Plastic Tanks

[Mark Kunz]

My new plastic tanks arrived from Rocky Mt. Wings yesterday.

[Av8r3400 1179]

My new plastic tanks arrived from Rocky Mt. Wings yesterday.

Mark, you must have the same issue as me, you need to log in on every visit...

[dholly 718]

Hmm, so Stace is also providing poly wing tanks? I wonder if they are the same as or sourced from Airdale? I'd love to see a few pics, particularly the fitting and fill areas which I've noticed did vary from Airdale depending on their design evolution.

Edited 28 Oct 2009 by dholly

[Russ. 7]

I have the Airdale tanks in N844RS. They are very slow to fill, and hold about 10.5 gals. The pictures at Wingtanks.com are of my installation. I would also like to see pics of your tanks. Russ

[Trackwelder 12]

My new plastic tanks arrived from Rocky Mt. Wings yesterday.

How well do they fit the Avid STOHL wing and what was the price? Pictures?

[Bandit 286]

$150 per tank. A whole bunch cheaper than anybody else. They are Stace's own molded tanks. I'll try to get pictures of them.

[dholly 718]

$150 per tank. A whole bunch cheaper than anybody else. They are Stace's own molded tanks. I'll try to get pictures of them.

^ now that is some very interesting news. I'm sure the Ridge Runner, at least the early models, have a nearly identical rib profile as the Avid HH. The Kitfox Models I-III are within a short and curly on the under camber side. I would love to see a HH rib held up against a RR rib or Stace's tank profile if'n you have any handy.

P.S. pics are the same I posted at the Ysite showing Avid HH vs. KF I-III comparison

[Trackwelder 12]

My new plastic tanks arrived from Rocky Mt. Wings yesterday.

I have emailed Rocky Mt.Wings about their tanks, at that price I am Interested. Are they fiberglass or plastic? Resistant to alcohol? What is the width? I have seen that Just Aircraft uses the same spar sizes that Avid used and that they use an extrusion to strengthen their spar a few more parts and I will be making my own Avid inspired plane. After I get my A model in the air.

[Bandit 286]

Stace's tanks are plastic. Not sure of the exact width but, my ribs are 17 3/4" center to center. It looks like the tanks will fit between them ok. They have two cone shaped nipples on bottom back of the tank. Here I will drill and tap each one. Then install a quick drain on one and the fuel outlet on the other. Between the tanks will be a bulk head fitting so each tank can drain into the other. Also each tank has its own filler neck. I will try to get pictures this weekend.

[Trackwelder 12]

Bandit, I see that we are almost neighbors as far as the internet goes, how far along are you on your plane or are you just making improvements?

[Mark kunz]

Bandit, I see that we are almost neighbors as far as the internet goes, how far along are you on your plane or are you just making improvements?

[Mark kunz]

Fixing old tank

[dholly 718]

Got pics?

[Mark kunz]

Got pics?

[Mark kunz]

I'll try to post pictures tonight.

[Mark Kunz]

I'll try to post pictures tonight.

Don't know how to post pictures any more.

[akflyer 1427]

Don't know how to post pictures any more.

I dont think you are signing in. If you don't log on to the site, it wont show the icon to post attachments. If you are having trouble logging on, let me know and I will reset your password and see if we can get you back on track!

[Bandit 286]

I dont think you are signing in. If you don't log on to the site, it wont show the icon to post attachments. If you are having trouble logging on, let me know and I will reset your password and see if we can get you back on track!

Weighed my tanks, 6.2lbs each. Put gas in them, they hold 5.2 gallons each.

[akflyer 1427]

Hell yeah! looks like your getting close to getting her back in the air! From the looks of it, the new tanks fit pretty well! If there are any bastad parts to the install, post it up so other needing the tanks can save a step of two!

[dholly 718]

Thanks for the pics, looks like wingtanks.com has some competition. After seeing these tanks, a couple of thoughts/questions come to mind:

1. is the front to rear spar spacing in the Ridge Runner (RR) same as Avid's (27-1/2" if I recall correct)?
2. are these tanks installed in the RR without any top skin (ie. no top ply or aluminum skin as used in the wingtanks.com poly tank install)?
3. are these tanks installed in the RR using same procedure as Kitfox, ie. glue to spars w/ Dow Corning 739 RTV Plastic Adhesive?
4. when installed in the RR, is there any supporting under-structure (like the wingtanks.com support tubes), or do they simply sit on the spar coves?
5. the filler neck and nose rib indentations look to be spaced perfectly for Avid wings with 18" o.c. rib spacing and (2) nose ribs between
6. not good with Hauler 12" o.c. ribs and (2) or (3) nose ribs between, ie. nose rib spacing over tank will not match rest of wing
7. for HH wing, even if covered with top skin and 'false' short rib tails are used behind tank to keep symmetrical rib spacing look, filler neck falls right on rib line
8. no groove along tank top for longitudinal nose rib stringer used by Avid
9. tank sumps require exposed (below wing, rather than in-wing and through root) fuel line routing
10. no 'neckless' filler option for 2nd tank in series?
11. same (leak-prone?) press plumbing connections for tanks in series

Just thinking out loud, what else am I missing?

[Bandit 286]

Not sure of the exact measurment, but the tanks do fit between front and rear spar inside of the old tanks.

I think the RR covers with fabric.

Stace said silicone them in, then use houshold spray foam. I am going to just spray foam the 4 corners.

Look at the bottom of the tank. You glue three supports from rib to rib then set the tank on these. I am going to set mine on the bottom of the old tank.

No stringer at the top of tank. None on the fiberglass one either.

Tanks won't fit 12" oc ribs.

Tank sump and fuel outlet are on the bottom outside of the wing with a fiberglass tank.

All tanks have filler necks.

Brass threaded bulkhead fittings from tank to tank.

[dholly 718]

Ok, this might be a little hard on the eyes but here goes...

- Not sure of the exact measurment, but the tanks do fit between front and rear spar inside of the old tanks.

Does the entire RR poly tank, including the cove ears, fit inside your Avid oem f/g tank BETWEEN the spars? Or does the tank sit between while the top ears of the tank cove sit ON the spars? If they set on, is it a snug fit between spars?

- I think the RR covers with fabric.

That was my guess too, looked like nose ribs could be glued into the indentations which would make it easy to run fabric all the way to the root. I prefer the look of nose ribs along the entire wing rather than transitioning to a flat-top inner surface over the tank as in the oem f/g tanks or the wingtanks.com poly tanks with a top ply or alum skin. What are you going to do on yours?

- Stace said silicone them in, then use houshold spray foam. I am going to just spray foam the 4 corners.

Would solid foam all around except for fitting access provide a much stronger wing? Sure would be a beyeotch to get out if you ever had to, but doesn't seem like a big weight penalty to do it. Are you going to use a hard ply cover over the tank or what's your plan there?

- Look at the bottom of the tank. You glue three supports from rib to rib then set the tank on these. I am going to set mine on the bottom of the old tank.

Ok, that's kinda the opposite of the wingtanks.com poly install. I'm not sold on drilling into the spars for support brackets, but that does seem stronger than attaching braces either to the underside of the capstrips or even the rib web itself. I wonder if RR uses a sheet of ply plus the support tubes for a new wing install, like wingtanks.com recommends?

-No stringer at the top of tank. None on the fiberglass one either.

That stringer channel is something I noticed on one of the wingtanks.com versions (three different versions to date I believe). Don't know if the current version includes that but I like it because it allows the use of nose ribs all the way to the root, should one decide to dispense with a hard top skin over the tanks and under the fabric. More work for sure but nicer aesthetically, IMHO, though I don't know if the top skin is a strucural requirement, a good idea or simply not necessary when removing the diagonal drag tubes in the wing to fit these poly tanks. If RR doesnt use one...

- Tanks won't fit 12" oc ribs.

Obviously not between two side-by-side 12" o.c. ribs. And if you retrofit the poly tanks into a HH wings with 12" o.c. spacing and old oem f/g wing tanks, doesn't matter because the center tank baffle is the same. However, on a new wing build w/ 12" o.c. spacing, one can use new long ribs for #1 root and #4 rib

@ 12" o.c.

, but omit and replace #2 and #3 ribs with a new single rib @ 18" o.c. from root, between two new poly tanks. The best news is, that layout replaces the first three flaperon hinge rib tails

used with the oem f/g tank

with full long ribs at the hinge positions. So, much stronger hinges IMO.

- Tank sump and fuel outlet are on the bottom outside of the wing with a fiberglass tank.

Yes but when comparing the two poly tank options, I think I prefer the other tank because the fittings allow for in-wing routing of fuel lines. I don't care so much for a quick drain on each wing, so long as I have a header tank with one.

- All tanks have filler necks.

Wingtanks.com offers a neckless tank with sealed filler if you want when using two in series. I do like the idea of two filler necks for fast fills on tanks plumbed in series but prefer looks of a single cap, not to mention that little voice in the back of my head saying something about potential leaks at the inboard cap seal. Either way, I see the RR poly tank filler neck is centered while the wingtanks.com one is offset to the side. That might come into play for me in a new wing w/ 12" o.c. ribs ie., offset keeps the filler from falling right on a rib line... I think that might look goofy.

- Brass threaded bulkhead fittings from tank to tank.

Threaded, huh? I like that better than push fittings but can you even get inside the tank to hold a nut?

Anyhow, thanks and three beers or cheers for taking time to answer all these questions. I'm sure a lot of folks are interested in these tanks and, at least for now, you be the only Avid guy we know that gots 'em.

[Bandit 286]

Not sure of the exact measurment, but the tanks do fit between front and rear spar inside of the old tanks.

I think the RR covers with fabric.

Stace said silicone them in, then use houshold spray foam. I am going to just spray foam the 4 corners.

Look at the bottom of the tank. You glue three supports from rib to rib then set the tank on these. I am going to set mine on the bottom of the old tank.

No stringer at the top of tank. None on the fiberglass one either.

Tanks won't fit 12" oc ribs.

Tank sump and fuel outlet are on the bottom outside of the wing with a fiberglass tank.

All tanks have filler necks.

Brass threaded bulkhead fittings from tank to tank.

The front and back of the cove just touch the spars while the bottom of the tank sits on the old f/g tank.

Just going to foam the corners. I plan on sheeting both rib bays with al. from leading edge to trailing edge, if the nutserts work like I hope they do.

I think RR uses only the support tubes, no ply box.

I was told that if you are starting with a new wing with no tanks you need the ply box if you do not use diagonals in the Avid.

I might not add the quick drains either. Have one in the header tank too. I would like to use my fuel outlet fitting though, it has a finger strainer on it. I might also use a bulkhead fitting coming out the inboard side of the inboard tank then down to the header tank like RR does it.

To install the bulkhead fitting you drill a 3/8 hole in the center of a penny, and on the side of your tank. Put fuel lube on the penny and the fitting, fish a length of wire through the bulkhead fitting hole up to the filler neck. Slide the penny on the wire then the fitting,pull the penny and fitting through the tank and work it into the hole, a little more fuel lube, then another penny and the nut, then tighten.

[Bandit 286]

Finished spraying siver tonight. Finish color tomorrow. Should have it back together by sunday if everything goes good.

[akflyer 1427]

Finished spraying siver tonight. Finish color tomorrow. Should have it back together by sunday if everything goes good.

Will be nice for you to get it back in the air and not have to worry about that leaky tank anymore! Did you destroy the old tank or hang on to it? May be easy to fix with it out of the wing. If you still have the old tank and have no plans for it, I know a few who may be interested in it for a science project.