I love the BMS flight model
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@Mav-jp said in I love the BMS flight model:
Gxcos(theta)
Exactly Gxcos(theta) is only on pitch axis. It doesnt change that much in a knife edge maneuver
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@Mav-jp said in I love the BMS flight model:
Guys please , you cannot apply standard flight mechanics theory on a FLCS aircraft, you need to study and understand the FLCS before drawing any analysis
Look, I am certain you know and understand the FLCS better than me and better than perhaps all of us.
I am not engaging in a fact fight.
I commented about the knife edge at first place because of personal experience I had in a recent event at Lockheeds martin very own full flight simulator.
In fact I tried a bunch of other maneuvers
It was exactly like the video. No heading change more than 4-5degrees without pushing the stick down.
Feel free to question if I am valid in what I am saying or not. I just pointed out something that I think might be not exactly accurately perfected in bms.
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@Mav-jp You have been most helpful in my other fm questions. Peace !
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@frapes45 said in I love the BMS flight model:
@Mav-jp said in I love the BMS flight model:
Gxcos(theta)
Exactly Gxcos(theta) is only on pitch axis. It doesnt change that much in a knife edge maneuver
Jeez the accelerometer measures on the Z axis
When you bank 90 deg it measures 0 from gravity
NZ = GxCos(theta)xcos(Phi)
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@Mav-jp cos (phi) ? Isnt Ļ the roll axis?
It would be very interesting if it actually accounts for roll angle.
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@frapes45 said in I love the BMS flight model:
@Mav-jp cos (phi) ? Isnt Ļ the roll axis?
It would be very interesting if it actually accounts for roll angle.
Okay please read nasa TP1538
https://www.cs.odu.edu/~mln/ltrs-pdfs/NASA-79-tp1538.pdfPage 2 , dƩfinition of An
And page 37 appendix B which gives you how this is computed
As you can see it takes both pitch and roll angles into account (with accelerations on all axis for dynamic )
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@Mav-jp not only that, An is also dependant on pitch acceleration among other things
Ļ is the euler angle for roll.
It is also not as simple as Z axis reading 0g as you mentioned initially.
Dont want to sound rude or insulting at all.
I will keep looking. Obviousely I am not in a position to know if and how the bms flcs is precision engineered.
Kind regards
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@frapes45 said in I love the BMS flight model:
@Mav-jp not only that, An is also dependant on pitch acceleration among other things
Ļ is the euler angle for roll.
It is also not as simple as Z axis reading 0g as you mentioned initially.
Dont want to sound rude or insulting at all.
I will keep looking. Obviousely I am not in a position to know if and how the bms flcs is precision engineered.
Kind regards
Thank you I think I know what the Euler angles are
BMS flight models includes An that is described in the nasa TP1538 , including all rates p,q and Wdot
My comments earlier was a simplified approach to make you understand the effect of pitch and bank on the flcs response which explains why the FLCS commands pitch up when banked at 90deg
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@frapes45 said in I love the BMS flight model:
@Mav-jp not only that, An is also dependant on pitch acceleration among other things
Ļ is the euler angle for roll.
It is also not as simple as Z axis reading 0g as you mentioned initially.
Dont want to sound rude or insulting at all.
I will keep looking. Obviousely I am not in a position to know if and how the bms flcs is precision engineered.
Kind regards
BMs flcs is not engineered, itās a copy paste of the real
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@Mav-jp me so sorry for starting this all
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@Mav-jp said in I love the BMS flight model:
BMS flight models includes An that is described in the nasa TP1538 , including all rates p,q and Wdot
My comments earlier was a simplified approach to make you understand the effect of pitch and bank on the flcs response which explains why the FLCS commands pitch up when banked at 90deg
Yes, I understand.
A lot of interest lies on pages 99-104 on the document showing how An varies accordingly to the euler angles in diagrams when various maneuvers are perfomed including 70 to 70 degree bank to bank. It would be nice if we could compare that data to the BMS flight model for FM evaluation.
At first glance there is no change on Īø even with An changing to positive number. That means the plane will not turn by the computer and it would not require to push down the stick
There is my proof that something is going wrong with bms when banking
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@frapes45 said in I love the BMS flight model:
@Mav-jp said in I love the BMS flight model:
BMS flight models includes An that is described in the nasa TP1538 , including all rates p,q and Wdot
My comments earlier was a simplified approach to make you understand the effect of pitch and bank on the flcs response which explains why the FLCS commands pitch up when banked at 90deg
Yes, I understand.
A lot of interest lies on pages 99-104 on the document showing how An varies accordingly to the euler angles in diagrams when various maneuvers are perfomed including 70 to 70 degree bank to bank. It would be nice if we could compare that data to the BMS flight model for FM evaluation.
At first glance there is no change on Īø even with An changing to positive number. That means the plane will not turn by the computer and it would not require to push down the stick
There is my proof that something is going wrong with bms when banking
You do realize that BMS IS the NASA model right ?
Nothing , absolutly nothing can compensate the An commanded feedback in the flcs
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By the way long time ago I flew with cos(phi) inhibited in the FLCS for testing purpose , itās very very weirdo
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@Mav-jp said in I love the BMS flight model:
By the way long time ago I flew with cos(phi) inhibited in the FLCS for testing purpose , itās very very weirdo
xD So its not inhibited as of now?
I thought bms follows the nasa modelā¦
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@Mav-jp said in I love the BMS flight model:
itās very very weirdo
And you are judging based on how many flight hours ?
Please look the pages I mentioned.
Look for the bank to bank diagram.
Īø angle remains the same no matter what bank angle you are at. ( 70 to 70 degrees)
I doubt thats the case on bms as of now.
BTW No hard feelingsā¦
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@frapes45 said in I love the BMS flight model:
@Mav-jp said in I love the BMS flight model:
itās very very weirdo
And you are judging based on how many flight hours ?
Please look the pages I mentioned.
Look for the bank to bank diagram.
Īø angle remains the same no matter what bank angle you are at.
I doubt thats the case on bms as of now.
BTW No hard feelingsā¦
As a matter of fact, maybe you should have a look of what phi theta and psi means , because it seems you are a bit confused on the matter (BTW no hard feelingsā¦)
In the NASA document the euler angles are the angle of the aircraft versus the fix referential of earth.
Phi is roll
theta is angle from horizontal
Psi is angle headingExample of description here:
https://en.wikipedia.org/wiki/Euler_angles#/media/File:Plane_with_ENU_embedded_axes.svg
So , in the manoeuver bank to bank, illustrated Figure 56
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theta stays stable as airracft is not really pitchin up or down compared to horizon
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what you need to look at is PSI angle which reveals the heading motions :
AS you can see, lets analyse first bank , the pilot is executing the first bank from +5 seconds to 15 seconds.
Phi angle is maximum at around 12.5 seconds and stays there until around 15 seconds
Pay attention that during this period FLongN is a bit positive which means the pilot still gives some input therefore the analysis will be biaised
During this time, the PSI angle (heading) has built up to 50 degrees deviation,
you can also see that the pitch rate (q) is also building up while rolling, which is due to both FLCS commanding pitch , pilot input AND inertia coupling
As a matter of fact, this test has been performed in order to test the Roll limiters systems (A , B, C ) and to measure their resistance on the inertia coupling during those manoeuvers
So , your āproofā is actually only a proof that you misinterpreted the meaning of theta angle.
as this test is performed with pilot stick input, we cannot demonstrate really anything on the matter.
the only thing we know is that the FLCS commands 1G pitch up all the time, and particularly when rolled at 90 deg, which provokes heading deviation
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When you look at the knife edge pass :
you can see in the HUD the G meter is readin close to 0
In order to achieve 0G in the F16 there is only ONE WAY : to push on the stick , the FLCS does NOT command 0G when banking, the FLCS of the F16 ALWAYS commands 1G with no pilot input, no matter what.
Thatās a basics of the F16 FLCS, now you are entirely free to not accept this fact, but there is nothing more i can tell you to explain.
Iām out
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the FLCS of the F16 ALWAYS commands 1G with no pilot input, no matter what.
This statement is very absolute and so not true. You said it yourself An commands the FLCS not the G force.
It seeks 1G it doesnt mean it always commands 1G.
The hud G reading is only indicative and its absolutele normal for it to show values near 0 when banking with such sharpness.
I am telling you its not the same on real viper simulator I have tried myself. Feel also free to believe what you want.
Also you falsely claim that Ļ is the true indicator of heading change when banked.
This is completely wrong. If that was the case we should see 50 degrees heading deviation when banking 70 degrees according to the chartā¦As of now it changes way to much heading when banking
Does GCAS also command 1g lol
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@Mav-jp said in I love the BMS flight model:
what you need to look at is PSI angle which reveals the heading motions :
I am sorry but that statement is totaly incorrect.
ĪØ angle when banked at 70 degrees doesnt show heading change at most. It mostly shows you are heading either towards the sky or the ground.
It seems you have difficulty understanding the dynamic of the euler angles. When banked 90 degrees Īø will show you if yĪæu change heading not Ļ
You also seem to base your theory on the hud feeding g sensor which is seperate and different in location than the one FLCS uses.
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@frapes45 said in I love the BMS flight model:
@Mav-jp said in I love the BMS flight model:
what you need to look at is PSI angle which reveals the heading motions :
I am sorry but that statement is totaly incorrect.
ĪØ angle when banked at 70 degrees doesnt show heading change at most. It mostly shows you are heading either towards the sky or the ground.
It seems you have difficulty understanding the dynamic of the euler angles. When banked 90 degrees Īø will show you if yĪæu change heading not Ļ
You also seem to base your theory on the hud feeding g sensor which is seperate and different in location than the one FLCS uses.
i feel ashame for you now , sorry.
have a good time