[AR] Re: Closing the loop on rocket engines
- From: Ben Brockert <wikkit@xxxxxxxxx>
- To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
- Date: Wed, 9 Dec 2015 23:01:16 -0500
On Wed, Dec 9, 2015 at 10:12 PM, Wyatt Rehder <wyatt.rehder@xxxxxxxxx> wrote:
You can characterize your mixture ratio pretty accurately on the ground, and
have a pretty solid expectation that it is going to be the same in flight.
Main reason this works is again you have a high level of control over your
propellants.
So liquid engines have been doing closed loop control for quite awhile.
These statements are contradictory. Expecting high levels of
characterization from ground testing to be sufficient knowledge for
control is the basis for open loop control. Measuring and responding
to what's going on in flight is closed loop control.
Closed loop control over every variable of significance is required
for high performance. For a liquid rocket, those variables are, at
minimum, thrust, attitude, and mixture ratio.
Using car oxygen sensors in a rocket engine is still an obviously bad
idea though.
Ben
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