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Idea : possibly a little naive ... ?



 
 
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  #1  
Old July 31st 05, 11:06 PM
Davey K
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Default Idea : possibly a little naive ... ?

After playing with some sycamore seeds (helicopter seeds) with my
children, I thought of an idea for a satelite design. Shaped like a
large sycamore seed where the wing could be used as solar pannels and
the kernel to house the important bits. Bringing it back down to earth
by gently lowering its orbit until it starts to spin in the very thin
upper atmosphere. The rotation would bring it down slower and prevent
it from burning up.
I know that satelites go very fast, but if the atmosphere gets
gradually thicker, wouldnt a lot of the energy be converted into
spinning motion intead of heat ?

  #2  
Old August 1st 05, 06:25 PM
David Summers
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As I recall, the answer is no, very little energy ends up in a rotation
of any kind. In order for a large percentage of the energy to be in
rotation, the rotational speed would have to be near orbital speed,
which seems unlikely ;-}

Personally, I think rotatory landing is a much better idea than a
glider landing. You can use almost any field, and assuming late
deployment of the rotors you can have a stronger, denser unit. It's
not very during reentry, though - so the glider may yet win out...

  #3  
Old August 1st 05, 06:30 PM
Alain Fournier
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Davey K wrote:

After playing with some sycamore seeds (helicopter seeds) with my
children, I thought of an idea for a satelite design. Shaped like a
large sycamore seed where the wing could be used as solar pannels and
the kernel to house the important bits. Bringing it back down to earth
by gently lowering its orbit until it starts to spin in the very thin
upper atmosphere. The rotation would bring it down slower and prevent
it from burning up.
I know that satelites go very fast, but if the atmosphere gets
gradually thicker, wouldnt a lot of the energy be converted into
spinning motion intead of heat ?



One of the reasons why the European Hermes space plane was canceled
is that computational fluid dynamics analysis of its reentry
indicated some instability possibly leading to loss of control
of the ship. I suspect that evolution did not foresee hypersonic
flight when it designed the sycamore seed. My guess is that it
wouldn't spin in an orderly fashion.

Alain Fournier

  #4  
Old August 1st 05, 11:35 PM
Pat Flannery
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David Summers wrote:


Personally, I think rotatory landing is a much better idea than a
glider landing.



Look at the model Soyuz RV with the rotor blades...look at the _dents_
on the model Soyuz reentry module with the rotor blades:
http://www.astronautix.com/graphics/s/soyrotor.jpg ;-)
Seriously, the big problem is where you store the rotors during launch,
flight, and reentry.

Pat

  #5  
Old August 2nd 05, 12:54 AM
Pat Flannery
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Alain Fournier wrote:



One of the reasons why the European Hermes space plane was canceled
is that computational fluid dynamics analysis of its reentry
indicated some instability possibly leading to loss of control
of the ship.



That's one I never heard before; I thought it was increased weight would
lead to the necessity for a non-commercially optimized version of the
Ariane V being developed to carry it.
That, and the fact that they couldn't stop the unexplained meringue
shedding during ascent. :-)

Pat

  #6  
Old August 2nd 05, 01:32 AM
Alain Fournier
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Pat Flannery wrote:

Alain Fournier wrote:



One of the reasons why the European Hermes space plane was canceled
is that computational fluid dynamics analysis of its reentry
indicated some instability possibly leading to loss of control
of the ship.


That's one I never heard before;


It isn't THE reason but it was one of the reasons. I don't think
it was an insurmountable problem. But it was a problem that was
increasing the cost of the ship.


I thought it was increased weight would
lead to the necessity for a non-commercially optimized version of the
Ariane V being developed to carry it.


That too, it was many things.

That, and the fact that they couldn't stop the unexplained meringue
shedding during ascent. :-)


Is that meringue on the Shuttle external tank? Miam!!!

Alain Fournier

 




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