Dev blog #117
22.12.2015
Dev blog #117
Hello everyone!
 
Tomorrow beta-testers will start checking version 1.106 release candidate, which we plan to publish next week. Today we'll tell you about another addition you'll see in the new update - redesigned airfields / tank spawns screen. We received many requests to get rid of the 'radar rings' around the bases that show enemy and friendly units and decided it's better to remove this legal cheat, simultaneously making the airfields design a bit more user friendly and fitting for the scenarios game server owners host. The initial idea of a 'radar' was to make ground control personnel transmit the nearby situation by radio, but it quickly became clear that this ends in an endless stream of situation reports, so the current 'radar' representation won. However it appeared too abstract for many players. That's why we remove these 'radar rings' and replace them with special marks: 'under air attack' and 'under ground attack'. Moreover, in many multiplayer scenarios created by players some airfields and tank spawns are really close to each other, making selecting them a bit tricky, so we redesigned their symbols to be more compact. Here are some screenshots showing the changes in the multiplayer airfield selection screen:
 
How it was:
 
_MPmap_unselected_old.jpg _MPmap_DED_old.jpg
 
How it will be:
 
_MPmap_unselected_new.jpg _MPmap_DED_new.jpg
 
We told you about the upcoming plane, MiG-3, in our recent developer diary. After this one, we'll make four more planes available during January and February to owners of Battle of Moscow, whish is planned to be released in March: Bf-109 F-2, IL-2 mod. 1941, Pe-2 ser.35 and Ju 88 A4. Some of them are almost (70%) ready.
 
Bf 109 F-2
This German fighter looks like its descendant, F-4. There are only two significant visual differences: angular landing gear bays and smaller radiator intake. However this aircraft is 100 kg lighter, it have less caliber nose autocannon MG-151/15, and has another engine, DB-601N, that requires more complicated management at limited time modes:
 
2300 RPM, 1.15 ATA - unlimited;
2400 RPM, 1.25 ATA - 30 minutes combat mode;
2600 RPM, 1.35 ATA - 3 minutes emergency mode;
2800 RPM, 1.42 ATA - 1 minute boosted mode.
 
Its flight characteristics are on par with its later version, so it will be a most dangerous adversary in Battle of Moscow time frame.
 
__Bf109F2_1.jpg __Bf109F2_2.jpg
__Bf109F2_3.jpg __Bf109F2_4.jpg
 
IL-2 mod. 1941
This is the Soviet sturmovik in its initial design, not yet hampered by metal and armored glass shortage. Unlike later models, this early one has metal wings and fuselage and weight compensators (special extending weights that move together with ailerons and the rudder). Back cockpit is made of plexiglas and armored glass, allowing for the great view back and up, arguably the best view in this direction among all single engine planes in the game. Its armament is similar to 1942 model with the exception of Sh-37 gun. In addition, we couldn't find a photograph or any document proving that VYa-23 guns were installed on planes with early back cockpit, so choosing these guns makes the back cockpit metallic like on 1942 model.
 
__Il2m41_1.jpg __Il2m41_2.jpg
__Il2m41_3.jpg __Il2m41_4.jpg
 
Pe-2 ser. 35
Early Pe-2 had more complex gunner cockpit design, which could be closed to not interfere with the plane aerodynamic characteristics in normal flight. Under attack, the gunner opened it by sliding the back part into the fuselage, and fired his machine gun. Unfortunately, only 7.62 mm ShKAS was installed there, not 12.7 mm UBT like on later model. Moreover, the cockpit of this early models allows for a much better view forward and down. This plane was equipped with M-105RA engines, which are weaker than M-105RF used in Pe-2 ser. 87.
 
_Pe2s35_1.jpg _Pe2s35_2.jpg
_Pe2s35_3.jpg _Pe2s35_4.jpg
 
Work on the Moscow map is proceeding as planned. As we said earlier, it won't be possible to fly over the city itself, but you'll be able to fly right next to it. In addition, some buildings at the western ountskirts, including unique ones, can be reached, so they have an increased detail level. For example, Moscow Northern River Station:
 
_Msk_Riverport_1.jpg _Msk_Riverport_2.jpg _Msk_Riverport_6.jpg
_Msk_Riverport_3.jpg _Msk_Riverport_4.jpg _Msk_Riverport_5.jpg 
 
We'd like to finish the today diary by telling you one story - as example how we work on aircraft flight model and various dynamic effects analysis. Some time ago several customers, who have real life experience of piloting light planes, asked us: "Why in real life an aircraft pitches down after extending flaps, but in the sim it pitches up?" We started by checking momentum data on La-5 and comparing it to wing tunnel test data of a real (full scale) La-5 (it comes from Central Aero-Hydrodinamic Institute, wing tunnel T-101):
 
_Mz_1.jpg _Mz_2.jpg
 
This means that a plane without flight stick input will be rebalanced to a lesser angle of attack level after extending flaps just like it happened in real life. But there is a reasonable question - since in real life a plane pitches down, why this doesn't happen in the game, although the angle of attack change caused by flaps extension is correct?
 
First:
 
1. Pitch down momentum caused by flaps extension leads to trim angle of attack decrease at the same flight stick position;
2. The increase in ascensional force from flaps is much greater than its decrease caused by diminishing angle of attack;
3. The resulting ascensional force increases, causing positive g load and increasing the flight path angle between the velocity vector and the horizon plane;
4. The plane pitch (the sum of the flight path angle and the angle of attack) drops sharply at first, while flight path, being more inert, is not yet increased enough. In the sim you experience this as a brief pitchover like a car brake dive;
5. Later the plane trajectory pitches up significantly and the flight angle increase is more than angle of attack decrease. It happens because the decrease of angle of attack is limited by the new trim angle of attack, while the increase of the flight angle is not limited by anything while velocity and ascensional forces are not decreased yet.
 
Second:
 
It is very important to understand the forces affecting the flight stick and what happens to the plane with the same flight stick position. We just discussed what happens with a plane. What happens with the flight stick? It tries to move from you forward, to dive position, because the air flow is changed after flaps extension, it now moves further down after leaving the wings. This affects the elevator, pushing it down too, which affects the flight stick linked to it. So the flow downwash caused by extended flaps affects the elevator, which in turn affects the flight stick, trying to pitch the plane down.
 
These are theoretical conclusions, so it would be great to perform an experiment on a real plane that is similar to WWII era fighters modeled in the sim. Thankfully, an old friend agreed to help us with this experiment in the cause of science: flight instructor and professional aerobatics pilot Konstantin Borovik.
 
_Const_1.jpg _Const_2.jpg _Const_3.jpg
 
Konstantin is experienced aerobatics pilot who has many awards and who got silver medal in Russia championship this year in Yak-52 class, so there is no doubt in his professional expertise. For example, here is the video of one of his training flights on Yak-52:
 
 
When Kostya agreed to help us to perform our little experiment, we asked him to do the following:
- Fly level at the same speed when you need to extend the flaps before landing.
- Fix the flight stick in the position that allows for balanced level flight and then release the flaps.
- Force the flight stick to remain in the same position for several seconds regardless of the forces affecting it after that.
 
It was necessary to note three things:
1. How the plane pitch changes during these several seconds;
2. How forces affecting the flight stick change;
3. What climb indicator shows.
 
Next day Kostya was at the airfield and did what we asked during a routine training flight. Here is his brief report:
1. At initial 170 km/h speed flaps extension leads to sharp speed drop to 120-110 km/h
2. The plane pitches up
3. Climb indicator shows increasing vertical speed
4. Flight stick tries to move forward from you
5. This leads to speed loss and downward pitch, which in turn leads to speed increase.
 
The most precious result of this experiment is that we have the video Kostya kindly recorded:
 
 
This small experiment shows that plane behavior in the game after landing flaps extension is much like real plane behavior with a similar airframe and flaps. Two different effects happen simultaneously: the force affecting the flight stick pulls it from pilot while the plane, because the flight stick is fixed, pitches up. If pilot won't compensate for the stick movement forward, the plane will pitch down. However, in the game you don't have this feedback caused by downwash and joystick won't move by itself as it should, causing the plane pitch up instead. It's a limitation of not 'feeling' the simulated plane like you would do a real one.
 
The only issue remains is that the effect that pulls the stick from you isn't modeled on Force Feedback joysticks, we plan to address this sometimes in the future. Kostya - thank you very much!