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Bailey V5 - help wanted in setting up competition bottle


henryglasse

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Hi all,

I want to set up a gravity feed comp bottle on my Bailey V5 as I am going to have a go again at the Nationals this year and it's also a safety benefit as it gives you ample warning of running out of fuel.

I set it up so fuel pump feeds fuel into bottle, fuel gravity feeds to carb and excess fuel feeds back into main tank through return pipe T connected into the normal return pipe. This is how it was set up on my old Bailey 175 (V3?) but it doesn't seem to work correctly with the v5. The bottle fills up fine and the excess flows back to the tank fine. The carb gets fuel ok to through and extra small fuel filter. some small amounts of air soon get sucked through when the engine revs are increased and clear. Engine runs ok on tickover but coughs and splutters at higher revs as though there is too much air going in. I wondered whether it needs a different setup of jets or something to supply fuel by gravity rather than direct from fuel pump? I would ask PB but he's on hols.  I refitted the carb the normal way and its fine and runs beautifully as usual.

Any help gratefully received.

 

Cheers, Henry

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Comp bottles are a royal pain in the arse and best left off unless you really need them.. You won't need them for the UK comps as we do not use weighed out fuel.. it's only if your going to go to international comps where they will give you 1-2kg of fuel so a comp bottle is vital.. 

There are many ways to set up a comp bottle and depending on your engine/fuel set up will change the type you use.. 

My advice would be do not use one as they cause more land outs due to leaks etc than running out of fuel does...  I can not remember how my V5 comp bottle was set up, but it works the same or has the same fuel set up as my 250...  

You may find you have a few issues with your set up.... One over pressurization of the bottle or two you have the bottle too high up both causing flooding.. Having the pump before the bottle will give you a pressurized Bottle system where having the pump after will give a vacuum system  first system can cause fuel leaks if your bottle is not watertight the other air leak..  

try lowering your bottle.. My V5 bottle was fixed to the two cage spars, my 250 is at shoulder height on the chassis.. by lowering it you rule out gravity causing the issue, or try just using the bottle with the cap open to rule out pressure or removing the fuel pump pipe, if neither of these work you need to try a new system altogether..   But i have always used the hernia style systems..

Photo of my comp bottle, not very good photo but its all i have, 

43089072795_62fc22b533_z.jpg1111comp by mark.morgan07, on Flickr

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My system goes from tank to bottle and then to the primer bulb to pump then carb...The  carb feed pipe is fitted below the cap and the clunk goes to the base of the bottle..   The return system is not touched and is the standard system.. You will have to manually fill the Comp bottle before flying, Make sure it is FULL and no air at all...

If you have a pressure/gravity issue that i think your suffering with try having the pump after the bottle.   Pressure will overcome the low end jet causing rough running..  

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Mark,

Thanks for your advice. Yes, maybe

main tank - primer bulb - comp bottle - fuel pump - carb

is the way ahead. I would have to remove the venting I guess as the fuel pump would have to suck the fuel up to the bottle, rather than pumping into the bottle.. But any air leaks would render it all useless!

or what if the bottle was pressurised? ie..

main tank - primer - fuel pump - bottle - with no venting or return from the bottle - carb?

At the moment it is

main tank - primer bulb - fuel pump - comp bottle - carb (with gravity feed and vented return to the main tank).

or perhaps I should just wait until PB gets back from his hols!

best, Henry

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24 minutes ago, henryglasse said:

Mark,

Thanks for your advice. Yes, maybe

main tank - primer bulb - comp bottle - fuel pump - carb

is the way ahead. I would have to remove the venting I guess as the fuel pump would have to suck the fuel up to the bottle, rather than pumping into the bottle.. But any air leaks would render it all useless!

or what if the bottle was pressurised? ie..

main tank - primer - fuel pump - bottle - with no venting or return from the bottle - carb?

At the moment it is

main tank - primer bulb - fuel pump - comp bottle - carb (with gravity feed and vented return to the main tank).

or perhaps I should just wait until PB gets back from his hols!

best, Henry

I have never used venting for the Comp bottle, people do as it means you can do multiple tests during one flight but the more connections you have the more issues your likely to get..

(main tank - primer bulb - comp bottle - fuel pump - carb) NO... Main tank, Comp bottle in, Comp bottle out to primer, Primer to Pump pump to carb 

 

(At the moment it is

main tank - primer bulb - fuel pump - comp bottle - carb (with gravity feed and vented return to the main tank).)

You have both Gravity and pressure thats is most likely causing it to overcome the bottom end jet.. even if you remove gravity you will still have Pressure and will covero come the Bottom end jet.. Flooding happens on a hot summers day with a standard V5 or V5S if you leave it in the sun for to long... 

Try tank-bottle-bulb-pump-carb. The pump is actually getting a much easier life than it would be sucking the fuel up from the tank so this has no problem. you just need to make sure your using good quality fittings and new tygon 4.8mm fuel tubbing.. Also use two Quick breaks so you can remove the fuel bottle from the system in a few seconds when you do not need it for a task and only use it when your on an eco task. This cuts out any chance of landing out due to a failure of any sort in the system..  

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