[F-FT] Regarding Aerotech RMS motor delays

Gary has just announced official endorsement of the policy of drilling delay grains on The Rocketry Forum under the 'Vendors' section.
Full information is available on the AeroTech website under the 'News' section.
My great appreciation and thanks to Gary for following this through in an EXTREMELY expeditious manner!!!
David Erbas-White
Reply to
David Erbas-White
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Great job David.
now can you pull the same on Estes to get them to allow motors to be glued together again ?
we did this in the 60s & 70s. It was published in the NAR model racketeer on how to do it.
now we need Estes to say it's ok, since we have the manufacture must approve motor mods rule.
IE tandem motors.
ohh by the way, I have a 70s NAR model racketeer reporting on removing ejection to make delayed staging booster engines. if we could do that yet again ;-)
Reply to
AlMax
I've had at least 3 different manufacturers of SU motors adjust the delays on them for me back in the "good old days". And many SU motors are made with long delays and then drilled down as part of the manufacturing process. It was all done before reloads were invented. There is absolutely no technical reason that whatever AT or CTI or any one else comes up with has to be limited to reloadable motors.
Bob Kaplow NAR # 18L TRA # "Impeach the TRA BoD" >>> To reply, remove the TRABoD!
Reply to
Bob Kaplow
instructions
Well...several decades ago I learned the hard way that drilling into an Estes C to increase the ignition surface available at launch was a bad idea. Spectacular CATO, though. Fifteen feet away. Wish I'd been wearing tan shorts :-)
My concern is the casual shopper at Wally-World who picks up a quick-start set, never before having even seen an MR really shouldn't be doing mods to the motor because they don't have a clue about what the possible consequences are.
I agree that there is no technical reason why delay grain modification should be limited to only reloadable motors. But I believe there are several practical reasons why it would be a bad idea.
John
Reply to
John Bonnett
Actually, if I was to want to do anything (), it would be to change the rules that decertify certain single-use motors.
It makes no sense that I can't fly an A10-0T from the 90's, when I can fly an A8-3 from the 60's.
David Erbas-White
Reply to
David Erbas-White
Drilling a delay on a single use motor has at least one advantage: you can't drill the wrong side of the delay. I've seen in the other thread someone saying "Doesn't matter which side is drilled.". If I understand correctly the way a motor works, this shouldn't be true. Side facing the combustion chambre burns under pressure, and so probably not at the same speed than the other side. So side does matter.
But there is also one disadvantage: you have to remove the ejection charge and then replace it after the mod. Not easy with an estes-like motor.
Note also that, a few years ago, when apogee were still sending motor to me (in europe) (by post), he tried to sell me 10 seconds delay motors because other ones were not in stock, and was ready to explain me how to modify this to have the desired delay. At this time, I refused. This seemed to me a violation of the code.
"John Bonnett" a écrit dans le message de news:425c6e7f$1 snipped-for-privacy@newspeer2.tds.net...
Reply to
michel
The web thus burn time is same regardless of which side is drilled. Drilling the delay grain on the chamber side is the correct method however. The reason is better structural support of the delay grain as well as a configuration better suited to pressure loading without deformation. Hydrostatically test some delay grains in both configurations, especially some that rely on O ring seals and you'll see what I mean. It also provides better continuity in the delay train with the ejection charge.
Anthony J. Cesaroni President/CEO Cesaroni Technology/Cesaroni Aerospace
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(905) 887-2370 x222 Toronto (410) 571-8292 Annapolis
Reply to
Anthony Cesaroni
Correct. The disadvantage to drilling the top is the delay keeps burning for a while after ejection thus cooking the inside of the rocket more.
It was probably (probably :-) ) a violation of postal rules.
It would have been legal to mod the delay had he publicly stated the mod was a recommended procedure (similar to what Gary recently did), which he didn't.
Wanna see something funny? Search rmr archives for posts from me suggesting Gary post the delay mod permission. They go back years and are present regularly over time.
Jerry
Reply to
Jerry Irvine
Agreed. They just do not ever become "unsafe" or "out of performance range".
The only motor EVER cited as going out of range was motors by Prodyne-Rahkonen and that was because he used radical catalysts he got from work at Thiokol or whatever.
Jerry
Reply to
Jerry Irvine
jerry, are you looking for acknowledgment that people have generally been ignoring you for years?
Did you mean "funny" or "pathetic"?
Reply to
Dave Grayvis
Ineffectual comes to mind. David does in a day or two what Jerry couldn't do in years. Hey Jerry I think I hear Gary laughing at you.
Reply to
Phil Stein
How many hundreds or thousands of flights (people enjoying added safety) could have been flown with properly modified delays at certified NAR or TRA launches if only Gary had published this 10 years ago?
I told you so.
On the record.
Reply to
Jerry Irvine
I agree.
With the "loss of useful time" to hundreds of comsumers for over 10 years.
I stand amused.
I advocated for consumers WITHIN THE RULES.
I told you so. ON THE RECORD.
Jerry
"As for your name calling, if you don't like what I am saying thats understandable , but if your just rude and nasty -- you probably have a place in hell waiting for you!" - anon from an email list
"The value was back when I said, and carefully described why, I told you so." -Jerry Irvine
Reply to
Jerry Irvine
Your right. that is much more important !
I have a few packs of A10-0s I have to fly at the park instead of at the large launch.
Reply to
AlMax
Added safety and peril are not the same thing. Also, the mods we are talking about were not that uncommon - even before Gary published the instructions.
Reply to
Phil Stein

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