Flatlanders Up At 14,000 - Learned A Lot

Discussion in 'Flight Following' started by Sinistar, Aug 22, 2019.

  1. flyingcheesehead

    flyingcheesehead Touchdown! Greaser!

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

    Ummm... What about the PIC? :goofy:

    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.

    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?
     
  2. PlasticCigar

    PlasticCigar Pre-Flight

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    My first experience at high altitude was actually in a glider when I was 15. We had excellent soaring conditions that day and some mountain wave so my instructor told me “if you start feeling really good, you’re probably hypoxic so you need to come down!”

    SCUBA diving is very different from flying. If you go too deep on air you get nitrogen narcosis from too much absorbed nitrogen (kind of acts like a crappy anesthetic) and if you go too deep with nitrox you can get oxygen toxicity and seizures. These are issues related to TOO MUCH (nitrogen and oxygen respectively).

    Hypoxia is TOO LITTLE oxygen so it’s an entirely different animal. Most people function well at an SpO2 of 92-100%. If you have chronic lung disease you may go as low as 88%, but then you would probably require a SI medical so that’s a different story.

    Once you get below 88% the oxyhemoglobin dissociation curve drops rapidly. People expect a linear drop, but if you look at the curve (just google it) you will see how quickly the SpO2 drops when PaO2 decreases. I believe you encountered this in your experiments.

    I have built-in oxygen and use it anytime I’m above 8000’ or if my SpO2 is <93%. I think any CFI can review this with you. I would also recommend a mountain flying course if you have the time.

    Hope that helps.
     
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  3. woodchucker

    woodchucker Cleared for Takeoff

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    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!
     
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  4. Salty

    Salty En-Route PoA Supporter

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    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.
     
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  5. Dr. O

    Dr. O Pattern Altitude

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    Just a comment. At high DA an engine is way down on power. Power is proportional to RPM. So, why would we pull the prop back? Run it forward to the max continuous and leave it there. We wouldn't try to take off with the prop at the middle of the green arc. Why would we try to climb at altitude with the prop pulled down?
    Actually, for most engines above 10 thousand I would have the prop full forward. The 5 minute (or whatever) time limitation on take off RPM is determined by heat rise not by rpm. That extra hundred or so rpm at that low of a fuel flow (i.e. low heat generation) will not damage the engine if run continuous. But that's just me after a lifetime tinkering with engines. (shrug)
    Now, there might be a propeller vibration or resonance limitation for that last 50 or 100 rpm on a particular engine and that I would heed - but a call to the factory would clarify if that is an issue.
    This question was raised by a Continental engine specialist over 30 years ago when we were discussing performance of my then engine (IO520D / Super Viking) at OSH. His final advice was, let it turn and stop choking it. So, I did on the flight home from OSH at 11K (I don't remember the DA for that run). Fuel flow remained the same. Head temperature went down slightly. I gained 3 knots at the same MP.
     
  6. idahoflier

    idahoflier Line Up and Wait

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    Nothing at all wrong with your plans, just thought I would throw out another option, go a bit north of your proposed route, KSHR --> KGEY --> KCOD and then follow HYW 20 through the Sylvan pass then it's a left turn to KJAC. My daughter and I took this route last year in our Skyhawk on the way home from OSH and the scenery was fantastic. The FBO at SHR was great and they can get you a rate at the Holiday Inn. That far north you can do a Devil's Tower flyby on the way to KSHR...

    3K AGL is probably a bit overkill, especially during mornings, but there is no substitute for being within your comfort zone! Have fun, it's going to be a great trip!
     
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  7. danhagan

    danhagan Pattern Altitude

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    Opening a window helps too:confused::eek:



    Obviously kidding before the fun police show up;)
     
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  8. denverpilot

    denverpilot Tied Down

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    There’s no limit on his engine with the stock prop. Can leave it full forward all day if you like. The green arc on RPM is just a suggestion and matches the performance table in the POH, but it also states max RPM on the climb chart for high altitudes in his aircraft.

    Change the prop, YMMV.

    He should check this against his POH, of course. But all the way up to my P model of his airplane I have never seen an RPM limit other than redline.
     
  9. WannFly

    WannFly En-Route

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    Thanks. We actually plan on coming back that way, but great to hear that you did it in a sky hawk, we will be doing this in a 182 and flying in the morning, till noon.
     
  10. Sinistar

    Sinistar Pattern Altitude

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    Okay round #2 completed!
    TLDR: Went great.

    So the first test resulted in a lot of learning. Last night I went up solo since my wingman was buzzing around at 1000agl over in ND (I'll come back to that). I took the plane up to 14700msl and DA was just under 16000.

    The Climb
    For this climb I started at Vy (90mph) per @flyingcheesehead's recommendation. By 14,000 I had adjusted back to about 84mph which is within 2mph of POH for that altitude.

    Cruise At 14700
    I leveled off and transitioned back to cruise to check ias/tas and get a couple o2 measurements before heading down.

    I was showing TAS=139kts. On my Labor day flight up north I had a 136kts at 7800 and 137kts at 9300. So the 182 is making book numbers in cruise. Ground speed was around 180mph but I purposely had the tailwind for the return.

    Manifold & Mixture
    During the last part of the climb MP was like 7" or 8". I always had full RPM but then again I had it full forward for the climb. The cylinder heads stayed cool. The oil was getting a bit warm but that brings me to mixture.

    The last part of the climb was about 200fpm. But when I brought in the mixture (mainly to cool things down a bit) she also got some power..maybe like another 100fpm. So you guys were right I was too lean.

    I am guessing I could have climbed to 15500 but not sure if any more. I was full fuel 80gal, 02 bottle, cameras, etc.

    Some Weather/Night
    I probably could have continued the climb but there was a black blob of clouds to the nearby west blocking out the sun entirely and it was 20 min to sunset with nearly 3 miles to go down and not kill the ears.

    Communications:
    Now the funny part. I had no clue @WannFly was up flying. When I was at 13000 or so I heard him on 122.8. I made a quick call but no reply. After texting later that night I learned he was up flying. When I heard him he was at 1000agl....and over 200 miles away!

    Cameras:
    Part of the test was gopro stuff. I now have all cameras on battery banks and the smart remote is working well. Having the intercom wire up in the headliner to the main camera is so nice. One gotcha...it really picks up that old flashing beacon which is literally like 5 inches away. The good news is that Adobe Premiere's high pass audio filter seems to completely eradicate it and there's nothing else on the intercom at that low frequency that getting lost. Oh yeah, one suction cup gave up at 13500 and had to be reset.

    Oxygen
    We learned a lot about o2 at altitude on our first flight so the majority of time was spent on o2 delivery options, oximeters, cannula, rates, etc.

    Because the majority of my flights will not need o2 I decided against a pulsed system i figure this trip (if we even make it) is an exception. I can see using it for night flight and maybe longer tailwind flights at 10k...11k.

    O2 Delivery
    So I decided to go DIY. I bought a 411liter medical o2 bottle, 0...10lpm regulator, a medical to aviation/welding adapter and a bag of y's, swivels, etc. Brought it to the FBO and 15 minutes later it was filled.

    I spent a fair amount of time understanding flow rates and cannulas better. So glad I did that and ordered 2 oximizer/oxisaver cannulas. I bought from a medical company so different name but same thing and $10 cheaper each.

    I am probably at $130 for the o2 system and oximeter. With oxisaver cannulas I think it would feed a single adult at 10hrs. I think the whole setup probably weighs 8.5lbs.

    During my flight I never had a reading below 95%. The majority of the flight was with the regulator at 0.5lpm. Once I reached 13k and saw the number come down I switched to 1lpm. However with the oxisaver cannula I think I really needed about 0.6lpm. So a fine flow adjust is needed last.

    Oximeters
    Lots of ways to go here. From the 1st flight I didn't care for the fingernail kind. I found this cool ring style (WearO2) but the display can not be read in any direct light. So I returned all the other stuff and kept a Fitbit knock off that does o2. It seems the most accurate but takes a while to generate a reading. But it leaves both hands open. However with a good o2 supply the o2 monitor doesn't need to be run every 11 seconds.
     
  11. flyingcheesehead

    flyingcheesehead Touchdown! Greaser!

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    Cool! Sounds like you took what you learned the first time, plus our suggestions, and learned more. Good work.
     
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  12. Sinistar

    Sinistar Pattern Altitude

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    Thanks for the help!
     
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  13. Rgbeard

    Rgbeard Cleared for Takeoff

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    I'm glad to hear you've graduated from huffing cans of hiker's oxygen.

    I hope you have a safe flight to Jackson.
     
  14. Mike Blackburn

    Mike Blackburn Pre-Flight

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    Late to the party here.. BUT.. Please, for the love of God can we stop using canned oxygen. This is NOT a solution. Let’s look at the physiology.

    Assuming most of us have reasonably normal lung volumes, the total capacity of the lungs is about 4-5litres.
    Normal breathing (tidal volume) will result in about 1800-2200ml of this capacity NOT being eliminated from the lungs. This means that there is about 400-450ml of oxygen in this volume. After maximal exhalation (think breathing out as far as you can until you basically start coughing), there is STILL some residual volume left - in the region of 1200ml.

    Now, assuming you don’t do this before taking a hit from your oxygen bottle, and you only do a maximal inhalation, you are going to draw in about 3litres of oxygen. Now you have a total of 3500ml of oxygen in your lungs. If you don’t breathe at all (I.e you exhale none of this oxygen), this will last you for about 14minutes (assuming 250ml/min oxygen consumption). Since this is an impossible feat (not breathing for 14min), you’ll almost immediately lose most of the inhaled oxygen on the next time you breathe out, purely because all that gas cannot be absorbed in the time it takes to breathe out.

    Essentially what I’m trying to say is that taking a hit from an oxygen canister will help you increase your oxygen saturation for a matter of a few minutes at the most. They are a gimmick and are of no real use to man or beast. Get a proper oxygen system if you are planning to fly at an altitude which will cause your oxygen saturation to fall below 92-93%. That altitude will vary depending on where you live and your individual physiology.

    It makes not one iota of difference what the FAA says is safe or not safe. Obviously you need oxygen according to the FAA regs, but I think a lot of folks don’t realise that many of us need oxygen at lower levels than the FAA recommended ones. Yes, the initial outlay is expensive, but the stuff is cheap as chips thereafter.
     
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