Aces High Bulletin Board
General Forums => Wishlist => Topic started by: MachFly on January 24, 2012, 12:33:22 AM
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The current order of the way Spitfires drain fuel from their tanks is: Drop, Wings, Bottom, Top. In reality Spitfire pilots would drain the top fuel tank first and then the bottom. The way the Spitfire's fuel system works is the fuel taken from the bottom tank, as you start having extra room in the bottom tank the fuel from the top tank would poor down into the bottom. Bottom fuel tank is self sealing and armored, top is not, so you want to empty your most vulnerable fuel tanks first.
I'm not exactly sure why but I've read that it's also better for weight distribution to drain the top fuel tank first. Also I don't know this for a fact but I don't believe the Spitfire isn't even capable of taking fuel directly from the top tank.
I recommend we change the automated order of draining fuel tanks to: Drop, Wings, Top, Bottom.
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The way the Spitfire's fuel system works is the fuel taken from the bottom tank, as you start having extra room in the bottom tank the fuel from the top tank would poor down into the bottom.
Why does the order of the fuel tanks need to be changed if all draining from the bottom does is drain the top?
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Fly a 109 instead, or one of the Ki's... Problem solved... :D
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Well if it was really 1 tank combined (no pumps, just a straight up gravity drain) shouldn't it only be showing as a single tank? A hole in either one would cause a drain, would it not? You get a hole in the bottom tank and you'd lose the top as well, right?
So why not have HTC model it as a single selectable tank (but keep where HTC has modeled the different bullet proof protection for the different parts of it)?
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Well if it was really 1 tank combined (no pumps, just a straight up gravity drain) shouldn't it only be showing as a single tank? A hole in either one would cause a drain, would it not? You get a hole in the bottom tank and you'd lose the top as well, right?
So why not have HTC model it as a single selectable tank (but keep where HTC has modeled the different bullet proof protection for the different parts of it)?
Technically that works too. Officially they were considered to be different tanks though, and I figured it would be a lot easier to change the order than redesign the whole fuel system.
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Why does the order of the fuel tanks need to be changed if all draining from the bottom does is drain the top?
In AH you normally empty out the bottom tank first and when that's empty you start using the top. In reality you don't run out of fuel in the bottom tank unless your out of fuel in the top tank.
Fly a 109 instead, or one of the Ki's... Problem solved... :D
lol
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Well, that begs the question: Could you even select the top tank in a Spitfire? Or did you select one setting and it drained automatically for you?
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This should clarify all the specifications.
Took this from Pilot's Notes for SpitIIAII and IIB
(http://img685.imageshack.us/img685/70/snotesspitiiaiiandiib.jpg)
Took this from Pilot's notes for Spitfire VA, VB, VC, IB, IIC, III
(http://img521.imageshack.us/img521/6645/snotesforspitfirevavbvc.jpg)
Took this from Pilot's notes for Spitfire IX, XI, & XVI
(http://img441.imageshack.us/img441/5627/snotesforspitfireixxixv.jpg)
Took this from Pilot Notes for Spitfire XII
(http://img28.imageshack.us/img28/1535/pilotnotesforspitfirexi.jpg)
Took this from Pilot's notes for Spitfire XIV and XIX
(http://img855.imageshack.us/img855/284/snotes.jpg)
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(edited - see below)
strange that none of the diagrams show the pressurization line for the drop tank :headscratch:
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if you look at the tank capacities the drain order is actually correct, its just the AH labels that are swapped. (ie. Main should be Top and vice versa)
What do you mean by "main"? A few years ago the top fuel tank on the Spit14 was labeled as main but now they made it like all other Spits, just top and bottom.
In AH's Spitfires the top fuel tanks is the largest, these diagrams show the top fuel tank to be the largest as well (excluding the Spit14).
BTW looking at the Spit14 fuel diagram it looks like the AH Spit14 has a screwed up fuel system. Apparently the real 14's bottom fuel tank was the largest (not the top as in AH) and we don't even have an aft tank.
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(edited - see below)
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oops I mean the Top and Bottom labels are swapped :)
You mean for the 14? Because I think the Merlin AH Spitfires have a properly set up fuel tanks (excluding the order in which they are used).
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strange that none of the diagrams show the pressurization line for the drop tank :headscratch:
I think that's because these diagrams are meant for pilots, not mechanics. Mechanics would have a much more specific diagram.
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(edited - see below)
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for our merlin spits the drain order is correct, ie. 48gal (Upper Tank) then 37gal (Lower Tank). Assuming the Pilot's Notes are correct, its just the AH labels which are wrong. In AH the 48gal is incorrectly called Bottom and the 37gal Top.
Havent checked the AH XIV but it should drain 36gal (Upper Main) then 49gal (Lower Main).
I'm pretty sure in all AH Spitfires the top fuel tank is the largest, and they are all programmed to first take fuel from the bottom tank then top. I don't know of a way to find out the exact amount of fuel that each fuel tank holds on AH spitfires, however looking at the time it takes to burn the fuel from each tank I've noticed that the top tank is the biggest.
Actually I just realized of a way to test the amount of fuel each fuel tank holds on AH spitfires. While being leveled and at a constant power setting we can burn off each tank, e6b will give you the fuel burn rate and we can time how long it takes to burn off the whole tank. This will allow us to calculate the amount of fuel in each tank.
Unfortunately I do not have time to do the test right now.
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sorry deleted the above as I got mixed up there with the XIV. as tested offline:
Mk. I, V, IX, XVI:
RL order: Upper (48 gal) -> Lower (37 gal)
AH order: BTM (44 USgal) -> TOP (58 USgal)
so although labelled correctly, the drain order is reversed, as you said.
Mk. VIII:
RL order: Wing (28 gal) -> Upper (47 gal) -> Lower (49 gal)
AH order: LW/RW (34 USgal) -> BTM (59 USgal) -> TOP (56 USgal)
again labelled correctly, but the drain order is reversed, as you said.
Mk. XIV:
RL order: Wing (26 gal) -> Upper (36 gal) -> Lower (49 gal)
AH order: LW/RW (32 USgal) -> BTM (44 USgal) -> TOP (58 USgal)
the drain order is correct, but the labels are reversed.
the Rear (31 gal) tank would be nice to have on the XIV too, but thats for another discussion :)
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I always drain the top tank first on the IX. I do notice it has less of a tendency to get into the ugly spit tailslide. Probably psychosomatic. A few years back someone explained tank order to me and since then I have just done it.
On the eight I burn wing, then top.
If carrying a DT I burn DT to climb alt thats it, then drop. Just my personal TTP.
Great post from the manual.
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Almost no spits had the tail tank, as it was unsafe for flying. Especially when belly tanks could hold more than that.
I guess the question I have is: From the pilot perspective in the cockpit, can you select top and bottom tanks? Or was it just ONE option (i.e. "main" or "fusealge" etc)? Wing tanks appear to drain into the top, which appears to drain into the bottom... Can you even select them? Or was it all feeding the bottom tank and you NEVER switched the fuel selector (excluding drop tanks)?
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looks like switching between drop/mains/rears were the only 3 options. the left wing, right wing, upper and lower tanks function as effectively one tank, so shouldnt really be switchable (although they should be modelled as separate tanks for damage & mass reasons.)
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What do you mean by "main"? A few years ago the top fuel tank on the Spit14 was labeled as main but now they made it like all other Spits, just top and bottom.
In AH's Spitfires the top fuel tanks is the largest, these diagrams show the top fuel tank to be the largest as well (excluding the Spit14).
BTW looking at the Spit14 fuel diagram it looks like the AH Spit14 has a screwed up fuel system. Apparently the real 14's bottom fuel tank was the largest (not the top as in AH) and we don't even have an aft tank.
The aft tank wasn't carried much if at all in wartime XIVs. Same with the IX or XVI.
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yup Morgan states rear tanks only for the XIVe, which was only a handful of the XIVs, and it doesnt say if they were fitted to all of them. as I think you mentioned in another thread, theres hardly any photos of spits with rear filler caps.
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Modeling fuel leaks would be rough. A leak in the bottom tank would gradually drain the entire fuel supply. A leak in the top tank would drain fuel from the wing and top tanks, but not the bottom tank. A leak in either wing tank would drain it, but not the opposite wing tank nor the top or bottom tanks.
I am not sure AH is set up to model that.
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No different from P-47s or 109s, where a leak means you lose all gas. The point where you get 1 effective tank, I mean.
I'm sure HTC can model it to do a hierarchical drain pattern.
IMO it should be set up that way. It's the finer details like this that make AH shine. Get a leak in the wing? Stops there. Get a leak in the bottom? You slowly lose it all. Mind you that bottom tank is more heavily protected, so it's not as likely as leaking from another tank.
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Modeling fuel leaks would be rough. A leak in the bottom tank would gradually drain the entire fuel supply. A leak in the top tank would drain fuel from the wing and top tanks, but not the bottom tank. A leak in either wing tank would drain it, but not the opposite wing tank nor the top or bottom tanks.
I am not sure AH is set up to model that.
Yeah I don't see HTC modeling that.
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Mk. XIV:
RL order: Wing (26 gal) -> Upper (36 gal) -> Lower (49 gal)
AH order: LW/RW (32 USgal) -> BTM (44 USgal) -> TOP (58 USgal)
the drain order is correct, but the labels are reversed.
See the problem with this is not just the reversed labels but the fuel tanks are actually reversed. If you get hit in the top tank the one that is labeled "top" will start loosing fuel. So in AH the fuel tanks are physically reversed.
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Almost no spits had the tail tank, as it was unsafe for flying. Especially when belly tanks could hold more than that.
I guess the question I have is: From the pilot perspective in the cockpit, can you select top and bottom tanks? Or was it just ONE option (i.e. "main" or "fusealge" etc)? Wing tanks appear to drain into the top, which appears to drain into the bottom... Can you even select them? Or was it all feeding the bottom tank and you NEVER switched the fuel selector (excluding drop tanks)?
Looks like it's treated as one fuel tank.
from Pilot's notes for Spitfire IX, XI, & XVI
(http://img803.imageshack.us/img803/6718/capturejyt.jpg)
Every time they tell you which fuel tanks to select they call top and bottom tanks simply as "main tanks".
BTW if anyone wants the actual files send me a PM with your email and I'll email them to you.