Bf 109K-4

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World War II aircraft
Bf 109K-4
Bf 109K-4
Variant of Bf 109
Nickname Kurfürst
Type Fighter/attacker
Country of origin Germany
Manufacturer Messerschmitt AG
Crew Single-Seat
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The Bf 109K-4 in World War II


The Bf 109 Kurfürst series was the evolution of the Bf 109G-10.The K series was a response to the fact that the bewildering array of series, models, modification kits and factory conversions for the various Bf 109G versions led to logistic problems, making production and maintenance complicated and costly - something Germany could ill-afford late in the war. As such, the RLM (German Aviation Ministry) ordered Messerschmitt to rationalise production of the Bf 109, consolidating parts, types etc to produce a uniform, standard model with better interchangeability of parts and equipment.

the standardization included:

- aerodynamic improvements, the bulges on the cowling disappeared

- improved landing gear with bigger wheels

- fully retractable, longer tail-wheel for better airflow in T/O and better sight when taxiing

- new tail unit with rudder trim tabs

- improved DB 605 engine

- blind flying instruments

- stronger armament

- "Erla Haube" canopy for better vision

Unit Deployment


  • K-0 Pre-production aircraft, powered by a DB 605DM engine
  • K-2 proposed version without pressurized cockpit
  • K-4 only serial production version without pressurized cockpit, powered by a DB 605DM, DB or DC engine
  • K-6 proposed heavy fighter version, as K-4 with reinforced wings holding two additional 30 mm MK 108 cannons and additional armour
  • K-8 proposed reconnaissance version, equipment similar to G-8
  • K-10 proposed version, similar to K-6, MK 103mot engine cannon instead of MK 108
  • K-12 proposed version, dual-seat trainer similar to G-12
  • K-14 proposed version, similar to K-6, powered by a DB 605L engine


Bf 109 was the official Reichsluftfahrtministerium (German Aviation Ministry, RLM) designation, since the design was submitted by the Bayerische Flugzeugwerke company, and was used exclusively in all official German documents dealing with this aircraft family. The company was renamed Messerschmitt AG after July 1938 when Erhard Milch finally allowed Willy Messerschmitt to acquire the company; from that date forward, all Messerschmitt aircraft were to carry the "Me" designation except those already assigned a Bf prefix. Wartime documents from Messerschmitt AG, RLM, and others continued to use both designations, sometimes even on the same page, but there were several RLM orders to deny acceptance of documents carrying the Me prefix for the Bf 109. Me 109 is known to have been the name used in print by Luftwaffe propaganda publications as well as by the Messerschmitt company itself after July 1938, and Luftwaffe personnel, who pronounced it may hundert-neun. The Me 109 ("emm ee one-oh-nine") designation was usually used in the English-speaking world. However, in both wartime and contemporary literature, both the "Bf" and "Me" as well as "ME" prefixes are used. All extant airframes are described as "Bf 109" on identification plates, including the final K-4 models.

Origins Of 109's Names

The nicknaming of the 109s Anton Emil Freidrich Gustav Kurfurst etc is based on the German phonetic alphabet of the day relating to the model letter of the aircraft: Anton, Berta, Caesar, Dora, Emil, Friedrich, Gustav, Heinrich, Ida, Josef ,Kurfurst, Ludwig, Martha, Nordpol, Otto, Paula, Quelle, Richard, Siegfried, Toni, Ulrich, Viktor, Wilhelm, Xantippe, Ypern, Zeppelin.

External Links

Luftwaffe and Bf109 cockpit resource(German)

Hans-Joachim Marseille by Major Robert Tate, USAF

An excellent read, interview of Erich Hartmann

Possibly spurious yet highly captivating account of an American pilot's encounter with a German fighter ace beleived to be Hartmann

Flight report on a restored BF109 g10 (basically a k4)Black 2

Photo gallery of restored BF109 g10 Black 2

Aces High II aircraft
Bf 109K-4
Bf 109K-4
Variant of Bf 109
Type Fighter/attacker
Crew 1
Index 2
Aces High II loadout options
Package 1 1) 30 mm MK 108 65 rpg
2) 13 mm MG 131 300 rpg
Options 300 Litre Drop tank
Aces High II Main Arenas
Earliest MA Late War
Typical perk cost 0 (Late War)
ENY value 20 (Late War)
Available on carrier no
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The Bf 109K-4 in Aces High II

Engine Power

The Bf109K-4 is an absolute monster of engine performance at low through high altitudes. Sea-level speed is very good, 339mph, 368mph with WEP. Speed climbs quickly through 5K (368/398), then a little more gradually through 10K (383/412), 15K (398/428), 20K (413/446) and 25K (431/445). Performance degrades above 26K, note the drop in top speed between 20 and 25K with WEP, albeit slowly. That makes the K4 a 400mph fighter at only just over 5K (at light weight and clean). The K-4 is likely in the top couple of rides for speed at altitudes up to 20K or so. Climb rate is equally impressive, around 4,500ft/min at sea-level, improving a bit to 4,700ft/min at 5K, but then slowly decreasing such that at 17K you still have 4,000ft/min with WEP. That’s excellent and again in the top handful of AH performers. Acceleration matches the climb, it’s unbelievable and a huge asset. If you aren’t excessive about WEP use you should always have plenty, but be careful about leaving it on for extended periods none the less.

Fuel duration is not very good with only 106 gallons internally, which tends to last only about 27min at military power, enough for a reasonable climb, transit and fight, but with WEP use that total will drop to more like 21 minutes. A centerline drop tank option adds another 79 gallons and is quite commonly carried (adding ~20 mins more flight time). There is a drag penalty though, even after the drop tank is discarded, but it tends to be minor.

Aces High II Performance Charts

109k4spd.jpg 109k4clmb.jpg



The 109K4 carries a devastating 30mm Mk 108 cannon (65 rounds) mounted to fire through the propeller spinner. A pair of cowl mounted 13mm Mk 131 guns (300rpg) add a decent secondary hitting power. I’m not a fan of 30mm cannons for use against fighters, it tends to fire too slowly, the ballistics are marginal, and the damage it inflicts is overkill. With practice (lots) a person can get used to it but it’s typically too much of a handicap for new players. It is also something hard to adjust to if you’ve been flying something with good ballistics, like .50cals or hispanos, and thus switching in/out of a 30mm is always a challenge. I’ve set the 30mm convergence short, around D250, because outside of this it’s almost impossible to hit a maneuvering target. I know some people set it to max range to put some extra loft into the trajectory. Most players underestimate the drop on the rounds so the extra loft might help but still limits the effective range to something around D250 for most players. The 13mm you can set to whatever you desire, they fire almost parallel anyway so if you set them longer it will give some reach (D400+). Total firing time for the 30mm is only 7 seconds, but the reality is you should only fire 1-2 rounds at a time and then re-aim. The 13mm give ~22 seconds, enough that you can fire them around a bit to scare people and make them turn, giving you a larger target to aim at. The only external option is the 300L drop tank, there are no bombs, rockets or gun-pods.


The 109 series evolved from weights in the 5,500lb class through the K-4 which can tip the scales over 8,100lbs. The wing-loading increase wasn’t kind to the 109K-4 and I generally don’t feel it handles that well. It isn’t a strong aircraft in terms of maneuverability, especially at high weights and high/low speeds. Turn-radius is not good, nor is turn-rate, but the engine does have enough power to drag the K-4 around. Part of the issue is that the K-4 is a very hands-on aircraft, with a lot of throttle and rudder work required vs. many other aircraft that are more point-and-shoot. The K-4 is very speed sensitive, best in the 225-325mph zone where your instantaneous turn is maximized. The K-4’s engine strength is much of the problem. The K-4 cruises so quickly, climbs so effortlessly, and accelerates like a banshee, thus it can go from optimal speeds to extreme speeds in the blink of an eye.

At low speeds it feels like the engine drags you around as much as the wings creating lift. The leading edge slats and some flaps can really help. It gets a little tricky when slow because it requires a lot of manual input and gentle hand to keep yourself from flipping over on the engine’s massive torque (which actually overpowers the autopilot to the point that the aircraft won’t fly straight under trim). The leading-edge slats can feel a little destabilizing as they deploy/retract, causing a little “wiggle” in yaw. Use of more than 1-2 notches of flap should be reserved for stall fights or when you are very nose-high in a zoom-type climb. Flap create huge drag but the K-4 has enough power to overcome it better than most. Roll-rate is also speed sensitive in the same range, being average and not a strength to play to. Really be careful over ~425mph IAS, above that the controls start to become quite heavy in all axis and in an extreme dive it can be necessary to use trim to control the aircraft. I also tend to feel that as the K-4 uses ammunition up it tends to become a little better, not a surprise given the ammo alone weighs 200lbs. Also be sure to rid yourself of your drop tank, a common error that adds weight and drag, complicating the situation.

Flap speeds are 195, 185, 175, 165, and 155 IAS.

Fighting in the Bf 109K-4


One of the most exciting advantages of the K4 is the climbing ability. Most planes cannot follow the K4 in a climb especially if you keep your energy high after an attack. One promising strategy is, to fly high into the fight, boom in and zoom out without turning more than 45°. The K4 is not a good turner, it looses a lot E in a turn and one of it`s biggest drawback is it`s high speed compression. You have to use your trim to keep the plane balanced in a dive and if you are too fast, you have to nose up by hitting the trim key as often as possible. In this situation it may slightly roll to the side and will not respond to the alerions. So keep this always in mind, if you dive. Hold your speed below this point and -if neccessary- throttle back so you always keep controle over the plane.

For attacking, try to make quick passes at your opponent. I usually pick out a target, dive in below him, get in close, and when I hit D300, I cut loose with the 30mm from low and behind. This several things for you: 1) you have the speed to outrun the other planes untill drag catche up to you, and the few faster than you catch up. 2) He won't see you once you get below him, meaning you can get in closer. 3) It gives you a larger target than a shot from dead 6, meaning you're more likely to hit 4) The speed can also be used to climb back upto saftey, and repeat the process.

Only fire 1-2 rounds with the 30mm, and don't fire the 30mm and the 13mm mg's at the same time. The 13mm rounds distract you, and you can't keep track of your 30mm round.

Trim in a 109 is an important consideration and becoming familiar with the full range of trim available and knowing when to use it largely removes the 109's weakness of poor control response at high speed. Whenever your speed falls to a controllable level you can quickly restore normal trim settings using CTRL+X. Trim can be used as a supplement to stick input and with a bit of practice can be used instinctively to accurately aim the 109 or stay on a cons 6 at high speed. The trim keys are:

Elevator up = K Elevator down = I Rudder left = J Rudder right = L Aileron left = M Aileron right = , (comma key)

Note: trimming does not add extra turning ability, trimming is done in Aces High by moving your existing control surfaces not by adjusting trim tabs. Trim only overcomes the simulated heavy control surfaces at high speeds.

The 109K4 also is a very fast plane, but due to this, you may get some compression already in a level flight or a light dive. You may follow the fastest prop driven planes in the game for a while, but you should not do it for a long time.

The 109 is very vulnerable to hits to its radiators and oil. Oil leaks are common but a plus side is you’ll get quite a bit of time before your engine quits. The opposite is true of a radiator hit, if you get one your engine will be dead within a few minutes. If you aren’t close to a base you might as well go all out against whatever cons are in the area your as good as dead anyway.

If you are low and slow, use your flaps. This will tighten your turn radius and due to the strong engine you may accelerate after a turn and escape the enemy. Try to climb him out when you are in a save distance. Running level against fast late war planes may not be the best choice, but especially the fast allied (US)planes have problems to follow in a climb. The Spit XIV is the most dangerous match because it climbs and runs as well as the K4.

Fighting against the Bf 109K-4

In capable hands, the 109K-4 can be a whole lot of trouble. It’s right near the head of the class in terms of climb, acceleration and firepower. If it has positional advantage and/or time to work with, it can be a real handful

If attacking a K-4, try and keep the pressure on and see if you can’t get the K-4 into a lengthy turning defense. It helps if you come in with some energy advantage in speed or altitude. The more you can dictate the fight the better as the key is to not let the K-4 time to react or collect energy. Take whatever snap shots you get as the 109’s are not very tough and commonly take radiator and fuel hits that will dramatically limit the K-4’s options. Typically you’ll only get a couple of attempts to attack a K-4 before it starts to even the fight in terms of energy, which means it will then start to try and win angles or look for it’s own shot opportunity. Don’t overshoot the K-4, even if it appears to be too slow to be of danger, it can quickly accelerate and might get a snapshot as you pass by. Never turn your back even if the K-4 starts to run away unless you think you have enough separation to make your escape good. K-4’s have a nasty habit of returning shortly after they’ve left but this time they have the energy advantage. Most K-4’s are not going to be that well piloted though and will not use the full capabilities of the K-4 so aren’t too tough to beat. In most cases other aircraft have an advantage they can exploit or a capability they can match (or almost). If you press your strength, typically in turn-rate/radius, you can often make the K-4 a fairly easy kill. One last warning, don’t get sloppy around a K-4 because the can one hit kill you if given half a chance.

If jumped by a K-4 be very aware of the firepower and make your defensive maneuvers erratic and unpredictable. Many very good pilots fly the K-4 and won’t miss simple defensive maneuvers. Try and keep speeds in your favor, either getting above the K-4 comfort zone, i.e. taking the fight to 400+mph, or slow things down under 225mph. Most of the time K-4’s will sit and BnZ you from above and not engage in a turning fight. You can also typically use roll-rate to keep the K-4 out of phase and thus exploit a lagging lift vector angle (i.e. where it can’t keep up to your roll). A fun tactic is to pre-judge the K-4s diving attack, putting in a little dive yourself, suckering the K-4 past it’s optimal speed and then using that to gain an advantage (such as in a lag-roll to get behind them). The K-4 also isn’t great on rolling maneuvers be it scissors or reversals. The K-4 huge acceleration can quickly cause it to overshoot an enemy and give opportunities to sprinkle hits on the K-4 as it passes. Trying to cause an overshoot in a close situation is dangerous because a K-4 will typically throw a couple of 30mm your way in the process. In general it shouldn’t be too tough to defeat K-4 attacks as long as you remain alert and time your defenses correctly. The K-4 has a lot of staying power as long as it doesn’t fire away all its cannon ammunition so it’s best to ensure you implement an overall strategy for the fight, not just a point-in-time defense. This might be to escape towards friends or maybe to sucker the K-4 in close if you feel the have the means to do so and put the K-4 on the defensive. Be careful of what appears to a reversal where you are almost matched E, it might be a rope-a-dope where the K-4 is simply setting you up to stall out so it can dive back down and nail you

External Links

Soda's Aircraft Evaluations

Aces High Fighter Perfomance Comparison