Again a rookie mistake. Drag has ZERO effect on velocity. I think you meant Lift? Drag has no effect on Lift either!! It is Lift that induces the Drag. Hence the term 'induced drag'. Induced from what? From lift. Velocity is a velocity whereas Lift and Drag are essentially accelerations! I'm sure you can appreciate a high ranking university's neutral stance on not endorsing any companies and their products? I'm sorry if I wasn't familiar with the PDF lingo.
And dubious qualification. lol. 2010-2014 B.Eng in Aeronautical Engineering from Loughborough University and 2014-2016 M.Phil in Advanced Materials Science (With Aerospace Materials) from University of Leicester. Many PDF members (including former Administrator Asim) know me from facebook and can varify this. Sir If I was to send you my certificates, transcripts and my dissertation, will you be able to promote me to a 'Professional' or 'PDF Think Tank: Analyst' or something? You may go and check my induction thread. I've been a member since I was just doing my Bachelors.
All in all, I dunno if you've misunderstood me or just dismissed my opinion as a nobody (I don't blame you) of the forum before knowing my credentials. But I have never disputed Rafale and Typhoon are superior to MKI. I just said TVC is certainly a useful feature to have and MAYBE just MAYBE Su-30 MKI has an edge in dogfights.
I never disputed that dogfights are becoming less and less common these days and so on. All of that is well established. Anywyas, I'm off to sleep it's half 3 in the morning here. We shall continue this tomorrow.
Again, qualifications or otherwise matter little in an anonymous forum. You can be the queen of England for all I care, it is your logic based on the laws of aerodynamics and not whether your university shunned all mention of the F-16 like voldemort that matters here. What Asim knew or not knew is also irrelevant since beyond a dinner I know nothing of Asim nor he of me. I dont dispute your qualification nor endorse it because it is irrelevant on an anonymous forum.
Im not sure what rookie mistake is when you claim that drag has no effect on velocity(
although the actual term would be speed since velocity is a relative term depending upon how you look at it) . So even if the increased velocity results in a higher drag, that drag is to have no effect on the aircraft?
If I remember these guys(and supposedly they are good)..
According to what it says there and to this rookie since I really know little about aerodynamics and aircraft beyond obsessing over it; drag does not like thrust. Which unless exceeds drag means the aircraft is going to slow down. Now nowhere am I implying that drag makes velocity and not the other way around, but if one takes drag as higher to thrust.. then a higher drag will lead to a reduction or negative acceleration. Which means that it is no longer displacing within the airspace at the same rate as it was before. So if by some reason the combination of both induced and parasitic drag exceeds the available thrust of the aircraft.. I would reckon that by basic addition of forces that are generally ok for even high school kids..the velocity of the aircraft would be lost.
So regardless of the qualifications, your own post has the answer to the question how drag will effect lift even though it is the other way around. If we go by the basic stuff NASA has put out there and your talk of induced drag (
which being dependant of the characteristics of the wing and the angle of attack in a nutshell..unless you want to quote Kermode's "mechanics of flight" which you are welcome to) which has a variable of angle of attack in it.
Within this mindboggling ideas of lift, drag , thrust and weight are rates of turn which come about due to an aircraft's bank angle and then centripetal force and all those wonderful and plentiful set of equations that are best suited for those with formal study to claim sole rights of understanding and ownership apparently.
BUT, going on this line.. that critical angle of attack where the maximum lift occurs and beyond that is what we call a stall. Sure that comes about a wonderful and variable graph of Lift coeff and AoA , not to mention speed.. but at the end.. it is a loss of lift(
unless you have a better definition for it). Now you can post away various equations and definitions but at the end there is no denying that an aircraft is able to maintain control in the air via directing the airflow around it. So if it loses that airflow due to a decrease in speed or disruption of airflow or whatever various tangential terms you wish to choose.. the bottom line is that the aircraft will lose its effectiveness in controlling its direction.Now here is a funny thing. Because you are trying to create more lift(or maintaining it in case of turns)by increasing your AoA) you are creating induced drag..drag that needs thrust to balance it.. otherwise you will reduce the airflow over the wings and lead to a reduction in the rate of displacement in air(
rather simplistic way to say it but) and velocity.
Which brings us to Post-stall manoeuvring or for the audience.. being able to point the aircraft where you want to after losing your ability to do so with your aerodynamic surfaces. That is where TVC came into play. The idea that if you got into a situation where you exceeded your aircraft's aerodynamic capabilities and now were looking to still be able to point your nose where you needed it was the basic drive for this technology's rise. This could mean pointing your nose when you would normally would not be able to or pointing it faster than your aircraft's aerodynamic forces would allow you to.
That created a lot of excitement during the early 80's since back then the best Air to Air missiles still needed you to have their seeker pointed at the enemy to make them lock on and go off like a hound dog. Additional benefits of TVC included a reduction in drag via aerodynamic surface deflection at high speed along with STOL capability(
you can explain away these things if you wish, you got the degree). Yet, at the end.. when using TVC for heavy manoeuvring.. you were still stalling the aircraft.. and basic physics meant that unless your aircraft had a ridiculous T/W ratio.. you will be falling out of the sky when you use that capability.
The USAF Flight dynamics laboratory had the following conclusion regarding post stall manoeuvring and turn rate:
"PSM is a result of high angles of attack, greater than the stall value. Two different problems were addressed. The first examined instantaneous turning performance. The second focused on minimum time turn problems. The impact of both vectored and nonvectored thrust was considered.
It was proven that minimum time turns fall in the vertical plane.
For maximum instantaneous turning rate and nonvectored thrust high angle of attack results if the speed is less than the critical speed which is approximately Mach 0.2. The optimal angle of attack approaches ninety degrees as the speed approaches zero. For vectored thrust, the stall angle of attack is optimum and the thrust vector angle is the complement of the angle of attack. PSM is not optimal if thrust vectoring is available.
For minimum time turning performance, maximum thrust is optimal. At the end of the trajectory, the optimal angle of attack equals that for maximum instantaneous performance. PSM is optimal. As the thrust to weight ratio increases, the maximum angle of attack increases."
Basically, TVC does not prove that beneficent to turning the tightest and instead is useful for pointing the nose the fastest.
Now considering that modern combat is built upon the foundations laid by that wonderful man known as John Boyd and his concept of energy fighting(
I dont think he made it up by the seat of his pants) which even the IAF uses as much as its avid fans like to not paint it out so. Here is a copy of it(
http://www.archives.gov/declassification/iscap/pdf/2011-052-doc1.pdf). In a nutshell, Air Combat is a science and not an art based on ever new ways of managing the "energy" of an aircraft (
potential to kinetic and vice versa in a simplistic way) and using it for setting up manoeuvres using those aerodynamic forces. Basically, what the man stressed is that an aircraft with low energy potential is a dead duck in combat. Pointing the nose in important, but effective energy management can negate that. Thus the idea of a energy fighter was born in the F-16 and even today aircraft like the MKI.
So when you have a system such as TVC that is essentially detrimental to energy conservation and optimal usage.. why would someone employ that except only as a last ditch manoeuvre. Perhaps against a single adversary without TVC the capability of pointing your nose faster is useful.. but when coupled with many vs many fights.. the idea of losing energy to kill one fighter whilst potentially creating a fatal situation for oneself seems rather a needless "extra". With today's high off boresight systems, that need to point the nose is also going away fast; so the main reason for TVC is gone.
But that is not the end of the story. Because there are three operational concepts seen of TVC. The first is the basic one dimensional thrust vector of the F-22.. only moves in the Y axis.(
if you look at it from the aircraft's nose) which is simpler in what it can do but also lowers costs..the 3D nozzle like that on the Mig-29OVT( move in both X and Y) but complex and heavy.. and the one in the MKI which moves in a gradient on X and Y and is essentially an attempt to get a compromise on generating both X and Y forces(which is a rather clever idea).
How that actually increases the drag verses a single axis movement like the F-22 or F-15 SMTD I will explain later.
And oh yeah.. did I mention the increase in weight which needs the installation of canards to counterbalance the aircraft? Although as such it brings benefits in fuel burn, takeoff roll and ability to keep RCS spikes from control surface movement low(although the idea of keeping the RCS low of an elephant like the MKI is laughable).
