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Plumbing Two tanks in my Hawk

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Plumbing Two tanks in my Hawk

Old 02-13-2007, 03:14 PM
  #26  
jason
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Default RE: Plumbing Two tanks in my Hawk


ORIGINAL: mick15


Sorry to disagree with Jason but, if the tanks are “Teed” one will always drain first leading to air and fuel to be drawn into the header. If the tanks are in series they WILL drain in turn.

m

hey Mick,

sorry to disagree with you but I can't see and advantage of plumbing identical twin tanks in series in a AMD hawk... The guy is using a Fadec ECU and if he uses the tanks in series he could find the idle is high on landing due to a freer fuel flow. I would not be keen on having 24oz on one side of the fuse and nothing on the other half way through the flight. If you use equal length pipes and ensure the pipes are the same diameter with no burrs the tanks will both fill and drain at the same rate. I had twin 24 oz tanks in parallel with a uat in my AMD hawk and it was perfect.

Jason
Old 02-13-2007, 03:21 PM
  #27  
Vincent
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Default RE: Plumbing Two tanks in my Hawk

I like series because when you fill each tank is completely full and when they empty each one drains out completely. Also the first or even second tank in a series will be full for most of the flight not allowing for any air to be brought into the UAT.

V..
Old 02-13-2007, 03:23 PM
  #28  
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Default RE: Plumbing Two tanks in my Hawk


ORIGINAL: L Turner

Dennis,

On my 'Green' MW-44 powered JHH Sabre I have tried both parallel and series tanks and could not detect any lateral balance shift emptying first the R and then L tank when in series. I have been very sastisfied with simply two tanks in series, the one closest to the fuel pump with the felt clunk, a regular clunk on the other. Simple seems best.
I have used a UAT (in my Facet) and they are not without problems. There is risk of air entry whenever you fuel up or whenever you open the fuel system. It is hard to detect bubbles inside the inner woven plastic bag: you should take them out, hold the UAT upright and vigorously shake or vibrate it with the turbine running to be only relatively sure there are no bubbles in the bag. The UAT should always remain full with 4 oz of unusable fuel, they are somewhat heavy and require large bore 5 mm tubing towards the fuel pump inlet.

With 48 oz of fuel, you should regularly get nice flying times, with a reserve of 40-50% (9.6-12 oz) in the tank closest to the fuel pump. You will be able to consistently fly to that reserve fuel level with the Wren supplied Felt clunk, without fear of flame out even with one extra go-arround. Make sure the felt clunk moves easily, extending about 3/4 ths towards the back of the tank, and angle that last tank slightly upwards towards the nose. Use gasoline compatable stoppers and run the 1/8 yellow tygon tubing between the tanks. I use solid wire to double safety wrap the tygon to metal tank tubing. I use Sullivan metal tank caps, but they are probably not necessary. You'll want a fill line with a fuel dot type plug or bung running to the 3rd hole of the closest tank, and an accessable vent for other tank furthest away. When you fuel up, attach an off-board overflow tank to that vent which can be disconnected after turbine starting, so you always roll out with the same amount of fuel. The biggest risk to causing a hot 'flaming' start is to forget to close the manual shut off valve between the fuel pump and turbine. The manual fuel cut off valve should be last on before start, and first off after turbine shut down.

I recommend setting up your Gold on the bench, with the fuel system as described, and trying some familiarization runs before you try it in your Hawk. Its fun!

Larry Turner


That is an excellent response and very helpfull indeed Thanks Larry

Dennis
Old 02-13-2007, 03:37 PM
  #29  
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Default RE: Plumbing Two tanks in my Hawk


ORIGINAL: mick15


QED Dennis, what Ive been saying all along.

m

By the way do you fly at Honington?
I fly at Raydon in Suffolk and this is my first Turbine. A couple of chaps from our club Steve and Roger I think fly at Honington.........

I think I have just about sussed the plumbing thing
Old 02-13-2007, 06:12 PM
  #30  
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Default RE: Plumbing Two tanks in my Hawk


ORIGINAL: mick15

Alrighty Dennis,

I recommend the following:


6. you better buy a UAT and find a spot for it, if you don't then you’re asking for trouble

Just to add MORE confusion I have NEVER had a flameout using a simple, geometrically centered pickup, in a simple header tank mostly using old JPX oil tanks ! What am I doing wrong ?

I have had a couple of flameouts with UATs not being totally purged . As for purging them by shaking the model with the engine running, foget that ! Much easier and safer to do it by using the prime function on the ECU/GSU to run fuel through the system and purge it ! Properly purged a UAT works very well indeed, perfectly, but so does a simple hopper tank !

Regards, David Gladwin
Old 02-13-2007, 06:40 PM
  #31  
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Default RE: Plumbing Two tanks in my Hawk

In 129 flights on my Rookie II I've only had one flame out. It was due to the fact that the quick disconnect fitting plunger on the end of the line to fuel the fuel system was not seated properly. Tests confirmed it on the ground. I was surprised how far down the Kero level got before it flamed out. I think if you use a hopper like tank, why not make it the BVM UAT or equivalent on the market that is known to work for a first time turbine modeler. I just bought another BVM UAT for my second jet. I could have made one myself, but its just easier to buy the finished product and be assured it will work without a lot of time wasted in testing it. Ken
Old 02-13-2007, 06:50 PM
  #32  
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Default RE: Plumbing Two tanks in my Hawk

Ken,

The point is that the simple hopper is VERY quick to make AND requires absolutely no purging or maintenance just fit and forget. It cannot go wrong and there are absolutely NO operating procedures required, it is automatically self purging, and it works first time EVERY time, all the time. !
Regards, David Gladwin.
Old 02-13-2007, 07:00 PM
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Default RE: Plumbing Two tanks in my Hawk

I agree with that, but what makes me nervous is the fact that the clunk needs to follow the fuel around. Depending on the shape you use, it could get caught up on the side wall and you'll be sucking air straight to the fuel pump. Ken
Old 02-13-2007, 07:56 PM
  #34  
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Default RE: Plumbing Two tanks in my Hawk

Ken,

The point is that the simple hopper is VERY quick to make AND requires absolutely no purging or maintenance just fit and forget. It cannot go wrong and there are absolutely NO operating procedures required, it is automatically self purging, and it works first time EVERY time, all the time. !
Regards, David Gladwin.
Old 02-14-2007, 04:07 AM
  #35  
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Default RE: Plumbing Two tanks in my Hawk

Ken

I think you have missed the point that David made earlier. The pick up in the hopper tank is a rigid pipe which is centred in the hopper tank, it is always in the centre of the tank and as the hopper is always full (unless you run out of fuel!) it is always passing fuel to the pump. I have adopted this system after reading one of David's articles in RCJI and it has ALWAYS worked for me.

John
Old 02-14-2007, 06:43 AM
  #36  
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Default RE: Plumbing Two tanks in my Hawk

Big Plumbs,

so the moral of the story is that there is more than one way to skin a cat.


I think the best thing for you to do is go to a jet meeting and sit back for half a day and see who's planes are reliable and are always in the air, then poke your nose inside and see how its done.

Jason
Old 02-14-2007, 12:23 PM
  #37  
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Default RE: Plumbing Two tanks in my Hawk

I agree Jason................. Poor cat I say. I have learnt a lot here now on the basic plumbing I just need to decide on the hopper/header. The only problem is there is very little space left in the Hawk to fit one after you have shoe horned all the other items in

Dennis
Old 02-14-2007, 01:42 PM
  #38  
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Default RE: Plumbing Two tanks in my Hawk


ORIGINAL: bigplumbs

I agree Jason................. Poor cat I say. I have learnt a lot here now on the basic plumbing I just need to decide on the hopper/header. The only problem is there is very little space left in the Hawk to fit one after you have shoe horned all the other items in

Dennis

Dennis,

a good place for you header tank is at the front right hand side. It's a easy job to modifie the large hole in the woodwork to accept a UAT size bottle and most of the bottle is under the tray which helps on space. It also keeps the weight forward as you will need that.

jason
Old 02-15-2007, 03:00 AM
  #39  
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Default RE: Plumbing Two tanks in my Hawk

I may or may not go with a header tank but I am not going to use a UAT. From what I can gleen the UAT seems a lot of trouble and if you go for a series installation not necessary. I think this will be my selection from the warious opinions here and elsewhere

Dennis
Old 02-15-2007, 03:21 AM
  #40  
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Default RE: Plumbing Two tanks in my Hawk

In my son's Hawk i just used a 1.25 Litre lemonade bottle and a 8 oz header in the nose with a central pick up (solid pipe with a felt clunk on the end) as there is a need for some nose weight in this plane it might as well be a large hopper! i placed the tank out of the way under the ply plate as far forward as posible

Dave Stephens
Old 09-23-2022, 03:59 AM
  #41  
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Default

My goodness
the guy asked for some sketches, drawings or photos surley someone could help with that.
A picture paints a thousand words ,I would like also to see diagram of serise plumbing .
Also what is a uat and why used it.
Old 09-23-2022, 01:59 PM
  #42  
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Default

The original post was about 15 years ago, hopefully the problems sorted by now.

A 'UAT' is just a fancy header tank with a fabric sock made from 'mystery material' over the fixed central fuel pickup.
It'a an acronym for Ultimate Air Trap, just marketing BS.

https://shopbvmjets.com/index.php?ma...products_id=49

Just google BVM UAT

Just like a 'Hoover' is sort of a generic term for a vacuum cleaner in the UK UAT has become a generic term for a header tank. In use it is 100% full of fuel so, in theory, the fuel pump cannot suck air bubbles which will stop engine. It's not the only way to ensure steady fuel flow to the engine.

The drawing is the most basic fuel system using one tank & a header tank {UAT}, not shown are drain lines, fill lines, valves, filters, solenoids etc..

A series fuel system would have another fuet tank with a moving clunk feeding into the 'vent' line of the fuel tank in the drawing.
Series in this case means one after the other.

Attached Files
File Type: pdf
i6044.pdf (36.3 KB, 6 views, Original Link)

Last edited by Boomerang1; 09-23-2022 at 02:10 PM.

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