My F-15j with AAM-3s sat at 12.7… i do feel bad using it if not for the fact all i see in it are the god damn su 30 players dragging me up to 13.3… Let me have some god damn peace man.
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The 13.3 flankers are the worst thing since that dual auto cannon Russian thing
The EFT document has a comparison of STR , ITR, and SEP of a few different planes. Amongst those are Gripen and Rafale but it is unclear in the document what information the predictions are based on; i.e is a clean sheet analysis by UK aero engineers or if figures are based on information provided by the manufacturer etc.
The document shows Gripen with STR of approximately 65% of ESR-D requirement which is 20 degrees per second st sea level with full fuel and 2 IR missiles.
There is AIAA article with Gripen STR chart as well that only specified that it’s at low altitude and makes a comparison to Viggen. One can interpolate values by cross referencing the Viggen line in that chart. When checked against the R,KM or sea level chart the Gripen STR line is basically 1 - 3 degrees over it. Moreso at higher speeds / near transonic which is something that is not unique to the Gripen.
The UK document is plausible if you consider the AIAA chart to be at 50% fuel and clean vs Gripen w/ full fuel. Typically WarThunder aircraft do not have the same margin of performance decline for increased weight as their real life counterparts.
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VIFF Explanation / added capabilities (To the bets of my abilities)
Seeing as VIFF is an extremely complicated topic, and since I’ve not been able to “convince” a generally accepted “additional capability provided by the use of CTVC (Combat Thrust vector control)” I’ll explain my rationalizations in full. The idea of this write up is for the “community” to have a better understanding of how CTVC works and the performance actually achieved via its use. I will include the source material and where to view it for yourself if you are so interested.
Conventional aerodynamic thinking and principles can often times not be applied to an aircraft such as the Harrier. For this reason its understandable that most people would be skeptical of its claimed performance benefits, even despite my primary source material.
Explaining additional G capability:
Additional G obtained by the use of CTVC is caused by the combination of several key aspects.
1- The action of imparting some of the GROSS thrust of the engine naturally results in the addition of jet lift. Net thrust can no longer be used in calculations regarding the use of CTVC as intake drag only operates inline with the intakes face
A good % of the total gross thrust is actually lost due to jet interference effects at higher nozzle angles. However the added G even when the nozzles are lowered past the optimum angle of 60 degrees is still .5-.75 on the Harrier. When at 60 degrees nozzle angle or less the gross thrust in combination with everything explained below results in a much greater achievable G.
2- The Jet interference effects caused by the change in velocity and relative pressures in the ambient airflow across the entire wing. As the nozzles are rotated, the local airflow around the wind starts to trail downwards resulting in the wing experiencing a local AOA drop. However the Coefficient of lift actually increases. The increase in lift coefficient and the gross thrust imparted downwards allows for more G at any given AOA despite the wing actually producing less lift at the given AOA due to its relative AOA being lowered by the thrust interference effect.
It is extremely difficult to quantify exact incremental G addition at any given speed and AOA as the Coefficient of lift, Gross thrust / gross thrust % loss due to jet interference effects, Local wing AOA vs aircraft datum AOA, and Engine RPM / gross and net power output are always and constantly changing.
However it has been observed, measured, and accepted that an additional 1-1.5G can be achieved when using TVC (optimum nozzle angle of 60 degrees) to aid in a maximum instantaneous turn when the engine is operating in the 95.5% RPM band. With higher engine ratings almost definitely allowing more.
Visualization of the added coefficient of lift resultant from the use of TVC
Above 60 degrees of nozzle angle the jet induced airflow will begin to separate from the wing and cause the airflow to stall and swirl resulting in massive amounts of drag being created even when flying straight and level. This also drops the Coefficient of lift resulting in less G achieved.
No more than 60 degrees of nozzle angle should be used when the maximum instantaneous turn capability is desired.
The loss of speed resulting from the correct use of CTVC is not as great as one would expect.
Performing a 90 degree turn at 530 knots will end at 430 knots after 90 degrees using the 60 degrees of nozzle angle.
The use of lower nozzle angles can actually decrease the bleed rate of the Harrier.
High AOA and nose authority enhancements:
Furthermore CTVC, in addition to providing more available G, actually allows the harrier to maneuver at significantly higher angles of attack then the conventional stall angle of attack. The increased velocity around the entire wing increases the effectiveness of the ailerons and flaps allowing for precise roll control and improved stability.
The increase in ambient velocity and therefore pressure around the entire wing results in a boundary layer control (BLC) effect. This forces the airflow to remain attached to the wing well beyond what can be achieved with conventional aerodynamic principles.
For example The F-18A will achieve its maximum lift coefficient at about 32 degrees AOA to achieve this the wing is in very heavy buffet and the LERX is providing vortex lift to maintain the high lift coefficient. Above this angle of attack the curve begins to fall indicating stall.
The Harrier 1 - AV-8A for reference achieves its highest coefficient of lift at about 17 degrees AOA when flying like a conventional jet. However with the nozzles directed downwards the Harriers lift curve will continue to rise until 40 degrees AOA and the wing will have almost no buffet and or wing rock when doing so.
Tactical implications:
As I have stated many many times by now the Nozzles not only allow for a greater Instantaneous G to be achieved but it also provides a noticeable increase in low to medium speed sustained turn rates.
Above about .55 Mach the sustained turn rate decreases with the use of CTVC.
This provides a good visualization of the effects of CTVC on the performance envelope of the harrier.
Here you can see a comparison to a conventional fighter with considerably lower wing loading
IE a harrier vs MiG-21
Recall my previous statements about the two:
The use of CTVC allows the harrier to achieve significantly higher low and medium speed ITRs however as the speed rises and the nozzles no longer have the torque to achieve the rotational power needed to achieve the selected nozzle angle the MiG-21 is able to achieve slightly more ITR at its G limit vs the Harrier.
The second important aspect in CTVC is the use of large nozzle angles to generate extreme deceleration.
This is to achieve 2 combat advantages, a massive advantage in a 1 circle capability post high speed merge. Or to generate a large angle off and deceleration to foil a very close in threat aircraft.
No aircraft in the world is able to match the 1 circle performance of the Harrier. However at the same time, if you misuse the 1 deceleration aspect of CTVC you can find yourself too low on energy to effectively fight back. It is best used sparingly.
I think this summarizes to the best of my abilities what CTVC does and why I talk about it the way that I do. Contrary to what some may think I absolutely do not pull data and numbers out of thin air, I also do not mis match sources. I just tried to avoid having to explain this in full and just use the figures of added performance to try and compare tactical situations. Unfortunately people cant accept the validity of this data, maybe it seems impossible to them? Nevertheless this is a full explanation of CTVC and rationalization of the performance enhancements that I make claim too.
Sources:
Validation of AV-8B V/STOL Characteristics by Full Scale Static and Wind Tunnel Tests (AIAA)
https://arc.aiaa.org/doi/10.2514/6.1977-597
Aerodynamics of V/STOL aircraft -Performance Assessment- (Page 314)
The British Aerospace Harrier - case study in aircraft design
https://arc.aiaa.org/doi/book/10.2514/4.868634
AV-8A/C NATOPS manual
this is the 1983 addition I do not think it is available online, ask if you require additional information and references.
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And how many degrees per second is the Harrier turning for that first 90 degrees of turn? What’s the answer on this? Is it 19?
Maximum performance turn meaning to the limiting G
So 8G at 530 knots by the time you get to 90 degrees of turn you’ve bleed down to 430
16.3 d/s at 530 for 8G as the speed decreases the turn rate will increase at the given G.
At .6 Mach it’s stated to be 19 a seconds so at 430 knots 20 could be likely possible.
That’s a bleed rate around 18 knots per second if it takes 5.5 seconds to complete the turn.
So what is the average turn rate then? What is a fair value?
Edited it to include that
ZSU-57?
No bpmt or whatever
This is a perfect example of a claim that you are making by attempting to string multiple sources together to arrive at a conclusion that you want to believe. Let me explain why this conclusion is completely irrational.
First off let’s note something about one of your sources and the nature of vectored thrust.
Angling the thrust downwards will reduce the total amount of thrust that is applied in relation to the flight path. This is a basic trigonometric relationship; as thrust vector angle is increased the component of thrust that is propelling the plane forward is reduced.
At 60 degrees angled downwards the horizontal component of thrust will be equal to half of the total thrust. Lets keep that in mind.
Let’s use 28,000lb thrust as our reference number. No it is not our wet lift thrust but also these are most likely uninstalled values so for the sake of simplicity we will say that both will cancel each other out. However we cannot use the 15,500 lb as the reference weight because the chart that you prefer to brag about is the one at 17,211lb reference weight.
We can see the weight listed at the top.
28,000lb thrust x 0.50 (the horizontal component of thrust at 60 vector angle) = 14,000lb Thrust.
In this configuration our Harrier has a thrust to weight ratio 0.81.
The wing area of the Harrier is 201sq feet or 18.7 meters.
The wing loading at this weight is 85lbs / square foot.
In this configuration we have a plane with a thrust loading of 0.81lbs and a wing loading of 85lbs per square foot. And the definitive conclusion that you have arrived at is that in an 8G turn that it will bleed 18 knots per second.
Now let’s ask ourselves a very simple question…how does this 18kts per second figure that we have somehow arrived at compare to other aircraft when using a similar performance metric?
The 1996 GAO Report has an indication of what the bleed rate in terms of knots per second is for the F/A-18C and F/A-18E. It should be noted that the bleed rate difference at altitude is only different by 10 knots per second and that the F-18 is also G-limited in the same way that the Harrier happens to be in this case; i.e these figures are not for greater than an 8G turn.
The numbers that we care about here are 54 knots per second and 62 knots per second. Technically we could also throw in the F/A-18E’s as well for the sake of comparison.
So how does the F/A-18C compare to the Harrier in terms of thrust loading and wing loading?
This is from the GAO report but shows uninstalled thrust. However later in the report there are figures for installed thrust.
This table here lists the installed thrust of the F404-GE-402 to be 19342lb at 0.8 Mach. We will use this figure for our calculations since we used 0.75 mach figure to approximate the Harrier.
The weight of the F/A-18C in this document is approximately 32,500lbs. Our total thrust is 2 * 19,342lb which equals 38,684lbs. This gives us a thrust to weight ratio of 1.20.
The wing area of the F/A-18C is 400 square feet. This gives us a wing loading of 81.25lbs per square foot of wing.
In this case the F/A-18 has the advantage in both wing loading and thrust loading.
It has 1.48 times the thrust loading and 0.95 times the wing loading. The F-18 also has a higher lift coefficient + aspect ratio etc that causes it to produces more lift for a given angle of attack and wing loading.
So lets do a little math. Your claim is that the Harrier has a bleed rate of 19kts per second and the GAO claims that the best performing F/A-18 has a bleed rate of 54kts to 62kts per second. Your conclusion so far is that the Harrier I has a bleed rate that is effectively 1/3rd that of the F/A-18C while being disadvantaged in all aerodynamic aspects.
Now we can make the argument that GAO report is wrong about the F/A-18 bleed rate or that they averaged it at the wrong places. However keep in mind the bleed rate only changed by 10 knots from 15,000 feet to sea level.
The F/A-18 is not the only plane that has a bleed rate in averaged knots per second either. We can also compare it to a chart that you should be familiar with by now from the Korean F-16C Basic Employment Manual.
In this case the F-16C is at 50% fuel and perfectly clean. Wing loading and thrust loading are going to favor the F-16 in this case as well. There is no point in breaking down the numbers bit by bit because the relationship is going to be similar but even more one sided.
Nominally speaking our bleed rate for an 8G turn at around 400 KCAS down to 375 KCAS is an average between -22 and -34 knots per second bleed which is 28 knots per second. This is going to be at a lower angle of attack and done with a wing that has a much higher CL. Even if we apply the same relationship as the F/A-18 experiences and use a correction factor of 1.14…that reduces our bleed rate to 24 knots per second.
So here is what you would have us believe if we take your claims at face value.
A Harrier with higher wing loading and higher thrust loading will have roughly 1/3rd the bleed rate of the very best F/A-18 variant and it will also have 25% less bleed rate than an F-16 in an even more favorable comparison. In fact the Harrier I will experience phenomenally less bleed rate than the Harrier II with improved wing and maximum aft thrust.
Anyone with half a brain can see that these claims are complete bullocks and are due to you misinterpreting your own sources and not using an ounce of critical thinking or any kind of comparative analysis.
This video here is bookmarked to start at the question that asks specifically about the usage of VIFF in the Harrier. Note that it is described as having the drawback of massive amounts of energy bleed in a plane that is noted for its already high amount of energy bleed.
Basically you have done a whole entire song and dance to argue that the VIFF-ing in the Harrier is magical solution that effectively boosts the lift coefficient so far beyond its normal lift coefficient that a 50% loss in horizontal thrust only will make a plane that is drastically more energy efficient than planes specifically designed around energy efficiency.
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This is hilarious as you couldn’t figure out 1 simple thing.
You compared it to the bleed rate of a F-18 when the F-18 is pulling too its corner velocity.
The harrier in this example was just using a VIFF push turn to perform 90 degrees of turn at high speed.
One is giving its maximum AOA to achieve its G limit at the lowest possible speed. The other is gently pulling until it reaches its G limit at a very high speed.
So why did you compare corner velocity to 8 G at a high IAS? Maybe you think it makes you look smart?
Regardless your little song and dance here just proved you lacked the basic comprehension to understand the circumstances of this 1 situation.
For example the F-16A would bleed no speed when pulling 8G at 530 knots (.8) Mach
as it can sustain that
The F-18 likely would also bleed 0 speed
So saying it will bleed 25% less then the F-16 was rather funny to read
J P explains it very well here they had so many different techniques for VIFF including nozzle biting to assist in the STR.
Progressively biting in with 20-40 degrees of nozzle angle would take big bites out of the turn with little loss in airspeed.
All VIFF will result in a loss of speed, however as long as it is used properly the loss in airspeed is not as great as one would think.
Watch at 9 minutes and beyond
To conclude it for you, if YOU did any amount of thinking into this, you would come to realize that since VIFF adds considerable G to any given AOA then much less AOA needs to be used to achieve any given G.
So although thrust is being exchanged to achieve this you are likely going to bleed far less then you would via pulling normally as you are exposing considerably less reference area resulting in less lift induced drag.
This is not hard to follow, you can understand this. Stop being argumentative for the sake of arguing.
Nowhere in your comparison have you stated an altitude where this 18 knots per second bleed rate would occur. The starting speed that you have used for the Harrier is 530 knots to 430 knots. This is also why the bleed rate of the F/A-18 is also included as we can get a sense of how much altitude affects this performance metric in terms of knots per second.
If your argument is that I am skewing the results by comparing an 8G turn…realize that it is skewing them in your favor. If we compare a harder turn for the F-16 then the bleed rate will just further increase. Picking the turn that I did was more favorable to your case.
It’s not a perfect comparison but the difference is so many orders of magnitude greater that its valid. The only other thing to do would be to get the actual EM diagram and compare SEP values at sea level. But even your sources are pretty clear about the utility of VIFF.
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It’s not you’re grasping at straws and you know this.
F-16 can sustain 9G for this scenario.
Naturally the data is for sea level.
It states very clearly that VIFF allows the harrier to combat aircraft almost half its wing loading. It’s not the be all end all but it greatly increases the aircraft’s capability
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“Hold it’s own” against planes from a similar era which will all have drastically higher bleed rates than modern aircraft like the F/A-18C and E.
The hawker hunter will bleed much less then either of those 2. The hunter comes from a decade were maneuverability speed and climb rate where the most important aspect of the aircraft.
The Hunter has been called the spitfire of the jet age.
Be real now
Good luck finding a real one