I love it when science and comedy come.together!

On-your -six

You nailed it but this is a fun thread

Cheers bob T

Just read the whole thread, awsome! Even if you work the numbers to accurately predict the results of variations on this experiment,
(like the Japanese already have before deciding to go ahead and actually fund the experiment), the main range of responses guys have posted still teach an awful lot about the prevalence of certain misconceptions in popular culture!

Example: Assuming a stable orbit at launch that is lower and therefore faster than geo-synchronous, and only slight velocity changes imparted by the launch (like we're talking about here), orbital mechanics 101, or even basic physics shows that:
>Launching inward takes you forward from your launch vehicle's trajectory (not down).
>Launching outward takes you backward.
>Launching forward takes you outward.
>Launching backward takes you inward.
Only 2 or 3 guys out of the first 48 posts seemed to understand this!

Now, here is a little tidbit that may help open the minds of the guys who jump to the "its gonna burn up / blow apart of course" conclusions instead of managing to actually think it through successfully.

>Picture said balsa (or paper etc) airplane having only the mass of one atom instead of one ounce. Our heroic astronaut throws it backward to start its historic journey back down to the rest of our artfull, brilliant tribe of balsa and paper airplane throwing monkeys. Our cutting edge, high tech test vehicle hurtles along at the obligatory bazillion mph forward, and say, a mind blowing 50 mph downward. After a relatively short period (on a scale compared to the age of universe) in which humanity watches Superbowl commercials, eats popcorn, watches paint dry, and takes a nap, eventually our hotrod collides brutally with a whopping atmospheric density of ONE atom per cubic yard, then miles deeper into our gravity well, one atom per cubic foot, miles still further inward, one per cubic inch etc.
Nothing that is not made of unobtanium could possibly survive this kind of soul crushing torture test right?
OH, Wait! I totally forgot! the first atom it hit absorbed half its kinetic energy, and cut its speed by half! (forgive me, I'm assuming it really centerpunched that evil mother'), and again with the next atom, and the next etc.

Now..., can some more of us guys glimpse the deeper understanding that there IS a directly proportional relationship between the re-entry vehicle's [[mass divided by cooling surface area] multiplied by drag coefficient], and how much kinetic heating is caused by re-entry; and consequently whether or not any heat shielding is required to survive the mission?

Really, the main thing left to do is a proper set of engineering calculations to determine exactly what numerical constant we need to beat
(for a given re-entry trajectory), to shed heat fast enough to stay under a given material's maximum allowable temperature,
and the Japanese have already done that... They decided to fund the experiment, the principle actually has far reaching potential to lower vehicle and thusly mission costs .............

Remember boys and girls, your mind is a muscle, so always do some stretching before you think you can power lift without hurting yourself!

Best regards to all, Chuck Roundy

What if we used METRIC balsa?

It is an amazing concept when you think about it. Consider an astronaut launching a 1 kg (2.2 lb) Craftair Butterfly toward earth. It's moving approximately 7800 meters per second as it majestically tumbles away from the shuttle, the sun glinting off its flat bottom wing sections. That dainty little craft is packing about 30 million joules of energy from speed alone which equates to 30 million watts of power it will need to dissipate before it glides to earth. (This ignores potential energy from that weight up at the shuttle orbit height.) Assuming its surface area can safely dissipate 150 watts by radiation (a total guess), it's descent must take more 56 hours. It might be possible if it goes in at the right angle, but unfortunately, gravity starts acting on it more and it starts to speed up in the downward vector. All-in-all, still a very interesting topic! I think there are many of us on the forum that would love to see a Butterfly softly land in our back yard after space flight. With that much energy though, it seems unlikely that it could slow down fast enough to survive.

thailazer, well said -but- unlike your magnificently lght wing loading Craftair Butterfly example, the thread starter's scenario regards thin sheet balsa gliders which have a drasticly lower compound ratio of [[mass divided by heat radiating surface area] multiplied by drag coefficient] than a built up structure. Consider it again.

Metric balsa is very hard to find! It is only grown in the Metrictrainien forest, there is only one known tree deep in the forest gaurded by the Muttnics tribe and are known to be cat eaters! The Mutts as they are called go as far back as 5 years when one of the local towns people married his long time girlfriend Nancy Beldman! Back to back they faced each other because Nancy was on the track team so she was able to out run the locals till one came up with a plan! The plan was well thought out it took months and months to make his plan work, So one day or maybe it was the day before? he had put on his uncle Willies ape suit and as Nancy ran past him knowing it was really one of the locals in uncle Willies ape suit tripped her and was engaged and married before the wounds healed! Now they and thier brood the Mutts gaurd the metric balsa tree in hopes of someday turning it into a 7-11! Mutts are some of your nicest people till you cross them by not buying something and still using the Metrictrainien forest as a bathroom! I know this to be all facts, I asked my Ex girlfriend and she said yes!

And this is why I think a Balsa glider would burn and a solid diamond metric one going the other way would not!

I take back everything I said and will henceforth consider hairy46 as my intergalactic guide/guru to the meta-physical.

Right on and entirely correct. I know because I happen to have one of their dogs.

Wait......I'm gonna be pissed at all of you if I see my taxes go up due to some new NASA experiment.

Sorry guys, there will be no tests to confirm the probability of a balsa glider re-entering the earth's atmosphere from space. Due to the pending regulatory actions of the FAA, the glider qualifies as an sUAS and as such is looked upon as a considerably dangerous non-commercial "model airplane". It would violate the maximum 400 foot rule that the FAA is recommending be strictly adhered to by all models and it could potentially violate the pending 100mph limit that the FAA wants to initiate. You guys will just have to modify your "Real-Flight G5" flight simulation parameters to test the theory. But be careful here too as you may be suspected of developing some devious plot to use gliders from space to some no good end, like balsa splinters raining down on an unsuspecting populace below, or some hog rot like that.

Happy Flying!

Loopman

now that's funny

An object no matter what the mass must enter at the right trajectory and velocity or it will bounce off the atmosphere. As the object slows down it trades speed for heat and the paper or balsa would heat up too much and burn up.


Jeff

I have a feeling that alot of you folks will be surprised by the results.

Entry to earth from orbit does not matter, as it already is in orbit and needs a shove to slow the orbit and it will fall, eventually but it will take a long time for that little sucker to make reentry, my assumption longer than a month (no thrusters) (Apollo had to enter earth from beyond factors that make the gravity bounce real)

(Please keep in mind, all the shuttle does is slow down and she starts to drop to lower orbit until the big double boom is heard and she is on the ground)

I strongly believe that a Glider chucked from space will fair, as long as it does not end up in the path of a Cyclone or Hurricane...
If a little paper origami thingy can make it, then yes a lightly wing loaded glider can as well.


I await the protest.

Hey here is another question, how many of you think that Earths balancing act with summer and winter has anything to do with global warming, I for one think all folks have not paid enough attention to this factor, as they feel it does not matter. Take for example, a ball or something swing it above your head, eventually it is going to stop, same with a gravitational magnet suspended what ever.

OH dang.. Something else to ponde while the temp is below zero with 20 mph winds.. Fact is stranger than truth!![:-]

Well, in the original question, the OP asked
So we are not talking about a degrading orbit. We are talking about a downward (or more accurately, an earthward) throw.

Now, if we disregarded all other factors like gravity, air friction and the speed at which they are traveling, and if we said that the glider was a dart or other non-flying object and it was thrown at 10mph, Low-earth-orbit is only about 70 miles up, so the dart would reach the surface in about 7 hours.

So it's not a matter of how many days would it take for the orbit to degrade, the plane was thrown earthward.

For one I do not believe in global warming, When we were kids they was called seasons! Now if it dont snow its called global warming if it does snow its caused by global warming and so on and so on! We are already at a hundred and fifty percent of snow pack and we have not even got to the really snow season yet! Right now if ole Al was preaching global cooling he might get more takers, I for one will not drink the Al coolaid! Now back to the Balsa glider thingy.

I have a recent arrival of an alien being from a moon orbiting the planet zelbot staying with me at my house. He is laughing his, what would be his *****, off if he had one... He says you guys have it all wrong... He says that we can do the experiment this afternoon and get back to you... in the mean time he seems to be very interested in the xxx sites... and my credit card is maxed out.

BTW; Xpelerotian says to say hello to everyone.

Ok, fair enough on the way the glider is introduced to the atmosphere. We know that it is being introduced as fast as we can propel it via hand from the shuttle. Of course the astronaut will or can be braced against the shuttle, Canada Arm, or Station and or Station Canada Arm.

But that does bring wing loading and other factors into play when we are considering a balsa glider, how much do dem things weigh?

Shuttle, I think it is a few tonnes, Apollo capsule, again a few tonnes. Tonnes is a lot of weight, that in the end has to slow down to share the same falling speed as a ball on the surface. We know the newtons golden apple, and how all items fall at the same speed.

The shuttle has a pretty small wing btw, not meant to create a heck of a lot of lift by any means compared to other fixed wing objects, just a giant brake is what bottom is.
(I think here I may be wrong, but just food for thought)

Considering this, I believe the glider will tumble for a bit flutter back into a glide slope as long as it is self righting and glide like a bald eagle on a summer day till it touches down.


Fair argument I am coming back with?

I don't know why the beauty of it working is so appealing ...

But the idea of it working ,against so many odds , just makes me smile on a cold winter day...

I think we should get Nasa to try it. But then again, I guess we'd have no way to track it

If not NASA, it may be a marvelous Metrictrainien Muttnicean model mission!

I believe that thing can be tracked, but it is a matter of how long we can get a battery to last , perhaps solar cells or charger on wing with out increasing the weight beyond what a hobby person would encounter.

The lowest altitude for a shuttle orbit has been 155 miles up, at a speed of 17,500 mph give or take. Even with the chuck glider thrown straight down at 100 mph, the combined speed would not bring the glider low enough to engage any meaningful atmosphere. All it would do in put the glider model into a slight different orbit that would be elliptical if launched from a circular orbit. So, from that point forward the glider would spend part of it's orbit higher than the launch platform, while other time would be lower. Both the shuttle and the glider would continue to orbit in the same plane until the shuttle deorbits.

Plenty of books on Astrodynamics, all reasonably complex.

Well, that is what I though would happen, no thrusters to giver a good shove, it not going down to fast anyways.

See, someone who knows his stuff.

What you are all forgetting is that the atmosphere does not exist in space so as soon as the astronaut stepped out of the air lock to throw it, it would either break apart at -1000 (if it was in shadow) or it would burn up right away from the sun