Drifter Belly Tank Plumbing

[seb7701]

Hi all.

 

Having just taken delivery of my new (old) drifter, I am curious about the fuel tank plumbing, which uses the electric fuel pump to transfer fuel from the belly tank to the top tank, which in turn runs up to the carbies (with a squeeze bulb in line for priming).

 

I would have thought it wiser to gravity feed from top tank to belly, then run to carbies through the electric pump to act as a boost pump. Does anyone have any wisdom for me regarding alternate arrangements?

 

The main thought I had is that it would be pointless to have a pump failure and plenty of inaccessible juice in the belly!

 

As always, all thoughts are appreciated!!

 

 

[Patrick Normoyle]

Seb, when I had a small 18L belly tank, I had a similar setup, draw from the top tank and after 1 1/2 hours, pump up the belly tank. Worked fine for years. Now I have 65 L main top tank and no need to pump it, when I go really long distance ( Adelaide to Avalon non stop ), I have a 40 L transfer tank for the back seat and pump it when needed to the main tank. Gives me a good 5 hours with 1 hour reserve.

 

 

[seb7701]

Hi Pat.

 

Yeah, it just struck me as odd, yet I imagine there was a reason they had it set up to pump from lower to upper.

 

It does actually have a gauge for the top tank, so I guess you could keep and eye on the level and pump up from down below. But just doesn't seem wise in the event that the pump fails??

 

More contemplating on the cards I am thinking....

 

 

[c722352]

Mine had the same set up, switched it around so the back tank drained into the belly tank after a pump failure, worked great better than putting down in some field due to fuel starvation.

 

 

[Patrick Normoyle]

Just make sure the lower tank seals air tight at the filling point, and the breather tube is higher than the top tank.

 

 

[seb7701]

Interesting trade-off from what I see now. As has just been pointed out to me, plumbing from the belly to the carbs poses an issue when low on juice in the belly and decending, due to the outlet being at the rear of the tank. Not sure how much needs to be in there to avoid this starvation issue, but 45mins reserve might solve that issue perhaps, which I am guessing is around 12 litres?

 

Option B, with upper tank as the main leaves the issue of inaccessible juice in the event of a transfer pump failure, as I mentioned. Could be a 50/50 toss up??

 

 

[Tex]

Seb, my two cents having given this a lot of consideration as well and was educated by those more experienced than I on different set ups.

 

If it is the 40l belly tank.....The cons are: the ability of the Rotax fuel pump to pump the fuel further from the bottom tank (you have a 503? Not sure on those pumps). On the 582 they have a vacuum pumps so prefer to push than pull. Drawing from the bottom has more unusable fuel (on the 40l tank 8l or so) when in cruise or descent (but you can pump more out in transfer while flying/climbing) . What sort of pump is doing the transfer? The facet type continuously pump so you need the right PSI if it is going to be a boost pump so it doesn't overpower the carb floats... as opposed to the the black round impulse type pumps on original drifters (good luck finding one of those).

 

As I found out you can put a hole in the belly tank taking off and have it empty VERY fast... not good if you draw from there.

 

Having said that I prefer to draw from the bottom tank (with a 582) forget transfers and have a good boost pump working for take of and landing and over tiger country. The Rotax fuel pumps never let me down pumping from the bottom (and Farri has advised he has done so for years as well). Transferring takes planning of course and going down from fuel starvation with 40l on board because of pilot error or pump failure.... but If you have a discernible fuel gauge for the top tank then you can see if the transfer pump is working, so you can check it anyway.

 

If you have that fuel gauge for the top then I would leave yours as is because I tend to think you will be doing lots of local flights? More useable in the top means less weight. If you are going to be doing plenty of big cross country... consider the bottom option.

 

Now more pictures please!!!

 

 

[seb7701]

Sheesh - what to do eh? The transfer option just seems inefficient, but I am thinking perhaps I will leave as is for the time being. It had the black Ecco brand pump (original one 24yrs old) and as luck had it, I jagged the last of the identical units that Repco stocks, in Twba last week, so will slot straight in.

 

As you say, mainly local flights, with the likely one being Roma to Dalby, so easy done on top tank alone. As it happens, it has the original fuel gauge for the top tank, so can even keep and eye and then top it up from the lower.

 

I did manage to track down the post on your fuel line tidy up from a while back, and pleasingly, mine looks more like the after shot than the before, so not much work to do. (Pump failed on way home, as you may have heard...)

 

Only some dodgy shots in the farm shed at moment, but will throw in a few. Still loving that grand total 510hrs on the clock and everything stock and still there, including every warning sticker I think Austflight every come up with, including the one on the fuel tank, which I thought would have been dissolved by spillage by now!

 

Having flown it the other day for the first time, I don't even mind the pull start, given that it is routed to the pilot seat and is really a piece of cake to yank. Just need to investigate some elevator trim and ultimately some mounts for a 582. (I was informed that you can do the inverted 582 thing on the 503 mount, but it does llok a little flimsy, compared to the correct version?)

 

Now just trying to get a chance to zip down and bring it out home.....

 

 

 

 

 

[Patrick Normoyle]

Seb, re the engine swap, yeat you are right, it is just a straight swap, I'd get new rubber mounts ( red bits that sit between the engine mount blocks and tube, the carbies will just pull off one and go on the other ( with adjustments and jetting ), adjust the prop pitch / blade setup, weight and balance and then the paperwork, ground run and make adjustments, test fly and done. I doubt it would be that hard to get the main engine tube replaced but certified, well that's another hurdle ?

 

 

[seb7701]

I know of the odd one, but are there many 582's running around on the inverted mount? Just looks too flimsy compared to the upright version with all it's additional tubes!!

 

 

[Patrick Normoyle]

Mines a Fisher Mk1, I built in 2001, I decided that either could go, the transfer pump or the Rotax pulse pump, I'd rather neither go, but if the Rotax pump goes, the engine will stop real quick, if the transfer pump goes I should still have an hour or more before I run out of fuel. My situation now is that I have 65l in the main tank and for really long flights I have a 40 litre tank for the rear seat that I transfer pump to the main tank, I have a fuel gauge and a sight gauge to confirm the levels of both systems, I have done about 7 long flights without any problems. Maintain your equipment and treat it with respect and it will look after you.

 

 

[Tex]

You will need a 21M Engineering report for the engine swap to be kosha. The inverted 582 (and 532) was the very original set up out of the factory, I heard they went with the upright mount because of plug fouling issue on the 532 and early 582 with the types of plugs used at the time - no real strength or integrity issue; it just related to engine performance. The radiator set up is a bit more complicated.

 

Looks flimsy compared to the upright mount but they were certified that way at one point. The 582 inverted mount root tube were triple sleeved chrome molly.

 

 

[seb7701]

Thanks Tex. agreed, the plug fouling seems to have disappeared with time and technology, but had forgotten about the original inverted 582's until after I posted last night, when I referrd back to photos of a prospective purchase at Yaraka sent to me by Fish a while back. Had an inverted 582, stainless cylindrical fuel tank and huge one piece radiator, all factory fitted!

 

The 503 looks bad enough on the current mount, let alone. 582, but I guess, if it was cert that way, then must be ok. Just need to check out that trile sleeving. I did see somewhere that Kiwi from Boonah did the swap at one point and would be interested to see what was done.

 

If I haben't mention, the 503 fitted at present has only about 150hrs on it and runs really beautifully, so no hurry, but would be ne to be able to car two blokes and decent fuel as well!! I will say that after only having flown in a 503 twice (both with WFish), they are just great one up f climb and cruise.

 

In incidentally, do we know whether any of the lockwood drifter parts fit out beloved Austflights? Have been curious to know just how similar they are, given that all sorts of bits are available from them (assuming Dalby still not happening?)

 

 

[M61A1]

Thanks Tex. agreed, the plug fouling seems to have disappeared with time and technology, but had forgotten about the original inverted 582's until after I posted last night, when I referrd back to photos of a prospective purchase at Yaraka sent to me by Fish a while back. Had an inverted 582, stainless cylindrical fuel tank and huge one piece radiator, all factory fitted!The 503 looks bad enough on the current mount, let alone. 582, but I guess, if it was cert that way, then must be ok. Just need to check out that trile sleeving. I did see somewhere that Kiwi from Boonah did the swap at one point and would be interested to see what was done.

 

If I haben't mention, the 503 fitted at present has only about 150hrs on it and runs really beautifully, so no hurry, but would be ne to be able to car two blokes and decent fuel as well!! I will say that after only having flown in a 503 twice (both with WFish), they are just great one up f climb and cruise.

 

In incidentally, do we know whether any of the lockwood drifter parts fit out beloved Austflights? Have been curious to know just how similar they are, given that all sorts of bits are available from them (assuming Dalby still not happening?)

Lockwoods sell some stuff, I found them handy for plastic bits like batten tips (both ends), saddles and the like. They have an online cattle dog that's not hard to find.

 

 

[farri]

Hi all.Having just taken delivery of my new (old) drifter, I am curious about the fuel tank plumbing, which uses the electric fuel pump to transfer fuel from the belly tank to the top tank, which in turn runs up to the carbies (with a squeeze bulb in line for priming).I would have thought it wiser to gravity feed from top tank to belly, then run to carbies through the electric pump to act as a boost pump. Does anyone have any wisdom for me regarding alternate arrangements? The main thought I had is that it would be pointless to have a pump failure and plenty of inaccessible juice in the belly! As always, all thoughts are appreciated!!

Hi Seb, I thought exactly the same as you when I fitted my Austflight belly tank. If the electric pump never fails and you remember to pump fuel up to the top tank, so it doesn`t run dry, you shouldn`t have a problem.

 

I chose to gravity feed from the top tank to the bottom and draw from the bottom tank. I have a fuel filter before the electric pump, which is 35 cm from the bottom tank and a squeeze bulb half way along the fuel line. I`ve had this setup for 23 years, (well over 2000 hrs) and have never had the slightest problem.

 

Unless I need the extra fuel I only put fuel in the bottom tank. Much easier to fuel up. I`m currently running a 503 DCDI, (inverted) and the standard vacum fuel pump on it has no problem sucking the fuel up. I use the electric pump to prime the carbies before start up, leave it on until I reach a safe height then switch it off and leave it off.

 

Your Choice

 

Frank.

 

 

[seb7701]

Thanks Frank. I had a some conflicting opinions on this, but opted to replicate yours, as I think it is more reliable and one should not really be cruising around with so little juice as to cause starvation on decent. We did ditch the squeeze bulb, but have a small filter between lower tank and pump, then the glass filter a bit South of the vacuum pump.

 

Funnily enough, when going through the documents that came with the plane, found the bulletin from Austflight suggesting the gravity feed type fuel tank setup. If the factory says so, then....

 

Sounds like you're running the same setup with the inverted 503, so beware, some more queries might arise, as 23yrs might be JUST enough time to gain some useful insight!

 

At present, having just discovered the wrong needle jet was fitted, I have regained my smooth running 503, but am now looking at the prop closely (three blade timber) as opposed to the more common four blade fibre, as I'm not sure what sort of climb performance the 503 should be pulling, having mainly flown 582's. Just wish I had the three tubes behind the passenger seat so I could chuck on a 582 and lift some more weight!

 

Thanks again for your thoughts.