More meteoric reentry thoughts Caleuche (28 Jan 2018 01:22 UTC)
Re: [TML] More meteoric reentry thoughts Tim (28 Jan 2018 02:15 UTC)
Re: [TML] More meteoric reentry thoughts Thomas Jones-Low (28 Jan 2018 02:33 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (28 Jan 2018 02:49 UTC)
Re: [TML] More meteoric reentry thoughts Tim (28 Jan 2018 03:08 UTC)
Re: [TML] More meteoric reentry thoughts Graham Donald (29 Jan 2018 12:12 UTC)
Re: [TML] More meteoric reentry thoughts Kelly St. Clair (29 Jan 2018 15:24 UTC)
Re: [TML] More meteoric reentry thoughts Graham Donald (30 Jan 2018 00:42 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (30 Jan 2018 05:31 UTC)
Re: [TML] More meteoric reentry thoughts Graham Donald (30 Jan 2018 10:22 UTC)
Re: [TML] More meteoric reentry thoughts Tim (30 Jan 2018 13:41 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (30 Jan 2018 22:07 UTC)
Re: [TML] More meteoric reentry thoughts Tim (31 Jan 2018 00:40 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (31 Jan 2018 01:39 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (31 Jan 2018 01:43 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (31 Jan 2018 05:12 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (31 Jan 2018 05:54 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (30 Jan 2018 22:26 UTC)
Re: [TML] More meteoric reentry thoughts Tim (31 Jan 2018 00:58 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (31 Jan 2018 05:18 UTC)
Re: [TML] More meteoric reentry thoughts Tim (31 Jan 2018 09:20 UTC)
Re: [TML] More meteoric reentry thoughts Thomas Jones-Low (31 Jan 2018 13:02 UTC)
Re: [TML] More meteoric reentry thoughts Bruce Johnson (31 Jan 2018 19:49 UTC)
Re: [TML] More meteoric reentry thoughts Bruce Johnson (31 Jan 2018 20:15 UTC)
Re: [TML] More meteoric reentry thoughts Tim (31 Jan 2018 22:46 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (28 Jan 2018 03:43 UTC)
Re: [TML] More meteoric reentry thoughts Phil Pugliese (28 Jan 2018 19:23 UTC)
Re: [TML] More meteoric reentry thoughts Kelly St. Clair (28 Jan 2018 19:43 UTC)
Re: [TML] More meteoric reentry thoughts Phil Pugliese (28 Jan 2018 20:11 UTC)
Re: [TML] More meteoric reentry thoughts Douglas Berry (29 Jan 2018 00:31 UTC)
Re: [TML] More meteoric reentry thoughts Edward Swatschek (28 Jan 2018 11:41 UTC)
Re: [TML] More meteoric reentry thoughts Ashley Greenall (28 Jan 2018 14:23 UTC)
Re: [TML] More meteoric reentry thoughts Jim Catchpole (28 Jan 2018 15:08 UTC)
Re: [TML] More meteoric reentry thoughts Rupert Boleyn (29 Jan 2018 02:33 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (29 Jan 2018 02:58 UTC)
Re: [TML] More meteoric reentry thoughts Rupert Boleyn (29 Jan 2018 03:10 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (29 Jan 2018 03:12 UTC)
Re: [TML] More meteoric reentry thoughts Kurt Feltenberger (29 Jan 2018 03:35 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (29 Jan 2018 03:42 UTC)
Re: [TML] More meteoric reentry thoughts Kurt Feltenberger (29 Jan 2018 03:55 UTC)
Re: [TML] More meteoric reentry thoughts Douglas Berry (29 Jan 2018 05:25 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (29 Jan 2018 06:35 UTC)
Re: [TML] More meteoric reentry thoughts Kurt Feltenberger (29 Jan 2018 06:56 UTC)
Re: [TML] More meteoric reentry thoughts Caleuche (29 Jan 2018 07:11 UTC)
Re: [TML] More meteoric reentry thoughts Tim (29 Jan 2018 08:59 UTC)
Re: [TML] More meteoric reentry thoughts Evyn MacDude (29 Jan 2018 03:33 UTC)

Re: [TML] More meteoric reentry thoughts Caleuche 30 Jan 2018 22:07 UTC

I mistakenly ran the model with 1.4 meters radius rather than 1.4 meters diameter, but otherwise modeled a sphere with radius 1.4 meters, subsonic drag coefficient 0.47 and transsonic drag coefficient 0.55, and supersonic drag coefficient 0.47 again (I need to fix that, spheres have very high supersonic drag coefficients), mass was modeled to be 104 kg for the sphere and 100 kg for the astronaut+spacesuit (the same as the traveller reentry kit) but going on with it:

Here is the plot from entry interface to touchdown:
https://i.imgur.com/APikZcR.png

And some of the extracted data:
https://i.imgur.com/zdxUmZG.png

Peak acceleration is just over 8g at around 20,000 meters altitude, and dynamic pressure peaks at that time too, at around 650 kPa (thanks to the fairly high mach number at that point). I'm using Mathematica's StandardAtmosphereData[] for pressure, temperature, atmospheric molecular density and speed of sound data. I'm presuming the air is an ideal gas.

Dynamic pressure remains below 12 kPa until altitude is ~58 km, though. I suppose the astronaut could "bail out" at that point but it's still over Mach 25.
​

​

-------- Original Message --------
 On January 30, 2018 5:41 AM, Tim <xxxxxx@little-possums.net> wrote:

>On Tue, Jan 30, 2018 at 12:31:26AM -0500, Caleuche wrote:
>>I'm not clear about some of the reentry procedure, the patent states
>> that the sphere is under very low absolute pressure and is obviously
>> not rigid, the returning astronaut will know it's safe to depart the
>> "vehicle" once the sphere starts to collapse under the higher
>> outside pressure of Earth's atmosphere. But reentry itself will
>> result in fairly high pressures at times
>>
> Not for something this light.  Even if it came in steeply enough to
> peak at 10 gee deceleration, the dynamic pressure would still be less
> than 20 kPa.  You can run the numbers on a (say) 100 kg sphere with
> about 1.4 m diameter to see that the expected peak deceleration for a
> typical shallow entry will be quite a bit less than that.
>
> The patent document states that it was designed to support up to
> 8.5 gees deceleration, with an internal pressure of 1.75 p.s.i.a (about
> 12 kPa).  So their figures are comparable with my back of the envelope
> numbers.  The bladder pressure was chosen to be that low so as not to
> exceed the internal pressure of a space suit and possibly restrict air
> flow during descent.
>
>
> - Tim
>
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