3 Stage Strobe Rocket
Camila Fonua
Yeah Col,
I have worm respirators in the past for many things including pyro but I don't worry too much about it anymore, I hate them, That's one of the reasons I bound that batch with NC to help capture the dichromate better so I don't breath it as much while pressing.
Strobe fuel can very finicky to get that primo popping. Some people resort to mixing in a little magnesium powder to get things a little hotter. It tends to be easier than trying to source different alloys of MgAl. It can be a very frustrating experience dialing them in from what I've heard. You may want to try milling some of the non-AP components to get them finer as well.
I to have this issue right now...i lit two 3lb rockets tonight that took off like a bat out of hell,had a sweet sparkly tail,howled loud as hell The one when the delay kicked in,it accelerated out of sight over the mountain. The other went way up and then arced back down,howling as it was trucking for the earth and then it just exploded with a heck of a bang...thing is neither one had a heading on them,what blew up so loud? they were awesome but had zero popping sound......
The magnalium that does well in strobe rockets is the nice shiny stuff. Dull grey magnalium doesn't work as well. I've milled the dull stuff for a few minutes to 'freshen it up', but that could be dangerous, and shouldn't be done without knowing the risks.
i just picked up 6lbs of it,its brand new i was wondering what was up. i will give that a try for sure,and will get it shined up one way or the other,i have just the idea. thanks man i will post once i get to test it again., im trying a blue strobe thats sugar based this evening when its dry,i made the doc bar white strobe which is fairly simple and hot,so i thought....it would make excellent stump remover the way it is now. it has no issues detonating.lmao
I've never pressed strobe fuel, but have used plenty of MgAl in ground strobes and DEs (and a whole slew of metallic stars). I've never noticed a difference in performance according to shiny/dull status, presumably an oxide layer inhibiting ignition to some extent, but seems dialing in strobe propellant is a different beast that's a little more finicky than my MgAl comps. Have others shared your observation of the MgAl "freshening" approach improving strobe fuel? Seems even if only spinnig a few minutes (I assume with milling media?), you'd be doing as much buffing as you would low-level milling to slightly smaller grains given its brittleness?
The 'freshening' is a touchy subject for some. The general consensus that is spoken quietly among friends seems to be that the dull stuff doesn't make good loud pops. My theory was the oxidation that occurred because of the way the magnalium was processed. I bought a bunch of different mesh ranges of magnalium that is supposed to be 'gourmet', but it is all a dull grey color, somewhat like the old oxidized magnesium I had in jars. It works in stars, no problem. Adding milled magnalium (dangerous!) to strobe propellant speeds up the strobe rate. I bought magnalium from another guy and it was mixed mesh sizes, specifically for strobe rockets. It was (and is) perfectly shiny, with no oxidation. Maybe the dull stuff is dull due to the poor purity of the magnesium and/or the aluminum used to make it, or the impurities make it more prone to oxidation, I don't know. Caleb (Woody) agrees that the shiny magnalium makes the best strobe rockets, and he makes the best strobe rockets I know of. Caleb makes them the Steve Laduke way, with sali booster and a short fat core. The gourmet magnalium that is NOW being made is apparently made with more pure magnesium, and is said to be shiny instead of dull, like it has been all along. I don't know if the water quenching process has been abandoned, but it was my unqualified and uneducated opinion that the water quenching affected the quality of the magnalium. The magnalium from China is shiny, BTW.
I've found strobe rockets to be finicky as well. There's a lot of conflicting information about strobe rockets, because there are two general schools of thought on tooling and propellant that are very different. These differences are often not mentioned in the reporting, when a person has a problem. The people that most commonly report poor popping are using dull magnalium, pottery grade barium sulfate, and/or BP tooling instead of strobe tooling, and sodium benzoate whistle.
I was once given a bunch of old DEs, and they barely popped, and just sort of sputtered. I put it down to the oxidation of the magnalium, which rendered them useless. This is just opinion as well, with nothing to back it up.
sorry i gotta ask because im still playing around with mine. benzoate causes issues? my last two that didnt pop but flew halfway to the moon had benz in them. i dont use sali much,i doesnt agree with me much,lol Not using sali affects how it works?
The first guy to make strobe rockets was a fellow named Doc Barr. His rockets have been described as 'farting rockets', due to the sound of the 'pops'. I made a couple his way from an article in AFN, and they sucked. There is a school of folks that hang on to this 'original' or 'authentic' way of making strobe rockets. These farting rockets are typically made on a long BP-type spindle, and use a tall column of benzoate whistle booster, topped with strobe fuel. I've never heard one of those make loud pops- ever. I mentioned this in another thread, and a proponent of this type of strobe rocket posted a video that I felt proved my point, which is that the pops are mediocre at best. If someone tells you that they get loud pops on BP tooling, just ask to see the video and then judge for yourself if that's the kind of rocket you want to make.
The 'new and improved and used by all the cool kids' way of making strobe rockets is to use a short fat spindle, with a short column of hot salicylate whistle booster, topped by strobe fuel to just over the spindle tip, and finished with whistle. THESE strobe rockets are the ones that make loud pops that sound like a helicopter. Steve Laduke perfected them. Caleb (Woody) and Uncle witty are modern pyros that make excellent strobe rockets with (always) loud pops, and the occasional really loud pop
I'm not saying sodium benzoate whistle is a problem. I'm saying I have not seen it used to make a good strobe rocket. Sodium benzoate whistle requires a longer spindle so more of it can be used to get the rocket high enough, since the propellant is weak. There are VERY zippy variants of benz whistle, but I have not seen them to be used in strobe rockets. My personal theory on why the benz/BP tooling strobe rockets don't make loud pops is because the column of strobe is way up inside the tube. The heat can't get away freely enough, and the separation between the dark and flash phases is less pronounced as a result. The pops are correspondingly weak.
It's important to make strobe rockets in a particular way from a specific set of instructions, if repeatable results are to be obtained. If there is a problem, it's easier for others to help if they know which of the specific methods was used.
Someone please help. 3lb strobe flying great but just not getting that helicopter noise. Followed Neds formula to a t and get ingredients from Skylighter. Using a 4inch spindle 1/2 wide and tapered with 1 degree down to 1/3.
This two-stage rocket is easy to assemble thanks to its quality components and precision laser-cut parts. It was engineered to go together quickly and to maximize the rocket's strength. The see-through payload bay allows you to see your rocket's cargo while it sits on the pad. Great for students and teachers!
The SkyMetra rocket is a great model to choose for your first two-stage flight. It was engineered to be easy to build and prep for launch. It is also great for science fair projects. You'll find that it is the perfect size for launching an altimeter, some toy action figures, or other little gizmos.
The kit is easy to build and features a slotted body tube that allows the tabs on the laser cut fins to mount perfectly straight on the rocket. This makes the rocket fly straight and true, and it is a step up from rockets with molded plastic fins because you build it all yourself! With this kit, modelers will learn the advantages of having lightweight wooden fins. Not only does the model weigh less than a rocket with plastic fins, but the fins can be shaped (airfoiled), which lowers the drag and allows the rocket to achieve spectacular heights. Once this skill is mastered, it can be used on more complex model rockets.
The SkyMetra rocket has the "classic" old-style two-stage configuration. The fins of the bottom stage nest against the back edge of the top stage's fins. They are also in-line with the top fins. This makes it look like a single large fin as the rocket takes off from the launch pad. What's the benefit? It makes this a highly stable rocket, giving you straight up flights. It also reduces the frontal area of the rocket, allowing it to slash its way higher into the air.
Two-stage rockets are a blast to launch. As it screeches off the launch pad, the bottom stage suddenly pops off about 50 feet into the air. Then the top stage fires and begins its ascent. This is often called "pop-and-go" staging. Since it has some velocity when the stage ignites, it really picks up a lot of speed. You better be ready for it! And the extra speed allows the rocket to coast significantly higher into the sky than a normal single-stage rocket. Often, the only indication of the rocket you'll have is the smoke trail coming out of the motor. You might want to have a set of binoculars with you when you launch this rocket.
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