Hi TRF colleagues,
Over the last several hours, I have conducted many OpenRocket tests using the base-drag hack. (To a lesser extent, I have also been testing this issue with RockSim.)
For sure, when you have a short, wide rocket — a rocket whose length measures much less than 10 times its diameter — the base-drag hack yields significantly different results, and presumably of course those results indicate the rocket’s stability more accurately.
So far, so good.
But why stop with short, wide rockets? Perhaps applying the base-drag hack improves the stability accuracy results of any rocket. I can say that the wider the rocket is compared to its length the more the base-drag hack affects the stability reading. However, I have now determined that applying the hack to even a long, narrow rocket yields different results, although the results deviate proportionally less than they do for a short, wide rocket.
Incidentally, I understand that a rocket having a tail cone provides an exception. For example, applying the hack to the V2 would yield incorrect results, unless you truncate the aft cone used in the hack. (See Peak of Flight newsletter, Issue 157 [14 Mar 2006], pages 3–4.)
Bottom line: I thnk that I am suggesting to always use the hack. I suppose that one could counter the argument by saying that doing so would be more trouble than it’s worth.
Anyway, just a thought.
Thank you.
Stanley
Over the last several hours, I have conducted many OpenRocket tests using the base-drag hack. (To a lesser extent, I have also been testing this issue with RockSim.)
For sure, when you have a short, wide rocket — a rocket whose length measures much less than 10 times its diameter — the base-drag hack yields significantly different results, and presumably of course those results indicate the rocket’s stability more accurately.
So far, so good.
But why stop with short, wide rockets? Perhaps applying the base-drag hack improves the stability accuracy results of any rocket. I can say that the wider the rocket is compared to its length the more the base-drag hack affects the stability reading. However, I have now determined that applying the hack to even a long, narrow rocket yields different results, although the results deviate proportionally less than they do for a short, wide rocket.
Incidentally, I understand that a rocket having a tail cone provides an exception. For example, applying the hack to the V2 would yield incorrect results, unless you truncate the aft cone used in the hack. (See Peak of Flight newsletter, Issue 157 [14 Mar 2006], pages 3–4.)
Bottom line: I thnk that I am suggesting to always use the hack. I suppose that one could counter the argument by saying that doing so would be more trouble than it’s worth.
Anyway, just a thought.
Thank you.
Stanley