Bearhawk Experimental Airplane Build : Fuel Tanks

Experimental airplane scratch build Bearhawk 4 place. Fabricating fuel tanks.
Build Log: bearhawk2020.b...
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[@scratchbuilder5952]

I learn something every time I watch

[@hu5116]

I would not have riveted them. I would have made a jig to hold the pieces and welded it all. The internal baffles you leave holes in the tank skin to weld to the baffle. Might have needed a couple alignment pins welded to the baffles that go through similar holes. Could have done the whole thing with no rivets and no leaks. Probably other ways to do it too. But thanks for an interesting build!

[@massiveheadwoundharry6833]

Great job! Thank you for taking the time to share your knowledge and talent.

[@Ryan22128]

Awesome job. Welding thin aluminum like that you are bound to get warping. I learned alot from this vid. Thanks

[@BSpotBuilds]

Thanks

[@WowRodg]

Wow, thanks a lot. Very informative. Love your channel 🤟

[@johnelliott4521]

Missed cut corners very professiona work

[@johnelliott4521]

Beats dealing with sealant, adds very little weight

[@manoo422]

That would appear to be the worst possible way to make an Aluminium fuel tank...What will those joints be like after a year of vibration?!!

[@BSpotBuilds]

There are a lot of tanks made this way flying without issue, so I would conclude that you arm chair engineering determining there will be issues is proven wrong by the data. I looked for your fuel tank video showing the proper way to design a tank and could not find it.

[@PeterPasieka]

If you welded the tanks why did you need all those rivets? Would it be enough to have just enough to hold the shape prior to welding?

[@BSpotBuilds]

An experienced welder could weld it without riveting first. For me by fabricating and riveting first then welding it separates the two process making it easier two keep all the parts in the correct positions during welding.

[@JPfromCA]

Great job on this build!

[@BSpotBuilds]

🛩

[@johnelliott4521]

I did not see ports in baffles.

[@paulkainer269]

I didnt see ports either in baffles. I am quite "Baffled " that he didnt show that part. Lol but i am sure he did

[@BSpotBuilds]

The baffles have the corners cut off to allow fuel and air flow. Watch from 6:48 and 14:45.

[@BSpotBuilds]

The baffles have the corners cut off to allow fuel and air flow. Watch from 6:48 and 14:45.

[@bernardmauge8613]

I have welded alum tanks before and while I admire your skills and attention to details, I dont think you did it correctly. The most disturbing part is the flange bending @90 degrees. Aluminum should never be bent in the non annealed state. It is too hard and will result in stress cracks resulting in fuel sweating on the walls of the tank I would even avoid bending the long sides. This is not a tool box drawer. All that flange business is a huge waste of time. You can butt weld all the sections, tack them and weld them. Regarding the baffles they can be fillet welded top and bottom first, no need for flanges. Lastly your holes for fuel circulations at the bottom are too small to allow the fuel to travel freely in a sharp turn when the tank is low. You need circular holes at the bottom of the baffle to avoid sucking air on a sharp banking motion. You want as much fuel as possible near the suction tube. I admire your craftmanship, but I can assure you we dont weld alum tanks like that. You also need to remove the oxide before welding with a chemical etching solution. I can hear you IF struggling to break the oxide layer. Way too loud. Alumine oxide is the reason you are getting the pin holes. Add a 1 percent helium in your argon, it will weld a lot better. Stay safe and busy. Regards from France.

[@BSpotBuilds]

Thanks for you feed back. I didn't design this tank it is a tried and true design with many preforming successfully in the field. 5052 with generous bend radius does not need annealing to prevent cracking. The baffle cutouts have a total area of ~1/2 inch, a half full tank it is capable of flowing over 7 gallons per minute through this size hole. While I am sure your techniques are sound I am not sure they are the easiest way for the average home hobbyist to produce a usable product.

[@sawyersdad5292]

@@BSpotBuilds Yeah I was watching Sonex and they do there bending the same way... I don't know anything about welding but it looks good.

[@whitetrashgarage8110]

You may want to talk to Van's and many other manufacturers about their tanks...