Aces High Bulletin Board

General Forums => Aircraft and Vehicles => Topic started by: badhorse on March 20, 2007, 06:56:48 AM

Title: Spit fuel management
Post by: badhorse on March 20, 2007, 06:56:48 AM

I believe it is the XIV model of the spit that has four tanks (not counting the external). A top, bottom, Left Wing and Right Wing.  Is their any reason to manually select a tank or just let the auto feature take care of it?

I ask because I was told on the FW-190 you should burn your aft tank down to half and then go to auto to improve flight characteristics.  So I was wondering if the same held true for the spit.

thanks

Title: Spit fuel management
Post by: Masherbrum on March 20, 2007, 07:16:22 AM

The Spit 1 is the best of the Spits.

Title: Spit fuel management
Post by: Bruv119 on March 20, 2007, 08:21:20 AM

Shift F selects what fuel tank to burn pressing it again will cycle through.

Please note that it will turn yellow.  Once the one highlighted burns out your engine will shutdown unless you set it back to auto  (white)

Title: Spit fuel management
Post by: dtango on March 20, 2007, 08:27:34 AM

Generally speaking I keep my fuel tank mgmt on auto since it burns off fuel to maintain center of gravity (CG) balance (e.g. left and right wing tanks are equal so that CG isn't shifted laterally to the left or right).  The only caveat is when I'm flying the P-51 with 100% fuel which is when I purposely burn off the aft tank first.

Not sure where the idea on the FW-190 came from.  I see it mentioned on Soda's site.  I wonder if it doesn't have to to do with people equating it to the nuance with the P-51.

To extend the Mustang's range an additional 85 gallon aft fuselage tank was added.  The P-51 was not originally designed with the aft tank in mind.  Because of this loading the aft tank changed the center of gravity and moves it back beyond what the longitudinal (pitch) stability of the aircraft was designed for.  This makes the P-51 longitudinally unstable when there is significant fuel in the aft tank.

I don't think this applies to other aircraft since I'm not aware of other planes having an aft fuselage tank being added after the fact post design.  It appears folks equate that if any plane has an aft tank than you should burn that off first to move the CG forward to avoid aircraft instability.  As far as I know this really only applies for the P-51 because of the reason above.

Tango, XO
412th FS Braunco Mustangs

Title: Spit fuel management
Post by: MiloMorai on March 20, 2007, 02:33:21 PM

Quote

I don't think this applies to other aircraft since I'm not aware of other planes having an aft fuselage tank being added after the fact post design.

The Spit had a rear fuselage tank added after its initial design. The fuselage tank on the 190 was not there when first designed. The Yak9DD had a rear fuselage tank added after its initial design. The 109 did not have a fuselage tank in its initial design.

Read the Spit IX manual and it tells you to burn off fuel in the rear fuselage design due to stability problems. http://www.zenoswarbirdvideos.com/Spitfire9_Manual.html

Title: Spit fuel management
Post by: Scca on March 20, 2007, 02:52:40 PM

My trainer said in the F4U1-A, burn the left wing to empty, the right to 1/8th then the main if no drop tanks are taken.  It helps the roll rate so he says.

Title: Spit fuel management
Post by: BaldEagl on March 20, 2007, 04:51:31 PM

The FW-190-A5 and D9 have an aft and forward tank.  On auto the aft will always burn first.

The 190-A8 and F8 add an aux. tank which becomes the first tank to burn, then aft, then forward.

I think in an earlier version of AH the aft/forward burn may have been reversed, which would coincide with Soda's web pages.  That has since changed.

I always just leave mine on auto no matter what I'm flying.  I could see advantages to roll rates in burning wing tanks first for those that have them but it would seem to be a bit of a pain to have to keep switching them to maintain balance.

Title: Spit fuel management
Post by: dtango on March 20, 2007, 05:00:33 PM

Quote

Originally posted by MiloMorai
The Spit had a rear fuselage tank added after its initial design. The fuselage tank on the 190 was not there when first designed. The Yak9DD had a rear fuselage tank added after its initial design. The 109 did not have a fuselage tank in its initial design.

Read the Spit IX manual and it tells you to burn off fuel in the rear fuselage design due to stability problems. http://www.zenoswarbirdvideos.com/Spitfire9_Manual.html

Ah, I stand corrected then.  The question is how much the CG is moved due to the aft tanks then for each aircraft.  For the Mustang the CG moves aft of the center of lift which means negative static margin = longitudinal instability.  It appears the Spit IX suffers the same issue?

Tango, XO
412th FS Braunco Mustangs

Title: Spit fuel management
Post by: MiloMorai on March 20, 2007, 06:34:26 PM

Quote

Originally posted by dtango
 The question is how much the CG is moved due to the aft tanks then for each aircraft. Tango, XO
412th FS Braunco Mustangs

For that you will have to do some math.

Title: Spit fuel management
Post by: dtango on March 20, 2007, 07:29:56 PM

Yes I know.  I was hoping someone else either had the info or would do the math :D.  Point being having an aft tank doesn't automatically mean that you should burn it first unless you have a reason for doing it e.g. plane instability because cg is shifted behind the neutral point.

Tango, XO
412th FS Braunco Mustangs