Acceleration comparisons

[JtD]

You'll need to engage low gear (2nd stage in game) in order to get any benefit from water injection. Both with and without water injection you're operating above full throttle altitude, where the benefit of water injection is nearly zero.

I would like to know what your "generally accepted" speed performance figures for the Wildcats are. I can tell you right now that they match or exceed the figures given in Americas 100000 as well as the figures quoted on ww2aircraftperformance.com.

F6F and F4U performance is modelled for clean aircraft.

[horseback]

Originally Posted by majorfailure

Again: Just because an an engine model does more hp at some alt, it does not mean it does more hp at any alt. 5kft is near FTH of first stage of F4F -good alt for it. Try at 5km alt - FM-2 will be better than F4F.

Every source I have shows the FM-2 superior to the F4F-3/4 up to around 18-20,000 ft. The same site you link has tests for both which indicates that the FM-2 at 5K will do a bit over 310mph, or within an eyelash of 500kph; the F4F-4 at 4500 ft is listed at 283 mph or 455 kph, a difference I consider significant.

At http://www.wwiiaircraftperformance.org/f6f/f6f.html I can find only 315mph at 5kft for an F6F-3 without water injection. Other tests are either with water injection, do not cover that alt or are not fully loaded fighters.

I can't find much mention whether the engine was a plain vanilla -8 or -10, or a -8W or -10W, which indicates water injection, but it was not always noted back then. That still leaves the questionable performance of the F6F-5, which should do at least 330 mph at that altitude, or about 15-20 kph more than I could get in seven test runs.

http://www.wwiiaircraftperformance.o...6f-3-02982.pdf
is interesting because it states that early F6Fs were problematic to rudder trim in a power climb.

I don't know if you're a native English speaker, major, but we refer to this sort of thing as "cherry picking." I'm sure you'll find it a useful term.

Like many high performance fighters, the rudder corrections for extreme changes in speed (as experienced in a sudden climb or dive) could not be rolled in quickly enough on the Hellcat, sometimes requiring the pilot to exert pressure on the rudder pedals; the same phenomenon was noted for the P-40, P-47, P-51 and the Corsair to some degree, much greater in the case of the P-40 (meaning that the Warhawk was a couple of orders of magnitude worse than the Hellcat), about the same as in the P-47 and less in the other types. If the rudder issues you refer to consist of the notation on page 8, it was a minor issue and quite acceptable (and clearly superior to the rudder input demands placed on a pilot flying a Bf 109 or FW 190). AFAIK, it was common to all models of the Hellcat, and considered a fairly mild vice.

Edit: The reason it was mentioned is that the original contract probably specified that rudder forces would be trimmable throughout the aircraft's performance (I'd have to re-read Tillman's book to be sure); this turned out to be impossible with the engine and propeller changes from the original R-2600 and Curtiss Electric combination envisioned for the Hellcat, so it was just noted and signed off on every acceptance test rather than go to the massively complicated task of revising all the contract documents in the possession of Grumman and the Navy Department (this was the age of hand-typed documents and carbon copies, remember; they hired thousands of young women to type and file and keep track of all the hard copies, and had warehouses full of the original documents) and getting them re-signed. I can tell you from personal experience that some government contracts still get this sort of standard waiver treatment for minor issues and that if the government rep who had to inspect the paperwork was transferred, you'd better be able to produce the original paper trail for his or her replacement.

cheers

horseback

[horseback]

Originally Posted by JtD

You'll need to engage low gear (2nd stage in game) in order to get any benefit from water injection. Both with and without water injection you're operating above full throttle altitude, where the benefit of water injection is nearly zero.

I would like to know what your "generally accepted" speed performance figures for the Wildcats are. I can tell you right now that they match or exceed the figures given in Americas 100000 as well as the figures quoted on ww2aircraftperformance.com.

F6F and F4U performance is modelled for clean aircraft.

The 'HUD' message telling you that water injection is engaged goes up even so. Who knew that the game would lie to me like that?

As mentioned in an earlier post, ww2aircraftperformance.com shows a test for the FM-2 with a level speed at 5000 ft of 312 mph true (502 kph); an F4F test for 4600 ft shows a true airspeed of 283 mph (455 kph).

Attached is a blowup of the chart from America's Hundred-Thousand for the Wildcats' various models' Speed and Climb performance, scanned from the book and then printed on graph paper in the forlorn hope that it would be made a bit clearer (Murphy made his usual appearance, alas). The FM-2's speed graph line is highlighted in pink, the F4F-4 is in blue and the F4F-3 is in green. As you can see, the FM-2's line at 5000 ft is clearly east of the 300 mph line, while the F4F-3/-4's lines are well to the west of it, around 285 mph.

I used the same references you claim you used.

cheers

horseback

[horseback]

Originally Posted by jameson

"There's a gazillion of tests showing 520-530 kph on the deck for G model 109's at combat power."
JtD, lol. Try it ingame and let us know how fast you can get it, 480? if that? At 110% I get sometimes 520ish...
A minute of climb at 110% in a fight can be an awfully long time and would be even better if ingame matched RL "historical" peformance. If it did there'd also be more grunt throughout the power curve ingame. Takeoffs would start to get very interesting with correctly modelled torque. Forget to lock the tail wheel in RL and the rudder couldn't stop it making a left turn, with usually fatal results... Ingame?
Gunz I believe that WEP is water injection, it may be in the manual, been a while though since I read it.

Try closing your radiators at about the time you hit 450 kph indicated; it will bump up your top speed and final stages of acceleration a bit, as long as you count to about 30 seconds or so after the overheat message pops up and then open them up and slow down.

I can't imagine adding RL levels of torque in the game at this point in its life; the 109 and P-40 would become almost impossible, never mind 'interesting', to land or take off for the vast majority of players.

Personally, I already have a full 'whine' cellar.

cheers

horseback

[JtD]

The HUD tells you the water injection is active because it is. It works above full throttle altitude. It did in real life. There's just no increased boost any more, and therefore there's no meaningful extra power. As it is in real life.

In game, the F4F manage around 295 mph at 5000ft. So clearly, the Wildcats do not "fall well short of generally accepted performance figures". Two of them are clearly overmodelled, and one of them falls "somewhat" short of generally accepted performance figures, and that not even at all altitudes. Unfortunately though, at the important ones.

[MaxGunz]

Originally Posted by horseback

I can't imagine adding RL levels of torque in the game at this point in its life; the 109 and P-40 would become almost impossible, never mind 'interesting', to land or take off for the vast majority of players.

That's low speed nose high propwash. Use rudder, not side stick. Keep the prop revs high and power low in case you have to go around.

Funny thing how I read from guys allowed to try out a 109 because they qualify and still going off the strip just trying to take off the first time.

[Woke Up Dead]

Originally Posted by JtD

The HUD tells you the water injection is active because it is. It works above full throttle altitude. It did in real life. There's just no increased boost any more, and therefore there's no meaningful extra power. As it is in real life.

I think IL2 Compare helps you figure out at what altitude boost no longer makes a difference. There are two lines on each maximum speed graph: the speed at 100% throttle, and the speed at 110%/boost. In some planes, like the Hurricane and Spitfire, the two lines meet at 4-5000m.

[majorfailure]

Originally Posted by horseback

I can't find much mention whether the engine was a plain vanilla -8 or -10, or a -8W or -10W, which indicates water injection, but it was not always noted back then. That still leaves the questionable performance of the F6F-5, which should do at least 330 mph at that altitude, or about 15-20 kph more than I could get in seven test runs.

Most test documents state the engine the plane was equipped, if not usually it can be deduced from loadout given, there is some amount (16gallons?) of anti-detonant mentioned when water injection was used.

The document above states: "Rudder trim effectiveness was not sufficient to trim in the high power climb." If I get this correctly it means though FULL rudder trim was applied in a high power climb the plane still deviated from flying straight. So at least early F6F-3s were trim hogs in rudder when climbing with full power - and I doubt that later model F6F behaved much different - even if a larger trim tab or different rudder were added, changing from clevel flight to climb would still require lots of trim change in rudder.

Water injection does "move" the power curve towards more power AND towards lower alt. So while the F6F-3 will be faster with first stage of the charger at 5kft (FTH~1000m), the F6F-5 will be faster when water injection is engaged in the second stage at that alt.
Same for the Corsairs: F4U-1 in first stage and F4U-1A in second stage when using WI above~1000m.
Water injection will work and will use water/methanol mix in first stage though, BUT will not have much of an effect.

Just compare the two power curves of the F6F-3(without WI) and and the F6F-5 in IL2compare. (Or F4U-1//F4U-1a)

[jameson]

Horseback, thanks for the effort you've put into this thread and my apologies for hijacking it somewhat. Your suggestion regarding 109 radiators is noted and I'll give it a go. In RL according to Finnish 109 pilots. the effect on speed was pretty minimal to the point of not being noticed, whether rads were open or closed. If 109G6's ever get an fm makeover perhaps this'll get fixed as well.
There was a very early mod from the AAA days which did up the torque effects for the 109, how accurate it was I couldn't say, but slamming the throttle to the wall at take off wasn't wise as it did have a gap where the rudder was non resposive and if the tail was lifted too early it got a bit tense!

[horseback]

Originally Posted by JtD

The HUD tells you the water injection is active because it is. It works above full throttle altitude. It did in real life. There's just no increased boost any more, and therefore there's no meaningful extra power. As it is in real life.

In game, the F4F manage around 295 mph at 5000ft. So clearly, the Wildcats do not "fall well short of generally accepted performance figures". Two of them are clearly overmodelled, and one of them falls "somewhat" short of generally accepted performance figures, and that not even at all altitudes. Unfortunately though, at the important ones.

I used the term 'well short of accepted figures' for the Navy fighters as a group, which was a bit sloppy of me. The Wildcats are, however, shockingly sssllllloooooowwww by any measure; over 10 seconds to gain a bit over 6 miles an hour can seem like hours after testing the Corsair at sea level. When you're struggling to maintain level flight by detecting whether the altimeter needle is moving (the variometer is at least a second behind the curve), the intervals take forever to go by, and when you finally reach the point where there just ain't no more, you glance at the speedbar and think "WTF?"

Even if they are about 20 kph faster than they should be, that impression is hard to shake.

In any case, the FM-2 is poorly represented, and if former pilots' direct testimony to me is to be believed, the tall-tail Wildcat could accelerate with the Zeros and Oscars they encountered in the Marianas and the Philippines (the old guys picked out all of the Japanese fighters from my then-extensive collection of 1/72nd scale models and named each one --and corrected some of the color choices I made). Even accounting for the usual hypercompetitive BS factor present any time Navy veterans of any age meet, that means that like its climb, the FM-2's acceleration should be pretty good as well, even if measured against beat-up, poorly maintained A6M5s of the later war period. My former landlord said (realizing for the first time that my wife was present) that the FM-2 was "a he-heck of a lot uh, peppier than the Dash Fours or even the Threes."

If it was anything like the one we have in Il-2 '46, there wouldn't have been three 70-something year old men in my living room that day in 1985.

cheers

horseback