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Garrace

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I have a 2.6 Fiberglas Tomach dual deploy that I am going to attempt level 1 the end of the month. My problem is with the black powder charge. I am attempting ground test on the nose. I started with .9 g of fffg black powder that I have had for a very long time and I am using miniature Christmas light bulb igniters(found how to make on web no electric matches were available ) tested with shear pins and had no ejection at all. Took shear pins out and tried 1 g. Nose popped off but just a couple of inches. From all the formulas it looked to me that that should have been enough powder so I figured the powder was too old. Went to Cabelas but can't get old powder so they sold me Pyrodex P FFFG substitute . Tried 1 g but no egection looked like it just burns but no explosion. Is this not the right powder or what am I missing. For my level 1 I am actually planning on putting the main in the booster with motor ejection backup and drogue in nose just to test DD without the worry of no main.
 

Garrace

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I am using heat shrink tubing on the bulb putting powder in then wadding. I must not be packing it tight enough for the Pyrodex and maybe I just need to try a bigger charge with the old powder
 

djs

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Probably need a bigger charge, and for Pyrodex you'll need much more than the FFFFG stuff. Where are you located? Someone near you might be able to point you to a source of "the good stuff". Also, are you using shear pins on the nosecone?
 

Garrace

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I'm in Olympia wa . I am planning on shear pins. I might go back to the old black powder I have an try 1.5 grams. What could go wrong.lol
 

DavidMcCann

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I use 1.5 grams of ffff in my 2.6" screech. I put it in vials, and fill the empty space tightly with wadding, then tape the lid closed. It's gotta be tight.

Pyrodex is very different. I'd keep trying the BP
 

MikeyDSlagle

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I use 1.5g of BP in my 2.6" scratch built level 1 bird. I use one #2 sheer pin holding the nose. During ground testing 1g gave more separation on a few tests. How you pack the laundry effects it too.

Pyrodex isn't a great substitute for what we use it for, needs more containment.

Drogue on top is more susceptible to tangling, so I understand. I'd recommend doing traditional DD with the main up top. Drogueless is less prone to tangling as well. Unless you plan to shoot the moon on your cert flight get your level 1 then play around with DD. I did electronic deploy with motor backup for my cert flight. But it's your flight, go as complicated as you want. Dual deploy in itself is nothing to be scared of though. Just take your time prepping and all will be well.

Mikey D
 

Garrace

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I'm using H180w so it should be about 1500' didn't think about the tangle issue maybe I will just do the main with motor back up and won't put a charge in the nose. Don't want to get too complicated
 

MikeyDSlagle

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Thanks 1.5 g of the old black powder worked great.
Thanks again for all the help
Good deal. My BP is FFFG and VERY old. But it has been kept dry and cool and it works just fine.

1500' is still very visible. Mine simmed to 1580' but only reached 1240' on a AT 38/240 H123W. Pad weight of 4.4 lbs. The Tomach is a bit less draggy than mine so you should be close to your altitude. What is your final build weight? It may not go as high as expected. Does it have a 29mm hole or are you adapting down for the H180W? Just curious.

I would imagine the rocket could survive a tangle and crash..well, depends on what it lands on I guess. But you would fail your cert and have to try again.

I use aluminum tubing and rifle brass for my charge wells. Put in the powder and started, cram a bit of dog barf in to pack it, tape it and it's ready to go. I was able to make some lighters with the Christmas lights but gave up on that and just bought some E-matches.

I have yet to see a drogueless tangle, but I have seen a few with drogues tangle. YMMV or course, and I haven't been at it all that long. Packing the laundry plays a big part as well, practice that and find you a technique.

Mikey D
 

wjmoser

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Try Muzzleloaders Supply in Puyallup, WA. Picked up a pound of Goex 4F there last year. I'd call ahead and make sure it's in stock.

I'm in Olympia wa . I am planning on shear pins. I might go back to the old black powder I have an try 1.5 grams. What could go wrong.lol
 

Garrace

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I am using a 29/38 adapter rocket weighs 66oz ready to fly. Hopefully it will quit raining so I can get some flying done. What size of main did you use? Tomach came with 30" and 14" drogue but if I m not using a drogue should I go up to a 36"?
 

MikeyDSlagle

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I use a 36" main. Landing speed is around 24 fps. It seems a little fast to me but the recovery area is unplanted ag fields. So it lands in soft dirt and doesn't drift very far. I plan to upgrade to a larger chute, just haven't done it yet.

Depending on the surface it lands, 30" may get the job done. What does your sim show as landing speed? I can never get my sims right. My landing speed shows 20 fps when in reality it is 24 fps. My first dual deploy flight simmed to 2326 feet and went 2419, was pretty close on that. Wind speeds, atmospheric pressure, humidity all come into play I suppose. I came into HPR same as you. Looking at putting the drogue up top and the main in the bottom. After watching a few flights and seeing how things lay out in descent, I came to the conclusion that drogue down low would be better. On my first dual deploy flight I took my drogue out literally just a few minutes before I went to the pad. Worked great. Some fall faster under drogue than drogueless. Depends on the rocket really. Someone with the Tomach should be able to help on that.


My Tyrannosaur will likely get a drogue, haven't decided yet. I'll consult the more knowledgeable folks at the launch when I am ready to fly it.

Here is some of the data from the Altimeter 3 of my first DD flight on an AT I245 Mojave Green:

Duration1 minute
Thrust time1.25 seconds
Max speed335 Mph
Peak accel20.68 Gs
Avg accel12.18 Gs
Ejection altitude2419 feet
Initial descent72 fps
Landing speed24 fps

And the graph:
FlightGraph.jpg

And a picture before the last decals were applied:
danger close u3.jpg

Looking at the fins will show you why mine has more drag than yours. And they probably help it stay flat during descent.

Mikey D
 

soopirV

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Seems like this has been solved, but wanted to say that I use Hodgon 777 with good success...as stated earlier, containment and quick ignition make this possible. I experimented in the beginning with 1ohm SMD resistor chip initiators as reported somewhere on the internets. I had a dismal success rate on the ground. When I switched to true eMatches, that rate went to 100% (assuming I had the right amount of powder, meaning I never had a smolder event, always went POP, just not always enough to get the job done while working out the right charge size).
 

Igotnothing

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Pyrodex P is an excellent replacement for the harder to get BP ffff. You just have to use it like it was intended. It is intended to propell a bullet down a tight fitting barrel. It needs resistance. It needs back pressure, so to speak.
Do not use metal tubes unless you carefully round the edges so they will not cut through wire insulation and short the s ematch. Do use cpvc tube and caps.

Cut a 3" to ???" length of 1/2" cpvc tube. Plug the end with epoxy. Mount the plugged end in a cpvc cap fastened to your bulkhead. Insert the ematch and bend the wire over the top edge. Tape the wire down against the outside of the body somewhere. Add a gram of P. Should be more than enough to shear a couple of 2-56 pins in a 2.6" tube and send the cone down range. Stuff the length of the tube with dog barf gently ramming it like a muzzle loading gun. Be careful not to smash the ematch. Tape over the end of the barrel so no dog barf or powder can fall out.
This is a gun that shoots high velocity dog barf so be careful. Wear eye protection when handling these. Never allow it to point at anything except your chute fire blanket.
Test. Should go "bang" not "shshshsh".
Move up to 3/4" cpvc when your rocket is big. I have done this up to 6 grams of Pyrodex P to overcome the 50 pounds of friction fit on a big nose cone in a huge, empty tube.

For small airframes where the bulkhead is too small to mount a 1/2" cpvc cap:
Hot melt glue an ematch in one end of a 2 to 3" piece of 1/4 Tygon tubing. Add 1/2 gram of P or BP. This is a lot for a small rocket. Fill remaining space with dog barf. Hot melt glue the other end.
This charge will make a decided "snap" - even with PyrodexRG rifle powder because it has no where to go and will burst the Tygon with pressure. Any glue that sticks well to the Tygon will work. Duco Cement works. Just be sure to seal up the ends well.
 
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Tim51

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Pyrodex P is an excellent replacement for the harder to get BP ffff. You just have to use it like it was intended. It is intended to propell a bullet down a tight fitting barrel. It needs resistance. It needs back pressure, so to speak.
Do not use metal tubes unless you carefully round the edges so they will not cut through wire insulation and short the s ematch. Do use cpvc tube and caps.

Cut a 3" to ???" length of 1/2" cpvc tube. Plug the end with epoxy. Mount the plugged end in a cpvc cap fastened to your bulkhead. Insert the ematch and bend the wire over the top edge. Tape the wire down against the outside of the body somewhere. Add a gram of P. Should be more than enough to shear a couple of 2-56 pins in a 2.6" tube and send the cone down range. Stuff the length of the tube with dog barf gently ramming it like a muzzle loading gun. Be careful not to smash the ematch. Tape over the end of the barrel so no dog barf or powder can fall out.
This is a gun that shoots high velocity dog barf so be careful. Wear eye protection when handling these. Never allow it to point at anything except your chute fire blanket.
Test. Should go "bang" not "shshshsh".
Move up to 3/4" cpvc when your rocket is big. I have done this up to 6 grams of Pyrodex P to overcome the 50 pounds of friction fit on a big nose cone in a huge, empty tube.

For small airframes where the bulkhead is too small to mount a 1/2" cpvc cap:
Hot melt glue an ematch in one end of a 2 to 3" piece of 1/4 Tygon tubing. Add 1/2 gram of P or BP. This is a lot for a small rocket. Fill remaining space with dog barf. Hot melt glue the other end.
This charge will make a decided "snap" - even with PyrodexRG rifle powder because it has no where to go and will burst the Tygon with pressure. Any glue that sticks well to the Tygon will work. Duco Cement works. Just be sure to seal up the ends well.
Thanks for the detailed description. So far I've not used Pyrodex, only FFFF BP, but would like the option 'if...'etc. So using your method, would you say there is any difference weight for weight between Pyrodex and FFFF BP? For example, is 1g Pyrodex tampered as you describe, equal to the same amount of FFFF BP?
 

MikeyDSlagle

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Thanks for the detailed description. So far I've not used Pyrodex, only FFFF BP, but would like the option 'if...'etc. So using your method, would you say there is any difference weight for weight between Pyrodex and FFFF BP? For example, is 1g Pyrodex tampered as you describe, equal to the same amount of FFFF BP?
Mass is constant. It doesn't matter what your are measuring. 1g is 1g. :wink: I know that is not what you meant. But I had to say it anyway. I'm sure someone will chime in about the speed of light and all kinds of theories, but it was a joke anyway.

Pyrodex P is supposed to produce the same energy as an identical VOLUME of FFFg (3F) black powder. Pyrodex has less mass than black powder of equal volume. So 1g of Pyrodex P should be more energetic than 1g of 3F, Triple Se7en is the lightest and most energetic...I think. Black powder measures throw volumes of known weights. So if you are using a powder measure with the grain tic marks, you can use the same amount of Pyrodex P, and I think Triple Se7en FFFg as 3F BP. If you weigh your BP, then you will need to adjust accordingly. For some reason 75% sticks in my head. If you have equal volumes of Pyrodex P and 3F BP, then the Pyrodex will weigh 75% of what the 3F weighs. I may be wrong on that, it's been years since I considered a BP substitute. Pyrodex can also be compressed more, or tamped down tighter, so you could put more in a smaller area than BP.

As I said above, Pyrodex P is a substitute for FFFg black powder. The more Fs, the smaller the grains and the more energy in a same weight. So Pyrodex P and FFFFg are probably pretty darn close pound for pound, or gram for gram. If I had to find a substitute for good ole "Holy Black", I would lean toward Triple Se7en. I think it is cleaner. Seems Pyrodex was harder to ignite as well. Which is why they have magnum primers and caps or whatever all they have.

I think Pyrodex has a shorter shelf life than black powder. It seems to be more hygroscopic. So, once opened, it will absorb more moisture from the air. How long til it is unusuable? No idea. Can always store it with a desiccant if need be.

The whole thing about the metal charge canisters cutting through the insulation is...well to be nice I will say overly-cautious. You can hold your wire straight up and pack around it, then wrap your tape and bend the wire over. I don't even do that, just bend over and tape. I use aluminum tubing, spent rifle/pistol brass and copper. Cut it, smooth it and you're G2G.

Mikey D
 
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OverTheTop

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I use FFFg in a 54mm Tomach. Two shear pins on the NC, M3 nylon screws drilled out with 1.2mm hole in the middle. The charge canisters were sized to hold the 2.5ml centrifuge vials. The canisters direct the blast axially in the airframe. I can't find my doco about how much charge I loaded, but I seem to remember 1.2g and 2.0g. I use the 1ml=1g equivalence and just measure by volume.
MotorMountAndChargeCanistersresize.JPG
The canisters reside inside the avionics bay.

I like that rocket. Mach 1.8 and 21500' :)
 
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Tim51

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Mass is constant. It doesn't matter what your are measuring. 1g is 1g.
:facepalm: I'll get my coat.. (and whilst I'm doing that try to figure out whether a ton of feathers weighs less than a ton of lead..:eek:)
 

Garrace

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Just a quick update and thanks for everybody's help. As a lot of you mentioned containment is the key. I have had success with either black powder or Pyrodex as long as it is tightly contained other wise it just flashes and burns with no pop. I currently use 1/2 pvcc pipe with one end epoxied closed I did order some electric matches from one of your suggestions but they haven't arrived yet but I did epoxy Christmas light socket in the bottom of some and used my modified Christmas light (little tricky to plug in down in the pipe) poured in powder charge ,packed dog barf and taped the end. Worked fine with either powder. One further note I did get my original Christmas light with heat shrink to work as long as I taped the crap out of them but the pipe is easier and more reliable.
thanks again
 

Igotnothing

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As MikeyD said, " Mass is constant" - and then we go to measure weight on a scale. This is the difference between truth and usable info.

Those little plastic canisters that Over The Top showed in his picture, (and come with Aerotech reloads) are marked on the side for Volume / cc's - which if you were weighing water would be grams. You want a x gram Volume of powder. Cause keeping a little scale with you is harder than keeping a few of those little centrifuge canisters in your kit.

And isn't OTT Aussie? Wouldn't that be 'Over the Bottom"? Anyways, that is why his centrifuge cannisters have lids attached. So the powder doesn't pour out.

Used Christmas lightbulbs for a while, but the elements are too fragile for my ham-fisted efforts. Was only getting about a 50% success rate on continuity at the end of assembly. So I just pay for ematches.

Always rotate your ematch stock and test-to-failure the oldest one prior to a launch if it has been a while. The pyrogen can see deterioration over time.
 
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Garrace

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Is there any problem with making the charges ahead of time with the ematches ? I m talking like a couple of weeks. I didn't know if they would deteriorate in contact with the powder
 

OverTheTop

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Is there any problem with making the charges ahead of time with the ematches ? I m talking like a couple of weeks. I didn't know if they would deteriorate in contact with the powder
I have used them successfully months after putting them together. No problems noted by me.
 

Steve Shannon

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Is there any problem with making the charges ahead of time with the ematches ? I m talking like a couple of weeks. I didn't know if they would deteriorate in contact with the powder
The big problem is that it makes it difficult to test continuity safely at your table when prepping. You don't want to test continuity with powder until you're at the pad or a special preparation area away from others.
 

OverTheTop

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Once the rocket has powder in the charge wells I treat it like a gun and never point it at anyone. Safety first!

It is armed on the pad and checked for continuity then (by beeps or telemetry).
 

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The big problem is that it makes it difficult to test continuity safely at your table when prepping. You don't want to test continuity with powder until you're at the pad or a special preparation area away from others.
I test continuity before I prep the charge!
 

Igotnothing

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May I encourage everyone to get a cheap face shield from Harbor Freight and wear it religiously when handling charges and assembling rockets at the bench or pad. I had a 3 gram charge go off while doing final bench assembly. Power was hooked up but off. Made metal contact on a comm port and bang. The cpvc charge tube was tightly packed and fractured. I was well protected except just a t-shirt over the soft underbelly- which is of course where the fragment of plastic struck me. Stung a bit. Left a mark in spite of the copious man fur.
Only damage other than the tube was the fancy electronics. The board is dead.
 

rstaff3

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I wouldn't use the Pyrodex unless you want to just to say you did. I have successfully used 3/4" pvc fittings as the wells for Pyrodex P. Electrical tape in two directions over the top and then wraps around the fitting. If you use PVC, you run the risk of blowing it through the body tube unless it is contained in some other holder or fitting.
 

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As MikeyD said, " Mass is constant" - and then we go to measure weight on a scale. This is the difference between truth and usable info.

Those little plastic canisters that Over The Top showed in his picture, (and come with Aerotech reloads) are marked on the side for Volume / cc's - which if you were weighing water would be grams. You want a x gram Volume of powder. Cause keeping a little scale with you is harder than keeping a few of those little centrifuge canisters in your kit.

And isn't OTT Aussie? Wouldn't that be 'Over the Bottom"? Anyways, that is why his centrifuge cannisters have lids attached. So the powder doesn't pour out.

Used Christmas lightbulbs for a while, but the elements are too fragile for my ham-fisted efforts. Was only getting about a 50% success rate on continuity at the end of assembly. So I just pay for ematches.

Always rotate your ematch stock and test-to-failure the oldest one prior to a launch if it has been a while. The pyrogen can see deterioration over time.
I did my L1 with full DD on a scratch built rocket. I was more worried about the motor assembly, it was my first Loki motor, then the DD and altimeter. That was because I ground tested the s**t out of it. I had more direct lit ejection and altimeter lit ejections using vacuum on the av-bay then I want to count. By the time I was done with all of that, the altimeter and DD was not a worry. I used xmas tree bulbs for all of my test. I broke the bulbs, pulled the wrapped wire off the base of the filament wires, and soldered two bulbs parallel to increase the odds of a successful deployment. That wire that is wrapped around the base filament wires in the xmas bulb is what allows the string of bulbs to stay lit when one burns out. It bypasses the filament. You want to remove that so only the filament can be tested with an ohm meter. After testing each bulb, I solder two together and tested again. The resistance should read half of what either of the single bulbs were. I then wrapped them in a 3" wide piece of kraft paper and hot glued them into the bottom of the tube. The 3F BP was poured in, the tube folded over and taped closed. This worked great.

After I started using electric matches, I laid the match on a piece of duct tape, started folding it lengthwise, poured the BP over the match and finished folding the tape to seal everything inside. This was not tight containment and worked perfectly with 4F BP. I doubt it would work at all with BP substitutes.

My suggestion is that since you have the experience with the altimeter and making charges, keep it simple, do what you've learned, set it up for standard DD and fly the cert.
 
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