The AIM-120 'AMRAAM' - History, Design, Performance & Discussion

I remember reading “enhanced kinematics” regarding the AIM-120C-5, likely the extended tail section restores some of the maneuverability lost from the AIM-120C-3 variant (if any) or is referring to improved performance when lofting due to the longer propulsion unit. Regardless, I do not think the clipped wings has any significant bearing on maneuverability… nor was I referring to the tail section as to infer it was not also clipped. The tail control design benefits greatly from the AMRAAM type missile layout.

AIM-120C (variant unnamed) has high-off bore capability, showing the improved weight balancing mentioned before and it’s enhanced maneuvering characteristics.

https://cdn.discordapp.com/attachments/955829235493273680/1122659545601282058/image.png

So they reimplemented the English bias system of the Sparrow?

“High-angle” off-boresight is not necessary for simple English bias at BVR. Usually this is only referred to in the sense that the missile is being used within active range. This is a capability only possible through an increase in the level of instability of the missile when motor propellant is full, owing to a bias in weight towards the rear that was capitalized on and possible due to lighter weight electronics… and later in the AIM-120C-5 a move towards a shortened control actuator section (SCAS) and longer rocket motor.

Comparing the DCS AIM-120 to the real thing based on confirmed sources;
AIM-120B

Spoiler

Weight [4]
DCS - 157.85kg
IRL - 147.87kg

G-Limit [Korean Source]
DCS - 30
IRL - 35

Booster Burn Time (Korean source says total is 6-8s burn)
DCS - 2.1s
IRL - 1-2s

Sustainer Burn Time (Possibly accurate?)
DCS - 5s
IRL - ~5-6s

Fuel mass (Correct! Hurray!)
DCS - 46.54kg
IRL - 46.54kg

It seems to me that the DCS missiles accuracy is based on outdated information, at the time it was made they had the best available information… I hope when the AIM-120 comes to war thunder we have a more realistic example of the missile than what can be found in DCS and so that’s what I’m striving for here. (Without the use of restricted sources).

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Their drag CFD is really cool though, great post!

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I have found a document that I think is very obviously detailing the AIM-120, testing was done in 1985 and the missile was simply referred to as “tail controlled missile”. In this document, it clearly states the missile was able to be rolled, roll stabilized, and maneuvered in combined plane on command.

https://cdn.discordapp.com/attachments/955829235493273680/1123371774084661358/image.png

This is the figures showing the missile design;
https://cdn.discordapp.com/attachments/1078877088087552102/1123373326476267530/image.png
https://cdn.discordapp.com/attachments/1078877088087552102/1123373739283861594/image.png

@tripod2008 @Fireball_2020 I think this definitively proves the AIM-120 should maneuver in combined-plane in war thunder. It also mentions instability and goes over how to control unstable missiles. All features of the AIM-120, at some point.

Proof of availability for public distribution
Here is the full document, starting on page 260

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I just wouldn’t be absolutely sure that it wasn’t for the RIM-7PTC (eventually became the RIM-162) as that also involved implementing Tail control to a similar missile and with the Fold out fins they may well look similar.

Regardless, the AIM-120 should be at least 35G, I think it is the single-plane maneuverability of the AIM-120B/C.

According to designer of PL-12, the AIM-120C is a 50G missile (presumably combined plane) which would be 35G single. This also agrees with the Korean source for the AIM-120B (Which itself references the F-16 manual).

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I remember you went for 28G in the old forum for both models (120A and 120C-3

I could see A/B being 35G’s and B/D being 28G’s. Both still more manoeuvrable than sparrow.

New documentation says otherwise, I’m not one to dismiss better sources for data. The 28G maneuver comes from a source that simply stated it pulled 28G to intercept. In no place did it ever claim the maximum overload was 28G.

Seeing as it gets more maneuverable over time, I don’t think this is the case. It says in these sources the AIM-120B is 35G and the Chinese source says AIM-120C is 50G (combined).

I have updated the original post now that I’m able to edit it again.

Also it seems I was right and they capitalized on the AIM-120C-5’s increased motor length to reduce missile stability and allow “over-the-shoulder” launch capability of the AIM-120 in 2002. They did this through a simple software update. @Fireball_2020 @tripod2008

Some interesting photos from the Smithsonian

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Is that a s225x?

Spoiler

images-40

No, it’s the Raytheon AMRAAM which competed against the Hughes model. Later Raytheon bought Hughes in the mid to late 90s and continued the legacy of the AMRAAM.

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To be fair, 28G is just the floor it seems. In the source, it states that it pulled 28G in order to hit a target. The situation might not have required more than 28G, so the missile did just enough G’s to hit the target.

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https://media.discordapp.net/attachments/1078877088087552102/1128760347193528421/Hughes_1.png?width=1366&height=889
https://media.discordapp.net/attachments/1078877088087552102/1128760347680063709/Hughes_2.png?width=1267&height=889

All early Hughes documentation labels the missile as 326 lb “tactical weight”. Other sources also quote this and later models such as AIM-120C as 335 pounds, or even more in the case of much newer versions.

The maximum overload of AIM-120B is confirmed around 35G due to the Korean Study referencing TO-34-16C (with permissions).

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Northrop and Motorola also teamed up and came out with advertisements of a similar design to Raytheons.
https://cdn.discordapp.com/attachments/955829235493273680/1136495240140820540/HRy17v9.png
https://cdn.discordapp.com/attachments/955829235493273680/1136495481393008811/QQaUuEz.png

You’ll hear it here first, but the AIM-260 takes more after these “body-lift, tail-control” designs than it does the AMRAAM we all know and love today. A “high performance wingless missile” of sorts.

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Speaking of motorola and AMRAAM, they are a subcontractor making a number of parts for the AMRAAM to this day as far as I am aware.
http://blog.planet4589.org/space/archive/MartinPfeiffer/SandiaNews84-97/C1055_Lab_News_10-04-91.pdf

https://cdn.discordapp.com/attachments/955829235493273680/1136499170878955541/image.png

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