Zachary:
You can do as little as 50 psia against vacuum and 150 psia to sea level
air; look into Bob Truax's Sea Dragon work for reference.
That said, note that he was planning on using Lox / LH2 to recover the lost
Isp. But as a general rule mass fraction improves as the operating
pressure of a pressure fed liquid drops...and mass fraction has an
exponential effect on performance, whilst Isp is merely linear.
Bill
On Friday, September 2, 2016, Zachary Martinez <znm3m8@xxxxxxx> wrote:
Hello all,
Are there any issues operating at a relatively low chamber pressure for an
engine ~180-220psi other than the poor Isp. For a pressure fed rocket with
a relatively high thrust to weight ratio the benefits of using a lower
chamber pressure are really tempting, but I imagine there are some design
challenges that I am unaware of. My main concerns are difficult ignition or
possible flame out but I don't really know.
Thank you,
Zachary Martinez
Aerospace Engineering | Missouri S&T
