Plugged fore closure

[Steven88]

Hello. I have never flown a plugged motor. I would like to know more about them. Can you use a plugged motor with an open fore closure or do they only fly successfully in a casing with a plugged fore closure?

 

[Steve Shannon]

Hello. I have never flown a plugged motor. I would like to know more about them. Can you use a plugged motor with an open fore closure or do they only fly successfully in a casing with a plugged fore closure?

It’s only a plugged motor if you use a plugged forward closure.
But, discarding the ejection charge does pretty much the same thing. The delay grain burns for some period of time after the motor burns out. With no ejection charge to ignite there’s nothing creating pressure forward of the forward closure. Some people place grease in the ejection charge well.
Whatever you do, don’t leave out the delay grain.

 

[Cameron Anderson]

Most plugged motors are plugged because standard delay grains don't burn long enough to allow for reliable motor ejection after coast.

I wouldn't play too much mixing plugged motor options with open closures.

 

[watheyak]

Yes, you can certainly do this. Often times you have no choice, as with CTI motors.

In addition to grease as Steve suggests, you can fill the charge well with dog barf and cap it with tape. There's some debate as to whether that's even necessary.

 

[Tim51]

What's the thinking behind filling the empty charge well with grease / wadding? I've flown several loads with the charge removed as and when necessary, with no problems, but I didn't grease or tape off the charge well.

 

[tim cubbedge]

What's the thinking behind filling the empty charge well with grease / wadding? I've flown several loads with the charge removed as and when necessary, with no problems, but I didn't grease or tape off the charge well.

I was told to do it by my local CTI dealer. The concern is/was burn through from touch hole. I’ve never seen any indication of said burn through but for the time it takes to stuff/tape dog barf into it, what’s the harm?

 

[Tim51]

I was told to do it by my local CTI dealer. The concern is/was burn through from touch hole. I’ve never seen any indication of said burn through but for the time it takes to stuff/tape dog barf into it, what’s the harm?

Yes - fair enough. Will do it in future. Thanks.

 

[Steven88]

Ok. Thanks a bunch for the information.

 

[Steve Shannon]

What's the thinking behind filling the empty charge well with grease / wadding? I've flown several loads with the charge removed as and when necessary, with no problems, but I didn't grease or tape off the charge well.

It just catches random sparks from the delay grain as it nears the touch hole. It won’t help at all if you have a high pressure burn through or if high pressure gases bypass the delay.

 

[Dugway]

With my Saturn V, the four 24mm outboard motor tubes are all sealed at the top against a bulkhead. I use Aerotech 24mm reloads and for the first launch I filled the charge wells with grease and then taped over the top with aluminum tape. After the flight, all four tape covers were still intact. For the next flight I skipped the grease, since it's kind of a pain to clean up, and just used the aluminum tape. Again, all of the tape was intact after the flight. Going forward I'm going to skip the grease.