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FFFFG Black Powder, Pryodex P (FFFG) and Triple 7

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edwardw

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What types of powder you you all use for charges? I cannot find any FFFFG BP in my town, but I have found some Pyrodex P, which is FFFG. I talked to a guy at the gun store and he said that Hogdon Triple Seven, while FFG burns hotter and more gas than Pyrodex FFFG. Anyone know anything about this? Currently I'm using Pyrodex P, calculating the FFFFG charge, then doubling it for use with Pyrodex P. Any thoughts help would be appreciated.

Edward
 

rstaff3

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This had been discussed in several threads, you can find them by searching the forum for pyrodex. I have run a couple of experiments with Pyrodex-P and it looks promising. The key is containment. Pyrodex and other similar powders burn well if contained (like in a gun), but doesn't tend to fully burn otherwise. What I and others have done is to use a pvc fitting, drill a hole for the ematch lead, seal the hole (I used hot melt glue), fill with powder as desired, cap it off with wadding, and then seal the end with vinyl electrical tape. Two pieces over the end in an 'x', and then a couple of wraps around the fitting.

The -P is required over the other types of pyrodex. Some other brands of fast burning powders may work as well (or better?)

This is probably repetitious with the other threads. Sorry I got carried away.

PS - this technique is not mine, I borrowed from J. Wickman. Others have had similar results.
 

UhClem

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There is no direct replacement for black powder.

Various people have reported using Pyrodex P with good results if the powder was properly confined. My results were not as good.

Based on <A HREF="http://www.pratthobbies.com/pyrotest.htm">a report from Pratt Hobbies</A> I built a charge using a centrifuge capsule and Pyrodex P. I then wrapped the capsule with electrical tape as recommended. The result of the test was that the shear pins (2 ea. 4-40 nylon screws) held. I repeated the test with the same volume (about 2 grams) of BP in my 6" L3 rocket and got a clean separation.

<A HREF="http://home.earthlink.net/~david.schultz/level3/t22/pictures/ejectiontest.jpg"> test picture</A>

When I performed this test on the drogue section, the Pyrodex charge did shear the 2-56 nylon screws but did not push the pieces apart. The BP charge did push everything apart.

I suppose that a larger charge of Pyrdodex would have worked but I didn't do any more tests because I was already completely filling the capsules. I might try again because I now have about a pound of Pyrodex P left over.
 

rstaff3

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In my testing the Pratt centrifuge container full of Pyrodex-P didn't even fully eject the chute from my 4" test rocket. A 3/4" PVC fitting full of worked well. One day I'll actually try a flight test.
 

firemanup

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Triple 7 worked ok for us in ground testing..

See my webpage and click on the ejection cannisters page to see more details...as was mentioned above a good wrap of tape is needed to get a full burn of the powder...
 

Johnnie

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Flight tests have worked with a 50/50 mix of Black powder and Pyrodex P, as well as straight Pyrodex P...while using Christmas tree light bulbs as ejection charges...you don't need a leup for no stinkin bulbs.

Like Rstaff has said, containment is the key, the longer you can keep it contained before it bursts, the more thorough it will burn, and produce the needed gases for ejection.
 

bobkrech

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Edward

In a black powder gun there is very little difference in the performance of any of these powders. The reason is that the powders are tightly confined by the wadded and rammed ball.

In a rocket there is a huge difference since the powder is generally not confined. BP in any grain size (FFFFg is the finest powder, FFFg less fine, FFg even coarser) are all the same chemical mixture of potassium nitrate, charcoal and sulfur. BP burns much faster than any of the BP substitutes, so when you simply replace BP with Pyrodex, Triple 7, etc. your rocket fizzles and crashes.

The reason is that the chemicals in Pyrodex and Triple 7 burn much slower than BP. A few grains ignite and simply blow away the bulk of the powder grains before they get hot enough to ignite. Finer grain powders burn faster because they have more surface area per unit weight. The finer grained BP substitutes have unconfined burning rates about 10 x lower than FFFFg BP, but the burning rate is proportional to pressure, so confining the powder at several hundred PSI gets it to burn at the same rate as unconfined BP.

The folks who have successfully used Pyrodex {and this means the finer grained P (pistol) verses the coarser grained R (rifle)} or Triple 7 confine it in a relatively strong container (a centrifuge tube, etc.) and packed with a wadding to eliminate free space. The container opening has several wraps of electrical tape or some other barrier material that will not rupture until several hundred PSI pressure is developed within the container. What ever you confine the substitute power, make sure the container doesn't fragment into a lot of high velocity particles.

Bob Krech
 

LarryH

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You could try the Pyrodex pellets, these are small self contained precompressed charges of 30 or 50 grains, they have quite a bit more "ommph" to them than the loose powder, and I've *heard* that they're great for blank loads, so they should burn pretty good in open spaces.
 

edwardw

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I looked at the pellets - they are just pellets with a central core in them, kind of like a propellant grain. They are uninhibited on all sides so when they go I bet they go fast.

Edward
 

Johnnie

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Actually, the pellets are very similar to pellets used to ignite Pro38 motors.

In EX motors here locally, the Pyrodex pellets were used to Light an AP grain in atmosphere, and ignition was instantaneous...

How many pellets would it take to eject a parachute payload?? worth looking into, but containment I think would still be an issue.
 
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Austin

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I have used 4Fg for all my BP needs. The stuff in Pro38's appears to be 3Fg and that will also work.

Carl
 

BlueNinja

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Do the Pyrodex pelltes require a LEUP to buy and store? There were some kind of pellets at walmart once, either pyrodex or 777.
 

rstaff3

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Yes, if you are using 4f to refer to black powder. All black powder, unless it is an integral part of an approved product (ie Estes motors, AT motors that are supplied with powder) OR is used in an antique firearm.

Pyrodex, 777 and the like are smokless powders and do not require a LEUP.
 

BlueNinja

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Sweet.... I might buy some pyrodex and see how it burns.
 

rstaff3

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If you get the Pyrodex brand, make sure you get the -P type. This is for pistols and burns faster. I have run two ejection tests. You can read about them on my web page thru the link in my sig.
 
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