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Ceiling

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kaweeka

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Since I didn't build my -9A and do the performance flights, I always wanted to know my ceiling. Living in the Sacramento Valley, it's nice to know how high I can go to get over the mountains with room to spare. Today was a great day to do this. I took off from KLHM and called up NorCal approach, asking if they had time to help me with my quest. They gave me an area between Beale AFB and Grass Valley, initially cleared to 19,000. That came and went with requests every thousand feet untilI stopped at 24,000. My oxygen just couldn't keep up through a nasal cannula with SpO2 drifting down to 80%. That was enough for me to head down. The controller was great. I told him the book says 19,000 for a ceiling and after passing 21,000 he suggested we "go for the record". FYI, the data at 24,000 from my G3x showed 11.0" Hg, 38% hp. It's on Flightaware. I might have been able to get to 25,000 but just didn't feel comfortable with O2 trending down. Maybe I'll get a mask from my office and try it again.
Happy 4th everyone

David
 
Since I didn't build my -9A and do the performance flights, I always wanted to know my ceiling. Living in the Sacramento Valley, it's nice to know how high I can go to get over the mountains with room to spare. Today was a great day to do this. I took off from KLHM and called up NorCal approach, asking if they had time to help me with my quest. They gave me an area between Beale AFB and Grass Valley, initially cleared to 19,000. That came and went with requests every thousand feet untilI stopped at 24,000. My oxygen just couldn't keep up through a nasal cannula with SpO2 drifting down to 80%. That was enough for me to head down. The controller was great. I told him the book says 19,000 for a ceiling and after passing 21,000 he suggested we "go for the record". FYI, the data at 24,000 from my G3x showed 11.0" Hg, 38% hp. It's on Flightaware. I might have been able to get to 25,000 but just didn't feel comfortable with O2 trending down. Maybe I'll get a mask from my office and try it again.
Happy 4th everyone

David

I suggest downloading and sending the data to Savvy to get analyzed and maybe even get tips on how to make the engine perform even better for your next attempt.
 
Were you level long enough anywhere to allow the airplane to accelerate and note your TAS?
 
What was the rate of climb as you approached FL240?
Using a cannula above 18,000? is against the rules, but I am surprised your blood-Ox dropped so low. Do you recall the flow rate you were using on the O2?
 
What was the rate of climb as you approached FL240?
Using a cannula above 18,000? is against the rules, but I am surprised your blood-Ox dropped so low. Do you recall the flow rate you were using on the O2?

Climb rate was between 100-200 fpm. You all are right, I should have remembered the requirement for the mask.
 
I think the ?book? values are extrapolated from test data for what the ceiling would be at gross weight. Anything lighter would allow higher.
 
What was the rate of climb as you approached FL240?
Using a cannula above 18,000? is against the rules, but I am surprised your blood-Ox dropped so low. Do you recall the flow rate you were using on the O2?

I didn?t realize there were rules restricting cannula use above fl180, so I looked it up. Although oxygen deprivation is pretty serious, and I applaud the OP for monitoring his levels, does FAR 23.1447 not actually apply to experimental aircraft that aren?t certified under part 23? I would think that he didn?t break any rules unless perhaps his ops limitations have a ceiling, and he should have gone back to phase 1 to expand them, but I don?t really know. Anybody care to chime in?
 
I didn?t realize there were rules restricting cannula use above fl180, so I looked it up. Although oxygen deprivation is pretty serious, and I applaud the OP for monitoring his levels, does FAR 23.1447 not actually apply to experimental aircraft that aren?t certified under part 23? I would think that he didn?t break any rules unless perhaps his ops limitations have a ceiling, and he should have gone back to phase 1 to expand them, but I don?t really know. Anybody care to chime in?

FAR 23.1447 probably is not the controlling regulation in this case (although I tend to agree, it does not apply, for a few reasons...)

The cannula itself is only approved for use up to 18,000'. Probably if you look around the documentation for the unit in question, it has a statement saying just that. The fact that the cannula is being used in an experimental aircraft most likely does not factor into the equation in this case.
 
FAR 23.1447 probably is not the controlling regulation in this case (although I tend to agree, it does not apply, for a few reasons...)

The cannula itself is only approved for use up to 18,000'. Probably if you look around the documentation for the unit in question, it has a statement saying just that. The fact that the cannula is being used in an experimental aircraft most likely does not factor into the equation in this case.

I don?t think a manufacturer can make a statement ?approving? or ?not approving? a product for use in an experimental. I?m sure Chevy or Subaru doesn?t ?approve? their products for aircraft. Maybe I?m wrong here, but if you comply with applicable sections of part 91, I think you?re good, no?
 
I don’t think a manufacturer can make a statement “approving” or “not approving” a product for use in an experimental. I’m sure Chevy or Subaru doesn’t “approve” their products for aircraft. Maybe I’m wrong here, but if you comply with applicable sections of part 91, I think you’re good, no?

Discussing cannulas, in the FAA Document titled Oxygen Equipment Use in General Aviation Operations

"They are restricted by federal aviation regulations to 18,000 feet service altitude because of the risk of reducing oxygen-blood saturation levels
if one breathes through the mouth or talks too much."

I am not sure if the regulation mentioned above is FAR 23.1447 or not.
 
That came and went with requests every thousand feet untilI stopped at 24,000. My oxygen just couldn't keep up through a nasal cannula with SpO2 drifting down to 80%.

David

You might have been a bit lucky on that flight. I?m guessing that an SpO2 reading of 80% might have put you on the threshold of serious mental impairment. Hypoxia at altitude is very insidious...the worse it becomes the less you comprehend that you are suffering from it.
 
You might have been a bit lucky on that flight. I?m guessing that an SpO2 reading of 80% might have put you on the threshold of serious mental impairment. Hypoxia at altitude is very insidious...the worse it becomes the less you comprehend that you are suffering from it.

?A bit lucky? is a bit exaggerated. SpO2 of 80% is what you would expect at 15,000 ft without supplemental O2. The FAA allows us to bring passengers to 15k without O2. Skydivers routinely go to 15K without O2. I am not saying that mild hypoxia is not present at 80% but we need to be reasonable.

On another note to the OP all I can say is very cool! Thanks for posting.
 
?A bit lucky? is a bit exaggerated. SpO2 of 80% is what you would expect at 15,000 ft without supplemental O2. The FAA allows us to bring passengers to 15k without O2. Skydivers routinely go to 15K without O2. I am not saying that mild hypoxia is not present at 80% but we need to be reasonable.

The OP is not a passenger....he?s the sole pilot...big difference.

The FAA requires supplemental oxygen for pilots when flying above 12,500? for more than 30 minutes. 12,500? is equivalent to an Sp02 of 87%. The FAA further requires supplemental oxygen for pilots at any time above 14,000?. 14,000? is equivalent to an SpO2 of 83%.

An SpO2 of 80% is equivalent to 15,250? without supplemental oxygen and is regarded as the threshold of moderate hypoxia. Moderate hypoxia is where you start experiencing mental impairment. The extent of that impairment will vary between individuals depending on age and physical condition.

Incidentally the FAA requirement for supplemental oxygen over 12500? is actually quite generous...other aviation authorities feel that?s too liberal. In Australia for example CASA requires supplemental oxygen for a pilot over 10,000? in an unpressurised aircraft for any period of time.

The FAA also mandates a maximum altitude of 18,000? for nasal cannula oxygen supply...and there?s good reason for that. In this case the OP was up at 24,000?, well above the maximum. I?m thinking that this is not a practice that other pilots on VansAirforce should attempt to emulate.
 
Other points to consider- in my part of the DoD, if we dropped folks above 18000' we had to prebreath 100% O2 on a MASK, monitored by an extra technician.

If we flew unpressurized, max was FL250 unless waived.

Younger, better shape, got a chamber ride every 5 years. You have been to a chamber or simulator for hypoxia training, right?

Ask the glider guys if they go above 180 without a mask.

Just in case any of that is news, it's just some data on getting trained, paid and trusted to stay safe. Part 121 airline, we'd be on masks.

Wish someone would have asked if you were pressurized because talking into a mask sounds different than on a cannula. Most oxymiters have a 4% accuracy window.
 
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Thanks for posting David. Sam has a write up by Terry Jantz on his website about taking his RV6 to 26000 ft. With the RV 9 wing optimized for high altitude flight I wonder what you could really do if you took the same preparations. It wouldn’t be apples to apples unless flight conditions could be duplicated but it sure would be interesting. I wonder how much the horsepower affects the trial and if the wing can overcome the lower horsepower.

http://home.hiwaay.net/~sbuc/journal/high.html
 
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Man, I'm tempted to go play with it....

I have had mine to FL190 a few times and once to FL210 just to see if it would get there - it did, but it's not a place I would normally cruise - the performance drops off too quick above 17,000'. Anything above that altitude is just for bragging rights or to clear a bit of weather.

But as just a "gee-whiz, let's go see" kind of flight, I'm real tempted. I think I'll wait until fall or winter and give it a shot. My airspace out here in west Texas is open enough that I don't think I'll have any grief from Center if I call them up ahead of time and explain the purpose of the flight.

I think I'll go up to 16-17k and reestablish Vy at that altitude prior to the trip and re-acquaint myself with that corner of the envelope.
 
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One other area to check is how high your system was certified to under FAR 91.411. Once you have determined that number .. is it legal to operate above that altitude?
 
Hate to use the "F" word in public but...

This exercise seems a little Foolish to me.

Been in the chamber, been plenty hypoxic many times, had the bends from unpressured flight at high altitude, had the O2 hangover to go with it all.

As an untrained participant in a single pilot vehicle, you are going to be the last to know when you're impaired, and even if you figure it out in time it might be too late. Bad decisions will be happening and you won't even care...

The comment from the controller to "try to break the record" sounds like a frat party challenge to a inebriated pledge. The fact that you accepted the challenge may be the only lasting proof of your impaired judgement.

Don't get me wrong. I'm not trashing the OP just for the fun of it, but I think this sort of experimentation is outside the realm of responsible piloting.

Be safe out there
 
Guy posts a cool story about climbing way up high in an airplane he built with his own two hands in his garage.

Gets crucified because he didn't know cannulas aren't suitable for going higher than 18K'.

I'm sorry. I don't get it. The mission here is to help others "Hey, you probably didn't realize it, but...". Instead, we eat our own.

And we wonder why numerous very well meaning and knowledgeable people have sworn off these forums.
 
KB, the least of my concern is the cannula above FL180. I didn't ask if he and plane were legal for Class A airspace- I hope so, or ask him to delete it and certainly not make it a YT video or social media it.

It's a cool story on first read, as you said. Then, a tell me about a time (TMAAT)/ I learned about flying from that (ILAFFT) entry.

It might actually benefit from a thread delete and ASAP form submittal depending on the back stories and any rating/s to potentially protect.

More brother's keeper from big brother than running around nekkid in my glass house throwing stones.
 
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-The OP brought O2 with him
-Used a pulse oximeter
-Readily admits he should have used a mask
-Used good judgement and headed down when he saw 80%
What more do you want?

I do not post often because as Kyle said “we eat our own”.
I still enjoyed his post. Maybe lighten up a bit.
 
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I think this one has run its course - and I doubt very many people will want to share stories of their flying experiences with some of the responses this one brought.

Civil questions were asked, and points made - then the piling on began.
 
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