Fuel Management

Get tech support for your Lockheed Vega here.
Post Reply
Mgchristy
Posts: 8
Joined: 29 Apr 2018, 00:50

Fuel Management

Post by Mgchristy » 19 Apr 2019, 14:47

Hello Otmar,
Congrats on 0.85! This plane is a real gem...and keeps getting better! I have a question about fuel management in the 3-tank Vega. From the forum post below, I get the impression this might be a bit of an unknown, but hopefully someone might be able to shed some light:

viewtopic.php?f=6&t=827

1) Is fuel burned from the wing tanks first (switching between L & R until almost empty), then the center tank? Or is the center burned first? For a short-range flight, should only the center be filled?
2) When switching tanks, I'm assuming that a brief "hiccup" in the engine is normal due to temporary fuel starvation? Or was there a process to nullify this situation back in the day?

Many thanks in advance!

User avatar
Vitus
Posts: 312
Joined: 17 Jul 2017, 15:19
Location: Görlitz, Germany
Contact:

Re: Fuel Management

Post by Vitus » 19 Apr 2019, 15:29

Thanks man, I'm happy you like the new version!

Please understand that there just is no one answer to the question you asked. Procedures of that time varied from pilot to pilot, or airline to airline. What I write about the fuel management is hence a best practice from my point of view, and you might come up with a different answer to these problems.

The main issue with the fuel is that those fuel gauges were very unreliable, which means you don't have the means to check for 100% how much fuel is left in your tanks. This is even worse for the center tank, since there's no indication whatsoever. For a short hop, this is not an issue. With full tanks, you should get at least one hour of flight out of every tank even if you push the engine a lot. In this case I usually switch between the left and right tanks as soon as I feel that the aircraft leans more towards one side, just to keep it in balance and make the controlling of the ship a bit easier.

If you take her on a long trip, your fuel management becomes more important. In this case I fly on either the port or starboard tank until it is depleted, then switch to the other side. Once both wing tanks are empty I switch over to the center tank and make a note of the time, so I can estimate how much more flight time I got.

I hope that explanation makes some sense, but I'm open for suggestions how to better manage your fuel.

As for your second question: I don't really have an answer for that, and lacking some real-life experience with those old fuel systems. At the moment, the switch doesn't make your engine stutter, unless you turn the valve over the "OFF" position.

The main question is: how quickly does the engine stop when you shut off the fuel valve, even for a brief moment? I don't really have an answer and can only make assumptions based on what I know about the system. My guess is that when shutting off the fuel, the engine should keep running for as long as there is still some fuel left in the carburetor bowls. So when you switch, say from left to right you have a brief moment in which there's a pressure drop in the unmetered fuel supply line to the carburetor. But since the bowls should be half-filled when this happens, the engine should keep running, though will lean out more and more until it either stops or gets the fuel supply restored. What do you think?
Image Wing42 | The Simulation Company

Mgchristy
Posts: 8
Joined: 29 Apr 2018, 00:50

Re: Fuel Management

Post by Mgchristy » 19 Apr 2019, 16:06

Thanks for the input, Otmar! That makes perfect sense. I'd been burning the wings first, while switching between L & R every 15 minutes or so - and leaving the center empty for short flights, but just wanted to make sure I wasn't botching the procedure. I need to remind myself that this is an vintage craft that wasn't necessarily 'flown by the book' like more modern planes - since there really wasn't a 'book' in the first place. It's liberating having that freedom!

I briefly tested now and noticed that the 'hiccup' I mentioned was likely a goof on my part. It seemed to only occur when I either A) had a totally dry empty center tank and took too long switching between the L & R tanks (presumably long enough for the bowl & lines to run dry), or B) accidentally swung the fuel selector the wrong way and passed through the 'OFF' position instead of the center tank. I think I'll leave a few gallons in the center tank at all times just to prevent inadvertent potential cutouts while switching between the wings in the future.

Thanks again!

User avatar
Vitus
Posts: 312
Joined: 17 Jul 2017, 15:19
Location: Görlitz, Germany
Contact:

Re: Fuel Management

Post by Vitus » 19 Apr 2019, 22:08

I think we're all so used to following certain procedures that we quickly forget that it wasn't always like this. So many things were in an experimental stage at the time of the Vega. Many things came down to personal preferences of the pilots. Checklists haven't even been "invented" yet!
Soak that in, and re-live it! Experiment yourself and find out what works for you in this airplane 8-)
Image Wing42 | The Simulation Company

Post Reply