Cheap Contest II

guest blogger john hare

I did a resin cast nozzle with embedded string today to observe the effects as an air tank blew down. My intent was to start with a nozzle almost at separation and then add a boot to observe the flow patterns. Since the nozzle was slightly asymmetric and had excessive expansion, it had  separated flow from the start. Access to higher pressure air might cure this. Anyhow, it started with one string being sucked toward the throat, then two, then three of four. Since this was the result I wanted from the boot device, I think it somewhat more likely that the thing will work on a nozzle at or beyond the point of normal separation. My theory is that separation under control is a good thing.

 Since I don’t have the minimums suggested in ready cash, I will offer a smaller amount just in case someone is still interested. If not, I can increase it later when I have sufficient uncommitted green. Please don’t take this as not respecting the information, just as an indication of impatience and cash shortage.

$350.00 to the first published static test results of the boot compensating* device on an over-expanded rocket engine compared to the same engine operated in the same conditions without the device.

Test equipment must be capable of recording measured results, good, bad, or indifferent  in a way that is generally understood by the readers of this blog. Short duration characteristics burns are probably sufficient.

Since I am obviously prejudiced by this being my idea and money, however small, judges of whether it was a valid test are the regular commenter’s  here. We want side by side thrust data at the same chamber pressure or propellant flow rate.

These rules change if someone brings up a valid reason, which is likely considering that I have never written contest rules and frequently am unclear in my explanations.


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I do construction for a living and aerospace as an occasional hobby. I am an inventor and a bit of an entrepreneur. I've been self employed since the 1980s and working in concrete since the 1970s. When I grow up, I want to work with rockets and spacecraft. I did a stupid rocket trick a few decades back and decided not to try another hot fire without adult supervision. Haven't located much of that as we are all big kids when working with our passions.

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One Response to Cheap Contest II

  1. john hare says:

    I can now offer $500.00 for the first results.

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