[AR] Re: supersonic retro (was Re: Re: Falcon 9 flight today)
- From: JMKrell@xxxxxxx
- To: arocket@xxxxxxxxxxxxx
- Date: Wed, 2 Oct 2013 16:30:58 -0400 (EDT)
In a message dated 10/2/2013 11:51:17 A.M. Pacific Daylight Time,
rsteinke@xxxxxxxxxxx writes:
On Wed, 02 Oct 2013 10:57:11 -0700
David Masten <dmasten@xxxxxxxxxxx> wrote:
> On 10/2/2013 10:32 AM, Henry Spencer wrote:
>> On Wed, 2 Oct 2013, Aplin Alexander T wrote:
>>> Musk pointed out during the post-flight Q&A that "I believe the first
>>> time that any rocket stage has attempted to do a supersonic
>>> retro-propulsion." Apparently it was successful (this was the 1st
>>> stage's initial 3-engine re-entry burn).
>> If you interpret "retro-propulsion" in the specific sense of firing
main
>> engines forward while still in detectable atmosphere, yeah, I think
>> that's true. Kistler was going to do it, but they never flew. Nor did
>> the shuttle ever do an RTLS abort.
> My understanding is that the concern is over the dynamics of the engine
>startup in the presence of strong shocks. From what I've seen and heard,
>SpaceX lit the engines well above any appreciable atmosphere.
>
> Dave
>
I think they are also worried about aerodynamic instability when flying
through the turbulent remnants of the exhaust plume.
Instability from the exhaust plume is not an issue during the three engine
retro burn. The aerodynamic forces during the single engine burn are
greater than any exhaust plume turbulence.
John Krell
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