Short delay for AT I245G

[Balsa Bob]

Can anyone tell me the correct reload delay kit (RDK) to change from medium to short delay time? The AT website says refer to the
RDK cross-reference list on back of the reload kit header card, but I don't have a motor in my possession. Thanks in advance.

 

[WillMarchant]

The Aerotech delay lengths cross reference doesn't list the I245G.

 

[jimzcatz]

Seeing as you want to remove 4 seconds,just drill a 4/32nds hole in the forward end of the delay grain with a 1/8 in drill bit. I cant see wasteing money in delay kits. I trim all my delays when necessary.

 

[Handeman]

Seeing as you want to remove 4 seconds,just drill a 4/32nds hole in the forward end of the delay grain with a 1/8 in drill bit. I cant see wasteing money in delay kits. I trim all my delays when necessary.

Jim, just for clarification, don't you mean the aft end of the delay grain, the end toward the propellant?

 

[TD Sky]

I think it is the forward end, AND the ejection powder must fill the hole. That way the ejection powder is 4/32 closer to the aft end of the delay charge and a 4 second decrease in delay is achieved. Just drilling a hole in the delay and pointing the hole at the propellant does not "defeat" the time-fuse affect of the delay element immediately adjacent to the hole. In other words, a 4/32 hole on the forward end filled with BP makes the delay grain effectively 4/32 shorter. Putting the hole on the aft end makes the delay grain a full length grain with a hole in it.

 

[jimzcatz]

Jim, just for clarification, don't you mean the aft end of the delay grain, the end toward the propellant?

I started drilling delays in the old days on single use motors,so the forward end is what was always drilled. I'm pretty sure it will work both ways,but with the hole in the forward end,it seems to work much better.

 

[Handeman]

The Aerotech instructions read as follows:

4. Install the modified delay module into the RMS™ motor forward closure with the drilled end facing the combustion chamber (propellant). Finish assembling the RMS™ motor according to the instructions that accompanied your particular reload kit.

I assume there is a good reason for this, but since I've never used an adjusted delay, I'll defer to those that have.

 

[tbonerocketeer]

or just use a short for a red, as they burn similar times. (I218)

 

[TWRackers]

Can anyone tell me the correct reload delay kit (RDK) to change from medium to short delay time? The AT website says refer to the
RDK cross-reference list on back of the reload kit header card, but I don't have a motor in my possession. Thanks in advance.

"Bob",

Are you flying that motor at MDRA this weekend? If so, which day(s) are you planning to be there? I've got an I245G I'm going to try to fly on Sunday.

 

[terryg]

This just shows we need more green reloads, since I tend to just fly the next larger engine so I do not have to mess with the delay!

 

[cjl]

Try the J500

 

[Donaldsrockets]

The I245G is a great motor, you'll love it.

Here's my Binder Stealth going up on one.

Got another one in my box that I'm hoping to fly in my LOC IV.

 

[blackjack2564]

I concur with Jim, I've shortened single use and the only way is through the front. Cesaroni the normal way is through the back. AT re-loads, either way will work just as good. This is from doing it dozens of times and being successful.

Since they don't make RDK's for the green yet, you are better off shortening the delay, than switching. At least you know what you'll get.

 

[Balsa Bob]

Thanks, everyone...
I'll try my hand at drilling the delay and will update y'all following NARAM 51.