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Old 08-21-2019, 08:59 AM   #22
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Here, the aircraft appear to be Luke AFB Block 42 after CCIP (JHMCS video), at around 14:40 the pilot give control to the guy on the back seat ( not a pilot, guy is just getting a incentive flight) He tell him to pull power back, note that when speed drops the aircraft starts to descend.

When speed increases, note the aircraft starts climbing. Unfortunately, like all videos it lacks a lot of details and you can't see if the pilots had anything to do with the behavior.

At 20:16, the pilot does a 4 point roll, note how the nose drops.
At 26:00, the guy on the back mention how it leans to the right, and the pilot answer that he will trim it to correct it.
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Old 08-21-2019, 09:03 AM   #23
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You need to trim only the elevators on an aircraft in normal operations, unless you have a fuel, leak, misile fired... resulting in an unbalance aircraft.
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Old 08-21-2019, 09:16 AM   #24
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You need to trim only the elevators on an aircraft in normal operations, unless you have a fuel, leak, misile fired... resulting in an unbalance aircraft.
Not sure what you trying to say, could you explain?
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Old 08-21-2019, 09:25 AM   #25
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Not sure what you trying to say, could you explain?
normally your aircraft is symetrically loaded and assuming its not a turboprop, you only need to trim the elevators except if it has autopitch trim like the A320 and above family.

Why would you need to trim the aileron or rudder ? unless you have one engine failure, asymetrical load, fuel leak....


I didn't understand why the F16 pilot needed to rudder trim his f16
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Old 08-21-2019, 09:35 AM   #26
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Originally Posted by cmbaviator View Post
normally your aircraft is symetrically loaded and assuming its not a turboprop, you only need to trim the elevators except if it has autopitch trim like the A320 and above family.

Why would you need to trim the aileron or rudder ? unless you have one engine failure, asymetrical load, fuel leak....


I didn't understand why the F16 pilot needed to rudder trim his f16
Because the FBW will not correct yaw or roll trim. Every F-16 flies a little different so it will need trim to fly straight.
Also, note on the second video I posted, the aircraft descends all the way to 17520 at around 1g and then climbs all the way to 18000 at around 1g.

So the pitch trim being G commanded in the F-16, meaning you trim by the amount of G you want on the aircraft, the F-16 will not maintain a specific flight path by it self unless re-trim to a different G. Hope that make since.
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Old 08-21-2019, 10:26 AM   #27
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i don't understand,

I dont undertand why all combat aircraft are nt flight path stable with auto timming, would make maneuver easier.

because unlike a commercial aircraft, you are always at not constant speed, meaning that you will need to trim every time
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Old 08-21-2019, 01:33 PM   #28
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Originally Posted by mvsgas View Post
Because the FBW will not correct yaw or roll trim. Every F-16 flies a little different so it will need trim to fly straight.
Also, note on the second video I posted, the aircraft descends all the way to 17520 at around 1g and then climbs all the way to 18000 at around 1g.

So the pitch trim being G commanded in the F-16, meaning you trim by the amount of G you want on the aircraft, the F-16 will not maintain a specific flight path by it self unless re-trim to a different G. Hope that make since.
basically it should be similar to C* in Airbus aircraft, where it is specifically written in the manual that in pitch the control inputs are made to alter the flight path NOT to hold it.
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Old 08-21-2019, 02:51 PM   #29
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basically it should be similar to C* in Airbus aircraft, where it is specifically written in the manual that in pitch the control inputs are made to alter the flight path NOT to hold it.
yes so that means when the stick is released, the Flight path is maintained (in certain conditions of course), it wont be able to maintain perfectly the flight path in a 60° bank roll.
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Old 08-21-2019, 03:56 PM   #30
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after rewatching this videos, it seems quite flight path stable, the flight path vector barely moves

https://www.youtube.com/watch?v=NzRvZaz4sgw
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