Is RPM actually modeled properly outside of changing the RPM gauge? Does it affect the flight performance? Where do you guys research information about the plane when you created it? The RPM can go up to 2600 in the game but sources online say that the P-38s engines reach max torque at 3000 RPM and later models at 3400. Is there a reason that the P-38 in the game can’t go up to even 3000? Do you have information about it that suggests it can only go up to 2600? Does it not go higher because the superchargers for it aren’t modeled yet? I’ve read on this forum that the P-38 supercharger isn’t modeled so maybe this is why the RPM only goes to 2600. I also wonder if this is why the P-38 can’t cruise above 300 knots when it was always known to cruise at 350. In addition it can hardly climb above 160 knots when it should easily climb at 180-200 knots based on what I know about it. Again is this because the supercharger is not modeled or just because different stats were given to it in the game?
What RPM produces the highest torque in the P-38 L-5
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Each piston engine has a torque vs. RPM curve in Aerofly FS so yes that is modeled.
Highest torque is not something displayed to the pilots nor is the actual power of the engine which is torque multiplied by rotation speed. The best measure for the power output in the manifold pressure. And because no supercharger or turbocharger is currently modeled the pressure never goes above atmospheric pressure as it would with super- or turbochargers.
The rotation speed is adjusted by the prop governor. It adjusts the pitch of the propeller blades to maintain 2600 RPM in our engine. I'm not sure if there were many different engine versions installed over time, we may have a different one with only 2600 RPM? I would need to look through the documentation again, don't have it here right now unfortunately.
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Almost all multi stage, multi speed supercharger and turbo supercharger aircraft post war had their boosting equipment simplified or reduced to a minimal state in order to reduce operating costs and to increase reliability. The American turbo equipped planes were often left with just the integrated single speed and stage supercharger at the rear of the engine which in the case of P-38s left them in a condition comparable to the P-39 and Allison equipped P-40 both of which only ever had the performance limiting single stage single speed supercharger. Those integrated superchargers were as much for even charge delivery and ground level power increase as any serious high altitude capability.
A simulation of a privately owned P-38 operating in the airshow circuit and never needing to fly really high might well only ever show manifold pressures with a few pounds of boost, perhaps equivalent to a sea level manifold pressure of about 35 inches of mercury. Put that plane on the ground at Denver and it would never exceed 30" on the manifold gauges.
The Aerofly P-38 is not that far off a modern day privately owned example. I’m happy enough with the engine performance.
(If it can get some work done then better roll stability at 100 mph would tame the excessively unpredictable landings).Back to torque, it has constant speed propellers so a high rpm with fine pitch on the propellers will create less torque than a certain lower rpm with coarse pitch. The manifold pressure and the fuel flow must be evaluated too.
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If we are talking about L5 version of the plane, they had V-1710-112/113 (F30R/L) engines.
""F" series engines were designed for late model pursuit aircraft, and are identified by the compact external spur gear-type reduction gear box. Military models were V-1710-27, -29, -39, -45, -49, -51, -53, -55, -57, -61, -75, -77, -81, -87, -89, -91, -95, -99, -101, -105, -107, -111, -113, -115, -119, producing 1,150–1,425 hp (858–1,063 kW) at 3000 rpm. The V-1710-101, -119 and -121 models has an auxiliary supercharger, some with a liquid-cooled aftercooler. Supercharger gear ratios were: 6.44:1, 7.48:1, 8.10:1, 8.80:1 and 9.60:1 depending on altitude rating. These engines had either a six or twelve weight crankshaft, revised vibration dampeners that combined to allow higher engine speeds, SAE #50 propeller shaft, and higher horsepower ratings. The "E" series and "F" series engines were very similar, the primary difference being the front crankcase cover, which was interchangeable between the two series engines"
Engine gear ratio also was different.
But yes, after the war their boosting equipment was "simplified" (in other planes like C-47 and countries like GB even removed). Also to prolong the life of their engines pilots today tend not to use more than 70% of their engines power (for Bf-109s, for example)
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Each piston engine has a torque vs. RPM curve in Aerofly FS so yes that is modeled.
Highest torque is not something displayed to the pilots nor is the actual power of the engine which is torque multiplied by rotation speed. The best measure for the power output in the manifold pressure. And because no supercharger or turbocharger is currently modeled the pressure never goes above atmospheric pressure as it would with super- or turbochargers.
The rotation speed is adjusted by the prop governor. It adjusts the pitch of the propeller blades to maintain 2600 RPM in our engine. I'm not sure if there were many different engine versions installed over time, we may have a different one with only 2600 RPM? I would need to look through the documentation again, don't have it here right now unfortunately.
I appreciate the explanation I’ll try referencing the manifold pressure as i experiment with different prop pitch settings. If that ends up just being 100% rpm and 100% throttle then that makes things simple. Especially because i dont think fuel consumption is modeled so there’s no need to be more efficient or fly with 1 prop.
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You can get 100% RPM with idle throttle tough, you just have to be fast enough for the propeller to windmill
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You can get 100% RPM with idle throttle tough, you just have to be fast enough for the propeller to windmill
Could you explain the relationship of how i use the RPM prop levers? Do different RPMs change how i accelerate or climb? Or are they supposed to affect my top speed? Ive tried cruising level flight at close to sea level and I have noticed the manifold pressure stays the same at different prop pitches it stays 30 inches. At close to top cruise speed at sea level i noticed i go just a couple of knots faster at 2500 rpm vs the max of 2600 rpm. On the other hand when i put the parking brake on and go max throttle and max RPM the governor lets my prop spin all the way up to 3000 RPM. Why can the prop go to higher rpms when I’m not moving or barely moving but decreases at higher speeds? Also When I’m starting from the ground at 100% throttle my manifold pressure is 36 inches of mercury at minimum RPM of 1200 and and at maximum RPM of 3000 i get 33 inches. I want to know how I should be changing the prop pitch levers to get the best performance in each stage of flight.
Okay so I just discovered that above like 1250 feet above sea level the max RPM starts to curve off from 3000 to 2600 so it happens really quickly. I didnt expect that. Ive done most of my flying in Arizona and phoenix is about 1500 feet already so flying out of catalina island and going down to 500 feet i noticed a much higher engine rpm and a high flat out cruise speed so that must be due to the lack of supercharging in the game.
After doing more research ive come to understand that when using a constant speed prop there is very little relationship between prop pitch and top speed. There is technically a pitch for “best cruise speed” and its slightly lower than the top rpm setting in the p38 but what changing the pitch mostly does is allow for better acceleration and climb power and more fuel efficient flight. Like the higher rpm your prop goes is like a lower gear on a bike you will gain altitude faster and probably accelerate faster from a low speed or stand still but youll be less fuel efficient. Allowing a coarser prop pitch or lower rpm setting grabs more air per the fuel you burn and increases engine efficiency.
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RPM is just how fast the propeller spins. The faster it spins the more air is available to push. With a constant speed propeller the prop governor tries to maintain the RPM set by the propeller speed levers. In Aerofly FS we also have an assistance for the engines which changes to cruise RPM after takeoff (which might explain the drop from 3000 to 2600RPM that you see). If you manually drag the propeller speed levers forward the assistance should turn off though until you're close to landing, where it tries to increase RPM to maximum again.
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Imagine that a constant speed propeller works like a speed controller. If you set a speed of 2600 rpm at a given mainflood pressure, it will change the pitch of the propeller until it reaches that rpm. If you give more throttle, the mainflood pressure and the rpm will increase. Therefore, the controller will increase the pitch of the propeller until the 2600 rpm is restored and the airplane will fly faster. If you take the throttle lower, the rpm will drop, the controller will set a smaller pitch, the speed will return to 2600 rpm, and you will fly slower. For takeoff and landing, the propeller should always be set to the minimum pitch because the engine is not loaded this way and accelerates better when the throttle is applied.
