[AR] Re: Issues with operating at low chamber pressure
- From: Lars Osborne <lars.osborne@xxxxxxxxx>
- To: arocket@xxxxxxxxxxxxx
- Date: Fri, 2 Sep 2016 18:01:20 -0700
I am not going to have tanks be load bearing for obvious reasons
Why? load-bearing tanks are very common. Being pressurized will increase
stiffness, and resistance to buckling.
Thanks,
Lars Osborne
On Fri, Sep 2, 2016 at 4:02 PM, Zachary Martinez <znm3m8@xxxxxxx> wrote:
Sent from my iPhone
On Sep 2, 2016, at 16:41, George William Herbert <george.herbert@xxxxxxxxx>
wrote:
Bill is correct, but you get very fragile rockets and minimum gauge
problems this way.
Not impossible, just... Be careful.
I am not going to have tanks be load bearing for obvious reasons, but I
will still have to check to make sure I still have a decent factor of
safety against buckling during expected g loading. Using aluminum rather
than stainless should help as it increases the wall thickness.
Sent from my iPhone
On Sep 2, 2016, at 12:04 PM, William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
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
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