BAC 1-11 temperature limiter and engine performance...

jonesey2k · Post by **jonesey2k** » 12 Oct 2006, 19:15

I must admit this caught me out too. I had to continue my flight with only one engine going

DispatchDragon · Post by **DispatchDragon** » 12 Oct 2006, 19:17

Curious as to who operated MAN-CFU in a 1-11 thats one hell of a flog - we did LTN-CFU but reduced the pax load from 89 to 79 and then ran the risk of a tech stop in Brindisi

Leif

Macs · Post by **Macs** » 13 Oct 2006, 00:16

DispatchDragon wrote:And there lies the rub Macs - short runway more flap - as Chris says use the limiters and fly V2 +10 on reduced power and allow the aircraft accelerate at a "reasonable rate of climb" (in some cases terrain allowing
less than 1000 fpm) You didnt mention which model 1-11 - I have been running the 400 series out of fairly short runways - 6500 foot isnt that short for the 1-11 although 32C is bloody hot - DanAir operated 400s from Luton when it was only 6700 foot and they performed much better than the 500s - and they operated at MTOW until about 29/30C then
started becoming restrictive. My suggestion is use balanced power, 15 flap and fly the Vspeeds given and unless you have rising terrain - climb slowly.

Cheers

Leif

I used the 400 Leif,
Regards,
Macs

Macs · Post by **Macs** » 13 Oct 2006, 00:33

MALTBY D wrote:The weight makes a lot of difference to takoff & climb performance.

I've been flying the 1-11s with the CBFS va & it's been quite a surprise how light they usually are for takeoff.
I'm usually doing 500-800nm trips & performance is very good. It's quite a slow cruiser though.
On my typical routes, it never needs any fuel in the centre tank & it's quite rare for the wings to be more than half full. It goes all the better for it. :dance:

DM

Dave,
I use the old rule of thumb of 3000 kg/hr for fuel planning, but I noticed in the last flight it was more like 2000 kg/hr, hence the high fuel load for a 800 nm trip. I agree that the initial climb rate is very low, but I woudl rather have it reaistic than not. Please do not get rid of the failure mode simulation, I have seen this in other packages like Fraser Mckay's Visocunt and Vanguard, and think it makes flying more fun, as well as force you to fly right

regards,
Macs

jonesey2k · Post by **jonesey2k** » 13 Oct 2006, 02:30

Agreed. I like having things go blammo when you dont do it right.

flugkapitan · Post by **flugkapitan** » 13 Oct 2006, 03:37

Hi all,

I was reading the above posts and noticed Mr. Maltby mentioned only using the wing tanks for short flights...which are are the majority of the of the flights I fly in FS.

I loaded a 1-11 400 (the latest version) for a quick 336nm flight. I figured I'd try just using the wing tanks with reduced gallons. I went into the fuel menu in FS and set the quantity of the centre tank to 0, and about 60% in each wing tank. Exited the menu to the aircraft.

The engines promply quit running and spooled down. :shock:

I've been through the manual (really, I have!), and can't figure out how to set the switches for only drawing off the wing tanks.

Any help will be greatly appreciated.

Regards,
Scott
KJMS (or thereabouts)

DispatchDragon · Post by **DispatchDragon** » 13 Oct 2006, 04:28

Scott

How did you have the fuel panel on the overhead set up? - usually
when Im running in Flynet with wingtanks only I have the crossfeed
valve (bottom center) on the panel open and all pumps operating
you will get an amaber tranfer light on at the top of the panel - which
once confirmed maybe be extingushed by pushing it in. Also Im not
100% sure (David will be able to confirm or deny it) but once the
engines are online and running - you need to shut the APU down
as Im not sure if DM made it as a 3 engine which would mean its still
sucking fuel. usually I shut the APU down at the end of the runway
before takeoff (which was SOP with the real 1-11s I used to work with)

Hope this helps somewhat

Leif

Macs · Post by **Macs** » 13 Oct 2006, 04:28

flugkapitan wrote:Hi all,

I was reading the above posts and noticed Mr. Maltby mentioned only using the wing tanks for short flights...which are are the majority of the of the flights I fly in FS.

I loaded a 1-11 400 (the latest version) for a quick 336nm flight. I figured I'd try just using the wing tanks with reduced gallons. I went into the fuel menu in FS and set the quantity of the centre tank to 0, and about 60% in each wing tank. Exited the menu to the aircraft.

The engines promply quit running and spooled down. :shock:

I've been through the manual (really, I have!), and can't figure out how to set the switches for only drawing off the wing tanks.

Any help will be greatly appreciated.

Regards,
Scott
KJMS (or thereabouts)

Scott,
Without knowing exactly what the problem is, I venture to say you have not turned the fuel boost pumps on and/or the LP fuel valves. The engines are only supposed to feed through the wing tanks directly as I understand (and as shown in the diagram for the fuel system in the OH panel). If the engines quit (with sufficient fuel remaining on the wing tanks), it must be beacause some path or pressure to the engines was lost, like shutting off a valve (LP) or turning a pump off (Boost pump). Shutting down the transfer valves for the center tank does not cut the supply to the engines. In fact the takeoff checklist has one item for turning them off before takeoff. It coudl be also you accidentally clicked on the "CS" button, which turns them all off. This can be easily taken care of by following the checklists, although I don't mean you hadn't. Hope this helps,
regards,
Macs

flugkapitan · Post by **flugkapitan** » 13 Oct 2006, 04:48

Mac & Leif,

Thanks for the replies. I had posted the following before I saw your post. I did have all the switches, pumps, Lp's on when I posted my original question, however I had neglected the vital crossfeed switch!

You can probably disregard the previous transmission :redface:

After landing at KBNA (lovely flight by the way, what a sweet little airplane) in the AA 1-11 400, I opened the crossfeed valve, and shut down the centre transfer valves and pumps.

The engines kept running.

:dance:

So, I guess if one were to fly with fuel in the centre and wing tanks, you have to carefully monitor the level of fuel in the centre, and when it approaches 0% , open the crossfeed and switch off the centre pumps?

Regards,
Scott
KJMS (or thereabouts

Post by **MALTBY D** » 13 Oct 2006, 12:06

You've stumbled on a peculiarity of the model.
If you have the pumps, valves & crossfeed set normally, setting the centre tank level down to zero will always result in a fuel cut off in FS.

The fuel system works quite realistically on the 1-11 model, but it's an illusion.
The real thing only ever feeds the engines directly from the wing tanks, but pumps refill the wings from the centre tank.
So under normal running, although the engines take fuel directly from the wing tanks, only the centre tank empties.
To simulate this, the model will actually take fuel directly from the centre tank if it has any fuel. So, suddenly empty the centre tank & the engines cut in FS.
There is some XML code that secretly switches the FS fuel feed from the centre tank when it's near empty. But when the level is suddenly set to zero it can't switch the supply quickly enough to avoid the engines cutting out. It's only a microsecond of fuel starvation, but that's all it takes.

So, if you want to empty the centre tank it's best to leave a small amount (2%) in there & let it drain itself.
Under normal running there's never any need to open the crossfeed when the centre tank runs dry.
Or, if you're on the ground you can just start up again without touching the fuel system.
Nearly every 1-11 flight I do with the CBFS va starts with a fuel cut off.

DM

Classic British Flight Sim

BAC 1-11 temperature limiter and engine performance...

Fuel mgmt question

Re: Fuel mgmt question