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

[SinusoidDelta]

There was a disagreement over which mathematical model should be used to compute drag coefficient with AoA. Those who could run CFDs to help out didn't seem to have the interest, since it's very involved.

 

What DCS has right now might be just fine though; personally I just don't like the high Cd0; the rest is guidance (there are other things regarding fuzing etc but those aren't about flight).

 

Roger that. TBH I don't have a grasp on how it's modeled now TBH. From watching the missile flyout in game it looks more like the missile is simply rotated about a point mass and less like a result of control surface deflection and resulting AoA.

 

For those asking about CD0: zero-lift drag coefficient (i.e., drag coeffecient where lift equals zero for a certain configuration, α=0 or close to it)

[D4n]

but the other 6 wings of the ET missile have 0° angle of attack (as air is coming from the side) when the other 4 are just attached to the missile and the other 2 control surfaces are set to 45° (I guess) to pull maximum turn towards target... so no drag of the wings that the air only pushes from the SIDE (not onto the surface. How "thick" are the wings, 5 mm, 8 mm ?? That's near zero drag...)

 

If Cd0 is indeed the air from front, then ok, on ET/ER it would be bit more than on normal T/R because there is a slight increase in rocket engine diameter... but other than that the ET (and other R-27) are more maneuverable than 120C (simply because of the amount of wings)

[Ktulu2]

I don't see how you proved that...

1) The aim-120 is lighter, and given you couldn't give the lift force for both missiles, we cannot compare the centripedal acceleration.

2) You assumed a 45° deflection, but it is possible that the fins would not be able to survive the drag generated at the speed in this case and 45° could only be achievable at low speeds.

3)GG said the 120 had a higher G-limit, so that would make the 120 more maneuvrable at optimal speed.

[D4n]

Why would the 120 be lighter, do you know what materials are used for 120 and R-27 ?

 

How should I calculate the lift force if the lift force is needed to calculate the lift coefficient (which is apparently needed itself again to calculate lift force... a vicious circle...) and since I am no mathematician/physicist...

[Madbrood]

The AMRAAM is around 60% of the weight of the R-27 - and that's just a ballpark figure.

[Ktulu2]

In that case, you stop saying the 27 is more maneuvrable ;)

[TAW_Blaze]

not onto the surface. How "thick" are the wings, 5 mm, 8 mm ?? That's near zero drag...)

 

Near zero my ass, almost a cm thickness can actually cause a shitload of drag especially when flown at M3-4.

[JunMcKill]

Why would the 120 be lighter, do you know what materials are used for 120 and R-27 ?

 

How should I calculate the lift force if the lift force is needed to calculate the lift coefficient (which is apparently needed itself again to calculate lift force... a vicious circle...) and since I am no mathematician/physicist...

 

R-27R/T

Specifications

Weight 253 kg (558 lb)

Length 4.08 m (13.4 ft)

Diameter 230 mm (9.1 in)

Warhead blast/fragmentation, or continuous rod

Warhead weight 39 kg (86 lb)

 

AIM-120

Specifications

Weight 335 pounds (152 kg)

Length 12 feet (3.7 m)

Diameter 7 inches (180 mm)

Warhead

High explosive blast-fragmentation

• AIM-120A/B: WDU-33/B, 50 pounds (22.7 kg)

 

• AIM-120C-5: WDU-41/B, 40 pounds (18.1 kg)

 

RVV-AE (R-77)

Specifications

Weight 175 kg (R-77), 190 kg (R-77-1)

Length 3.6 m (R-77), 3.71 m (R-77-1)

Diameter 200 mm

Warhead 22.5 kg HE fragmenting (R-77)

 

We should notice one thing, the AIM-120 is lighter, but the ER/ET speed is higher!, 4.5 mach vs 4, and the ER/ET have two stage motors in total have more burn time than AMRAAM.

 

You can use several software to calculate drag, speed or whatever for missiles, like this one:

 

http://www.aerorocket.com/AeroCFD/Instructions.html

 

https://www.grc.nasa.gov/www/k-12/InteractProgs/index.htm

 

http://www.qualitysimulations.com/rcs/manual.php

Edited July 7, 2016 by JunMcKill

[GGTharos]

R-27ER/ET

Specifications

Weight 253 kg (558 lb)

Length 4.08 m (13.4 ft)

Diameter 230 mm (9.1 in)

Warhead blast/fragmentation, or continuous rod

Warhead weight 39 kg (86 lb)

 

Shouldn't it be closer to 350Kg for the E versions?

[GGTharos]

You keep banging on that but you know, if you do the most simple math (and there must be some error in my math), you end up with this:

 

The 120 has a 1704kg thrust force which on average provides 12.9g acceleration for 8 seconds or so.

That adds 1012m/s in vacuum.

 

A similar calculation for the 27E grants a +885/s in vacuum. IMHO the R-27 has received a lot of favor in-game so please stop quoting propaganda as fact :)

 

I used the same game data that you posted, and my conclusion is: The faster, less draggy, better guided (ok, not in game), lofting 120C is going to get to you first. Or at least, it should ( the difference in top speeds is really not that great - drag should make a bigger difference but it not correctly represented IMHO, and guidance should make even more of a difference, and ED is working on that one)

 

We should notice one thing, the AIM-120 is lighter, but the ER/ET speed is higher!, 4.5 mach vs 4, and the ER/ET have two stage motors in total have more burn time than AMRAAM.

Edited July 7, 2016 by GGTharos

[JunMcKill]

Shouldn't it be closer to 350Kg for the E versions?

 

Yeah, you're right

[JunMcKill]

You keep banging on that but you know, if you do the most simple math (and there must be some error in my math), you end up with this:

 

The 120 has a 1704kg thrust force which on average provides 12.9g acceleration for 8 seconds or so.

That adds 1012m/s in vacuum.

 

A similar calculation for the 27E grants a +885/s in vacuum. IMHO the R-27 has received a lot of favor in-game so please stop quoting propaganda as fact :)

 

I used the same game data that you posted, and my conclusion is: The faster, less draggy, better guided (ok, not in game), lofting 120C is going to get to you first. Or at least, it should ( the difference in top speeds is really not that great - drag should make a bigger difference but it not correctly represented IMHO, and guidance should make even more of a difference, and ED is working on that one)

 

Reading what you post, mean that Russian scientists are dumb, they never discovered or built a decent wind tunnel and were coincidentally the first to reach the cosmos, and have the best rocket engines by sheer coincidence, they sent the more stupid guys for the military! ohhhh god!!! If the manufacturer say their missile reach 4.5 mach and +90km range is with the missile drag/weight already calculated!

[Ktulu2]

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAnd welcome Digital Falcon Simulator talk

 

Also, JunMcKill You have to expect public capacities to be quite optimistic... IF manufacturer stats are true, they are only in super optimal situations that are improbable in combat (i.e. mach 2 launch : 2+885/333~4.5)

[SinusoidDelta]

I can't tell if you're being sarcastic or what you're trying to imply Jun. There are two threads I linked below. I'd advise anyone interested in hacking out the math to check them out. They actually reference the missile analysis paper by IASGATG for some details. Page 2 of the keypub thread has an excellent excel spreadsheet for estimating missile maneuverability.

http://www.f-16.net/forum/viewtopic.php?f=38&t=28234&sid=0215c897e75ab87672471eb940cf7c2a

 

http://forum.keypublishing.com/showthread.php?137398-What-factors-affecting-aircraft-missiles-sustained-turn-rate

[GGTharos]

You're reading way too much into it.

 

It has nothing to do with scientists being clever or not.

 

It has everything to do with launch parameters, and the probable parameters that the various manufacturers are not conforming to any sort of standard when making such reports.

 

You don't know if you're getting the same altitude, the average case, the maximum case, something inbetween ...

 

As an example, the USN tactics manuals specifify that the AIM-120A top speed is '4 mach numbers above launch mach"

 

... so AIM-120A is suddenly a Mach 4.5 missile when launched at Mach 0.5, so I guess ED has got things very, very wrong? I mean it's written in a USN manual, not on some wikipedia on the internet, right? :)

 

Besides which, why are you arguing with the math? Who cares what the manufacturer writes - and that's the whole point. Unless you have a speed-time diagram, you have to figure out the flight profile yourself, so quoting 'Mach 4.5' from a single row off some table is quite meaningless as a figure of comparison.

 

 

Reading what you post, mean that Russian scientists are dumb, they never discovered or built a decent wind tunnel and were coincidentally the first to reach the cosmos, and have the best rocket engines by sheer coincidence, they sent the more stupid guys for the military! ohhhh god!!! If the manufacturer say their missile reach 4.5 mach and +90km range is with the missile drag/weight already calculated!

[JunMcKill]

Can someone post here a single page of a real R-27ER russian document (or translated/exported) contradicting the 4.5 mach that all analyst post in their web pages about the missile? in that case, I will take what you post for real!. AFAIK, the 65.5 km range is against a fighter size aircraft flying at your own altitude (in this case a maneuverable target), and for bigger aircrafts can kill at 90km

 

You're reading way too much into it.

 

It has nothing to do with scientists being clever or not.

 

It has everything to do with launch parameters, and the probable parameters that the various manufacturers are not conforming to any sort of standard when making such reports.

 

You don't know if you're getting the same altitude, the average case, the maximum case, something inbetween ...

 

As an example, the USN tactics manuals specifify that the AIM-120A top speed is '4 mach numbers above launch mach"

 

... so AIM-120A is suddenly a Mach 4.5 missile when launched at Mach 0.5, so I guess ED has got things very, very wrong? I mean it's written in a USN manual, not on some wikipedia on the internet, right? :)

 

Besides which, why are you arguing with the math? Who cares what the manufacturer writes - and that's the whole point. Unless you have a speed-time diagram, you have to figure out the flight profile yourself, so quoting 'Mach 4.5' from a single row off some table is quite meaningless as a figure of comparison.

[GGTharos]

Can someone post here a single page of a real R-27ER russian document (or translated/exported) contradicting the 4.5 mach that all analyst post in their web pages about the missile?

 

Can you post one page of real US documentation contradicting Mach 4.0 + Aircraft Speed AMRAAM?

 

Anyway, I just posted the analysis above, and you can do the math yourself.

 

in that case, I will take what you post for real!. AFAIK, the 65.5 km range is against a fighter size aircraft flying at your own altitude (in this case a maneuverable target), and for bigger aircrafts can kill at 90km

 

I don't know that anyone was disputing that ... in fact it's pretty easy to prove that the AIM-7 can make that 66km kill ... and the 90 one, too so ... what does this have to do with top speed? :D

[JunMcKill]

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

 

Can you post one page of real US documentation contradicting Mach 4.0 + Aircraft Speed AMRAAM?

 

Anyway, I just posted the analysis above, and you can do the math yourself.

 

 

 

I don't know that anyone was disputing that ... in fact it's pretty easy to prove that the AIM-7 can make that 66km kill ... and the 90 one, too so ... what does this have to do with top speed? :D

[Ktulu2]

If you go back two pages, you'll see that R27 can get to that speed in game...

You just need the good launch conditions

[JunMcKill]

If you go back two pages, you'll see that R27 can get to that speed in game...

You just need the good launch conditions

 

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

[Ktulu2]

Try an unguided launch maybe

[JunMcKill]

Try an unguided launch maybe

 

All launch were tested unguided in overwrite mode, the R-77 max speed was ok, reach 3.9982 mach (4301.4898 TAS), the problem with the R-77 is that began bleeding speed too quick while in transonic, and should be in subsonic!.

[D4n]

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?

[Ktulu2]

Son, you're writing checks your rep can't cash...

 

Seriously, 1) The 27 has bigger fins and fuselage as you said, that leaves a higher ''empty'' wight.

2) Again, 120 has it for G-limit

[D4n]

What means "sth has it for sth." ? (sry not native english speaking, I'm german)

Edited July 7, 2016 by DanielNL