|
|
|||||||
| IL-2 Sturmovik The famous combat flight simulator. |
 |
|
|
Thread Tools | Display Modes |
|
|
|
#1
12-17-2007, 01:01 AM
|
|||
|
|||
Quote:
You may be saying that introducing more throttle (power) will cause the governor change the prop pitch to take a bigger bite of air to hold the RPM's the pilot set. Am I getting close to what you mean? Last edited by BSS_Sniper; 12-17-2007 at 01:14 AM. 
|
|
#2
12-17-2007, 05:02 AM
|
|||
|
|||
|
http://www.faa.gov/pilots/training/handbook/
ADJUSTABLE-PITCH PROPELLER Although some older adjustable-pitch propellers could only be adjusted on the ground, most modern adjustable-pitch propellers are designed so that you can change the propeller pitch in flight. The first adjustable-pitch propeller systems provided only two pitch settingsa low-pitch setting and a high-pitch setting. Today, however, nearly all adjustable-pitch propeller systems are capable of a range of pitch settings. Aconstant-speed propeller is the most common type of adjustable-pitch propeller. The main advantage of a constant-speed propeller is that it converts a high percentage of brake horsepower (BHP) into thrust horsepower (THP) over a wide range of r.p.m. and airspeed combinations. A constant-speed propeller is more efficient than other propellers because it allows selection of the most efficient engine r.p.m. for the given conditions. An airplane with a constant-speed propeller has two controls—the throttle and the propeller control. The throttle controls power output, and the propeller control regulates engine r.p.m. and, in turn, propeller r.p.m., which is registered on the tachometer. Once a specific r.p.m. is selected, a governor automatically adjusts the propeller blade angle as necessary to maintain the selected r.p.m. For example, after setting the desired r.p.m. during cruising flight, an increase in airspeed or decrease in propeller load will cause the propeller blade angle to increase as necessary to maintain the selected r.p.m. A reduction in airspeed or increase in propeller load will cause the propeller blade angle to decrease. The range of possible blade angles for a constant-speed propeller is the propeller’s constant-speed range and is defined by the high and low pitch stops. As long as the propeller blade angle is within the constant-speed range and not against either pitch stop, a constant engine r.p.m. will be maintained. However, once the propeller blades contact a pitch stop, the engine r.p.m. will increase or decrease as appropriate, with changes in airspeed and propeller load. For example, once a specific r.p.m. has been selected, if aircraft speed decreases enough to rotate the propeller blades until they contact the low pitch stop, any further decrease in airspeed will cause engine r.p.m. to decrease the same way as if a fixed-pitch propeller were installed. The same holds true when an airplane equipped with a constant-speed propeller accelerates to a faster airspeed. As the aircraft accelerates, the propeller blade angle increases to maintain the selected r.p.m. until the high pitch stop is reached. Once this occurs, the blade angle cannot increase any further and engine r.p.m. increases. On airplanes that are equipped with a constant-speed propeller, power output is controlled by the throttle and indicated by a manifold pressure gauge. The gauge measures the absolute pressure of the fuel/air mixture inside the intake manifold and is more correctly a measure of manifold absolute pressure (MAP). At a constant r.p.m. and altitude, the amount of power produced is directly related to the fuel/air flow being delivered to the combustion chamber. As you increase the throttle setting, more fuel and air is flowing to the engine; therefore, MAP increases. When the engine is not running, the manifold pressure gauge indicates ambient air pressure (i.e., 29.92 in. Hg). When the engine is started, the manifold pressure indication will decrease to a value less than ambient pressure (i.e., idle at 12 in. Hg). Correspondingly, engine failure or power loss is indicated on the manifold gauge as an increase in manifold pressure to a value corresponding to the ambient air pressure at the altitude where the failure occurred. [Figure 5-6] The manifold pressure gauge is color-coded to indicate the engine’s operating range. The face of the manifold pressure gauge contains a green arc to show the normal operating range, and a red radial line to indicate the upper limit of manifold pressure. For any given r.p.m., there is a manifold pressure that should not be exceeded. If manifold pressure is excessive for a given r.p.m., the pressure within the cylinders could be exceeded, thus placing undue stress on the cylinders. If repeated too frequently, this stress could weaken the cylinder components, and eventually cause engine failure. Manifold Absolute Pressure (MAP)—The absolute pressure of the fuel/air mixture within the intake manifold, usually indicated in inches of mercury. ch 05.qxd 10/24/03 6:50 AM Page 5-4 You can avoid conditions that could overstress the cylinders by being constantly aware of the r.p.m., especially when increasing the manifold pressure. Conform to the manufacturer’s recommendations for power settings of a particular engine so as to maintain the proper relationship between manifold pressure and r.p.m. When both manifold pressure and r.p.m. need to be changed, avoid engine overstress by making power adjustments in the proper order: • When power settings are being decreased, reduce manifold pressure before reducing r.p.m. If r.p.m. is reduced before manifold pressure, manifold pressure will automatically increase and possibly exceed the manufacturer’s tolerances. • When power settings are being increased, reverse the order—increase r.p.m. first, then manifold pressure. • To prevent damage to radial engines, operating time at maximum r.p.m. and manifold pressure must be held to a minimum, and operation at maximum r.p.m. and low manifold pressure must be avoided. Under normal operating conditions, the most severe wear, fatigue, and damage to high performance reciprocating engines occurs at high r.p.m. and low manifold pressure.
|
|
#3
12-17-2007, 05:33 AM
|
|||
|
|||
|
Could of done without the huge copy and paste, thanks all the same though. lol I've got the books and the FAA certificate.
 I'm just trying to clarify what Rama is saying so we can get on the same page.
|
|
#5
12-17-2007, 01:55 PM
|
|||
|
|||
|
ok guyz, to help you all with PP settings as they relate TO THIS GAME, is this:
Automatic props ( german, british ) don't worry about them. CSP equipped planes ( USA, USSR, Japan ): Take off: Full throttle 110%/ PP= 100% Ballz-to-the-wall full on speed run: Full throttle/ PP=95-90% why 95 to 90? try this: take a p38L late and go full throttle and fly as fast as you can on the deck....the plane hits a brickwall at about 470kph IAS and refuses to go any faster. Now keeping full throttle, adjust your prop pitch to 95-90% and watch your speed jump to about 570kph IAS. Dogfight: Full throttle 110%/ PP=100% Since dogfighting takes place at slower speeds ~300kph and lower....you'll need max power and ur prop blades grabbing the most air as possible to keep you from stalling at high angles of attack. Cruise: throttle 50-60%, PP=60% . A good rule of thumb that I go by when cruising is if I throttle back power to say...50%...I also pull my pp lever to nearly 50%. Keep ur throttle and pp levers on same % and you'll be doing good. Dives: Throttle back and pp back to nearly 50%. The game's aircraft dive rate is incredible and they all pick up speed very fast...no need to overwork ur motor by keeping it at 100 throttle and pitch..this actually hinders ur initial dive rate. Pull ur prop pitch back during a dive and you'll dive like the devil @!!@ AND THAT'S ALL YOU NEED TO KNOW ABOUT PROP PITCH IN THIS GAME. Last edited by Ironman69; 12-17-2007 at 01:58 PM.
|
|
#6
12-17-2007, 02:03 PM
|
|||
|
|||
|
Agree with all Ironman.
I could also add (also strictly for IL2): - if your engine is damaged, reduce PP, it will last longer - if you're low fuel, reduce PP to 0%-5%, your engine will heat, but you will save maybe enough fuel to reach base (against, it's IL2.. real thing is different) In fact, all planes in IL2 are equiped with CSP, except a few with fixed pitch (TB3, Gladiator, CR42, maybe a few others...) There are also those with fully atomatized CEM, like: - Bf109/Bf110 (if auto is off, then pitch is fully manual... don't use it without strong experience) - FW190 (if auto is off, then pitch is CSP controlled)
|
|
#7
12-17-2007, 08:57 PM
|
|||
|
|||
|
This is always a source of confusion for many reasons. First, there is many types of prop pitch setups in IL-2, as there were in the real planes. Second, people have a misconception about the idea of changing the pitch of a prop.
After reading the first page and a half, I just have to post and hopefully clear the air. First, adjustable pitch props are just like transmissions in a car. BUT, this is in the sense of ALLOWING the driver or pilot to set the engine RPM. In a race car, the transmission is geared to put the RPMs at or close to where the engine produces maximum power. In a sedan, the transmission is not geared the same way, and a balance between power and efficiency is made. When an engine is producing power, it doesn't do so linearly across the RPM and power output doesn't just keep going up with RPM. There is a curve where at low RPMs its producing a low amount of power, at higher RPM the engine will be producing more power; BUT at max RPM the engine MAY NOT be producing max power. However, power output is directly related to RPM. There is a POWER CURVE related to RPM. Since the above paragraph is true, you want some tool to allow the pilot to set the RPM of the engine. In combat situations, he would want to set the RPMs where ever the engine produces most power, at the peak of the power curve. In cross country situations, the pilot would favor efficiency over power output so he may set the engine RPMs lower than peak so to save on fuel and engine life. There are a handful of types of adjustable props in the game. The best is a CONSTANT SPEED PROP. This term is misleading as it really dictates the speed of the engine, not the speed of the prop. This type is found mostly on the US birds such as the P51. What happens is the pilot finds the RPM he wants to use (ie 2500) and sets the pitch to keep the engine @ 2500 rpms. The neat part now is, no matter what throttle settings he uses the governor will dynamically adjust the pitch of the prop so the engine maintains a constant speed of 2500 RPM. Now, at really power settings, the engine just can't produce enough power and the governor is set to NOT go to a 0° propeller AoA, so the RPMs will drop at low settings. The big payoff with this system, is the RPMs will be constant at all airspeeds, without intervention from the pilot. The next type of adjustable pitch propeller is just that; The Adjustable Pitch Propeller or Variable Pitch Propeller. The german fighters are built like this, IN GENERAL! (I say in general because 190 & 109 prop systems are similar they are really different) In this system, the pilot has direct control over the pitch of the prop. But again, the pilot would want to set the pitch to dictate the engine RPM's for he given situation. BUT... BUT... BUT... He must constantly change the pitch as his airspeed changes. In a climb, he has to apply a finer setting (closer to 100%), in a dive he has to apply a coarser setting (closer to 0%). Else in the former case he'll stall out or in the latter burn his engine up due to the high RPMs. Even straight and level flight needs attention as generally the airspeed increases so therefore you must use a coarser setting to maintain the same RPMs. In this system the RPMs will change also with throttle setting. Its a relationship between throttle, pitch setting and air speed; if any of these change, so does the RPMs. Therefore the pilot must constantly manually change the pitch setting. NOTE: 100% PITCH DOES NOT EQUAL 100% POWER AT ANY THROTTLE SETTING! More RPMs does not mean go faster. It's all about setting the engine to the RPM at which it produces the maximum power for any throttle setting*. *Even if the throttle isn't @ 100% or above, the engine still has a power curve, it's peak is the same RPM at max power, but it's just not putting out max power. Note: 190 is NOT a Constant Speed Propeller. Petition to get power curves published! Last edited by II./JG1_Krupinski; 12-17-2007 at 09:19 PM.
|
|
#8
12-18-2007, 12:53 PM
|
|||
|
|||
|
Quote:
not on my PC.............. i easily hit 570km/h TAS at SL with 100% pitch , not sign of any "wall" at 470. than when reducing the pitch to ~90%, i get slower. i'm am using that summary when flying IL2 concerning the pitch: for all piston engined planes except: Ki-27 J8A TB-3s Fw190 in auto mode Ta152H in auto mode Spitfire IX and VIII in auto mode Bf109, Bf110,Do335,Ta152C in manual and auto mode: the prop pitch in game is controlling the engine revolutions - so 100% pitch here means you allow the egnine to run at max rpm if enough throttle/power is available. in combat you shoud fly always with 100%. to lower your pitch is actually only necesarry if you want realy fly slow (that your comrades or the AI can close formation or you want safe fuel) , than you have to reduce the pitch like the throttle. same % rate or pitch 10% more than the throttle % is a good solution. also using full throttle and useing only 90-95% pitch can reduce the overheat chance - usefull in some planes like the Tempest or the Corsair and Hellcat. that doesnt harm your speed/climb much, if at all ! very few planes in game are overrev in a power dive (full power, 100% pitch) - IIRC that are the Cr.42, G.50, Mc.200, Fw190A/F in manual mode, Fw190D/Ta152H in manual mode, the Brewsters(not sure about that , may have changed in a patch) Fw190 in auto mode Spitfire IX and VIII in auto mode Bf109, Bf110,Do335,Ta152C in auto mode: have a one lever system, if you control the throttle, the pitch is automaticly also controled Bf109, Bf110,Do335,Ta152C in manual mode: thats totaly different, here you control the propeller blade angle direclty ! no automatic will keep the rpm in a "good" condition. it brings you no benefit to use this manual settings anymore (there was a time ). so, dont bother it the Ki-27 J8A TB-3s: have fixed propellers, so nothing to control there sure, others may have other experiences - but it fits for me.
|
|
#9
12-18-2007, 02:30 PM
|
|||
|
|||
|
Quote:
|
|
#10
12-17-2007, 01:47 PM
|
|||
|
|||
|
Quote:
You can see the contradiction with the first sentence? You can also look at the text quoted by Loco-S.... especially this part: Quote:
|
|
|
|
Hybrid Mode
