[AR] Re: FW: Re: clusters and reliability (was Re: Re: 3 no 4 no 5 legs.)
- From: "Hugh Blair-Smith" <hugh.bs@xxxxxxxxxxx>
- To: <arocket@xxxxxxxxxxxxx>
- Date: Mon, 25 Jan 2016 10:07:58 -0500
My question at the bottom ...
-----Original Message-----
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On
Behalf Of Chris Jones
Sent: Monday, January 25, 2016 12:52 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: FW: Re: clusters and reliability (was Re: Re: 3 no 4 no 5
legs.)
On 01/25/16 12:25 AM, Henry Spencer wrote:
On Sat, 23 Jan 2016, John Dom wrote:
[...]
Then, since the F-1 was already in development, it made sense to
baseline it for advanced first-stage concepts. By the time the
first stage had grown to a gigantic all-new design that needed
*five* F-1s,
[John Dom wrote:]
Elon once stated: bigger is better (but then that may have been
about the issue of 4 lighter legs instead of 3 heavier ones, not
sure).
More likely it was about engines and rockets in general. Many
people have regretted making rockets too small (the RD-180 Atlas
originally wasn't supposed to need solid strap-ons; Ariane 5 wasn't
supposed to need an LH2 upper stage), but only very rarely have
people regretted making a rocket too big.
In fact, the Saturn C-5 (later called the Saturn 5) originally had 4
F-1s in its first stage, and got the center engine when von Braun
realized/was informed that more lift capacity was required for a lunar
landing. Showing that great minds think alike (or payload designers
often underestimate their requirements) the Soviet N-1 first stage
originally was designed with 24 engines in the first stage, and grew by
the same 25% engine count (also by adding the additional engine(s) in
the center) when they needed "more power".
I read (in a secondary source, admittedly) that the expansion from 24 to 30
engines was driven by fault tolerance, and wrote in my book that the purpose
was to have a successful launch even when several engines failed. Granted
that if "several" means, say, three rather than six, both purposes would
apply, can you point me to a primary source that settles this point?
Hugh
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