Tomo's new fuel tank - production

[Tomo]

So following on from a previous thread a while back about me making a new fuel tank for my plane... well it's slowly coming together, and I now have it in my plane and getting it all back together again. Can't wait to get it finished as I'm getting itchy feet!

 

Here are a few dodgy photos from my phone... I have it all mounted and plumbed up tonight but was to dark to take photos on my phone so you will have to wait till tomorrow for that. But in the mean time here are a few to start off with.

 

 

Cutting it out

 

 

The general shape...

 

 

Welding it together

 

 

Acid washing it

 

 

You can see the drop down on the bottom where the pick up will be sucking from, and also a fuel drain on the bottom of it.

 

 

It fits!! Trialling it on for size...

 

 

Getting the top together, with fuel gauge and pick up pipes, breather and filler inlets.

 

 

Attaching the pick up hose onto the pick up tube welded to the bottom on the inside of the tank.

 

More photos to come tomorrow...

 

 

[Kyle Communications]

The material looks a bit thick Tomo...how much does it weigh?

 

 

[Kyle Communications]

Did you do the tigging?

 

 

[RKW]

Nice welding job, Tomo. Tig or Mig?

 

 

[Tomo]

Mig, 4mm plate. My mate helped weld it, so I can't take all the credit!

 

Weighs about 4.5kgs, 50ltrs capacity

 

 

[Kyle Communications]

4mm !!!!!!! holy crap Tommo you dont fly a bulldozer do you

 

 

[Mick]

4mm !!!!!!! holy crap Tommo you dont fly a bulldozer do you

He does now!!!!!!!!

 

 

[djpacro]

http://www.aircraftspruce.com/catalog/mepages/5052H_alsheet.php

 

With the shape of Tomo's tank will need some design refinements to stiffen the flat sides and ends.

 

 

[fly_tornado]

4mm!!!

 

 

[Guest Maj Millard]

Fitted in the same position as the old one Tomo ?..........how much extra weight ?..................................Maj...

 

 

[Tomo]

4mm !!!!!!! holy crap Tommo you dont fly a bulldozer do you

Haha!! Just some stuff we had laying around, and it only added a couple kgs extra to the old tanks weight, so I'm not to concerned at all. Still plenty under MTOW even if I'm dripping wet!!

 

 

[rankamateur]

4mm !!!!!!! holy crap Tommo you dont fly a bulldozer do you

When you weighed the same as Tomo you could have been extravagant with the guage of your materials too Mark, sure you don't want to pull those dual tanks out for a while, buy you a bit more time to do the hard yards.

 

 

[cscotthendry]

Tomo:

 

It looks literally bullet-proof mate!

 

 

[turboplanner]

Don't listen to them Tomo, how many threads have we seen talking about tank leakage.

 

 

[XP503]

Looks great Tomo! I would never be able to build something like that, what does the acid wash do? Does it stop the material contaminating the fuel?

 

 

[turboplanner]

Puts holes in the tank for a start so he can complain about the leaks.

 

 

[Tomo]

Looks great Tomo! I would never be able to build something like that, what does the acid wash do? Does it stop the material contaminating the fuel?

Thanks David! I guess that's what I like to do... design and build things! The acid wash is just HFS04, basically a cleaner and brightener for Aluminium. Makes it nice and clean, and shiny!!

 

 

[ahlocks]

Hey Thompson.... that fuel tank of yours.....

 

If it doesn't work out, bang a combination lock on it and sell it as a safe!

 

 

[turboplanner]

This raised the interesting question of what is a safe material thickness for an aluminium fuel tank.

 

The big balls of flame you see in aircraft crashes only occur when the tank bursts.

 

There have been many examples of semi trailers rolling with 35,000 litres of petrol, maintaining integrity and only burning in columns from the vent stacks releasing boiling petrol.

 

However if the tank splits or bursts and dumps the lot, you are in for a big fire and without a firesuit, airways protection are cooked so to speak.

 

ADR17 addressed tank mounting breakaway, since the tank can become a missile if it comes loose, and structural integrity.

 

Most of us would be familiar with how easily a balloon full of water bursts.

 

The ADR corner test consists of:

 

1. Fill the tank with water to the equivalent mass level of fuel, then seal it

 

2. Position the tank so the impact point is vertically below the COG

 

3. Allow the tank to fall freely for not less than 9 metres (29.5 feet) on to a solid surface (9 mm plate on concrete)

 

4. Maximum leakage to be 30 grammes per minute

 

At 30 grammes per minute there can still be a fire, but a small one, hopefully away from the pilot

 

In the transport industry, all the tanks we'd been using for years failed the test and we had to get our act together fast.

 

 

[facthunter]

Don't worry about any reinforcing of the flat surfaces Tomo. 4 mm? Its "STRONG" enough mate. Nev

 

 

[pudestcon]

Did you install any internal baffles to stop fuel 'slosh' Tomo?

 

Pud

 

 

[Tomo]

Here's a shot of top of the tank, just tidying up the wires now and she'll be looovely!

 

 

Did you install any internal baffles to stop fuel 'slosh' Tomo?Pud

Negative! Thought long and hard about it, but in the end decided the tank wasn't big enough to warrant the extra weight.... .... or trouble of doing so.

 

Just got back from test flying it actually and it goes brilliantly. No issues with sloshing, balance etc... just need to get out and have some fun now I'ma thinking!

 

New prop, new tank... just a bit of paint tlc and she'll be brand spanking new!

 

 

 

[metalman]

Good to hear Tomo, I've built a fuel tank or two and I'd have to say if you ever decide to do the Canning stock route at ground level it should hold up nicely! ;-)

 

Baffles ( if you decide to do a light weight one) serve a couple of purposes, one is to stop the fast movement of fuel and the imbalances that go with 40 odd kilos doing their own thing , the other is in a lightly built tank you can use the baffles to strengthen the unit and stop the sides popping( oil canning) .

 

Turbo, having the tanks in the wings would be the best thing for aircraft( I've never like having fuel and people in an aircraft cockpit together) there just isn't the weight range available to build tanks the ADR standards , it would be nice but not practical , I wonder if the foam cell they use in race stuff would help contain the fuel in a prang ?

 

Met

 

 

[Bandit12]

I've used the anti slosh foam in two auxilliary tanks for long range motorcycles, and know a number of other people who have too. Wonder if there is a good reason not to use them in an aircraft tank?

 

 

[turboplanner]

Good to hear Tomo, I've built a fuel tank or two and I'd have to say if you ever decide to do the Canning stock route at ground level it should hold up nicely! ;-)Baffles ( if you decide to do a light weight one) serve a couple of purposes, one is to stop the fast movement of fuel and the imbalances that go with 40 odd kilos doing their own thing , the other is in a lightly built tank you can use the baffles to strengthen the unit and stop the sides popping( oil canning) .

Turbo, having the tanks in the wings would be the best thing for aircraft( I've never like having fuel and people in an aircraft cockpit together) there just isn't the weight range available to build tanks the ADR standards , it would be nice but not practical , I wonder if the foam cell they use in race stuff would help contain the fuel in a prang ?

 

Met

Since tanks are a safety item, you have to be able to demonstrate resistance to bursting by computations or buying from someone who has done computations, or by a recognised test such as ADR17.

 

We're building truck tanks now at 600 litres and that's a thin skin surrounding half a tonne of fuel which has to drop the 9 metres.

 

I've also built a lot of tanks and had a lot of failures with steel and aluminium - cracks radiating out from the mounting, Oil can/stress cracks radiating out from the baffle welds, general oil canning fractures, spigot fractures, brass ferrule fractures, and baffles cracks extending far enoug to snap the baffle off in the tank.

 

Over the years I've built heavier in the weak spots, and would be confident of a 9 metre drop test with a little aluminium tank.

 

We had a good thread on fuel tanks which included quite a debate on fuse vs wing tanks. If the tank doesn't burst it doesn't really matter where it is. Fuse tanks have the disadvantage in cog migration, wing tanks are more difficult to measure fuel with and you stand more chance of a walk home.

 

Foam cells retain the fuel like any sponge so it is released at a slower rate.

 

Thinking this through I realise this advantage goes hand in hand with a fire crew being on the scene within seconds and just makes their job that much more certain so while I might have encouraged it in past discussions, after thinking about it I'd suggest its a race track thing.

 

As much as I said I'll build the tank strong, weight is super critical in a race car, and I'd normally drill five of six holes through the flanges (opposite the tank weld) where they are just in compression, and also drill holes through the mounting bolts, trim the worm drives etc.