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View Full Version : P-51 and "the behind the cockpit tank"



stalkervision
02-13-2007, 10:03 PM
Is this tank modeled in Il-2 as a seperate useable fuel tank? The reason I ask is that it was well known the p-51 would become very unstab;e due to the cg being all out of wack if this tank wasn't burned down before any aircombat was attempted? Just wondering if it would do the same thing in il-2..

stalkervision
02-13-2007, 10:03 PM
Is this tank modeled in Il-2 as a seperate useable fuel tank? The reason I ask is that it was well known the p-51 would become very unstab;e due to the cg being all out of wack if this tank wasn't burned down before any aircombat was attempted? Just wondering if it would do the same thing in il-2..

Bo_Nidle
02-13-2007, 10:26 PM
No mate, unfortunately we do not have quite that level of detail available to us.

I would also like the ability to switch from external to internal fuel when the drop tanks go.I have read about more than one pilot that dropped tanks forgeting to switch and having his engine quit until he realised his error.

Robin Olds did this in the P-38 as he was lining up on a 109. Both engines quit but he fired and shot it down anyway before restarting his engines. On the History channels excellent "Dogfights" series he claims to be the only pilot in the history of aerial warfare to get a kill in the glide mode!

NonWonderDog
02-14-2007, 11:23 AM
Fuel load has no effect on center of gravity in the sim, and the P-51's CG is not calculated with the fuselage tank full. If it were, it would behave like a laden Yak-9B. (Try it out! Bombs DO affect CG in the sim, and the Yak-9B's bomb bay is in the same place as the P-51's fuselage tank.) Anything you've read to the contrary on these boards is uninformed whining--and there's a LOT of it on this issue.

The fuel gauges appear to show that the fuselage tank is drained last, but this is purely a visual anomaly. No plane in the sim has more than one fuel tank modelled. All the fuel gauges read from that selfsame tank. As they are graduated in units of volume (i.e. gallons) rather than in percentages, the gauge with the lowest maximum value will appear to show full for the longest period of time. In the P-51, the fuel gauge for the (nonexistent) fuselage tank only shows up to the amount of fuel that could be contained in that (conjectural) fuselage tank--rather less than could be held in the (abstract) wing tanks.

This is absolutely more information than you needed, and I understand that, but I'm trying to head off a very long and very ugly b*tch session before it balloons to 13 pages.

p-11.cAce
02-14-2007, 11:32 AM
But the fuel load does affect the FM....does'nt it? Perhaps not the CG but the FM does account for the weight of fuel burned off...I think? http://forums.ubi.com/images/smilies/blink.gif f not I've been wasting a lot of time adjusting fuel loads in the fmb!

NonWonderDog
02-14-2007, 11:37 AM
Yeah, fuel weight matters. The effect of where that weight would actually be concentrated on the real airplane (or rather, the dynamic shifting of such weight) isn't modeled. I think it's the same with ammo weight. As far as I know, only droppable stores have an effect on CG (and maybe moments of inertia, too, but I haven't really noticed).

BlitzPig_DDT
02-14-2007, 11:47 AM
Interesting NWD, but where does your info come from?

NonWonderDog
02-14-2007, 11:51 AM
Multiple posts by Saqson and others on this board. I'm too lazy/busy to look them up. But just try out the Yak-9B, would you? I've been suggesting this for over a year whenever the issue comes up, but no one ever seems to see the relation. The Yak-9B behaves very differently with even a half bomb load--in fact, it behaves exactly like all the reports say a P-51 behaves with a full fuselage tank. If the P-51 in the sim behaved anything like that, the complaint might have merit. But it doesn't. The P-51 has every bit the directional stability of any other plane in the sim.

VW-IceFire
02-14-2007, 12:13 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by p-11.cAce:
But the fuel load does affect the FM....does'nt it? Perhaps not the CG but the FM does account for the weight of fuel burned off...I think? http://forums.ubi.com/images/smilies/blink.gif f not I've been wasting a lot of time adjusting fuel loads in the fmb! </div></BLOCKQUOTE>
Yeah planes like the P-51 definitely handle better with a 25% fuel load than at 100%...but the center of gravity calculation does not change at all. The overall weight does (so wingloading changes for instance) but not where the weight is.

BlitzPig_DDT
02-14-2007, 01:27 PM
Hmm... unless the info comes from Oleg, or is charted out via excrutiatingly detailed testing via device-link, it's suspect.

Not saying you're wrong though.

p-11.cAce
02-14-2007, 02:04 PM
Makes sense to me - continuous CG computations would be quite the load on the cpu!

PF_Coastie
02-14-2007, 02:29 PM
I was told that fuel level is modeled. But not the way most think. If you choose 75% fuel, your plane will "feel" like that for the entire flight. It will not change as fuel goes down.

reisen52
02-14-2007, 02:39 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by p-11.cAce:
Makes sense to me - continuous CG computations would be quite the load on the cpu! </div></BLOCKQUOTE>

Not really CFS2; did it.

CG changed with fuel usage & which specific tanks were selected to be drawn down. Ammo delpetion & underwing stores also effected it.

BadA1m
02-14-2007, 04:19 PM
CFS 1 also had this modelled, I recall the 51 with full tanks to be a real beast, as you flew (or time warped) it got much better.