Simple design for pressurized Sailplane

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paraplane

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This is basically a question for Bob (BoKu) is this ship maybe what inspired your thinking or similar to what you were thinking with Indigo Sky?
 

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Aerowerx

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Dumb question, not being a sailplane nerd;)....

Why would you need to pressurize? Wouldn't supplemental oxygen be enough?

You would have to carry the oxygen anyway, and then the extra weight of a pressurized cockpit.

I tried to Google it, but all I saw was the requirement for oxygen, not pressure. But did see that the B17 typically cruized at 28000 feet, and the P-51 could reach 42000. They were certainly not pressurized.
 

Aerowerx

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Aerowerx

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To restate my question, how high can you go before supplemental oxygen is not adequate and you have to have a pressurized cabin (or pressure suit)?

Would a "normal" sailplane, as shown in the OP, ever get that high?
 

proppastie

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To restate my question, how high can you go before supplemental oxygen is not adequate and you have to have a pressurized cabin (or pressure suit)?

Would a "normal" sailplane, as shown in the OP, ever get that high?
maybe if they were caught in the "polar vortex"
 

Mad MAC

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From memory, about 28,000 ft is the cutoff where 100% O2 wont maintain the required partial o2 pressure. That doesn't mean one can't go higher, just performance will decline (someone made it to 40,000 plus in a spitfire with out a pressure breathing rig but doesn't mean it was wise or pleasant).
 

Vigilant1

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To restate my question, how high can you go before supplemental oxygen is not adequate and you have to have a pressurized cabin (or pressure suit)?

Would a "normal" sailplane, as shown in the OP, ever get that high?
It is known as the Armstrong Limit. From memory--about 65k feet.
 

Mad MAC

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Also 25000 ft is the limit were one would survive (not function) without o2, hence changes in far23 for structursl requires for flight above at that level. Also o2 gives you a crtical failure case, while pressurization would give you a second level of safety, plus being much less fatiguing after5 hours plus.
 

lr27

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Judging by a standard atmosphere table, pure oxygen will match sea level air at somewhere between 35,000 and 40,000 feet. Pure oxygen at around 45,000 feet will match air at 10,000 feet.
 

lr27

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BTW, that sailplane in the picture doesn't look pressurized to me. There was a homebuilt called MOBA which had a similar "nose cone".
 

lr27

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Paul Bikle flew a Schweizer 1-23E above 46,000 feet in 1961.
 

Aesquire

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It's been decades since I took the course, but IIRC over 40,000 feet you wanted to be on a pressure mask to prevent blood chemistry problems, and a counter pressure "girdle" to prevent "Barotrauma", the fancy term for your lungs trying to pop like an over -inflated balloon.

Since nothing our class was going to fly went to the Armstrong limit, we just got the standard lecture and the cheerful anecdote about the Astronaut in a vacuum chamber who had a suit failure, and was unconscious by the time they could open the valves & get him under pressure. The last Thing he remembered before passing out was the sensation of the saliva on his tongue boiling.

That's a mental image that'll stick with you.
 

Aesquire

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A bit off topic, but if you ever have to bail out...

Skydivers in the ancient times I was jumping, ( the Da Vinci pyramid model? Not quite that old... ) routinely jumped from 12,500 feet to get a 60 second plummet before hopefully opening the chute. ;)

No need for O2 for the scant minutes that high.

And jumping out of a moving plane, typically for a Cessna 182, about 70+ knots, one actually only gets zero G for a few seconds before you accelerate to terminal velocity ( gotta love that term ) and are balancing gravity and airflow. The bottom drops out ( to your senses ) But quickly you are riding the wind, stabilized at about 120-200 depending on body position.

But from 22,000 out of a balloon, not only is the air enough thinner to make the time to terminal velocity noticeably longer, with zero airspeed, you really feel like you're dropping like a safe. They tell me my scream dopplered nicely.
 

Victor Bravo

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My friend Bob Harris had a two place Grob sailplane all set up for 50,000 feet with liquid oxygen and pressure suits and such. His glider altitude record attempts failed, and after several years he sold the sailplane. Then a short time later he was told that there was going to be record weather (strong mountain lee wave over the Sierra), and he got into his single place Grob glider, and went to 49,009 feet with only a "pressure demand" regulator. On that flight he finally took Paul Bikle's record, but not having an oxygen system suitable for those altitudes took a huge toll on his body. He had to quit any altitude flying, and was never "right" after that.

(During that period, Bob had a group of competitors who were trying to break Bikle's record. A group of airline pilots that called themselves "Flight Level 500", and they also had a Grob twin glider, pressure suits, etc. and waged a hilarious PR and advocacy campaign trying to get sponsorships and funding to support their record attempt. They went so far to infer that their competitor (Bob Harris) was a Commuist sympathizer. So myself and a few other of the sailplane guys hanging around during that time dubbed them "Noise Level 500", and to the day he died I always greeted Bob Harris as "Comrade Harris" :)

Another friend of mine trying to break Paul Bikle's record, Buddy Foote, took a Glasflugel 604 sailplane with a pressure demand regulator above 42,000 feet, descended too fast or had some sort of issue, and got himself a pretty bad embolism or the "bends", which ended his Marine Corps flying career before it even started. But the movie Top Gun had just come out, and Buddy decided that he still wanted to fly USMC fighters any way, and so (while still an enlisted mechanic going to college toward later flight training) he took an A-4 out for an unauthorized joyride over MCAS El Toro one night. )

Forgive the lurid trip down memory lane, but for whatever my non-scientific opinion is worth, the answer to "how high can you go us ing just supplemental oxygen" is pretty clear. About 40K if you're in good physical shape and you're not staying up there for hours. But you are still in a dangerous position, and it's no place for amateur level "sport flying".
 

proppastie

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I took my Mooney to 22K with oxy (obviously) to test out my OH engine. Still had about 50 ft. climb when I quit. New York Center was about to have a kitten. I probably was no closer than 10 miles to an airliner but everybody wanted to know where I was. I found it somewhat amusing. I did have to turn on the wing-level because I was at the edge of the stall and Mooney does not like to stall.
 

Victor Bravo

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VB, what did the Corps do to Buddy for taking the 104 out?
He spent a couple or three years in their jail and they decided not to spend any more money feeding him jail rations. Buddy had been a poster child for the Marines, a perfect mechanic and student, and his record-seeking in gliders impressed some high ranking Marine officers. So they had been sneaking him a lot of simulator time and ground school and possibly even some dual flights in A-4's, supporting his studies toward going to flight school as soon as he was done with college and could go to OCS. So he had a lot more experience and education on ther A-4 than just a ground-pounder mechanic. And several hundred hours as PIC in sailplanes.

My distant recollection is that his lawyers argued that he didn't even scratch the airplane, which is true, and that he didn't put anyone in any danger because he had not been buzzing the city and the airplane was not armed.

(He'd gone right out over the ocean and was essentially no danger to any one, but the airplane he stole was equipped with some ECM stuff that they thought maybe the Russians were trying to steal. And he never spoke a word on the radio to anyone and they didn't know that it was one of their own mechanics instead of a Russian spy. So they launched the AF alert fighters from March AFB with orders to destroy the aircraft. When he realized that two trained and armed people were going to splash the airplane, only then did he fly back over the city, knowing that they wouldn't shoot the A-4 down into houses.)

So he flew out his fuel and landed without so much as scuffing the tires. It was not possible for the USMC to legitimately argue that he was trying to harm any one or that harm was likely.

So he served out a short sentence, and was handed a dishonorable or less than honorable discharge. I'm pretty sure the FAA also suspended or revoked his civilian license as part of it. Last I heard he was flying professionally in China working for some startup that was using the Stemme motorglider as an orbiting cell phone provider or data link. But that was 20+ years ago. I met him because he crewed for me in a couple of sailplane races in 1984.
 
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