Su-27 vs F-15C

[metzger]

Is it possible then to stay stelthy against AI?

I tried couple of times to hide in the mountains but It didn't work. He was all over me everytime.

 

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[*Rage*]

The AI has 100% situational awareness of enemy location and missiles launches regardless of range or line of sight.

[Stuge]

The AI has 100% situational awareness of enemy location and missiles launches regardless of range or line of sight.

 

Are you sure this is still the case? I've managed to score "stealth" ET kills against AI head-on, they wouldn't flare if the shot was from far enough distance(so that the missile has stopped smoking when it was closer to the target).

[Frostie]

Yes I think they have visibility limits now.

[metzger]

Yes I think they have visibility limits now.

How about from behind, does it matter?

Or things like radar on/off or ECM are calculated in the AI sa?

 

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[apocom]

..., since Eagle is a better gun platform currently. ...

 

Why?

[Stuge]

Why?

 

Eagle is more responsive (reacts faster to control input) and has less rotational inertia also. Aiming with Eagle is quick and intuitive, while aiming with Flanker is clumsier and needs more practice to damp out unwanted movements.

 

When you spend hours and hours shooting highly evasive targets you will understand the difference ;)

[DarkFire]

Eagle is more responsive (reacts faster to control input) and has less rotational inertia also. Aiming with Eagle is quick and intuitive, while aiming with Flanker is clumsier and needs more practice to damp out unwanted movements.

 

When you spend hours and hours shooting highly evasive targets you will understand the difference ;)

 

This. While I'd consider the actual gun on the Su-27 to be more accurate, and out to a slightly longer range, it's relatively easy to get in to a situation where you end up fighting the controls (low IAS, high AOA) not the enemy. If you're not used to how the aircraft behaves under those conditions it usually means death, particularly against a highly skilled BFM opponent.

 

As has always been the case, the F-15 offers more care-free handling and as noted has significantly lower roll inertia.

 

As an aside, I still think the yaw - roll coupling on the Flanker is much too strong, especially at low AOA and above ~250 Km/h, but that's a different discussion...

[Stuge]

While I'd consider the actual gun on the Su-27 to be more accurate, and out to a slightly longer range...

 

You're right Darkfire.

 

Flanker gun is extremely accurate all the way until 1,5 km range (where the pipper disappears), even at very high speed tailchases (600-700 kts indicated). It would be accurate even further away if the gunsight would support this. All you need is for the target to fly in a stable manner for enough seconds so you can take precise aim, fire, and let the bullets catch.

 

Meanwhile, Eagle's 20mm rounds both have a wider spread to begin with and in high speed tailchases lose speed so much that they never reach a target beyond a particular range, last I tested it was ~0,75 km which means its effective range in this case is only half of the Flanker's.

 

One interesting consequence of the Eagle cannon's large spread and extreme rate of fire, combined with the rapidly decreasing speed of rounds, is that in a head-on confrontation you can open fire early with a ~2 second burst to create a very thick shotgun shot -like "cloud" of bullets for the target to fly through. Unless the oncoming target evades, he will fly through the cloud and is likely to get hit. This technique is aided by the Eagle's gunsight not being range limited.

Edited September 4, 2016 by Stuge

[apocom]

Eagle is more responsive (reacts faster to control input) and has less rotational inertia also. Aiming with Eagle is quick and intuitive, while aiming with Flanker is clumsier and needs more practice to damp out unwanted movements.

 

 

Interesting, thx for the responce. I've noticed that I have an easier time to kill with guns in the eagle, but I thought it might be the pipper. The flankers one feels jumpier.

 

 

You must spread some Reputation around before giving it to Stuge again.

[Stuge]

Interesting, thx for the responce. I've noticed that I have an easier time to kill with guns in the eagle, but I thought it might be the pipper. The flankers one feels jumpier.

 

:):):) You're welcome :):):)

 

Naw, the Flanker pipper is good, it is pinpoint accurate. Eagle pipper on the other hand, last I checked, leads too little at longer ranges. Perhaps the effect of air resistance on the 20mm round is underestimated in the calculations, however I've heard they changed it recently so I don't know what the situation is currently.

 

Pipper jumpiness depends on target jumpiness and internet connection quality :) And the pipper logic is the same in both Eagle and Flanker.

[ShuRugal]

since Eagle is a better gun platform currently.

 

I wouldn't say it's a better gun platform, just that it has a lower skill floor. The Eagle is more forgiving of bad flying, so it makes it easier to safely whip the nose around for that snap-shot, without regards to actually flying the plane, but if the Flanker is flown within parameters, it still has better pointability. Just a matter of not pushing the envelope wrong.

 

 

In the hands of two pilots who both have good experience in type, and are both at optimal fuel weight, the Flanker should win a guns engagement more often than not.

[Stuge]

I wouldn't say it's a better gun platform, just that it has a lower skill floor. The Eagle is more forgiving of bad flying, so it makes it easier to safely whip the nose around for that snap-shot, without regards to actually flying the plane, but if the Flanker is flown within parameters, it still has better pointability. Just a matter of not pushing the envelope wrong.

 

This is not what I mean. I am talking about response time - the time between control input and the maneuver that results.

 

To prove my point I just did a quick test on positive pitch response time for both aircraft.

 

Straight and level, sea level (low altitude), 700 km/h (380 kts). Both aircraft very lightweight with no stores. Flanker's direct control mode was not used in this test.

 

Decelerated time to 1/32 and measured with a stopwatch the time in seconds from pulling the stick all the way back until the moment the aircraft hits angle of attack of 20, while hitting approximately 9 G. This would indicate when the aircraft has reached maximum performance turn from straight and level flight.

 

Results:

 

The Eagle took about 25 seconds while the Flanker took a whopping 80 seconds!!!

 

In real time this can be converted to less than 1 second for Eagle while it is almost 3 seconds for the Flanker!!! No amount of pilot skill can make up for such a big difference in response time, period. The fast response time is a huge benefit when gunning for extremely evasive targets that hopefully for their sake change their maneuvering direction every 1 second or less in unpredictable ways.

 

Response time in roll is also slower in Flanker, but I'll leave the extent of it for someone else to test ;)

Edited September 5, 2016 by Stuge

[apocom]

This is not what I mean. I am talking about response time - the time between control input and the maneuver that results.

 

To prove my point I just did a quick test on positive pitch response time for both aircraft.

 

Straight and level, sea level (low altitude), 700 km/h (380 kts). Both aircraft very lightweight with no stores. Flanker's direct control mode was not used in this test.

 

Decelerated time to 1/32 and measured with a stopwatch the time in seconds from pulling the stick all the way back until the moment the aircraft hits angle of attack of 20, while hitting approximately 9 G. This would indicate when the aircraft has reached maximum performance turn from straight and level flight.

 

Results:

 

The Eagle took about 25 seconds while the Flanker took a whopping 80 seconds!!!

 

In real time this can be converted to less than 1 second for Eagle while it is almost 3 seconds for the Flanker!!! No amount of pilot skill can make up for such a big difference in response time, period. The fast response time is a huge benefit when gunning for extremely evasive targets that hopefully for their sake change their maneuvering direction every 1 second or less in unpredictable ways.

 

Response time in roll is also slower in Flanker, but I'll leave the extent of it for someone else to test ;)

 

Wouldn't it be more interesting to do the same test with direct control enabled?

[Stuge]

Wouldn't it be more interesting to do the same test with direct control enabled?

 

Well since you asked I tested it quickly from 600 km/h (any faster breaks the wings). With direct control the Flanker seems to pretty much match the Eagle's response time in pitch.

 

However, considering the subject matter (shooting highly evasive, high speed targets) direct control is out of question since using it at high speeds such as 600+ kts (1100+ km/h) is extremely unstable and will result in suicide unless you have replaced your regular brain with custom built fly by wire computer for the purpose :)

[apocom]

Sorry to ask you that, but I don't know to test it myself. How are the relaxed controls (W) performing?

[Stuge]

Sorry to ask you that, but I don't know to test it myself. How are the relaxed controls (W) performing?

 

For me it's useless now. At slow speed direct control is better while at high speed using W will result in broken wings..

[DarkFire]

This is not what I mean. I am talking about response time - the time between control input and the maneuver that results.

 

To prove my point I just did a quick test on positive pitch response time for both aircraft.

 

Straight and level, sea level (low altitude), 700 km/h (380 kts). Both aircraft very lightweight with no stores. Flanker's direct control mode was not used in this test.

 

Decelerated time to 1/32 and measured with a stopwatch the time in seconds from pulling the stick all the way back until the moment the aircraft hits angle of attack of 20, while hitting approximately 9 G. This would indicate when the aircraft has reached maximum performance turn from straight and level flight.

 

Results:

 

The Eagle took about 25 seconds while the Flanker took a whopping 80 seconds!!!

 

In real time this can be converted to less than 1 second for Eagle while it is almost 3 seconds for the Flanker!!! No amount of pilot skill can make up for such a big difference in response time, period. The fast response time is a huge benefit when gunning for extremely evasive targets that hopefully for their sake change their maneuvering direction every 1 second or less in unpredictable ways.

 

Response time in roll is also slower in Flaner, but I'll leave the extent of it for someone else to test ;)

 

 

It strikes me that the best tactic against a target that's ducking and diving constantly is to... Let them do it, and observe from a safe distance. They waste energy while you don't. Easier said than done obviously, but still...

 

As for roll response, the chart in the manual says that the Flanker tops out at nearly exactly 180 degrees / second, co-incidentally at around 750 Km/h, which is also of course very close to corner speed. Can't imagine that this is a co-incidence and was probably a conscious design decision.

 

I know comparatively little about the Eagle but isn't it artificially limited to some insane value like 340 degrees / second?

[Stuge]

It strikes me that the best tactic against a target that's ducking and diving constantly is to... Let them do it, and observe from a safe distance. They waste energy while you don't. Easier said than done obviously, but still...

 

Yes, this is smart as long as the target does waste the energy... when he's slow he will be easier to shoot.

 

However, an Eagle can keep up speeds of 600+ kts while dodging all your gun shots, all without bleeding speed. With Flanker is very difficult to defend guns due to the slower responses I mentioned, its large size, and the risk of breakage during hard evasive maneuvers, and lower thrust which makes it harder to keep up the speed.

 

As for roll response, the chart in the manual says that the Flanker tops out at nearly exactly 180 degrees / second, co-incidentally at around 750 Km/h, which is also of course very close to corner speed. Can't imagine that this is a co-incidence and was probably a conscious design decision.

Keep in mind that roll response time(tied to rotational acceleration) and maximum roll rate are two different entities.. high roll rate is less helpful if it takes precious time to achieve it.

[GGTharos]

It strikes me that the best tactic against a target that's ducking and diving constantly is to... Let them do it, and observe from a safe distance. They waste energy while you don't. Easier said than done obviously, but still...

 

That's because they don't know how to jink ;)

 

Can't imagine that this is a co-incidence and was probably a conscious design decision.

It's physics supplemented by damping. Without damping you can roll quite fast at higher speeds just because of the force generated by the ailerons, subject to limits of the hydraulic forces (at some point they cannot overcome the force generated by the airflow), and the ability of the wings to actually withstand it - they are after all huge paddles and at some point they will act as giant airbrakes.

 

I know comparatively little about the Eagle but isn't it artificially limited to some insane value like 340 degrees / second?

The eagle is artificially limited to ~250deg/s, the system keeps the roll rate at that rate until is can't (ie. you're slow or high AoA and thus maximum roll rate is less). It can roll 500 deg/s + at high speed, which is probably more dangerous to the pilot than it is useful.

[DarkFire]

Keep in mind that roll response time(tied to rotational acceleration) and maximum roll rate are two different entities.. high roll rate is less helpful if it takes precious time to achieve it.

 

Ah yes, of course, roll inertia is different to roll rate, I should know better than that :doh: I agree completely that fast roll response is very useful combined with a good roll rate.

 

On the subject of guns, I vaguely remember reading somewhere that the gun on the Eagle has a built-in dispersion of some value (6 MOA sticks in my mind, no idea why) for precisely the reason that it offers a greater chance to hit a wildly maneuvering target. Can't remember where I read this but I want to say it was in the encyclopedia that came with Janes F-15E back in the day. No idea how accurate the encyclopedia was, but Janes seems to be a generally well regarded source. I also remember reading a comment by one of the designers of the MiG-29 to the effect that had they known how accurate the gun was they'd have halved the ammunition capacity!

 

The point I suppose is that for all they get compared a lot, the F-15C and Su-27 are in fact very different beasts in many respects.

[GGTharos]

It isn't about hitting wildy maneuvering target - at typical gun ranges the spread is fairly small and is intended to hit the target in many places rather than put round after round into the same hole.

[Stuge]

It isn't about hitting wildy maneuvering target - at typical gun ranges the spread is fairly small and is intended to hit the target in many places rather than put round after round into the same hole.

 

Yeah, I have to admit that after the spread was added to DCS the effectiveness of the F-15 gun went significantly up at typical ranges, with the cost losing the laser-like accuracy of longer shots :) Some spread was also added to the Russian gun.

 

But in the good old days a Flanker could snipe another Flanker's engine from 1,5 km :):):) And the engines were actually the Flanker's main weak point back in the days, thus it was wise to aim gun shots specifically at them.

[GGTharos]

That's probably far too accurate for that type of weapon and that range, going by a bit of experience from more stable gun platforms - but it's only a guess on my part :)

As for the F-15 in-game, I suspect the spread might be a bit too much, and the difference in drag between rounds is also too much I think - but again, IMHO. I haven't done any real science for this yet. :)

[SinusoidDelta]

I decided to have a look at the -34. According to it, the Eagle's M61 should have a dispersion of 90%, 8 mils at 1000ft.

 

So, at a range of 1000ft, 90% of the rounds should pass within an 8ft circle. I haven't tested this. (Honestly I'm not sure how you would)

 

IRL, the rate of fire is selectable between either 4,000 or 6,000 rounds-per-minute. Anyone know what the rate of fire is in the DCS F-15?