Friday, September 04, 2015

Clearing up the confusion...but not my lack of knowledge

TRF member aerosadt, an actual aerospace engineer, picked up on my Saturn V, SA-667 posts and pointed out my potential confusion between thrust augmentation and gas-dynamic stabilization. I am not confused to the extent that I know they are distinct effects. However, that doesn't mean I really understand either.  He posted a subsequent explanation of thrust augmentation and made it clear that I shouldn't expect any thrust gains. I really didn't expect any gains and should have used a name other than 'augmenter'. I had wanted to try a smaller diameter induction tube on this build and decided that the Jetex style augmenter would be as good as any (darn, there I go using that term again).

This interchange also exposes my lack of understanding about GDS. Although I generally could follow Dean Black's papers, I don't understand them well enough to translate them into design rules. (Luckily, when I adhered to Dean's latest reference design, my Inductor was successful.) So, it is entirely possible that this smaller tube won't provide any GDS. It is also possible that the...er...augmenter tube will actually be a degrader tube. In the end, this rocket should be statically stable without any GDS and hopefully there get enough airspeed for those little fins to work.