J-20... The New Generation Fighter III

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Quickie

Quickie

Colonel
Engineer said:
Yes. Absolutely yes. If you want to explore the mathematical intricacy behind FBW system, I can also provide an introduction.


Projecting much?

I did not miss the points you've made. In fact, I pointed them out one-by-one and explained why your idea of FBW is not how FBW actually functions. I explained as carefully as possible why your assumptions don't work. Your ignoring of what I've said and insistence that your idea is the right one does not make me missed your point. Like I have said, I encourage you to go read upon this subject.


FBW can only work within the confine of data provided by the sensors. Hence, when the Inertial Measurement Units cannot distinguish between acceleration by air or ground, then the FBW does not know whether the aircraft is in takeoff mode or already in the air. Air data sensors cannot provide this information either, as different airport has different altitude and you cannot depend on air pressure (which is dynamic) to determine if the aircraft is taking off.


No. You keep on saying I claim FBW counteracts momentum, yet I have corrected you time and time again that FBW responds to acceleration, and that the FBW thinks it is responding to air disturbance when it rolls along uneven surface on the ground. At no time did I claim that the FBW is tasked to force the aircraft to be level if the aircraft reaches an incline, if that's what you are insinuating me to be saying. I specifically pointed out in my reply to delft that responses from the FBW while the aircraft is on the ground would be the same responses as if the aircraft is flying at stall speed. Perhaps you should make sure you grasp people's points before accusing others of missing yours.

And how can you expect me to not treat you as not knowledgeable in the subject if you can't even differentiate between momentum (kg m/s), acceleration (m/s2) and force (kg m/s2)?
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Those are basic stuffs. You're being childish to think that people here don't know this basic terms of mechanics. And no one is interested in the maths of FBW here and I'm sure you're not the only one here who can understand it. You seem to be going all over the place again outside the point I was trying to make.

Let me get direct to the point again and don't try to stray to the stuffs which I'm not interested.

Just answer this questions. My contention has always been that maintaining a level flight path parallel to the ground is not what a FBW system should be programmed to do during a takeoff.

Why on earth would you want the FBW to make the flight path as level as possible to the ground during takeoff? Wouldn't an upward movement of the aircraft due to whatever reason (which could be the runway's unseen mini ski jumps which are usually present in most runways) make the friction of the wheels lesser? Is it not that a counteracting force (which itself will increase drag due to a sudden change in air flow) to make the flight path back to the set-level again would actually increase the force on the wheels resulting in an increase of friction and increasing the drag on the aircraft? Wouldn't that be counterproductive? Again, just answer this questions and nothing else as I don't want to drag this discussion any longer.
 
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Engineer

Engineer

Major
Quickie said:
Those are basic stuffs. You're being childish to think that people here don't know this basic terms of mechanics.
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Apparently, they are so basic that you are using them interchangeably without distinction. How many times have I used the term "acceleration" and you come back and claim I said "momentum"?

Quickie said:
And no one is interested in the maths of FBW here and I'm sure you're not the only one here who can understand it. You seem to be going all over the place again outside the point I was trying to make.
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I'm sure plenty of people understand it, but I do not get the impression that you do. Do you or do you not understand it? If you don't and have no idea what you are talking about, then why are you wasting both our time?

Quickie said:
Let me get direct to the point again and don't try to stray to the stuffs which I'm not interested.

Just answer this questions. My contention has always been that maintaining a level flight path parallel to the ground is not what a FBW system should be programmed to do during a takeoff.

Why on earth would you want the FBW to make the flight path as level as possible to the ground during takeoff? Wouldn't an upward movement of the aircraft due to whatever reason (which could be the runway's unseen mini ski jumps which are usually present in most runways) make the friction of the wheels lesser? Is it not that a counteracting force (which itself will increase drag due to a sudden change in air flow) to make the flight path back to the set-level again would actually increase the force on the wheels resulting in an increase of friction and increasing the drag on the aircraft. Wouldn't that be counterproductive? Again, just answer this questions and nothing else as I don't want to drag this discussion any longer.
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Apparently, you do not read. Allow me to quote myself:
Engineer said:
No. You keep on saying I claim FBW counteracts momentum, yet I have corrected you time and time again that FBW responds to acceleration, and that the FBW thinks it is responding to air disturbance when it rolls along uneven surface on the ground. At no time did I claim that the FBW is tasked to force the aircraft to be level if the aircraft reaches an incline, if that's what you are insinuating me to be saying. I specifically pointed out in my reply to delft that responses from the FBW while the aircraft is on the ground would be the same responses as if the aircraft is flying at stall speed. Perhaps you should make sure you grasp people's points before accusing others of missing yours.
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I have always maintained that the FBW system responds to disturbances on the ground as it does in the air. The FBW thinks it is responding to air disturbance. You are not moving this discussion forward when you keep on insisting I made some statements that I have not made, and I freaking hate it when people do that.
 
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Quickie

Quickie

Colonel
Engineer said:
Apparently, they are so basic that you are using them interchangeably without distinction. How many times have I used the term "acceleration" and you come back and claim I said "momentum"?.
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Simple. Momentum relates closely to the energy (k.e.) and the force at play in the context of my points. Acceleration doesn't relate to anything in that context.

I'm sure plenty of people understand it, but I do not get the impression that you do. Do you or do you not understand it? If you don't and have no idea what you are talking about, then why are you wasting both our time?
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The problem is with your choice of wordings like the above? People don't like to hear things like that and they tend to reply in kind.

Apparently, you do not read. Allow me to quote myself:

I have always maintained that the FBW system responds to disturbances on the ground as it does in the air. The FBW thinks it is responding to air disturbance. You are not moving this discussion forward when you keep on insisting I made some statements that I have not made, and I freaking hate it when people do that.
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That's not how I've come to understand it. Looks like I'm not going to get the answer to my question. I the hell hate this discussion too. So this shoud be the end of it.
 
Engineer

Engineer

Major
Quickie said:
Simple. Momentum relates closely to the energy (k.e.) and the force at play in the context of my points. Acceleration doesn't relate to anything in that context.
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Right, the context of your points; in other words you are arguing with yourself and not responding to anything I have said. What I have said is that FBW responds to acceleration which is determined by the IMU, but IMU cannot tell the source of acceleration, leading to FBW responding to uneven ground. From now on, everytime you misquote me on using momentum, I am going to correct you with the above sentence.

Quickie said:
The problem is with your choice of wordings like the above? People don't like to hear things like that and they tend to reply in kind.
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So do you?

Quickie said:
That's not how I've come to understand it. Looks like I'm not going to get the answer to my question. I the hell hate this discussion too. So this shoud be the end of it.
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If you are expecting me to walk into some sort of false dichotomy trap, then I will have to disappoint you.
 
P

paintgun

Senior Member
i.e. said:
:p
this is neither the right place nor the audience.
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why not i.e? it would be good to have an authoritative source on this matter on sinodefence, like jeff and popeye on carriers stuff, it would be nice to have you straighten plain silly wrong arguments we unable to see

we've had quite a number of this endless discussion, either from both side unable to convince each other, or some just being dense

but i believe that there are many here that will be eager to learn from you, or anyone with competence, but its your call :)

sorry for OT
 
Quickie

Quickie

Colonel
Engineer said:
Right, the context of your points; in other words you are arguing with yourself and not responding to anything I have said. What I have said is that FBW responds to acceleration which is determined by the IMU, but IMU cannot tell the source of acceleration, leading to FBW responding to uneven ground. From now on, everytime you misquote me on using momentum, I am going to correct you with the above sentence.
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All the while, I've the impression we disagree on how the FBW will respond to the sensors input under different conditions. Lol, good thing is that i.e. said we're both wrong and that kind of shut the up the whole discussion since now there're now at least 3 people in disagreement on the subject.

So do you?
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Lol, who took the first snipe? But it's a small matter, so let's just forget it.


If you are expecting me to walk into some sort of false dichotomy trap, then I will have to disappoint you.
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It's nothing important actually and I think I'll just stop here before the "heavy breathing guy" comes breathing down my neck.
 
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I

i.e.

Senior Member
paintgun said:
why not i.e? it would be good to have an authoritative source on this matter on sinodefence, like jeff and popeye on carriers stuff, it would be nice to have you straighten plain silly wrong arguments we unable to see

we've had quite a number of this endless discussion, either from both side unable to convince each other, or some just being dense

but i believe that there are many here that will be eager to learn from you, or anyone with competence, but its your call :)

sorry for OT
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Do it on the internet is stupid.

Sometimes I have hard enough time convince people who are my colleagues,
I have to pull out alot of data and analysis to show them.
there are knowhows that alot of people who are in the industry 20 years may not even know about.

Plus most of this stuff is borderline ITAR



plus knowledge is not free. my rates are higher than the enjoyment I get from informing strangers on internet :)
 
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