[Kahuna]

I got roped in again for a little detail on my wet wing smoke tank.
Issues:

1. In fuse tanks are trouble. Leaks, oil spills, plumbing

2. In fuse tanks take up valuable baggage room

Answer: Build a wet wing smoke tank.

I analyzed the wings and determined that on the 8, the most logical place was the left wing, wing root area. Biggest problem is the aileron push tube area. This means a forward baffle is required between each rib.

The heart of the challenge is 2 fold.

1. Seal it just like a fuel tank

2. Gaining access for the future leaks.
During the build process is pretty easy to seal everything. I used the wing walk plus 2 bays totaling ~13 gallons. Inboard and outboard ribs need caps on the lightening holes. Need to plumb a pickup and vent. You dont get any during build pictures cause I didnt take any. Too busy building. Here is a top view. You will notice rivets along a line above the filler cap. These are the baffles between the ribs. Made from bending .020 sheet into squares and fitting them in between each rib. Pop rivet in place with baffle flanges facing forward to as to be able to fay the proseal joint well from the inside.

This is the only build picture I have. On the right side of the picture is the left wing. You can see the caps on the rib and you can see the baffles between the bays. Farther away is the wing root. Your looking at the bottom of the right wing on the right side of this picture. Larger pic here.

Next, the key to success. ACCESS. When the tank leaks, and it will, you have to be able to get in there. The wing walk ribs are so close that you cant just stick your hand in from the wing root. So I built a giant access panel, secured with screws to the ribs and skin. With this off, I can get to every square inch of the inside. I did not do this on my first set of wings and of course it leaked and of course I could not get in there to fix. Note to self. MAKE ACCESS.

 

[MeAndMyToys]

Thanks

for taking the time to reply. I've been lurking here for a few months and the folks in here are soooo generous with there time and information. I will be starting to build soon and have learned so much. Thanks to ALL of you. Going to make my donation now.

 

[Snowflake]

With a removable panel, that looks like it would be possible to retrofit to an existing wing. More work, to be sure, but at least do-able. I like that you're using a place in the airframe that is otherwise unused... The elegance of that appeals to me.

 

[rocketbob]

As I recall last time we talked the pickup was towards the front, correct?

 

[rvmills]

Thanks Mike...much apprecitated!

Dog-gone it, the racing buds have me building an 8 tail for my 6, and now you have all these great reasons to build new wings.

If F1 Boss Mark had a set of EVO wings...or that new composite-spar jobber, I might be tempted. Might mess up the FFI sight picture though! Probably wouldn't hold enough smoke oil!

Geez, I should just build an 8...but I like my motor...then again, you have an answer for that too!

Thanks again!

Cheers,
Bob

 

[Kahuna]

With a removable panel, that looks like it would be possible to retrofit to an existing wing. More work, to be sure, but at least do-able. I like that you're using a place in the airframe that is otherwise unused... The elegance of that appeals to me.

Absolutely no way no chance you get that done on an existing wing.
Couple things come to mind.
1. The fwd bafles can only be put in place with either the top or bottom skin completely removed and preferrably both.
2. The rear spar reinforcement, doubler plates, and rivets must be set with proseal. A superficial covering of proseal will never get the job done right. It will leak.
3. Rib caps covering the lightening holes must be installed from the pressure side of the tank, meaning the inside. I supposed it MAY work if installed from the outside and just using the proseal join to hold tank pressure against the joint but I have not tried it and I wouldn't.


I have a fixed pickup, 90deg bulkhead fitting in the lower rt. rear of the tank. Running the tank dry leaves about a pint, little more, left in the tank. The space between the ribs, makes it difficult to really to anything more than fix a bulkhead fitting to the rib and be done.
Now. Having said no way no chance, anything can be done given enough time and money. Surely it could be done on an existing wing, but no way Id do it. There is so much to undo. It would put the plane outta service for quite some time. Thats a no starter for me.