misterneutral

I've been thinking about putting together a long range FPV system using nitro. I've always heard it is abad idea to use a tank too big for your model. This makes sense from an aerodynamic perspective, but would it affect the engine? if the mission objectives of the plane are. "take off. Fly level." - would it be ok?

gene6029

The motor shouldnt know what size tank is feeding it. As long as you have the tank over the CG of the aircraft the plane shouldnt mind either, other than as fuel gets consumed the plane will get lighter.

jaka

Hi!
Why you heard that a big tank is a bad idea isn't because of aerodynamics, it's because of the engine !!!
A too big tank will give engine setting problems. With full tank you have to set the engine so it runs good. Problem is when you have flown for awhile and the fuel level gets lower in the tank, the engine will lean out and stop. This is due to the fuel pressure is getting lower and lower to the carb, the more the engine uses up fuel. That's why it's important not too use too big tanks.

It's another thing if you used a pump, then you whould not have these problems.

KW_Counter

The reason we balance the plane dry is when the fuel in introduced the plane is nose heavy.
Though the plane is now out of balance at least it is nose heavy rather than tail heavy.
As the fuel is used the plane returns to proper balance.
A bigger tank may make the plane excessively nose heavy - not good.
It will be very difficult to fly - but again, nose heavy is better.

Placing the fuel tank over the CG will help this problem but may cause others.
The engines we use don't have great fuel drawing power.
Often times the CG is to far away to have an efficient draw and may cause dead sticks.
Fuel pumps are available for some engines. I haven't ever used one so won't comment.

The is much info available here on RC Universe - happy reading.

Good Luck,
KW_Counter

jetmech05

Yep CG and head pressure

Gray Beard

My Feedback: (-1)

Jaka and KW stated the reasons. The fix is a pumped engine and you can install the fuel tank any place you like, even centered over the CG. I have several pumpers, the OS has a pump that sucks the fuel like you sucking through a straw. They use an open vent on the tank. Most of my glow engines are YS and they are a closed system that pump about 7 pounds of pressure into your tank. There is more to them then that but that should give you the idea. Both systems work very well so it's a choice what one you use. I have them both but prefer the YS.

pimmnz

Or you could simply use exhaust pressure and a chicken hopper tank.
Evan, WB #12.

nitrohunter

so i am reading this where can you get that fuel pump to put a bigger size tank?

JollyPopper

My Feedback: (6)

Perry Pumps makes and sells pumps that you can bolt onto the rear of an existing engine. I've never used one so I can't testify as to how well they work.

daveopam

My Feedback: (9)

We have done cross country events at our field. We just mount two extra tanks to the outside of the plane and hook the fuel lines up in series. It's not pretty or aerodynamic, but it works fine. the tank in the fuse is the last one to empty, so it stays full until the other two are empty.

david

nitrohunter

so do you have any pictures showing how this installation looks overall? Thanks

sebo

I don't know if it makes any difference, but I use multiple (2) tanks in series to accomodate more fuel...works for me.

RC_Fanatic

My Feedback: (1)

I use one on my Focus Sport with an OS 120 2S and the tank on the CG. Hard to start the first time in a day but runs steady from full to empty, going straight up or on the level.

daveopam

My Feedback: (9)

I don't have any pics. But we just rubber band mount the extra tanks at the CG. Either to the fuse or the wing. On a high wing you can hardly see them. The line from your main tank stays on the carb. Then run a line from the muffler to the pressure line on the left tank. The run a line from the clunk line on the left tank to pressure line on the right tank. Then run a line from the clunk line of the right tank to the pressure line on the main tank. It is easier than it sounds. You fuel it up just like it had one tank. Pump into the carb line until it spits out of the muffler line.

David