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Space Forum / Space History / June 2004Mike Melville wearing no pressure suit
I noticed from the interior, in-flight shots from Spaceship One that the pilot was not wearing a full pressure suit. I was under the impression that a full pressure suit is required by the FAA for all occupants of an aircraft operating above 50,000 feet. ??? > I noticed from the interior, in-flight shots from Spaceship One that > the pilot was not wearing a full pressure suit. I was under the > impression that a full pressure suit is required by the FAA for all > occupants of an aircraft operating above 50,000 feet. ??? SS1 was initially (and may still be) operating under an experimental aircraft certification; lots of stuff in the FAR's don't apply to experimental aircraft. Since then, the FAA has been working to establish much-less-restrictive type certification requirements for suborbital spacecraft similar to SS1 which would allow them to operate without subjecting them to the restrictive requirements of most civil aircraft (especially large, passenger-carrying aircraft). I don't think that process is anywhere near complete. However, they have at least come up with workable regs for suborbital launches, even if they haven't finished the process for the craft themselves.  SignatureHerb Schaltegger, B.S., J.D. Reformed Aerospace Engineer Columbia Loss FAQ: <http://www.io.com/~o_m/columbia_loss_faq_x.html> >> I noticed from the interior, in-flight shots from Spaceship One that >> the pilot was not wearing a full pressure suit. I was under the [quoted text clipped - 4 lines] >aircraft certification; lots of stuff in the FAR's don't apply to >experimental aircraft. SS1 is now a launch vehicle (a suborbital one), operating under launch- vehicle licensing. Which, again, takes the FARs largely out of the picture. By the way, Concorde routinely operated above 50kft. >Since then, the FAA has been working to establish much-less-restrictive >type certification requirements for suborbital spacecraft similar to SS1 >which would allow them to operate without subjecting them to the >restrictive requirements of most civil aircraft... Note a distinction of terminology: certification is an *aircraft* process. It simply doesn't apply to launch vehicles. Launch vehicles get licensed, not certified. (Someday there will probably be certification for launch vehicles too, but not soon. Today's certification process is impossibly onerous for a new industry; it's almost impossible for even innovative *aircraft* builders to get their designs through certification now, as Burt Rutan could tell you -- it's not an accident that he dislikes the FAA.) The dividing line between an aircraft and a suborbital launch vehicle, by the way, is rocket power with thrust exceeding aerodynamic lift for at least 50% of powered flight. (And the dividing line between suborbital and orbital is whether the "vacuum instantaneous impact point" -- where the thing would hit if you suddenly zeroed out thrust, lift, and drag -- ever deliberately leaves the Earth's surface.) (At Space Access 03, where the FAA first announced these definitions, some cynic pointed out that it is probably possible to reach a free-return lunar-flyby trajectory without the vacuum instantaneous impact point ever leaving Earth. "And then you could need to make an emergency landing...") Signature"Think outside the box -- the box isn't our friend." | Henry Spencer -- George Herbert | henry@spsystems.net > >> I noticed from the interior, in-flight shots from Spaceship One that > >> the pilot was not wearing a full pressure suit. I was under the [quoted text clipped - 8 lines] > vehicle licensing. Which, again, takes the FARs largely out of the > picture. Thanks for that bit; I couldn't remember whether they were still operating under their "experimental" designation or not. Under the FAA's AST regulations it's pretty clearly a "Reusable Launch Vehicle." > By the way, Concorde routinely operated above 50kft. > [quoted text clipped - 11 lines] > now, as Burt Rutan could tell you -- it's not an accident that he dislikes > the FAA.) I'm sure that's no accident. But he (and Paul Allen, and John Carmack and Elon Musk and anyone else who's ever sunk a dime of personal money into developing a launch vehicle, reusable or not) better get used to the idea of type certification for launch vehicles. It *will* happen, sooner or later. 14 CFR 431.1 - 431.93 already contain fairly detailed requirements for a vehicle to meet prior to issuance of a launch license (either kind - mission-specific or operator license). > The dividing line between an aircraft and a suborbital launch vehicle, by > the way, is rocket power with thrust exceeding aerodynamic lift for at > least 50% of powered flight. (And the dividing line between suborbital > and orbital is whether the "vacuum instantaneous impact point" -- where > the thing would hit if you suddenly zeroed out thrust, lift, and drag -- > ever deliberately leaves the Earth's surface.) Do you have a cite? I'd like to take a look at those definitions. I didn't see anything similar in a (quick) overview of AST's final rules. The current final regulations for the AST define "launch vehicle" as "a vehicle built to operate in, or place a payload in, outer space or a suborbital rocket." "Reusable launch vehicle" is defined as "a launch vehicle that is designed to return to Earth substantially intact and therefore may be launched more than one time or that contains vehicle stages that may be recovered by a launch operator for future use in the operation of a substantially similar launch vehicle." "Launch vehicle" is "a vehicle built to operate in, or place a payload in, outer space or a suborbital rocket." Of course, being the government, "suborbital rocket" is not defined (at least not in the same section). _See_ 14 CFR 401.5 (If LaDonna is lurking, THAT'S how you give a citation, dear). > (At Space Access 03, where the FAA first announced these definitions, some > cynic pointed out that it is probably possible to reach a free-return > lunar-flyby trajectory without the vacuum instantaneous impact point ever > leaving Earth. "And then you could need to make an emergency landing...") Heh. That's funny! SignatureHerb Schaltegger, B.S., J.D. Reformed Aerospace Engineer Columbia Loss FAQ: <http://www.io.com/~o_m/columbia_loss_faq_x.html> >Do you have a cite? I'd like to take a look at those definitions. I >didn't see anything similar in a (quick) overview of AST's final rules. ...You're asking *Henry* for a cite?? Hey, this ain't LaHenry, Herb! Take his word for it or else! :-) OM Signature"No bastard ever won a war by dying for | http://www.io.com/~o_m his country. He won it by making the other | Sergeant-At-Arms poor dumb bastard die for his country." | Human O-Ring Society - General George S. Patton, Jr In article <ud5hd0942nsjq64pd8r17ootrh4qfa9vmk@4ax.com>, OM <om@our_blessed_lady_mary_of_the_holy_NASA_research_facility.org> wrote: > >Do you have a cite? I'd like to take a look at those definitions. I > >didn't see anything similar in a (quick) overview of AST's final rules. > > ...You're asking *Henry* for a cite?? Hey, this ain't LaHenry, Herb! > Take his word for it or else! :-) Here (in stark contrast to questioning "LaDonna"), it's a request for information rather than a challenge. I trust Henry will perceive the difference. SignatureHerb Schaltegger, B.S., J.D. Reformed Aerospace Engineer Columbia Loss FAQ: <http://www.io.com/~o_m/columbia_loss_faq_x.html> >Here (in stark contrast to questioning "LaDonna"), it's a request for >information rather than a challenge. I trust Henry will perceive the >difference. ...Here Herb misses the satire, and you guys whine about me missing *one* Star Trek reference. May you all have to sleep with LaBimbo tonight... OM Signature"No bastard ever won a war by dying for | http://www.io.com/~o_m his country. He won it by making the other | Sergeant-At-Arms poor dumb bastard die for his country." | Human O-Ring Society - General George S. Patton, Jr In article <k19hd014790l5l54akj2he90o5vnbomsie@4ax.com>, OM <om@our_blessed_lady_mary_of_the_holy_NASA_research_facility.org> wrote: > >Here (in stark contrast to questioning "LaDonna"), it's a request for > >information rather than a challenge. I trust Henry will perceive the [quoted text clipped - 6 lines] > > OM Geez, I forget one little smiley and see what happens . . . ;-) SignatureHerb Schaltegger, B.S., J.D. Reformed Aerospace Engineer Columbia Loss FAQ: <http://www.io.com/~o_m/columbia_loss_faq_x.html> >>Here (in stark contrast to questioning "LaDonna"), it's a request for >>information rather than a challenge. I trust Henry will perceive the [quoted text clipped - 4 lines] > > May you all have to sleep with LaBimbo tonight... On a completely unrelated sidenote. I recently figured out how to work the controls on the Thunderbird usenet reader filters, having never tried before. A single solitary filter, to delete posts by one author, has increased the readability of these newsgroups extraordinarily. Now, if a certain other person whom I shall dub "rabid OM in training" would keep it to a dull roar I could probably get by very satisfactorily without having to add any other filters. Trolls need to be fed, folks, keep that in mind. >>Do you have a cite? I'd like to take a look at those definitions... > >...You're asking *Henry* for a cite?? Hey, this ain't LaHenry, Herb! >Take his word for it or else! :-) Nah, it's a legitimate request -- if nothing else, I have been known to make mistakes -- even if I'm not always able to supply one. Signature"Think outside the box -- the box isn't our friend." | Henry Spencer -- George Herbert | henry@spsystems.net >I have been known to make mistakes ...And some of us have the T-Shirts to prove it :-) :-) :-) OM Signature"No bastard ever won a war by dying for | http://www.io.com/~o_m his country. He won it by making the other | Sergeant-At-Arms poor dumb bastard die for his country." | Human O-Ring Society - General George S. Patton, Jr [...] > I have been known to make mistakes > -- even if I'm not always able to supply one. Some of us keep a large inventory of mistakes, so that we can supply one on a moments notice. /dps P.S. TV's Pat O'Brien *did not* get his from *my* inventory! > [...] >> I have been known to make mistakes >> -- even if I'm not always able to supply one. > > Some of us keep a large inventory of mistakes, so that we can supply > one on a moments notice. I used to have a large strategic reserve of mistakes, and then I had my final exams... Signature-Andrew Gray andrew.gray@dunelm.org.uk > In article <ud5hd0942nsjq64pd8r17ootrh4qfa9vmk@4ax.com>, > OM <om@our_blessed_lady_mary_of_the_holy_NASA_research_facility.org> [quoted text clipped - 6 lines] > Nah, it's a legitimate request -- if nothing else, I have been known to > make mistakes -- even if I'm not always able to supply one. Uh, Henry: Is that a cite or a mistake??? (sorry, couldn't resist) :-) Signature-Willy >> The dividing line between an aircraft and a suborbital launch vehicle, by >> the way, is rocket power with thrust exceeding aerodynamic lift for at [quoted text clipped - 4 lines] >...Of course, being the government, "suborbital rocket" is not defined (at >least not in the same section). That is exactly the definition you want, of course. :-) Precisely where it shows up in the current documents, I'm not sure -- it's been a while since I looked at them and this is a recent development. The definition was unveiled at Space Access 03, but only quite recently did it actually get cleared and blessed all the way through the FAA bureaucracy. (George Nield, the #2 man in FAA-AST, announced that at Space Access 04; he added that the same definition is in HR-3752.) Signature"Think outside the box -- the box isn't our friend." | Henry Spencer -- George Herbert | henry@spsystems.net > [...] (And the dividing line between suborbital >and orbital is whether the "vacuum instantaneous impact point" -- where >the thing would hit if you suddenly zeroed out thrust, lift, and drag -- >ever deliberately leaves the Earth's surface.) >(At Space Access 03, where the FAA first announced these definitions, some >cynic pointed out that it is probably possible to reach a free-return >lunar-flyby trajectory without the vacuum instantaneous impact point ever >leaving Earth. "And then you could need to make an emergency landing...") Even more pedantically, many (most?) orbits around the sun, bounded roughly by Venus and Mars, have a "vaccuum instantanous impact point" on the Earth's surface. It's just a few million, or billion, years in the future. You might be able to launch into one of these orbits without your impact point leaving Earth. Lou Scheffer >>...it is probably possible to reach a free-return >>lunar-flyby trajectory without the vacuum instantaneous impact point ever [quoted text clipped - 4 lines] >on the Earth's surface. It's just a few million, or billion, years >in the future... Unfortunately, not so. Near misses are much more likely than direct hits, and a few near misses can change the orbit greatly. Simulations say that the most likely long-term fate for an object wandering around the inner solar system is for its orbit to intersect the Sun, and the second most likely is to be ejected from the solar system by a Jupiter encounter. Hitting one of the inner planets is a distant third. Signature"Think outside the box -- the box isn't our friend." | Henry Spencer -- George Herbert | henry@spsystems.net > >>...it is probably possible to reach a free-return > >>lunar-flyby trajectory without the vacuum instantaneous impact point ever [quoted text clipped - 11 lines] > likely is to be ejected from the solar system by a Jupiter encounter. > Hitting one of the inner planets is a distant third. This may be true for inner system orbits in general, but orbits starting from the Earth's surface are a special case (basically, since they are guaranteed to return to the earth's vicinity with low relative velocities). In paper http://arxiv.org/abs/astro-ph/0207316 the authors look at the fate of rocks that might be ejected from the Earth's surface by a meteorite impact. Of those that went into heliocentric orbits with low escape velocities, 61% re-impacted the earth within 5000 years (the limit of their simulation). With larger velocities few impacted the Earth in their study, but the simulation was too short to determine their ultimate fate. Lou Scheffer >In paper http://arxiv.org/abs/astro-ph/0207316 >the authors look at the fate of rocks that might be ejected from the [quoted text clipped - 3 lines] >velocities few impacted the Earth in their study, but the simulation >was too short to determine their ultimate fate. ...Weren't they supposed to have begun work on a follow-up study to account for longer duration and/or larger impacts? After two years you'd figure they'd made progress on this by now. OM Signature"No bastard ever won a war by dying for | http://www.io.com/~o_m his country. He won it by making the other | Sergeant-At-Arms poor dumb bastard die for his country." | Human O-Ring Society - General George S. Patton, Jr >...In paper http://arxiv.org/abs/astro-ph/0207316 >the authors look at the fate of rocks that might be ejected from the >Earth's surface by a meteorite impact. Of those that went into >heliocentric orbits with low escape velocities, 61% re-impacted the >earth within 5000 years (the limit of their simulation). Examined closely, however, the data tells a different story. That 61% number is valid only for rocks that leave Earth at *exactly* escape velocity -- a Vinfinity of 0 -- which is a rather specialized case. Because escape from Earth's gravity subtracts a fixed amount of energy rather than a fixed amount of velocity, an initial velocity only slightly higher than escape velocity yields quite a substantial Vinfinity. Raise the initial velocity by a mere 1% and Vinfinity becomes about 1.6km/s... which puts us in a region of their simulation where the fraction impacting is only 3-4%. Gladman et al, "The exchange of impact ejecta between terrestrial planets", Science 271 p1387 (8 March 1996), looked at Mars rocks at a range of reasonable ejection velocities, and found 40% going into the Sun within 100Myr, about half that encountering Jupiter, a similar percentage still in space, and rather smaller percentages hitting each terrestrial planet (including Mars). Signature"Think outside the box -- the box isn't our friend." | Henry Spencer -- George Herbert | henry@spsystems.net > >...In paper http://arxiv.org/abs/astro-ph/0207316 > >the authors look at the fate of rocks that might be ejected from the [quoted text clipped - 5 lines] > number is valid only for rocks that leave Earth at *exactly* escape > velocity -- a Vinfinity of 0 -- which is a rather specialized case. Yes, but this is exactly the case you need for the original problem, which is "are there trajectories which include heliocentric orbits where the impact point never leaves Earth?" I think the answer is yes, and they should be easy to find. The basic idea is to accelerate straight up in a random direction until Vinfinity = +epsilon, and you have a 61% chance of finding one. At the beginning you will have negative Vinfinity, and your impact point will be on Earth if your engine suddenly quits. As you approach Vinfinity = 0, your impact time will start moving very fast into the future, as your orbits get very very long, but I think by tweaking your trajectory you can always keep it on Earth. By Vinfinity = 0, your impact point will still be on Earth, but thousands of years in the future. Then adding some the last epsilon while keeping the impact point on Earth should be possible. Of course, to make this work in practice may not be possible, except for a few orbits that intersect the Earth rather quickly, within a few decades. As JPL has found when trying to predict asteroid orbits, due to things like the Yarkovsky effect, you'll need the spin state, the thermal properties of the craft, and how these will change with time as the paint degrades, and so on. Plus if the spacecraft has any active systems at all, you'll have gas leaks, waste heat rejection, and so on. All in all, I don't think the FAA needs to rush to change their definition. Lou Scheffer >Yes, but this is exactly the case you need for the original problem, >which is "are there trajectories which include heliocentric orbits >where the impact point never leaves Earth?" I think the answer is >yes, and they should be easy to find. I think it's pretty straightforward to find heliocentric trajectories where the impact point *probably* never leaves Earth. I think you'd have a much harder time establishing that it *definitely* never leaves Earth, especially to the satisfaction of the FAA! >...At the beginning you will have negative Vinfinity... Dept of Nitpicking: an imaginary Vinfinity, actually. >All in all, I don't think the FAA needs to rush to change their >definition. Oh, I'm sure that if anybody actually *tried* even the lunar-flyby version, there might be some small delays :-) in the licensing process. Signature"Think outside the box -- the box isn't our friend." | Henry Spencer -- George Herbert | henry@spsystems.net > I noticed from the interior, in-flight shots from Spaceship One that > the pilot was not wearing a full pressure suit. I was under the > impression that a full pressure suit is required by the FAA for all > occupants of an aircraft operating above 50,000 feet. ??? Not by the FAA. The USAF and USN, and probably most other AIr FOrces, require it if flight is _planned_ to exceed 50,000'. Military aircraft usually aren't pressurized to the same differential pressure as an airliner - an F-4's pressurization system works at a 5.5 psi differential pressure, for example, and that gives you a cabin altitude of about 21,000' at 50,000'. If pressure suits were required by the FAA, then every transatlantic Concorde passenger would have had to wear one. - they generally cruise-climbed to somewhere around 55,000'. SignaturePete Stickney A strong conviction that something must be done is the parent of many bad measures. -- Daniel Webster > I noticed from the interior, in-flight shots from Spaceship One that > the pilot was not wearing a full pressure suit. I was under the > impression that a full pressure suit is required by the FAA for all > occupants of an aircraft operating above 50,000 feet. ??? Gulfstream G550's are certified to operate at 51,000ft... and no one has to wear pressure suits (flight crew would be required to though). |
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