Engine Power/Aircraft Speed

[Templar560]

I've been flying with some friends and there seems to be strange power issues going. In a hot start aircraft nd in a cold start we weren't getting more than 170mph. In the instant action free flight the Corsair is doing 260 mph. Nothing we did in multiplayer seemed to help us speed up. Not seen any other mention of this so maybe it's something we've collectively done/not done?

 

 

 

[felixx75]

21 minutes ago, Templar560 said:

I've been flying with some friends and there seems to be strange power issues going. In a hot start aircraft nd in a cold start we weren't getting more than 170mph. In the instant action free flight the Corsair is doing 260 mph. Nothing we did in multiplayer seemed to help us speed up. Not seen any other mention of this so maybe it's something we've collectively done/not done?

 

 

 

I haven't had that problem so far...

btw. in contrast to the P-47 or P-51, the F4U displays knots and not mph 

[Templar560]

The knots versus mph isn't relevant to this issue but yes good to know.

[Kovacs]

Interesting, I was wondering about the speed too, including when diving. 

I'm going to do more tests, but I feel like I'm going much slower than with the P-51. Strange. I'll try in instant action to compare. 

[felixx75]

The P-51D IS faster than a F4U-1D. So your feelings are correct.

[Templar560]

Kovacs thanks let me know!

 

[Kovacs]

1 hour ago, felixx75 said:

The P-51D IS faster than a F4U-1D. So your feelings are correct.

Thanks, yes you're right 425 mph vs 440 mph.  I'm going to do some tests using the documentation.

[Firebugs]

At sea level in level flight at full mil power I'm getting 295-300kts which from the information I could find I believe is correct.  However, we should be able to get another 15-16kts with water injection and I haven't been able to get that to work yet. 

[Templar560]

5 hours ago, Firebugs said:

At sea level in level flight at full mil power I'm getting 295-300kts which from the information I could find I believe is correct.  However, we should be able to get another 15-16kts with water injection and I haven't been able to get that to work yet. 

That's interesting as we were only getting 180. What settings were you flying with?

[Nealius]

180 sounds like you had some drag hanging out. 29C day, Gear up, flaps up, intercooler closed, oil coolers 1/2 to 1/3 open, cowl flaps maybe 1/4 open, 2550rpm 43" and I was easily doing 210kts indicated just cruising around below 1,000ft. 

[G_Air]

Same here, I have not been able to pull more than 220 kts at level flight at cruise clean configuration, even with cowls, oil and inner cooler flaps closed. RPM and Man at max, all flaps closed wont get pass 250 kts, at cruise, 2550 RPM and 48, a little over 210.... I tried different mixture and blower settings but nothing improve the power... It seems very slow when compared with the mustang or jug, which at cruise at sea level go above 300 kts

[Convoy]

Same, can't get her above 250, low or high altitude 

[Mike Busutil]

Level 20,000' msl 

Clean. (Flaps up / gear up / cowl, oil & intercooler flaps closed / no external stores)

2700 rpm

61 inHg

Blower High

Auto rich

I was able to get 242 knots IAS, (352 knots true) which is only 278.489 mph. 

[Gunfreak]

6 hours ago, Mike Busutil said:

Level 20,000' msl 

Clean. (Flaps up / gear up / cowl, oil & intercooler flaps closed / no external stores)

2700 rpm

61 inHg

Blower High

Auto rich

I was able to get 242 knots IAS, (352 knots true) which is only 278.489 mph. 

Try auto lean. Apparently they never used auto rich outside of take off and landing. As lean gave better preformance even in combat.(according to Reflectedes video) 

[Spurts]

352KTAS is 405mph.

[Mike Busutil]

56 minutes ago, Gunfreak said:

Try auto lean. Apparently they never used auto rich outside of take off and landing. As lean gave better preformance even in combat.(according to Reflectedes video) 

For the F4U-1D Corsair to achieve its maximum airspeed of approximately 425 mph at 20,000 ft (critical altitude, with full throttle, ~54 inches Hg manifold pressure, 2,700 RPM, cowl flaps closed, gear/flaps up, high blower engaged), the optimal mixture setting is Auto Rich. Here’s why:

1. Auto Rich for Maximum Power:
   • Function: The F4U-1D’s Pratt & Whitney R-2800-8W engine uses an automatic mixture control system with settings like “Auto Rich” and “Auto Lean.” Auto Rich delivers a richer fuel-air mixture (higher fuel-to-air ratio), optimizing combustion for maximum power output during high-performance operations like full throttle for max speed.
   • Performance Impact: At full power (~2,000–2,200 hp with water injection), Auto Rich ensures the engine produces maximum horsepower by providing sufficient fuel to prevent detonation and maintain cylinder cooling, critical for achieving ~425 mph at 20,000 ft.
   • Historical Context: Navy pilot manuals (e.g., AN 01-45HB-1) specify Auto Rich for takeoff, climb, and high-speed flight, as it supports the high manifold pressure (~54 inches Hg) and RPM (2,700) needed for max speed.
   • Auto Lean for Efficiency, Not Max Speed:
   • Function: Auto Lean reduces the fuel-to-air ratio for fuel efficiency during cruise or low-power operations (e.g., ~25 inches Hg, 1,800 RPM for max range, ~1,015–2,200 miles). It’s unsuitable for max speed because it limits power output, reducing thrust and speed.
   • Performance Impact: Using Auto Lean at full throttle would cause the engine to run too lean, risking detonation, overheating, or power loss, potentially dropping speed by ~20–50 mph (e.g., to ~375–400 mph at 20,000 ft, based on estimated power reduction).
   • Altitude Consideration: Above 20,000 ft (e.g., 30,000 ft, where speed drops to ~410 mph), Auto Lean might be used briefly to optimize fuel burn if cruising, but Auto Rich remains standard for max speed to maintain power in thinner air with the high blower engaged.

   • Sources: The recommendation of Auto Rich for max speed is based on F4U-1D pilot manuals (e.g., AN 01-45HB-1), which specify Auto Rich for high-power settings (takeoff, combat, max speed). WWII radial-engine fighter practices (e.g., F6F Hellcat) confirm rich mixtures for maximum performance.

2. F4U-1D Top Speed vs. Mixture Setting (20,000 ft)
   ================================================
   Auto Rich (425 mph)     |█████████████████████ 425
   Auto Lean (~390 mph)    |███████████████████ 390
   Manual Lean (~360 mph)  |█████████████████ 360
   ================================================
   (Each █ ≈ 20 mph)

[Gunfreak]

35 minutes ago, Mike Busutil said:

For the F4U-1D Corsair to achieve its maximum airspeed of approximately 425 mph at 20,000 ft (critical altitude, with full throttle, ~54 inches Hg manifold pressure, 2,700 RPM, cowl flaps closed, gear/flaps up, high blower engaged), the optimal mixture setting is Auto Rich. Here’s why:

1. Auto Rich for Maximum Power:
   • Function: The F4U-1D’s Pratt & Whitney R-2800-8W engine uses an automatic mixture control system with settings like “Auto Rich” and “Auto Lean.” Auto Rich delivers a richer fuel-air mixture (higher fuel-to-air ratio), optimizing combustion for maximum power output during high-performance operations like full throttle for max speed.
   • Performance Impact: At full power (~2,000–2,200 hp with water injection), Auto Rich ensures the engine produces maximum horsepower by providing sufficient fuel to prevent detonation and maintain cylinder cooling, critical for achieving ~425 mph at 20,000 ft.
   • Historical Context: Navy pilot manuals (e.g., AN 01-45HB-1) specify Auto Rich for takeoff, climb, and high-speed flight, as it supports the high manifold pressure (~54 inches Hg) and RPM (2,700) needed for max speed.
   • Auto Lean for Efficiency, Not Max Speed:
   • Function: Auto Lean reduces the fuel-to-air ratio for fuel efficiency during cruise or low-power operations (e.g., ~25 inches Hg, 1,800 RPM for max range, ~1,015–2,200 miles). It’s unsuitable for max speed because it limits power output, reducing thrust and speed.
   • Performance Impact: Using Auto Lean at full throttle would cause the engine to run too lean, risking detonation, overheating, or power loss, potentially dropping speed by ~20–50 mph (e.g., to ~375–400 mph at 20,000 ft, based on estimated power reduction).
   • Altitude Consideration: Above 20,000 ft (e.g., 30,000 ft, where speed drops to ~410 mph), Auto Lean might be used briefly to optimize fuel burn if cruising, but Auto Rich remains standard for max speed to maintain power in thinner air with the high blower engaged.

   • Sources: The recommendation of Auto Rich for max speed is based on F4U-1D pilot manuals (e.g., AN 01-45HB-1), which specify Auto Rich for high-power settings (takeoff, combat, max speed). WWII radial-engine fighter practices (e.g., F6F Hellcat) confirm rich mixtures for maximum performance.

2. F4U-1D Top Speed vs. Mixture Setting (20,000 ft)
   ================================================
   Auto Rich (425 mph)     |█████████████████████ 425
   Auto Lean (~390 mph)    |███████████████████ 390
   Manual Lean (~360 mph)  |█████████████████ 360
   ================================================
   (Each █ ≈ 20 mph)

Again. Not according to reflected 

From 11:11

 

[Nealius]

I trust Reflected and his sources more than I trust a copy-pasted ChatGPT "answer."

[Mike Busutil]

I guess you missed this part...

• Sources: The recommendation of Auto Rich for max speed is based on F4U-1D pilot manuals (e.g., AN 01-45HB-1), which specify Auto Rich for high-power settings (takeoff, combat, max speed). WWII radial-engine fighter practices (e.g., F6F Hellcat) confirm rich mixtures for maximum performance.

Go back to watching Youtubers tell you how its done. 

[Gunfreak]

14 minutes ago, Mike Busutil said:

I guess you missed this part...

• Sources: The recommendation of Auto Rich for max speed is based on F4U-1D pilot manuals (e.g., AN 01-45HB-1), which specify Auto Rich for high-power settings (takeoff, combat, max speed). WWII radial-engine fighter practices (e.g., F6F Hellcat) confirm rich mixtures for maximum performance.

Go back to watching Youtubers tell you how its done. 

You do know there's a difference between manuals and real life?

In many cases sims follows manuals too much. Like taking the engine limitations in the manual as a hard limit. Instead of what they are recommendations for maximum service life of the engine. Which isn't really valid when the ground crew would often just pull out an over-used and swap it. (At least in ETO, less so in PTO) Real pilots didn't think about 5 or 10 minutes WEP limits. They would go full power however long it was needed. And the aircraft would get them home.  If prolonged WEP had been used the engine would get a though going through.  Or even just swapped. Sim engines are way to snow flakey. But "half the fun" of ww2 flight sim is the engine management. And sim pilotpilots would find it unrealistic if the engine didn't die after 5 minutes of WEP.

[EnzoF98]

20 minutes ago, Mike Busutil said:

I guess you missed this part...

• Sources: The recommendation of Auto Rich for max speed is based on F4U-1D pilot manuals (e.g., AN 01-45HB-1), which specify Auto Rich for high-power settings (takeoff, combat, max speed). WWII radial-engine fighter practices (e.g., F6F Hellcat) confirm rich mixtures for maximum performance.

Go back to watching Youtubers tell you how its done. 

I guess you (and ChatGPT) missed this part: 

 

AN 01-45HA-1, for the F4U-1D, shows Auto Lean for all but take-off.

Edited Monday at 01:37 PM by EnzoF98

[Mike Busutil]

6 minutes ago, EnzoF98 said:

AN 01-45HA-1, for the F4U-1D, shows Auto Lean for all but take-off.

 

Good catch. But it looks like the top speed in auto lean still falls short of the expected max speed at 20,000 msl.

[Nealius]

37 minutes ago, EnzoF98 said:

I guess you (and ChatGPT) missed this part: 

This is a good example of why AI can't be trusted. If you have to cross-check the sources after asking AI anyway you might as well go and hunt for the correct sources directly and skip the AI entirely. The R2800-18W in the F4U-4 looks almost like a completely different engine compared to the F4U-1's -8W but I'm no engine expert and I'm just going off the Wikipedia description. Certainly not the same engine between the two airframes despite having the same base designation.

Edited Monday at 02:14 PM by Nealius

[felixx75]

I also know the manual for the Corsair (AN 01-45HA-1), but I have found the same table twice, but with different contents. On the pictures you can see the known table, but on the one picture “Auto-Lean” is listed everywhere except for the TO, but on the other one “Auto Lean” is only listed for “Max. cruise” and “Min. fuel burn”. Both from the same manual. The question now arises as to which is correct...

 

 

Edited Monday at 03:12 PM by felixx75

[Mike Busutil]

1 hour ago, felixx75 said:

I also know the manual for the Corsair (AN 01-45HA-1), but I have found the same table twice, but with different contents. On the pictures you can see the known table, but on the one picture “Auto-Lean” is listed everywhere except for the TO, but on the other one “Auto Lean” is only listed for “Max. cruise” and “Min. fuel burn”. Both from the same manual. The question now arises as to which is correct...

 

 

Thanks, this is what I was seeing as well.