MiG-29S EOS flying at 4000m not detecting F-15 that's straight hot and very low

[TAW_Blaze]

I did the test many times with friends with the same conditions, we were flying at 10,000 MSL, 900 km/h, head to head with no change in speed and course, tha max speed of R-27ER was match 4.2, 4527.88 kph

 

It can reach 4.5 just fine, 10 km MSL at 900 km/h is shit. If you're not doing M1+ at that alt in BVR you might aswell pull the ejection handle. ER actually has quite the edge at space invader shootouts where drag is close to nonexistent compared to low / med alt. The main reason people don't do this much is because guidance sucks and you often can't rely on your ERs even in a 1v1.

 

But the R-27 ET weighing more than 120C at launch doesn't necessarily mean that the ET will still weighs more than 120C after engine-cut off... (ET most probably carrying more kg of fuel) So the ET will be more maneuverable than 120C due to it having more wings right?

 

ET is way draggier than an ER because it has a flat IR seeker instead of a radar cone that's got actual aerodynamics. Fin size has nothing to do with maneuverability at optimal speeds. Like others already said AMRAAM has a higher G limit than the 27 despite having smaller fins. At M3-4 the limiting factor is the structural strength. Around M1 big fins will give you a better turning capability but that's useless because you'll never catch the target at that point.

[D4n]

ET is way draggier than an ER because it has a flat IR seeker instead of a radar cone that's got actual aerodynamics.

 

About how much % does the round top of the missile actually increase drag compared to the sharp top of the radar cone? Isn't it just like sth. (rouglhy in the range of) 2-20% or so? (again I'm not a physicist) after all the round IR seeker isn't flat and a round object will still push away air to the sides...

 

Fin size has nothing to do with maneuverability at optimal speeds. Like others already said AMRAAM has a higher G limit than the 27 despite having smaller fins. At M3-4 the limiting factor is the structural strength. Around M1 big fins will give you a better turning capability but that's useless because you'll never catch the target at that point.

 

 

I meant like Mach 2-2.5 from the situation in my tacview video (page 10), where if the two control surfaces turned by 45° I strongly believe that the ET would've made a harder turn that just 10.7 g...

 

Also why not at M1, if a target is still hot after launch... (maximum distance launch)

[Ktulu2]

the general formula for drag is 1/2*Cd*p*S*v²

 

Let's say we have a 1% increase in drag, at mach 3 (1000m/s) that one percent becomes

1.01*v² instead of v² (assuming everything else =1, just to make it simple and prove my point)

1.01*10^6 vs 1*10^6, in metric that's a difference of 10^4N, OR 1/10 of the hornet's military thrust.

 

Of course, the numbers are fictionnal, but the point stays : AT HIGH SPEED, THE SLIGHTET DRAG DIFFERENCE MATTERS

 

Also, the drag coeff. of a plane perpendicular to the flow is ~2, vs ~.5 for a sphere. These are from wikipedia and mostlikely sub-sonic, but still gives you an idea.

 

BTW 20% Cd increase would make the missile like Ed's R-550

Edited July 8, 2016 by Ktulu2

[Sweep]

the general formula for drag is 1/2*Cd*p*S*v²

 

Let's say we have a 1% increase in drag, at mach 3 (1000m/s) that one percent becomes

1.01*v² instead of v² (assuming everything else =1, just to make it simple and prove my point)

1.01*10^6 vs 1*10^6, in metric that's a difference of 10^4N, OR 1/10 of the hornet's military thrust.

 

Of course, the numbers are fictionnal, but the point stays : AT HIGH SPEED, THE SLIGHTET DRAG DIFFERENCE MATTERS

 

Also, the drag coeff. of a plane perpendicular to the flow is ~2, vs ~.5 for a sphere. These are from wikipedia and mostlikely sub-sonic, but still gives you an idea.

 

BTW 20% Cd increase would make the missile like Ed's R-550

 

[GGTharos]

ED didn't assume anything. They just programmed the known data of the rocket motor into the game, as well as the presumed drag.

 

If you want to complain that that the drag coefficients are high, I agree ... they are high for all RF missiles :)

 

I dont have to post anything is ED who assume that 4.5 is not the real speed not me!

[GGTharos]

But the R-27 ET weighing more than 120C at launch doesn't necessarily mean that the ET will still weighs more than 120C after engine-cut off...

 

No, it pretty much does mean that. AAMs have 28-34% of their mass as rocket fuel as a rule of thumb.

 

(ET most probably carrying more kg of fuel) So the ET will be more maneuverable than 120C due to it having more wings right?

 

Nope. It has no ability to match the 120C in maneuverability. It's airframe is limited to 24g.

 

That's like saying the AIM-7 is more maneuverable than the AIM-120 ... we know it's not.

[GGTharos]

About how much % does the round top of the missile actually increase drag compared to the sharp top of the radar cone? Isn't it just like sth. (rouglhy in the range of) 2-20% or so? (again I'm not a physicist) after all the round IR seeker isn't flat and a round object will still push away air to the sides...

 

It makes a huge difference; how much exactly? You have to dig in and do the math, but last time I checked it was pretty big. The drag coefficient for a round nose can be 40% higher (sometimes more) of the drag coefficient of the typical ogive radar domes.

 

I meant like Mach 2-2.5 from the situation in my tacview video (page 10), where if the two control surfaces turned by 45° I strongly believe that the ET would've made a harder turn that just 10.7 g...

I have no idea why you think it would 'more maneuverable', as that isn't even the issue. It probably wouldn't be wrong to expect 1g per mach number as a rule of thumb, but ... can you prove it?

 

Also why not at M1, if a target is still hot after launch... (maximum distance launch)

No one in the business really talks about AAMs that slow. It's really on the edge of controllability. SAMs for example are typically locked down until they reach a certain speed - maneuvering using the fins before that time can cause stalls and other unpleasant things.

[JunMcKill]

It can reach 4.5 just fine' date=' 10 km MSL at 900 km/h is shit. If you're not doing M1+ at that alt in BVR you might aswell pull the ejection handle. ER actually has quite the edge at space invader shootouts where drag is close to nonexistent compared to low / med alt. The main reason people don't do this much is because guidance sucks and you often can't rely on your ERs even in a 1v1..[/quote']

 

I did my homework:

 

first test

R-27ER launched at 10,100 MSL and 1,080 km/h (mach 1.0)

Max speed of the missile at 10,101 MSL was 4,684 km/h (mach 4.351216)

 

second test

R-27ER launched at 11,245 MSL at 1,158 km/h (mach 1.09)

Max speed of the missile at 10,682 MSL was 4,828 km/h (mach 4.5235399)

[D4n]

Nope. It has no ability to match the 120C in maneuverability. It's airframe is limited to 24g.

 

"it's" being the 120C or 27 ? If u mean 27, well than the question remains to why my ET didn't pull harder than 10.7 g at that moment...

 

 

That's like saying the AIM-7 is more maneuverable than the AIM-120 ... we know it's not.

 

You guys know? May I know your source? The only reasons I could imagine would be that the AIM-7 wings wouldn't go up to 45° angle because of material reasons, that they didn't have strong enough metal 30 years ago (that the wings would break at 45° and Mach 2) and that today the 120C has far stronger metal in the wing-rocket body connection and thus would have no problem with the force of the air at 45° Mach 2... (or would you quote (an)other reason(s)?)

 

What do you mean about "1g per mach number" ? That a missile can only take 10.7 g at mach 2 and more than 11 g at mach 1 ? Because of what, too weak missile-control-surface materials?! :P (I highly doubt it!)

 

And what would happen if an AAM goes "only" 1000 km/h / Mach 1 (engine off), would it already start dropping from the sky because of not enough lift at that speed (and the missile being more than 100 Kg)? (I could imagine)

 

 

Ktulu what about Ed's R-550 ? Anything special? (Haven't looked into the values)

[Ktulu2]

The concept from a G limit is that the missile cannot whitstand a higher acceleration, not necesserely the force required for the acceleration : The fins might be fine at Mach 2 at 45° (Which I super-highly doubt, see time wasted below), but the radar/electronics/fuselage might break at that G.

 

The ED's 550 was a joke, there's a video of a guy shooting one and keeping on flying strait and getting killed by his own missile because there was WAYYYYYYYYYYYYYYYY too much drag.

[D4n]

"see time wasted below" ? Below what?

 

So it was purely coincidence that you made a hard left turn at the moment my ET was that close to you? (tacview video) :P

 

Then also what is the technical explanation for my missile not keeping the 10.7 g up until it missed you? (already at 300 m distance between my ET and you it started decreasing in g...? You were still in seeker angle...)

 

It already passed by 50m, considering my ET had KEPT turning at 10.7 g it would've gotten even closer to you... (within distance of proximity-trigger warhead fragments would have hit your ac)

Edited July 8, 2016 by DanielNL

[Ktulu2]

All right 1st :

fin of the 120 dimentions :

http://www.f-16.net/forum/viewtopic.php?f=38&t=28234&start=15

 

I'll take in consideration that 1 of the front fin is doing 45 of AoA.

Aspect ratio : height/base :0.133/0.266=½

 

Cl=2pi*AoA in Rad = 2pi*(45/360*2*pi)=4.935

according to here : http://wright.nasa.gov/airplane/lifteq.html

 

Here, parasitic drag is highly negligeable compared to induced, so

Cd~Cl²/(pi*AR*e) e is usually around 1 : https://en.wikipedia.org/wiki/Lift-induced_drag

 

SO Cd ~ 4.93²/(pi*½*1)= 15.5 (WEIRD... VERY HIGH)

 

Surface = 0.114m²

 

SO at mach 2 drag = ½*Cd*p*S*v²=1/2*15.5*1.1*0.144*666²=544509N

Lift=½*Cl*p*S*v²=1/2*4.93*1.1*0.144*666²=173189N

Total force = (L²+D²)^½=1/2*4.93*1.1*0.144*666²=571388N=58 304Kgf

 

Now, thats a lotta jets burners concentrated onto a single tiny winglet, so no way in the world it survives that (2.2 F-15s)

 

Now, i'm starting my aerospace bachelor in 2 months, so there are probably mistakes in here as i'm no qualified, but its the best I can do and i'm pretty sure its a decent approximation.

 

(sorry this is wasted time, just didnt want to delay my post ;) )

[Ktulu2]

Yeah, many (including me!) are saying that guidance is the problem in DCS, especially on russian missiles.

[D4n]

Wow, but what do you mean "survives that" ? The wing would break or what u mean? 2.2 F-15s, what is "2.2" ?

[Ktulu2]

Yes, there's the thrust of 2.2 F-15s concentrated on the winglet, so I HIGHLY doubt the wing would resist it.

[GGTharos]

But go with the more typical 15 deg deflection and you get about 40gs of normal force. You likely won't even need that much to accomplish whatever you're trying to do, and can probably go with a reasonable 8-10 deg :)

[Ktulu2]

I know, was just trying to prove that 45° is irrelevent for calculations of the maneuvrability of a missile.

[D4n]

Ah understand. So Tharos, what do you think why the ET stopped keeping up the 10,7 g turn in the tacview? (as I stated, the missile wouldn't even need impact the target if the warhead just goes of within 30 meters or so)

 

Or is the ET currently not programmed with proximity fuze in DCS?

[Seaeagle]

The published range of the R-27's radar proximity fuze is 11 m.

 

AFAIK this is also the range implemented in DCS.

Edited July 8, 2016 by Seaeagle

[D4n]

I mean the optical proximity fuze (when the target has reached a specific size).

[JunMcKill]

The published range of the R-27's radar proximity fuze is 11 m.

 

AFAIK this is also the range implemented in DCS.

 

Yes, is the same in DCS for R-27ET

 

KillDistance = 11.0,

[Seaeagle]

I mean the optical proximity fuze (when the target has reached a specific size).

 

There is no such thing :)

 

The warhead is the same on all R-27 versions and is detonated either by the proximity fuze(radar) or by impact fuze.

[Seaeagle]

Yes, is the same in DCS for R-27ET

 

KillDistance = 11.0,

 

Cool - thanks for confirmation :)

[DarkFire]

OK, I did two further possibly more representative tests, one using the R-27ER (x2, and 2xR-73, and cannon fire, let's not go there :disgust: ) and the second using the R-27ET.

 

For both tests I was at 10,000m altitude approaching head-on to a KC-135 which was at 1,500m altitude and 650 Km/h TAS. In each case I was up at 10,000m and had been accelerating in maximum AB for some minutes.

 

For the R-27ER test, I launched at a range of 52.2 Km. My speed was 2,380 Km/h = M2.2. The missile immediately performed a 9.1G push-over and descended towards the target. It bled off so much speed that it eventually kinematically failed to reach the target, falling short by maybe 20m or so and passing under the target. Close enough to be considered representative of a successful missile flight path. The missile reached a maximum speed of 5,086 Km/h = M4.63 at 8,686m ASL.

 

For the R-27ET test, I launched at a range of 34.2 Km. It should be noted that it was only at this point that the missile seeker acquired the target and in terms of range this was close to being a launch at Rtr. At the time of launch I was at 2,225 Km/h = M2.06. In this case the missile immediately performed a 12G push-over and again descended towards the target which was subsequently directly hit. The missile reached a maximum speed of 4,665 Km/h = M4.30 at 9,548m ASL.

 

For anyone wanting to plot the missile flight profiles, the ACMI files are attached.

[JunMcKill]

Good test Darkfire, unless the variable LifeTime inside the missile_data.lua is set to 60, the ER missile should hit the target, you had lock all the time until 13:14, but the missile was fubar anyway. And if you notice you launched the missile at 52.5 km away, and even coming from above the missile could not reach 40 kms with a good speed!

 

OK, I did two further possibly more representative tests, one using the R-27ER (x2, and 2xR-73, and cannon fire, let's not go there :disgust: ) and the second using the R-27ET.

 

For both tests I was at 10,000m altitude approaching head-on to a KC-135 which was at 1,500m altitude and 650 Km/h TAS. In each case I was up at 10,000m and had been accelerating in maximum AB for some minutes.

 

For the R-27ER test, I launched at a range of 52.2 Km. My speed was 2,380 Km/h = M2.2. The missile immediately performed a 9.1G push-over and descended towards the target. It bled off so much speed that it eventually kinematically failed to reach the target, falling short by maybe 20m or so and passing under the target. Close enough to be considered representative of a successful missile flight path. The missile reached a maximum speed of 5,086 Km/h = M4.63 at 8,686m ASL.

 

For the R-27ET test, I launched at a range of 34.2 Km. It should be noted that it was only at this point that the missile seeker acquired the target and in terms of range this was close to being a launch at Rtr. At the time of launch I was at 2,225 Km/h = M2.06. In this case the missile immediately performed a 12G push-over and again descended towards the target which was subsequently directly hit. The missile reached a maximum speed of 4,665 Km/h = M4.30 at 9,548m ASL.

 

For anyone wanting to plot the missile flight profiles, the ACMI files are attached.

Edited July 8, 2016 by JunMcKill