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Old 01-19-2010, 04:35 PM
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Mark II Mark II is offline
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Quote:
Originally Posted by BEC
One other comment: there are the WECO (German) motors available it its motor menu, but they're not on Thrustcurve.org. It makes me wonder where the motor data really came from.
Sorry for the delayed post -- I was scanning the forum in search of information on Openrocket when I can upon this last post. As I understand it, thrustcurve.org is a voluntary effort to provide a comprehensive sport rocketry motor reference site. The motor thrust curves are only part of it, albeit a big part. It also has very helpful search tools, simulation tools and other features. It is independent from and not affiliated with any of the rocket motor manufacturers or with any of the certification entities. Therefore although it is an enormously helpful site, it is not an "official" repository of motor data, nor is it always completely up-to-the-moment current. I don't think that the site does its own testing; instead it pulls its data from motor certification documents from the "official" motor testing organizations (NAR, TRA and CAR). Each organization tests and certifies a certain subset of the available motors, and no single motor certification committee tests all motors. (As a general rule, all motors from Estes-Cox and Quest, for example, are tested by NAR, while it appears that many, perhaps even all, of CTI's and HyperTek's motors are tested by CAR. NAR's S&T and Tripoli's TMT pretty much divvy up the rest between the two of them for testing, from what I can tell.) All three organizations have reciprocal arrangements with each other to accept the motor certifications of the other two organizations. Together, they compile a combined list of certified motors, which is updated once or twice a year, I think. All three testing committees collect data on a common set of variables, but each entity may also publish additional data on the motors it tests that may be of interest to its organization's particular membership. As a result, the cert. documents and data don't look exactly the same from each committee, but the data that is relevant for certification purposes is always there in every committee's documents.

This page at the NAR website provides a link to the CAR/NAR/TRA Certified Motor List, as well as a detailed listing of the motors that are currently certified by NAR's Standards and Testing (S&T) Committee. (The other two organizations have similar pages at their websites.) Scrolling down to the "A" motor section, you can find a listing for the Quest A8-3 motor, which is the WECO-made motor that you have, along with a convenient link to its certification document. Since your post was made so long ago, I suspect that you have by now found all of this information already, but I thought that I would add it here just in case. In all likelihood the author of Openrocket used the data from NAR's certification document to create the motor file for the Quest A8-3. (A listing of the raw data that was used to create the curve is usually included on the second page of the document, in case you want to plot your own curve. I use that data on very rare occasions to create motor definitions that aren't in my set of files for RockSim, using the EngEdit utility.)

MarkII
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