600/OS55 Cutting Inverted

[waveydavey]

Have you held the heli upside down and checked what the clunk does?

Is it random anytime during a tank?

It seems to be towards the bottom which said clunk to me. However, after todays cut I re-started on the bench and held it every which way I could to try and identify, apart from leaning out a bit no problem at all. It is only after fitting the 55 and I was wondering whether the clunk line can collapse when the throttle is opened. I'm using Hayes which is quite thin walled.

[squeaky pete]

mine never misses a beat dude, check the exhaust nipple, coz it sounds pressure related, or, could your clunk be to long or to short???? maybe the filter is blocked abit??

[davie]

are you using a fuel magnet or standard clunk what filter you using i have seen it happening with a car type filter when inverted the air trapped in the filter getting sucked into the engine and cutting out clunk too short and crimping when bending to much or too long and hitting the corner or back of tank causing the same thing , crap in the exhaust falling onto the pressure nipple when inverted , just a few more things for you to check

[squeaky pete]

It seems to be towards the bottom which said clunk to me. However, after todays cut I re-started on the bench and held it every which way I could to try and identify, apart from leaning out a bit no problem at all. It is only after fitting the 55 and I was wondering whether the clunk line can collapse when the throttle is opened. I'm using Hayes which is quite thin walled.

if ur clunk is to short then it might be folding and pinching on u in the inverted parts of ur flight

[davie]

great minds pete lol

[squeaky pete]

maybe try a different length clunk, start long as i cant get away with and work ur way shorter, also, u never said if u had a header tank lol

[waveydavey]

I haven't ran a filter for about 2 years since having the problem described above by Davie, but the folding back thing sounds a possibility, as the header was full. If the clunk had pinched it would stop fuel flow. I like the sound of it Pete.

[Mslater]

Running to rich ?

After some new engine bits I've been running the 50 in. The pipe had loads of fuel in it after a few minutes flying, any chance something similar is causing a fluid lock on the return pipe ?

[waveydavey]

Again, doesn't sound daft, my mid is a bit rich.

[coolice]

Hi Dave.

Another thing which might be the case is if the clunk line is too long and when inverted the clink sucks itself to the rear of the tank. From memory the Align tank rear wall is sloped and so with the engine at high revs and fuel demand high it could be the clunk is latching onto the tank wall.

I'm trying to remember if you run a header tank or not now, same check here with its clunk while under high fuel demand allowing its clunk to contact the rear.
If you don't have a header I was also going to say try one to see if this helps.

It's probably not the case here but I have seen engines be less tolerant to tank location in relation to carb fuel nipple, eg. if they are not on the same level and in one orientation fuel has to be drawn up hill perhaps.

Hayes fuel tubing is good stuff but a pain to get the right length as it swells initially.
.

[Eckchaz]

Dave, was the 55 running with the same lines as the 50 before you changed them.. did it cut out then? If it didnt, then none of the too long/short fuel line really applies (unless you done it afterwards )

I cant understand the fuel line kinking when its too short, as the clunk distance is central to the tank.. so the bend on the line inverted is the same as if the heli's upright, so surely the engine would also cut upright?

I also cant get the clunk being too long in the main tank.. becuase if it is, you will see the header tank start emptying inflight as it cant draw the fuel from the main and will do so from the header.

With my little experience.. I'm putting it down to the pressure nipple or the line going to the tank... but then it could make sense that the fuel line is collapsing as you've already mentioned. Just my 2p's worth as alot of you guys are more eperienced than me ..

[davie]

the header tank will only empty if there is a way to get air in if you block the clunk in the main it will stop the flow from the header as its all connected think about it the preashure pipe goes into the main tank to force the fuel into the header if the main tank cant force fuel to the header it forms a vacum thus stopping any fuel flow the header is there to catch bubbles when the main clunk comes out of the fuel during hard 3d type flying nothing more simples

[waveydavey]

It's making more sense that it's the clunk folding back on itself. Before I fitted the 55 the 53 would mis-fire if I changed direction quickly, same clunk tubing type and length. I'll have a fiddle with the clunk line type. Cheers

[rachel]

Hi I had exactly the same problem with my 700, OS 91 powered,
Roll him invirted and the power would slowly die away

New glow plug, then different grades , no 7 , no8 enya no 3, all tried

Out with the tank , new clunk ,added a header tank I tried everything before I found the cause,

Which was ,................................................. ................



I forgot to put it in Idle up !!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Eckchaz]

the header tank will only empty if there is a way to get air in if you block the clunk in the main it will stop the flow from the header as its all connected think about it the preashure pipe goes into the main tank to force the fuel into the header if the main tank cant force fuel to the header it forms a vacum thus stopping any fuel flow the header is there to catch bubbles when the main clunk comes out of the fuel during hard 3d type flying nothing more simples

Read the last few posts http://www.rcheliaddict.co.uk/main-d...ader-tank.html I am trying to find the other original thread.. which was down to the clunk being too long, leaning and cutting out.. thus my thinking behind it about the long clunk suggestion.

Just my 2p's worth as alot of you guys are more eperienced than me ..

As already quoted.. just my 2p but not really, as I read it previously on another thread!