P-47 150 Octane Speed Tests

[AirWolves=CutCut]

I did a bit of testing with both the D-28 and the D-22 to see what kind of performance the 150 Octane fuel is getting. Below are the results, but first here was the setup.

Both aircraft were loaded with extra ammo and 80% fuel. They flew at 3000 meters in level flight. at 100% Supercharger. 50% oil radiator. 50% Air inlet. 0% cowl flaps.

D-28 Data

Flown at 65 Manifold Pressure

2700rpm = 319mph

2600rpm = 324mph

2500rpm = 322mph

D-28 Data

Flown at 70 Manifold Pressure (Boost or Water Injection Engaged)

2700rpm = 336mph

2600rpm = 337mph

2500rpm = 335mph

D-22 Data

Flown at 65 Manifold Pressure

2700rpm = 329mph

2600rpm = 334mph

2500rpm = 334mph

D-22 Data

Flown at 70 Manifold Pressure (Boost or Water Injection Engaged)

2700rpm = 345mph

2600rpm = 347mph

2500rpm = 347mph

Key takeaway is that 2600rpm seems to be the sweet spot for speed in level flight.

Time available in combat power for both models. (This one was quite drastic)

Flown at 65 Manifold Pressure

2700rpm = 15 minutes before exceed, 20 minutes before engine damage

2600rpm = 30 minutes before exceed, 35 minutes before engine damage

Key takeaway. If you're gonna climb out in combat power, stay at 2600rpm. Also monitor engine temp as you will need to manage cooling on the climb.

Time available in emergency power for both models. (Boost or Water Injection Engaged)

Flown at 70 Manifold Pressure

2700rpm = 5 minutes before exceed, 10 minutes before engine damage
2600rpm = 5 minutes before exceed, 10 minutes before engine damage

Key takeaway. You get 10 minutes of boost before the engine goes bye bye.

 

[Jade_Monkey]

Thanks for the testing, always great to see the empirical data!

 

[Blackhawk_FR]

I'm sharing the results of my test, but done at sea level. 

Speed unit is kph, 2550rpm, cowl flaps closed, oid rad 25%, intercooler 50%. 

 

 

D28 with 150 octane: 

 

68" (combat power): 558km/h for 28min

73" (max with boost): 582km/h for 2min30

 

without 150 octane:

67" (max with boost): 567km/h for 4min

 

 

 

D22 with 150 octane

 

68" (combat power): 574km/h for more than 15min (didnt test until timer limit but probably same as D28)

73" (max with boost): 600km/h for 3min

 

without 150 octane:

53" (combat power): 523km/h

67" (max with boost): 580km/h

 

 

We notice that with 150 fuel, we have a way better speed on combat, a bit faster with the WEP but for a shorter time. 

And also that D22 is faster than D28. 

[SAS_Storebror]

Just throwing in the RL reference data here again:

http://www.wwiiaircraftperformance.org/p-47/p-47.html

http://www.wwiiaircraftperformance.org/p-47/p47d-44-1-level.jpg

 

Gets us a few reference points of 335mph @SL for the D-10 at 56'' HG (so the D-22 at 65'' HG is supposed to be somewhat faster than this).

And 340mph @SL for the D-30 at 65'' HG and 346mph at 70'' HG (these should be good figures for the D-28 respectively at the same manifold pressure).

 

Mike

[HR_Zunzun]

Am I doing something wrong in my testing?

I was doing some speed runs trying to get dev´s specifications at FTH of 22965ft (7000m) standar weight (I suposse is no extras) and 50% fuel. WEP conditions.

I did it in Kuban autum map over the sea (As I understand gives you standar athmosphere conditions for the game). Condition of the plane were:

- 50% fuel (tried with 100% too with same results), standard ammo (8 guns with no normal amount of ammo), no other extras.

-Front cowling flaps closed, oil radiator and intercooler both in neutral.

-Throtle and turbocharged linked and at 100%, rpm at 2700. Achieving 64" HG.

 

I started the test at 7500m and dived to 7000m to accelerate to maximum speed quicker. Once at rated altitude I keep it there as best as I could (good portion within 50ft and almost entire test within 100ft) until the speed stabilised and the engine failed once the time limit was reached (more or less a minute later). Slip ball was mostily centered.

 

After several runs, the maximum speed I could achieve before the engine failed was 299mph (481kph) CAS (IAS).

According to these both converters: http://www.hochwarth.com/misc/AviationCalculator.html and https://aerotoolbox.com/airspeed-conversions/, that translated into 420mph (675kph) TAS (Standar atmosphere conditions).

Dev´s "Aircraft Flight and Technical Specifications and Operational Details" post. listed P-47D-28 speed at 22960ft at WEP conditions (2700 rpm, 64" Hg) as 700kph. Difference from my test is 25kph.

So, before I think of making any claim of under speed, am I doing something grossly wrong? It is the first time I do such a test in kind of a formal way.

One of the tracks: track speed run p-47.zip

 

PD: By the way, I tested at sea level, and when reducing a bit power to match 64"Hg (at sea level full throttle tend to give you a few more inches) I got 344-345mph that is almost exactly as devs specifications of 346mph (I was flying about 100ft so prob that makes for the 1mph of difference).

[CountZero]

Are you using autpilot ? also 100% mix when using boost gives more speed, and inlet try to rais from 50% to something bewten 50-70 i remenber abow some alt that position is better.

[HR_Zunzun]

I have just read your other post regarding the 109 speeds.

I have just used EAS instead of CAS and got a much bigger number (430mph) still 5mph short of the specifications but much closer and logic.

I think I now fully understand why you complained about the lack of TAS indicator. It seem completely unreal having a speedometer that gives you EAS during WW2.