Electronic fuel 3-way valves

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MolsonB

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Hi, I'm looking to simplify my fueling system during my design phase. I'll have an auto engine with 4 fuel tanks in wings (supply and return lines for each tank).
Trying to fit 8 hoses (4 tanks x supply and return) to a manual fuel selector isn't out there. The closest thing would be Groco FV65038 6 Port Fuel Valve and I would need a few of them.

I'm looking at electronic controlled 3/6-way valves to do the work. The best aftermarket I've seen so far are for biodisel applications, like the Greasecar SV98 6 port Greasecar SV98 6 Port | Greasecar Vegetable Fuel Systems Small and compact and allows to install AN fittings on the stainless steal body. Viton (fluorocarbon) o-rings are good for fuel with ethanol (car gas).

6port_w_fittings_0.jpg 6Port_nofittings2.jpg


The best OEM I've come across is Pollak 42-149. It came out of trucks to switch between dual fuel tanks. It's 75% cheaper and a lot smaller with latching switches that only draws current for a fraction of a second to transfer. The only downside is, it's plastic and only connects to fuel hose (with worm screw clamps). It also might connect to nylon hose.
6-PORT-VALVE_sb2.jpg




-Matt
 

BJC

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Hi, I'm looking to simplify my fueling system during my design phase. I'll have an auto engine with 4 fuel tanks in wings (supply and return lines for each tank).
Trying to fit 8 hoses (4 tanks x supply and return) to a manual fuel selector isn't out there. The closest thing would be Groco FV65038 6 Port Fuel Valve and I would need a few of them.

I'm looking at electronic controlled 3/6-way valves to do the work.
Sounds overly complex to me. What kind of airplane is it? Engine?

I am not familiar with the valves you mentioned, but I tend to be leery of anything other than manually operated valves for the main fuel tank(s). YMMV


BJC
 
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Midniteoyl

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Why have 4 feed and return lines? Why not connect the outboard tanks to the inboard tanks and pull fuel from them while returning to the outboard? 2 feed, 2 return, two fuel caps (outboard)..2 vents (outboard) - or one central vent cross-tied to both..
 

Matt G.

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How will you ensure that an electrical failure does not cause an engine failure due to fuel starvation because you could no longer switch tanks?
 

MolsonB

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Plane is a Revolution Aviation Tango. Tanks are forward / aft of the spar on either wing. I wanted the keep the tanks separate from each other to control the CG and weight. If I tied the front and rear tanks together per wing, I'd still have 2 outlets and a common return would fill up the undesired tank and shift the weight around. This gives me more control. Maybe I only want to fill up the fronts and leave the rears empty for a quick trip, as I fly I don't want the rear tanks to be filling up because of the return lines being shared. The plane will have a over 100G+ of fuel, so lots of weight to play with.

If there is a complete electrical failure, my fuel pumps wouldn't be pumping fuel so mute point. If it's just a valve failure, they default (N/O, no power) to the forward right tank, which is my last tank I'll draw from.

I'm leaning towards the Greasecar as I can attach AN-6 lines. Waiting on dimensions from the supplier.
 

Midniteoyl

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Plane is a Revolution Aviation Tango. Tanks are forward / aft of the spar on either wing. I wanted the keep the tanks separate from each other to control the CG and weight. If I tied the front and rear tanks together per wing, I'd still have 2 outlets and a common return would fill up the undesired tank and shift the weight around. This gives me more control. Maybe I only want to fill up the fronts and leave the rears empty for a quick trip, as I fly I don't want the rear tanks to be filling up because of the return lines being shared. The plane will have a over 100G+ of fuel, so lots of weight to play with.

If there is a complete electrical failure, my fuel pumps wouldn't be pumping fuel so mute point. If it's just a valve failure, they default (N/O, no power) to the forward right tank, which is my last tank I'll draw from.

I'm leaning towards the Greasecar as I can attach AN-6 lines. Waiting on dimensions from the supplier.
You have the XR version? I remember watching the Tango during development of the 2 place Tango and thought the tanks were ahead of the spar..
 

MolsonB

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Yes, XR version. And the engine is Rotary Rx8.

By treating each tank separate during construction, I have the ability run any configuration if I choose to join them in the end.

This picture was during construction. The return lines were made out of SS tube, that ran past the rib by the last access panel cover (before the sandpaper sitting on the spar). The chase tube is also missing in the aft tank.
IMG_20150512_181239.jpg

Complete before close-out.
IMG_20150527_133108.jpg
 

D Hillberg

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to slave everything to a single electrical system is not too smart, You're designing a smoking hole. (seen the results too often of an electrical failure causing a forced landing when a simple mechanical pump/control could limp home)
 

don january

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I have to ask, what is your plan on keeping track of what tank your on? pressure gadge on each line? or is it controlled electronically with LED lights? Good luck and keep us posted. Don
 

Toobuilder

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Any chance you can integrate a small header tank to ease the complication for all the return lines?
 

TFF

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Too complicated. An electronic fuel valve designed for an airplane would fail open to be safe. Why not link the tanks and just have two fill ports per wing; one for full and one for whatever your tab level would be.
 

Toobuilder

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The low wing hurts - a high wing gravity feeding a header tank would be much easier.

That said, I know of a guy who runs his Rocket with no fuel valves at all. Tank selection (toggle switch) turns on a small transfer pump at the wing root (pushing- important) fuel to the boost pump. He is completely dependant on electrical power. But is this a bad thing if the electrical system is reliable?

As pilots, most of us are highly apprehensive to any change from the status quo - and most of the time that is with good reason. Many of the revolutionary new ideas feature a demonstratably lower reliability or other performance deficit with just a little digging. Simple is reliable - yes, but one really needs to do an analysis to establish the probability and severety of failure of a new system compared to the status quo.

Mechanical valves can and do fail. And lets not forget how unreliable the human is in fuel management - how often do pilots run out of gas WITH ADEQUATE FUEL ON BOARD AND AVAILABLE? Too often.
 

Dan Thomas

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Mechanical valves can and do fail. And lets not forget how unreliable the human is in fuel management - how often do pilots run out of gas WITH ADEQUATE FUEL ON BOARD AND AVAILABLE? Too often.
What valve was in that Cirrus that went down in the Pacific enroute to Hawaii because the fuel valve failed? Wasn't that an electric valve?
 

BJC

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If you have to make a forced landing because the engine ran out of fuel, it is better if the airframe also is out of fuel.


BJC
 

MolsonB

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This 'status quo' always baffles me. People think we should still be flying the Wright Brothers design. Or why still using Lycoming made from 1960's.

A small micro-controller via android tablet will switch tanks by monitoring the fuel levels and/or me selecting them manually. BUT I'll have backup rocker switches that will override the computer and switch tanks. Again, if a valve fails or no power, they default to a tank, there is no 'off' option for them. It's either path 1 or path 2. Header tank will actually make things more complicated when taking about high pressure fuel systems.

I looked into Cirrus, but haven't found any electric valves they use in their systems.

This is quite a simple design. Each tank has it's own pre-filter in the wing root. Use dual fuel pumps for take off & landing.

fuel.jpg
 

SVSUSteve

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to slave everything to a single electrical system is not too smart, You're designing a smoking hole. (seen the results too often of an electrical failure causing a forced landing when a simple mechanical pump/control could limp home)
^ This. Especially with fuel tanks ahead of a spar. LOL

MolsonIce said:
I looked into Cirrus, but haven't found any electric valves they use in their systems.
The case in question involved a fuel starvation induced mid-Pacific ditching of an aircraft fitted with ferry tanks that may have had an electrical valve.

This 'status quo' always baffles me. People think we should still be flying the Wright Brothers design. Or why still using Lycoming made from 1960's.
The same can be said for the willful ignorance and hubris that thinks that "new" or "electronic" automatically makes something better. It may but it also carries new failure modes that have to be designed out or otherwise managed. Electronics is not my particular focus but I see nothing here that accounts for that.

Plugging in several pounds of wiring, electronics, extra tubing and switches to handle those failure modes and accomplish a task that can simply and elegantly be handled by a 2 lb valve that was derived from technology that was already an antique at the time of Queen Victoria just because you want to thumb your nose at "status quo" is- and pardon my bluntness- pretty **** stupid.

The main reason why we still use Lycomings and Continentals designed in the 1950s is because- unless you're abusing them or neglect them- the common models are as close to bulletproof as one gets in a close tolerance piece of machinery subjected to a wide variety of pressures, temperatures and accelerations. They aren't perfect but if you can't get reliability you need out of a Lyco-saurus then you probably aren't going to get it out of a modified car engine (remember that thing about additional failure modes? Yeah....the modifications to car engines to allow them to run a prop are just chock full of them). The smart money is on finding a good CFI to review how to handle an engine that is equipped with good engine monitor, with proper cooling baffling, etc.

If you need more reliability than that....I can give you the phone number of a friend who works in the sales division of Rolls Royce. Let's hope you have deep pockets.
 

mcrae0104

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(remember that thing about additional failure modes? Yeah....the modifications to car engines to allow them to run a prop are just chock full of them).
That statement is too broad. Certainly some auto conversions have complicated systems and PSRUs of questionable reliability, but the best auto conversions actually remove many modes of failure, making them more like the stone-simple Lycomings and Continentals.
 

Toobuilder

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One thing to consider since you are planning a "suction feed" system is the possible failure mode of one valve failing open to a dry tank - even if you have other valve(s) open to fuel, the suction will be lost for the entire system and no fuel will make it to the pumps. Of lesser consideration is the possibility of vapor lock when pulling a vaccum through all that plumbing - especially if you intend to use auto fuel.
 
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