In any case, when you're trying to evenly deplete propellant in the
tanks, the most direct measurement is of the propellant levels in the
tanks. Other measurements are more indirect; flows, for instance,
have to be integrated and then the results subtracted from the initial
propellant loads, which introduces more places where errors can enter
into the calculation.
On Thu, Dec 10, 2015 at 01:49:38PM -0800, George Herbert wrote:
One advantage of low density propellants is that a slight excess of the
lighter one and burning the heavier one to depletion is a good strategy when
you have a bit of uncertainty.
George William Herbert
Sent from my iPhone
On Dec 10, 2015, at 6:57 AM, Paul Breed <paul@xxxxxxxxxx> wrote:
Getting simultaneous propellant depletion at clost to optimum ISP is what
matters.... it does not matter if the earlier part of the burn might be
slightly off on O:F the steep part of the curve is at the end.
On Wed, Dec 9, 2015 at 9:21 PM, David Weinshenker <daze39@xxxxxxxxxxxxx>
wrote:
On 12/09/2015 08:59 PM, Monroe L. King Jr. wrote:
I'm not suggesting using car O2 sensors I know they wont work. I'm
looking for something that will work.
Those optical sensors are not the same as O2 sensors.
Engine management in cars is what I know I am speaking generally in that
direction based on what I know about that.
I see plenty of reasons to want better control over the engine.
Yes, mixture control is a good reason.
A valve can be controlled, pressure/rpm of the power turbine and many
other factors.
If you want to do closed-loop control of rocket O/F ratio, there may be
usable methods other than direct flame-chemistry sensing - e.g., using
the pressure drops across the injectors as a proxy for flow measurement,
and then "closing the loop" to maintain a desired relationship between
those signals.
-dave w