[F-FT] Regarding Aerotech RMS motor delays

TY David!

WooHoo ! Way to go David ! Let me see if I understand correctly...if the manufacturer releases instructions on how to safely modify the delay grain in their reload kits, NAR won't require recertification of the motor ?

We might well be on a cusp here...I know Anthony Cesaroni and Mike Dennett of CTI are following this thread. Perhaps they could be persuaded to issue similar instructions that specify how to shorten the delay time by drilling X inches per second of delay reduction ?

Can somebody who knows the right names pulse TRA and CAR to see if they are in nominal agreement with the concept that doing a modification to the delay grain to adjust the ejection time does NOT invalidate the existing certification of the reload kit if the manufacturer provides instruction on how to safely make the modification ?

John

That's basicly what I said earlier in this thread. The ball is in the manufacturer's court. The score is already CTI - 1, Aerotech - 0, but Gary seems to be lining up a shot right now.

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

You seem to care about it and know how to write so...

That is MY understanding, but we'll have to wait for the actual press release to see the full ramifications. The commentary from the NAR was that a "manufacturer must endorse" any modification practices. BTW, this is my understanding of how it has been for quite some time, but I guess it never reached the 'critical mass' necessary for Aerotech to actually 'endorse' this. And I can understand how busy they've been since the fire. But this appears to be something that needs to be done, and it appears that they're doing it.

I'm quite happy with how things are moving along. And thanks to everyone for participating in the thread.

David Erbas-White

One might note I have been saying this consistently for years with SPECIFIC proposals for Aerotech to adopt.

Glad Mark Bundick is on board :)

Gee, glad you were far more effective than I.

G O D B L E S S ! !

David Erbas-White rocks!

Point!

Knowing Gary, probably as a direct result.

Point !!!!!!

Correct. Intended use.

It is a NFPA-1125 provision which is a "North America" thing.

Jerry

Yes, especially David and John.

CTI has a several year head start.

If only USR had developed the technology, then everyone whould have stolen it by now :-)

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

It is not a lead-time technology, only a political problem at NAR/TRA.

It did and they were prevented from stealing by arbitrary TRA/NAR rules.

But for the time you still could get USR motors, fully adjustable delays were the norm.

Jerry

You missed the rant last month where it was claimed that everyone that had reloads stole the design from Kosdon. Guess Jerry doesn't have a lock on that type of claim.

Sorry for being a little more negative about this. There are things I don't well understand. I thought that the certification process was intended to confirm that a motor behave as predicted by the manufacturer (the fact that the results of the tests often give numbers that differ from those originally issued by the manufacturer is already disturbing, but that's another story). So I thought that the delay also was certified. That, if the manufacturer say: "this is a 4 second delay", it is tested to see if it is conform to the spec. Because, if the rockeeter uses a 4 second delay and that the real delay is 10 second, the rocket will crash on the ground without deploying anything. So if the delay modification method is endorsed by a manufacturer, I suppose that this fact and the method must also be tested and certified.

If all the above is not the case, then what is certified when I buy a D12-3? Does the organisations only measure the thrust curve? Or are all the available delays tested and approved? And in this case, what is the tolerance?

Would it be acceptable to have motors with "uncertain delays"? Is that acceptable that a rockeeter present a rocket to the RSO saying: "this is a 6 second delay, modified to be a 3 seconds delay"? Will the rso open the motor to check the fact? If the rocket crash then opens the parachute on the ground, is that an error from the rocketeer, did he lie, or was it a malfunction of the motor?

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A D12-3 is a single-use motor. It is NOT adjustable. There is no intent to make any single-use motors adjustable (to the best of my knowledge).

The available 'stock' delays are tested and approved. This assures all concerned that a specific delay grain will actually burn for that amount of time. If the manufacturer endorses a method of modifying them, then it means that you have the OPTION of modifying them by that amount. The certification process assures that the base material that you work with has a specific value. If a delay grain was certified as 4 seconds but was actually 7 seconds, that would be a problem -- but the certification process assures that if a grain is claimed as 4 seconds, it really is 4 seconds.

There is no need for the RSO to check that 'fact'. The RSO does not currently disassemble your assembled reload to assure that you did it correctly -- the other aspects of the safety code ensure that IF someone makes a mistake, that there are no injuries.

It is ALWAYS the rocketeers fault, unless the delay doesn't ignite, or burns out prematurely. There are so many other things that can cause a failure that it isn't even funny that you would 'focus' on this issue. Furthermore, the only ones who will realistically attempt delay modification are those who believe it is truly necessary. If you launch a rocket with the recommended reload two or three times, and each time the delay is one or two seconds two long, you'll want to adjust it down by a couple of seconds. This is what experience brings -- but up until this point, modifying the motor in such a fashion would be 'illegal', even though it will make for a SAFER launch.

David Erbas-White

Most of that is how you define "burn time". A typical c-slot or moonburner motor has a long tail-off.

Do you use when thrust drops to 0.000 pounds?

Do you use the military method and disregard anything below 1/10 of peak thrust?

Do you use the NAR method that only truncates the amount under 5% of peak?

Do you even bother or do you submit it and "hope for the best"?

It also allows a consumer to overcome consistently wrong delays as delivered by the manufacturer (to the lower side).

All.

Yes there is. All CERTIFIED USR motors were recommended for delay mod by the user.

Tripoli does not list them, so that is not assured. NAR does.

Correct. This is the central point of this discussion.

IF it is even tested and published.

To the best of my knowledge there are no currently certified motors on the NAR list. The basis of this discussion is regarding NAR allowing use of delay modifications on reloadable motors on currently certified motors. Also, before this degenerates further, I politely asked at the beginning that this be kept a flame-free thread.

This discussion was not about Tripoli, it was about NAR. And again, please refrain from having this become a 'bashing' session or thread. The intent of the thread is solely to discuss the upcoming possibility of NAR recognizing delay modifications to Aerotech reloadable motors.

I 'assume' that because of cross certifications, that TRA would 'recognize' this if/when the manufacturer endorses it, as NAR has already said is the only thing that is needed.

Again, NAR does this, and this entire thread was established relating to a discussion between myself (as an end-user and NAR member), Mark Bundick (representing NAR), and Gary Rosenfield (representing AeroTech). At no point in this thread, or in any other of my comments, has there been any mention of TRA, and whether or not they can/should publish their data on their website. And again, this is meant to be a flame-free thread, and was not started to facilitate anyone 'bashing' anyone else.

I REALLY, REALLY would appreciate it if folks would 'honor' flame-free thread designations -- that includes both those who try to initially divert threads (as has been done here, several times, by the same individual), and by those who will now want to tag on with "See what he did???"

David Erbas-White

-----snip-----

Certainly not on my part. Single use MR motors should not be adjusted because they aren't designed for flyers to be messing around with their innards. I am only advocating legalizing delay time adjustment by drilling in accordance with the manufacturer's instructions once such instructions are published by the companies who make the reloadable motors.

And, thanks to David's quick legwork it appears that such modification instructions will be forthcoming from RCS for their reload kits. Hopefully (in my case, very hopefully) CTI will quickly follow suite and release Pro38 modification instructions in time for me to use them in July.

In a different thread on this subject I gathered the impression that the DAT tool itself probably won't be changed because the tooling costs involved would be prohibitive.

John

I took a D12-3 as an example. Bad example, I know. Replace "D12-3" in my original post with "D13-4".

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