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Flight model tweaking - Printable Version

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+---- Thread: Flight model tweaking (/showthread.php?tid=51403)

Pages: 1 2 3

- GerritJ9 - 10.01.2008

Since the Brewsters are my favourite planes, I have long been annoyed by the inaccuracies in their performance. Turns out that the FB/PF Buffalo Mk. I has the same Flight Model as the B-239, which is totally incorrect; the Buffalo Mk. I was faster thanks to its more powerful engine (1100 vs. 950 hp and lower drag due to its new cowling) but due to its considerably higher weight had a lower rate of climb and wasn't as manoeuverable. I sent data on the Brewsters to 1C ages ago, but nothing was done, except when patch 4.03(m) was launched: on the Buffalo, the ammo load for the wing guns was cut from the historically accurate 500 rpg to 250 rpg, without any mention in the readme as to the reason for this.
Examining the 4.05m Flight models reveals a number of discrepancies and I will be correcting them based on data from the following:
Warplanes of the Second World War: Fighters volume 4 by William Green
Porfile Publications 217: Brewster Buffalo
F2A Buffalo in Action by Jim Maas
Le Brewster Buffalo by Jean-Louis Couston.

The B-239 FM is pretty accurate as far as top speeds go at sea level and rated altitude, but the empty and loaded weights are a bit high. These figures are totally inaccurate for the Buffalo Mk. I however and this will require a separate FM to do justice (or injustice?) to this bird.
The F2A-2's FM is out with regard to speeds: 428 kph (1C) vs 466 (Couston) at sea level; 480 at 4750 m (1C) vs 554 at 4500m (Couston and Maas). Also, there are weight discrepancies.
I will also add the Dutch B-339C (1100 hp Cyclone) and B-339D (1200 hp Cyclone) with their different armament, and possibly the F2A-3; this one presents some difficulty since it has several extra fuel tanks which the other Brewsters did not have, so I may have to compromise on this one with regard to fuel capacity. Other possibilities are a Buffalo Mk. I Field Mod (also known as SSSS, or Shadow Super Sport Special) and an unarmed PRU Buffalo. If there is enough interest I will release the new models, which can be added like the Bf-109F-1 and Spitfire IB and IIB were. These mods will be available for 4.05m ONLY and NOT for 4.08m.

- Former_Older - 09.02.2008

Everyone-please consider this:

changing FM is possible. It must be

There are many planes we feel are "wrong". if it were to be changed, how do we know it is "right"? By how it "feels"? matching raw data to flight tests? Anecdotal evidence? Best guess?

The overwhelming majority wants changed FM in some way. Do we understand what this really means, and what it entails? We claim it's for "accuracy" most times

I am very sorry but my feeling is that there is nobody in the community who has the credentials, on their own, to say what is actually "right" or "wrong" on overall FM for any plane. I cannot just accept that somebody who can change an FM (and with the purpose of "correcting" it) will do so and also make it "correct". How many Aeronautical Engineers are here? How many AEs here have practical knowledge of these planes? I studied AE for a time, and I know a lot about some of the planes in the sim and I know that I do not know enough to accurately modify FM. I can tell you where a few things are probably wrong, and an even smaller group is definitely wrong- but does the knowledge or belief that it is "wrong" also empower me to know what's "correct"

No, it does not

I fear the hack for one reason only: that we will change the FMs, and 100% without question I can safely assume that this will be in an attempt to make things "right", but we will instead of getting something "right", we will simply exchange an old error for a new one. An old pet peeve of the community will be changed, I fear it will be changed in good-intentioned error, and we will have a new innaccuracy- but since it is new it will be accepted as correct. "New" does not equal "correct", gentlemen!


Can anyone here claim to be impartial to FM and aircraft performance, and also savvy enough in the engineering principles AND the practical side of these aircraft? How do I know that anyone who changes FM is anything more than an armchair engineer who saw a show on the History channel, and now knows everything? This is like turning off the lights and firing a gun into the room. Who knows what you'll hit

This is dangerous territory in my mind. We'd do well to talk these things out with guys like the 1% Team for CFS3

- panzerkeil - 09.02.2008

I would have to agree with former_older.
I fear that it will never be possible to satisfy everybody and the community will fall apart in real wars..

- Trooper117 - 09.02.2008

ok.. so what happens when we introduce a new aircraft type?
It's being worked on right now, and we have the real possibility of brand new flyables in game.
Are you going to stand up and say "his credentials are crap, he only got these figures from the internet so they can't be right".. I think not.
The time is coming when we will have Lancasters, Typhoons and Whirlwinds in the not to distant future.
Lets be realistic about this. It's a game, and a good one.. No-one will die because some of the flight parameters may be out slightly. We are playing a very enjoyable game, but this isn't real life, so when FM is able to be applied by the modders, and it'll come, no doubt about it, lets not shoot the golden calf..

- VT-51_Razor - 09.02.2008

I'm not posting here as either for or against messing around with an existing FM, or even coming up with a FM for a new plane that has been developed. I just thought I'd share my recent experience with y'all.

I am a pilot for a helicopter company that is in the process of trying to get a simulator built for the rather unique type of helicopter we fly - the S-64 Skycrane. In this process, I have been to several different simulator manufacturers to discuss their bids, and it has been a real education for me as to exactly what goes into the making of the Flight Model. The amount of instrumentation/sensors that will have to be placed on the aircraft is amazing, and the number of flight test hours that will have to be flown is around 40 to 60 ! This is for a FAA certified Level 6 FTD (a Flight Training Device is a non motion simulator) - Level 3 for the JAA.

The point being, there is so much empirical data that goes into it to even get close, then pilots are necessary to fly it and evaluate the "feel" of it for further "tuning". In our case, we have the actual aircraft and pilots, but for this game, we have neither for all practical purposes. Based on what I have learned so far, I'm quite sure that Oleg has missed the mark on several models of his, but I have also learned enough to know that there is no way anybody in this community will ever be able to say that they can do better.

- Trooper117 - 09.02.2008

Absolutely mate!.. The game we have, and it is a game, can not directly compare to a real simulator.. But I'm sure that some people who play it think that it does.
I've always enjoyed the game for what it is, and marvelled at the efforts people have made to enhance our enjoyment further. I can't for the life of me understand how people will literaly go to war, waving facts and figures claiming they are 100% correct over a flippin game!
I love this thing as much as anyone, but I don't over analyse the flight models because someone in another aircraft has managed to turn inside me and gain an advantage, yet according to the 'facts' they shouldn't be able to, therefore the flight model must be wrong!! I just fly with what I have and try to find a way to use it to get the upper hand. The most important thing is to enjoy the 'game' to its fullest..

- Tigershark - 09.02.2008

Does anyone remember EAW, and how well the community fine tuned the FM of all the planes...??
I recall REAL WWII pilots, who were pleased with the sim, liking the FM very much...

And I dont believe I observed anyone abusing it when hitting up online... That community had some REAL die hards...

I would love to see the IL2 scene with that level of sophistication and respect, and I think it CAN be done...

vive le IL2

TS

- Former_Older - 11.02.2008

In the past, I had put out the idea of getting together some type of review board that can recommend this sort of thing.

Example: There are say, 20 people on such a board. each has a general knowledge of the subject of aviation in WWII, and would be more specifically knowledgeable in particular aspects of various aircraft. They would fly a virtual plane, and get an overall reaction, and those with specific knowledge of that plane would explain to the whole why, or why not, the tweaks were more or less "right" or "wrong".

In this way, the idea of a reviewing body that has credentials (members would need to back up their thoughts on an FM with evidence enough to make his or her point) and could be trusted would be established. A "seal of approval" from such a group would be a good indicator as to whether an FM was good or bad

I also have suggested talking to the 1% Team guys who mod CFS3 and asking how they go about it

The whole idea is to make a reliable baseline and hopefully a quality standard for modding FM

Things like "feel" and anecdotal evidence are a good portion of what we might have commonly used as basis for FM. As long as that is a plausible set of circumstances that does not contradict flight data and the standpoint that an FM tweak based on that evidence is closer to reality than it might be without the tweak, then I see no issue

I think some way of reviewing and testing by a third party would be ideal

Razor makes a great point- even Oleg and RRG made mistakes, and I think he hits the nail on the head in his assesment.

I think that possibly if there was a third party reviewing what they did- not part of the dev team and not under employ of either- that if somebody had say "Hey now, this isn't right, and here's the reasons I feel that way", some of the larger errors could have been avoided

I feel a lack of a certain amount of circumspection was present- people were too close to the subject to be truly objective

I see an opportunity here to present that objectivity

- spud - 12.02.2008

Looking at the FM files that have been posted, there are some issues that are almost certainly pretty subjective. The Damage stuff. Look at the "toughness" values. Why are the ailerons on the bf109s "100" where almost all other aircraft (fighters) are "50?"

Why does the F4F have asymmetrical toughness left vs right, and no other plane in the game does?

I looked at all of them, and the toughness seems pretty arbitrary, frankly.

The Sally is tougher in many respects than the A-20s. What empirical data is such a claim based on?

Or the control lockup speeds. Bf-109s? None. P-38J, 248mph.

There are others that are flatly wrong or arbitrary.

I haven't seen the weapon files, but josse said that the .50 cals have no API, for example (contrary to what we've been told). The A6M5s have german guns. I don't always have a problem with things like that, if the IJN and LW 20mm (for a specific gun/ammo combo) were within x% of each other, why bother making a special gun for the IJN? If it is easy to make a unique one and there is enough difference though, then why not?

I do think damage needs to be tweaked for "feel," frankly. The damage models are simply not complex enough to rely on "simulation."

- FC - 13.02.2008

There are things that are clearly wrong in FM and can be corrected relatively easy. In fact basic FM is not that bad at all but game fails in fine tuning some of the individual planes. They just have too many planes to deal with and Oleg don't have enough people to make top class job in FM department.

It's not that hard to see which FM changes are good and which one are not, every FM change should be documented and in game and RL performance numbers should be attached to mod. If modded plane matches RL better than Oleg's than change is justified IMO.

spud Wrote:Looking at the FM files that have been posted, there are some issues that are almost certainly pretty subjective. The Damage stuff. Look at the "toughness" values. Why are the ailerons on the bf109s "100" where almost all other aircraft (fighters) are "50?"

Why does the F4F have asymmetrical toughness left vs right, and no other plane in the game does?

I looked at all of them, and the toughness seems pretty arbitrary, frankly.

The Sally is tougher in many respects than the A-20s. What empirical data is such a claim based on?

Or the control lockup speeds. Bf-109s? None. P-38J, 248mph.

There are others that are flatly wrong or arbitrary.

I haven't seen the weapon files, but josse said that the .50 cals have no API, for example (contrary to what we've been told). The A6M5s have german guns. I don't always have a problem with things like that, if the IJN and LW 20mm (for a specific gun/ammo combo) were within x% of each other, why bother making a special gun for the IJN? If it is easy to make a unique one and there is enough difference though, then why not?

I do think damage needs to be tweaked for "feel," frankly. The damage models are simply not complex enough to rely on "simulation."

I'm surprised to see such a simplified view from you, those damage numbers are just modifiers and you know that in simulation output is more important than input so these numbers don't mean much as long as results are close to RL.

Perfect example is the one you choose, Bf109 don't have "lock up" speed and P38 have, end result is virtually the same, both planes suffer badly from unresponsive controls.

Your comment on .50 is wrong, API is modeled, belt composition is suspicious though. You can see more about effectiveness of .50 in game here.

http://www.acompletewasteofspace.com/mo ... ic&t=15671

Don't get me wrong, some of the things in game are joke but there are lot of myths that have been perpetuated in Il2 community for a long time.

FC

- spud - 14.02.2008

I realize there is a lot more there, but the FM text files are all I have seen, so it's what I have to work with. The F4F asymmetry is troubling since no other planes have it (I looked at all of them). DMs are extremely complicated, and a huge can of worms, I realize.

Note that gibbage has some good posts on this at ubi regarding the poor effect of .50 cal. As for the APII, I know the belting is off, but I also thought josse said that the API have the same AP value as a minen round (effectively zero). Again, I have yet to see those files, so I'm talking out my ass Big Grin

tater

- Guest - 14.03.2008

Curtiss P-36A,or Hawk 75A3

Propulsion

Powerplant: Pratt & Whitney R-1830
Horsepower: 1050 hp

Performance:
Range: 830 miles (1336.00 Km)
Cruise Speed: 250.00 mph (402.00 Km/H)
Max Speed: 313.00 Mph (504.00 Km/H) ___(in il-2 434km/h)
Ceiling: 32700.0 Ft

Curtiss P-36G, or Hawk 75A4

PERFORMANCE:

Engine(s): 1 x Wright R-1820-G205A Cyclone piston radial engine generating 1,200hp.
Maximum Speed: 322 mph | 518 km/h | 280 kts ____(in il-2 459km/h)
Maximum Range: 650 miles | 1,046 km
Service Ceiling: 32,349 ft | 9,860 m | 6.1 miles
Climb Rate: 2,500 ft/min (761.6 m/min)


ARMAMENT:

External Hardpoints: 1
Armament:
4 x 7.62mm machine guns
2 x 12.7mm machine guns

Morane Saulnier MS 406

Performance
Maximum speed: 486 km/h at 5,000 m (290 mph at 16,400 ft) ____(in Il-2 is 440km/h)
Range: 1,000 km (620 mi)
Rate of climb: 13.0 m/s (2,560 ft/min)
Wing loading: 141.9 kg/m

- Former_Older - 31.03.2008

I can know, with 100% surety, when an FM is wrong.

How do I tell, when I tweak the FM, what's "right"? Raw numbers? You can screw up the FM and still hit the numbers. I can make a plane hit it's FPM target in climb...it might now fly straight up at that rate, but I can duplicate those numbers

Food for thought. Things are not cut and dried