Slec fuel tanks

[Phil Claridge]

i have just fitted one to a wot four  the clunk pipe is avery small bore and flimsey. why cant they make the bung hole large enough to take a more standard size fuel plus larger clunk with larger bore pipe, the would be less chance of the clunk sticking up the front on less than perfect arrivals

[David Martin 2]

I had isues with my Slec tank in my Acrowot Phil, the clunk during aeros would bend round and get trapped in a top corner, cutting the engine.

Changed to a Kaven tank and had no problems in the last 6 months.

I tried different flexi tubing and adjusted the length a tad but still no joy. The replacement tank cost little and provided an instant fix.

David 

[Tim Mackey]

I always cut the internal clunk tube, and insert a length of rigid plastic tube ( snake outer or similar is fine ) leaving each end with a short bit of flexi silicon tube. This allows the clunk to roam around the tank as it needs to, but prevents it from folding over on itself.

[David Martin 2]

He's a diamond Phil, could have saved myself a few quid there...

 Odd thing was, I could lift the nose of the model and shake it like mad without it freeing, take the effort to remove the tank and it falls down practically on it's own..!

 Ho Humm...

[Tim Mackey]

Ah, the old sods law eh

[Bob Cotsford]

I suspect this is the problem I've got on my flair Hooligan, ran fine until it took on an oak tree (which lost, incidentaly).  Now it will only run half a tank through, and then only if the nose is level, not really how a Hooli should be flown, is it?  I'm tempted to dig the slec tank out and replace it with the original round bottle type tank.  Just means removing the switch mounting plate which is glued in across the fuselage.  As you said David, I've shaken it like mad, done everything short of swinging it round my head by the prop but it still won't come free.

[fly-navy]

 Timbo.read hero,went flying today only took acro,flew perfect last week,everyone a greaser(modest as well)today could not get the bu**er to run,squirt in carb ,would run on that,then die,knew it was tank prob.but believed i was not destined to fly today so came home,will take it out sat.and do Timbo,s mod

[David Martin 2]

I tend to steer clear of round tanks now Bob, they tend to twist and do funny things from the sunken breather pipes at fill up time..i.e tell you the tank is full when it's only 1/2 really and everthing goes quiet about 5 minutes before it should in the air..!

 That's why I have rectangular ones now with nice rounded corners..stays upright but the clunk can't get trapped anywhere....(yet...!)

Sailor, I'm sure you would have heard it rattling differently if the clunk had come adrift, but it sounds like your fuel pick up line is sticking out horizontal mate..!

 Best just prop hang it.

[Phil Claridge]

ive just remembered reading somewhere that you can stretch an old biro spring and wrap it round the clunk pipe to stiffen it ithink i will give this a try

[fly-navy]

Took tank out of acro yesterday,like David said,as soon as it was out down dropped "Clunk",b*gger.Done Timbos mod,sort of damp ,ahem,today snowing and sleet now in fact,wait until in the week to see if it has cured it,do some gentle batics and act my age.

[Tim Mackey]

It could still double over on itself?

[Bob Cotsford]

round tanks - tape a length of 1/2 or 3/4 " triangular balsa to the tank, it won't twist.  I've even made triangular notches in the formers to match the triangular section - never had a problem with a round tank and fuel feeds, unlike SLEC squares.  I can't help wondering whether that's because the SLEC clunks are just too long?

[David Martin 2]

I must be simple Bob...didn't think of that during my 10 years of hassle..!

I cured the problem in the end by taking up slope soaring.

[Bob Cotsford]

just another good idea filched from the old hints'n'tips page years ago.

[Peter Eve]

I've just had a problem with my Evolution 46 in a Tutor 40.  Inadvisedly, as it would now appear, I lengthened the fuel tube to give a smoother run and less risk of a kink.  From that time on it gradually ran less reliably until, in the end, I couldn't get full throttle to hold for more than 15 seconds before it died.  An old hand in the shop said the run was too long and shortening was like a miracle cure but why did it gradually get worse?  He says he doesn't trust the plastic bung pipes and that i should fit brass ones - with a different tank if the bung is not compatible.  On the way through trying to solve this problem someone suggested trying the engine with the tank above the fuselage - I did and everything was fine.  The tank problem was obviously only there when drawing the fuel "uphill".

 Any ideas on this one?

Pete 

[Bob Cotsford]

vibration causing the fuel to foam , or an air leak in the excess tubing causing loss of suction, hence it only runs with the tank set high so the fuel syphons downhill.