You are graded on your performance after every mission; C, B, A or S, with S being the highest rank. The requirements vary between missions and most are based on time, score or a combination of both. It seems as though some missions (escort, defend) depend on how much damage your allies take (missions 9, 15)

Getting an S-rank on every mission earns you a medal.

'?' means that we know the requirement (time, score or both) but not what it is.

'??' means that the requirement is currently an unconfirmed guess based on what you need for an A-Rank

Mission 1:
Time: Under 2:00

Mission 2:
Time: Under 3:30

Mission 3:
Score: 6500 (??)

Mission 4:
Time: 1:30

Mission 5:
Time: 2:00

Mission 6:
Time: Under 3:30 (??) 3:16 Got me an S.

Mission 7:
Time: 3:20

Mission 8:
Time: 1:50 (??)
1:52 yields an A Rank.

Mission 9:
Time: Under 3:00 minutes (??)

It is possible that the S-Rank on this mission is dependent on the amount of damage that the city sustains (the 4 blue circles), try to take out the bombers as quickly as possible and focus on the ones nearest to the blue circles.

Mission 10:
Time: 2:00 (??)

Mission 11:
Time: 4:00 (??)
(Got an A with a time of 4:20 and an S with 3:07)

Mission 12:
Time: 5:30 - 4:10 (?)
(5:32 = A, 4:06 = S)

Mission 13:
Time: 2:00

Mission 14:
Time: 4:00
(4:56 = A, 3:27 = S)

Mission 15:
This mission appears the S-Rank on this level is contingent on all 3 allied ships making safely across the return line.

Mission 16:
Time: 5:00 (4:49 = S, 5:04 = A)

Mission 17:
Time: 5:00 (??)

Mission 18:
Score: 7000 - Take out all of the required targets as well as the enemy Ace and as many RPGs and Stingers as possible.

Mission 19:
Time: 2:00

Mission 20 :
Score: 18500 (??) **You must kill everything in the mission for the S, so make sure you take out the Guns and SAMs before destroying the boats.

Destroy the 4 aircraft at the beginning (2x F14 + 2x Rafale M) and then destroy the first wave of enemy ships. When the second wave appears, destroy all of the target ships, if you have completed this in under 2 minutes, the enemy Ace will appear (Superfly F35), kill him. Destroy any remaining Gunships and the first XB-10. The next two XB-10s will appear, destroy their escort fighters (2x MiG 1.44) and then the air support fighters that show up after (should be 4 Su37s). Now take out those two XB-10s. All that's left will be the 4 Ace fighters that appear after the cut-scene, take them out and you should have your S-rank.

Mission 21:
Points: 9000

Mission 22:
Time: 0:45
(Got an A with 0:46 and an S with 0:44)

Mission 23
Time: Under 3:30 I think.
3:23 gave me an S.

F-4E Phatom II

F/A-18E Super Hornet

F-15S/MTD

F-15SE Silent Eagle

X-29A

F-14D

A-10A Thunderbolt II

YF-23A Black Widow II

F-16C Fighting Falcon

F-117A Nighthawk

F-22 Raptor

F-35 Lightning II

Typhoon

Mirage 2000D

Rafale M

JAS-39 Gripen NG

MiG-21-93

MiG-31 Foxhound

MiG-1.44

SU-25

SU-37 Terminator

SU-47 Berkut

PAK FA

F-2A

XFA-27

ADF-01 FALKEN

A6M5 Type Zero Carrier Fighter

F6F-5 Hellcat

Les ACES, il permettent de débloquer aussi bien des équipements que de nouveaux avions.

1
MiG-21
Goldwing
Appears with last wave of fighters if you arrive under a minute.

2
B2-A
Cosmic
The target transport near the end of the mission (but before the Lancer Squadron will appear) will move towards the center of the map if you let it be. The B2-A is located in the mountain ravine directly underneath where the transport will stop at

3
Vehicle
Big Cat
When you arrive to the bay of the city (after passing the bridge) you will need to destroy the 2 F-4E planes in the aircraft carrier, and the first wave of F-4E flying over the area. The Big Cat will appear at the start of the bridge moving along until it arrives to the tunnel and dissapears.

4
Su-37
Ricochet
Appears to the northeast of the second target at the mission start. Flies around for a while before leaving back east off the map

5
F-117A
D. Cowboys
Near upper targets at beginning(Near to the cluster of fuel tanks)

6
PAK FA
D.R. 2000
During Beast Squadron phase

7
F-4E
Razorback
Left E-747 cluster

8
MiG-31
Dao
Escort fighters

9
Boat
Leonid
Landing boat in the water with the third wave

10
Typhoon
Hangman
Destroy all ground enemies

11
F-14D
Tallman
With F-14 squadron, one of the 4 F-14 after the first AV-8 appears

12
Rafale M
Rosepink
Appears with Cocoon, 1st part of mission(May need to shoot down Cocoon squadron to appear)

13
CH-47
Comet
CH-47 under a bridge; follow the Apache path

14
Gripen NG
Jian
Appears while saving the commander(appears as a lone aircraft on map)

15
X-29
Xiao
Along the white line along the left side

16
F-16
Metal Sphere
Right before the doors open

17
F-15
Stalker
Appears with Beast Squadron

18
SU-25
Meteor
Group of SU-25 Frogfoot

19
YF-23A
Max&Goose
Appears with enemy reenforcements

20
F-35
Superfly
Destroy all the TGT ships before the XB-10s and Superfly will appear

21
Tank
Mole
Tank appears after SAMs under the archway

22
AH-64
Hot Snow
Lower left corner after missile launch

23
Su-47
F.F.F.
During power plant phase, flying around by itself

Ma source, plus complete:

rank-S :
http://www.gamefaqs.com/3ds/609543-ace-combat-assault-horizon-legacy/wiki/3-1-s-rank-requirements

Tableaux des ACES et ce qu'ils débloquent:
http://www.gamefaqs.com/3ds/609543-ace-combat-assault-horizon-legacy/wiki/3-2-list-of-ace-pilot-locations

Avions et armes:
http://www.gamefaqs.com/3ds/609543-ace-combat-assault-horizon-legacy/wiki/3-3-list-of-available-aircraft-and-weapons

merci pour tes astuce et bon vol !

Sympa le C/C, pas de recherche de traduction, c'est dommage!

MERCI