Tip: Proseal ...The fact and the fiction

[WSBuilder]

Hey, how come nobody told me this was a messy process?!
Well, I installed the first four stiffeners last night and learned a ton. I want to say thanks to you guys for the collective suggestions (double gloves, ziplock on the scale, etc.) on tank sealing. I felt like I knew what I was doing right from the get-go because of this forum. I know I've got more to learn this weekend as I move to the ribs but I'm having a blast! I was a little dissappointed to find the new "quart" can of pro-seal only 5/8 full. And for those in the market for a digital postal scale, Staples just put their $35 unit on sale for half price. Since I know you've never seen the process I'll post pix later!

[longranger]

Originally Posted by WSBuilder

... and 2) would it be a good idea to thin the pro-seal a little for wet installing the rivets?

Sam Buchanan thinned sealer with MEK and got good results. I tried it a couple of days ago and couldn't get it to mix thoroughly. I may have added the MEK too long after initial mixing. I'm just going to stick (no pun intended!) with straight sealer.

[Don Patrick]

Rick, great information on the sealing of the tanks. Much appreciated. I don't know if this is overkill, but I really don't want to do all this work and have a leaky tank. So, I completely encased the shop heads and the flange with proseal...too much?

Any comments would be appreciated.

Here's a link to my pics:

http://mykitlog.com/display_project.php?project_id=820

Thanks

Don

[Seansull]

Thats what I did. Two tanks and no leaks

[Rick6a]

Originally Posted by Don Patrick

......Any comments would be appreciated.....

Looks okay to me Don. Since you are inviting comments, I will remark on something you wrote:

"Later tonight, I'll go in and proseal and 100% cleco another rib, and then rivet the rib I prosealed...."

My question (if I interpret your comment correctly) is why invest in the extra time and effort to install the internal ribs singly or one at a time? Unless you feel you would have difficulty accessing all the rivet holes, on the next tank why not install all 5 of the internal ribs in one session? Doing so will provide you with the following benefits: By clecoing all 5 of the internal ribs in place in one session, starting with the nose of the ribs and then "wrapping" the fuel tank skin around them as shown in my series of photographs (selectively abbreviated below) you will greatly reduce the chance of generating voids in the faying surfaces as opposed to "sliding" each wet rib into place one at a time. Also, installing all 5 ribs at once will minimize the number of times you have to mix up a batch of proseal.



In any event, it is always gratifying to hear from other builders who have learned that by working smarter rather than harder, the horror stories about "black death" we sometimes hear are completely overblown. You are learning for yourself that working with proseal is not that big a deal if the task is approached efficiently. Good luck to you Don, by the looks of your encapsulation method and supposing your fay seal surfaces are without void, I am virtually certain you are building at least BLISTER free fuel tanks.

One last thing...be extra mindful when you get around to installing that rear baffle. That seems to be the one area of fuel tank assembly many builders report leaks to emanate from, particularly the corners.

[Hornet2008]

Very timely post, and thank you for it, nothing beats experience, except a cold beer. I'm starting my 9 tanks once the proseal arrives from Vans.

[Don Patrick]

Hey Rick,

I started the prosealing 2 ribs at a time, then saw your wrapping technique afterward. I'm doing my left tank exactly as you suggested by wrapping it to avoid any voids at all.

It will be much easier doing one big batch, verses small batchces that I've been doing.

Again, MUCH thanks!


Cheers,

Don

[Rick6a]

Originally Posted by Don Patrick

....It will be much easier doing one big batch, verses small batchces that I've been doing....

Don,

It will become apparent to you that key steps in the wet assembly process will become much easier to accomplish and sometimes even fun. When you get to the point all the internal ribs are 100% clecoed into place....relax. It is important to understand that (within reason, of course) there are no pressure or time constraints. Reaching this stage of assembly, you enjoy the satisfaction of knowing you can set all the rivets at your leisure. For now, concentrate on fashioning an acceptable fillet seal around each rib making certain no voids, interruptions or other defects exist. If you simply must shoot rivets and can set them in a few hours, that's wonderful. Consider yourself Superman. If you can set all those rivets in a freshly sealed and very wet assembly in those same few hours and do all that without making a sloppy mess, you are indeed a Superman. Most of us are not that fast or talented. For most of us, it would take all day or several days to finally get all the rivets properly set, and that's a perfectly fine plan of action. For instance, in my experience with the freshly prosealed/100% clecoed fuel tank shown below, I did not start the riveting process until the next day. Actually, what the photo does not show is that I assembled both fuel tanks at the same time. Then, it took approximately 2-3 days spread out over several sometimes brief work sessions to complete the riveting on both tanks. Because there are no time constraints, I took my time. As often as not, I walked away from it when I got frustrated or tired. I did not hesitate to remove and replace even the slightest marginal rivet throughout the process. When the proseal is tack dry (which is the state of cure I prefer to work it), you will likely find that aluminum chips and rivet chunks produced by drilling out unacceptable fasteners is not much of a problem.

Enjoy the process for what it is Don. Long after your RV is painted and flying, I'm sure you will be continually pleased with the lasting high quality performance of your fuel tanks as a result of your efforts.

[SMO]

Rick, just curious as to why you wouldn't do the end ribs at the same time.

I am in the process of building new tanks for my -4 (only 3 internal ribs) and anticipated doing the internal ribs and the end ribs all at the same time, leaving them clecoed while the sealant set up.

Also, on the internal ribs is there a good reason to seal up the nose past the last rivet?

Thanks for sharing you knowledge!

[Rick6a]

Originally Posted by SMO

.....curious as to why you wouldn't do the end ribs at the same time.....Also, on the internal ribs is there a good reason to seal up the nose past the last rivet?.....

Mark,

My general suggestions are influenced to some degree by the physical dimensions of the 6, 7 and -8 series fuel tank designs.
I am not familar with RV4 fuel tank design dimensions so please keep that fact in mind and bear with me.

The technical answer to your first question is...yes...it is possible to install the end ribs at the same time. Accessability becomes an issue though, most particularily at the inboardmost rib location, an area where rib to rib spacing (RV8) is narrow. As shown in the photo on the left, the spacing is not much wider than the filler flange! Following installation of the end rib, inner access to the immediate area becomes severely limited and just reaching a lot of rivets can be a dark and difficult challenge. I suppose one could argue that some rivets could be accessed through the large cover plate hole in the side of the end rib but that approach seems comparatively more difficult to me. By leaving the end rib off for now, the builder enjoys much better illumination and the entire series of rivets attaching that inboardmost internal rib can be accessed and shot much easier, even comfortably, in reality making that rib the easiest of all the internal ribs to work. You lose that considerable advantage with the end rib installed.

Again, my comments do not reflect a familarity with RV4 fuel tanks. If you find that accessability is not an issue and falls within your personal comfort zone, then by all means install the end ribs the same time as all the others.



To help answer your question about prosealing the tips of the ribs, I refer you to my comments and detail photograph included
in post #40:

http://www.vansairforce.com/communit...2&postcount=40