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jorgen.nielsen(at)mweb.co
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 Posted: Sun Oct 17, 2010 1:07 pm Post subject: L29 air system mod |
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Been some discussion around the air system - Jean shared his compressor modification which is great.
For those wanting to do the same, one could use an old Cornelius compressor - its a 3 stage driven by an 24V electric motor. People used to buy them surplus and rig up homebrew compressors, some googling should reveal more.
From a ground handling perspective the Achilles heel of the L29 is the air system - if you flying away somewhere, its necessary to send air ahead by road, or arrange air at the destination - either scuba air or Nitrogen, both work perfect. I have done this!
To get around this, I also came up with an idea and made a modification which has worked trouble free now for 3 years.
I never fly above 20,000ft so do not need oxygen. I therefore replaced the oxygen tanks with additional "normal" tanks. Lets call the standard system the "A" tanks, and the additional set the "B" tanks. Each set of tanks has a shut off valve which then goes into a t-fitting - the middle of which feeds the aircraft air system. So one or both valves has to be open for flight. Operation is simple - if its a local flight open say the "A" system valve, check pressure, add air if required and fly. After the flight, close the valve. All the air stays in the tank as there are no losses downstream.
For away flights, I open both valves, fill up the system, close off say the "B" system, and fly. On landing, I shut off the valve. I can then leave the aircraft, knowing that when I return it has not lost any air. I can fly several sorties, all on the first "A" set of tanks. And I still have a full set of "B" tanks. So when the first set gets low on pressure, I simply use the other set.
It works great. I made one away trip about 2 months back where I flew to destination, flew 3 sorties, and flew back, several days later. And still had lots of air.
The other great thing about this mod is that the standard system has 8l of air, the secondary system has 12l. So the mod takes the air carried on board from 8l to 20l in total ( or to be precise from 1200l to 3000l at 150 bar) , and the ability to shut off the tanks means no lost air when on the ground.
You have to remember to open a set of tanks before flight - I preflight in the normal way, and open the air system then check in the rear cockpit that not only the main air system is ok, but also the backup air. After start, my final pre-taxi check is the pneumatic pressure - I then roll forward and check brakes, and re-check pneumatic pressure. There should be no change. If you open the air, then close it again, the gauge will drop about 20-30 bar from one brake application.
Regards Jorgen
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delfin_driver(at)yahoo.co
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| Posted: Mon Oct 18, 2010 6:51 am Post subject: L29 air system mod |
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What type of high pressure shut off valve is used. Must be relialbe to avoid leaking
From: Jorgen Nielsen <jorgen.nielsen(at)mweb.co.za>
To: l29-list(at)matronics.com
Sent: Sun, October 17, 2010 4:04:38 PM
Subject: L29-List: L29 air system mod
Been some discussion around the air system - Jean shared his compressor modification which is great.
For those wanting to do the same, one could use an old Cornelius compressor - its a 3 stage driven by an 24V electric motor. People used to buy them surplus and rig up homebrew compressors, some googling should reveal more.
From a ground handling perspective the Achilles heel of the L29 is the air system - if you flying away somewhere, its necessary to send air ahead by road, or arrange air at the destination - either scuba air or Nitrogen, both work perfect. I have done this!
To get around this, I also came up with an idea and made a modification which has worked trouble free now for 3 years.
I never fly above 20,000ft so do not need oxygen. I therefore replaced the oxygen tanks with additional "normal" tanks. Lets call the standard system the "A" tanks, and the additional set the "B" tanks. Each set of tanks has a shut off valve which then goes into a t-fitting - the middle of which feeds the aircraft air system. So one or both valves has to be open for flight. Operation is simple - if its a local flight open say the "A" system valve, check pressure, add air if required and fly. After the flight, close the valve. All the air stays in the tank as there are no losses downstream.
For away flights, I open both valves, fill up the system, close off say the "B" system, and fly. On landing, I shut off the valve. I can then leave the aircraft, knowing that when I return it has not lost any air. I can fly several sorties, all on the first "A" set of tanks. And I still have a full set of "B" tanks. So when the first set gets low on pressure, I simply use the other set.
It works great. I made one away trip about 2 months back where I flew to destination, flew 3 sorties, and flew back, several days later. And still had lots of air.
The other great thing about this mod is that the standard system has 8l of air, the secondary system has 12l. So the mod takes the air carried on board from 8l to 20l in total ( or to be precise from 1200l to 3000l at 150 bar) , and the ability to shut off the tanks means no lost air when on the ground.
You have to remember to open a set of tanks before flight - I preflight in the normal way, and open the air system then check in the rear cockpit that not only the main air system is ok, but also the backup air. After start, my final pre-taxi check is the pneumatic pressure - I then roll forward and check brakes, and re-check pneumatic pressure. There should be no change. If you open the air, then close it again, the gauge will drop about 20-30 bar from one brake application.
Regards Jorgen
[quote]http://www.matronics.com/contributi==============
[b]
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