Great 109 article

[Gman]

https://www.warhistoryonline.com/world-war-ii/20-amazing-now-images-wwii-adam-surrey-x.html

The DB605 starts explosively and easily, hot or cold. If any amount of throttle is left open, the aircraft literally jumps into the air with excitement. Throttle response is violently quick. There is no choking on excess fuel. This engine behaves like a nitroglycerin-powered dragster with a light flywheel. Moving the throttle too quickly produces 2600 rpm and full boost in ½ of a second. The prop design converts this power into seemingly infinite static thrust. I have no doubt this combination would challenge a new Porsche from 0 to 100kph. Pulling the spark plug cleaner handle changes the ignition timing, retards the rpm, and belches fire and smoke from the exhaust. The engine crackles and is slightly irregular at idle, as if it had a highly modified camshaft. The aircraft is saying, ”Do I have your attention yet? Because in a minute, I will demand all your courage, all your love of country, and a laser focus to fully utilize the forces I am about to reveal to you.”

Freely moving, automatic leading edge slats on a Bf 109E. By using high-lift devices, the handling qualities of the Bf 109 were considerably enhanced. Photo Credit.

Taxiing the airplane is easy. Blasts of power with frequent stabs of brake are needed to initiate turns, with no risk of the heavy tail coming up. In less than ten minutes, you must either take off or shutdown, due to rising radiator temps. Bf109 take-off drama is the stuff of nightmares. Everything you have ever heard is true. German aces all experienced loss of control accidents. Recent test pilots have not been immune either. Everyone will be challenged to the limits of their ability sooner or later. I thank German ace Oskar Boesch for giving me my Bf109E check out. Despite this preparation, the Bf109 has at times required everything in my playbook all in one moment, to keep under control. I treat this aircraft as a priceless jewel, changing all parameters of use to limit risk. Never use hard runways. Never accept more than a 10 knot crosswind on grass. Never use runways with any obstructions anywhere in sight. Does this sound too restrictive? Running off the runway should involve embarrassment, not injury. The pilot must respect the constraints of a design that permitted the wingless fuselage to be rolled into a rail car.

Poor ground handling traits are only partly caused by the narrow wheel track. The extreme tipped outward angle of the wheels as they meet the ground is what instigates most excursions off of the runway. If any more weight is placed on one main wheel than the other, that wheel gets enough traction to turn the plane to the other side. Every bump, crosswind, and the rotational torque from any power change makes this craft carve a turn like a toy wheel rolled while leaning to one side. You are not given the immediate yaw in one place that other tail wheel airplanes experience unless you try to land on a hard runway. Watching a Bf109 take off on grass from behind sheds much light. Once the tail comes up, the aircraft yaws to the side by 10 degrees. Each tire struggles for dominance over the other. Grass is thrown out in little rooster tails. Imagine each wheel as a heavyweight boxer in a title fight, with you as the undersized referee, too weak to guarantee complete control. To stop a divergent arcing turn, there is at your disposal one tiny rudder optimized for high-speed flight and brakes that were designed to taxi on 1000m square fields.

Messerschmitt Bf109 during refueling. Photo Credit.

Ground stability is further degraded by the high center of mass of the engine and the overpowering gyroscopic behavior of the propeller. Raising the tail fast gives such a large yaw to the left that the small rudder is unable to compensate. Oskar Boesch felt the most important information for me to learn was first, the correct rate of throttle movement from idle until tail raise, and second, the ideal rate of moving the control stick forward to raise the tail into the exact flight attitude. Huge increases in safety would come from that discipline alone. He put his hand on mine and rehearsed the exact speed of all control movements, imagining a glass of champagne sitting undisturbed on the panel through the entire takeoff roll. The Bf109 rudder must be frenetically moved to maintain heading on takeoff, never allowing the aircraft to diverge. It has been said that if the direction of take-off roll is allowed to change, one must not try to correct, but instead accept the new heading until off the ground. Attempts to correct with strong opposite rudder result in such severe oversteer, that the ensuing high-speed ground loop toward the other direction could be deadly. Can you see how this is unlikely to work on a narrow runway with trees on each side?

A Bf109 always skips a few times before starting to fly, as it must be convinced of your competence again and again before finally handing over the reins of control. Once airborne, acceleration and climb angle are extreme, and combined with runaway freight train acceleration downhill, this fighter plays the energy card better than most. The stick forces used in pulling out of a fast dive remind that German pilots were naturally assumed to be strong. Pilots are advised not to use trim to compensate.
Bf 109 G-4 W.Nr. 19310 on display at Technikmuseum Speyer.

The E model has a lightning fast roll rate and response at slower speeds, but stiffens up to match the competitors from cruise speed and up. The G is slower in roll than the E, but varies less with speed change. Roll performance in the G is similar to the Spitfire Mark IX, but feels better at high speeds. Fluid yaw stability is a shared trait of all the Bf109 series. It wants to be told what to do with the rudders every second and it delivers instantly, giving opportunity to yaw with minimal drag for a deflection shot or to provide subterfuge and evasion. Precise controls feel hand made and adjusted like a fine watch. Move anything one mm, and you will get exactly one mm of aircraft movement, with no slop or delay. There is the feeling of enough airframe rigidity and strength to fly through a tornado unscathed. Controls for radiator and propeller are switched into automatic once gear and flaps are retracted. All that is left is a desire to hunt.

Wing loading is high, even for a WW2 fighter. Leading edge slats automatically drift out during increased angles of attack to mimic a larger wing. It works brilliantly. On paper, the Bf109 should not be able to stay with a Spitfire in a turn. In the real world, half of the German aces claimed they were always able to stay with Spitfires and Hurricanes in turns. How is this possible? The Bf109 accelerated stall behavior was far more benign than its competitors, allowing pilots to play at the edge of control without penalty. At any speed and G load, slight relaxation of the stick instantly returned the stalled wing to normal flight. Lesser aircraft could not risk flying at the edges of their superior theoretical performance without losing more control than the Bf109.
Two 109s take-off at Duxford. Both are Post-war Spanish built Hispano Buchons and both also flew from Duxford in the late 1960’s during production of the ‘Battle of Britain’ film. To the right is ‘D-FWME’ which is now fitted with a DB605 engine and is effectively a BF109G-4. Left is ‘G-AWHE’ in a desert scheme. This Buchon is still Merlin powered and is generally operated by ARCo. They are seen getting airborne for the ‘Balbo’ at the 2015 Flying Legends Airshow. Duxford, Cambridgeshire, UK. 12-7-2015. Photo Credit.

Landing the Bf109G brings you into the final of this challenge match. Longitudinal stability and speed control befitting a DC3, combined with a steep nose down attitude and great visibility lull you into a false sense of security. The E model droops the ailerons as full flaps are rolled in, making roll response very heavy and approaches at 140kph. The G model needs 180 km/hr across the numbers to smoothly flare and land in a 3 point attitude, arriving like a clod of dirt. This plane sits down very well and suggests to you it does not feel like flying any more. Rollouts are short. I flew an E model out of an 800 meter grass strip with a 15 meter obstruction at the approach end without any problems. The Bf109 usually rolls straight after touchdown, but sometimes careens and arcs wildly off on a new direction as if you jumped onto a curving railroad track. Landing gear geometry, combined with high motor CG, aft longitudinal CG, and ineffective rudder, can demand occasional strong brake use to keep rolling straight. In comparison, take offs are far more traumatic. Aces said that if you survived the takeoff, you would likely survive the landing. Most pilots get out of the cockpit after a successful flight with a sheepish look on their face. They would look the same if a semi-truck ran a red light at 100kph and just missed them.

Listen to a Merlin engine and hear a beautiful symphonic sound. Listen to the Daimler Benz engine. The recipe for recreating this sound is to start with a Merlin. Put in a racing camshaft, jack up the compression, and then garnish with the shriek of 1000 tortured souls that is the DB605 supercharger. It is simply the most pure and sinister sound in the universe. Being attacked by something with this sound would make me curl up in the fetal position on the floor and cry like a little baby. Any exposure to this instrument of war will permeate your soul and imprint itself there forever. It moves a person like nothing else. Non-aviation people who stumble upon it at an air show can be talkative and laughing around all the rest of the aircraft, but when they lay eyes on the 109, all go quiet, not knowing but feeling this unstoppable force that is the Bf109G.

Witness the Bf109G. You will forever regard it with more reverence and respect than any other man made object.

[horble]

Cool writeup, that led me to search for this on youtube:

[Denniss]

Bah - that 109 image is mirrored as the air intake is on the wrong side

[GScholz]

Good read Gman. The 109 makes an impression on all who fly her. Horble, there's another cockpit recording out there. I only wish they could have fastened the camera a bit more securely. https://youtu.be/JGhMGQst4lo

[horble]

Bah - that 109 image is mirrored as the air intake is on the wrong side

Yes, that was driving me nuts.

[Mister Fork]

Notice how much control play there is on landing the 109? Especially on touchdown?  Kinda resembles mine when landing it. 

It's amazing to see how powerful those aircraft are! That G-4 really zoomed up quickly after taking off.  Still, compared to Aces High, it's a lot of work to get the 109 engine started. And it was also interesting to see that he only manipulated the throttle once airborne...no mixture or RPM changes needed...compared to a early/mid-war Spitfire or Hurricane he's be muddling with mixture and prop. Starting the 109 - gebuz, might as well be tapping one foot, rubbing your stomach, chewing gum, blinking your left eye, and humming The Star-Spangled Banner. But one running and flying, it's allll automated - engine cowling (cooling) flaps, prop pitch, mixture. Then it's the allied pilot doing the foot hopping, eye blinking, stomach rubbing during flight.

Good find guys!

[PR3D4TOR]

Great article. Some nice anecdotes on a special bird. 

[JOACH1M]

Sounds terrifying.... i like it!

[DaveBB]

P-38s sure could have used that spark plug de-fouler mechanism in the ETO.  Were any US or British aircraft equipped with that? Ingenious.

[Vraciu]

P-38s sure could have used that spark plug de-fouler mechanism in the ETO.  Were any US or British aircraft equipped with that? Ingenious.

It can be done manually with the mixture during a run-up.   Dunno if the auto system is useable in flight. 

[PR3D4TOR]

The DB 605's spark plug cleaner changes the ignition timing, allowing the fuel to wash the spark plug before ignition. I don't know of any allied engine that could change ignition timing anywhere outside of a workshop.

[Vraciu]

The DB 605's spark plug cleaner changes the ignition timing, allowing the fuel to wash the spark plug before ignition. I don't know of any allied engine that could change ignition timing anywhere outside of a workshop.

Fouling is usually caused by too much lead on the plug.   Dumping more fuel on it via a richer mixture setting would only make the problem worse I would guess.   By changing the timing they may be trying to get it hot so it melts the stuff off.   The same can be done by running the engine mixture very lean then running the power up until it burns the lead off.  There are a couple variations of this theme that accomplish the same thing.

[PR3D4TOR]

If the same could be done by running the engine mixture very lean then there would be no need for changing the ignition timing. The Germans were many things, but stupid was not one of them.

[Vraciu]

If the same could be done by running the engine mixture very lean then there would be no need for changing the ignition timing. The Germans were many things, but stupid was not one of them.

It can be done because I've done it dozens of times in my flying life.   Being stupid isn't the issue.

[PR3D4TOR]

Then why did they develop this system if all they needed to do was lean out the mixture?