I am in the early stages of a 4 engine plane construction. My question concerns fuel systems. I am planning on using 4 OS 40s. is it better to run 1 tank or 2 or 4.
How do you set-up the pressure and fuel lines?
Throttles are a piece of cake, ( I plane on using a seperate TX and RX for them and 4 servos)
Thanks
Dan

Dan:

I've never tried feeding four engines from a single tank, but more than once I've fed two.

Some things that have not worked for me on multi engine feed from a single tank:

Both engines fed from a single fuel pickup/clunk using a tee.
Header tanks. Waste of time and effort - the engine still has to draw the fuel from the main tank.
Muffler pressure. In maneuvers the high engine goes lean and the low engine goes rich, both quit running.
Plain suction feed.

This way works:

Separate fuel pickup/clunk for each engine,
--- AND ---
Crankcase pressure with check valves and Cline (or similar) regulators.
--- OR ---
A Perry fuel pump on each engine. (This worked best of all.)

Hope this helps. Really think everybody with three or more engines is using a tank for each engine.

Bill.

I suggest that if you are soley relying on muffler pressure to get fuel to you engine you use one tank per engine, for a couple of reasons:
1. If one engine quits then fuel tank pressure will exitout the stopped engines muffler line
2. As soon as you start running more than about 8" of fuel tubing you need a good amount of backpressure or a pump to get fuel to engine.

The best option is to run 4 tanks. Bill is again right about the pumps, they will keep constant feed to all engines no matter what the models attitude.

I would be carefull about check valves though, some engines don't like them at all. They seem to be ok at higher RPM, but hold the pressure at idle and flood out the engine.

Lets see some photos of the 4 engine job!!!
Hans

See my update on the C130 for 4 engines. I used individual tanks and treated each engine as individual. The engines were not set with mixture to attempt to get the same speed. I set the throttle barrel full open on each engine with a single servo / engine. Linkage was identical set up for each engine. Then the mixture was set to get reliable performance for the individual engine, this might result in a 400 rpm difference, but I went for reliable flying vs. peak. My reco. is use slightly larger engines so you will have the power. Mine is underpowered built [] as designed but does fly. Jim

I must totally agree with William Robinson.
I have made most of the mistakes in this area. Best solution is to use separate tanks for each engine.
Reliability must be the most imporant concern.
Good Luck,
Twinman
PS Never try dual muffler pressure to one tank as cautioned by canadianjosh
......Major problem......only one worse.......tee's.

Sorry guys no pics. I said I was in the early stages I wasn't kidding.
I will come up with som pics as soon as I can though.
I plan on buying a kit from Conachen Avaition.
www.conachenaircraft.com
real soon
It will be a Lanchaster Bomber
I'll let you know howit goes
Thanks for the input