Why Red Flag exercises are not indicative of aircraft performance

Similar to mig-25 so I think that pretty high sweep

It's not. The sweep of other aircraft has nothing to do with it, it's the sweep relative to vortex generation. It's besides the point though, I brought up sweep because it helps vortex generation, and the F-14's gloves are highly swept. The F-15 doesn't have a comparable LEXR surface, only the fuselage fairings. They won't produce the same amount of lift.

They can increase lift at AOA similar to F-15 belly , but of course it won't be like F-16 LERX

In raw lift generation, they will be inferior to the F-14 as well.

Gloves vanes are deploy at supersonic for stability and F-14D don't have them anymore

The D still has the gloves themselves, and what I said applies to them. The air will go for the easiest path. The stubby F-15 fairings don't give the air much of a reason to go around the side and form a vortex. They will probably also generate unsteady separation earlier than the F-14 or F-16 because they won't have as sharp a pressure gradient.

I don't think we can really tell from pictures , there are too limited number of picture where F-15 , F-14 even produce even a small amount of vortex

I'm not looking at pictures, I'm looking at the shapes themselves. That alone will give you a good idea of what they do and how they perform. Not perfect, but enough to have a decently accurate ranking.

Which is quite hard because F-14 wing have different CL at different sweep angle

This shows up in the ITR as long as the aircraft isn't artificially limited, so it's accounted for.

Then high yoyo ?

If the other plane can't point its nose up, why not.

Most of the time it better than going too slow and have no energy

"Most of the time" doesn't matter to specific situations though. What is best most of the time isn't best all the time.

I think the problem is nose point ing or Max ITR required you to either success or face really bad consequences , in game it OK because if you die you can start over , in real life most pilot would play it safe

And what is safest again depends on the situation. Rocketing past someone just to take a missile in the back isn't safe.

I think this has gone off track. I wasn't trying to counter your argument. I stepped in because it seemed like there was a deadlock and I thought it was from each side meaning something other than what the other thought.

It's not. The sweep of other aircraft has nothing to do with it, it's the sweep relative to vortex generation. It's besides the point though, I brought up sweep because it helps vortex generation, and the F-14's gloves are highly swept. The F-15 doesn't have a comparable LEXR surface, only the fuselage fairings. They won't produce the same amount of lift.

Neither the curve surface of F-14 or F-15 are called LERX or can achieve what F-16 LERX can

If you count the curvry part then I have to say F-15 LERX have very high sweep too

In raw lift generation, they will be inferior to the F-14 as well.

I doubt that , F-15 out performe both F-14 and F-16 at high altitude

The D still has the gloves themselves, and what I said applies to them. The air will go for the easiest path. The stubby F-15 fairings don't give the air much of a reason to go around the side and form a vortex. They will probably also generate unsteady separation earlier than the F-14 or F-16 because they won't have as sharp a pressure gradient.

Iam sure F-14D don't have the golves vane anymore

http://www.anft.net/f-14/f14-detail-glovevane.htm

I'm not looking at pictures, I'm looking at the shapes themselves. That alone will give you a good idea of what they do and how they perform. Not perfect, but enough to have a decently accurate ranking.

Iam skeptical of that , shape can sometime deceiving

Mig-25 look like a brick yet it fly higher and faster than all fighter

su-27 look sleek yet it is slower than F-15

This shows up in the ITR as long as the aircraft isn't artificially limited, so it's accounted for.

But then F-16 is AoA limited

And what is safest again depends on the situation. Rocketing past someone just to take a missile in the back isn't safe.

We probably should left missiles out of comparison since with modern HOBS missiles a few degree superior in tun rate is rather irrelevant

Sorry garrya but I can't help but find it amusing that you think I'm confused when you can't tell the difference between a lift curve and an ps=0 curve.

 

Anyway I'm done with the semantics, let's put the facts on table:

 

The F-14's wings start to sweep back at around Mach 0.45, a fact to which you were completely oblivious garrya.

 

At a speed of Mach 0.85 and at any altitude below 14,000 ft the F-14's wings are already at 55 deg sweep (50.5 deg >20 kft), and by Mach 0.94 they are fully swept at all altitudes.

So F-14 can reach mach 2.4 bellow 14000 feet ?

.

Regardless of this however the lift curve remains higher than that of the F-16 & F-15, and that only because of its lifting body design.

As an example at 35 kft and at a speed of Mach 1.0 (the point where the F-14's wings are already fully swept) the F-14's max instantanous load factor is 5.7 G's, where'as by comparison F-16C's max instantanous load factor at the same altitude and speed (DI = 50) is 5.5 G's. In short the F-14 maintains an ITR advantage even when its wings are fully swept.

 

A superior ITR can only be achieved in one way, and that is with a superior lift to weight ratio, thus the conclusion of the above can only be one thing: that the F-14 has this advantage across the entire speed range.

At its corner speed F-16 with CFT can pull about 8-8.3G at 30k feet

Then again F-16 is AoA limited and as a small fighter it is affected more by weapon load than F-14 , F-15

*sigh*

I give up...

 

 

 

 

 

 

Where can be found these PE curves? I have a book about F-14A's PE curves with similar chart but this is with GE engine the later version. If it is payware I do not care I wish to buy. I'm very eager to see PE curces of F-14B/D.

Where can be found these PE curves? I have a book about F-14A's PE curves with similar chart but this is with GE engine the later version. If it is payware I do not care I wish to buy. I'm very eager to see PE curces of F-14B/D.

No need to buy anything, you can download here:

http://www.mediafire.com/file/3krzacmc49cq4fo/F-14A+BD+PERF.pdf

No need to buy anything, you can download here:

http://www.mediafire.com/file/3krzacmc49cq4fo/F-14A+BD+PERF.pdf

Big Thx!

garrya said:

...according to this chart F-15 sustain G limit at 10k feet is 8.5 G , so shouldn't it be much better than both the F-16C and F-14D ?

....

Hi,

You misinterpreted the diagram. Those curves are for maximum (instantaneous) turn rates according to speed/Mach and altitude, not constant turn rates. These curves represent the maximum turn rate at critical AoA for a given speed (speed which normally drops due to excess drag).

The following chart also includes the real max sustained turn rates of the F-15 which are far lower than the constant turn rates that our "wonderful DCS F-15" seems to prove in game:

Cheers;)!

...Wrong , negative stability increase lift because the tail now increase lift instead of counter it

Exactly "garrya"..., but just like him, there are tens of others who understood the laws of physics and especially the aerodynamics so wrong and ironically it also makes sense to them (although very wrong). If you can't fight them with numbers (correct charts and accurate data), you cannot fight them with the knowledge that they don't have right!

Hi,

 

You misinterpreted the diagram. Those curves are for maximum (instantaneous) turn rates according to speed/Mach and altitude, not constant turn rates. These curves represent the maximum turn rate at critical AoA for a given speed (speed which normally drops due to excess drag)!

It say quite clear right there what it is "sustain level turn", besides, the chart represents sustain G

Exactly "garrya"..., but just like him, there are tens of others who understood the laws of physics and especially the aerodynamics so wrong and ironically it also makes sense to them (although very wrong). If you can't fight them with numbers (correct charts and accurate data), you cannot fight them with the knowledge that they don't have right!

:megalol::megalol:

I suggest you two geniuses learn to interpret the charts first before you fling out statements like that.

On 4/3/2019 at 3:24 PM, Hummingbird said:

 

:megalol::megalol:

 

I suggest you two geniuses learn to interpret the charts first before you fling out statements like that.

":megalol::megalol:" here you have it "genius", this one's complete, not just with the sustained (indeed sustained, not instantaneous) max G-load/turn rate, but also the constants graph:

On 4/3/2019 at 7:53 AM, garrya said:

It say quite clear right there what it is "sustain level turn", besides, the chart represents sustain G

Yes, my mistake! After looking at charts like these for decades once in a while you get confused. Most that I saw were usually showing the best instantaneous rates while the IAS can't be held (decreases), but yes, the title wasn't wrong as I initially supposed and it resembles the constant G-load that settles at a constant IAS and AoA for a given MSL. To not flood this thread with the same pictures again, you can find it a bit above as the initial link is gone so I've uploaded it as a picture.

Cheers! o7

But speaking of witch..., I've just done a short test in DCS again (latest beta version) and "voilà"..., the F-15C at exactly 37000 (locked the fuel to unlimited in mission editor), the F-15C at sea level, at Mach ~0.5 and ~14.5 AoA has not 5.2..5.3 Gs as it should, but 5.9 which is a considerable difference to the real plane. Again and again, proofs show that most of our jet fighters in DCS require FM overhauls once in a while. For the sake of DCS's reputation, not for me...!

F-15 higher than normal turn rate performances (probably lift vs AoA related).trkF-15 higher than normal turn rate performances (probably higher than normal lift slope for given drag vs AoA).acmi