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Dana

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When I needed to extend the brake lines on my Starduster I bought the teflon lined hoses with stainless steel braid from Summit Racing... yes, 37° flare, the racing guys all use AN fittings. They weren't very expensive. Looks like my Hatz has the same hoses.

Going back to post #1 and parking brakes... the standard setup is a valve that's closed while the brakes are applied. Those valves are expensive and I'd have to replumb everything. I've been thinking about a cable setup with an overcenter draw latch to pull on the levers. I can use the hole in the lever meant to connect it to pedals in the front seat which is unused on my plane, no brakes for my passenger.
 

Dan Thomas

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Sep 17, 2008
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5,606
Sadly, nylon too grows brittle with age, though some use it for brake lines.
Yes, it will, but if you use black it lasts far longer. It's UV resistant, as it has to be when it's used on truck air brake systems. Those trucks have nylon tubing all along the frames and coiled nylon hoses between the tractor and trailer, out in the sun all day for years at a time, and those aren't even black. They're green and red, for service and emergency lines. If a nylon hose rubs up against the frame rail it will get dirt embedded in it and cut into the rail. Saw that in the 70s shortly after nylon replaced copper on trucks. It's tough stuff. On my airplane, as I said I had it for over 20 years without any failure and it was still supple when I sold the airplane. The airplane was hangared, though, for 16 years and out in the sun for another five.

Rubber hoses also suffer from the elements. The fabric deteriorates in the sun and rain and dirt. The steel braid starts rusting. The rubber hardens with age, chemical attack and ozone. I rebuilt over 50 hoses on a single transport-category airplane and found all of that. Some of them were as hard as wood. Most were seeping oil.

Aluminum lines corrode and will fatigue if asked to flex repeatedly. They are subject to abrasion and mechanical damage if not protected.

There are no perfect systems. One uses what he has to. For certificated airplanes you use what's specified in the parts manual. For homebuilts you can use other stuff; you're the builder and test pilot. I used nylon tubing because it was inexpensive and light and compact and I was VERY familiar with it, having been a shop foreman in an air brake remanufacturing shop for 12 years. I used that stuff in numerous production and test machines I designed and built for the plant. WHen I used it for brake tubing I checked it at each annual and found no reason to replace it.

I plumbed our new house for a basement bathroom. I used PEX, as the builders had used everywhere else. Half-inch PEX is rated at around 160 PSI at room temperature. I was concerned about the fitting attachments, since the fittings only have a couple of tiny ribs to grip the tubing and the clamp ring holds it all together. I took a foot of that PEX and clamped a PEX plug in one end and an NPT fiitting in the other. Took it to work at the airport and filled it with 5606 and connected it to the hose tester. Covered it well with rags. Pumped the pressure up. At 910 PSI it blew. The tubing had swelled and split; the fittings hadn't moved. Showed the inspector what I'd done and he took it back to the office to show the other guys. They had also wondered what pressure that stuff was good for.

PEX's rating drops with hot water. I didn't test it hot.

Edit: I should also point out that the tubing many call nylon is not nylon. A lot of tubing is polyethylene or vinyl, and those suffer worse with age and UV and chemical attack that nylon does. They also won't take high pressures. I've seen those plastics deteriorate fairly rapidy with fuel in them. I wouldn't even use nylon for fuel. Even the low- and medium-pressure hoses approved for fuel in certificated airplanes are normally recommended for replacement every five years.
 
Last edited:

Dan Thomas

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Joined
Sep 17, 2008
Messages
5,606
When I needed to extend the brake lines on my Starduster I bought the teflon lined hoses with stainless steel braid from Summit Racing... yes, 37° flare, the racing guys all use AN fittings. They weren't very expensive. Looks like my Hatz has the same hoses.

Going back to post #1 and parking brakes... the standard setup is a valve that's closed while the brakes are applied. Those valves are expensive and I'd have to replumb everything. I've been thinking about a cable setup with an overcenter draw latch to pull on the levers. I can use the hole in the lever meant to connect it to pedals in the front seat which is unused on my plane, no brakes for my passenger.
When I restored the Jodel I machined a twin shutoff valve for the brake system. It worked, but I had to get into the airplane, stomp the brakes and pull the control cable to close the valve. A pain to do that, since I had to climb out again to hand-prop it. I took it out after a few years and used a heavy vernier PTO control cable to pull the top of a lever ahead of the firewall that had a length of the same music wire attached to its lower end. The wire went through the firewall and pulled 1/16" cables that pulled the heel brake levers forward. I could reach into the cockpit, pull the big knob, then twist it a few times to the left to use the vernier action to really snug the brakes on good.
 

Speedboat100

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Even do, he was very perspective.


BJC
I think Otto Lilienthal and Leonard Bonney both tried to imitate birds too much. Not to say birds aren't the ultimate fliers in our solar system, but later developements did reveal some new ways to comprehend flight more teorethically correct.



bonney.jpg
 

120mm

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Oct 13, 2020
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I think Otto Lilienthal and Leonard Bonney both tried to imitate birds too much. Not to say birds aren't the ultimate fliers in our solar system, but later developements did reveal some new ways to comprehend flight more teorethically correct.



View attachment 104754
The Wright Brothers also imitated birds, but were the first to understand where birds' stability and control came from, and realized that stability and control were the Hokey Pokey of aviation.

This book does a good job of describing the process:

1606745273649.png
 

BBerson

Light Plane Philosopher
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Port Townsend WA
The Wright's were concerned with control. Not so much for stability. They figured stability was up to the pilot, same as a bicycle.
 

jedi

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Sahuarita Arizona, Renton Washington, USA
I think Otto Lilienthal and Leonard Bonney both tried to imitate birds too much. Not to say birds aren't the ultimate fliers in our solar system, but later developements did reveal some new ways to comprehend flight more theoretically correct.
........
Specifically what are you referring to with the phrase "but later developements did reveal some new ways to comprehend flight more theoretically correct."
 
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