Oxygen M20K

[RoboZoom]

Hi,

 

I'm an experienced military 'heavy' pilot and I'm trying to make a foray into basic civil aviation.  In my searching, I've decided that the Mooney M20K with the Rocket conversion seems to fit my needs perfectly (essentially a cross country machine making 1000NM trips feasible).  

 

Being a total novice in civil aviation with anything more complex than a C-172, I saw that the Mooney's ceiling is FL240 and has a built in Oxygen system.  I was wondering how the oxygen was delivered (do masks normally come with the airplane?), how long it lasts, and what you all think of it's high altitude cruise capability.  Is there built in Oxygen for passengers as well?  

 

Any thoughts are welcome.  Thanks!

[DonMuncy]

There is usually oxygen ports for everybody, but unless you ask the owner, there may or may not be masks still with the plane. (There were none with mine).

How long the O2 lasts is highly variable, depending on number of users, type of cannulas or masks, how high you are flying, and the individual consumption (varies between individuals). I have never had a problem making a 1000 nm trip, but usually flew between 14 and 17,000, with 2 people.

[RoboZoom]

I will certainly follow up with the seller, but just wanted to clarify that there usually are 2 ports?  Or 4 ports?  

[Jeff H.]

Verify factory or aftermarket.  My 231 Rocket with factory air has one port at the pilot location and three just behind the pilot seat.

[DonMuncy]

Same for mine. 1 and 3.

[jlunseth]

The fittings are pretty much standard. Try Precise Flight. You are going to want a miked mask at least for the pilot station.

[manu damaschin]

4 posts in ine as well...

[Houman]

Not all of them come with built in O2, mine has a portable tank, which is fine and as for mask and canula, I would imagine you want to get new ones as they are cheap if you have the regulator, since it is more of a personal item ( I don't want anything that has gone in anyone else's nose )...

What I find expensive is the refill, what you save in fuel by going high, you kind of spend in O2 refilling, unless you build your own refill station, something that I'm looking into right now.

btw, enjoy the rocket, it sure flies fast for a civilian single piston...

[aviatoreb]

Mine also does not have built in O2.  Actually I like it that way since, a) it gives me weight and balance flexibility to better fill the seats on short flights, and I live rurally and fly from a rural airport where filling the O2 would be a pain if not portable.  But I have made an arrangement with a local gasses company where I bring them my empties.

 

Whether built in or portable I highly recommend a few things.  An O2D2 extends the use of your O2 tank dramatically.  I flew all summer on one of my two M sized O2 portable bottles with that O2d2, including a round trip to colorado and several other good sized trips.

 

ALso a quality mask with built in mic is made by Alps.

 

Also for cannula I love the oxyarm - much less obtrusive.  Plus if you wish you can replace just the tips.  I bought several oxyarms from a medical supply website for $6 each even though they are something like $100 each for the "aviation version" which is identical.

[chrisk]

Mine is built in and configured as 1+3.  I don't try to conserve O2.  For two of us, a 1000 mile round trip has not been an issue.  I have a full face mask, but I don't really care for it.   For O2, there are several different connectors for different planes.  Mine are Scott, and it is likely that is what you will get with a Rocket with built in O2.

 

Other O2 things.  An O2 system can be expensive if the tank needs to be replaced.  And some tanks need to be retired after a certain number of years.

[FlyDave]

Also for cannula I love the oxyarm - much less obtrusive.  Plus if you wish you can replace just the tips.  I bought several oxyarms from a medical supply website for $6 each even though they are something like $100 each for the "aviation version" which is identical.

 

Eric,

 

I got the medical OxyArm cannulas and have only used them a couple of times. I really like them from a comfort and usability standpoint but I found that my o2 usage was much higher (~40% higher) using OxyArm over the OxySaver (mustache type) cannula. Have you found this as well?

 

Dave

[aviatoreb]

Eric,

 

I got the medical OxyArm cannulas and have only used them a couple of times. I really like them from a comfort and usability standpoint but I found that my o2 usage was much higher (~40% higher) using OxyArm over the OxySaver (mustache type) cannula. Have you found this as well?

 

Dave

 

Hi Dave,

 

Oxysaver is an efficiency system to use less - oxyarm is just an open flow cannula that happens to attach to your headset for comfort instead of around your ears like regular cannula.  So that 40% is the efficiency benefit of oxysaver over any open flow cannula.

 

I do not experience that 40% penalty since I use O2D2 together with my oxyarm - O2D2 is even more efficient than oxysaver (but I have not run it both ways to quantify) - so oxyarm+o2d2 I claim will use even less O2 from your bottle than oxysaver alone.  Plus more comfortable.

[David Mazer]

If your looking for a Rocket, mine is for sale, http://mooneyspace.com/topic/10618-fs-1986-252-m20k-rocket/?hl=%2B1986+%2Bm20k

 

I have the built in oxygen (1+3) and recently took a 4 hr flight at 18,000, 1050 miles, 4:21 min and used about 400 psi of 1600 with one pax.

[RoboZoom]

All,

 

Thank you for the tips.  This will definitely help me going forward!

 

One more question - forgive my ignorance, but are cannulas a suitable replacement for masks? How high are they suitable?  Thanks!

 

Re David:  That plane looks beautiful but sadly it's a bit out of my price range.

[aviatoreb]

All,

 

Thank you for the tips.  This will definitely help me going forward!

 

One more question - forgive my ignorance, but are cannulas a suitable replacement for masks? How high are they suitable?  Thanks!

 

Re David:  That plane looks beautiful but sadly it's a bit out of my price range.

 

Above 18k you are required a mask - Its in the regs:

23.1447

http://www.ecfr.gov/cgi-bin/text-idx?c=ecfr&sid=38a6e86e7896914a4e0496b0cde8542c&rgn=div8&view=text&node=14:1.0.1.3.10.6.104.49&idno=14

 

© If certification for operation above 18,000 feet (MSL) is requested, each oxygen dispensing unit must cover the nose and mouth of the user.

[GeorgePerry]

Hi,

 

I'm an experienced military 'heavy' pilot and I'm trying to make a foray into basic civil aviation.  In my searching, I've decided that the Mooney M20K with the Rocket conversion seems to fit my needs perfectly (essentially a cross country machine making 1000NM trips feasible).  

 

Being a total novice in civil aviation with anything more complex than a C-172, I saw that the Mooney's ceiling is FL240 and has a built in Oxygen system.  I was wondering how the oxygen was delivered (do masks normally come with the airplane?), how long it lasts, and what you all think of it's high altitude cruise capability.  Is there built in Oxygen for passengers as well?  

 

Any thoughts are welcome.  Thanks!

 

The rocket is a very capable aircraft although you'll want to do some research and make sure you have a thorough understanding the complexities of a high performance "big bore" turbo and the operating costs.  Turbo charged engines typically require the pilot to pay close attention and use proper engine management techniques to ensure longevity and reliability.  Also, any aircraft that is turbo charged will need "more" maintenance and the fuel costs will be higher when compared to its normally aspirated counterpart.

 

As for the O2 question, you can use cannulas up to 18K.  Above that you should be on a mask.  Before you run out an buy a a "fly-it-high turbo" try flying with a mask.  Some pilots can't stand flying with a mask on.  I don't mind the cannulas, but almost never go above 18K b/c I don't want to put on the mask.  Also if your going to be at high altitudes (>12K) for any length of time you should also purchase a pulse oximeter (PO).  The PO allows you to check your blood O2 saturation periodically throughout the flight.  Anything less than 90% is bad and is an indication that something with either the delivery system or your personal physiology isn't working as it should.  Less than 90% means you should not continue at that pressure altitude and need to descend in order to increase atmospheric pressure and help you lungs better absorb the O2 your brain and body needs.   

[Z W]

Most piston single aircraft are not regularly flown over about FL200.  I would bet that most are flown at FL180 or below almost all of the time.  Above FL180 your useful time of consciousness declines sharply:

 

http://en.wikipedia.org/wiki/Time_of_useful_consciousness

 

Altitude in Flight level Time of Useful Consciousness

 

FL 150 30 min or more  

FL 180 20 to 30 min 

FL 220 5-10 min 

FL 250 3 to 6 min 

FL 280 2.5 to 3 mins 

FL 300 1 to 3 mins

FL 350 30 sec to 60 sec 

FL 400 15 to 20 sec 

FL 430 9 to 15 sec 

FL 500 and above 6 to 9 sec

 

As you can see, at FL220, you've only got 5 or 10 minutes of consciousness if you develop a problem with your O2, vs 20-30 minutes at FL180.  It gets worse as you go up.

 

In a GA single, you generally only have one O2 system and one pilot.  No redundancy.  In theory you could carry a back-up tank, but that's a lot of hassle, and there's no warning built in to tell you to switch to your backup, unlike loss of pressurization in a larger aircraft.  One kinked line or problem with your O2 delivery and you can be lights out pretty quick.

 

Also, in my experience, there isn't much weather that can't be topped at FL180 that you're going to top by going to FL200 or FL220.

 

I think what many of us do is stop at FL180 and stick to the cannulas.  They're more comfortable anyways. 

[chrisk]

Before you run out an buy a a "fly-it-high turbo" try flying with a mask.  Some pilots can't stand flying with a mask on.  I don't mind the cannulas, but almost never go above 18K b/c I don't want to put on the mask..   

 

My most recent trip was around 4 hours.  Trust me, the mask gets old after 2 hours.  My glasses just don't fit well with the mask, and the mask seems to accumulate moisture.   But I'm not sure the cannulas are any better.  They tend to dry out my nose.

 

And a pulse oximeter is very cheap and useful.  Friday, after about 4 hours at 10,000 (west bound), my wife started to complain about a headache.   I checked her levels and she was around 80.  It's why I use O2 at lower levels.   Her other problem was the lack of hydration, due to personal choices.  I on the other hand drink often and have no issues with "Travel John" type products.  --Only relevant because your likely in for a long trip if your climbing to altitudes where a mask is needed.

 

On Sunday, we were headed east at 19,000 for a 750+ mile trip. The faster speeds, no vfr traffic, and not having to mess with the altimeter are some of the advantages that make up for the hassle of a mask.

[aviatoreb]

Most piston single aircraft are not regularly flown over about FL200.  I would bet that most are flown at FL180 or below almost all of the time.  Above FL180 your useful time of consciousness declines sharply:

 

http://en.wikipedia.org/wiki/Time_of_useful_consciousness

 

Altitude in Flight level Time of Useful Consciousness

 

FL 150 30 min or more  

FL 180 20 to 30 min 

FL 220 5-10 min 

FL 250 3 to 6 min 

FL 280 2.5 to 3 mins 

FL 300 1 to 3 mins

FL 350 30 sec to 60 sec 

FL 400 15 to 20 sec 

FL 430 9 to 15 sec 

FL 500 and above 6 to 9 sec

 

As you can see, at FL220, you've only got 5 or 10 minutes of consciousness if you develop a problem with your O2, vs 20-30 minutes at FL180.  It gets worse as you go up.

 

In a GA single, you generally only have one O2 system and one pilot.  No redundancy.  In theory you could carry a back-up tank, but that's a lot of hassle, and there's no warning built in to tell you to switch to your backup, unlike loss of pressurization in a larger aircraft.  One kinked line or problem with your O2 delivery and you can be lights out pretty quick.

 

Also, in my experience, there isn't much weather that can't be topped at FL180 that you're going to top by going to FL200 or FL220.

 

I think what many of us do is stop at FL180 and stick to the cannulas.  They're more comfortable anyways. 

 

I am not doubting the table but it confuses me in the following way.  Can someone with proper aeronautical medical knowledge answer the following seeming paradox?

 

Ok Table says that at FL50 you get 6 to 9 seconds of useful consciousness.  But I can go underwater at my pool and hold my breath for 2 to 3 minutes - when I was a kid and I used to practice that I got up to 5 minutes.  So if I can hold my breath for 2 minutes at least - why at FL50 do I only get 6 to 9 seconds?  Again - I am not doubting - I am confirming I am confused.  Please explain.

[N201MKTurbo]

If you hold your breath, the air in your lungs has an oxygen partial pressure the same as sea level. If you fill your lungs with air at the pressure of FL500 the oxygen partial pressure would be very low.

 

If you filled your lungs with pure oxygen at FL500 you would be able to hold your breath for some time. It would still be less then air at sea level because the oxygen partial at FL500 with pure oxygen is less then the partial pressure at sea level with 21% O2.

[Z W]

I'm no physician, but I suspect that holding your breath results in your body continuing to process oxygen held in your lungs.  When you continue to breath air that contains no oxygen, you are expelling that good oxygen.  Compare it to breathing out all of your air, and then going underwater.  I doubt you would make it 5 minutes.  Pretty sure I wouldn't.

I agree that 6 to 9 seconds sounds extreme.  But what do I know?  Maybe there are other factors.  I also hope somebody with some medical knowledge can chime in.

[Super Dave]

I am not doubting the table but it confuses me in the following way.  Can someone with proper aeronautical medical knowledge answer the following seeming paradox?

 

Ok Table says that at FL50 you get 6 to 9 seconds of useful consciousness.  But I can go underwater at my pool and hold my breath for 2 to 3 minutes - when I was a kid and I used to practice that I got up to 5 minutes.  So if I can hold my breath for 2 minutes at least - why at FL50 do I only get 6 to 9 seconds?  Again - I am not doubting - I am confirming I am confused.  Please explain.

 

Trying to hold your breath through a rapid decompression at 50,000' could cause a lung rupture. Also, at the lower altitudes we can hold our breath or just stop breathing altogether, but our bloodstream still holds a significant amount of dissolved oxygen to supply our brain. At altitudes like 50,000' the lack of pressure causes the reserve of dissolved oxygen to quickly outgas, leaving our bloodstream without sufficient oxygen to supply our brain. Forgive me for any incorrect terminology, I'm trying to remember this stuff from a long ago aeromedical course.

[N201MKTurbo]

If you held your breath during a depressurization event you could suffer Barotrauma. I think what they are talking about here is just breathing oxygen in an unpressurized airplane.

[jlunseth]

ATC often does not allow flight at FL180.  The reason is that all the IFR aircraft assigned to FL180 have their altimeters set to 29.92, while all the VFR aircraft just below that (say, 17500) have their altimeters set to local pressure, or to a pressure assigned by Flight Following.   On many days this means that the 17,500 aircraft and the FL180 aircraft are at the same absolute altitude.  So when the pressure is wrong, which is often, ATC will not assign FL180.   Your choices would be 16,000 (where you would be on a VFR altimeter setting) or FL200 (where you will be on 29.92).  So one cannot equip one's aircraft on the assumption that you can cruise along at 18k, because you probably can't.  My experience has been that I only get 180 about half the time I ask for it, and on a long cross country of a few hours it is only a matter of time before I am in a different pressure zone and they will tell me I need to either go to 16k or FL200.

 

The Useful Consciousness tables all assume that O2 drops instantly from normal to the pressure for that altitude.  In essence, they assume an explosive decompression or rapid decompression.  In that event there is no opportunity to hold your breath, and as noted you would not want to, the change in pressure would burst your lungs.  The lungs are not able to hold very much pressure without damage. I am going from memory, but I recall that the number is around .5 psi. In water, that is only a couple of feet in depth change.

 

 If a human breathing pressurized air is suddenly subjected to an ambient vacuum, such as would be the case at FL500, a number of uncomfortable things begin to happen rapidly the net effect of which is that blood pressure drops and blood flow to the brain stops very quickly.  Here is an article:  http://www.geoffreylandis.com/vacuum.html

 

At FL250 the most serious of these mechanism would not occur - a pressure suit is not required to fly at 250.  However, if your supplemental O2 ceases to flow it will not take long for brain function to suffer. 

[aviatoreb]

Very interesting!  Thanks - did not know.

 

But if those tables are based on explosive decompression, then another table would be needed for airplanes that were never pressurized in the first place for what loss of consciousness would look like if O2 supply fails.  I would be very surprised if that table does not exist somewhere.