AT motor and reload questions

[DynaSoar]

AT's 38mm RMS motors all say "plugged forward closure". I take this to mean they're designed thrust only, no delay + ejection. Yet their 38mm reloads come with various delays, which I take to mean ejection charges. What am I missing? Do the same motors serve double duty, or does the plugged closure mean something else?

While we're at it, once I have a motor of a certain diameter, what do I need to use a different reload other than what my casing is made for? Anything more than just a longer casing?

 

[aksarben10]

Correct, the plugged closure is used when you do not want a motor ejection and will be using electronics.

As to the motor casing, you can only use the motors listed for that casing length. You need the different lengths for different impluse classes. The reloads are designed with different liner sleeves that would not fit in a longer tube and thus they would not seal correctly.

Scott

 

[DynaSoar]

Originally posted by aksarben10
Correct, the plugged closure is used when you do not want a motor ejection and will be using electronics.

As to the motor casing, you can only use the motors listed for that casing length. You need the different lengths for different impluse classes. The reloads are designed with different liner sleeves that would not fit in a longer tube and thus they would not seal correctly.

Scott

So, for ejection charges, I just leave the plugged end off? Or do I need a different fore end that's not plugged?

 

[Elapid]

in place of the sealed closure.

 

[BlueNinja]

I think the delay is in there for a smoke generator during the coast.

 

[UhClem]

"AT's 38mm RMS motors all say "plugged forward closure""

"38mm std. or plugged forward closure" is what I see in the part list and the front page of the instructions shows the plugged closure as an option.

In any case, the motor is normally assembled using the standard forward closure.

The plugged forward closure is the same as the standard except that it has no ejection charge well or touch hole to ignite the ejection charge. It still has the space to install the delay except now all the delay does is make smoke.

Why would anyone want a plugged forward closure when you can acheive similar results just by leaving out the ejection charge? One of the failure modes in the RMS system is a failure of the seal inside the forward closure. This turns the ejection charge touch hole into a new nozzle that roasts the inside of your rocket. Without that hole, this can't happen. This is a fairly rare failure.

Without a motor ejection charge, some other means must be used to control recovery system deployment.

As for what parts you need to use other reloads, read the instructions for the reload. All of the instructions for the Aerotech 38mm reloads are available in the Resources section of the Aerotech web site.

 

[firemanup]

When i don't want motor ejection i just use the standard closure, fill the well with hard packed in dog barf wadding and then tape it closed.....

Works fine and I don't need one of the plugged closures... dog barf is mucho cheaper than another closure..

 

[solrules]

Originally posted by UhClem

Why would anyone want a plugged forward closure when you can acheive similar results just by leaving out the ejection charge? One of the failure modes in the RMS system is a failure of the seal inside the forward closure. This turns the ejection charge touch hole into a new nozzle that roasts the inside of your rocket. Without that hole, this can't happen. This is a fairly rare failure.

You may want to buy a plugged closure for two reasons:

1. Ejection charge pressure can't leak out of the hole (in large clusters this can become a problem)

2. You can drill and tap the forward closure to insert an eyebolt for the strongest shock cord mount on your rocket. Just make sure to threadlock it so that it won't spin itself loose (also good in clusters where centering ring space is minimal)