Flatlanders Up At 14,000 - Learned A Lot

[denverpilot]

Point taken. Just to clarify we spiraled down after hitting 14k, we could never climb any higher and I was running out of math problems to throw at Brad .

“No man, 2 + 2 is 5! What the hell is wrong with you?!”

 

[flyingcheesehead]

Great test and write-up!

The perspective my answers are coming from: I flew a 1971 C182 on an epic Western adventure in 2008, and I've flown the Mooney (M20R, 280hp) to the west coast a couple times as well. I'm based in Wisconsin.

Yesterday I met up with @WannFly and we did a trial run to get more prepared for a potential trip out to Wyoming this coming fall. It was great having another pilot along for this test as the highest I had been before was 11,000 and this upcoming flight might need higher and thus 02 as well. All data is for a 1972 Cessna 182P (stock 230HP).

First off, kudos for doing this test. Way too may pilots bite off more than they can chew with a trip like this. I like to say, you have to push the envelope to become a better pilot - But be sure you only push ONE corner at a time. When I did my first west coast adventure, I did it in an airplane that I had a few hundred hours in and knew really well. I also went with a 2-hour minimum fuel reserve, an oxygen system, and a PLB. (There's a whole lotta nowhere out west - You almost have to fly over it to believe it.) Finally, I stopped at KMYL and took a mountain flying course.

For this one I flew at 85mph which is recommend for best rate of climb above 10,000.

It sounds like you flew 85 from the ground? I wouldn't do that. IIRC, Vx is 63 mph and Vy is 90 mph at sea level? I also thought that they published Vy for every 5000 feet. The service ceiling is supposed to be 18,000 (DA) on the NA 182 and 20,000 on the T182.

From the ground we were climbing around 1000fpm and held 800fpm to about 7,500. Then the climb rate started dropping to around 550fpm and would continue down to about 0fpm at 14,000. We started with manifold pressure of 23" and was at 9" when we leveled off - didn't expect it to be so low. So we stopped there...but for more than one reason.

Interesting. I would have expected better. I made it to 17,500 in the 182 (18K service ceiling) and FL190 in the Mooney (20K service ceiling), both normally aspirated. And the 182 was on a fairly hot day, too... However, I was alone, which helps a lot. (I am 1.6 FAA standard people though. )

This was also the first time I have worked out the engine HP loss based on our altitudes. At 14,000msl we were at DA=15,200ft. The 230HP engine will put out only 125HP at that altitude...wow!!!! In hindsight, its funny to think a fatty Skylane with a fatty pilot can even fly at 125HP.

One of the things I learned at that mountain flying course was how to calculate the climb rate for a given situation before you're in that situation. You start by slowing your plane to Vg but in level flight. Then, convert that power setting to % power and how many horsepower that is. That's the amount of hp you need just to keep the plane in the air, not climbing.

Then, calculate the max HP you can develop at a particular altitude and subtract the keep-the-plane-in-the-air HP to get your excess HP available. Then, the difference goes into this equation:

ft/min climb = Excess HP * 33,000 / [actual gross weight]

So, say it takes exactly 50% hp (115hp) to sustain level flight, and you're going to be flying at an altitude of 16,000 feet. Max HP for a normally aspirated bird up there will be 54% (124.2 hp). Let's say you're at 2700 pounds gross. Your rate of climb would be (124.2-115hp) * 33,000 / 2700 or 112 feet per minute.

This brings up a more general question. If we stick to normally aspirated single engine piston planes and lets go more specific with 180/182/Dakota/Pathfinder/etc or basically all the 230HP or 235HP non-turbo planes. Can any of those go much higher than we did? No matter what they will be like a 125HP plane up there right? So how often are people in those classes of planes flying over 10K mountains at say 13K?

Climb is a function of excess horsepower. That's part of why a 182 will climb better than a 172 - It has at least 50 extra HP, and it's not that much heavier. The 182's power loading is a couple less pounds per hp.

Any normally aspirated plane's available power is going to be about the same percentage at the same altitude. We're all flying in the same atmosphere.

The Mooney does well up high because it has a lot more engine than it needs.

Thanks for offering insight Nate! You live up in the mountains and are in this all the time.

Re:Headache. I figured for sure I would get a headache. But I didn't. I also figured I would be really wiped out but wasn't. But it was very obvious when O2 got low in the lower 80's. Just started feeling tired. @WannFly can tell you if was getting silly!

That's why it's a good idea to do the FAA's altitude chamber course. Every person's symptoms are different, and it's nice to be able to find out what yours are in a safe environment.

I was leaning, not often and probably not aggressively. I sticked the tanks before and after (not accurate) and showed about 10gal used for almost an hour of flight of which 2/3 was the climb and level off. So I definitely wasn't running rich. I have even gotten more comfortable taking off slightly leaned when DA is up a bit so I probably tookoff with the mixture out about 1" and then pulled it back another 1" for the first part of the climb. And maybe another 1/2" for the rest of the climb. With no engine monitor I can only do the stumble and back in approach.

I guess I didn't have the prop all the way in. When I get about 700agl after takeoff I bring it back into the green arch (about 150rpm or so). I left it there for the entire climb.

So maybe a few takeaways is that I could have probably leaned a bit more and I could have brought the prop all the way back in.

You may have leaned too much as well. Hard to say without an engine monitor.

once we saw below 90, we were both taking O2 shots like it was nobody's business

Don't take shots. Use the cannulas.

 

[N1120A]

One thing missing here - did you step climb? That is something that helps massively in my Tiger, which much prefers 4000-8000'. There's no way I could get to the service ceiling of 13,800 straight up - especially at typical California temps. I did get to 10k the other day, relatively effortlessly, by ATC cooperating and giving me time at 7000, a PD climb to 9000 and then finally 10 when the MEA picked up.

 

[Salty]

One thing missing here - did you step climb? That is something that helps massively in my Tiger, which much prefers 4000-8000'. There's no way I could get to the service ceiling of 13,800 straight up - especially at typical California temps. I did get to 10k the other day, relatively effortlessly, by ATC cooperating and giving me time at 7000, a PD climb to 9000 and then finally 10 when the MEA picked up.

Do you have engine cooling issues when climbing at altitude?

 

[N1120A]

Do you have engine cooling issues when climbing at altitude?

Grummans generally have issues with engine cooling and have to be properly managed. That said, it is more an issue of gaining speed to trade for altitude.

 

[Salty]

Grummans generally have issues with engine cooling and have to be properly managed. That said, it is more an issue of gaining speed to trade for altitude.

Vy is Vy. Step climbing will always be slower than climbing at Vy. It’s more gratifying to see the altimeter clicking over in a zoom. But it’s still slower than just sticking to Vy.

 

[N1120A]

Vy is Vy. Step climbing will always be slower than climbing at Vy. It’s more gratifying to see the altimeter clicking over in a zoom. But it’s still slower than just sticking to Vy.

Slower to the final altitude, but not ultimately slower. Vy is the shortest time to a certain altitude, not the shortest time to get somewhere and not necessarily the best way to climb when managing performance.

 

[Salty]

Slower to the final altitude, but not ultimately slower. Vy is the shortest time to a certain altitude, not the shortest time to get somewhere and not necessarily the best way to climb when managing performance.

I know better than to try to argue, but if you intend to climb to altitude x, the fastest way to get to your destination is Vy. Going faster is less efficient. Period.

 

[1RTK1]

Do you have engine cooling issues when climbing at altitude?

I haven’t yet had any problem with engine cooling in my tiger when climbing, usually below 380 any time of the year here in kalifornia.
I usually climb faster than Vy, all the way to cruise alt.

 

[WannFly]

One thing missing here - did you step climb? That is something that helps massively in my Tiger, which much prefers 4000-8000'. There's no way I could get to the service ceiling of 13,800 straight up - especially at typical California temps. I did get to 10k the other day, relatively effortlessly, by ATC cooperating and giving me time at 7000, a PD climb to 9000 and then finally 10 when the MEA picked up.

We didn’t step climb

 

[Salty]

I haven’t yet had any problem with engine cooling in my tiger when climbing, usually below 380 any time of the year here in kalifornia.
I usually climb faster than Vy, all the way to cruise alt.

As do I, but for cooling not out of a misplaced belief that it’s faster.

 

[flyingcheesehead]

I know better than to try to argue, but if you intend to climb to altitude x, the fastest way to get to your destination is Vy. Going faster is less efficient. Period.

To your destination?

I would disagree. I see what you're saying - After all, when you accelerate from Vy you're trading the excess horsepower you were using for climb, and instead using it to accelerate and counteract the ever-increasing parasitic drag.

However, when you're approaching the ceiling of the aircraft and the climb rate becomes close to zero (as happened to me the other day trying to climb the TBM to FL310 with the inertial separator on...), you'll most certainly get to your destination faster if you stop your climb earlier and step climb. Why? Because when you step climb, you're not only making more progress toward your destination, you're also lowering the weight of the aircraft as you're burning fuel.

So, in the case of the TBM, when we turned the separator on we needed to drop from 75% torque to 50% torque (we're temp-limited at those altitudes, especially with the separator on). That's a loss of about 212hp, which obviously kills your climb rate. We basically got stuck at FL305 - No climb, no acceleration.

Were that a valid altitude, we could have stayed there all day long at max power (for the conditions) and been flying 135 KIAS/230 KTAS. Instead, we dropped back down to FL290 where we had some excess power, and gained about 30 knots of true airspeed.

Now, what ended up happening is that we spent several minutes there, got out of the muck, turned the separator off, got our power back, and climbed the last 2000 feet in a bit over a minute. But if we had needed to leave the separator on, an hour later we would have been 400 pounds lighter and we would have been able to climb the rest of the way in a reasonable amount of time, make it to 310, and accelerate again to a somewhat-reduced cruise speed rather than being stuck at Vy for the rest of the flight.

 

[Salty]

To your destination?

I would disagree. I see what you're saying - After all, when you accelerate from Vy you're trading the excess horsepower you were using for climb, and instead using it to accelerate and counteract the ever-increasing parasitic drag.

However, when you're approaching the ceiling of the aircraft and the climb rate becomes close to zero (as happened to me the other day trying to climb the TBM to FL310 with the inertial separator on...), you'll most certainly get to your destination faster if you stop your climb earlier and step climb. Why? Because when you step climb, you're not only making more progress toward your destination, you're also lowering the weight of the aircraft as you're burning fuel.

So, in the case of the TBM, when we turned the separator on we needed to drop from 75% torque to 50% torque (we're temp-limited at those altitudes, especially with the separator on). That's a loss of about 212hp, which obviously kills your climb rate. We basically got stuck at FL305 - No climb, no acceleration.

Were that a valid altitude, we could have stayed there all day long at max power (for the conditions) and been flying 135 KIAS/230 KTAS. Instead, we dropped back down to FL290 where we had some excess power, and gained about 30 knots of true airspeed.

Now, what ended up happening is that we spent several minutes there, got out of the muck, turned the separator off, got our power back, and climbed the last 2000 feet in a bit over a minute. But if we had needed to leave the separator on, an hour later we would have been 400 pounds lighter and we would have been able to climb the rest of the way in a reasonable amount of time, make it to 310, and accelerate again to a somewhat-reduced cruise speed rather than being stuck at Vy for the rest of the flight.

I don't really follow the internal separator part of your discussion, but barring cooling issues, or other mechanical reasons to adjust, Vy is Vy is Vy. Stopping your climb to speed up and then zoom climb is going to result in a longer climb to altitude than if you just flew Vy. Parasitic drag goes up exponentially with speed.

 

[denverpilot]

We basically got stuck at FL305...

We’re all going to bust out the world’s smallest violins for you. Hahaha.

 

[deyoung]

This brings up a more general question. If we stick to normally aspirated single engine piston planes and lets go more specific with 180/182/Dakota/Pathfinder/etc or basically all the 230HP or 235HP non-turbo planes. Can any of those go much higher than we did?

I've had my Cherokee-235 up to 12,500, but as mentioned it takes awhile. I believe its published service ceiling is 12,000 and absolute ceiling is 13,900. It's not unusual that I'll take it up to 8000 or 9000-ish, especially if that helps find smoother air in the summer, but it's usually not worth it to get above that.

I prefer not to spend a huge amount of time over sharp pointy things anyway, even if I have the altitude to clear them. Going from Tucson to Colorado Springs, for example, I'll fly more or less to Deming and then follow the Rio Grande north rather than go direct over the White Mountains, even though I could clear them.

 

[Sinistar]

Real deep slow breaths in and out bring my O2 levels back up at high density altitudes without supplemental oxygen.

I am aware of this. However it is my understanding that although this breathing technique can bring up the 02 levels that you read (ie oximeter) it does not necessarily restore oxygen levels where they are needed (tissue). I think it bonds to the hemoglobin vs getting released back into the tissue where it is needed. So for this albeit short test I didn't want to only rely only on a breathing technique. If my understanding of the slow deep breaths vs getting O2 restored properly is wrong I hope someone will chime in right away.

 

[Sinistar]

Remember that temps drop when you get higher. Year ago,June, I went from Denver to Alamosa by way of PUB then Mosca Pass. Took the pass at 13.5 altho I planned for 12.5. But the cherokee just kept climbing. I wasn’t expecting the cold, so I threw the flight bag down on the pax floor to block the cold air coming in the floor vents. At this timestamp, noon Aug 23, Monarch Pass is 53 deg at physical alt of 12k.

What was weird for us is that for about 5000ft of the climb (6000msl to 11000msl) the temperature was constant. I figured it would drop at least 2F per 1000ft and that would have been in favor w/r to DA.

 

[Sinistar]

As @WannFly stated we did not step climb. Just 85mph the entire climb. I know I could have climbed faster (eg 70mph) early in the climb but I wasn't in a big hurry and the constant speed made the climb effect vs DA altitude a bit more obvious.

Also I wasn't sure about engine cooling as I had never done this long (time) of a climb before so I figured better to play it on the safe side and get a little more air into the cowls and out the cowl flaps.

There was never a engine overheating problem. As far as I recall the cylinder head temp (old Cessna single gauge) was at about 1/2 or slightly less (in the green) the entire climb.

 

[Sinistar]

Great test and write-up!

The perspective my answers are coming from: I flew a 1971 C182 on an epic Western adventure in 2008, and I've flown the Mooney (M20R, 280hp) to the west coast a couple times as well. I'm based in Wisconsin.



First off, kudos for doing this test. Way too may pilots bite off more than they can chew with a trip like this. I like to say, you have to push the envelope to become a better pilot - But be sure you only push ONE corner at a time. When I did my first west coast adventure, I did it in an airplane that I had a few hundred hours in and knew really well. I also went with a 2-hour minimum fuel reserve, an oxygen system, and a PLB. (There's a whole lotta nowhere out west - You almost have to fly over it to believe it.) Finally, I stopped at KMYL and took a mountain flying course.



It sounds like you flew 85 from the ground? I wouldn't do that. IIRC, Vx is 63 mph and Vy is 90 mph at sea level? I also thought that they published Vy for every 5000 feet. The service ceiling is supposed to be 18,000 (DA) on the NA 182 and 20,000 on the T182.



Interesting. I would have expected better. I made it to 17,500 in the 182 (18K service ceiling) and FL190 in the Mooney (20K service ceiling), both normally aspirated. And the 182 was on a fairly hot day, too... However, I was alone, which helps a lot. (I am 1.6 FAA standard people though. )



One of the things I learned at that mountain flying course was how to calculate the climb rate for a given situation before you're in that situation. You start by slowing your plane to Vg but in level flight. Then, convert that power setting to % power and how many horsepower that is. That's the amount of hp you need just to keep the plane in the air, not climbing.

Then, calculate the max HP you can develop at a particular altitude and subtract the keep-the-plane-in-the-air HP to get your excess HP available. Then, the difference goes into this equation:

ft/min climb = Excess HP * 33,000 / [actual gross weight]

So, say it takes exactly 50% hp (115hp) to sustain level flight, and you're going to be flying at an altitude of 16,000 feet. Max HP for a normally aspirated bird up there will be 54% (124.2 hp). Let's say you're at 2700 pounds gross. Your rate of climb would be (124.2-115hp) * 33,000 / 2700 or 112 feet per minute.



Climb is a function of excess horsepower. That's part of why a 182 will climb better than a 172 - It has at least 50 extra HP, and it's not that much heavier. The 182's power loading is a couple less pounds per hp.

Any normally aspirated plane's available power is going to be about the same percentage at the same altitude. We're all flying in the same atmosphere.

The Mooney does well up high because it has a lot more engine than it needs.



That's why it's a good idea to do the FAA's altitude chamber course. Every person's symptoms are different, and it's nice to be able to find out what yours are in a safe environment.



You may have leaned too much as well. Hard to say without an engine monitor.



Don't take shots. Use the cannulas.

Awesome response!!!

Yeah, I would have thought we would have made it another 1000ft at least. The DA was 15,200ft so in theory we should have had more to go. Still pondering that one since we weren't MTOW.

I am starting to wonder if I leaned a bit too much. Its like which is better. The 182s are already run pretty rich but this was new territory for me to figure out.

Yeah, when talking with @WannFly we just figured why not do a trial run right here in the good old flat lands. No big things to "HAVE" to go over. Plenty of time to practice. For example part of the test was a few turns to see how climb rate was effected (not bad some effect). We also had a 45kt wind aloft once we got up over 10,000 so that was interesting to see the ground speeds against the wind vs with the wind. And I climbed at 85mph partly because the 182 is still pretty darn responsive (even clean) so it wasn't like a slow flight practice the entire way up LOL!

Both @WannFly and I are already figuring out 02 systems. I'm gonna go home brew but I am pretty comfortable with HP stuff, O2, regulators, etc. Partly from Navy days and partly from being scuba diver. So no more cans for us.

The funny part about the cans was that we each had 11liters. Plus one other can. We didn't expect to be a 14K very long. But it was what we used on that slow climb up that probably had us most worried because at 14K the rate wasn't getting any less! I had figured we'd need around 0.5lpm starting around 12k and need about 1lpm at 14k. But we were probably needing close to 1.0lpm right around 12K and going up from there. At the hangar yesterday I was taking shots off of my can to see if it was almost out and I still haven't exhausted it but I can tell the flow rate is now not quite as strong. So I'll guess 2 liters left in that one.

My wife has been thru the FAA altitude chamber course. Its funny, her reaction was different than mine. That just means she's normal LOL!

 

[Sinistar]

Problem with the O2 being supplied by cans instead of a bottle connected to a cannula is if something goes wrong in the plane or your bottle gets lost under the seat right when you're already being effected by hypoxia you could become distracted correcting the plane problem. As you've learned, your saturation level drops quickly at those altitudes.

I think that was more and more on our mind as we started going to cans more than we expected. We are already getting a 02 system figured out and will have at least 400liters onboard for the flight along with adjustable inline verifiable flowmeter, oximizer cannula and individual oximeters. Not much of our flight will be a levels needing O2 so this will be more than enough to get out there and its a simple refill before heading back. Next test flight will be using the O2 system so there are no surprises there!

 

[Sinistar]

How does an “oxygen can” satisfy the FAA requirements for supplemental oxygen? Have you considered talking to a CFI before embarking on “Adventures With Hypoxia?” Your write up seems to imply that you are unfamiliar with human physiology and the proper use of aviation oxygen. Might be a good idea to brush up on those before you get hurt.

First off, you could be correct. Perhaps the oxygen can does not satisfy FAA requirements? I will look into it. However we will have a continuous O2 supply onboard for the flight and any future flights.

I would say I had studied as much as I could. I knew what to look for and had a general idea of the flow rates we might need. Ironically, my first symptoms were not standard. I didn't get goofy but rather started to notice being a bit tired. I also had a safety pilot along and ready to help if needed. I have certain training in the Navy and from scuba diving which I think also gave me better insight on what would go on physiologically. Although management and symptoms of PPO2 w/r to nitrox diving are not the same where there you are much more concerned about too much O2.

@PlasticCigar: I would like to ask you this. It is one thing to recommend an instructor. However, in your case perhaps you wouldn't mind sharing your first experience at high altitude in GA. Did you have an instructor along? What did they have you do? How high did you go? Was it a rented plane with O2 or perhaps your own plane? Or perhaps you learned once you got into a professional aviation career or military. In other words. Please also share what you have learned. It is so easy on here to say "Find an instructor". But it can also be quite helpful if you also share your 1st experiences and what you ran into and how you solved them.

 

[Sinistar]

Point taken. Just to clarify we spiraled down after hitting 14k, we could never climb any higher and I was running out of math problems to throw at Brad .

Actually, according to FlightAware and the GP log data I think we actually topped out at like 13,890 or something like that. So technically the 14K portion of the FAR's wouldn't apply to this flight.

 

[Sinistar]

Okay here are some number to compare against the FAR's.

We spent a total of 21 minutes from climbing thru 10,000msl (going up) then level off and then descending (going down) thru (10,000msl). The highest point reached was 13,900 so we never exceeded 14K. Since it was a GA flight there was no required flight crew. I did have a passenger. So now it has me wondering (seriously) which FAR was not complied with. The O2 cans are storage devices. They can deliver O2. It has a mask. It can deliver with positive pressure. Maybe this is just a gray area. Maybe its it fails to comply because there is no indicator for how much is remaining.

 

[RyanB]

Since it was a GA flight there was no required flight crew.

Sure about that?

A flight crew member means a pilot, flight engineer, or flight navigator assigned to duty in an aircraft during flight time - that applies to you.

So now it has me wondering (seriously) which FAR was not complied with.

91.211 Supplemental oxygen.
(a) General. No person may operate a civil aircraft of U.S. registry—

1) At cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen for that part of the flight at those altitudes that is of more than 30 minutes duration;

(2) At cabin pressure altitudes above 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen during the entire flight time at those altitudes.
​

I’m not seeing how this reg could be misconstrued - it’s pretty clear. How long were you between 12,500’ and 14,000’. There’s your answer.

 

[Rgbeard]

Sinistar, Your threads are always fun to read.

Kinda reminds me of the demotivators from fifteen years ago.

 

[Sinistar]

Sure about that?

A flight crew member means a pilot, flight engineer, or flight navigator assigned to duty in an aircraft during flight time - that applies to you.


91.211 Supplemental oxygen.
(a) General. No person may operate a civil aircraft of U.S. registry—

1) At cabin pressure altitudes above 12,500 feet (MSL) up to and including 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen for that part of the flight at those altitudes that is of more than 30 minutes duration;

(2) At cabin pressure altitudes above 14,000 feet (MSL) unless the required minimum flight crew is provided with and uses supplemental oxygen during the entire flight time at those altitudes.
​

I’m not seeing how this reg could be misconstrued - it’s pretty clear. How long were you between 12,500’ and 14,000’. There’s your answer.

in the post you quoted I said the total time from 10K going up to 10K down was 21 minutes. So that includes the 12.5k to 14k part as well. I dont have the 12.5k...13.9k...12.k times...but it is less than 21 minutes. And peak altitude was 13,900. Am I missing something other than the flight crew member part?

 

[RyanB]

in the post you quoted I said the total time from 10K going up to 10K down was 21 minutes. So that includes the 12.5k to 14k part as well. I dont have the 12.5k...13.9k...12.k times...but it is less than 21 minutes. And peak altitude was 13,900.

Sounds like you answered your own question then -you didn’t need it.

Am I missing something other than the flight crew member part?

I’m not sure. You said that because it was a GA flight, that the crew member requirements wouldn’t apply, which is simply incorrect.

If you’re acting as PIC and you have a few passengers in the back, are you not a required crew member? The airplane can’t fly itself, so you would be the required soul on board to operate the airplane. As such, you would need to apply supplemental oxygen as outlined in the regs, the pax would not, because they are not required crew.

 

[WannFly]

View attachment 77178 Sinistar, Your threads are always fun to read.

Kinda reminds me of the demotivators from fifteen years ago.

Pls enlighten

 

[Rgbeard]

Pls enlighten

Why?

 

[WannFly]

Why?

Because I didn’t understand, or you can keep zero value posts and increase your post count. Your call dude

 

[Rgbeard]

I don't understand the value of what you (plural) are doing.

You're simply re-creating experiments that the FAA has done long before you were born, (most probably), when they determined that flights at higher altitudes required supplemental oxygen. You have the value of an experimental physicist at a university re-creating some of Marie Curie 1898 radiation experiments. Ummmmmmm..... can't we accept that which has been determined long before airplane keys found our hands and move forward rather than back?

You're doing it with an amateur-hack flair (huffing from oxygen cans), and documenting your findings with a "Wowwee, lookie what we learned" kind of view of the world.

When I began flying at the oxygen levels, I simply knew to make sure the Scott tanks were full, I knew which cannula was mine, and made sure to put it on at 12,000 feet.

• I didn't have anyone to post to about the experience.
• Didn't play around with huffing from hiker's oxygen cans.
• It wasn't really anything to talk about, or hangar-fly about.
• The rules weren't unnecessarily hard (for me) to understand.
• Seemed pretty clear.
• I started using the approved oxygen when I should and all was well.

If you all can talk on and on and on, overanalyzing this, it simply means you're up for talk about nothing. It's amusing.

I look forward to your next batch of experiments to determine if FAA regulations are really warranted or not.

Carry on, bravely.

 

[WannFly]

I don't understand the value of what you (plural) are doing.

You're simply re-creating experiments that the FAA has done long before you were born, (most probably), when they determined that flights at higher altitudes required supplemental oxygen. You have the value of an experimental physicist at a university re-creating some of Marie Curie 1898 radiation experiments. Ummmmmmm..... can't we accept that which has been determined long before airplane keys found our hands and move forward rather than back?

You're doing it with an amateur-hack flair (huffing from oxygen cans), and documenting your findings with a "Wowwee, lookie what we learned" kind of view of the world.

When I began flying at the oxygen levels, I simply knew to make sure the Scott tanks were full, I knew which cannula was mine, and made sure to put it on at 12,000 feet.

• I didn't have anyone to post to about the experience.
• Didn't play around with huffing from hiker's oxygen cans.
• It wasn't really anything to talk about, or hangar-fly about.
• The rules weren't unnecessarily hard (for me) to understand.
• Seemed pretty clear.
• I started using the approved oxygen when I should and all was well.

If you all can talk on and on and on, overanalyzing this, it simply means you're up for talk about nothing. It's amusing.

I look forward to your next batch of experiments to determine if FAA regulations are really warranted or not.

Carry on, bravely.

first, you probably didnt read the thread or didnt comprehend it. no one said FAA regulations are warranted or not, we know the regulations and as per the regulations we didnt even NEED O2 since we stated less than 20 mins, i have done the same thing with a CFI when i started, without O2, it is perfectly legal. is it smart? probably not, and thats what we wanted to know - what reactions our body will have and at what point we will need O2.

this forum and any other forum is about documenting experience and thats what we are doing, if you dont like it fine, your call, but not sure why you are reading or commenting on posts that you think are just waste of time?

we are flatlanders and like most flatlanders or typical flight levels are between 6-8, we wanted to try this out in our own territories and not learn the hard way over pointy things, you can call it experiment, i call it calculated risk in a controlled environment - there is a difference.

i will be posting a lot more experiences on this board and may be some one will learn from it like i did when i started and still do. feel free to ignore and move on. thats what internet and mostly life is all about.

 

[Rgbeard]

I read your stuff because you're entertaining to me.

That's all.

 

[WannFly]

I read your stuff because you're entertaining to me.

That's all.

good at least one of us is adding some value to the other one.

 

[RyanB]

 

[flyingcheesehead]

I don't really follow the internal separator part of your discussion, but barring cooling issues, or other mechanical reasons to adjust, Vy is Vy is Vy. Stopping your climb to speed up and then zoom climb is going to result in a longer climb to altitude than if you just flew Vy. Parasitic drag goes up exponentially with speed.

OK, I'll do a slightly more hypothetical example with a piston airplane.

My Mooney's service ceiling is 20,000 feet (FL200). But, let's say it's a hot day and that's close to my absolute ceiling at max gross weight.

In a Vy climb, I'll hit 10,000 feet in about 10 minutes and 20 miles. Getting to 15,000 feet will take about another 10 minutes, and about another 25 miles. My next 10 minutes won't quite get me to 18,000 and will eat up another 26 miles. The next 10 minutes might only get me to 19,000 feet and eat up 27 miles. Then, it would probably take 20 additional minutes to get to 20,000 feet, in which I would eat up 54 miles. So, I hit my TOC after a full hour and 152 miles, so an average of 152 knots. But now I'm near my absolute ceiling, and acceleration will be almost nonexistent because I'm using all of my engine power just to maintain altitude at Vy. It might take me another hour to accelerate to something resembling normal cruise, since I have so little excess power available.

Meanwhile, if I stopped the climb at 15,000 feet after 20 minutes and accelerated to normal cruise speed for the next hour and 40 minutes before climbing the last 5,000 feet, the climb would happen much faster than it would have earlier in the flight because the plane is lighter after burning that fuel off, and in the meantime I've covered a lot more ground.

We're in violent agreement that *most* of the time, step climbs don't gain you anything. However, when you're in that last 25% or so of the sky before you reach the airplane's ceiling, it's not necessarily true any more - That's all I'm saying.

We’re all going to bust out the world’s smallest violins for you. Hahaha.

Yep, it's all relative. But in comparison to our usual 300+ knots, it kinda sucks when you run into clouds up high and have to turn the separator on - A bunch of your torque goes away because of the less-efficient airflow, and then you have to pull the power lever back too because the engine starts heating up for the same reason. You lose about 25% of your torque and about 55 knots of airspeed.

 

[flyingcheesehead]

As @WannFly stated we did not step climb. Just 85mph the entire climb. I know I could have climbed faster (eg 70mph) early in the climb but I wasn't in a big hurry and the constant speed made the climb effect vs DA altitude a bit more obvious.

You wouldn't climb faster at 70. Vx is 63 and Vy is 90, right? (It was on ours, 1 year older than yours.) Vy is the best rate of climb. Vx will give you a better *angle* but a worse *rate*. So, if you want to get to 14,000 as fast as possible, you want Vy.

Now, both Vx and Vy change with altitude, and at the airplane's absolute ceiling they will be equal. Unfortunately I only have a 182Q POH handy at the moment, but it says:

Vx at sea level: 54 KIAS (62 mph)
Vx at 10,000: 62 KIAS (71 mph)
Vy at sea level: 78 KIAS (90 mph)
Vy at 10,000: 72 KIAS (83 mph)

IIRC the change is linear, so at 20,000 Vx would be 70 KIAS/80mph and Vy would be 66 KIAS/76 mph. Since they've crossed, well, the ceiling is clearly below 20,000 feet.

But, what you want to do is start your climb at 90 mph, and bring it slowly back so that you're at maybe 87 mph by 5,000, 83 mph by 10,000, and 80 mph by 15,000. You don't want to start at 80 all the way down on the ground unless you're taking off at Leadville.

Awesome response!!!

Glad to help.

Yeah, I would have thought we would have made it another 1000ft at least. The DA was 15,200ft so in theory we should have had more to go. Still pondering that one since we weren't MTOW.

Hmm. The only thing I can come up with is that either there's some sort of aerodynamic issue that's causing a lot of extra drag, or you were pretty far from the optimum mixture. What speeds do you normally see in cruise?

I am starting to wonder if I leaned a bit too much. Its like which is better. The 182s are already run pretty rich but this was new territory for me to figure out.

I would say that you probably want to err on the side of too rich. Best power mixture is usually around 125ºF rich of peak, and even the big-name LOP proponents (Deakin et al) recommend climbing rich of peak because if you get distracted by something (or hypoxic) during the climb your engine will be trending cooler as you climb, not hotter.

Having an engine monitor, or at the very least an EGT gauge, is necessary to lean accurately enough to get a reasonable climb. Our EGT gauge in the Mooney actually has a green range marked "climb" which makes it really easy! And you'd be surprised how significant the difference in performance is when you've been neglecting the mixture while you attend to other duties and then you fix it. Is there any chance you could/would install one before your trip?

 

[flyingcheesehead]

Okay here are some number to compare against the FAR's.

We spent a total of 21 minutes from climbing thru 10,000msl (going up) then level off and then descending (going down) thru (10,000msl). The highest point reached was 13,900 so we never exceeded 14K.

So it was less than 21 minutes above 12,500.

Since it was a GA flight there was no required flight crew.

Ummm... What about the PIC?

I did have a passenger. So now it has me wondering (seriously) which FAR was not complied with. The O2 cans are storage devices. They can deliver O2. It has a mask. It can deliver with positive pressure. Maybe this is just a gray area. Maybe its it fails to comply because there is no indicator for how much is remaining.

There were no FARs that weren't complied with (at least regarding oxygen). The cans are irrelevant. Legally, you didn't need any O2 at all.

I don't understand the value of what you (plural) are doing.

You're simply re-creating experiments that the FAA has done long before you were born, (most probably), when they determined that flights at higher altitudes required supplemental oxygen. You have the value of an experimental physicist at a university re-creating some of Marie Curie 1898 radiation experiments. Ummmmmmm..... can't we accept that which has been determined long before airplane keys found our hands and move forward rather than back?

They're seeing how both they and their aircraft perform at high altitudes in preparation for a trip where they're going to need to be at high altitudes. They're preparing and they're learning. If only all pilots would do such things, we would have much fewer accidents. And by posting about it here, we can offer suggestions based on our experiences that will make their next flight safer and easier.

This is the highest calling of hangar talk. If you feel the need to poo-poo it, why don't you just take your ball and go home?

 

[woodchucker]

Careful on maintaining cooling. Our club 182 has a suggested climb speed of 100 kts in the summer heat and that is from 4000+ feet base of operations. Don’t over lean, keep the cht below 400.

Regarding O2 I never carry it. Max cruise for me is typically 11.5. I have been caught in an up-air cycle to 15+ once in a 172. That was interesting. As the altimeter upwound I found myself thinking about what exactly happens when the airplane decides to quit flying. Thankfully I was released and was able to coast back down.

Hopefully catch you up in Driggs or wherever you decide on!

 

[Salty]

OK, I'll do a slightly more hypothetical example with a piston airplane.

My Mooney's service ceiling is 20,000 feet (FL200). But, let's say it's a hot day and that's close to my absolute ceiling at max gross weight.

In a Vy climb, I'll hit 10,000 feet in about 10 minutes and 20 miles. Getting to 15,000 feet will take about another 10 minutes, and about another 25 miles. My next 10 minutes won't quite get me to 18,000 and will eat up another 26 miles. The next 10 minutes might only get me to 19,000 feet and eat up 27 miles. Then, it would probably take 20 additional minutes to get to 20,000 feet, in which I would eat up 54 miles. So, I hit my TOC after a full hour and 152 miles, so an average of 152 knots. But now I'm near my absolute ceiling, and acceleration will be almost nonexistent because I'm using all of my engine power just to maintain altitude at Vy. It might take me another hour to accelerate to something resembling normal cruise, since I have so little excess power available.

Meanwhile, if I stopped the climb at 15,000 feet after 20 minutes and accelerated to normal cruise speed for the next hour and 40 minutes before climbing the last 5,000 feet, the climb would happen much faster than it would have earlier in the flight because the plane is lighter after burning that fuel off, and in the meantime I've covered a lot more ground.

We're in violent agreement that *most* of the time, step climbs don't gain you anything. However, when you're in that last 25% or so of the sky before you reach the airplane's ceiling, it's not necessarily true any more - That's all I'm saying.



Yep, it's all relative. But in comparison to our usual 300+ knots, it kinda sucks when you run into clouds up high and have to turn the separator on - A bunch of your torque goes away because of the less-efficient airflow, and then you have to pull the power lever back too because the engine starts heating up for the same reason. You lose about 25% of your torque and about 55 knots of airspeed.

Ok, I’m with you. Not sure why you’d climb that high in a naturally aspirated aircraft, but I’m with you. Honestly my C model climbs so slow at 12,000 I can’t imagine going to 19.