Inflight Refuelling

[Dobbs]

For me the safest option is a positive pressure system, gravity or pump. While Ystervarks option is probably the simplest and most cost effective, it relies on a totally airtight connection between the main tank and the spare. At 13 L / hr fuel consupption, the displacement is only around 217 ml / min, so it would not take much of a leak to break the syphon effect. I know for a fact that the cap on my windlass, and it was a new tank when I got it, is not air tight.

Secondly, the first you would know that you have lost suction is when the noise behind you goes quiet prematurely

[Sukkelaar]

Hi Blue Max

You can premix before you load the container on the backseat then you don't have to carry extra two stroke oil.

And if you are using a Autolube system it should be good for your complete tank plus another 50litres.

Regards

ps Will visit you soon

[Blue Max]

Omtrent elke naweek hier.
Jy,s welkom.

[ZULU1]

OK, been watching this with interest from a iPhone, I have sourced a forestry chemical tank that I will use for trials, a 12 gram paintball gun cartridge used in a hand operated bicycle pump, a asco valve and our caps. The asco valve will be actuated by 4 x 1/2 AA Li ion batteries connected to our yrless remote. So in flight refuelling will be press the bar remote and watch tank fill. This is prototype and on bench use before we take to skies...

Initial problems may be the expanding CO2 which will creating water so I may use a air con filter drier in series. (Bernoullis equation).

Answer to tank, the roto mould process is perfect for low volume production and what makes it perfect is the mounting of inserts to attach devices with screws. It may be as thick as we require. I have considered two interlinking tanks for ease of use carrying and hence the pressure fill method.

This design as its stand alone will be suitable for 4 x 4 s etc.

I received a PM for a helpful chap and I have ordered the pump in question from our local Autozone spares. Thanks.

Zulu1

[Tumbleweed]

What about considering a 20 lt pesticide back mounted sprayer?

Besides being solvent compatible, it appears to have all the plumbing required. Just add a small stopper, similar to the IV drips, which you can open in-flight?

Cant seem to load a pic, but they wholesale for around R250.00

Sprayer.jpg (40.03 KiB) Viewed 2490 times

[John Boucher]

What's happened to this project Paul?

@Grumps... I have one of these you suggested...

Look at this petrol can. someone take orders and import a few
http://www.flo-n-go.com/products/product_duramax/

[Vatso]

There is such an easy solution to this

use a boat jerry can run the fuel pipe to the front pack with a Fuel Siphon Pump they use to get fuel to the motor - the pilot can pump the fuel by hand until it runs into the main tank and gravity will take over that simple!

[John Boucher]

Not going to work for all types of aircraft.... maybe for trikes

[Vatso]

Okay sorry good point - the only other way would then be a pump if one needs fuel to go uphill

[Blue Max]

I tried both options on my trike.
The electric fuel pump is an overkill. You switch the pump on for one fraction of a second and the fuel start flowing on gravity and the pump can be witched of again..To go to the trouble of an elctric fuel pump that is only needed for a fraction of a second does not make sence to me.
The other method ' blow in the pipe' is the one that I use and it works perfect for me..
Witch ever method you use you will find that you will need a stopvalve (tap to close) the flow of the fuel feeding into your tank.
That is important because.:
1. when it gets hot the fuel in the tank on the pax seat start to feed outomaticly because of the pressure (heat)that buids up in the container.
That causes the system to start feeding at a stage when there is not enough space in the tank below to store the fuel..That happened to me.!!!
2. Any hard bump or pressure against the plastic container can also cause the fuel to start flowing.

Thus, you need to install a valve to stop the flow of fuel whenever required.

[Vatso]

This is an easy fix

12 Volt Fuel Solenoid Valve
http://www.autoelectricsupplies.co.uk/p ... tegory/121

[Tumbleweed]

The reason why I proposed the 'pesticide sprayer' application is because it has a plunger to initiate the pressure and a trigger/ forcet mechanism. Just remove the nozzle and fix to the fuel tank lid.

[mulderpm]

Very interesting topic. Depending on the design of the system in flight refuelling definitely makes for safer flying. And a simple system makes for a safer system. So, gravity feed is the way to go for me. Ystervarks sytem relies on an air tight connection between the main and reserve tanks and if it fails/blocks/restricts the flow the main tank will build up a vacuum.

Although I have not tried the following idea, I have seen it working. It relies simply on a gravity feed between the two tanks. Take Ystervarks picture, but instead of connecting the first pipe (labelled, “to tank breather”) to the breather of the main tank, connect it to a new separate hole in the cap (for this purpose only). The second pipe (labelled ,“breather”) coming out of the reserve tank, on the back seat, is routed to beside the pilot with a plug in its end. When more than the reserve tanks fuel (25 liters) has been used the pilot removes the plug and blows into the second pipe, thus starting the siphoning process. The purpose of the plug is to prevent the airflow from prematurely starting the siphoning process. The new separate hole in the main tank cap can be plugged when not in use. Simple and safe.

I see oom Paul has highlighted the possibility of unwanted/premature siphoning. His tap will prevent this. But if you fit a tap, then you should not need the second pipe for starting the siphoning. Just prime the first pipe and close the tap. When you open it again siphoning should continue?

[Renegade2]

Hi Zulu1
I would definitely be interested in this system. My requirements for a fixed wing are a bit different to trikes. I reckon that 90% of the time I would use it for normal refueling, but it would be nice to be able to carry extra fuel in the aircraft on occasion. I notice that some people want 50 or 60l and others want 25l. Carrying a full 50l container is damn hard work. I suggest that you make the tanks modular so that two 25l tanks could be carried individually and locked together on the aircraft seat if required. That gives more options as far as capacity is concerned. Having lots of attachment points and carrying handles is important so that you can strap the tanks in and tie bags etc to the tanks.
I need to get the fuel about 2.5m up from ground level to get it into the wing tanks. I need a remote switch that I can control at the wing tank nozzle if using a pump, or a shut off valve for a pressurised system. A lot of fixed wing aircraft use either a tiny inaccessible vent tube – normally exiting from somewhere on the bottom of the aircraft (cheetah etc) or a vented cap similar to what you would find on a car or motorbike. Also the tank is often higher than the seat - either mounted above the pilot’s legs in the fuselage or in the wing. The siphon system would definitely not work. For most fixed wings, it would be easier to tie the system into the delivery line from the tank to the engine with a tee and a non-return valve than to try to adapt the fuel caps if you want to re-fuel in the air. Personally, I would rather land and re-fuel than mess around with the fuel system and introduce another point of failure. I would like to have the re-fueling process as painless as possible though. I don’t want to have to get a 25l can up to the top of the wing without a ladder. Another requirement is that the system must be absolutely leak proof. You don’t want fuel sloshing around inside the cockpit or even fumes. I use the Addis fuel containers and they are not leak proof. If they fall over in the boot, it takes weeks to get the petrol smell out of my car.

[mulderpm]

Hi Paul, can you make me one of these? I will refuel even if I don't have to Not in-flight though.