>> I finally got my ALTS25 and Olsen altimeters in the same rocket
>> at the same time. The Olsen was just along for the ride this time.
>> In the near future each will be connected to a separate electric
>> match in the drogue and main ejection charges (two matches per
>> charge) for a ride to 7,000'.
>> I didn't record the altitude numbers in the field, but I recall them
>> being 2406' for the Adept and 2396' for the Olsen. That's close
>> enough for me. I just want the drogue and main to deploy at
>> the right time. I like both units.
>That's relative (and, apparently, very subjective). Give me *numbers*.
>IOW, you've told us nothing.
>Now, Dean, I'm not saying that the 'two' altimeters are not workable in
>this application (i.e. rocket recovery) -- but one thing that a lot of
>people fail to understand is the *DYNAMIC* nature of recovery and the
>fact that properties of materials measured in a *STATIC* environment
>does not tell you everything about what it'll do dynamically.
>in particular, can undergo flight failure (just like concrete will) in
>a shock loading situation. Olsen is a REAL GOOD altimeter in cases
>stressing past the yield point could happen - even if the onset of the
>Give us numbers. Don't 'hype' us. Then we can see.... clearly. You'll
>look a lot more credible that way.
>uhhnnnnn, ymmm, gooooo, Huh! What? Oh...sorry, I was having a
Ha ha, cute. You get points for satire.
I started reading the above, and was thinking "Ah, what, umm, this
doesn't make sense... Oh! Cute."
BTW, as someone relatively new to this area, who has no political ax
to grind, who hasn't met any of the players, I want to mention that
I think Mr. Cato was in the right when he questioned the plastic
snaprings. As someone with an engineering background, I have to agree
that the pull-with-the-pickup-truck tests did not test dynamic loading
and possibility of brittle failure. The advantage of metal, and aluminum
in particular, is that it is ductile and posseses "toughness". Plastic
can be made "hard", and somewhat "tough", but it's characteristics
can never be the same as metal. The pickup truck tests just wern't
very useful from an engineering standpoint. They fall more into the
gee-whiz catagory of things that are more useful to marketing types.
The loads imposed from a rocket flight are completely different than
the loads that were imposed by their tests. I would have prefered that
they put a 1' piece of webbing over a ceiling beam, then the snaplink,
then enough webbing attached to a concrete block, such that the block
would stop and be suspended 2 feet above a floor. Take the block up to
the ceiling, drop it, and then see how the link held up. Better test.
What I *did* find much more compelling than their tests, was the simple
fact that the rings are man-rated for emergency use, which means they've
gone through a great deal of testing and certification to reach that
point. *That* is useful information. The pickup-truck-test, OTOH is
just so much hype.
My experience has taught me to cast a skeptical eye on manufacturer's
claims and their testing methods. Very often, they are gee-whiz dog
and pony shows meant to impress the heck out of the customer, but on
closer inspection are devoid of any real substance. I suspect that
Mr. Cato has similar background. I did not view his challenge as an
attack, just someone asking valid engineering questions.
I'm probably going to be sorry I waded into this, but This whole subject
bugged the heck out of me when it first happened. I elected to stay out
of it that time, But Since you decided to bring it up again, I decided
that it was necasary to add an unbiased view to this issue.
gregc <at> pm-tech [dot] com