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-   -   Ceiling (https://vansairforce.net/community/showthread.php?t=184290)

kaweeka 07-04-2020 11:01 AM

Ceiling
 
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

Pilot135pd 07-04-2020 11:06 AM

Quote:

Originally Posted by kaweeka (Post 1443963)
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.

SPX 07-04-2020 11:24 AM

Were you level long enough anywhere to allow the airplane to accelerate and note your TAS?

BobTurner 07-04-2020 11:42 AM

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?

kaweeka 07-04-2020 01:15 PM

Quote:

Originally Posted by SPX (Post 1443968)
Were you level long enough anywhere to allow the airplane to accelerate and note your TAS?

No. I headed down but at 38% power, it is unlikely to be impressive.

kaweeka 07-04-2020 01:17 PM

Quote:

Originally Posted by BobTurner (Post 1443970)
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.

rvbuilder2002 07-04-2020 05:02 PM

I think the ?book? values are extrapolated from test data for what the ceiling would be at gross weight. Anything lighter would allow higher.

Taltruda 07-04-2020 05:27 PM

Quote:

Originally Posted by BobTurner (Post 1443970)
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?

SPX 07-04-2020 05:47 PM

Quote:

Originally Posted by Taltruda (Post 1444058)
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.

Taltruda 07-04-2020 06:11 PM

Quote:

Originally Posted by SPX (Post 1444060)
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?


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