SLEC tank, is it possible to drain one without turning the model over?

[martin collins 1]

 I am working on a model that has a SLEC tank in it, the tank is a perfect fit for this plane, the model hasn`t been flown for several years but still has half a tank of fuel in it. Due to the complexity of this plane it cannot be turned upside down to drain the tank once in use, is there a way to modify the piping etc to make it drainable at the end of a days flying.

[Futura57]

My only suggestion is via the fuel feed to the carburetor. If you have access and can temporarily remove it from the carb, use a fuel pump to suck fuel from there, back into a fuel can.

 

I have helis with a T joint in the fuel line before the carburetor. The middle of the T has a stopper on it. I fill and drain the tank from that point with the main needle closed. I just make a mental note of the running position of the needle to open it before starting. 

 

I'm guessing it's one of the square tanks with the two nipples near the top for filling and overflow or exhaust pressurisation, and a centre fuel clunk feed. Great tanks. I use them where ever possible.

 

Edited November 5, 2024 by Futura57

[extra slim]

Which tank?? They do square, round etc

Edited November 5, 2024 by extra slim

[Frank Skilbeck]

Can you pull the line off the carb and use that, another option would be to install a separate drain line and open up the lower connection for the fuel level indicator.

[Futura57]

6 minutes ago, Frank Skilbeck said:

Can you pull the line off the carb and use that, another option would be to install a separate drain line and open up the lower connection for the fuel level indicator.

I concur. I forgot these tanks have the level indicator feature, which I never use.

[Frank Skilbeck]

The other option would be something like the Dubro wiki fill Valve

[Martin Harris - Moderator]

Many people don't like them but I've used them on several models without any problems - my Chipmunk has been using its one for well over 20 years but I notice the price has gone up a bit over that time!

 

They shut off the feed to the carb when the fuelling probe is inserted.

[Ron Gray]

I also use the filler valves but pay a lot less than that for them, MSL

[Futura57]

21 minutes ago, Martin Harris - Moderator said:

Many people don't like them but I've used them on several models without any problems - my Chipmunk has been using its one for well over 20 years but I notice the price has gone up a bit over that time!

 

They shut off the feed to the carb when the fuelling probe is inserted.

Horrible things. I never had one that didn't  leak or cause problems after little use.

[Martin Harris - Moderator]

High nitro fuel or cheaper versions perhaps?   Mine have been totally reliable (that's asking for trouble!) on 10%

[Andy Stephenson]

You might be able to adapt a fuelling system I've used...

The yellow = brass tube inserted to fuel and defuel.

[Nigel R]

Whilst I like these tanks, they are, without adding a fuelling widget, pretty much stuck with draining via removal of fuel line from carb, or turning it upside down.

 

The level indicator isn't at the base of the tank, so you can't empty it completely without tilting the model nose down.

 

[Nigel R]

11 hours ago, Martin Harris - Moderator said:

Many people don't like them but I've used them on several models without any problems - my Chipmunk has been using its one for well over 20 years but I notice the price has gone up a bit over that time!

 

They shut off the feed to the carb when the fuelling probe is inserted.

 

They're not without problems

 

the threaded bit for the clunk is not always well moulded and can thus leak, and it takes a glow plug (!) tap to clean up

 

the spigots are short and/or have no lip - I've had fuel lines come adrift when fuelling up

 

a 2 line install isn't possible, which is ok can as you can blank off the third, but... couldn't one be moulded closed like the level indicator spigots?

 

stating the obvious on this thread perhaps - the two vent/pressure/fill/drain spigots are both at the top...

[extra slim]

On a square SLEC tank, I drill out the bottom right spigot (which is blanked off), put tube on, and a thin piece of tube over it to act as a clamp, or if enough room a very thin tie wrap to help secure, as I too have had tubes slipping off in the past. Then one at the top to the exhaust and blank off the other at the top. I use the bottom right to fill and drain successfully and no need to turn the model over. I only do this when as you, turning the model is a pain etc. As already mentioned the molding on the clunk line into the tank is dreadful, (they really do need to update the tooling as they seem to have got worse over time, so the tooling is slipping out of tolerance/worn), but check it and pressure check it submerged under some warm water... Works for me.

[Martin Harris - Moderator]

 

1 hour ago, Nigel R said:

12 hours ago, Martin Harris - Moderator said:

Many people don't like them but I've used them on several models without any problems

 

They're not without problems

 

the threaded bit for the clunk is not always well moulded and can thus leak, and it takes a glow plug (!) tap to clean up

 

the spigots are short and/or have no lip - I've had fuel lines come adrift when fuelling up

 

I was referring to filler valves but I do agree with your observations on the SLEC tanks.  While they are my usual first choice for builds, they are certainly not without problems but once fitted successfully, are pretty reliable.

 

I routinely run a tap through the thread before attempting to fit the outlet.  I also use a blob of silicone sealant externally on the vent/fill pipes after fitting to help retain them to the tank.

 

The other failing I've encountered on a couple of occasions is leaking at the joint between the coloured and translucent parts - this on new tanks - so always do a pressure test before fitting.

[Martin McIntosh]

Dead easy. Solder three pieces of brass tube to a small piece of copper clad PCB. Block off the centre one with a blob of solder to park the fuel line on when not in use. Connect one to the tank and the other to the carb and mount this under the model. Simply fill and drain through the clunk connection via a U tube between the two. I use this arrangement whenever possible.