guest blogger john hare
The friends I know in the rocket industry are too busy running businesses and fulfilling contracts to work cheap or free on the unproven concepts that I find interesting. It has come to my attention that there are a lot of other groups out there doing rockets that can use even very small amounts of money to move their projects forward. For them to go after it, those small amounts of money would have to be attached to something simple, interesting, in line with their current projects, and with the potential for much higher returns on their time.
We may have a common ground for some projects. I have suggested all sorts of wild ideas in the interest of serious fun. If they work, I am serious, if not it was just in fun. 🙂 A few of the concepts didn’t get busted and have serious profit potential. The compensating nozzles in particular address an issue that has been neglected for development in this field. I want to throw out the simplest one I had to see if anyone would find it worth fooling with.
The boot compensating nozzle idea could be tested without destroying the hardware that cost so much time and money. The concept is that an over expanded nozzle has an external subsonic inlet attached to half the perimeter. When the flow is trying to separate at low altitude, the inlet smooths the way for air to flow into half the nozzle to fill the bell so that the main exhaust has full expansion for that chamber pressure and altitude.
The economic reason for exploring this concept is that it can be tested with available engines and launch vehicles. Down to the HPR and Tripoli launches if the test stand results are positive. Most other compensating nozzles are just too expensive to test. Too expensive to test means they stay on the wish list indefinitely, as in aerospike. The NGLLC competitors could certainly have used some compensating nozzles for their flights this month. It wouldn’t hurt the Lynx or Falcons either if it could be proven quickly and inexpensively.
A subsonic inlet in this case is made from a piece of pipe or tubing laying around as scrap. Material properties of the material are unimportant as long as it can stand a few second characteristics burn before melting. The important thing is that it create a situation in which atmospheric air preferentially enters the nozzle to separate the rocket flow in exactly the manner intended. Look at airliner jet inlets for what I have in mind. Ideally you would have half of one of them instead of dumpster stock, but this will be a cheap contest if it happens at all.
If the offer was for the first data set that compared the same over expanded nozzle unmodified and modified in two runs, how much would it take? Results with pictures on your website with no travel or hardware sent. How would it be verified that the test took place? How would you know that I would or could pay up? Is there an organization interested in handling contests for stuff this small that can be trusted? and so on.
I am looking for real world ways of confirming or busting some of my concepts within my budget. Would $250.00 get some interest, or would it take $1,000.00 or $10,000.00? One I could do next week, one in a month or two if nothing goes wrong, and one never. I’m looking for feedback on if this series can and should be started.