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AIM-54 Phoenix performance


Pilum
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Open sources indicate that the Phoenix has a range in "excess of 100 Nm" which is quite extreme and one can wonder in what type of scenario this would be possible?

 

I have over the years developed a C++ program that can calculate missile kinematics and lately I have fiddled around a bit with a AIM-54A model testing out different launch speeds, loft angles, missile aoa during flight, target speed etc and come up with the attached scenario which indicates that it is at least quite possible from a missile kinematics perspective:

 

The scenario in the attached figures is a head to head engagement with a target doing M=0.67 at 10 Km which AFAIK is the cruise speed of the Tu-95 Bear and the F-14 doing M=1.4 with a launch distance of a little over 190 Km, i.e. "in excess of 100 Nm". One figure is true to scale and the other scaled up to improve reading of flight data.

 

I have simply reverse engineered this so I have no idea if this is close to the IRL launch profile used to attain the range "in excess of 100 Nm" but the simulation certainly shows that it is within reason and in addition, my simulations indicate that with an even higher loft angle and higher launch speed the missile intercept can be moved out even further.

 

So, does anyone have more info or input that could help improve the simulation and shed some light on really long range missile intercepts? I have used open sources to come up with the following missile data for the AIM-54A:

 

Missile drag: Lacking solid data here this is tricky and since it is short stubby missile it is difficult to come up with a good estimate based on comparisons with other more slicker missiles. So with no solid data to go on I have assumed a drag area (Cdo x reference area) varying between 0.04-0.11 m**2 depending on missile Mach.

 

Impulse: 492480 Ns burntime 27 s. Have no idea if the Phoenix has a boost and sustain phase or if it is a continuos burn so for the time being thrust is assumed constant at around Impulse/burntime = 18000 N. Impulse calculated as the product of fuel weight and an assumed 240 s specific impulse. Burntime pulled out of a figure on the internet, no idea if that is correct. However, the data on the fuel weight seems more solid: AIM-54A fuel weight 200.8 Kg generously provided through open source US defence document "Hazard Classification of US Military Explosives and Munitions" rev 14, June 2009." :music_whistling:

 

Simulated loft angle and launch speed: Pure guesses, but open sources indicate that the missile peaks out between 80 and 100,000 ft so I think I'm in the right ballpark with my 91,000 ft.

 

I think getting this as close to IRL performance as possible in DCS would be nice and since the Leatherneck developers actively participate in forum discussions I thought some input to the Phoenix modeling may not hurt.

 

So any constructive input to improve the C++ simulation and/or understanding of long range Phoenix shots would be welcome: Are any of the assumptions unreasonable and is there more data out there that could be used to improve the simulation and modeling in DCS?

AIM54A1488kmhloft.bmp

AIM54A1488kmhloftscaled.bmp

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Pilum aka Holtzauge

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Interesting. The most important detail I see in there is that the actual range (relative to ground) is about 160km with a speed still over mach 1. Maybe it's just me, but that's the only distance I actually care about and it seems to be a shockingly difficult range to find in original source material. They always list engagement profiles but never seem to give a pure range with x velocity at y altitude chart.

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A very interesting piece of work mate! :thumbup:

I hope the missile experts will chime in and add to it with their inputs :)

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Interesting. The most important detail I see in there is that the actual range (relative to ground) is about 160km with a speed still over mach 1. Maybe it's just me, but that's the only distance I actually care about and it seems to be a shockingly difficult range to find in original source material. They always list engagement profiles but never seem to give a pure range with x velocity at y altitude chart.

 

Yep, in order to get a 100 Nm plus range you need a really co-operating target going in a nice straight line. Any manovering on the part of the target will ruin your day.

 

 

A very interesting piece of work mate! :thumbup:

I hope the missile experts will chime in and add to it with their inputs :)

 

Tnx! and yes, it would be good to get a discussion going because while I think the actual flight model is OK there is a good amount of guesswork when it comes to the input such as launch speed, loft angle, missile drag etc so it would be good to narrow this down a bit.

 

Old Crow ECM motto: Those who talk don't know and those who know don't talk........

 

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Pilum aka Holtzauge

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Thrust is 4000lbs for 30sec.

According to parts availability, the same rocket mirror was used for all versions of the missile.

 

Longest known shot recorded vs done is 142nm, parameters unknown ... But I very highly doubt that anyone was subsonic in that case.

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Thrust is 4000lbs for 30sec.

According to parts availability, the same rocket mirror was used for all versions of the missile.

 

Longest known shot recorded vs done is 142nm, parameters unknown ... But I very highly doubt that anyone was subsonic in that case.

Probably not..... also it must have been at very high altitude

Modules: FC3, Mirage 2000C, Harrier AV-8B NA, F-5, AJS-37 Viggen, F-14B, F-14A, Combined Arms, F/A-18C, F-16C, MiG-19P, F-86, MiG-15, FW-190A, Spitfire Mk IX, UH-1 Huey, Su-25, P-51PD, Caucasus map, Nevada map, Persian Gulf map, Marianas map, Syria Map, Super Carrier!

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Thrust is 4000lbs for 30sec.

According to parts availability, the same rocket mirror was used for all versions of the missile.

 

Longest known shot recorded vs done is 142nm, parameters unknown ... But I very highly doubt that anyone was subsonic in that case.

 

Motor? There were two types of motors used for the AIM-54A and the AIM-54C is quoted to have "improvements in the rocket motor that increase range and speed." That leads me to believe a new solid fuel rocket.

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Maintenance manuals claim same propulsion unit.

The diameters and weight are most likely similar and there are interchangeable motors. I still haven't found a single RIO that will own up to their longest range shot with the C, but from what I've read, C, C+, C(ECCM sealed), C (high power) all have about another Mach level capable and longer range. The C(highpower) uses the same TWT as AMRAAM and may give the DSQ-26 a boost in detection range-may go active sooner, or just be more resistant to jamming.

 

I haven't read a single manual on the AIM-54, everything I've read is from public knowledge, so I don't know what you're reading, it may be more reliable.

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The maintenance manual very clearly says, "This propulsion unit is used by all AIM-54 models".

 

It doesn't say WPU-this for one missiles and WPU-that for another, like it does for different models of Sparrow or AMRAAM or Sidewinder, for example.

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The maintenance manual very clearly says, "This propulsion unit is used by all AIM-54 models".

 

It doesn't say WPU-this for one missiles and WPU-that for another, like it does for different models of Sparrow or AMRAAM or Sidewinder, for example.

 

So check the date on your manual, it may be after the C version was the only unit in production, and the new motor was retrofitted to the older A models or could be. Every reference to the C I've read describes motor improvements with more speed and longer range, in addition to the solid state avionics, and internal cooling.

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Hercules/Rocketdyne Mk 47 (Mod 1?), using Flexadyne (PBAN) propellant (impulse ~252 s)

Aerojet Mk 60, using ammonium perchlorate-polyurethane rubber binder propellant (impulse ~252 s)

 

**EDITED** Apparently the MK60 is not a new motor but was an equivalent, produced until 1978....the Mk47 Mod 1 was produced until 1992(last AIM-54 motor delivery)

So you've most likely got data on the MK 47. I learned a little something tonight. It's possible the AIM-54C had better loft and guidance characteristics, and maybe that allowed for a possible longer range and speed.

 

Sorry for the confusion, up until now, I was convinced the C had a newer motor.

 

http://www.designation-systems.net/dusrm/m-54.html There's a table with data listing the AIM-54C as a faster and higher flying missile, that's gotta be it.


Edited by turkeydriver

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Even if this is the case, data is available only for one rocket motor AFAIK.

 

Yes that seems correct, Having the Maintenance manual would end the rocket motor discussion,

 

However Janes Defence 1988 lists 2 rocket motors that were used:

 

Propulsion Rocketdyne MK 47 or Aerojet MK 60 single-stage solid-fueled rocket motor

 

However it does not state which production versions of the 54 had which rocket motors.

 

Of Notable interest, refer Figure D page 6

 

http://enu.kz/repository/2011/AIAA-2011-6941.pdf

 

Sources:

 

http://www.secretprojects.co.uk/forum/index.php?topic=15336.0

 

http://www.designation-systems.net/dusrm/m-54.html

 

http://www.aviatia.net/armament/aam-missiles-air-to-air/aim-54-phoenix/

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It's pretty much like the alternate motors for the AIM-7 - each version had equivalent motors built by two manufacturers.

 

They did the same thing, but they came from different suppliers. One of the reasons for this is to diminish parts scarcity, and also to get better economy.

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Thrust is 4000lbs for 30sec.

According to parts availability, the same rocket mirror was used for all versions of the missile.

 

Longest known shot recorded vs done is 142nm, parameters unknown ... But I very highly doubt that anyone was subsonic in that case.

 

Ok, that is interesting info. Do you have a source for that because it would be good to understand the background since reverse engineering those figures and assuming a specific impulse of 252 s (I = 4000 lb x 30 s= 120000 lbs and 120000/252 = 476 lb fuel or 218 Kg) this would lead to a motor weight which is not too far from the one I have assume for the AIM-54A which was 200.8 Kg.

 

 

Also, 142 Nm seems really long and would most likely involve both a supersonic launch and target. In addition, the target would have to have a pretty big RCS to be able to get a lock-on at +260 Km :)

 

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Pilum aka Holtzauge

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For that sort of test I suspect they'd have used an RCS enhancer.

 

In any case, regarding the source, it may or may not be accurate - it's from a collection of details about various weapons. It is official, but there have been typos in it ... and I currently do not have it handy.

 

Also, impulse (and thrust) is an ok benchmark, but only accurate for one pressure altitude. To top that all off, thrust will be maximized at altitude the rocket is designed for, and thrust generally tends to increase at higher altitudes.

 

So it may all be 'the same', but one's talking about thrust at SL and the other, higher (but that's a bit hard to believe :) )


Edited by GGTharos

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Thanks all for the input and links, lots of good reading and interesting info there!

 

Some more thoughts beginning with the AIM-7F Sparrow: From the SMC for the Sparrow AIM-7F dated January 1977 we have the propellant weights 52 lb for boost and 82 lb sustain, i.e. 135 lb total or 61.3Kg.

 

This tabs well with the figure of 132.901 lb "NEWQDLB" weight in the Hazard document:

 

HAZARD CLASSIFICATION OF UNITED STATES MILITARY EXPLOSIVES AND MUNITIONS U.S. ARMY DEFENSE AMMUNITION CENTER, REVISION 15, JUNE 2012

 

VG26 RCKT MTR ASSY, MK58-7 AIM-7 SPARROW (37) 1.3C 0186 7 132.901 60.2827

 

More from Hazard document:

 

“C. The NEWQDLB is sometimes less than the total explosive content of theitem because testing has shown that all the explosive does not contribute to quantity distance computations. Such items are identified by NOTE 4 in the "NOTES" column.”

 

Since there is no “Note 4” for either the Sparrow or Phoenix rocket motor assembly this would imply that the Hazard doc really lists the actual propellant weight contained and not some explosive equivalent.

 

AIM-54 has two entries for rocket motor:

 

V877 PROP SECT, MXU-637/B, F/AIM-54A PHOENIX 1.3C 0186 7 459.000 208.199

V885 PROP SECT, MXU-637A/B F/AIM-54C PHOENIX 1.3C 0186 C 360.000 163.293

 

So this would imply that the C model only has 163.3 Kg propellant while the A has 200.2 Kg which seems a bit strange seeing the C is claimed to have better range than the A……

 

In addition, the AIAA 2011-6941 document Winfield_Gold linked above, shows a Mk 47 motor assembly that is supposed to be 15” by 70”. However, since 15” is the diameter of the missile itself and figure 5 in that document shows that there are lugs sticking out the actual diameter of the propellant must be less than that. Eugene Fleeman’s book Tactical Missile Design gives the density of 252 s solid fuel at 0.062 lb/in**3 or 1718 Kg/m**3 so a ballpark calculation assuming the propellant part of the motor is 40” of the total 70” length with a diameter of 14” would be in the order of 168 Kg which tabs pretty well with the 163.3 Kg in the Hazard document.

 

However, I would have thought that the upgrade to modern electronics from AIM-54A to C model would have freed up some space for more propellant not less? OTOH, that upgrade purportedly introduced better ECCM, improved guidance and control section, strap down inertial guidance etc so maybe this took up more space than before?

 

In addition: About the interchangeability of the rocket assemblies, note that the A version motor has the designation MXU-637/B while the C version has the designation MXU-637/A/B so maybe the B here indicates that it can be fitted to the AIM-54A as well which would explain why the maintenance manual say they have the same motor?

 

However, I don't get why the AIM-54C model would have only 79% of the fuel weight of the A and still have same or better range given that the C is even heavier?

 

 

So as they say, still confused but on a higher level…..

 

Old Crow ECM motto: Those who talk don't know and those who know don't talk........

 

http://www.crows.org/about/mission-a-history.html

 

Pilum aka Holtzauge

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For that sort of test I suspect they'd have used an RCS enhancer.

 

In any case, regarding the source, it may or may not be accurate - it's from a collection of details about various weapons. It is official, but there have been typos in it ... and I currently do not have it handy.

 

Also, impulse (and thrust) is an ok benchmark, but only accurate for one pressure altitude. To top that all off, thrust will be maximized at altitude the rocket is designed for, and thrust generally tends to increase at higher altitudes.

 

So it may all be 'the same', but one's talking about thrust at SL and the other, higher (but that's a bit hard to believe :) )

 

Yeah, I'm with you about the impulse only being valid at one altitude but I have assumed SL for all my data and I compensate for altitude so at 10 Km it will be more than the numbers we are talking about here and I assume the 252 s figure for the specific impulse is SL.

 

Old Crow ECM motto: Those who talk don't know and those who know don't talk........

 

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The A/B seems to be listed for the 54C only, the /B for 54A and 54C. They are listed under Mk47 'Intert' motor.

 

Both Mk47 and Mk60 motors are listed as part MXU-637/B

 

PDF's page 131.

 

http://www.readbag.com/usa-federal-forms-navy-3-pdf-forms-pubs-neds-daps-dla-mil-directives-08000-ordnance-material-management-and-support-08-00-general-ordnance-material-support-8000-16b-7

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In addition: About the interchangeability of the rocket assemblies, note that the A version motor has the designation MXU-637/B while the C version has the designation MXU-637/A/B so maybe the B here indicates that it can be fitted to the AIM-54A as well which would explain why the maintenance manual say they have the same motor?

 

However, I don't get why the AIM-54C model would have only 79% of the fuel weight of the A and still have same or better range given that the C is even heavier?

 

The "/B" means that the particular component is expendable. The "A" means it's the first revision (i.e. it's the second version).

 

Don't forget that rocket propellants are not necessarily solid cylindrical masses. They can be hollow, and or contoured to adjust the thrust profile. It's possible that a careful redesign of the shape could obtain the same or greater range with less propellant.

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Don't forget that rocket propellants are not necessarily solid cylindrical masses. They can be hollow, and or contoured to adjust the thrust profile. It's possible that a careful redesign of the shape could obtain the same or greater range with less propellant.

 

Yes for sure the cross section can vary and the calculation I did earlier was just a ballpark estimate but the point was that I was calculating it as solid but that still did not amount to more than 168 Kg and therefore not close to the 200.8 Kg stated for the A model.

 

Secondly, while you can to some extent tailor the thrust due to the area burning, you can't change the specific impulse and it seems the Phoenix was in the order of 252 s which is close to really high smoke propellants that AFAIK top out at 265 s. I find it hard to believe that the C model had a 459/360 higher specific impulse, i.e 321 s to compensate for the lower fuel weight.

 

Old Crow ECM motto: Those who talk don't know and those who know don't talk........

 

http://www.crows.org/about/mission-a-history.html

 

Pilum aka Holtzauge

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The A/B seems to be listed for the 54C only, the /B for 54A and 54C. They are listed under Mk47 'Intert' motor.

 

Both Mk47 and Mk60 motors are listed as part MXU-637/B

 

PDF's page 131.

 

http://www.readbag.com/usa-federal-forms-navy-3-pdf-forms-pubs-neds-daps-dla-mil-directives-08000-ordnance-material-management-and-support-08-00-general-ordnance-material-support-8000-16b-7

 

Ok, but it stills seems strange with the lower fuel weight 360 lb for the C when the A is listed as 459 lb......

 

Old Crow ECM motto: Those who talk don't know and those who know don't talk........

 

http://www.crows.org/about/mission-a-history.html

 

Pilum aka Holtzauge

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Hang-on: I just noticed that the the AIAA 2011-6941 document Winfield_Gold linked earlier states “364 lb Flexadyne propellant” for the Mk47 rocket motor so this also tabs well with the 360 lb in the Hazard doc. This would then indicate that the impulse for the AIM-54C would be in the order of 364 x 252 = 91728 lbs, i.e. in the order of 83% of what I assumed (110577 lbs) in the AIM-54A simulation in post #1.


Edited by Pilum

 

Old Crow ECM motto: Those who talk don't know and those who know don't talk........

 

http://www.crows.org/about/mission-a-history.html

 

Pilum aka Holtzauge

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