From it's introduction in the 1973 catalog, Centuri claimed "Out of sight with a C". From 1974 through 1978, the Screaming Eagle could reach 1,500 feet. From 1979 on it lost 300' altitude, down to 1,200 feet.
Here's even more altitude estimations from the Screaming Eagle kit instruction sheet:
On the same rocket, altitudes predictions changed over time. There wasn't much consistency.
I remember seeing my first Estes catalog and thinking: "A 50 cent rocket can get to 2,000 feet?"
How could they know? There were no small altimeters then. And who could or would challenge the claims?
They probably "guess-timated" using the Altitude Prediction Charts, the old Estes TR-10.
Makes me wonder if any of the R&D staff at Estes/Centuri ever parformed visual altitude measurements on kit models using tracking scopes.
ReplyDeleteHi Ed,
DeleteI'm sure Estes used their Altiscope and Centuri used their Sky Trak. These protractor based trackers weren't very accurate, getting a reading with my Estes Altiscope was iffy.
The whole purpose of this post was to show how altitude estimates changed over the years.
I'd hazard to guess that the altitude estimates come from applying some basic formulas that take into account weight of model and total impulse of motors, with perhaps a "guesstimate" of the effects of drag.
ReplyDeleteYou can refine the predictions through results from test launch with actual launches of some models using the visual tracking methods (typically described in model rocketry manuals). Perhaps not a not a "dead nuts" value, but something that's good enough.
ReplyDeleteHi Naoto,
DeleteYou would have to do a few launches with a protractor /scope and take an average. As I wrote above, "The whole purpose of this post was to show how altitude estimates changed over the years." The earliest catalogs had some pretty high estimates. These were toned back as the years passed.
Most of them are still a bit optimistic. John Boren says that the recent ones are from RockSim.
ReplyDeleteI find it also amusing how the estimates for a given model have varied back and forth over the years. The Alpha has had anywhere from 1000 to 1500 feet called out...and it's pushing to get it to 1000 feet on an Estes C6 (this measured by FireFly or FS Mini along for the ride). Some models are further off than others, of course....
A Streak on a C6-7 to 2000 feet? Maybe....but you'd never know it.
My thoughts exactly!
Delete