Max weight on a Pro38 G69...?

I will look at in in the context of Jerry's observation and revise it

it's good to be here :)

- iz

shockwaveriderz wrote:

Hey! At least it is a multi-dimensional analysis.

just don't make them on ROL, or TRA list, right? :(

- iz

in principal

in fact, the 133G69 tests out at 128.8 NS total over a 1.93 second burn time.

the designations are not always representative of the tested performance

I know this is common among manufactured motors, but don't know the background on why it should be so common. Is the designation a nominal impulse during an earlier test by the manufacturer, and the certification samples varied in composition or construction? How consistent is performance within a batch, and between batches?

NFPA 1122 specifies tolerances for variation as follows

=== NFPA 1122, 2001 Ed. (excerpted for editorial review)

(1) Static testing, conducted at or corrected to sea level and 20°C ±

(a) Standard deviation of the total impulse data shall be no greater than 6.7 percent of the mean measured value.

(b) No time delay shall be measured to have a variation greater than 1 second or 20 percent (whichever is greater, but not to exceed 3 seconds) from the labeled value.

(c) Imprinted average thrust shall be within 20 percent (or 10 N, whichever is greater) of the average thrust that is computed by dividing the mean total impulse measured during propellant burn time by the mean propellant burn time. ===

to see caculated average thrusts based on reported total impulse and burn time as tested by CAR, TRA or manufacturers performance data (in that order of precedence), see the Pro-XX motor reference I compiled on

(all max launch weights are based > I have been used as a "consultant" to generate MLOW tables for several manufacturers (AT, USR, IBCo, CD, RDS, others). It is a judgement call, but here are my GENERAL criteria: >

:)

- iz

Yes.

Few manufacturers take the time to do delays right and actually meet this spec in practice. Hence "bonus delays".

The dead-on designations were assigned FROM THE TEST DATA. We have seen in another thread that the thrust curves done by Aerotech for TRA and by TRA TMT later using cloned equipment both have severe noise and instabilities in them.

Makes for variances from other test equipment that does not have those inappropriate issues.

Glad to help.

On 11 Jan 2004 09:56:07 GMT, snipped-for-privacy@aol.com (RayDunakin) wrote:

Thank you for answering my question. Is this instead of the model rocket rule that limits liftoff weight to that recommended by the manufacturer, or does 4.9.1 only provide a maximum limit that a HPR motor manufacturer can recommend?

Alan

Ah, so when I refer to Moe, Larry, and Curly setting a Manufacturers Maximum Recommended Lift Off Weight, I'm probaly refering to Jerry.

That is not very technicaly satisfying, but at least we know your methodology.

Alan

Yep.

Welcome to the kludge.

it is the maximum liftoff weight that can be permitted to launch by the RSO at a high power launch

- iz

This is a perfect example of a well intentioned rule which is NOT enforced at the field at most launches. It simply is NOT a safety issue to have an OVERWEIGHT rocket.

Jerry

hey, it was Bob's shortcut, but I believe it was oz

besides, the K1050 isn't a CTI motor, so I wouldn't know ;)

- iz

How about slugs and poundals? I do all of my calculations in slugs so forces are in pounds force. It drives the chemists I work with nuts to see a slug-mol. There is alot of undue confusion about the difference between force and mass.

Almost all units are arbitrary at some level. Like the meter - it was originally defined as 1/10,000,000 of the distance on the Earth's surface between the equator and the pole. Small problem - no one knew exactly how long that was at the time. And what good is a unit of length that doesn't have an accesible standard? Personally, I always have a couple of feet with me (so far).

Brad Hitch

No. You implied that Jerry is being barred from making technical posts on those other forums, and that others are to blame for this. He is being barred for other reasons. If he had stuck to making technical posts, he would never have been barred. He alone is responsible for his actions and the results of his actions.

Never disagree on principal and testimony with the sysop or moderator?

The guy who AUTHORED the ROL Jerry-page.

Just for the record.

Jerry