Spitfire IX overmodeled??

[F4UDOA]

Gents,

Just did some quick looking into our Spit IX and found some odd things.

1. The Spit IX pilots manual shows it should only carry 102 Gallons US or 85 IMP gallons of fuel while ours carries 137 gallons US.

So ours carries more fuel so what. Maybe some later Spit IX's did. However where is the weight of the extra 35 gallons (210LBS) of fuel? Our Spit at 100% fuel weights 7400lbs and that matches the 7,445LBS shown here for the Spit IX with 102Gallons(85Gallons IMP) of fuel. So where is the extra 200+lbs??



Also the fuel consumption rate for plus +15lbs of boost is 130Gallons IMP (156Gallons US) per hour.

That is 102Gallons / 156gallons = .65 * 60minutes = 39.2minutes of duration at mil power. In the MA that should be 20minutes. Instead it fly's for 35minutes at that power setting.

So basically our Spit IX is 200LBS light and flys for almost twice as long as it should.

[Nashwan]

1. The Spit IX pilots manual shows it should only carry 102 Gallons US or 85 IMP gallons of fuel while ours carries 137 gallons US.

So ours carries more fuel so what. Maybe some later Spit IX's did.

I've seen references (although the only one I can find at the moment is Spitfire: The History) to 2 x 18 gallon wing tanks on late production Spit IXs.

Also the fuel consumption rate for plus +15lbs of boost is 130Gallons IMP (156Gallons US) per hour.

That is 102Gallons / 156gallons = .65 * 60minutes = 39.2minutes of duration at mil power. In the MA that should be 20minutes. Instead it fly's for 35minutes at that power setting.

You aren't going by the boost guauge, are you?

The AH Spit IX shows 18lbs boost at WEP, but actually runs at 15lbs boost. I'm not sure what it runs at full throttle (without WEP), but judging from the performance it's just over max continuous power, 12lbs boost.

So AH Spit IX WEP = 15 lbs, full throttle = approx 12 - 13lbs

[F4UDOA]

Nashwan,

No I didn't even look at the MAP gauge. Our gauges are off at times.

I just looked at the Spit performace site at the Spit IX test that is closest to ours as well as checking the Spit manual for fuel consumptions at various power settings. Combat power being +18lbs, Mil power at +15lbs and max for 1 Hour climbing being +12lbs based on what I read. Max continious appears to be +7lbs.

In all honesty our Spit IX is a hodge-podge of different varients melted together and the performance is not overwelming for any varient. So while ours could be a better performer it still appears to be underweight and worst of all IMHO flying for way to long.

This puts A/C that carry much more fuel at a steep disadvantage when facing it if the durations of flight are made to be equal when they were not.

BTW, I have no objections to carrying the extra fuel. Just so long as the weight comes with it.

[Nashwan]

Sorry, I meant 1 hour rating for full throttle, not max continuous.

I just looked at the Spit performace site at the Spit IX test that is closest to ours as well as checking the Spit manual for fuel consumptions at various power settings. Combat power being +18lbs, Mil power at +15lbs and max for 1 Hour climbing being +12lbs based on what I read. Max continious appears to be +7lbs

The AH Spit IX has a Merlin 61. Maximum boost was 15lbs.

The AH Spit IX climbs at 3700 ft/min at sea level, rising to about 3850 ft/min at approx 13,000ft (at WEP). If you compare that to BS 274, a Spit IX with Merlin 61, you find it is very similar:

http://www.fourthfightergroup.com/eagles/bf274.html

BS274 climbed at about 3650 ft/min at sea level, rising to 3,860 ft/min at 12,600 ft, under WEP, which was 15.2 lbs boost.

At "normal rating", 12 lbs boost, 2850 rpm, BS274 climbed at 3200 ft/min up to 13,500, the AH Spit climbs at 3300 ft/min at sea level, nearly 3500ft/min at 14,000ft. The AH Spit is at 3000rpm though, so I think boost is still 12 lbs, or very close to it.

So the AH Spit IX runs at 15 lbs at WEP, 12 lbs at full throttle.

In all honesty our Spit IX is a hodge-podge of different varients melted together and the performance is not overwelming for any varient. So while ours could be a better performer it still appears to be underweight and worst of all IMHO flying for way to long.

Performance is certainly modelled on the worst possible Spit IX, but I'm not so sure about it being underweight. Do you have the consumption at 12 lbs boost? Alternatively, is there any way to run offline at WEP for a lot longer than the 5 min cutout, to measure consumption at 15 lbs boost?

[GRUNHERZ]

Agreed add 200 lbs to the spitfire and cut its endurance.  Isnt it it great when we all get along!!!!

[Guppy35]

It would be nice if they just decided on an actual Spit IX variant and modeled it correctly as it does have too much fuel for an IX.  The VII and VIII had the extra 18 gallon wing tanks but the IX never really did.  

Of course it could carry a 30, 45 or 90 gallon drop tank which made up the some of the difference.

But if they were going to do it right, they'd model the Merlin 66/266 LFIX/LFXVI with the E wing, tropical filter, broad chord rudder and potentially clipped wings that had the three hard points for the 500 pounder or drop tank on the centerline, and rockets or 250 pound bombs on the wings.

And if you really want to be picky about the Spit Vb, if what the HTC website says about it's ammo load is true, then the Vb actually has twice the cannon ammo it should have as the Vb had 60 round cannon drums in each wing.  The Vc had 120 rounds per 20mm cannon, but what we are supposadly flying is a Vb if the look out at the wing is to be believed.

Not that I'm picky

Dan/Slack

[F4UDOA]

Guppy and Nashwan,

I agree our Spits are strange indeed.

The consumption for +12lbs is 105GPH IMP at 2850RPM.

However the engine in the POH chart shows +18lbs as combat power for 5 minutes. This is for the Merlin 61 and 63. Of course this does not correspond with AFDU doc. That would be to easy.

Grunherz,

Wait until I start on the 109 and 190

[GRUNHERZ]

Yes they are horribly undermodeled and I would appreciate any data to pesruade HTC to adress this outrage. By any chance do you have the 1944 data where the Bf109G6 climbs at 10,000 fpm and has a 700mph level speed?

[F4UDOA]

I have some outstanding 109 and 190 data.

I just need an impartial translator.

[Angus]

Good that we all agree, - then things will come to harmony.
So, HTC, please Delete our Spits, - Ia, Vb- IX AND XIV.
Instead, replace with Spit II (rotol airscrew), VC(universal wing), IX LF (clipped/unclipped option,25 boost), and then finally either the XIV-uber-boost teardrop canopy, or simply skip it and go all the way to the Mk 21 or so with a London-Berlin +return endurance


I'm sure the 109 folks are gonna love it

[joeblogs]

It's from a top notch engineer by the name of Goering...

Originally posted by GRUNHERZ
Yes they are horribly undermodeled and I would appreciate any data to pesruade HTC to adress this outrage. By any chance do you have the 1944 data where the Bf109G6 climbs at 10,000 fpm and has a 700mph level speed?

[GRUNHERZ]

Originally posted by F4UDOA
I have some outstanding 109 and 190 data.

I just need an impartial translator.

I'm that person!!!  

[leitwolf]

Post it here.
Enough folks here who can help. Failing that, we'll get at least a nice midweek flamefest.

[Batz]

Here's a question, does anyone know if HT bases the 109G6 specs from the 109G6R6 as tested by Brown. The 109G6R6 had gondolas and roughly matches the AH 109g6 specs.

The speeds of the AH 109G6 in clean configuration are similiar to the speeds of the 109G6R6 original with gondolas.  

The top speed of our clean g6 is around 635km/H at alt when it should be 650km/h.

It's not a big deal either way as 10 mph isn't that significant.

[Ecke-109-]

It's not a big deal either way as 10 mph isn't that significant.

Who would not like to have 10mph extra when he needs to 'extend gracefully' while angry bish hordes slowly comming closer.

Ecke