paper airplanes

[Magyar]

WOW How cool is this? A prototype paper plane was tested in a wind tunel and passed. making further studies possible to launch one from space and return to earth.

http://www.physorg.com/news125811160.html

[robinson]

Oh those Japanese.

[madurobob]

Just what kind of payload can a 7cm long paper airplane carry?

Cue the Micronauts! (http://en.wikipedia.org/wiki/Micronauts_%28comic_book%29)

[The Man]

http://www.physorg.com/news125811160.html



Suzuki and Toda use origami paper made of sugar cane fibers that are resistant to heat, wind and water. They spray a special coating onto the paper and then fold it into shuttles about 8 inches long and 4 inches wide that weigh about 1.05 ounces. How many shuttles will be released has not been decided.

The pair theorize that with the coating, rounded edges, a rounded nose cone and almost no weight, their craft will face very little of the heat-generating friction that causes most damage to vehicles re-entering Earth's atmosphere.


Actually, the majority of the heat generated during re-entry is due to gas compression and not friction. As the leading edges of the re-entry vehicle compress the atmospheric gases in its direction of travel the temperature of that compressed gas is greater then it was when uncompressed. This transfers kinetic energy due to the vehicles momentum into thermal energy, slowing the vehicle. Naturally, since the paper plane has “almost no weight” it would also have less momentum at a given velocity and thus less kinetic energy to dissipate as heat in order to slow it down. However since it appears to be specifically designed to reduce leading edge compression it would also decrease the kinetic energy lost by atmospheric compression. We may find the release of these paper shuttles only results in high speed, coated sugar cane fiber paper, darts impacting in unpredictable locations.


"Just imagine, children around the world would be anxiously waiting for the return of our origami shuttle, perhaps looking up into the sky from time to time," Suzuki said. "That would be great fun."


Yeah, until someone is impaled by a paper “space dart”.



At this point, the proposal faces just one challenge, but it's a potentially crippling one: There is no way to track the paper craft or predict when or where they may land.

Critics say that makes the test pointless. Yasuyuki Miyazaki, an aerospace engineer at Nihon University who is not involved in the project, said the paper shuttles might not come back at all, depending on the angle at which they enter the atmosphere.


So, we may not need to run for cover since the unique aspects of this particular re-entry object (low mass and lack of leading edge compression) may prevent it from entering the denser layers of the atmosphere, reaching the surface at all or only after slowing to the speed of conventionally thrown paper plane. High flying aircraft though may still have some risk of a high speed impact from such a re-entry object.

[rwguinn]

Excuse the heck out of me, but just how do you remove enough velocity to de-orbit by throwing the thing?
Contrary to popular belief, just letting go of something in orbit does not mean it falls to Earth.
What is the orbital velocity of the ISS?

[The Man]

Throw it in the opposite direction of the orbital velocity, effectively decelerating its orbital velocity. The plane would still need to face in the direction of the initial orbital velocity so it would have to be thrown backwards, but that does not present a problem.

[The Man]

Double post

[rwguinn]

Throw it in the opposite direction of the orbital velocity, effectively decelerating its orbital velocity. The plane would still need to face in the direction of the initial orbital velocity so it would have to be thrown backwards, but that does not present a problem.

Yeah.
A really hot baseball pitcher, standing on Earth, with the mound to help him, can impart a Delta-V of 154 ft/sec (47 m/sec).
That won't cut it, at all. Lower the orbit, yes. De-orbit.? ha. It is to laugh
ETA:
Orbital velocity 0f ISS=27,744 km/hr = 7.7km/sec=7707m/sec. reduction of 2% whoopie

[Horatius]

Critics say that makes the test pointless.


When did, "Because it'd be really freaking cool!" stop being enough reason to do things?

:(

[The Man]

No one says that it must be thrown by a person. It could also be released from an already de-orbiting device similar to MIRV (Multiple Independent Re-entry Vehicle) deployment.

[rwguinn]

No one says that it must be thrown by a person. It could also be released from an already de-orbiting device similar to MIRV (Multiple Independent Re-entry Vehicle) deployment.

from the article.
"Astronaut Koichi Wakata, who has expressed personal interest in the project, would throw several origami shuttles into the wake of the international space station, which travels at Mach 20 some 250 miles above Earth - if the JAXA feasibility studies pan out, Suzuki said. "
Of course, it also say "Mach 20"--sound in space! Oh, dear.
There goes the movie premise...

[madurobob]

When did, "Because it'd be really freaking cool!" stop being enough reason to do things?

:(

Apparently it didn't. Witness Japan paying $300K/year to develop paper airplanes capable of re-entry from orbit.

[The Man]

from the article.
"Astronaut Koichi Wakata, who has expressed personal interest in the project, would throw several origami shuttles into the wake of the international space station, which travels at Mach 20 some 250 miles above Earth - if the JAXA feasibility studies pan out, Suzuki said. "
Of course, it also say "Mach 20"--sound in space! Oh, dear.
There goes the movie premise...

Sorry, I must have missed that in the article. I guess he is going to need at least one of those rubber band launchers that use to come with balsa wood planes, but with a bigger rubber band.

[rwguinn]

Sorry, I must have missed that in the article. I guess he is going to need at least one of those rubber band launchers that use to come with balsa wood planes, but with a bigger rubber band.
or a couple of Estes D-6's?

[The Man]

or a couple of Estes D-6's?

I think you've got somthing there, now that would be a "Because it'd be really freaking cool!" experiment.

[rwguinn]

I think you've got somthing there, now that would be a "Because it'd be really freaking cool!" experiment.
Science Project! Yee-haw!:D:D:D

[The Man]

Yeah.
A really hot baseball pitcher, standing on Earth, with the mound to help him, can impart a Delta-V of 154 ft/sec (47 m/sec).
That won't cut it, at all. Lower the orbit, yes. De-orbit.? ha. It is to laugh
ETA:
Orbital velocity 0f ISS=27,744 km/hr = 7.7km/sec=7707m/sec. reduction of 2% whoopie


Well, after doing some research I have found the Shuttles de-orbit delta V referenced from 300 Kilometers per Hour (186 MPH) to 220 Miles per Hour (354 KPH). 47 Meters per second equals 169 KPH or 105 MPH. At about half the Shuttles de-orbit delta V it’s still in the ballpark and not as far off as I would have thought.

[mhaze]

Yeah.
A really hot baseball pitcher, standing on Earth, with the mound to help him, can impart a Delta-V of 154 ft/sec (47 m/sec).
That won't cut it, at all. Lower the orbit, yes. De-orbit.? ha. It is to laugh
ETA:
Orbital velocity 0f ISS=27,744 km/hr = 7.7km/sec=7707m/sec. reduction of 2% whoopieRecalcuation please.

Orbital deacceleration may be considered to create heat on the descending capsule or object based on that item's "Ballistic coefficient", amoung other factors. This is simply weight per cross sectional area facing the oncoming wind. This is important in re entry because thin air at hypersonic velocity may have a low pressure (compared to ground on Earth) but the high velocity impact of the molecules creates tremendous heat.

It can be presumed that the ballistic coefficient of the paper airplane is extremely low.

Also, it is going to tumble, not retain the stability of the configuration, for a considerable part of the flight. This is because the airplane configuration that works subsonic (eg paper airplane) does not work supersonic.

Interesting experiment. I think it might be possible to place a small radio locator on the thing, toss a thousand of them out, and find one or two by flying around in the general area where they were to descend. Or a group of 2 types of objects might be thrown (designed so as to descend on the same general re entry path) some that were intended to burn up and thus provide visual tracking, others that were to descend and hopefully, some of them be found and examined.

Alternately, if they were aluminum foil and reflective, any fighter radar might pick them up.

[rwguinn]

Recalcuation please.

Orbital deacceleration may be considered to create heat on the descending capsule or object based on that item's "Ballistic coefficient", amoung other factors. This is simply weight per cross sectional area facing the oncoming wind. This is important in re entry because thin air at hypersonic velocity may have a low pressure (compared to ground on Earth) but the high velocity impact of the molecules creates tremendous heat.

It can be presumed that the ballistic coefficient of the paper airplane is extremely low.

Also, it is going to tumble, not retain the stability of the configuration, for a considerable part of the flight. This is because the airplane configuration that works subsonic (eg paper airplane) does not work supersonic.

Interesting experiment. I think it might be possible to place a small radio locator on the thing, toss a thousand of them out, and find one or two by flying around in the general area where they were to descend. Or a group of 2 types of objects might be thrown (designed so as to descend on the same general re entry path) some that were intended to burn up and thus provide visual tracking, others that were to descend and hopefully, some of them be found and examined.

Alternately, if they were aluminum foil and reflective, any fighter radar might pick them up.
You're working it backwards, guys.
The orbital velocity of the ISS is 7700 m/sec. That's where they plan on launching from...
By The Man's calculations, we gotta kill about 300ft/sec (100 m/s) to get it to re-enter at all, so the rubber band catapult might work--but that would be a HOT re-entry...

[drzeus99]

"Just imagine, children around the world would be anxiously waiting for the return of our origami shuttle, perhaps looking up into the sky from time to time," Suzuki said. "That would be great fun."

Sure...it's all fun and games until someone loses an eye

"LOOKOUT.....killer paper airplane. DUCK!!" :duck: