And that was a sphere with a radius of 3 meters. I'll rerun it at 0.7 meters a bit later.
​

​

-------- Original Message --------
 On January 30, 2018 5:38 PM, Caleuche <xxxxxx@sudnadja.com> wrote:

>That was a good catch!
>
> When I updated the air friction function to add mass as a parameter, I inadvertently updated the equation using that function with the older version of the function, so whatever was still in the kernel was the mass used.
>
> Hopefully this looks more reasonable:
> First, from entry interface to touchdown:
>https://i.imgur.com/B9g1ivF.png
>
> then, the data:
>https://i.imgur.com/1da7Jr4.png
>
> Peak dynamic pressure is now very low.
>
> ​
>
> ​
>
> -------- Original Message --------
> On January 30, 2018 4:40 PM, Tim xxxxxx@little-possums.net wrote:
>
>>On Tue, Jan 30, 2018 at 05:07:40PM -0500, Caleuche wrote:
>>>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
>>>That's not possible.  Drag = dynamic pressure * coefficient * area, so
>> with your figures the drag should be 2.2 MN, acting on a 204 kg object
>> thus yielding a deceleration of 1100 gee.  If you're getting 8 gee,
>> then you must be using a mass of 28 tonnes (or some similarly far-out
>> number elsewhere in the calculation).
>>A chunk of solid rock of the same size might have a mass of 28 tonnes,
>> and it would be physically reasonable for it to get down to 20 km
>> altitude before slowing significantly, but an astronaut in a bubble
>> won't.
>> - Tim
>>The Traveller Mailing List
>> Archives at http://archives.simplelists.com/tml
>> Report problems to xxxxxx@simplelists.com
>> To unsubscribe from this list please go to
>>http://archives.simplelists.com
>>
>
>
>The Traveller Mailing List
> Archives at http://archives.simplelists.com/tml
> Report problems to xxxxxx@simplelists.com
> To unsubscribe from this list please go to
>http://www.simplelists.com/confirm.php?u=0og3DHdoRHgL9lI7peOXYWnk6UF4c1zE
>