[AR] Re: Issues with operating at low chamber pressure
- From: Norman Yarvin <yarvin@xxxxxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Mon, 5 Sep 2016 17:37:22 -0400
On Mon, Sep 05, 2016 at 07:10:08AM -0400, William Claybaugh wrote:
Norm:
A logarithm is an exponential function.
Not when you're talking about an "exponential effect", it isn't. An
exponential effect is a big effect that grows strongly as you increase
the factor in question; a logarithmic effect is a wimpy one that gets
ever-wimpier as the factor in question increases. In particular,
here, a 10% increase in Isp buys you a 10% increase in delta-v,
whereas a 10% increase in m_initial/m_final buys you less, at least
for launcher-like values of that ratio. (If, say, it starts out as
10, a 10% increase buys you about 4% more delta-v; or if it starts out
as 5, a 10% increase buys you 5.6% more delta-v.)
Other related posts:
