Darkrookie Posted July 2 Posted July 2 (edited) Hey all, Did some testing of level speeds in the Corsair and wanted to share the results, some tips I've found, and pose a question on the flight model at altitude. First, it's been floating around the forums and Youtube that you can "fix" the RPM "issue" on the engine and get more power by using your mouse to increase engine RPM past 2,700. This is a BUG. Max operating RPM for level flight with the Corsair (and the P-47) is 2,700 RPM. During a dive, RPM up to 3,050 is allowed for up to 30 second only. The ability reach this RPM during level flight is a BUG and hopefully will be fixed soon. According to what I've seen and read, the F4U-1D with the R2800-8W engine should reach 310-312 KTAS (356-359 MPH) at Sea Level in the following condition: 11,500 lbs Clean configuration WEP power (57.5" Hg and 2,700 RPM) Cowl, Intercooler, Oil Flaps closed Trimmed and Level flight and here's the one I think people miss a lot...AUTO LEAN mixture The Corsair in DCS does in fact reach 310-312 KIAS at Sea Level so we're good there. If you're coming from the P-47 like I am, it's counterintuitive to run full power in Auto Lean but that's per the manual and does give 10-12 knots more airspeed at Sea Level. If you're only hitting 299 KTAS check if you're in auto rich by mistake. If you're not even hitting that, you may have cowl/oil flaps open or not be trimmed in the yaw axis (side-slipping). Also make sure your throttle axis is allowing full travel of the throttle level (into the detent that activates the water injection) However...at 20,000 feet I wonder if there's a bug in the Flight/Engine model somewhere. It should reach 362-369 KTAS, (417-425 MPG) TRUE airspeed at 20,000 feet which is the critical altitude for the high supercharger setting (Note that I've also seen reports of 446 mph at 23,400 feet but I think that's the -4 model only). At 20,000 feet at WEP power (59.5" Hg and 2,700 RPM) I'm only reaching 327 KTAS, (376 True MPH) at an indicated airspeed of 220 knots. At the very least this is 35 knots or 40 MPH slow. Does anyone have results in DCS at altitude showing historical top speeds for the Corsair? If so, how did you achieve it? Thanks, Darkrookie Edited July 2 by Darkrookie typo
Hayrake YE-ZB Posted July 2 Posted July 2 Add one more parameter to make it an apples to apples comparison to the flight manual numbers- please set the temperature to 15ºC at SL in the mission editor. Unless listed, flight manuals use standard day temp/press for performance. Some posts have made the mistake of using SL temperature in the mission editor instead of the actual temperature aloft in their calculators. The static air temperature will decrease by 2ºC per 1000 feet of altitude increase. In your example, the OAT at 20000 would be -25C.
Darkrookie Posted July 2 Author Posted July 2 SL temp was 20 degrees C on the Marianas WWII map. I'll redo the test at 15C as suggested. For data recording, I took my true airspeed in knots straight from the F10 map though so that should account for any errors in conversion from IAS to CAS to TAS. I'll still test again and correct for temp change at altitude. 1
Saxman Posted July 2 Posted July 2 2 hours ago, Darkrookie said: Hey all, Did some testing of level speeds in the Corsair and wanted to share the results, some tips I've found, and pose a question on the flight model at altitude. First, it's been floating around the forums and Youtube that you can "fix" the RPM "issue" on the engine and get more power by using your mouse to increase engine RPM past 2,700. This is a BUG. Max operating RPM for level flight with the Corsair (and the P-47) is 2,700 RPM. During a dive, RPM up to 3,050 is allowed for up to 30 second only. The ability reach this RPM during level flight is a BUG and hopefully will be fixed soon. According to what I've seen and read, the F4U-1D with the R2800-8W engine should reach 310-312 KTAS (356-359 MPH) at Sea Level in the following condition: 11,500 lbs Clean configuration WEP power (57.5" Hg and 2,700 RPM) Cowl, Intercooler, Oil Flaps closed Trimmed and Level flight and here's the one I think people miss a lot...AUTO LEAN mixture The Corsair in DCS does in fact reach 310-312 KIAS at Sea Level so we're good there. If you're coming from the P-47 like I am, it's counterintuitive to run full power in Auto Lean but that's per the manual and does give 10-12 knots more airspeed at Sea Level. If you're only hitting 299 KTAS check if you're in auto rich by mistake. If you're not even hitting that, you may have cowl/oil flaps open or not be trimmed in the yaw axis (side-slipping). Also make sure your throttle axis is allowing full travel of the throttle level (into the detent that activates the water injection) However...at 20,000 feet I wonder if there's a bug in the Flight/Engine model somewhere. It should reach 362-369 KTAS, (417-425 MPG) TRUE airspeed at 20,000 feet which is the critical altitude for the high supercharger setting (Note that I've also seen reports of 446 mph at 23,400 feet but I think that's the -4 model only). At 20,000 feet at WEP power (59.5" Hg and 2,700 RPM) I'm only reaching 327 KTAS, (376 True MPH) at an indicated airspeed of 220 knots. At the very least this is 35 knots or 40 MPH slow. Does anyone have results in DCS at altitude showing historical top speeds for the Corsair? If so, how did you achieve it? Thanks, Darkrookie F4U-1D should be +/-410mph TAS at critical altitude. The 420mph figure is for an F4U-1A with water injection. The 1D loses about 10mph due to drag from the knuckle pylons.
MIDWAY Posted July 2 Posted July 2 I'm not getting any difference at sea level with auto rich or auto lean. Care to post a track showing the difference on your end?
Art-J Posted July 3 Posted July 3 17 hours ago, Hayrake YE-ZB said: Add one more parameter to make it an apples to apples comparison to the flight manual numbers- please set the temperature to 15ºC at SL in the mission editor. Unless listed, flight manuals use standard day temp/press for performance. Do they always, though? ISA was universally adopted in 1970s, older US atmosphere models were standardized in 1950s. When reading test reports from 1940s SL temperature sometimes becomes yet another annoying variable then. i7 9700K @ stock speed, single GTX1070, 32 gigs of RAM, TH Warthog, MFG Crosswind, Win10.
Dkha Posted July 3 Posted July 3 19 hours ago, Darkrookie said: and here's the one I think people miss a lot...AUTO LEAN mixture Funny enough, I ran some tests at 6,000 feet with the exact same configuration and I was actually FASTER with the mixture set to Auto Rich hahahaha. I reached 275 KIAS (according to the DCS gauge). I went looking for an explanation and saw people commenting that: MIXTURE CONTROL. - Auto Lean is used for cruising power settings below approximately 35 inches of manifold pressure. Auto Rich is required for all other power settings including take-off, climb, and combat. I know it’s not listed that way in the manual. It just says to keep it in Auto Lean for pretty much the entire flight, but I honestly felt a real difference in speed when set to Auto Rich under my conditions. =P
Darkrookie Posted July 3 Author Posted July 3 1 minute ago, Dkha said: Funny enough, I ran some tests at 6,000 feet with the exact same configuration and I was actually FASTER with the mixture set to Auto Rich hahahaha. I reached 275 KIAS (according to the DCS gauge). I went looking for an explanation and saw people commenting that: MIXTURE CONTROL. - Auto Lean is used for cruising power settings below approximately 35 inches of manifold pressure. Auto Rich is required for all other power settings including take-off, climb, and combat. I know it’s not listed that way in the manual. It just says to keep it in Auto Lean for pretty much the entire flight, but I honestly felt a real difference in speed when set to Auto Rich under my conditions. =P Seems people are getting mixed results then. Though there are a lot of variables that can skew things...trim, flying coordinated, temperature, engine settings etc. I'll keep testing in particular for air temperature and if auto rich and auto lean really make a difference. When I did my first few tests I couldn't get past 299 kn (on the DCS f10 screen) until I put it in auto-lean. Once in auto-lean I got 312. I didn't test it at other power settings or altitudes though. 17 hours ago, Saxman said: F4U-1D should be +/-410mph TAS at critical altitude. The 420mph figure is for an F4U-1A with water injection. The 1D loses about 10mph due to drag from the knuckle pylons. Noted, thanks! Still, my speed at 20K feet was far lower than even 410 mph true.
Saxman Posted July 3 Posted July 3 6 minutes ago, Dkha said: I know it’s not listed that way in the manual. It actually is, depending on which version of the manual you're talking about. Some editions include charts for both the -8 (using Auto Rich on WEP, MIL, and Normal) and -8W (Auto Lean for all but takeoff).
Dkha Posted July 3 Posted July 3 (edited) 42 minutes ago, Saxman said: Some editions include charts for both the -8 (using Auto Rich on WEP, MIL, and Normal) and -8W (Auto Lean for all but takeoff). So the F4U we have is the version without water injection? hahaha I went looking through other manuals and found one for the FG-1D for FSX made by MILVIZ. In it (the manual) it has the same information as the original manual, of course, but it's listed as a -8 (without the W). And look how funny: This really makes me think the engine we have is actually wrong hahahaha. It seems like they literally took the FG-1D’s FM of FSX, dropped it into DCS, and called it the F4U-1D. Considering both were supposed to have the Pratt & Whitney R-2800-8W, but in FSX it came with the Pratt & Whitney R-2800-8 To me it’s literally like they just took the FM from FSX (which should have had water injection), brought it over to DCS, and just changed the name and the skins… Because in both games the engine is the same… The wrong one. Edited July 3 by Dkha 1
Saxman Posted July 3 Posted July 3 It's honestly hard to tell, because the mechanism for water injection IS also modeled (at the very least you can activate it and the 3-minute warning light will come on, and some people report gaining a couple kts of airspeed, though by far not enough). 1
Dkha Posted July 3 Posted July 3 For me it went like this: with the settings I mentioned, keeping it in Auto Rich, I reached 275 KIAS. When I used water injection, I got up to 286 KIAS, but it took a while to reach that speed. 1
Saxman Posted July 4 Posted July 4 So tonight I went up earlier to do some testing on the blow-up flaps, but also spent some time doing some speed testing. At 22,000ft, trimmed for level flight, cowl flaps, oil cooler, and supercharger closed, full throttle, WEP switch to "on." I managed to JUST get to 250kts IAS. With a surface temperature of 28 degrees C and a calculated -15 degrees at altitude, that gives me a TAS of 364kts, about 418mph. That's a little faster than the F4U-1D is supposed to be. I didn't notice any real difference in speed between Auto Lean and Auto Rich. 1
Darkrookie Posted July 4 Author Posted July 4 1 hour ago, Saxman said: So tonight I went up earlier to do some testing on the blow-up flaps, but also spent some time doing some speed testing. At 22,000ft, trimmed for level flight, cowl flaps, oil cooler, and supercharger closed, full throttle, WEP switch to "on." I managed to JUST get to 250kts IAS. With a surface temperature of 28 degrees C and a calculated -15 degrees at altitude, that gives me a TAS of 364kts, about 418mph. That's a little faster than the F4U-1D is supposed to be. I didn't notice any real difference in speed between Auto Lean and Auto Rich. Thanks for this! I'll run another test tonight as well and see if we can replicate.
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