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P-51A - Printable Version

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P-51A - -)-MAILMAN- - 24.09.2012

The next question I have is in regards to the P-51A. The P-51A has a 70 gallon port wing tank and a 60 gallon starboard wing tank and did not have the 85 gallon fuselage fuel tank behind the pilot. This is right out of the pilot notes of the Mustang I and Ia.

In the game the P-51A cockpit shows the left wing fuel capacity gage and the starboard wing fuel capacity gage and the 85 gallon fuselage tank gage behind the pilot. All three gages work because I tested the different fuel load outs and they moved as I changed the capacity lower and lower each time I spawned. If the 85 gallon is installed in the flight model it would explain its sluggishness.

Is this something that will be corrected in the future?


-)-MAILMAN-

Re: P-51A - aaken - 26.09.2012

Hi again, when I firstly worked on the P51s, if I rember correctly, there was no A version. Definitely I can look at it for one of the next mini-patches.
As for the 1650-7 of a previous post, the D20 and D20NT have been modeled with a -7 engine whereas the later D marks (D25 and D30) have been modeled with the -9.
Regards,
Aaken

Re: P-51A - -)-MAILMAN- - 26.09.2012

Thanks again for a such a quick reply. Indeed the P-51/Mustang I (Allison V-1710-F.3R), P-51A/Mustang IA (Allison V-1710-F.3R/M) and A-36A-1 (Allison V-1710-87) were not in the game when you worked on the P-51's.

The P-51A and Mustang IA were added and the other day I sent Monguse a copy of a page right out of the Mustang I and Mustang IA Pilot Manual. The diagram showed the two wing tanks and clearly no fuselage tank behind the pilot. It even depicted the ferry condition where the guns would be removed and auxiliary fuel tanks would replace them.

I imagine it would this would place the COG in a different location on the P-51A and would change the aircraft weight with a full load of fuel when compared with the P-51B & C & D.

Anything that leads to more accurate flight models is appreciated.


-)-MAILMAN-

Re: P-51A - aaken - 27.09.2012

As far as I can see, the flight model used for the A version is exactly the same as the one used for B version, except the engine.
I'll definitely look at the A version flight model next week. As far as the overheat for the Packard-Merlin versions is concerned, have you encountered issues you want me to look at?
Regards,
Aaken

Re: P-51A - -)-MAILMAN- - 27.09.2012

I have flown the P-51A probably a dozen times. Down low on the deck on the Burma map in the QMB it doesn't take too awfully long to start to overheat. I was surprised how long it took to overheat above 15,000 - 18,000 feet at 110% throttle.

I do have a .pdf of Air Publication 2025A Pilot Notes for the Mustang I and Mustang IA Aeroplane: Allison V-1710 F.3R Aero-Engine and Allison V-1710 F.3R/M Aero-Engine. It has not only the takeoff, climb, continuous and combat power values, but it has the associated max coolant temperatures and also the oil temperatures for each condition.

Now speaking of overheating I would like a question answered if you can.


Another question while looking at the engine performance data of the R-2800-8 and 8W I noticed that there were two different altitudes where the supercharger is switched from neutral to low blower. With NO RAM it is switched at 5000 feet, but with RAM it is switched at 7000 feet. Please explain to me what condition would represent NO RAM and what condition would represent RAM. An uneducated guess would be that NO RAM would be either sitting on the ground or while flying with cooling flaps/doors closed and RAM would be flying with cooling flaps/doors open.


I look forward to your explanations.


I hadn't been playing the game much because for so long the manifold pressure gage for the corsairs was messed up. Since they were fixed recently I started flying this sim again and had been testing out the new P-51A. I will start to fly the B & C for the next week when I can and see what happens with the heat.


-)-MAILMAN-

Re: P-51A - aaken - 28.09.2012

Hello again,

I do not remember the precise figure but typically I set the overheat parameters of the engine so as to get a maximum flying time at maximum emergency engine setting at SL of about 5 minutes with cooling flaps opened (with some variations around that figure depending on the engine).

As for the supercharger question, I do not remember the exact installation of the R2800-8 on the Corsair (I do remember that it was quite different from the P-47 installation) but the difference in air pressure associated to 2000 ft in altitude is coherent with a ram recovery pressure with and without flaps or louvres.

Aaken

Re: P-51A - -)-MAILMAN- - 28.09.2012

Well the P-47's had a turbo supercharger with their R-2800, but the Hellcats and Corsairs had manual two stage, two speed superchargers. The Hellcats had the R-2800-10 & 10W while the Corsairs had the R-2800-8 & R2800-8W.

Using the R-2800-8 of the Corsair as an example under the below Operating Conditions:

Sea Level
Take-Off Maximum Duration 5 minutes 2000HP 2700 RPM 54"Hg Auto Rich Neutral Blower Max Cylinder Head Temp is 260°c Max Oil Temperature 100°c
War Emergency Maximum Duration 5 minutes 2250 HP 2700 RPM 57.5"Hg Auto Rich Neutral Blower Max Cylinder Head Temp is 260°c Max Oil Temperature 100°c
Military Maximum Duration 5 minutes 2000HP 2700 RPM 52.5" Auto Rich Neutral Blower Max Cylinder Head Temp is 260°c Max Oil Temperature 100°c

Does the 5 minute duration start the moment we cross from normal rated continuous to one of the above conditions or from the time we start seeing the Overheat Message?

Does the engine damage occur after 5 minutes duration above normal rated continuous or 5 minutes after the overheat message?

Is there a specific time when the overheat message appears after crossing from normal rated continuous to one of the above conditions?


Critical Altitude
With RAM: What is RAM and how does it determine the critical altitude?
NO RAM: What is NO RAM and how does it determine the critical altitude?

Why is there a 2,000 foot difference between With RAM & NO RAM?

Thanks


-)-MAILMAN-

Re: P-51A - aaken - 29.09.2012

What I mean as engine installation is how the engine is installed and integrated in the fuselage. For instance the P-47 turbocompressor is installed in the aft section of the fuselage and connected to the air intake (which for the P-47 is a dynamic intake, as far as I remember) which lies in the lower lobe of the engine mount and completely immersed in the propwash. I do not remember precisely how this is done on the Corsair.

The engine regime limitation consists in the time you are allowed to run your engine at a specified rpm and manifold pressure (since indicated average pressure in the cylinders will depend on that). So the 5 minutes limit start, so to speak, when you start running at the rpms and manifold pressure indicated in the AFM.
The engine damage occurrs after exceeding engine regime time limit independently of overheat.
Of course exceeding prescribed maximum rpms and manifold pressure reduces the engine time limit.
This you see fairly clearly on fixed propeller pitch engines or in airplanes with damaged propeller pitch governor.
The overheat message does not appear after a fixed specified time. The Oil and Water outlet temperature variation law depends on engine setting, rad position and most importantly airplane speed (apart the obvious dependency on OAT).
I'll try to expand a bit on the RAM later.
regards,
Aaken

Re: P-51A - -)-MAILMAN- - 29.09.2012

Thanks for the detailed explanation. I am trying to find the limitations imposed on the various aircraft I fly. Guess I should invest in a stop watch. Smile

Now I know that the cowl flaps control in the game opens both the cowl flaps and the radiator/oil cooler flaps. On the real aircraft these could be operated independently. I created a mission using the Solomons October 1943 and I set the date of October 1, 1943. I took off from Barakoma in a F4U-1A Corsair and noted that after attaining the top level speed at the normal power condition of 44" MAP.2550 RPM I went to War Emergency Power (110% Water Injection and 2700 RPM) with the cowl flaps/radiator closed the first temperature to reach its limit was the oil. If I could have opened just the intercooler flaps independently I could have delayed this for a brief period of time as I passed 350 MPH.

Is there any possibility that in the future the cowl flaps (Cylinder Head Temperature Control) and inter-cooler flaps (Carburetor Air Temperature Control ) and oil cooler flaps (Oil Cooler Temperature Control) operation can be made to be operated separately instead of all three opening together all of the time. Only the appropriate cooling flaps would be opened for a specific heat issue among other solutions. This is explained in the "Pilot's Handbook of Flight Operating Instructions For Naval Models F4U-1 F4U-1C F4U-1D F3A-1 F3A-1D FG-1 FG-1D Airplanes British Models Corsair I.II.III.IV" I also think there is a speed limitation for opening the cowl flaps and would reduce the drag hit from having all cooling flaps open when it isn't necessary. The F6F-5 also had the cowl, inter-rcooler & oil cooler flaps controlled separately. The F6F-3 had the cowl flaps controlled separately while the inter-cooler & oil cooler flaps operated together. Information about the F6F 3 & 5 came from "Pilot's Handbook of flight Operating Instructions for Navy Models F6F-3, F6F-3N, F6F-5, F6F-5N Airplanes".

On the American birds we have the mixture choice of Auto-rich or Full-rich, (Wish we had Lean and Auto-lean for flights from Guadalcanal to Bougainville). Using Full-rich above 2,000 feet leads to lower power and black exhaust smoke. Under what circumstances does Full Rich help? Takeoff in an overload condition? Combat below 2,000 feet? According to "Pilot's Handbook of Flight Operating Instructions For Naval Models F4U-1 F4U-1C F4U-1D F3A-1 F3A-1D FG-1 FG-1D Airplanes British Models Corsair I.II.III.IV" the mixture control had three preset conditions: Auto Rich, Auto Lean and Idle Cutoff. The Full Rich position having been eliminated.


-)-MAILMAN-