Below is some useful information about the new synchronizers, rates of fire and key commands found in version 1.026 of ROF.
The following text and graphics about synchronizers was supplied to us and written by a Russian ROF user named Wad who is friendly with the team and has an engineerig background. He helped us research synchronizer technology in WWI and agreed to write this little primer for us.
A few words about machine gun synchronizers in WWI and ROF:
Many people know that combat aircraft of WWI were equipped with a special device that provides the pilot the ability to fire forward through the arc of a spinning propeller without the bullets striking the blades. And many people think that this device renders the machine-gun inoperative at the moment either blade is in line with the machine gun muzzle. At the present time all fixed machine guns in RoF are working in this way:
You can shoot:
And you can’t do it:
However, in reality, this is not so.
The first actual synchronizing gear was made by Anthony Fokker in the May of 1915. It consists of a cam wheel attached to the propeller shaft and a linkage system that transmits the reciprocating movement from the push rod resting on a cam to the trigger of the machine gun. The cam is adjusted so that it pulls the rod when the blade is not opposite the muzzle of the gun. So this device effectively turned the machine gun into the semi-automatic weapon. The pilot doesn’t press the trigger of the gun, but he just engage the synchronized gear and the cam of this gear fired one shot for each turn of propeller if the gun has time to recharge. The firing of the gun is controlled by a Bowden wire lever attached to the control column of the airplane.
This synchronizer was called “Fokker gear” or “Stangensteuerung” and was installed on Fokker E.III and some early German two-seaters in the summer of 1915:
After several months of defeats, the French have copied this device with minor modifications. This synchronizer was called “Alkan-Hamy gear” by name of its developers: Junior lieutenant of the French air service Alkan and naval engineer Hamy. This gear was installed on Nieuport 17 in the May of 1916:
The first British synchronized gear was put into production early in 1916. The “Vickers-Challenger gear”, as it was named for the inventor: George Challenger, an engineer of the Vickers establishment, involved a long oscillating rod to activate the Vickers trigger controlled by a cam and reduction gear attached to the rotary engine pump spindle. This synchronizer was fitted to a Bristol Scout in the January of 1916:
On a mission to England, lieutenant-commander Victor Dibovsky, an officer of the Imperial Russian Navy suggested a synchronized gear of his own design, and Warrant Officer F. W. Scarff developed and realized this gear which also consisted of came and rods and worked in much the same way as the Fokker gear. Most of the Sopwith 1 ½ Strutters delivered to RNAS (Royal Naval Air Service) in 1916 was fitted with the Scarff-Dibovsky gear:
Fokker gear worked satisfactorily on the aircrafts with rotative engines but it had troubles with stationary engines due to the increased length of the rods. For this reason the new German fighter of 1916 year, Albatros D I, was equipped with its own synchronized gear which was named “Hedtke gear” or “Hedtkesteuerung”:
All of these systems operate on the same principle: a cam mounted on the engine’s shaft presses the machine gun’s trigger through a system of rods and generate thereby one firing impulse for each rotation of propeller shaft.
From this it follows that a rate of fire strongly depends on engine speed.
Indeed, if the engine is stopped you can’t fire the gun! If you press the trigger on the control column you just engage the synchronized gear and nothing happens then because all parts of the gear are not on the run but you will able to shoot as soon as you start the engine.
How exactly the rate of fire depends on engine speed?
Suppose the claimed rate of fire of machine gun is 450 rpm (Spandau).*
If the engine speeds is up to 450 revolutions per minute - the rate of fire is same as the engine rpm.
But the gun cannot exceed its own rate of fire! As soon as engine speed exceeded 450 rpm, the gun would not have time to recharge and every second stroke of synchronizer rod would be blank.
Therefore, the rate of fire on 451 rpm dramatically dropped down to 225 rounds per minute and the machine gun would fire only one shot at every other rotation of propeller.
Then, if we continued to increase rpm, the rate of fire would grow again up to 450 rounds per minute on 900 rpm and would drop off after that to 300 rounds per minute. The machine gun would fire only one shot at every third rotation of propeller.
The dependence of rate of fire on rpm is shown there:
These graphs show that the rate of fire is highly dependent on motor speed. However, this dependence can be significantly reduced by increasing the number of synchronizing pulses, but this is hindered by the force of inertia of the system. So, further efforts of gunsmiths have been directed at reducing the force of inertia. Their researches moved towards these areas:
1. Pulling is better than pushing.
If you pull on the rod, this rod can be made quite thin, and the force of inertia will be minimized. This principle was realized in the British Sopwith-Kauper synchronized gear, invented by Australian motoring-pioneer H. A. Kauper. This gear is the inverse of Fokker design: the firing impulse generates at each low point of the cam instead at the lobe of the cam as a Fokker’s gear did. It was adopted in some Sopwith machines in 1917.
2. Oscillating is better than pulling.
Marc Birkigt, ingenious French engineer and inventor of the engine “Hispano-Suiza” suggested the use of the shaft, rotating alternately in clockwise and counterclockwise. The inertia of the oscillating motion is smaller than the inertia of the reciprocating motion, so the device, which is based on this principle, can operate at higher speeds. Birkigt gear was adopted by the French Air Force in September, 1916 and was in use up to the World War II.
3. Move a cam into the gun.
In the end of 1916 Antony Fokker designed a new synchronized gear without any rods at all. His idea was to move the cam directly on the gun. This gear consists of the flexible shaft connected with the end of the engine camshaft through the disengaging clutch. The opposite end of this flexible shaft connected with the cam of the trigger motor fitted to the machine gun. There were four balls in the case of the trigger motor which functioned as automatic safety device and prevented accidental discharge during engine start. This gear became standard on German air force since 1917.
4. Precision hydraulic system.
The Constantinesco gear, invented by Romanian engineer M. Constantinesco, became standard on Royal Air Force in 1917. Its action is hydraulic. A pump attached to the engine transmits impulses to a pipe-line filled with oil under pressure. A similar pump fitted to the gun responds to these impulses and fires the gun at the desired moment, so that the bullet will pass between the blades of the propeller.
All of this advanced gears generated two firing impulses per propeller revolution, so the dependence of the rate of fire on the engine speeds would be like this:
According to information received from the developers all of these features would be implemented in a future update.
*Note: Author uses a rate of fire for the Spandau of 450 rounds per minute in the explaination above. The Spandau had an adjustable rate of fire. We have set it at 650 rpm in ROF.
This information can be downloaded from here in .pdf form.
Types of synchronizers in ROF
"Hedtke" actuator, mechanical hard link, 1 impulse per propeller cycle.
Albatros D.II late
"Semmler" actuator, mechanical hard link, 1 impulse per propeller cycle.
"Stangensteuerung" actuator, mechanical hard link, 1 impulse per propeller cycle.
"Zentralsteuerung" actuator, mechanical soft link and min. RPM limit, 2 impulses per propeller cycle.
Halberstadt CL.II 150hp
Halberstadt CL.II 180hp
"Sopwith-Kauper" actuator, mechanical hard link, 2 impulses per propeller cycle.
"Constantinesco" actuator, hydraulic link, 2 impulses per propeller cycle.
Bristol F2B Fighter (Falcon 2)
Bristol F2B Fighter (Falcon 3)
"Alkan-Hamy" actuator, mechanical hard link, 1 impulse per propeller cycle.
"Birkigt" actuator, mechanical hard link, 2 impulses per propeller cycle.
SPAD 7.C1 150hp
SPAD 7.C1 180hp
"Challenger" actuator, mechanical hard link, 2 impulses per propeller cycle.
Maximum Rates of Fire for ROF Weapons
Lewis - 550 rpm (if magazine had 550 rounds)
Vickers Mk.I - 500 rpm (1916)**
Vickers Mk.I - 750 rpm w/ Hazelton Muzzle Booster (1917-1918)
Vickers Balloon Gun - 600 rpm
Spandau 08/15 - 650 rpm
Parabellum LMG14 - 700 rpm
Becker 20mm Automatic Cannon - 300 rpm (if magazine had 300 rounds)
Davis - 3 rpm (yes just 3!)
**Note: Includes Sopwith Pup, Sopwith Triplane. Nieuport 17 and Spad 7 150hp.
Weapons Controls in ROF
The following information was prepared by LukeFF about how weapon controls work in ROF version 1.026.
One of the new features of Rise of Flight version 1.026 is the way in which guns are charged, reloaded, and fired. Each of these features is discussed below.
Recharging and reloading your guns:
Rise of Flight now uses a new system to charge/recharge and reload your guns. As opposed to earlier versions of the game, the R key (All guns recharge / rearm) now controls all aspects of recharging and reloading your guns. No longer are guns able to be recharged simultaneously. When you press the R key, each gun that needs to be recharged will be recharged in sequence, followed by any guns which need to be reloaded (also in sequence).
In short, this new system is based upon two simple concepts:
- Only guns which need to be recharged will be recharged.
- Only guns which need to be reloaded will be reloaded.
There are several new gunfire commands implemented in version 1.026. Each of these is described below:
- All guns fire (Space): this command operates the same as in previous versions of the game. All guns which are charged and have ammo will fire with this command.
- Forward-facing guns fire (Right Alt + Space): this command only fires guns which are currently aligned to converge with your gunsight. This means that any upper-wing mounted guns which are tilted to fire upwards (see below) will not fire with this command. In addition, the Lewis machine gun as mounted on the Albatros D.III, the Albatros D.Va, and the R.E.8, and the Becker automatic cannon as mounted on the two versions of the Albatros D.II will not fire at all with this command, as they are not fitted to converge with each plane’s respective gunsight.
- Nose guns fire (Left Alt +Space): this command only fires the guns fitted to the nose of your aircraft.
- Overwing guns fire (comma): this command fires all guns mounted to the upper wing of your aircraft, regardless of the angle at which they are tilted.
- Wing-guns fire (period): this command fires the two Lewis machine guns mounted on the lower wings of the Sopwith Dolphin.
Moving the upper-wing mounted guns:
Any gun that is mounted to the upper wing of your aircraft, if capable of movement, can be moved up and down in order to change the magazine or in some cases the angle at which it fires. Typically this is 45 degrees up angle for Foster mounted weapons. To do this, press the Left Alt + R key combination (Elevate / Depress guns).
Note: if one of your upper-wing guns needs to be reloaded, you do not need to use this command before using the All guns recharge / rearm command. In such cases the animation of the gun being pulled down and subsequently pushed back up will play automatically. The same is also true for recharging guns, although with some aircraft the gun will not be pulled down before the recharging animation plays. This simulates the ability of pilots to reach up and pull the charging handle without needing to get up out of their seat. Aircraft currently simulated in this manner include the Albatros D.III, the Albatros D.Va, the Nieuport 11, the Nieuport 17, the S.E.5a, and the Sopwith Dolphin.
We think you will enjoy the new more realistic weapon mechanics found in version 1.026. There are always compromises that need to be made when creating such systems in a flight-sim, but we feel these new features add a depth and technical achievement unmatched in the flight-sim genre. Special thanks to Wad and LukeFF for their assistance in gathering this information.
Thanks to the community fror your patience as we worked to finalize these changes.
We hope you like them!