november, 2002 issue 1/2 i.d. flying z-bombs.pyrobin.com › files › flying spinners.pdf ·...

Passfire

Volume 2, Issue 11

Build This...

1/2" I.D. Flying Z-Bombs.

Summary: This fun little piece can be turned out so quickly it falls under the category of "quick pyro fix." Z-bombs are spin stabilized flying devices with salute headings. While related to the spin stabilized rockets sold under the name of Stinger Missiles, they contain no nozzle or inner core. No spindle tooling or hollow drifts are required to make them, and the finished product is nothing more than a charged tube. Unlike a buzz bomb or tourbillion, they zip up to respectable altitudes!

November, 2002 Issue

Build This: 1/2" I.D. Z-Bombs

Design Notes: Mass Launching Z-bombs

Gallery: 4F 2002

Autopsy: 8" Ball Shell

Class C Corner: Wild Bombardment, Starry Night

Formula: Meal powder with 6% Ti or FeTi. Materials: Tools:

(1) 4" or 5" long 1/2" I.D. tube with strong wall. 1/2" taper tip rammer(1) 3"x5" piece of 70lb kraft for star bag heading 1/2" flat tip rammer(1) 1-1/2" roofing nail 1/2" ramming base (optional)(1) 4" square 3/4" thick plywood 1 tsp scoop(1) 2" segment of 1/16" visco or chinese fuse 1/2 tsp scoop

1/32" drill bit

9/64" drill bit

Unmeasured Materials: powdered clay, 1/4" stars, black match, glue.

Copyright © 2002-2005 Passfire Labs, LLC.

18 PM]file:///C|/Documents%20and%20Settings/Detrimental/My%2...0Spinners/half%20inch%20ID%20flying%20z%20bombs/p1.htm [6/24/2007 2:02:

http://www.passfire.com/_logout.asp

http://www.passfire.com/archives/issue7_1/issue7_1.asp

http://www.passfire.com/archives/archives.asp

http://www.passfire.com/formulas/formula.asp

http://www.passfire.com/reference/reference.asp

http://www.passfire.com/market/market.asp

http://www.passfire.com/board/board.asp

http://www.passfire.com/about/about.asp

http://www.passfire.com/archives/issue2_11/build2_11_1.asp

http://www.passfire.com/archives/issue2_11/design2_11_1.asp

http://www.passfire.com/archives/issue2_11/gallery2_11_1.asp

http://www.passfire.com/archives/issue2_11/autopsy2_11.asp

http://www.passfire.com/archives/issue2_11/ccorner2_11.asp

mailto:[email protected]

Passfire

Volume 2, Issue 11

1/2" I.D. Z-Bomb

Figure 1: Side and end views of Z-bomb components and thrust vectors.

Figure 2: Home made drift set for charging Z-bombs.

Introduction: Z-bombs are a type of spin stabilized flying device that have no fins, no stick and no venturi. They are quite compact and unassuming at first sight, but they can fly to surprising heights. These devices are probably more related to buzz bombs or tourbillions than rockets, since they rely on spin for stability during flight. They could also be described as stinger missiles (spin stabilized rockets) without the exhaust nozzle at the bottom. In fact, simply drilling a hole into the bottom plug is all it takes to convert a completed Z-bomb into a stinger missile.

Because Z-bombs do not have a strong downward thrust vector, they ascend more gradually than the lightning bolt ascent you get from a stinger missile. They tend to accelerate faster and thus fly higher than tourbillions are capable of, and they eliminate the need for the stick or wings that tourbillions require. They also create more of a buzz sound due to the high RPMs they achieve, since they spin around their long axis the way hummers or bees do.

Two opposing exhaust holes at one end of the case utilize a compound angle to provide both the spin and the downward thrust to send the tube skyward. Figure 1 shows the basic construction of the Z-bomb, along with the thrust vectors created by the angled, off-center holes.

Like most end burning spinners that utilize a side hole as an exhaust vent, a tapered clay plug is used at the vented end in order to prevent the exhaust gases from eroding the paper tube, which will increase the hole size and progressively reduce thrust during performance. Thus, a tapered rammer is needed for ramming the bottom plug.

Figure 2 shows the two rammers required to build Z-bombs. They can be easily made from 1/2" aluminum rod available in most hardware stores. The end of one rod must be tapered using a grinder or electric sander. The taper should be about 1/2" long, and should be finish sanded with emery cloth or other fine grit to remove the rough surface of the initial grinding. Failure to do this will cause the clay to grab into the grooves and make removing the rammer from the case difficult.

02:20 PM]file:///C|/Documents%20and%20Settings/Detrimental/M...inners/half%20inch%20ID%20flying%20z%20bombs/p2.htm (1 of 2) [6/24/2007 2:











Passfire

The aluminum rammers may be pounded on directly with a brass hammer, but this tends to flair the heads over time. I prefer to fix segments of 1-1/4" diameter oak dowel rods to the tops as a hammering surface. This preserves your tooling and also allows you to use a regular steel hammer if you want. The wooden heads are best fixed to the rods using brass pins or nails that run completely through the wood and metal rod. The use of any type of adhesive will likely not hold up under all the pounding.

The most difficult aspect of Z-bombs is getting them to launch correctly. If just placed on the ground, they will flip over on launch 50% of the time and turn into Ground Bloom Flowers. You can launch them out of tubes, but the flight path tends to be erratic. I've seen them come out of tubes at almost 90 degree angles!

The best way to launch Z-bombs is from a special launch pin similar to how stinger missiles are fired. I have modified the traditional Z-bomb design into two versions that utilize a launch pin. The first method is easier to make, but does not work as well as the second method. The smaller diameter launch pin in method #2 allows the device to spin more freely and rarely gives problems. The fat pin used in method #1 sometimes causes the Z-bomb to bind and get stuck on the pad.

More...





Passfire

Volume 2, Issue 11

1/2" I.D. Z-Bomb Page 3

Figure 3: Launch pad and Z-bomb construction used for method #1.

Figure 4: Raming base used for method #1.

Figure 5: Launch pad and Z-bomb construction used for method #2.

Figure 6: Raming base used for

Method #1: The simplest launch mechanism is shown in Figure 3. The bottom plug of the Z-bomb is inset by 1/2" so that the tube can slide onto the launching base. The launch pad and the ramming base are constructed almost identically, with the launch pin being about 1/8" shorter. To make the ramming base, a 1-1/4" segment of 1/2" diameter aluminum rod is pressure fit into a 3/4" thick wooden block drilled with a 15/32" diameter hole. Similarly, the launch pad is made with a 1-1/8" segment of rod pressed into a 3/4" thick piece of wood that is at least 4" square.

A 4" long tube is placed on the base and 1 tsp of powdered clay is rammed firmly using the tapered rammer. The case is then charged in 1 tsp increments of meal. Metals such as titanium, steel or ferro titanium can be added to the meal to give a better tail. Use between 6-10% metal by weight. When using metals in the fuel, the first increment should be just plain meal, since drilling through meal with metal in it can cause a spark hazard.

Once the case is charged to about a half inch from the top, a final increment of powdered clay is rammed in place. It is important that the case be test fitted on the launch pin at this point to be sure that it can rotate freely and easily slide on and off. There is often clay caked on the inside of the tube that must be removed. Sometimes the bottom lip of the case will flair out from compression during ramming and must be reamed open again. This is easily done using a segment of 3/4" dowel with a blunt taper on one end. Failure to properly prepare the tube in this way can result in it sticking on the pin during launch.

Method #2: The second method I devised for launching Z-bombs utilizes a smaller pin, which reduces friction and binding. This virtually eliminates problems with the Z-bomb sticking on the pad during launch. Figure 5 shows how a thick clay plug is used to create the launch pin cavity. This can be created using a special ramming base as seen in Figure 6, or the pin hole can be drilled using a drill press after the case is charged. If the hole will be drilled, then no ramming base is even required and the clay plug can be rammed flush with the end as seen in Figure 5. A 9/64" drill bit should be used if the launch pin is a 1/8" diameter nail.

Since drilling the pin hole adds an extra step, a ramming base that creates the hole is desireable. Figure 6 shows a typical home made wooden base with metal pins press fitted. The length of the 9/64" diameter pin is 1/2" above the nipple, and the 1/2" diameter nipple sticks out 1/4" above the base. Since the hole will not extend beyond the first clay increment, hollow ramming drifts are not required.

The only difference in loading this case compared with method #1 is that an












Passfire

method #2.

extra 1/2 tsp of clay is used for the plug, making a total of 1-1/2 tsp of clay.

More...





Passfire

Volume 2, Issue 11

1/2" I.D. Z-Bomb Page 4

Figure 7: Free-hand drilling of exhaust vents.

Figure 8: Guide block for drilling consistent compound angles.

Figure 9: Salute and star headings.

Drilling Exhaust Holes: Two 3/32" diameter holes with steep downward angles are drilled at opposing sides of the case. The need to be slightly off-center in order for the case to spin. Drilling the exhaust holes is the most critical and difficult step in making Z-bombs. The downward angle of the holes greatly effects the ascent rate and payload weight that a Z-bomb can carry.

This drilling can be done free-handed using a drill press as shown in Figure 7. The case is held with both hands at the approximate angle shown and pushed up into the spinning bit. Care must be taken to stop once the powder core is reached. You must also be careful to drill the correct end when using Method #1, since both ends will look exactly the same.

It is best to make a mark about 3/4" from the end to be drilled as the spot to begin drilling the hole. Since it is difficult to get a hole started at such a steep angle, begin by drilling slightly into the case straight on, then switch to the proper angle. This will create a dimple to keep the bit from sliding when once the case is angled down.

I'm sure determined readers will be able to drill the holes with a hand drill if that's all that is available. Regardless of how you drill the holes, a guide block as shown in Figure 8 can help with consistent hole placement and angle. The dimensions shown are for a 3/4" O.D. case where the bottom of the powder cavity sits 3/4" from the end of the case. The screw at the back of the hole is used to fine tune the position of the hole from the end of the tube. If the hole is drilled too far up, then it can enter the powder core above the clay plug and render the conical cavity useless.

Headings: Surprisingly, this little 1/2" I.D. Z-bomb can lift a payload of 5-8 grams of stars to a respectable height. If the heading will be stars, the Z-bomb case should be about 4" long. A salute heading should use a 5" long z-bomb case that is plugged 1" short from the top. The plugs in both types are vented with a 1/8" hole and fused with a short stick of black match.

Salute headings are simply charged with flash, followed by a wad of paper and sealed off with hot glue. Star headings are made by rolling two turns of 3" wide kraft paper around the end of the case so that 2" extends to form the star bag. About 1/4 tsp of 4FA black powder is poured in first, followed by some 1/4" stars. The top is folded down using a triangle fold and held down with tape or glue if necessary.

Fusing: These devices must be fused with a very small diameter fuse such as chinese firecracker type fuse or 1/16" diameter Visco fuse. The latter may be sold by some hobby suppliers for use as cross match, but it is ideal for use with Z-

file:///C|/Documents%20and%20Settings/Detrimental/M...inners/half%20inch%20ID%20flying%20z%20bombs/p4.htm (1 of 2) [6/24/2007 2:02:22 PM]










Passfire

bombs (although I don't recommend it for cross-match). The fuse is inserted into either one of the exhaust holes and held in place with a piece of tape.

While no two Z-bombs will fly the same way, they generally tend to go mostly upwards. If you bent the case during ramming, you will get an amusing cork-screw pattern. Longer Z-bombs can do other unexpected things, such as making unpredictable turns. This is definitely not a close proximity item, so use with discretion!


file:///C|/Documents%20and%20Settings/Detrimental/M...inners/half%20inch%20ID%20flying%20z%20bombs/p4.htm (2 of 2) [6/24/2007 2:02:22 PM]


Passfire

Volume 5, Issue 3

Build This...

3/4" I.D. Buzz Bomb

Summary:Buzz bombs are a type of tourbillion that contain a single port at one end, making them easier to produce and with a longer burn time than the traditional four port tourbillions. A variety of effects can be charged into the heading of buzz bombs, with the most common being report headings. The project described here uses a glitter gerb rammed into the end, which ignites at the same time as the tourbillion lifts, creating a nice dome of glitter. Since it is not possible to create glittering drivers strong enough to lift a buzz bomb or even a four port tourbillion, this device may leave knowledgeable pyro observers a bit puzzled.

June, 2005 Issue

Build This: 3/4" I.D. Buzz Bomb

Technique: Clay Rocket Nozzles

Tool Tip: Maltese Driver Ramming Tool

Autopsy: 8" Scatter Star Shell

Class C Corner: Alien Resurection

Formula: 3/4" I.D. Vertical Driver, Winokur Silver Gerb 'C' Materials: Tools:

(1) 40" long x 7-1/2" wide strip manila paper 3/4" taper head rammer(1) 7-1/2" long x 7-1/2" wide 30 lb kraft 3/4" flat head rammerBentonite + 30% grog or ground ceramic chips 40-50m brass mallet or ramming machineWhite glue + water 50/50 3/4" ramming baseThin black match 3/4" case formerFoil tape ScissorsHot glue Hot glue gunAluminum flashing Hammer & nail


37 PM]file:///C|/Documents%20and%20Settings/Detrimental/My%2...ners/three%20quarters%20inch%20ID%20buzz%20bomb/p1.htm [6/24/2007 2:02:










http://www.passfire.com/archives/issue5_3/technique5_3_1.asp

http://www.passfire.com/archives/issue5_3/tool5_3_1.asp

http://www.passfire.com/archives/issue5_3/autopsy5_3.asp

http://www.passfire.com/archives/issue5_3/ccorner5_3.asp


Passfire

Volume 5, Issue 3

3/4" I.D. Tourbillion... Page 2

Figure 1: Internal view of a buzz bomb with star burst header.

Figure 2: The tapered rammer, key to preventing exhaust hole erosion.

Introduction The Buzz Bomb is a modern version of the traditional tourbillion which has been simplified to use only a single exhaust hole. The device was actually invented in America and then later copied by the Chinese with items such as the Sunflower, Plane Flying at Night and many others.

There are two primary innovations in the buzz bomb design: the use of a conical end plug to prevent exhaust hole erosion and the use of propeller like wings to convert some of the rotary motion into upward thrust. The exhaust hole is drilled through the side of the casing toward the bottom, as seen in Figure 1. The hole must go through the clay plug as shown, which prevents the fire from burning the hole out and causing continually weaker thrust over time.

The 3/4" I.D. size shown here is actually unusually large for a buzz bomb, with 3/8" and 1/2" I.D.s being more common and easier to produce. The design is the same regardless of size, however, and the 3/8" size would be a good starting point for beginners. The fuel for the 3/8" size is simply ball milled meal with optional 5% metal dust added for different effects. The casing for a 3/8" I.D/ buzz bomb should be 3" to 4" long with a minimum wall thickness of 1/8".

The larger size shown here was chosen as a companion project to go with the Maltese Driver Rammer described here. The case, end plug formula and fuel is exactly the same as that used for the horizontal girandola drivers described in that article. This way you can use one machine to produce two distinctly different types of effects.

The Tube The first step to constructing a buzz bomb is to make or find a suitable tube that is strong enough to hold the high internal pressures and withstand the long burn time without burning through. The tube used here was made from three strips of manila file folder paper that total 40" in length. Two 14-1/2" strips plus an 11" strip that measure 7-1/2" wide were glued on one side using a mixture of water and white glue in a 50/50 ratio, then rolled around a 3/4" O.D. rod. A final two turns of 7-1/2" long x 7-1/2" wide 30 lb kraft is used to finish the casing. This will produce a final casing that is 7-1/2" long x 1-1/8" O.D. The rammer used to roll these casings was slightly over-sized in order to account for the tube ID shrinking as it dries. Both the rolling rod and the rammer were cut from the same bar in order to insure a matched size, then the diameter was increased on the rolling rod by wrapping three turns of thin plastic packing tape in parallel bands.

02:40 PM]file:///C|/Documents%20and%20Settings/Detrimental/M...s/three%20quarters%20inch%20ID%20buzz%20bomb/p2.htm (1 of 5) [6/24/2007 2:










http://www.passfire.com/archives/issue5_3/tool5_3_1.asp

Passfire

Figure 3: Passfire from ignition point to end burning color pot.

Figure 4: Foil taped used to protect passfire match.

Figure 5: Aluminum sheet with wing template.

The Plug Next you will need to create a special rammer to drive the bottom plug, which has a tapered end as shown in Figure 2. The exact angle is not important, just sand the end of a wooden dowel rod on a belt sander until it looks about like Figure 2. An aluminum rammer turned on a lathe would be even better if you are setup for doing that.

This is a high pressure driver, so you will need to use a strong end plug. The addition of a granular material such as grog or ground up ceramic shards in the 25 to 40 mesh range should be added to bentonite in a ratio of 1:3 for making the bottom plug. The top plug can be just plain old bentonite.

Start by pounding 3/4 TBSP of 1:3 grog/clay into the bottom of the tube using 10 to 12 solid hits on the tapered rammer with a brass mallet. Using rubber or plastic type mallets is inadequate and will result in blown plugs, so use a good solid non-sparking metal mallet. The plug can be rammed flush with the end of the case, but it is better if you make a small ramming base with about 1/4" of a nipple to insert the case onto. This will give your plug a better lock-in and also holds the case on center if you will be loading it using the driver ramming tool.

Important: immediately after the plug is rammed, use the rammer to measure where the bottom of the plug sits so that you can mark your drilling hole. The hole needs to be about 1/16" above where the bottom of the conical cavity sits inside the tube, so it is important to measure and mark this spot on the outside of the tube so that you know exactly where it is. If you are consistent with your clay measurement and ramming force, then the hole will tend to be in the same place every time, but it is good to mark it just to be sure.

The Fuel After the plug is rammed and marked, the fuel is charged in 1/2 TBSP increments, either by hand ramming or by using the Maltese ramming tool to considerably speed up the process. Granulating the fuel by dampening 20% with water and running through a window screen will make it much easier to work with when hand ramming, and is a necessary step when using the Maltese rammer.

The stopping point for your fuel charge will depend on the header effect you want. A final 1/2 TBSP of clay is used to plug the end, which will usually need a 1/8" passfire hole drilled through it.

The exhaust hole is now drilled at the mark you made on the side of the casing. A 3/16" hole will work well, but you may also be able to get away with an 11/64th hole to produce a little bit stronger thrust. If you blow a plug or pop the tube, drop back to the larger hole.

Because of the ceramic material in the plug, you don't want to use power when drilling through it. Drill through the case wall until you hit the clay, then turn the power off and hand twist the bit the rest of the way into the powder core.

The Header The traditional buzz bomb heading is a report, hence the "bomb" following the "buzz." This can be made by filling about an inch of


Passfire

Figure 6: Slotting the tabbed support wings.

Figure 7: Folding tabs down over the leading edge of the wing.

empty tube space above the end plug with flash, then closing with a wad of paper followed by hot glue. An alternate method is to insert a small hand-rolled salute into the cavity and gluing it in place, although this is a bit more work to create the same effect. In both cases you will need to drill a passfire hole through the clay end plug and insert a stick of black match into it.

This 3/4" size device actually has enough room inside the tube to load a respectable amount of small stars if you would rather make a color heading. Figure 1 shows such a heading of stars, which really don't even need a burst charge because the centrifugal force of the spinning tube will throw them out. So just leave out the burst charge and cram as many stars as you can fit into the tube!

Another type of experimental heading, which I have not worked the bugs out of yet at the time of this writing, is to charge the top portion of the tube with an alternate effect like a glitter or color pot that ignites at the same time as the buzz bomb takes flight. A stick of black match is run from the ignition point up to the top of the case as seen in Figure 3, which is then enclosed with a long piece of foil tape so that both ends ignite instantly. The idea is to have rising effects that are not easy to produce with the driver fuel, such as color, glitter, color changes and other seldom seen effects. However, some of the problems that plague this method result from the high RPMs of the spinning tube either blowing out the fire or throwing it from the tube so that the flame front is lost and the effect stops burning during flight. This paragraph will be updated when this problem is solved.

The Wing The original buzz bomb featured a plastic wing, while the Chinese adaptations use a paper wing. Paper wings are easy enough to produce, but they tend to be too flimsy in larger sizes such as this device. I have opted for an aluminum wing that is made using the same pattern the Chinese developed for their paper wings. It can be produced by using your computer to print this wing template pattern onto a sheet of Avery 8.5 x 11 full page size adhesive label, which will give you three patterns per sheet. You can also use an image editing program to scale this template for different size buzz bombs. You may need to scale the image anyway even for this project if it doesn't print to the correct size. Trying to get images to print at the correct size on different printers can be problematic. The distance between the wing tips measured across the length of the paper should be about 9-7/8" when scaled correctly.

The wing patterns are cut from the adhesive label and then fixed to a sheet of thin aluminum flashing. The label and the scrap of aluminum can be seen in Figure 5. This aluminum is so thin that you can cut it with scissors just like paper, using the fixed template sticker as a guide. Once cut out, the label is peeled off and discarded.

Next you will want to make a series of cuts half way through the thin strips next to each wing, as seen in Figure 6. These will form tabs that you fold over to lock the wing pieces together. The tube is weaved between the slots in the wing such that the wide cross pieces is on top (Figure 10) while the two thinner cross pieces are on the back side (Figure 11). This part can be tricky to describe, as you need to twist the wings while trying to bend the metal around the


http://www.passfire.com/archives/issue5_3/buzzbomb_wing.jpg

Passfire

Figure 8: Punching holes through the tabs to lock them in place.

Figure 9: Proper angle of exhaust hole relative to wing plane.

Figure 10: Gluing the wing to the engine.

driver tube, keeping the flapped pieces on the back side of each wing. When everything starts to align properly, fold the tabs over to lock the back piece to the top piece, as shown in Figure 7. If you were making a paper wing, you would use glue and staples to hold these together.

The folded tabs will not stay put without "riveting" them together as seen in Figure 8. You have to hold them in place while driving a center punch or nail through each tab so that it pins it to the underlying wing. Make sure the wing is correctly wrapped around the tube before riveting them together, since they will no longer be able to slide into place after you nail them down.

The finished wing should be twisted like a propeller such that the tabbed ends are angled upward. The casing is then rotated so that the exhaust hole will spin the tube in the correct direction to give it lift. Since the wing can also be installed "upside down" relative to the images shown here, it is important to pay attention to the desired direction of rotation. For the orientation shown in Figure 10, the tube will need to spin clockwise. If your riveted edges are reversed from that in Figure 10, it will need to spin counter clockwise.

The last step is to hot glue your wing to the engine, which is done by squirting hot glue into the cracks along the edges as seen in Figure 10. Before applying the glue, the engine will need to be properly rotated so that the exhaust hole is angled down at 45 degrees to the horizon, as seen in Figure 9. This way the engine provides both spin and downward thrust to aid with flight. If fact, the buzz bomb will still fly with just a straight stick attached in place of a wing, as seen in Figure 9. However, it will not fly very high and will tend to drift sideways a considerable distance. Given that this is basically a flame throwing buzz saw flying around without a blade guard, it is very preferable that it goes straight up rather than coming after you!

Usage Buzz bombs are placed flat on a smooth surface with the exhaust hole facing down. They can be launched from asphalt, but usually not grass or bumpy turf that prevents them from spinning well. A good clearing is required as the flight path is often unpredictable, just like their big brother-- the girandola!


Passfire

Figure 11: Bottom view of the wing.

Figure 12: The completed buzz bomb.




Passfire

Volume 1, Issue 1

Build This...

Materials: (2) 7" x 1/8" thick wood slats (1) 3/4" long segment of 5/8" dowel rod (4) 5" long x 1/2" I.D. x 3/4" O.D. parallel wound tubes (8) 5" long segments of 22 gauge wire (2) 9-1/2" long segments of match pipe (4) 10-1/2" long sticks of black match (only 2 pieces if match is thick) (8) 3/4" pieces of 4-strand cross match type black match (4) 5" x 3" sheets of 30lb kraft Powdered Clay, string, slurry prime, meal powder, wood glue, aluminum tape

Compositions: Gold 1/2" Driver, Meal, Flash

Tools: Hammer, 1/2" flat rammer, 1/2" tapered rammer, 7/64" drill bit, wire cutters, needle nose pliers, scissors, anvil cutters.

More...

October, 2001 Issue

Build This: Learn how to make the quad tourbillion.

Autopsy: Take a peek inside a Lidu 6" crossing rings w/bowtie shell.

Technique: Learn how to spike your shells with the off-center method.


2:02:03 PM]file:///C|/Documents%20and%20Settings/Detrimental/My%20Do...torials/Flying%20Spinners/4%20driver%20tourbillion/p1.htm [6/24/2007









http://www.passfire.com/archives/issue1_1/build_this_1.asp



http://www.passfire.com/archives/issue1_1/autopsy.asp

http://www.passfire.com/archives/issue1_1/autopsy.asp

http://www.passfire.com/archives/issue1_1/off_center.asp

http://www.passfire.com/archives/issue1_1/off_center.asp


Passfire

Volume 1, Issue 1

Building the 4 x Drive Tourbillion... Page 2

Figure 1: Driver Details

Figure 2: Exhaust Orientation

Introduction: The quad tourbillion consists of a simple frame around which four single tourbillion drivers are arranged. They can be launched from sticks that have metal pins protruding from the end that fit into a small hole in the center of the tourbillion wheel. They may also be launched directly from the ground if the surface is smooth enough. The exhaust from each driver is positioned so that there is a 45 degree offset from the directly downward position, which enables each driver to provide both upward thrust as well as horizontal spin. The result is a thick umbrella shaped plume of sparks that slowly rise to about 100 feet in the air.

Making the Frame: The frame for this device is made by simply gluing two 1/8" x 3/4" strips of wood that are each 7" long so that they cross at their center. I prefer to use poplar, but any dry and light wood will do. It is easiest to use a band saw to rip the strips from standard 3/4" thick stock. A 3/4" segment of 5/8" dia dowel rod is then glued on its end at the center of the hub. This is clamped and allowed to dry. If the tourbillion is to be fired from a stick, then a hole must be drilled down the center of the hub that is slightly larger than the launch pin, which is usually around 1/8" in diameter.

Loading the Drivers: The key to successful tourbillion drivers is the use of a conical clay plug at the exhaust end of the tube. The purpose of this type of plug is to protect the exhaust hole from enlarging due to burn-through during flight, which will cause the tourbillion to slow down and even fall back to the ground. With the clay being between the paper tube wall and the burning fuel inside, burn-through is not a problem.

The conical plug is made with a special rammer that has a tapered end to it. The dimensions of this taper are not critical, so long as it produces a deep enough cavity for the exhaust hole to be protected. One issue with using tapered rammers is the increased tendancy for the bottom of the case to expand and rupture during loading. There are several methods to dealing with this problem:

�❍ Use high quality tubes made from virgin kraft.�❍ Use a sleeve that clamps onto the bottom of the tube to prevent bulging.�❍ Use lesser quality tubes rolled in Minwax Wood Hardener to strengthen them.�❍ Ram the first clay increment with a flat rammer and then ram the conical plug on top of that.

Once a method of preventing end splitting has been selected, the first step is to ram in the clay plug. This should be done using a single increment of clay (fire clay or bentonite) such that there is at least 3/16" of clay between the point of the tapered rammer and the bottom of the tube. There is no need for a ramming base and the case can be loaded flat on your ramming block. It is a good idea to load the clay plug in all the tubes before charging them, since this reduces possible errors from switching between rammer types, clay and comp.

007 2:02:04 PM]file:///C|/Documents%20and%20Settings/Detrimental/My%2...ials/Flying%20Spinners/4%20driver%20tourbillion/p2.htm (1 of 2) [6/24/2











Passfire

The remainder of the driver will now be rammed with a normal flat ended rammer. It is first necessary to load an increment of meal powder in order to prevent the hazard of drilling into a composition containing ferro-titanium when making the exhaust vent. The first increment of driver comp can be loaded on top of the meal before ramming. The driver comp should be rammed such that it takes about five increments to load the tube to within 1-1/2" of the top of the case. Scribing a line on your rammer at the 1-1/2" mark helps to know when the case has been loaded to the proper height.

Once the driver comp is rammed to within 1-1/2" of the top of the case, another small amount of meal is added, followed by the clay plug. Again, the meal is added to prevent drilling into the driver comp when making the passfire hole into the flash chamber. Some builders will omit the clay plug and just load lose flash over the last driver increment, but this method results in shorter and inconsistent burn times due to the powder blowing through as the flame progression nears the end of the tube. Driver comp does not grip the case walls as well as clay does, and it does not seem worth sacrificing 10% of driver burn-time for the sake of not having to ram a clay plug. Not using a clay plug will also result in the drivers not hitting their salutes at roughly the same time. The first salute that bursts will blow the frame apart and send the other drivers flying while they still burn. This is a nice effect when all drivers explode within a few seconds of each other, but not if one goes long before the others.

More...





Passfire

Volume 1, Issue 1

Building the 4 x Drive Tourbillion... Page 3

Figure 3: Ready to Assemble

Figure 4: Quickmatch Coupling

Figure 5: Completed Matching

Finishing the Drivers: Once all four drivers are loaded and plugged, the holes for both the exhaust and passfire must be drilled. This is easiest to do with a drill press on the lowest speed setting, using a 7/64" bit for both holes. The exhaust hole should be made about 3/8" from the end of the case containing the conical plug, and should be perpendicular to the case. When drilling, you should first see powdered clay removed by the bit, followed by black powder. When drilling the passfire hole, be sure not to drill to far beyond the clay plug to avoid the risk of drilling into the Fe/Ti driver mixture.

When all holes are drilled, a piece of 3/4" black match is inserted into each one. A pair of needle nose pliers or tweezers will assist in inserting the passfire match. Next the flash chambers are filled to withing a 1/2" from the top of the case with flash powder. It may be a good idea to leave out the flash until a few trials have been conducted so that you will not risk being in close proximity of the salutes should the tourbillion fail to gain enough altitude. Once the flash is loaded, a 1/2" paper end plug is pushed into the top of the case and sealed with hot glue.

Next prepare a meal slurry to apply around the black match protruding from the exhaust hole. This is to ensure that the driver takes fire from the burst of sparks that shoot from the quick match. When the prime is dry, use anvil cutters to trim the black match down close to the level of the prime.

Attaching the Drivers: Now that the hard part is done you are ready to put it all together. First the drivers must be attached to the frame so that the exhaust jet is facing the same direction on each arm. With the dowel rod marking the part of the frame that faces downward on launching, use the wire pieces to fasten the first two drivers so that the report ends butt up against the piece of wood that crosses the piece you are attaching them to. Be sure to angle the driver exhaust about 45 degrees from the vertical position. The next two drivers will actually go on the other side of the frame so that they can butt up against the other cross piece. Verify that all driver exhaust jets are aimed in the same direction by rotating the wheel and looking at each driver as it passes by.

Matching and Nosing the Drivers: Place a piece of match pipe so that it reaches from one primed jet to the other across two in-line drivers. Mark the midpoint of the pipe and use a paper hole puncher to notch a hole at this point. This whole will allow the fusing between the two matches that cross over each other. Place two sticks of black match in the pipe and use a clove hitch knot to fasten it to both driver ends so that the match sticks fork around the primed fuses.

Place the remaining match pipe between the opposite driver pair and notch a











Passfire

Figure 6: Applying Nosing Paper

hole where it crosses over the first hole. Insert the two match sticks and tie one end to a driver like before. Before tying to the last driver, insert a small piece of black match so that it connects between the two holes as shown in Figure 4. Also insert a piece of visco into one of the two holes at this time and secure with a piece of foil tape. Tie down the last piece of piped match and you should have something that looks like Figure 5.

The last step is to apply the nosing paper around the ends of each driver in order to protect the primed areas and provide a bucket to catch the match fire. Just over one turn of 30lb kraft is wrapped around the segment of driver that extends beyond the frame. The paper that overhangs the end of the driver is twisted like a candy wrapper to close it off, as shown in Figure 6.

At this point the tourbillion is finished and ready to fire. It may be launched by placing the dowel end down on a smooth surface like plywood or metal, or a launching stick can be made by inserting a nail or thin metal rod into the top of a 5/8" dowel rod that is inserted a few feet into the ground.


