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Gavrick

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Everything posted by Gavrick

  1. In this report http://www.spitfirep....com/aa873.html stall speed - 81...90 m.p.h. with flaps and undercarriage up and 71 m.p.h. with flaps down. And, dont forget, that airspeed indicator has position error. -4 m.p.h. at low speed, that statued in flight manual. So, real stall speeds near- 85...94 and 75 m.p.h. (flaps up/down). And, if the stall speed were 73 miles per hour from pilot manual, then lift coefficient Cl should have been about 2.0 (for 3000kg Spitfire). This is fantastic value. I think, that is theoretical number, recalculates from early Spitfire. In the report above there is an example of such a recalculation with similar numbers.
  2. The Spitfire really had an interesting feature in longitudinal channel controlablity. As already mentioned, Spitfire was a statically neutral airplane. As one of the manifestations of this - during acceleration or braking, the balancing position of stick does not practically change with it (see the excerpt from the NACA report). Unlike a conventional stable airplane, in which the lower the speed, the more you have to pull on yourself to maintain the balancing. That is, if you, for example, dive on the Spitfire - hold the stick the way it is set, the plane will accelerate and fly straight. But, at the same time, due to the peculiarities of the weight compensation of the elevator, force on the stick is changing, and strongly. And indeed, if you accelerate in a dive, then as the speed increases, stick will tend to go "on yourself", so the pilot has to push it away more and more from itself (that is, apply the same effort as on a stable aircraft), or twist the trimmer On the dive. Note - the forces applied to the stick vary, but the stick itself is practically stationary. Therefore, yes, indeed, as the speed increases, the aircraft must be trimmed to dive, and at the maximum permissible speed the trimmer must be twisted to a dive for the greater part of the stroke. By the way, on the indicator of the position of the trimmer, which is on the dashboard, the neutral trimmer on the handlebar is an arrow half a turn up from the neutral on the instrument. The range of the deviation for the dive is greater than for the trimming three times.
  3. The recovery time of the engine after a limited mode will be checked.
  4. About Spitfire stall. Spitfire is keep controllability in the stall. NACA report from Spitfireperformance: http://www.wwiiaircr...-V-Stalling.pdf Conclusion from this report: In general, from flight records from this report: Spitfire has unusual stall characteristics, motion beyound the stall is not violent and airplane still have lateral controllability. If you hold stick in position, required to start stall, airplane does not have a strong tendence to roll. If you continue pull stick, you may control aircraft by rudder and elevator beyound the stall. And from british flight tests (http://www.spitfireperformance.com/aa873.html): "At about 90 m.p.h. A.S.I. a considerable amount of buffeting around the hood commences. The A.S.I. can be reduced to 81 m.p.h. but at this speed sharp fore and aft pitching occurs together with increase of buffeting. This sharp fore and aft pitch prevents the control column from being held fully aft. In general the stall of the aeroplane is not clearly defined. There were no signs of either wing tending to drop. The elevator is moderately heavy though effectiveness has fallen off considerably."
  5. Thanks to everyone for the technical details found. Some materials I have not met before. As time will be, I will study and take into account.
  6. Yes. And you can check brakes by pressure in brakes gauge, at left side of control panel.
  7. Lets take a look to fig.9 and fig.11 from you link (NACA test report). Data at this figures taken from a sustained horizontal flight with different airspeed. We can evaluate the grade of static stability of the aircraft, based on these data. fig.9, Gliding condition (flaps and gears up), elevator angle at 100...120 mph is near 4...5 degree down. fig.11, Landing approach condition (flaps and gears down), elevator angle at 100...120 mph is near 3...4 degree down. That is, in this way, when flaps and gears down, elevator (and stick) remains almost in the same position as when flaps and gears up. Stick movement induced by pitching down moment is very small.
  8. As I understand, this video uses inserts from the movie "The First of Few", 1942.
  9. 162 Hello everyone! So, let's talk about Supermarine Spitfire Mk.VB. It took off for the first time in December 1940. Spitfires V were relatively old planes by the time the battle of Kuban begun in Spring 1943. "VB" variant was armed with two 20 mm Hispano Mk. II guns and four Browning .303 machine guns. The guns were magazine-fed, 60 rounds per gun, while machine guns had 350 rounds per gun. The lend-lease aircraft sent to the USSR did not have bomb-carrying capabilities, some other equipment was also removed - gun camera, landing lights, IFF transponder, etc. Thanks to this, the aircraft became lighter roughly by 40 kilograms. The special snowguard was installed in front of the engine supercharger to protect it from dust or snow while taking off. Most of the planes sent to the USSR had Merlin 46 engine, but roughly one-fifth of them was equipped with Merlin 45. They differed by critical altitudes - Merlin 46 was designed for higher altitudes like 4-5 kilometers, where it was more powerful, but it was 80-100 HP weaker than Merlin 45 near the ground. Our sim will represent both engines (Merlin 45 will be a modification). Spitfire instruments are similar to other planes, but there were some peculiarities. It was equipped with the rudder and elevator trimmers and the elevator trimmer position was shown on the instruments panel. The pitch up range of the trimmer is three times larger than pitch down. The engine-propeller combination is controlled by the throttle, the automatic pressure limiter switch, the propeller control unit and the mixture control assembly. The throttle is linked to the automatic supercharger: when the throttle is set to any position from 1/3 to full, it sets a pressure supported by the supercharger from -7 to +12 pounds per square inch (PSI) relative to one atmosphere pressure. So 760 mmHg boost equals to 1 ATA and to +0 position on the British boost indicator. The automatic pressure limiter can be turned off to maintain constant +16 boost regardless of the throttle position. The automatic mixture controller maintains the optimal mixture setting if its control level is in the forward position or leaned mixture to save fuel if its control level is in the back position. The mixture control system has been removed on later Spitfires. Water radiator is controlled by the lever to the left of the pilot seat which has six fixed positions and is set to 40% by default. The fuel gauge indicates the amount of fuel left in the feeder (bottom) tank when the fuel gauge button is pressed. In the sim, the pilot automatically presses the button twice in a minute if he doesn't do active maneuvering. The amount of fuel left in the upper fuel tank can't be indicated. Spitfire is equipped with a siren that warns a pilot if the throttle is set to a low position with the landing gear retracted. It turns off when the pilot either lowers the landing gear or increases the throttle or turns it off manually (in our sim the pilot turns the siren off after 3-5 seconds on its own). The sideslip indicator isn't a small ball like on other planes, but an arrow. It functions essentially the same - there is a pendulum behind the instruments panel attached to this arrow. The aircraft is equipped with two compasses - magnetic and gyro ones. Gyro compass should be caged up on the ground and while doing aerobatics (in the sim the pilot does on its own). There is a flight timer on the clock that is turned on by the pilot on its own after takeoff and turned off after landing. Upper and bottom formation lights can be turned on simultaneously or independently (RAlt+L). The horizontal marks on the collimator gunsight are adjustable, so you can use it like a rangefinder. To do this, enter the target distance in yards and the target base (its wingspan) in feet by pressing RAlt + , RAlt + ; and RAlt + /. There is a sun filter on the gunsight. While taxiing, keep in mind that Spitfire has narrow landing gear and large wings stuffed with weapons and ammunition, so they may touch the ground if you attempt a sharp turn, it also tends to 'circle'. On the other hand, it is stable on the runway during takeoff or landing. Its tail wheel rotates freely and does not have a lock. Take off should be made at 3000 RPM and +12 boost with the landing flaps retracted. When airborne, reduce the boost to +9 and RPM to 2850 and climb in this mode. The elevator is very sensitive and has very small stability reserve (the aircraft has a neutral static stability), so control the plane by gentle flight stick movements and don't overdo it. The pre-stall warning shake comes early, but if you continue to pull the flight stick and don't move it forward, the plane may stall and spin even at high speed. Flight manual says that you may enter spin only by a written permission of your squadron commander. Having the papers ready, enter the spin bravely - to recover from the spin, setting the control surfaces to the neutral position is enough usually. As we mentioned above, the aircraft has a neutral static stability. Therefore, the balanced flight stick position doesn't change during level flight while accelerating or decelerating. However, due to the elevator peculiarities, the flight stick load will change and the pilot should push the stick forward harder as the speed increases. That's why the elevator trimmer has the large pitch down range. The elevator effectiveness is high, so any trimmer position could lead to high-g accelerations (and force pilot to blackout rapidly) at higher speeds in spite of the limited control surfaces effectiveness at high speeds. The aircraft, especially untrimmed, should be controlled carefully at high speeds, not giving too much flight stick input since the high-g accelerations can potentially lead to a catastrophic structural failure. The aircraft becomes somewhat unstable with extended landing flaps, but in spite of this, it is easy to land. It's recommended to keep 95-100 MPH speed on the glide path. To summarize, Spitfire is a maneuverable, relatively easy to control and decently armed aircraft. However, its maneuverability (that comes from its large wing surface of 22.5 square meters, while Soviet fighters had ~17.5 sq.m. and Bf 109 had 16.2 sq.m) comes with the price of modest maximal speed near the ground. https://youtu.be/MgL_nLVGmng You can discuss the news in this thread
  10. Full news - here is a full text and visual materials You're very welcome to subscribe for new videos hereYou can ask new questions in this thread
  11. 145 Hello everyone, Fw 190 A-3 flight model revision that we promised long time ago is nearly finished. As we pointed earlier, flight model tuning in a sim is always a task of aircraft reconstruction with many unknown variables. Part of the data is missing and some values are just plain wrong, sometimes directly contradicting each other. And sometimes the missing data appears when an aircraft is released, that's why we need to correct FM sometimes. So, what will be changed in Fw 190 A-3 soon: - Wing twist has been changed. The wing root had 2 degrees angle of incidence that was steadily reduced to 0 degrees at two thirds of the wing span. Because of this, stall at high angles of attack will begin near the wing root and not on the entire wing surface at once, resulting in 'softer stalling'; - Aircraft center of mass position has been corrected (it was shifted forward by several centimeters); - Critical angle of attack and maximum lift coefficient increased. Stall speed of the aircraft decreased to 175 km/h; - Drag at high angles of attack decreased thanks to lift/drag curve data of a trophy aircraft tests in VVS Research Institute; - Propeller thrust decreased somewhat. Takeoff run of the aircraft with standard loadout is roughly 500 meters and takes 18 seconds, which corresponds to historical data. Because of these changes, aircraft handling changed slightly. It stalls differently. Spending fuel affects its center-of-gravity position more. A pilot would need to use the entire range of the adjustable stabilizer depending on the flight mode for comfort handling. In the same time, aircraft speed and climb rate remained almost the same. Meanwhile, we continue work on Fw 190 A-5. While being very similar to Fw 190 А-3 visually, it will have significantly different features and pecularities in loadouts and handling. You can discuss the news in this thread
  12. Full news - here is a full text and visual materials You're very welcome to subscribe for new videos hereYou can ask new questions in this thread
  13. It is pneumo re-cocking handles. Each Yak-1 gun has two cocking handle - mechanical and pneumatic. In BOS, while you on the ground and engine not working, if you reload guns, you use mechanical handle. After engine start - you use pneumo handle.
  14. 140 Hello Everybody, My name is Roman and I'm one of the Aerodynamics/Software Engineers for the IL-2 Sturmovik project. I create aircraft flight models together with my colleagues. I worked on the Yak-1b series 127 which was just released and now I work on the Bf-109 G-4, but I'd like to tell you about our plans in the medium term regarding the Fw-190. We'll begin working on the Fw-190 A-5 relatively soon, at the end of winter, and when we do that we’ll have a chance to also correct the existing Fw-190 A-3 flight model, taking all the data we have recently acquired into account. The aircraft we recreate in our sim flew more than 70 years ago and this is a long time. Aviation historians have written many books on this aircraft in general. However, many original documents were either lost or there is no way to access them in government archives where they are kept. That's why such documents are interesting for us and sometimes are found only after the work on a plane in question is already finished. Such documents are needed to correct flight model after release and sometimes when we use data from those documents they introduce significant changes. When we were working on Fw-190 A-3 we didn't have data that could allow us to pinpoint its stall speed and maximum lift coefficient, two directly linked values. We didn't have its wind tunnel data and the maximum lift coefficient calculated from the wing profile somewhat differs from its value on the real aircraft. Also, its stall speed wasn't clearly given in the reports we had. For example, the flight manual mentioned the landing speed with flaps and a rough estimate of its landing speed increase without flaps, but these values can give only an approximate stall speed. The stall speed was mentioned in the British report on captured aircraft flight tests - but the mass of the aircraft, an important parameter for calculating the maximum lift coefficient using the stall speed, was omitted from that report. Last year some new data appeared on the Internet - excerpts from the Fw-190 Chalai-Meudon wind tunnel data report. We used this data directly and reduced the maximum lift coefficient to 1.17 as it was given in this report. This turned out to be a mistake as some people on our forums suggested. The mistake was verified by the full report, kindly submitted by the community member II/JG17_ SchwarzeDreizehn. The summary graphs of this report did not take into account the flow disturbances and the relatively low flow speed in the tunnel, which lowered the maximum lift coefficient results. At the moment, we continue to analyze the data we have in hand. Our estimate of the Fw-190 maximum lift coefficient is now 1.3-1.4. Increasing the maximum lift coefficient will also increase the maximum angle of attack. Pitch range of the flight stick till stall will be widened, making the aircraft easier to handle. The Fw-190 had an unusual wing warp as proven by documents which were found thanks to the community’s help, however, these documents have slight discrepancies. Changing this warp will result in different stall behavior, it's likely to become 'softer', but only after flying the corrected plane in the game can this be tested. The main performance characteristics - speed and climb rate - should remain the same. We would like to thank all the people who helped us in the search for additional documents. II/JG17_SchwarzeDreizehn, JtD, II/JG11ATLAN, JG13_opcode and all others who kept the discussion polite and constructive - it's a pleasure to communicate with you and recreate the aviation history in our sim together! To finish the today's Dev Diary, we'll show you the corrected and newly added Fw-190 A-3 skins made by paintjob devotee I./ZG1_Panzerbar who we continue to work with: You can discuss the news in this thread
  15. Full news - here is a full text and visual materials You're very welcome to subscribe for new videos hereYou can ask new questions in this thread
  16. Same engine, but another airscrew. ViSH-61 at 69 series, and ViSH-105 at 127 series. That airscrew has different in blade angle limits. ViSH-61 with M-105PF can not reach nominal RPM (2700) while airplane stay on ground or have small speed (V=0...80 km/h), but ViSH-105 can. And ViSH-105 have more thrust at that low speeds range. With 15% throttle Yak-1 s127 start taxiing while startup procedure.
  17. It is not true. Do not fool people, Kwiatek. http://forum.il2sturmovik.com/topic/26139-new-yak/?p=410889
  18. Gavrick

    New Yak

    In real life max speed test performed with radiator flap set 'by airflow', that corresponds ingame 50%/35% for oil/water radiators. IRL data for Yak-1 s127 - max speed at 4km altitude - 591 kph TAS, ingame - 490kph IAS / 599kph TAS. 8 kph or 1.3% TAS mistake. IRL data for Yak-1 s127 - max speed at 6km altitude - 572 kph TAS, ingame - 436kph IAS / 594kph TAS. 22 kph or 3.8% TAS mistake. Where is "50-40 kph mistake"?
  19. Default - LShift+B. But it work only with 1st supercharger stage.
  20. About La-5 canopy. From La-5 frontline trials test report: -Canopy can not be opened at high speeds. Canopy self-closes during gliding descent because of weak canopy lock in open position. (Фонарь кабины невозможно открыть на больших скоростях, а на планировании, благодаря неудовлетворительной работе замка, фонарь сам закрывается.) IL-2 canopy wasn't locked in open position at all.
  21. Single-engine flight: - immediately drop all bombs, - If possible, do not reduce speed under V=250km/h, descend, if necessary - altitude cannot be held by loosing airspeed, - On the running engine - set 1.25ATA / 2400 RPM (climb mode), - Feather propeller of the damaged engine, and close cowl flaps of the damaged engine. - Chek flaps and gears- they are should be retracted. Single-engine landing: - Flaring of from single-engine landing is impossible, if gears and flaps are lowered, - Flaps set to 25 (take-off position), set flap to 50 (landing position) only if land has been started from too high altitude.
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