Oxygen System for Phoenix

[Dave]

I'm interested in how other owners have chosen and installed 2-place oxygen systems in their Phoenix motorgliders.  I have done some mountain wave soaring in the past in my pure glider and always restricted my altitude due to no O2 system. I'm also considering some touring in high altitude environments and want to be safe and comfortable.

Thanks for your input, and Happy New Year to all.

Dave Glosser

[mikeschumann]

I mounted a cylinder horizontally under the shelf, inside the baggage compartment behind the seats.  See the attached LOA for pictures and complete details.

I like this arrangement better than mounting the bottle vertically attached to the bulkhead behind the pilot seat for a couple of reasons:

1.  The bottle is much easier to get at, both to remove to refill, as well as to turn the valve on and off.
2.  The bottle is an Aluminum cylinder with no life limits.  It has enough capacity for 5+ hours with 2 pilots at 18K ft.
3.  The cylinder is very inexpensive (it's basically a D size standard medical cylinder)

The tubes to the MH O2 demand controller are routed from the regulator on the cylinder thru a gap between the pilot seat and the shelf frame behind the pilots left shoulder, so no drilling is required for the tubing.  The standard MH tubing is long enough to go behind the pilot seats to the O2 demand controller(s), which I have sitting on the arm rest between the two seats.

The only thing I might change, is to use the short mounting feet, instead of the tall ones.  There should be enough clearance between the shelf reinforcements and the bottle.  This would provide ~1" of additional vertical clearance for loading baggage, which doesn't sound like much, but could make life a little simpler.

Feel free to contact me if you have any questions.

Phoenix O2 LOA.pdf

[Dave]

Hi Mike,

That looks great. Thanks for the quick help.

Dave

[Jim Lee]

Hi Dave,

The standard installation is the Mountain High system, CFF480/O2D2 is MH item # 00EDS-2084-02  .  The cylinder is mounted in the baggage compartment and photos are available on the website.  I can order the system for you or you can order it directly from Mountain High.  Some other mounting solutions have been used by a couple of owners, but in my mind they are inferior to the standard setup in weight and complexity. 

Jim

[edwalker]

Hi, Dave -

I agree with the advice so far, but let me add one alternative. I've had some medical issues that made me decide that I wanted to have immediate access to the cylinder, so I mounted mine on the top of the shelf with the O2D2 unit in the side pocket of the left seat. Yes, I lost some storage space, but I am able to turn the cylinder on if I need it unexpectedly and can track the pressure with a glance. I've had a couple of times where I chose a higher altitude over the mountains or pursued a wave opportunity that I had not foreseen during my preflight planning, and if I had the cylinder in the baggage compartment I would have had a problem if it were not turned on. Eric designed a flexible valve rod that allows him to turn it on and off, but I don't believe he can monitor the gauge.

Just go where your comfort zone is - mine was driven by medical safety concerns. If you live in the flatlands unplanned O2 use is probably rare. However, in my neck of the woods opportunities for O2 use present themselves unexpectedly and more frequently than I had expected. If you can deal with the lack of access or be disciplined about planning and preflight then the bulkhead/baggage areas should be fine.

Ed

 

[mikeschumann]

I had an extensive discussion with Jim Lee about this alternative.  His big concern, which I believe is legitimate, is in the event of a crash, the oxygen cylinder could break loose from its mountings and become a threat to the pilot and passenger's heads.  That's the main reason that I elected to mount the cylinder under the shelf, behind the seats.

The other thing you need to keep in mind is that the shelf itself is very thin material.  However, the underside of the shelf has carbon fiber reinforcements for the shoulder harnesses running to the rear of the aircraft.  In my installation, the metal plate on the top of the shelf forms a sandwich with the cylinder around the middle shoulder harness shelf reinforcements, preventing the cylinder from becoming a loose object in the event that the shelf fails during a crash.

If I was flying regularly out west, I would turn on the cylinder valve for each flight.  The MH regulator and controllers don't leak when not in use, so this shouldn't result in any excessive O2 usage.  In my installation, the shutoff valve is right behind the pilot seat, so it is very easy to get at while preflighting the aircraft..

[Dave]

Thanks gents. This is all good material. I believe I'll go with the MH under shelf mounting system.

Dave

[discus239]

Jim supplied my system, used it every flight this past summer, recently read it is not enough to close the valve between flights, the line must be depressurized, there are parts in the controller that don't like being under pressure full time.