AMRAAM G load

[borg]

Aren't the R-33M slightly redesigned with smaller fins though..?
Perhaps lighter seeker warhead etc.

[basher54321]

may be the reason that older missiles like AIM-9B are not effective is that they can only turn maximum of 10G thus cant intercept anything that turn more than G

I would put that further down the list e.g.

Launch parameters for the AIM-9B were highly restrictive - not good enough to just lock onto a tail pipe - you had to be pretty much unloaded to launch the missile.
If you consider that most jets had nothing more than a higher tone audio growl (no info in HUDs) as feedback and had to estimate the rest - not an easy job in the 50/60s - especially if you add the stress of combat into it.

Then you have the seeker head happily locking onto the sun / clouds / sea / ground.

Also reliability of the hardware was affected by vibration of handling/flight and the weather/environment.

[armedupdate]

Is it better to use 6 G turns to defeat a missile like the AMRAAM or do 9 G turns? Because 9 G turns although the turn is much tighter is depletes energy faster, plus it won't probably cover as much distance singe the turn is so tight making the missile turn less. Maybe a 9 G turn at the minute will cause the missile to overshoot?

How much energy loss from a missile doing a turn?

Also does anyone have idea how many Gs a Meteor call pull. It has an outer frame of an AIM-120B, but I the throttle duct can probably support a hard turn.

[deadseal]

Is it better to use 6 G turns to defeat a missile like the AMRAAM or do 9 G turns? Because 9 G turns although the turn is much tighter is depletes energy faster, plus it won't probably cover as much distance singe the turn is so tight making the missile turn less. Maybe a 9 G turn at the minute will cause the missile to overshoot?

How much energy loss from a missile doing a turn?

Also does anyone have idea how many Gs a Meteor call pull. It has an outer frame of an AIM-120B, but I the throttle duct can probably support a hard turn.

good luck trying to spot an AAM to jink against

[eloise]

Those larger bodies you mention also contain heavier avionics, motors, warheads, etc., so more lift is required to get the desired g.

yes iam aware of that but i just feel like the different between lift area is alot more than the different between their weight

Anyway , i made a very rough estimate of wing area on these missile using MK-1 eye ball :
( since missiles fin are perpendicular ,i only included 2 set of fin in total wing area , assumed these other 2 is completely vertical with ground and provide no lift )
For Aim-120 :

So i have decided to measure the wing loading of the AMAARM there may some mistake , but i think it is a decent estimation
AIM-120C have body diameter of 178 mm and total wing span of 445 mm ( 0.445 meters ) http://www.cat-uxo.com/#/aim-120-amraam ... 4588084065
which mean the span of each fin is ( 445-178)/2 = 133.5 mm ( 0.133 meters )
This is AIM-120C fin

here is the fin size relative to the total body

The attachment aim-120c.jpg is no longer available

The photos shows that Aim-120's fin have trapezoid shape ,
For the rear fin : the big base length is around 2.5 times the height
the small base length is around 1.5 times the height
the height (wing span ) as we measured earlier is around 0.133 meters , so the big base is 0.3325 meters , small base is 0.1995 meters
Solve for area :

The attachment aim-120c.jpg is no longer available

we get 0.035 m2 for each rear fin

For the frontal fin : the big base length is around 2 times the height
the small base length is around 0.5 times the height
the height is 0.133 meters so the big base is 0.266 meters , small base is 0.0665 meters
solve for area

The attachment aim-120c.jpg is no longer available

we get 0.022 m2 for each frontal fin

to sum up total fin area for AIM-120 is :
0.035*2 + 0.022*2 = 0.114 m2

For Meteor :

By MK1 eye ball analysis , the air intake of Meteor is short of a rectangle , with height about 60% of Aim-120C rear fin and length around haft of total length of Meteor missiles
so the lift area of each intake is : [ 0.133*60% ] * [3.65* 50% ] = ~0.146 m2
Rear fin of Meteor is bigger than of Aim-120 but the version that F-35 use have clipped fin ,so we can assumed it is similar size with Aim-120 rear fin , area :~ 0.035m2
So total wing area ( intake included ) is : 0.146 + 0.035*2 =~ 0.216 m2 ( since intake in 45 degree with ground and Meteor only have 2 intake , i didnt multiply total area of intake area by 2 )

For R-40

again using MK1 eye ball and some ruler
R-40 rear wing have have trapezoid shape , big base is around 36% missiles total length : 6.22*36% = 2.239 m
small base is around 5.2% of total missiles length : 6.22* 5.2% = 0.323 m
R-40 diameter is 0.31 m , wing span is 1.45m , so the height of each fin is : ( 1.45-0.31 )/2 = 0.57 m
solve for area we have

wing.jpg (22.27 KiB) Viewed 15903 times

area of each rear wing is 0.73 m2
it hard to estimate the size of R-40 frontal fin , but IMHO it reasonable to say they are around the same size as Aim-120 rear fin , so around : 0.035 m2 each
To sum up : total fin area of R-40 is : 0.73*2 + 0.035*2 = 1.53 m2

AIM-120 weight : 152 kg , wing area : 0.114 m2
Meteor weight : 185 kg ,wing area : 0.216 m2
R-40 weight : 461 kg ,wing area : 1.53 m2

So basically R-40 is around 2.5 times heavier than Meteor but it also have 7 times more wing area
R-40 is 3 times heavier than AIM-120 but it also have 13 times more wing area
, of course my calculation are not without errors but i believe that the difference between these missiles is big enough that error of 10-20% isnt going to change things much .

[eloise]

good luck trying to spot an AAM to jink against

spot AAM is probably hard with naked eye , but i think most modern fighter have missile warning system in one form or another
even f-16 have them

[deadseal]

good luck trying to spot an AAM to jink against

spot AAM is probably hard with naked eye , but i nik most modern fighter have missile warning system in one form or another
even f-16 have them

ok
its one thing to know you have been targeted....its another to spot the missile....do you know how fast those things are going, and how small they are?
its hard to see a viper past 1 mile when they are nose on much less a missile that is maybe a foot in diameter.....think realistically. conciously think about sitting in an airplane going 1.1-1.2 mach and have your RWR go off....You start staring in the general vicinity of the spike....think about the relative velocity between you and that AAM missle....now sit there and tell me you think you could spot an AA-10 or 12 covering 1 MILE PER SECOND?? (wikipedia quotes 3000 mph for the missile and call it 1000 MPH for the viper)
ygtbsm

maybe the 35 can track a missile at launch i have no idea. if it could, maybe it could shoot sharks with laser beams on thier foreheads at it

If the missile is big (SA-2) you have a little time from the ability of your eye to see it to TTI

[eloise]

ok
its one thing to know you have been targeted....its another to spot the missile....do you know how fast those things are going, and how small they are?
its hard to see a viper past 1 mile when they are nose on much less a missile that is maybe a foot in diameter.....think realistically. conciously think about sitting in an airplane going 1.1-1.2 mach and have your RWR go off....You start staring in the general vicinity of the spike....think about the relative velocity between you and that AAM missle....now sit there and tell me you think you could spot an AA-10 or 12 covering 1 MILE PER SECOND?? (wikipedia quotes 3000 mph for the missile and call it 1000 MPH for the viper)
ygtbsm

maybe the 35 can track a missile at launch i have no idea. if it could, maybe it could shoot sharks with laser beams on thier foreheads at it

If the missile is big (SA-2) you have a little time from the ability of your eye to see it to TTI

i agree that it very hard to spot missiles by naked eye due to it's speed and size.
But since missiles move really fast, they would be very hot as well, hence easier to detect by IR system. System like DAS, DDM-NG are designed for that job, i dont think it would be far fetched for them to detect a mach 4 missiles from 10-15 km
I mean DAS along with APG-81 can do something like this :
https://youtu.be/qF29GBSpRF4

[eloise]

Aren't the R-33M slightly redesigned with smaller fins though..?
Perhaps lighter seeker warhead etc.

you mean RVV-BD ?

[SpudmanWP]

maybe the 35 can track a missile at launch

Yes it does and it also has the ability to let the pilot know if the missile is headed for him (YATO mode = "You Are The One")

[basher54321]

i agree that it very hard to spot missiles by naked eye due to it's speed and size.
But since missiles move really fast, they would be very hot as well, hence easier to detect by IR system. System like DAS, DDM-NG are designed for that job, i dont think it would be far fetched for them to detect a mach 4 missiles from 10-15 km

As an F-16 pilot DS will no doubt be honoured you agree with him

I think the point being made was that from a pilot point of view the amount of G a modern all aspect missile can pull is largely academic.........but still useful if you want to simulate them obviously.

[deadseal]

maybe the 35 can track a missile at launch

Yes it does and it also has the ability to let the pilot know if the missile is headed for him (YATO mode = "You Are The One")

that is pretty awesome, and could really help with tactics...........

brave sir robin ran away......
bravely ran away away....

and then my wingman killed you in the face!

fist emoji

[eloise]

As an F-16 pilot DS will no doubt be honoured you agree with him

I think modern jet are equipped with much better sensor to detect AAM compared to F-16 that DS fly (i would guess block 50-52 )

I think the point being made was that from a pilot point of view the amount of G a modern all aspect missile can pull is largely academic.........but still useful if you want to simulate them obviously.

i disagree with this , dodge something like Aim-9X is obviously harder than a Aim-7 , even though they are both all aspect

[basher54321]

I think modern jet are equipped with much better sensor to detect AAM compared to F-16 that DS fly (i would guess block 50-52 )

Some could be - you have listed two known systems that can potentially track AA missiles - however I wasn't aware this discussion has been limited to the very few modern aircraft with such systems and DS brought up an crucial point that certainly looked like was not even being considered.

i disagree with this , dodge something like Aim-9X is obviously harder than a Aim-7 , even though they are both all aspect

Clearly but not actually what I was getting at - your example is proof of that - don't get hung up on a single variable.

[eloise]

eloise,
You maybe surprised at the amount of body lift from a simple tube. Go back and look at the charts you posted Oct 22 as Figure 9, Normal Force Coefficients, CN. CN is very similar to lift coefficient, just a slightly different reference system. There are three charts on the right side, body CN, body+tail CN, and tail+carry-over CN. Carry-over is a small effect of the tail on body CN. Each chart shows the CN for three different angles of attack, 4, 12, and 20 deg at a range of mach number from 1 to 4. Let's look at CN for 12 deg AoA, mach 3. For body only, CN = 1.3. For body+tail, CN = 2.0. For tail+carry-over, CN = 0.7. So body lift is (1.3/2.0) of the total lift or 65%. The tail fins contribute only 35% of total lift.

So even though a simple tube is a relatively poor lifting surface, it has so much area it provides almost twice the lift as the tail fins.

The chart on the left shows the location of the center of lift of each component along the length of the missile, expressed as missile diameters aft of the nose. At our example 12 deg AOA, mach 3, body lift is at 5d, body+tail at 6.8d, and tail+carry over at 10.8d.

missile lift.jpg

johnwill what do you think about this chart ?

why is that CL go opposite to CN coefficient at a certain point ?
is maximum value for CL caped at 1 ?
what is the likely CL value for aim-120 fin at mach 4 ?