Good morning. Congrats on getting your project started!!!!!
These are all great questions and make for a very interesting discussion.
Let's start off with the rigid tube question. The stock kit comes with 3003 tubing. This is a soft and easy to form aluminum that comes in a roll. You straighten it out, bend it into final configuration and flare it. 5052 aluminum is a bit harder to work with as it is a bit stronger and harder to bend. We purchase it in straight sticks, cut it to length, and then fabricate lines with it.
If you go to the following link and click on "Rigid Tubes", you can see the start to finish process of how we fabricate these. It's a long video, but the 11:30 mark is where we show the actual bending of some RV14 tubes.
Next, we move on to hoses. In an aircraft where you have fluid that "flows", you want to utilize a CONDUCTIVE TEFLON hose. This ensures that your hoses will not deteriorate over time due to static discharge to the stainless braid causing pinhole leaks in the hose liner. A google search provides more information on that topic.
The stock Van's kit and FWF hose package utilizes conductive teflon hose assemblies for both the Fuel and Oil lines for the stock configuration engine.
Our FWF packages are similar to the stock Vans package in several ways. There are three main differences.
1. The first is that we utilize conductive teflon lines with Stainless fittings on ALL firewall forward lines. This includes oil pressure, fuel pressure and manifold pressure.
2. Second, we firesleeve all our Firewall forward lines (Manifold pressure is optional). We do NOT exclude firesleeve from Oil lines, fuel pressure, or oil pressure lines)
3. Finally, the third difference is that we build our hoses to the EXACT firewall forward configuration that our customers are utilizing. A Thunderbolt engine with an FM150 servo utilizes a different hose setup than the stock IO-390. If you are using a backup alternator, or an upright oil filter adapter, this necessitates a change to some line lengths. Also, a single or dual pmag setup creates another variable that requires FWF hose changes. Basically, we build everything custom and to order and as such are able to ensure that the hoses for your specific aircraft will be a perfect fit.
For more information on the hoses and how they are fabricated, you can go to the same link.....
Click on Conductive Teflon Hoses.
Regarding hose sizes.....
-3 - We utilize these for the cabin and gear brake lines. These are utilized for compact routing and great bend radius flexibility.
-4 - These are utilizes for Fuel and Oil Pressure lines, and well as servo to spider fuel distribution lines
-6 - These are typically the fuel lines for an aircraft
-8 - This is the size of the oil lines utilized
As far as fabricating your own assemblies.......the key is to ensure that you are utilizing a high quality conductive teflon hose assembly. That's very important. Also, if you are able to find someone who can do a hydrostatic pressure test on the hose assemblies once complete, that would give you peace of mind that they are perfectly built.
Please feel free to reach out to Tom or I if you have any questions. If you want to go the "build your own" hose route, we would be more than happy to help point you in the right direction and answer any questions that you have.