Re: Spaceship One - a partial sucess.

From: Brett Buck (buckbw_at_pacbell.net)
Date: 09/29/04 

Date: Wed, 29 Sep 2004 16:00:02 GMT

On 9/29/04 8:46 AM, in article
bruce-16F9DE.03463930092004@copper.ipg.tsnz.net, "Bruce Hoult"
<bruce@hoult.org> wrote:

> In article <415bd5aa.32267152@supernews.seanet.com>,
> fairwater@gmail.com (Derek Lyons) wrote:
>
>> gherbert@retro.com (George William Herbert) wrote:
>>
>>> Derek Lyons <fairwater@gmail.com> wrote:
>>>> First returns; the 100km mark was broken, ascent phase control
>>>> problems remain.
>>>
>>> This time the control problems were at the end of the burn,
>>> but it looked pretty exciting for a bit there...
>>
>> 20 odd rolls according to Miles O'Brien on CNN, somewhat more severe
>> than last time.
>
> Was it the same direction?
>
> My crazy wild-eyed theory: there's a swirl in the N2O entering the
> combustion chamber, or there is a spiral pattern in the way the solid
> fuel is cast or something like that.
>
> -- Bruce

   That's possible, but the "swirl" as a direct source of roll torque would
seem to be insufficient. Much more likely, to me, is a thrust vector
misalignment in yaw, driving it to a static yaw angle of attack, and then
the dihedral effect rolls it. That could be a powerful effect, far more
powerful than the swirl.

   I don't have any direct professional experience with hybrids, but I would
be amazed if it's worse in "swirl" than your average liquid engine. And
that's always proven to be small to the point of negligible.

    But he thrust vector misalignment could very easily be a few degrees,
and is very often just ignored (!) (I have a few stories that have to wait
40 something years to tell) and that could be more than enough.

     Brett