On Sat, 13 Sep 2003, Ian Woollard wrote:
> I don't know, why not just borrow a trashy, leaky, creaky, junked jet
> engine that just about runs, but is no longer flight worthy from
> somewhere. Point at ramjet. Do tests. It doesn't have to be a perfect
> test, just good enough that your flight testing has a reasonable chance
> of lighting and staying lit. Sell jet engine and make up a batch of
> cheapo ramjets for flight testing.
Now, add in the rent for the aircraft used for flight testing. That's
actually more expensive, per test hour, than the combustion wind tunnel.
Which is why people build the tunnels.
There just ain't no cheap way to *fully* test and *operationally qualify*
a ramjet. It's not enough if it sort of works; if you're trusting it to
get expensive hardware back from far offshore, you've got to know things
like how it behaves in off-nominal conditions. The way you define its
operating envelope is to test it over a still larger envelope.
It's very easy for rocket people to underestimate the effort and cost of
properly testing a jet engine. Rockets are easier to test because they
are less sensitive to outside conditions, and traditional rocket test
programs don't aspire to anywhere near the level of reliability assurance
considered necessary for aircraft.
Henry Spencer
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