A quick question! What is the shelf life of Estes rocket engines? Can they
NOT be safely flown after a certain number of years?
The shelf life depends on how they were shipped and stored. The larger
diameter engines are more prone to failure from heat cycling problems
than the smaller ones.
If any engine is shipped or stored incorrectly, it may be no good by
the time you buy it - although this is probably very rare. If you do
not store the engine right, it could also ruin the engine, before you
get a chance to use it.
With proper storage, the engines should last indefinitely. Both C.D.
and I have engines from the 60s that still work fine.
If you've stored the engines (woosh generators) under favorable conditions,
they can last a long, long time. I've had no problems with 20 year old engines,
and problems with ones right from the store. It depends on how they've been
Thermal cycling, such as we get from the seasons, is bad. The propellant
grain expands when it's hot, then contracts when it's cold, moreso than the
casing. (There is a difference in the coefficients of thermal expansion, in
other words.) If this happens enough times (sometimes once is enough), the
grain separates from the casing, providing a nice extra "port", resulting
in a spectacular pyrotechnic display ("cato").
Humidity is another villan. It causes nozzles to soften, which is bad.
In general, if you've treated the engines as if they were very picky human
beings, at least with regard to their storage enviroment, keeping the
temperature between 18 and 22 degrees Celsius, or thereabouts, and the
relative humidity below 60 percent, they should do very nicely. But when
taking a pack of those old Prodynes out of the time capsule, make sure
to static test one or two, just to make sure.