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Tactics against low flying Su27s


OnlyforDCS

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Ditching your altitude advantage isn't gonna help you win the fight. Against a flanker with such a height disadvantage you can usually keep pushing without ever turning cold, it's just a matter of sacrificing another missile. A shot from slightly above 10 nm can force him to turn by the time his ER could get close and the ET's are really easy to dodge. After that there isn't a lot he can do because you'll be closing the gap while he's busy turning, in a clean scenario where you can chase if he ever tries to recommit he'll be under 7 miles and that's a definite kill while you can just turn around before he even gets the angles to have a good shot.

 

Not the usual approach on the server because it costs atleast 2 missiles to get one guy and if he just runs away you won't be able to catch him.

 

You should probably fly MP instead though, fighting the AI is pretty useless.

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As far as AAMs go, what the guidance does with the glidepath matters. In this game, no such thing is done. And it will give you a huge range advantage.

 

In other words, your conclusions are completely incorrect with respect to realism (but correct for this game), due to factors that you do not control.

 

The range advantage would still be due to missile taking less draggy flight path instead of having more energy due to flying downhill if I understood correctly? Wouldn't this be possible also in the uphill shot where missile first climbs to higher flightpath before steering for intercept?

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Less draggy path is one reason, though there's more to it - for example a missile that controls its glidepath can aim to maintain speed. Also I don't believe missiles should be as draggy as they are in-game - meaning to me, RF missiles appear to have the drag of IR missiles, thus causing them to suffer more than they ought to, especially at low altitudes.

 

AFAIK, there are 'snap up' and 'snap down' launch profiles, where within certain range there might not be an inherent advantage for a high-low vs low-high shot, but on the other hand, low-high should just about never have an advantage over high-low, and generally should be shorter ranged: The low-high shot is fighting higher drag in the climb-out for the first few seconds, and gravity throughout its flight. The high-low shot gets the advantage of working with gravity on its way down.

 

As far as SAMs going into orbit and dropping back down, those things come with huge boosters whose purpose is to get them 'up there'. For AAMs, the booster is the launching aircraft.

 

All IMHO.

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Reminder: SAM = Speed Bump :D

I used to play flight sims like you, but then I took a slammer to the knee - Yoda

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The range advantage would still be due to missile taking less draggy flight path instead of having more energy due to flying downhill if I understood correctly? Wouldn't this be possible also in the uphill shot where missile first climbs to higher flightpath before steering for intercept?

 

The high missile not only has more energy by going downhill, but by starting higher. You can find out exactly how much energy a missile gains from the launch platform.

 

Launch platform additional energy = missile_mass*gravity*altitude_above_target + .5*missile_mass*launch_speed^2

 

The missile with higher energy can choose to fly higher (less drag) or reach speed faster. It's not straightforward to convert energy to range because drag limits how much energy the missile can carry.

Awaiting: DCS F-15C

Win 10 i5-9600KF 4.6 GHz 64 GB RAM RTX2080Ti 11GB -- Win 7 64 i5-6600K 3.6 GHz 32 GB RAM GTX970 4GB -- A-10C, F-5E, Su-27, F-15C, F-14B, F-16C missions in User Files

 

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Ditching your altitude advantage isn't gonna help you win the fight. Against a flanker with such a height disadvantage you can usually keep pushing without ever turning cold' date=' it's just a matter of sacrificing another missile.[/quote']

 

Yes I realize thats how it should be, but currently it's not the way it seems to be working. Their missiles reach me before mine reach them, and they get a higher pk shot with an earlier LA. I get LA at about 12 nm, against them. Against targets at co altitude in the F15C NTTR provided instant action mission I get LA at 20nm or more.

 

The funny thing is the first time I tried the mission, I took about five minutes longer to get in the air and on station. By that time the Su27 seperated from the strike package and went higher. I had no trouble dispatching both (although they did get my wingman).


Edited by OnlyforDCS

Current specs: Windows 10 Home 64bit, i5-9600K @ 3.7 Ghz, 32GB DDR4 RAM, 1TB Samsung EVO 860 M.2 SSD, GAINWARD RTX2060 6GB, Oculus Rift S, MS FFB2 Sidewinder + Warthog Throttle Quadrant, Saitek Pro rudder pedals.

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Actually the values used in the game (total propellant mass, propellant mass/sec flow rate per stage, stage duration in seconds) will get you in the ball-park of the correct delta-v in the game. You can find this information in missiles_data.lua.

 

And AFAIK, one accounted for and two un-accounted for effects:

1) Rocket motor thrust increases with altitude (+7% or so by the time you hit 12000m) is accounted for

2) Rocket motor operation eliminates tail drag (about 20% of the Cd) is not accounted for

3) Rocket motors are tuned to provide maximum performance at a given altitude (This is rocket nozzle configuration, and gives higher thrust than otherwise expected 'by the numbers' that are available to us) ... also not accounted for and maybe never will be since we don't know which altitude each rocket motor is tuned for

 

The post ShuRugal is quoting is neat, but sickeningly inaccurate (and I used to refer to that post, until I decided to 'do the math' and read up on tactical missile design, as well as finding solid sources for propellant mass).

 

You can find results from an AIM-120C CFD in IASGATG's missile mod thread ... generally the 120A/B/C4 curve after burn-out will be nearly the same, just starting at a lower top speed.

 

What would be a good comparison is the delta-v of the missile's rocket engine. This is the value which excludes the effect of atmospheric drag, or in other words, the value by which the missile would accelerate if fired in space.

 

This comparison would provide a percentage value of how much the launch altitude of the missile really matters.

 

Maybe you know the delta-v value of AIM-120C, GGTharos?

[sIGPIC][/sIGPIC]

Reminder: SAM = Speed Bump :D

I used to play flight sims like you, but then I took a slammer to the knee - Yoda

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Quick calculation of energies gives a ~140m/s advantage to Mach 4 missile fired downwards from 10km altitude vs upwards the same trajectory based on pure energy alone disregarding drag (end speed 1430 m/s vs. 1286 m/s). Basically the potential energy (gravity assist) from altitude is pretty small compared to the kinetic energy of the missile when speaking of modern BVR missiles that reach speeds in excess of Mach 4. In practice in DCS I have measured about 2 nm range advantage to the guy firing down from 20k feet vs. firing up when both of their their missiles have slowed down to Mach 2. It's still much easier for the low guy to trash the high guys missile vs. vice versa though so the 2nm advantage is even smaller in practice.

 

 

Matlab output:

>> g = 9.81;

 

>> h = 10000;

 

>> v = 340*4;

 

>> m = 300;

 

>> Ep = g * h * m

 

Ep = 29430000

>> Ek = 0.5 * m * v * v

 

Ek = 277440000

>> E1 = Ep + Ek

 

E1 = 306870000

>> E2 = -Ep + Ek

 

E2 = 248010000

>> v1 = sqrt(2*E1/m)

 

v1 = 1430.3

>> v2 = sqrt(2*E2/m)

 

v2 = 1285.8

>> deltav = v1 - v2

 

deltav = 144.47

 

DCS Finland: Suomalainen DCS yhteisö -- Finnish DCS community

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Yes I realize thats how it should be, but currently it's not the way it seems to be working. Their missiles reach me before mine reach them, and they get a higher pk shot with an earlier LA. I get LA at about 12 nm, against them. Against targets at co altitude in the F15C NTTR provided instant action mission I get LA at 20nm or more.

 

The funny thing is the first time I tried the mission, I took about five minutes longer to get in the air and on station. By that time the Su27 seperated from the strike package and went higher. I had no trouble dispatching both (although they did get my wingman).

 

It works exactly like I said. The higher you are the further the missiles go, dumpstering your position over a bandit on paper is the worst tactical move you could pull.

 

The effect of altitude, air density and drag on missile ranges might be overall bullshit compared to what it should be but it still works. If it's not working for you then it's your fault, not the system's. If you run into a guy who's waving at you from 1 kft and you're sitting in your sofa at 20 kft ish and his missile gets to your first then you really have no idea what you're doing. Not to mention we're speaking of AI.

 

LA and DLZ are irrelevant in the game. They're not even close to an approximate of what the missile can do. Your best bet is to know from experience what they can do and act on it. The point of having all the eye candy in your cockpit is to gather information and make use of it :)

 

If you upload some tacviews I can have a look and tell you what you should be doing but I really can't be bothered to record tracks.

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...I get LA at about 12 nm, against them. Against targets at co altitude in the F15C NTTR provided instant action mission I get LA at 20nm or more....

I imagine that's because the altitudes involved are significantly different.

 

Unfortunately, I haven't been in a position to review your track but a simple question; 2 questions, really. 1) Where is your nose pointing, when you launch? and 2) What are you doing to minimize the range closure after you have launched?

 

One possibility is that you are forcing your missiles to maneuver significantly as they comes off the rails because you nose is too far off bore and, so, they lose a lot of energy right from the start. Then, after you launch, you need to maximize the time it takes for any missiles the Flankers might put into the air to get to you by slowing the closure rate.

 

Just some thoughts...

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You bring up some good points Ironhand. Ill make sure to put enemy planes at gimbal limits after launch and fire nose on target.

 

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Pretty much the "snake" dance like Sweep suggested. It's harder with TWS due to the smaller scan zone. But since its the AI we are talking about maybe I should just concentrate on locking up one of them at a time with an STT lock first.

Current specs: Windows 10 Home 64bit, i5-9600K @ 3.7 Ghz, 32GB DDR4 RAM, 1TB Samsung EVO 860 M.2 SSD, GAINWARD RTX2060 6GB, Oculus Rift S, MS FFB2 Sidewinder + Warthog Throttle Quadrant, Saitek Pro rudder pedals.

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Pretty much the "snake" dance like Sweep suggested. It's harder with TWS due to the smaller scan zone. But since its the AI we are talking about maybe I should just concentrate on locking up one of them at a time with an STT lock first.

I'm a little confused by the purpose of the "snake" dance prior to launch--to what purpose? It complicates you life while having minimum effect on the outcome. Or am I missing something? Given the situation, you have the longer reach to start with, don't you?

 

I would practice with TWS rather than a hard SST, I think.

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I ****ing hate this shit system with the auto logout losing whole posts all the time if I accidentally click somewhere else other than re-login. Seriously **** that.

 

Well in short if you're in a 1v2 you either wanna offset one so you have time to deal with 1 before the other arrives (this obviously doesn't work if they're close), or you have to take both at the same time. Then you wanna screw them on the first shot because if they're still alive after your initial volley then you don't really stand a chance.

 

Snaking before launch is useless on paper, you're dumping energy instead of banking it. Better to stay calm and analyze the environment, pick a direction you want to crank towards and then plan your fight from there. If you have to fight 2 guys at once you'd better be stashing as much energy as you can because if you don't get shit done in the first shot chances are extremely high you'll have to run back to base anyway (if you even get the chance).

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Does paper fly, Blaze? :D

 

TBH, if you're 1v2 you might as well keep your energy and run off.

 

My point with snaking is that you can bleed down the threat missiles energy and increase TTI...whatever energy you bleed (you won't bleed much...) doesn't matter because I recommended a split S as soon as your Slammers are active.

 

Honestly, I think having a basic idea of what you should do and practicing it on a server is the best idea...the AI isn't that great for learning stuff from...IMO.

Lord of Salt

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...

My point with snaking is that you can bleed down the threat missiles energy and increase TTI....

That I understand and agree that, once their missiles are in the air, it becomes useful. But it almost sounds as if he's doing it prior to enemy missile launch.

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That I understand and agree that, once their missiles are in the air, it becomes useful. But it almost sounds as if he's doing it prior to enemy missile launch.

 

If that is what is happening, snaking before there is a missile in the air is a very bad idea, for two reasons: First, you are bleeding energy to no purpose. Second, if you are not hot aspect to your bandit, his fire control computer is going to tell him that his rMax is shorter. Since the AI always launches their first missile at rMax, this puts you deeper into his kill box when he finally does launch.

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:)

 

The reason I said on paper because in practice any move can be good. In some cases you have to do the most unreasonable things to throw the guy off. But that only works if you know the basics real good.

 

I agree on the fact that training on the AI is a bad idea. It'll teach you habits that won't make any sense to pull off against players and it'll be hard to unlearn them.

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Quick calculation of energies gives a ~140m/s advantage to Mach 4 missile fired downwards from 10km altitude vs upwards the same trajectory based on pure energy alone disregarding drag (end speed 1430 m/s vs. 1286 m/s). Basically the potential energy (gravity assist) from altitude is pretty small compared to the kinetic energy of the missile when speaking of modern BVR missiles that reach speeds in excess of Mach 4. In practice in DCS I have measured about 2 nm range advantage to the guy firing down from 20k feet vs. firing up when both of their their missiles have slowed down to Mach 2. It's still much easier for the low guy to trash the high guys missile vs. vice versa though so the 2nm advantage is even smaller in practice.

 

 

Matlab output:

>> g = 9.81;

 

>> h = 10000;

 

>> v = 340*4;

 

>> m = 300;

 

>> Ep = g * h * m

 

Ep = 29430000

>> Ek = 0.5 * m * v * v

 

Ek = 277440000

>> E1 = Ep + Ek

 

E1 = 306870000

>> E2 = -Ep + Ek

 

E2 = 248010000

>> v1 = sqrt(2*E1/m)

 

v1 = 1430.3

>> v2 = sqrt(2*E2/m)

 

v2 = 1285.8

>> deltav = v1 - v2

 

deltav = 144.47

 

Looks like my Delta V calculation was made with an incorrect logic, thanks for pointing it out Bush! It all makes much more sense now, too...

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The difference should increase based on induced drag to climb as well, but the diving missile needs guidance that supports seriously using that gravity advantage by reducing induced drag (controls set up to lower AoA in the dive). Path choice also makes a difference, but this is all N/A DCS for now.

[sIGPIC][/sIGPIC]

Reminder: SAM = Speed Bump :D

I used to play flight sims like you, but then I took a slammer to the knee - Yoda

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EDIT: my delta v calculation was incorrect, disregard this one :)

 

Using Delta V lets you get the % of energy from speed/climb relative to total fuel energy, but ignoring the effect of drag will still cause issues. Basically, the total energy is your mileage under the absolute best conditions. But that limit isn't the real limit because you have a certain maximum performance on the launch platform and the missile itself. Within those limits, your flight path controls how much energy you can actually use. Relative to total energy, the height and speed advantage should make a bigger difference than raw %'s.

 

Yes I realize thats how it should be, but currently it's not the way it seems to be working. Their missiles reach me before mine reach them, and they get a higher pk shot with an earlier LA. I get LA at about 12 nm, against them. Against targets at co altitude in the F15C NTTR provided instant action mission I get LA at 20nm or more.

Even if missiles don't quite work correctly, height gives you options. For one thing, launch speed is probably more important than alt in DCS and max speed is usually reached at height. Altitude can also be converted to speed, and speed itself is a good missile defense.

 

You can also exercise control over missile launched against you. You can force a missile launched from down low to stay low by diving. You can also force it to overshoot up by climbing and then reverse into a dive. It may end up flying to high/slow to follow you.

Awaiting: DCS F-15C

Win 10 i5-9600KF 4.6 GHz 64 GB RAM RTX2080Ti 11GB -- Win 7 64 i5-6600K 3.6 GHz 32 GB RAM GTX970 4GB -- A-10C, F-5E, Su-27, F-15C, F-14B, F-16C missions in User Files

 

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Looks like my Delta V calculation was made with an incorrect logic, thanks for pointing it out Bush! It all makes much more sense now, too...

 

I'm not sure if my calculation makes more sense if you think carefully about it. I was calculating difference in speed between uphill launch and downhill launch between sea level and 10km altitude, not deltav from the engine. Your calculation was correct for a missile dropped from standstill but it's different when the missile is already going very fast. The difference would be greater if the missile in question had smaller initial speed.

 

It might be very hard to wrap your head around the concept that speed gain is smaller when when you already have some initial speed but that's how it works. Basically gravity has less time to accelerate the missile and/or the velocity components are not parallel to each other due to the path used so they don't add up arithmetically. I actually calculated the speed difference with both of these ideas and got the same result as with using energy principle.


Edited by Bushmanni
Changed perpendicular to parallel.

DCS Finland: Suomalainen DCS yhteisö -- Finnish DCS community

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