AI-pack Spitfires flight dynamics?

[ndicki]

I've been trying to catch a bomb-laden Spitfire MkIX with an F.22. I failed. It wouldn't go above about 250kts regardless of what I did, and given that it has a two-stage Griffon knocking out 2,000 horsesworth through a 5-blade airscrew, something is very wrong indeed.

 

I've noticed that while using GregoryP's AvHistory FMs for the S-99/Bf109g-10, the power available is far greater than the standard TW versions, and I suspect that it's the same thing here. Flat out, an F.22 should be capable of nearly 400kts...

 

Does anybody else have this? And if so, what can be done about it? 

[Wrench]

Nigel, is that TAS or IAS you're reading??

 

set the HUDData.ini to Debug=TRUE, and see what the TAS is.

 

TK usually, for the most part, gets stuff pretty close. That having been said however, like you I feel 

 

SLPowerDry=1517499.5

 

is too low. You'll also notice that WEP= TRUE, but there's no statement for

 

SLPowerWEP=

 

someone, much better than I at figuring this out, needs to have a look at it. The same is true for the other DLC Spits. I can almost guarantee they're missing from the S-99 as well (as I'm pretty sure the G-10 had MW50 injection)

[ndicki]

Well, I've tried again and got to 300kts, which is better, but still... I'm on IAS, but with no wind... Anyway, I'll try your TAS mod and see.

 

Not sure how the power ratings work - SLPowerDry=1517499.5 means very little to me! If it's BHP, it's too low. 

[Wrench]

I think -- and am NOT sure!!!- it's newton-meters

[Gatling20]

The figures in the sim are in Watts.

SLPowerDry=1517499.5 = 2035 hp (you divide by 745.7 to convert from the figures in the sim to horsepower).

Edited September 14, 2013 by Gatling20

[+Brain32]

Well, I've tried again and got to 300kts, which is better, but still... I'm on IAS, but with no wind... Anyway, I'll try your TAS mod and see.

 

Not sure how the power ratings work - SLPowerDry=1517499.5 means very little to me! If it's BHP, it's too low. 

 

1 517 499,5 BHP would be waaaaay too much lol it's watts, so 1 517 499,5 W means 1517,5 kW wich in turn makes it 2035 HP which is correct ;)

Edited September 14, 2013 by Brain32

[ndicki]

I was looking at the first two figures 15(00) ! Looks as though it's absolutely spot-on then. Still pretty unresponsive though... Does this suggest that in fact, TW's prop dynamics are out, in that even when you feed in the correct data, the wrong performance comes out? It wouldn't be the first time I've seen that in a sim. The main thing is to achieve correct performance and handling, regardless of the data used to get there...

Edited September 15, 2013 by ndicki

[+Brain32]

I was looking at the first two figures 15(00) ! Looks as though it's absolutely spot-on then. Still pretty unresponsive though... Does this suggest that in fact, TW's prop dynamics are out, in that even when you feed in the correct data, the wrong performance comes out? It wouldn't be the first time I've seen that in a sim. The main thing is to achieve correct performance and handling, regardless of the data used to get there...

 

Yeah it's hard to say, there's prop efficiency entry which I don't understand how it works and really messes up my understanding on how to set up engines for props...

[Heck]

If it's not engine Newtons, then I think you're on the right track with propeller efficiency.  Also, what altitude did this occur at?  I don't have these Spits.  Is it possible something is messed up in the AltitudeTableData of the engine?  No idea what the  PropEfficiencyAdvanceRatioTableData= does, Brain.  But, I think when I get home from work today, I'll mess with one on the stock Spits, just to see what happens when you mess with it.  I learned a long time ago that that's what // is for.  So I restore whatever I break messing around...

[MigBuster]

I was looking at the first two figures 15(00) ! Looks as though it's absolutely spot-on then. Still pretty unresponsive though... Does this suggest that in fact, TW's prop dynamics are out, in that even when you feed in the correct data, the wrong performance comes out? It wouldn't be the first time I've seen that in a sim. The main thing is to achieve correct performance and handling, regardless of the data used to get there...

You have to assume variables in the flight model are incorrect for drag, and lift etc - not as simple as changing the power figure for the engine though.

[+Brain32]

If it's not engine Newtons, then I think you're on the right track with propeller efficiency.  Also, what altitude did this occur at?  I don't have these Spits.  Is it possible something is messed up in the AltitudeTableData of the engine?  No idea what the  PropEfficiencyAdvanceRatioTableData= does, Brain.  But, I think when I get home from work today, I'll mess with one on the stock Spits, just to see what happens when you mess with it.  I learned a long time ago that that's what // is for.  So I restore whatever I break messing around...

 

Yeah Newtons are for jet engine, watts are for piston engines(that includes ground objects too btw.) Altitude is a good option too, I couldn't find the RL chart for Griffon, but I think I do have it for Merlin somewhere...

 

As for "//" - oh yeah, saves the day many times

[ndicki]

You have to assume variables in the flight model are incorrect for drag, and lift etc - not as simple as changing the power figure for the engine though.

Reasonable assumption, both for 'body' effects and prop variables - and there, I really AM in the dark. The only person I know who appeared to really master the flight dynamics system used in SF2 was GregoryP - and he's left flightsimming as far as I can tell. 

 

I was at about 7,000 feet - and the figures I found for the MkXIV stated 390 kts at 7,000 feet. So I'm still about 50 or 60 kts shy of claimed performance. Or at least, if the figures I found were accurate, because of course I can't find them again! 

 

[Fubar512]

390 kt  TAS or IAS?  390 TAS = 448 MPH

 

360 kt IAS @ 7,000 feet = 410 kt TAS

 

 

 

Edited September 16, 2013 by Fubar512