Adjusting Aerotech delays

Using the same reloads as I described in my other post. E18W-10, 24 mm RMS.
wRASP said that I needed a 4 second delay to get to apogee with my 9.5 ounce
Phoenix. The delay for the E18s were 10 seconds. Here are the calcs....
10 second delay, 2 second motor burn, 12 second total delay element burn. 16mm long delay element 16mm/12 seconds = 1.33 mm/second burn rate.
I needed 4 seconds delay plus 2 seconds burn so 6 seconds total.
This one is easy cuz 6 is half of 12 so I needed to drill in 8 mm to get to 6 seconds. I left it just a little shy of the full 8 mm so it goes after the turn at the top. It went off just after the turn at the top.
Same motor for the Airspike. wRASP says I needed 6 seconds.
6 second delay plus 2 second burn = 8 seconds. 12 seconds - 8 seconds means I have to remove 4 seconds.
4seconds at 1.33 mm/second = 5.33 mm
I drilled about 5 mm and got an ejection right at the top.
My son was timing the burns, but I think he started at first smoke instead of liftoff (when the real burning starts). These old white lightnings are tough to light. He got about 8 for the Phoenix, which should have been 6. I guess I shoulda let him push the button and leave me to do the timing. Next time.
I would expect that there is at least a little delay between grain ignition and delay ignition, which may account for part of the "bonus delay" that we always here about. I would expect it even more here since the E18 does not fill the whole case and has the masking tape at the end of the grain for the ignitor to butt against. The F's that fill the whole case would probably ignite both nearly simultaneously, minimizing that difference.
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Oops!!
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Jerry Irvine, Box 1242, Claremont, California 91711 USA
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WRONG!!!!
We have our first "poster child for you you shouldn't modify delays unless you REALLY understand what yuou're doing".
Go back and re-read the AeroTech delay modification instructions. The delay burnoff is SIGNIFICANTLY faster while the motor burns compared to after burnout.
    Bob Kaplow    NAR # 18L    TRA # "Impeach the TRA BoD"         >>> To reply, remove the TRABoD! <<< Kaplow Klips & Baffle:    http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org
You need only reflect that one of the best ways to get yourself a reputation as a dangerous citizen these days is to go about repeating the very phrases which our founding fathers used in the struggle for independence. -- Charles A. Beard
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Poster child here.
The directions tell you how, but don't' tell you why. The directions say "the drill depth can be approximately determined by multiplying the number of seconds of delay time reduction desired by .024"-.031" per second." This statement definitely makes more sense in light of your comment, so lets run the numbers.
Putting it back into mm (cuz that's how I measured the first time) delay reduction is 0.61 to 0.79 mm/s. So 10 seconds of delay is 6.1 to 7.9 mm and the motor consumes 8.1 to 9.9 mm of delay element. I know that it is not 8.1 mm for White Lightning because the ejection charge did not fire at burnout and I drilled an 8 mm hole into the delay.
It looks like the truth lies between my method and Aerotechs.
Let's look at some alternatives. Lets say the delay burns at the average published rate - about 0.7mm/s. Then 4 seconds of delay is 2.8mm. So 5.2 mm of delay was eaten during propellant burn.
Same load drilled to 5 mm leaves 11mm. Eat 5.2 during propellant burn, 5.8 left over, 5.8/0.7 = 8 second delay. Well within the accuracy of my crude timing.
The real unknown here, is how fast the delay grain lights after the propellant ignites. The "small" reloads have a piece of tape over the slot to provide a stop for the ignitor. I would expect this to blow right off from the pressure of the burn. Could this be the source of the bonus delay?
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Tom Koszuta
Western New York Sailplane and Electric Flyers
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The tried and true method of delay reduction assumes the delay is initially correct. We know to a near certainty that is not the case with most AT delays. Bonus is common.
1/32 inches per second is very accurate. 0.794 mm/s 0.8 if rounded.

It is unknowable without testing either. Even the manufacturer cannot reliably predict it.

Yes.
One of them.
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Jerry Irvine, Box 1242, Claremont, California 91711 USA
Opinion, the whole thing. <mail to: snipped-for-privacy@gte.net>
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Jerry et al wrote,

Jerry,
We don't seem to have a problem, but then again our initiation sequence is different.
Anthony J. Cesaroni President/CEO Cesaroni Technology/Cesaroni Aerospace http://www.cesaronitech.com / (905) 887-2370 x222 Toronto (941) 360-3100 x101 Sarasota (410) 571-8292 Annapolis

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Another variable everyone seems to have left out .....is the + or - 20% on the delay time.... that is specfied .....and as has been said before considering the age of the grain.....the amount of time from ignition to full pressure before lift off, the count should begin from ignition.......on small, old motors, I have had them sit on the pad for 2-3 sec. before launch, while they were coming up to pressure, due to age and difficulty lighting....jim h.
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That is a NFPA standard to "tolerate BP motor variances"
AT makes APCP motors.
More to the point, given how wide a tolerance it is (and the simple fact it is codified with AT's principal on the committee), why is exceeding that tolerance by AT by RCS tolerated at all?
Make the rules, follow the rules? Nope!

Yet another NFPA violation. No kidding!
Jerry
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Jerry Irvine, Box 1242, Claremont, California 91711 USA
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Jerry Irvine wrote:

It applies to all motors.

What verifiable proof do you have that AT or any other manufacturer is exceeding the tolerance? "Jerry says so" isn't proof of anything.

What NFPA code regulates speed of ignition?
BTW, I recall quite clearly the time I tried to fly your K firestarter. It sat smoldering on the pad a lot longer than 3 seconds, then produced a short burst of thrust sufficient to lift it 20 feet into the air. It didn't come up to full pressure until after it hit the ground. That was a NEW motor too, not an old one. You ought to remember this incident too, since you were present at the launch. So if you're going to claim that AT is somehow violating NFPA codes because an old motor was a little slow to light, you'd better take the beam out of your own eye first.
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Look at the delay test results on the NAR S&T web pages. It clearly shows that several of the AT delays are seriously wacked from what AT claims they are. In fact, in order to get them certified, AT had to chenge the designations, but they did it in a way that is VERY confusing. THe F39-6 is NAR certified as an F39-3 and the F39-9 is certified as an F39-6. So when someone refers to t he F39-6, which one are thye refering to.
TRA keeps all of the delay test results a secret, in violation of NFPA requirements. No one outside TMT knows how accurate the delays they tested are, if they actually comply with NFPA requirements, of if TMT even tests the delays for accuracy. It's been a huge ongoing cover-up since 1994. And it leaves TRA and TMT open to huge liability if a serioius accident ever results from a TMT certified motor with an innaccurate delay.
    Bob Kaplow    NAR # 18L    TRA # "Impeach the TRA BoD"         >>> To reply, remove the TRABoD! <<< Kaplow Klips & Baffle:    http://nira-rocketry.org/LeadingEdge/Phantom4000.pdf www.encompasserve.org/~kaplow_r/ www.nira-rocketry.org www.nar.org
I'm not afraid of terrorists. I am terrorized by airport security. _george
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Many, many, many posts to rmr?
Direct observation at group launches?

You don't know?

The rule was not added yet. Maybe it was my fault?
Jerry
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Jerry Irvine, Box 1242, Claremont, California 91711 USA
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Jerry Irvine wrote:

Well Jerry, your ignorance of what constitutes "verifiable proof" certainly hasn't improved in the years since I saw you in court. As you may recall, at that time you thought that writing "stolen motor" on someone's flight card constituted legal evidence that the motor was stolen.

Your word is less than worthless, especially in regard to anything related to Aerotech or TRA. And your statement that "bonus delays are common" doesn't match my own observations, nor that of anyone else I know. Besides, how many sanctioned launches have you attended recently, without being kicked out? How often do you fly AT motors?

You're the one who claims such a regulation exists, so prove it. Post the NFPA code that regulates the speed of ignition -- I'm sure we'd all be interested in reading it, and finding out exactly how much time a motor is allowed to take coming up to pressure.
You're so fond of quoting idiots calling you a hero, or quoting CFRs out of context. Yet whenever you make this ridiculous claims, suddenly you're reluctant to quote anything relevant to your claim.
i
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wrote:

...
Don't you have a copy of the safety code Ray?
From the HPR Safety Code (aka NFPA 1127) dated "2/98 1:02":
2-12 Ignition Systems. ... 2-12.3 The launch system and igniter combination shall be designed, installed, and operated so the liftoff of the rocket shall occur winthin three seconds of actuation of the launch system. ...
An old NAR Model Rocket Safety Code from 7/99 (presumably based on NFPA 1122) required 1 second (this is for model rockets only).
Dave Morey
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Dave Morey wrote:

That pertains to igniter and launch systems, not the motor; unless I'm reading the quote wrong??

Fred Wallace
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You are OFTEN wrong, especially including now. You obviously cannot read the obvious (again).

Jerry
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Jerry Irvine, Box 1242, Claremont, California 91711 USA
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Jerry Irvine wrote:

Just curious...
It appears that the wording says that it should be designed, installed, and operated so that the liftoff occurs within three seconds...
Just what, exactly, happens if something does not work as designed?
So, the next time that I have an igniter burn through without the rocket lifting off, I should be arrested?
If that is the case, is there any rocketeer, anywhere, that shouldn't immediately have the book thrown at them???
Get real. The intent of the law is obviously meant that OPTIMALLY, these are the things that should occur. Just as congress could not repeal the law of gravity, there is no law that is going to be able to repeal the laws of physics. Realistically, things occur that prevent things from occurring optimally. The only way I could see anyone ever being prosecuted under this law would be if the DESIGN were such that the system didn't operate properly within three seconds. For example, if I had a system with a built in delay (for whatever reason) such that there's no possibility that the liftoff couldn't occur in three seconds, I would be violating the law (using some Rube Goldberg device from the 'mousetrap' game comes to mind). But there's simply no WAY that this law is enforceable, as it attempts to overrule the laws of physics.
For example, the law says that you must not run into the car in front of you. But, if your brakes fail, did you break the law??? No, you didn't (even though you might be CIVILLY liable, but that's an example of @#$@ happens).
So, what exactly is your POINT (sorry, couldn't resist) here, Jerry?
David Erbas-White
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David Erbas-White wrote:

Please don't confuse Jerry with facts based on common sense; it only confuses and frustrates him. Sorry, I couldn't resist..(:-)
Fred
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At least you didn't do anything silly like add value to the conversation.
Thank you.
Jerry
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Jerry Irvine, Box 1242, Claremont, California 91711 USA
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As I have said repeatedly, due to poor rule authoring, EVERYTHING we do is technically illegal at some point.
Hence why we should shift to exemptions not regulations. We HAVE the authority to do so.
In those few areas where they do not already exist, mainly regs authored by NAR and TRA themselves.
Jerry

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Jerry Irvine, Box 1242, Claremont, California 91711 USA
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Jerry Irvine wrote:

If you think rocketry should be exempt from all regulations, including state fire regs, you're an idiot. If you think there's even a ghost of a chance that rocketry ever could be exempted from all regs, you're a delusional idiot.

Well, that's settled. You're a delusional idiot.

TRA/NAR do not work in a vacuum, nor do they have authority to write regs without oversight or input from regulatory agencies. They cannot unilaterally grant exemptions nor can they force any regulatory agency to capitulate to their wishes. You know that, of course, but you'd much rather rant and rave against your perceived enemies than face reality.
f
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