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Pyrodex Pellets vs. Triple-7 Pellets

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timbucktoo

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Is there any difference between the two when used for motor starting? Better, worse, no difference, don't use?
I recently acquired some AT 75mm reloads but they don't come with starters. I have found multiple posts about Pyrodex pellets used with e-matches for motor starting but very little if any about Triple-7 pellets. Triple-7 pellets are available locally and wanted to make sure they can be used as an alternative.

Thanks!
 

markkoelsch

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I have not used them, but from a shooting perspective they are designed as a direct replacement for the Pyrodex pellets.
 

Banzai88

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Wal Mart carries Pyrodex pellets, if that helps.
 

cwbullet

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Triple 7 contains charcoal, Potassium perchlorate, potassium nitrate, dextrin. dicyanamide, and sodium benzonate.

Prodex contains Charcoal, graphite, sulfur, Poatassium nitrate, and potassium perchlorate.

This is off the MSDS.

If I remember my shooting days, I think pyrodex makes more smoke. I note sure if they perform any differently.
 

manixFan

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Based on my limited testing Triple7 is more energetic than Pyrodex. As a BP substitute T7 is a lot closer than Pyrodex. It produces a lot less physical residue as well. For ejection charges it also has the added benefit of not producing sulphur so it's not as corrosive. As a starter I would choose Triple7 over Pyrodex. It would be instructive to put a pellet into a tube the same diameter as a typical core and fire it with an e-match so you know what to expect.


Tony
 

cwbullet

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That makes sense with the sulfur.
 

sharkbait

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I have used both. Tony is correct, 777 is a faster more energetic burn with less smoke. Either one will work, but I prefer the slower burning Pyrodex. I actually now mostly cast my own pellets directly in the head of the top grain for anything larger than a 38mm motor using a mix of 65% PyroDex RS powder and 35% Duco Cement.
 

timbucktoo

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Thanks for the feeback. I did find some Pyrodex pellets today but they were 30 grain. I saw in another post all that was mentioned was 50 grain. Anyone used the 30 grain?
 

sharkbait

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Pellets come in the following sizes:

.54 caliber 60 grain
.50 caliber 50 grain
.44/45 caliber 30 grain

Depends on what type of propellant you're trying to light but on a typical 76mm motor I would use two .50 cal 50 grain pellets, so you should be good with three .44/45 cal 30 grain pellets.
 

manixFan

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I have used both. Tony is correct, 777 is a faster more energetic burn with less smoke. Either one will work, but I prefer the slower burning Pyrodex. I actually now mostly cast my own pellets directly in the head of the top grain for anything larger than a 38mm motor using a mix of 65% PyroDex RS powder and 35% Duco Cement.
I've got to try the Duco cement mix. I bet it works very well.

Do you cast with a hole in the middle like the CTI BP grains? Or just as a solid fill in the grain?

The reason it seems to me that T7 would be better is that since it burns faster it would help get the core pressure up to help sustain ignition. But good to hear that based on your experience Pyrodex works well. I have a lot of both and using the Pyrodex to help start motors would be a good use for it. I can save the T7 for use in ejection charges.


Tony
 

sharkbait

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100% success rate with the cast pellets. This also makes air starting motors much easier and reliable.
The cheap Chinese E-matches work great here as they actually burn rather than pop. Yes on a mandrel with a 1/4" core through the pellet, very similar to CTI.

I have a detailed post on the process in the Restricted Research sub forum under the "how to light an M at 20,000" thread.
 

manixFan

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100% success rate with the cast pellets. This also makes air starting motors much easier and reliable.
The cheap Chinese E-matches work great here as they actually burn rather than pop. Yes on a mandrel with a 1/4" core through the pellet, very similar to CTI.

I have a detailed post on the process in the Restricted Research sub forum under the "how to light an M at 20,000" thread.
Great, thanks for that info. I have access to that forum so I'll check it out. I want to light one of Scotts 38mm K627s as a sustainer at altitude and using a cast pellet seems like a good way to do it.

I have also tested some of the cheap e-matches you mention and while pretty variable, they do burn rather than pop. Below is a sample frame of a video I made of one of the tests. One popped pretty hard but they all burned fairly well. You can see that at .3 seconds they all have a good flame still.


Tony

ematch-test.jpg
 

Onebadhawk

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I have used pyrodex 50 grain 50 cal pellets to light every motor I fly for a few years now...
1/2 a pellet in a 38 mm motor..
1 pellet in a 54 mm motor..
2 or 3 pellets in 75 mm motors...
I also use this method to do the airstarts in my scratch "Europa Express"..
The e matches work perfectly with this method..
Before this I was making my own ignitors with limited sucess...
When doing an airstart the extra mass at the head of a hand dipped ignitor
would make the ignitor more likely to be forced down by the G's of ignition of the main motor on the pad...

And 777 burns faster then pyrodex,, that's exactly why it works better in a muzzleloader,, less lock time...
To light a HP motor you want a slower burn.......

Teddy
 

sharkbait

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Spot on Teddy.

While I cast my on pellets in 54's and up, I use a 1/2 pellet in 38's also. They are easily cut by pressing down with a single edge razor blade and rolling them, they pretty much snap in half after scoring them. I also glue my pellet in the top grain with Duco cement to prevent it from sliding down the stack, this is most beneficial when air-starting to resist the G's. 29's get a 1/2 pellet also but you have to carefully shave them down with a razor for fitment. I use a brass tube to push over them after rough shaving with the razor for a nice clean round pellet.
 

manixFan

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And 777 burns faster then pyrodex,, that's exactly why it works better in a muzzleloader,, less lock time...
To light a HP motor you want a slower burn.......
I guess I have the exact opposite idea. Since AP burns best under pressure, the faster burn time of T7 would raise the core pressure quickly and help get the AP going. A slower burn time would not raise the pressure as much so you would have to rely more on heat and flame propagation to get the party started.

But nothing speaks like your experience so I'm happy to use up my Pyrodex as a motor starter and save the T7 for ejection charges.

Great info and I hope the OP finds it all useful.


Tony
 

Onebadhawk

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Spot on Teddy.

While I cast my on pellets in 54's and up, I use a 1/2 pellet in 38's also. They are easily cut by pressing down with a single edge razor blade and rolling them, they pretty much snap in half after scoring them. I also glue my pellet in the top grain with Duco cement to prevent it from sliding down the stack, this is most beneficial when air-starting to resist the G's. 29's get a 1/2 pellet also but you have to carefully shave them down with a razor for fitment. I use a brass tube to push over them after rough shaving with the razor for a nice clean round pellet.
Hey that's a good idea John,, the brass tube to shave it round again..
I did forget to say,,
you don't want anything loose in the core as it's lighting
as it will try to exit the nozzle and if it's too big,,,, very bad.....
I find the 50 cal fits super tight in most ( not all ) 38 mm cores...
For the 54's the core is bigger so I take a notch out of the top grain and put the whole pellet in sideways....
On large motors I use a wood dowel and masking tape as many pellets to the top of the dowel
as you like with an e match under the tape as well...
I no it really doesn't matter,, but I always got a bit of a kick that by this method you can reliably
light 75 or 98mm loads with a single AA battery........

Teddy
 

emckee

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So with these methods, are you typically using a delay grain? If so, are you at all concerned about the pyrodex grain obstructing access to the delay grain (and thus lighting it), or are you just relying on the pyrodex grain to ignite the delay grain?

I'm thinking the latter would be the case, but since I haven't tried it, I wanted to ask if there were any concerns there.

Thanks! Very informative discussion!
-e
 

timbucktoo

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In my case, I am using a plugged motor so it's to primarily start motor but there is a smoke grain which needs to light off too.
 

Onebadhawk

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So with these methods, are you typically using a delay grain? If so, are you at all concerned about the pyrodex grain obstructing access to the delay grain (and thus lighting it), or are you just relying on the pyrodex grain to ignite the delay grain?

I'm thinking the latter would be the case, but since I haven't tried it, I wanted to ask if there were any concerns there.

Thanks! Very informative discussion!
-e
Yes,, there's been a delay grain in the loads...
I don't see any difference in the ignition...
Quicker if anything...
When I get the case back the delay grain is consumed....
No reason to believe anything different is happening when the button is pushed...

Teddy

Teddy
 

dshmel

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...
I find the 50 cal fits super tight in most ( not all ) 38 mm cores...
For the 54's the core is bigger so I take a notch out of the top grain and put the whole pellet in sideways....
...
Teddy
I do the same thing. I also use a half pellet in 29mm motors, especially Redline propellent, which seems to be hard to light sometimes.
 

Onebadhawk

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I do the same thing. I also use a half pellet in 29mm motors, especially Redline propellent, which seems to be hard to light sometimes.
For me the most difficult to light is any Mohave Green load Dwayne.....
I had "SteamPunk" over 30 lbs on the pad in Maryland with an Aerotech 75 / 5120 L 1390 G in it....
I put a homemade hand dipped ignitor in it the size of my thumb...
You could distinctly hear it when the ignitor went off,,,,, no joy.......
I couldn't believe it,,, my buddy Fred T took something out of his box and put it in the motor for me.....
He said something about that aughta light an ice cube on fire,,, lol...
Instant on.........lol...

Teddy
 

sharkbait

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So with these methods, are you typically using a delay grain? If so, are you at all concerned about the pyrodex grain obstructing access to the delay grain (and thus lighting it), or are you just relying on the pyrodex grain to ignite the delay grain?

I'm thinking the latter would be the case, but since I haven't tried it, I wanted to ask if there were any concerns there.


Thanks! Very informative discussion!
-e
Your pre-formed pellet or your cast in place pellet is at the top of the stack it will light both. If you ever took a CTI motor apart, this is very very similar to what they do.

My smoke/delay grains are a little different in that the bottom of the grain is the actual propellant to a depth equal to the grain web thickness, the remainder is smoke/delay. This helps keep the colors from getting contaminated by the smoke and also makes controlling smoke or delay timing much easier as the smoke/delay doesn't start burning until the actual motor burn out is complete.
 

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