[F-FT] RMS delay question/comment

-----snip-----

-----snip-----

The motor testing protocols now in place were developed when we were entirely dependent on the accuracy of the manufacturer's delay to safely recover our rockets. Thusly, it was entirely correct to test and verify that a 3 second delay is in fact 3 seconds. Longer than expected delays are bad, and shorter than nominal can be much worse. Testing and certification provided an independent check on delay accuracy. For motors where the delay composition is inaccessable, like an Estes BP the independent testion should continue.

However, there is a whole new class of motors available to us today. Reloadable designs *do* allow access to the delay element and can easily be modified with a simple twist drill. More high-tech approaches use an adjustable jig to repeatably drill the delay to the same depth.

But, we place an artificial (and unnecessary) restriction on ourself if we limit our ability to shorten delay times to only a few discrete quanta that mimic the delay steps which have historically been avaliable from the manufactures.

Specific example: the 5.5x Streak I am currently building for my Level-1 certification sims consistently with an apogee at eleven seconds. Without any modification the stock 13 second delay from the Pro38 I will be using is much too long, and the rocket is subjected to needless stress when ejection comes that long after apogee. Likewise, the next step on the DAT is 10 seconds, and the ejection charge goes off while the rocket is still going up, and I'd just be asking for a zipper. Nope, I need a delay of 11 seconds (trusting RockSim here pending flight tests).

Let's loop on this for a few iterations. An analgous situation exists in the FF airplane community regarding DT time. It is purely up to the discretion of the flyer what fuse length or timer setting to use to maximize the chance of maxing out, and still recover the model.

Shouldn't the HPR community have the same discretion ? We're not talking about somebody just starting out following an impulsive purchase at Wally-World. Someone going for HPR certification should know, and be able to hold a technical discussion about, the factors involved in making an informed delay time selection.

Relative to the testing and certification process, I would recommend the following change to the extant methodology; test the manufacturer's delay adjustment method (whether through the use of a jig or a simple depth to drill) to see if that process does produce accurate, repeatable variable time delays. The testing would thusly certify that the manufacturer's procedure consistently produces reliable delay times. Exactly what time delay to select should be up to the discretion of the flyer based on factors like specific rocket design considerations and flight weather conditions.

John

Once again, you prove yourself an ass. The facts are the facts, and you can't change them by ignoring them, pretending they don't exist, or claiming that anyone who reports the truth is somehow in support of the ATF's position.

propellant

propellant

Washington office

propulsion

(club,

openly

Not as long as the ATF has power to fine manufacturers and vendors, or even shut them down. One would think that a person who has already been fined $40k by DOT for "openly and agressively" practicing his own interpretation of the regs would know better by now.

It's very simple. Get the manufacturer to document the procedure in a manner that can be done safely and accurately by the consumer, and submit the motors and the process for testing. CTI did so. AT or any one else could do so if they choose to. But as long as AT says NO, then to modify the delay is to use it in a manner not recommended by the manufacturer, and a violation of the safety code.

The ball is in the manufacturers court.

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

Alas, all of us rocketeers were so wound up over the fee increase in this NPRM that we completely failed to notice this change to the exemption. Which may have been a good thing. If we did comment on it, the BATFE may have put their desired 62.5 gram limit into the final rule in 1998.

If the BATFE did indeed submit the final rule for internal DOJ review (which could take a year or more) in February, I sure wish someone in the DOJ would leak it.

Useful documents. But you might want to provide an up to date version of the Federal law (also on your regulatory resource page) that includes the changes from the Safe Explosives Act. I don't know of a pdf version but this is where I go to read it:

I'm gonna try to reformat this thread. Hope I don't trash it...

manufactures.

-----snip-----

I know that Anthony Cesaroni and Gary Rosenfield are following this thread. Perhaps they'd like to comment ? Pesonally I think we need to approach the concept of adjustable delay time from the other end.

First re-write the test parameters published by NAR and TRA to include verbiage outlining a test procedure to certify a manufacturer's process for adjusting delay times without requiring set, specific delay times.

Secondly, test the motors using 2-3 delay times adjusted per the manufacturer's procedure to certify accurate, repeatable results.

That way, the choice is left up to the manufacturer. If they feel that we shouldn't mess with their available reload times, then they don't have to submit anything for testing and certification. If they do believe we can modify the delay element in a safe manner to produce the custom delay needed for a particular flight then they can submit that process for certification.

And, we flyers can vote with our wallets for the manufacturer who best meets our needs in matching motor delay time to our rockets.

Alternatively, we could revise the sections of the code about motors to specifically exclude any reference to delay time. That way we could drill as necessary (just like we choose the proper amount of BP for an ejection charge) without violating any of the Safety Code provisions and the manufacturer's don't have to bear the cost of providing testing samples.

Or, I have to add additional deadweight to my rocket to match the flight profile to the handful of available delay times :-(

Times and technology change. When I started flying back in the Sixties having a Safety Code which prohibited any modifications to the motor was just plain good sense. We shouldn't have been messing around with the available BP motors. But we're not in Kansas anymore, Toto. Right now the *only* flight event which is beyond my control (because both AT and CTI provide instructions in adjusting the size of the BP ejection charge) is the exact (not quantized) ejection delay time. We need to modify our Code and certification process to acknowledge that fact.

Personally, unless the rules can be revised my solution to provide the exact 11 second delay my Streak needs is to utilize the apogee detect capability of my RRC2 altimeter to get the streamer out at the right time and not use the motor's ejection charge at all. Well, that's not entirely accurate, I will recycle the BP from the reload kit into a canister fired by the altimeter :-).

John

In article snipped-for-privacy@corp.supernews.com, Jerry Irvine at snipped-for-privacy@gte.net wrote on 4/9/05 8:02 AM:

We're already living the (a) (7) "lifestyle". We'll resume living the (a) (8) lifestyle once it's upheld by the court.

Gary/RCS

include

process

times.

Sixties

Well said, John! It seems to me that trying to get adjustable delays certified under rules created for non-adjustable delays is like trying to put a square peg into a round hole.

Gary, that's a perfectly rational, logical, intelligent approach! What are you trying to do, make Jerry's head explode? ;)

I'd buy tickets for that event!

I find it interesting that it seems (atleast as far as my newreader goes), there have been no posts from TMT/S&T/CAR as to the testing for "variable delays" for any motors, and how it impacts motor testing...

We call know that CTI and AT want it to be cool, but even the principals there have not provided any doc or copied emails as to what the procedure actually is....(from the testing authority) (I'm sorry if I missed it)

It just seems that this whole "adjustable delay" thing is driven by manufactures, and the testing authories don't really know what to make of them.

If you read the requirements for testing, the manufacturer must provide x motors with each delay for testing (say 3x10sec delays), so that it can be confirmed that the 10 sec delay is within the required parameters (+/-

How the heck does this fit with "adjustable delays" unless the testing folks are just told to "trust us" by the manufacturers?

Part of "rocket science" is not to adjust the delay to the bird, but is also to "adjust the bird to the delay", and THAT should be the lesson that people learn when flying!

Since 1990 (R&R,RMS) means for 15 years now.

I told you so. (for decades).

Yes.

Each time I have formally proposed it it has been rejected.

Perhaps you can propose it and it will be accepted post haste.

Unless you are banned.

Which I guess would be interpreted by the existing lovers of bad rules as a motor modification in violation of the safety code :)

It was.

So can we start yet?

Bruce Kelly had to split his time too. I assume he is forgiven as well.

The provision is.

Poor shunned jerry.

"variable

There are rarely any official posts to this forum, largely due to the propensity of certain individuals to treat every post from the orgs as an opportunity to ramp up the level of attacks on the orgs and/or the person making the post.

So do the flyers. Rules that made sense for Estes BP motors make no sense for composites. People have been adjusting delays safely ever since composite motors became popular. Delay tools for this purpose were introduced many years ago. It's long past time that the cert process caught up with the times and the technology.

procedure

CTI has previously discussed the process involved in getting their adustable-delay Pro38s tested and approved. However I don't recall where or when that discussion took place.

You say that like it's a bad thing.

provide x

testing folks

Those rules are outdated, written for an age when all motors had specific delays. We should not be limited by

Maybe in the days of Estes, but this is the 21st century. We should not be hamstrung by the outdated attitudes of the past, when there was no safe and simple way to adjust delays for optimal performance.