That seems reasonable to me. For my 250 lbf 250 psia LOX/Kerosene
engine, I used an L* of 40. The throat diameter was 0.94 inches, the
contraction ration was 8, and the chamber length was 4.2 inches. Note
that I monkeyed around with the numbers to get something that I thought
I could build on my existing equipment. For example, I didn't feel
comfortable drilling the cooling holes much more than 4 inches deep.
And I wanted the OD of the engine (including the injector flange) to be
less than 5 inches.
-Bob
On 11/10/2016 08:41 PM, Graham Sortino (Redacted sender gnsortino for
DMARC) wrote:
Hi All -
I’m in the early stages of designing a 500 lbf 350 psia LOX/Kerosene engine with a 1.1 inch throat diameter and I was wondering if I could quickly check my math regarding L*and chamber/throat contraction ratios.
From reviewing H&H, it seems to suggest that an appropriate L* value is in the range of 40 to 50 inches for this propellant combination (table 4-1). Further it goes on to say that for an approximately 1 inch throat diameter the contraction ratio is roughly 5.5 and the chamber length is slightly below 5 inches (from fig 4-9 and 4-10 respectively).
Since I suspect that this is a similarly sized engine to those others have built I wanted to check quickly to see if others have had good experience with those numbers?
Please feel free to ask any additional clarifying questions.
Thanks as Always,
Graham
