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27iS - 04 fuel tube bend/flare?

jcboon

Member
I cannot figure out how to do this. In step 3 the flare is to be made first, and then the bend. That won't work with my bender.
But bend first and flare afterwards works. Just.

But I cannot figure out a way how to get the sleeve in place before bending or flaring. Any suggestions?

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It may not be possible to create that tube, 'K', using Van's dimensions. I was a beta-tester for a RV12is tubing kit that Aircraft Specialty is putting together. They have that tube, pre-bent and pre-flared. It fits perfectly. Talk to Steve at Aircraft Specialty.

The way they get the collar around those bends is to shorten the portion of the collar that goes through the 'B' nut.
 
It is not possible to do this exactly as per the directions while utilizing a standard bender and flaring tool.

For those of you who are fabricating this tube yourself....here is a trick that we sometimes use. If you shorten the collar to approximately half length or a little shorter, you can manipulate the collar around the bend into place.

The K tube is going to be one of the tubes we offer pre built, along with the E, F, G, H, and J tubes. The A and D tubes will have to be fabricated at the actual aircraft, and the B and C tubes are still in the decision making process. We are just awaiting test fitting results from a few beta testers at the moment and anticipate a full release sometime in late fall once data starts coming in from the early Powerplant kit recipients.


The K tube can be flared with the collar in place, but it requires a modified set of flaring dies. Here is a link to a video showing some of the rigid tube fabrication processes that Aircraft Specialty and TS Flightlines have been working on.

http://aircraftspecialty.com/howwemake.html

In the rigid tube video, the 17:55 mark shows the modified flaring dies to be able to flare with a full length collar in place.

This stuff is lots of fun, and we really have appreciated all the help from the early RV12iS builders to get this project jump started.

Take care and happy building,
Steve
 
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Steve and I have been working on this since last year, Oshkosh time. Mostly Steve and the beta testers, but its been a long process. Several of the beta testers had attempted to make these with common flaring tools and benders, but were having difficulties getting things to fit.

With the newly installed processes we have, Steve was able to make the tubes fit the fuselage. Steve posted the video of those processes. A couple of the tubes are a little problematic, not from a bending or fabrication point of view, but from an installation after the fabrication, AND the LARGE box needed to ship the pre bent--long tubes. I also understand that there is an edge-distance issue around some of the bulkheads that prevent pre-flaring the tubes on both ends with the nuts and sleeves. I havent seen this up close and personal, but I'm pretty sure we can find a way to do it. Gee--real time pics of this would be awesome if someone has them.

With the release of the engines, the testers should be able to finalize everything in a couple of months.

Thanks to all that helped to develop this package!!
Tom and Steve
 
A couple of the tubes are a little problematic, not from a bending or fabrication point of view, but from an installation after the fabrication, AND the LARGE box needed to ship the pre bent--long tubes.

Could you coil the long tubes for shipping, or would that be a problem because unless the builder unrolls them perfectly flat and straight, they would no longer be the exact length necessary for a good fit?
 
Mark,

That's a very good question. You are correct in that they would have to be unrolled EXACTLY perfectly for them to fit correct.

The issue is not the ability to bend the long lines. The issue is the fact that the long lines are impossible to install if they have already been bent into their final bent configuration.

The B and C lines we can fabricate and require just a bit of builder manipulation to put into place.

The E, F, G, H, J, and K lines pose no issues to install once bent into their final configuration.

The good news is that the longer lines are actually easier for a builder to fabricate in some ways because there is more play and leeway in them.

There is the potential of fabricating lines that could be installed before everything is riveted together, and we may explore that option in the future. However, since we don't have a 12iS fuse here to experiment with, we are planning on an initial release that will consist of the B and C lines,(most likely) and then all the lines in the aft end of the fuselage.

Steve and Tom
 
Thanks for the information and advise on the tubing. I like to bend and flare the tubes myself, and understand that I have basically two options. Either clut the sleeve, or make the bend half an inch lower/further from the tank. So that you can put the sleeve on the bent tube and then still flare it.

Do you know if there is an important reason from a space or perhaps fuel flow perspective against the idea of a bend half an inch lower?
 
Jeroen,

Unfortunately I do not know the answer to the question about the space and why Vans designed a tube with the bend that close to the flare. I don't know if there is any interference in that area, or if it is just the "optimal" tube routing that Solidworks came up with.

I know that the shortened collar trick works, but you have to be careful when tightening the nut that the collar is seated properly and protruding through the back of the nut.


I would ask those questions of Vans and let us know what their response is.


I think that you will see a variety of solutions to this in the field for builders that do fabricate them on their own, because as you found out, it is not possible to build and flare the tube as designed utilizing standard unmodified tooling. The dies that we had built to do close in flaring would be difficult to replicate on a standard hand flaring tool without extensive modification to that tool.


Happy building!

Steve
 
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Being able to see the fuselage first hand is a big help. Sometimes, even having the plans you can get a good perspective of whats around the area where you are working.

Tom
 
Thanks for the information and advise on the tubing. I like to bend and flare the tubes myself, and understand that I have basically two options. Either clut the sleeve, or make the bend half an inch lower/further from the tank. So that you can put the sleeve on the bent tube and then still flare it.

Do you know if there is an important reason from a space or perhaps fuel flow perspective against the idea of a bend half an inch lower?

There are other options

The bend is only 45 deg if I recall correctly.
There is a huge difference between bending a tube 45 deg and bending it 90 Deg. A 45 degree bend can be done by hand in a relatively tight radius without causing it to reduce in cross section (it actually will very slightly but it grows in the opposite direction so the overall cross section area doesn't change). More than 45 degrees at this tight of a radius does require use of a tool.

Instead of shorting the sleeve (not something I ever recommend), use the parts unmodified. Temporarily install an AN fitting on the end of the flared line ( a straight bulkhead fitting works best for this). The purpose of the fitting is to temporarily add length to provide leverage for bending by hand.
As mentioned, when only bending 45 deg., this will work fine.

Give it a try with a small piece of scrap tubing. You may be surprised.
 
I highly recommend these - a low cost, easy to use tool set to have the tool bin:

General Tools S106 Tubing Bender Set https://www.amazon.com/dp/B00004T827/ref=cm_sw_r_cp_tai_uu-sBbM08W6HE

It makes bending tube in tight places and by had an easy task without any marring and ending up with a nice, round tube. Slide one inside the tube, another over the outside of the tube, grip with hand and bend.

That is another option, but I have had nothing but bad experiences trying to use them, but I might just be that I don't know what I am doing.........
 
Ditto with those. I gave up on them after having some tube become permanently trapped inside them.

In my opinion, they're worse than worthless - they steal tube from me.

Dave
 
Interesting feedback. Personally, I’ve been pretty successful with them. I recently formed just about every line on my RV-12 with them that needed to be done in place. I do recommend lubricating the inside of the outer tool and outside of the inner tool with tool oil before use; maybe that’s the difference. I’ve used them on 3003 and 5052 without issue. Definitely not good for harder lines, such as stainless.
 
Back in my po' boy days, we used to fill the tubes with mason sand, cap the ends and bend free hand. After bends and final flare, a good flush with liquid, a little air, and you were in business.
 
I used a bending tool I got at the OSH Flymarket that prevents ovalization. It has a a series of grooves for each tube OD and a lever that when pulled down forces the tube around the hub trapped between the grooves that prevent ovalization. I think it cost $10 and works like a champ. Bending tubing was a non-issue with it.
 
Sometimes optimal weight and traditional aircraft mandates can be sacrificed on the alter of practicality and maintainability. Flexible Teflon hose within braided stainless shielding is way more impact and wear resistant than the run of the mill soft aluminum tubing in your kit. The hose ends are heavier but easier to deal with than bending and flaring tools regardless of make and quality.

All this can be purchased from any of the aircraft suppliers or any of the race car suppliers (at half the cost) that carry the Aeroquip line, which most of them do. Below is a link to an example;

http://aeroquipperformance.com/lookup.html?supercat=11&category=42

I'm sure others, some with vested interests will disagree, but beyond weight and expense the Teflon SS braided hose and end fittings are superior on almost all respects to bent aluminum tubing. Look in your firewall forward kit and see how much unbent aluminum tubing is included.

There are many others that supply the same items and quality as Aeroquip and there is an active forum member that markets a complete line of exactly what I'm describing. I'm sure he will be glad to make you any Teflon flexible line you might want for a reasonable price.
 
For most RV-12 builders, hoses aren?t an option. Because we are registering our planes as ELSA, the aircraft must be built according to the plans. After certification, you can switch to hoses, but at that point you?ve already installed the tubing specified by Van?s, so that?s not likely to happen. Other RVs and RV-12s registered as E/A-B do not have to meet this requirement.
 
Sometimes optimal weight and traditional aircraft mandates can be sacrificed on the alter of practicality and maintainability. Flexible Teflon hose within braided stainless shielding is way more impact and wear resistant than the run of the mill soft aluminum tubing in your kit. The hose ends are heavier but easier to deal with than bending and flaring tools regardless of make and quality.

All this can be purchased from any of the aircraft suppliers or any of the race car suppliers (at half the cost) that carry the Aeroquip line, which most of them do. Below is a link to an example;

http://aeroquipperformance.com/lookup.html?supercat=11&category=42

I'm sure others, some with vested interests will disagree, but beyond weight and expense the Teflon SS braided hose and end fittings are superior on almost all respects to bent aluminum tubing. Look in your firewall forward kit and see how much unbent aluminum tubing is included.

There are many others that supply the same items and quality as Aeroquip and there is an active forum member that markets a complete line of exactly what I'm describing. I'm sure he will be glad to make you any Teflon flexible line you might want for a reasonable price.

Vernon and All,


Tom and I have been supplying conductive Teflon hoses for a long time and they are a viable and easy to install option for many builders.

However, we also recognize that there are situations where a flexible conductive Teflon hose is not the ideal solution. For this reason we have invested very heavily in rigid tube equipment. Over the last two years we have set up full CNC tube bending capabilities as well as a coordinate measurement machine which integrates with our tubing bender. This allows us to reverse engineer tubes and build them with extremely high precision.

In doing these upgrades, we are able to offer builders Flex hoses where they make sense, rigid tubes where they make sense, and in some cases a rigid to flex combo hose as we have done with the rv 7-9 Andair Setup and a few others that have not yet been officially announced.

In the case of the RV12iS, we recognize that a lot of builders will want to fabricate their own tubes. Other builders will want to have the option of pre bent (and possibly even pre flared) tube assemblies that they can install right out of the box. Because most builders will want to go the ELSA route, the use of Teflon flex assemblies for this aircraft would not be a viable alternative, unless it is being built as an EAB.

Have a great week and happy building
Steve
 
Van's has finally begun shipping Engine kits and we have now been able to do fit verification tests on our CNC bent Rigid Tube kit for the RV-12iS.


AS Flightlines has decided to offer the F12127E, F, G, H, J, and K lines. They will come pre bent and pre flared. The cost of the kit is $324.95, and we will be happy to buy back the unused AN Nuts and Sleeves from customers for $25 that won't be needed if you purchase this package.

In addition, we will offer the F12127B and F12127C lines for those customers that have not yet completed the bottom skin installation in Section 21. These tubes need to be slid through the bulkhead into place and then flared by the customer due to going through a grommet. The only way to offer these lines pre bent is to install them at this point in the build. These tubes will add $75 to the cost of the above package.

Below are some pictures of the pre bent tubes as well as what they look like once installed.

If you would like to see the design/fabrication process of these tubes, more information can be located at http://aircraftspecialty.com/howwemake.html under the "Rigid Tube" Section.

Have fun building!!!

Steve and Tom

RV-12iS%20Pre%20Flared%20Tube%20Kit.jpg



Installed%202.jpg


Installed%201.jpg


F12127BC-1.jpg


F12127K.jpg
 
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