Re: Regarding Aerotech RMS motor delays

Sweet ! Hat tip to David and Gary. Quoting David quoting Bruce, this now represents a manufacturer-approved modification to shorten delay times and is legal to use on RMS from RCS and AT at NAR-sponsored launches, no ?

Next question...will Dr. Rocket need to publish similar instructions (if he so chooses) for use with his cases ? Unless and until the good Dr. does so, drilling one of his delay grains remains beyond the pale according to the Safety Code, yes ?

John

Nope. The cases are the same (for cert purposes). It's the propellant and delay that affects it. In this case just the delay.

I told you so.

Over and over.

Maybe in another 6 years or so he will adopt yet another proposal I made.

Jerry

GFL

It is reload manufacturer specific.

Gary did not do this for you.

He did it for his customers.

Dr Rocket only makes hardware. All the reloads are made by Aerotech.

Is the AT adjustment release going to be publicly posted somewhere?

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

I'd sure wait for a call from S&T and TMT on this one. (not Bunny, but S&T)

If you read the post from CTI on their adjustment tool, seems there was a cert impact. We're only hearing from Gary, formerly of AT, now of RCS, that it's ok....

Gary got away with the Ellis j350 thing without a recert, but that may have been the last of his chits. The user mod there was to drill out the core of the grain, as the motor was made in different environmental conditions (NV vs. Texas). That was cato city for a few months, and the motors should have been recalled.

Remember folks, a delay is only certified to be +/- 20%, so a 10 sec delay might be only 8 sec without any modification, so if you drill out 2 more seconds, it could be a 6!

If you want a "true" delay" use electronics! Don't use an inaccurate method to mod an inaccurate delay time!

Phil won't like this, but I'll say that using electronics is a valid way to adjust the bird's motor delay! "adjust the bird and not the motor"

Certainly true, and that make the modification of the delay useless...

Wonderful. So now we are allowed to drill the combustion chamber end of the delay by the same amount even if the propellant and/or thrust curve is not the same. I thought from the discussions here that the combustion of the delay while the motor is under pressure was faster. If the motor burns longer, the delay is exposed longer, and 1/32' is not the same amount of time under pressure or after burn out. It was also often said that modification of the delay couldn't be easily done because of that point.

But maybe that this is not very important since delays can be +/- 20% of the spec. Drilling to remove one or two second is nearly useless on a 10 seconds delay... (that makes a 8 to 12 seconds delay a 6 to 10 seconds one)

"Bruce Sexton" a écrit dans le message de news: snipped-for-privacy@f14g2000cwb.googlegroups.com...

I have no problem with that and don't really consider it to be adjusting the bird. As you said if you want accurancy, use electronics.

Even if you drill on the combustion end the overall length is being reduced by X/32" and that reduces the time it takes to get to the other end by a linear amount. While the delay burns at irregular rates during burn, it does that on any delay length about the same amount. So the OAL modifies the final delay time since the post burnout delay does burn linearly since it is burning at ambiernt pressure.

All of these are "Kline delays".

Jerry

Or it could be a 12 and you've now made it a 10. Adjustable delay or not, that's why it's critical that TMT stop hiding the results of the delay tests they perform. Even without the just announced delay mods, there are probably MANY cases where a user could make a better selection if htey had the actual test data instead of trusting that S M L is 6 10 14 and totally infallable.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

One more time. It doesn't matter which side you drill. Delay time is a function of the total thickness.

Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!

And, once again, I point out that this entire discussion took place regarding NAR acceptance of delay modification on the AeroTech reloadable motors. If you want to extrapolate it to TRA, go right ahead

-- but neither you nor I are a member of the organization.

David Erbas-White

Heretic!

Burn him at the stake!

Use a USR 54mm M motor!

Jerry

-----snip-----

Which underscores my thesis that motor testing and certification should be independent of the national organizations. The manufacturer's submit their products for testing and the results are posted in a central repository.

Then an organization can decide, according to its own agenda, whether or not to authorize use of the product(s) at launches they sponsor. It would be the responsibility of the members of the organization to decide as a group what principles their authorizations should adhere to.

No muss, no fuss, no hidden data. No need to be concerned about relying on another organization's test results because everybody would be using the same data set.

John

To be effective you would still need a "treaty" between the existing orgs if you wanted cross-certification pending the day your efforts took over certs entirely since they are better and more accesable.

allegedly.

There is every indication that existing orgs are open to such treaties.

In fact, given the widely publicized limitations of the Tripoli cert efforts in particular, it seems they have very low standards for treaty now.

Yea team.

There's barely enough 'work' out there for this to take place on a 'volunteer' basis. So, who's going to pony up to make this a 'business'? Anyone? Anyone? Bueller?

The system 'works', such as it is. If people become angry enough at any perceived problems with any of the organizations, they will either a) work to change the organization, b) form their own organization (as you suggest), or c) work to make the organization irrelevant.

While I understand your desire to have this 'perfect world' scenario, this isn't a 'perfect world', and we all work to get the most out of life with the least expenditure of resources. IMHO, the least number of resources are expended by trying to work with the existing organizations to get any needed changes in place -- while understanding that working with volunteer organizations is a whole different beast than working with an organization that you are paying (and that is dependent upon your money).

David Erbas-White