Fuel magnet or header tank for 700

[DT39]

As the title what are you using on your 700 fuel magnet or header tank.
Just about to fit fuel magnet and see how I get on with that but just thought it would be nice to see what most are using.

[tonystevens]

Im using a header and bubless clunk on my 700 but only because im running an OS 91, i use a magnet on the Aurora with a YS 91 sr and will do the same once ive got a YS on the 700

[Farmer Giles]

at the rate a 700 drinks I would imagine you'd want as much fuel on board as possible...

for the record I changed to header and clunk on my 600 from the fuel magnet that was fitted when I bought as the benefits of having more fuel onboard far outway the weight issue at my level.

I once missed my TX alarm and when I thought 'I've been in the air a long time' I was 1/3 into the header...

no brainer for me..

[SRH990]

I added a header tank to my 700 shortly after build as I kept running out of fuel! At this point I was running an OS91-SZH but with an OMI modified carb running on crankcase pressure and it vibrated pretty badly, causing significant foaming in the tank (think washing machine on spin cycle!). After adding the header tank I ran out of fuel much less often but noticed I had almost a quarter tank of air in the header due to the foaming in the main tank.

Fast forward a year or so and I now have an OS91-HZ fitted plus a flybarless head and Align 3G system. I get virtually no foaming in the tank and I've gone from around 8:30mins on the timer for the previous setup to aroun 11:00mins, it appears that the flybarless setup certainly has a marked affect upon fuel consumption, both in nitro & electric helis so if I was starting again, with this setup, I'd probably not bother with the header tank.

[Si Goodchild]

Header tank. I originally fitted a fuel magnet but it broke up and ceased to work properly causing a couple of forced autos before I worked out what was going on. I think this happened because I kept the tank empty between flying sessions and the exhaust gasses were corrosive to the fuel magnet.

I fitted a header tank (Raptor 50 unit) with a home-made stand-off on the engine mount and junked the fuel magnet in favour of the standard clunk. Never been a problem since and I too have managed to run the main tank dry and eat in to the header tank before landing. There's a fair bit of correspondence on this subject on Helifreak and also on this forum after I initiated the same question.

Si G

[lex7919]

I run a header on my 600, With a OS bubbless clunk which i put on a very short fuel line so the clunk is always in the centre of the header tank, Works perfect.
I just really dont like the idea of the line been out of the fuel at any time whether its got a magnet or not.

[PsiLo]

Header here, ran a fuel magnet on the N9 with OS 91SX C-Spec, foam disintegrated mid flight causing a lean run. Then the replacement disintegrated within 2 months also, even though it was always stored with full tank! I don't think the fuel magnets like 30% Optifuel!

[Mat the splat]

Simples!!!
Both
OS bubbleless clunk (71531010)

Mat W

[DT39]

Re: Fuel magnet or header tank for 700

Oh now he pipes up now I already got fuel magnet yesterday lol.

Simples!!!
Both
OS bubbleless clunk (71531010)

Mat W

[Farmer Giles]

Someone's mentioned it already but I did not like having to leave fuel in the tank to preserve the fuel magnet and having to remember to re-fill straight after landing even if you're not flying again for an hour..

2p

[LipolyGone]

Bubbless OS clunk and header here too.
Running a ys 91st I found the fuel foaming
had me doing forced autos halfway through the
main tank. Thats why I fitted the os clunk
and now I get reliable runs right on to the header.

[sacko]

OMI fuel magnet here

When you have half a tank of fuel left, I found that air was just being sucked into the header, which kind of defeats the object doesnt it?

[J-S-Q]

OMI fuel magnet here

When you have half a tank of fuel left, I found that air was just being sucked into the header, which kind of defeats the object doesnt it?

That's true but I've always thought of a header tank as a 'bubble trap' that catches the air which otherwise would have gone into the engine.

[sacko]

..but it would still go from the header into the engine.

[J-S-Q]

..but it would still go from the header into the engine.

Not all of it would reach the engine though -if the header tank has an air pocket in it at the end of a flight (like mine often did when I ran one) then that air has been 'captured' rather than been passed on to the engine. I'm not necessarily saying all the air is captured but I reckon a decent majority of it is.