Old 98/5120 98mm casing and closures

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t-rocket

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Need old timers help-

I have an old AT 98/5120 casing that I used to fly in bigger rockets back in the mid-'90s. The closures are just as old. I was out of rocketry for 15 years and I haven't purchased a big AT motor since 1997, and wondering what's changed with these reloads?

I can see now the current L952W reload is only sold as a plugged motor—although the forward closure on my old casing has an ejection well. The design of the new 98mm forward closure is different-looking than the old one and there is a seal disk now when there wasn't one used 20 years ago.

My question: Can I use the old forward closure with the new reloads? I assume I would have to seal off the end since there isn't a delay grain any longer. Would the parts still fit correctly?

Or will I have to buy a new forward closure?
 

Rocketjunkie

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You can use the old closure but you must seal the touch hole. There are no O-rings to seal the delay grain, it just drops into a plugged closure. I still have some ejection well closures. I tapped the touch hole and used a short screw to seal the hole. You will need to buy a seal disk. The new L2500ST requires a stainless steel seal disk (can be used with the other loads but it's heavy).
 

ECayemberg

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You can use the old closure but you must seal the touch hole. There are no O-rings to seal the delay grain, it just drops into a plugged closure. I still have some ejection well closures. I tapped the touch hole and used a short screw to seal the hole. You will need to buy a seal disk. The new L2500ST requires a stainless steel seal disk (can be used with the other loads but it's heavy).
Very similar to Tom's remarks. I have an old forward closure as well. I drilled out the ejection charge hole to accept a forged eyebolt, installed the eye, backed with a washer and nut, covered it in JB weld. Now I have a sealed forward closure with hard point for recovery connection if desired. I do have to shorten the smoke grains slightly to accommodate the nut & JB weld, but no biggie!
 

jimzcatz

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I'm surprised some of "those guyz" didn't harp on you "modifying" your motors!
 

t-rocket

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Thanks for the replies. I plan to use the L952W reload as it was always one of my favorite motors. I bought the standard seal disk. So, the delay element is gone from the kit, correct? It was replaced with a smoke element, right? Another person said I just needed to assemble using the seal disk, fill the ejection well hole with grease and tape it off real good. Sound right?

T Dungan
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Rocketjunkie

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The delay element and smoke grain are the same thing. You must seal the touch hole against pressure. The old reloads had O-rings thet went into the bottom of the dekay well to seal against pressure - they are not included in the kit any more. Another option is to rough up the inside of the ejection well (on the outside of the motor - NOT where the smoke grain goes) and fill with epoxy.
 

CoyoteNumber2

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Post retracted. [Unable to delete due to new site policy.]
 

Rocketjunkie

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I've done that with 54s without issue; I doubt a 98 would be any different. I pack a little dog barf on top of the grease too for good measure.
The 54s still have the delay well sealing o-rings and you can just leave out the BP ejection. The 98s don't have these O-rings and therefore there is nothing to prevent the pressure from going around the smoke charge to the touch hole. (When the 98s had motor ejection, there was a washer and 2 concentric O-rings placed in the delay well before the delay (smoke) grain was installed.) After the motors were sold as plugged, these O-rings were included for a few years but were eventually discontinued. You MUST seal the forward closure well enough to withstand motor pressure.
 

CoyoteNumber2

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The 54s still have the delay well sealing o-rings and you can just leave out the BP ejection. The 98s don't have these O-rings and therefore there is nothing to prevent the pressure from going around the smoke charge to the touch hole. (When the 98s had motor ejection, there was a washer and 2 concentric O-rings placed in the delay well before the delay (smoke) grain was installed.) After the motors were sold as plugged, these O-rings were included for a few years but were eventually discontinued. You MUST seal the forward closure well enough to withstand motor pressure.
Valid point. I have retracted my misinformation.
 
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