Best Strobe Rocket Design for 1 Ton Arbor Press?

[LiamPyro]

I’ve been really enjoying rockets and rocket-type devices lately and am considering trying my hand at making the legendary strobe rocket. I press all my rockets on a modified 1 ton arbor press with a homemade PtoF gauge. I’ve got the parts lying around for a blast shield. I know strobe/whistle fuels typically require high pressures, so it seems like my limit would be 8 oz and probably more like 4 oz in order to achieve the recommended PSI with this press. I have a few questions before I commit to a tool: 

1. What factors should I consider when choosing between Woody’s standard strobe tool and the extreme version? I understand that longer spindle = more surface area, so it seems like getting the extreme tool would be my best bet to get the most out of smaller rocket diameters.

2. How about tube length? I’ve often seen strobes pressed on shorter tubes, presumably using a short sali/strobe spindle - what’s the deal with this? I’m assuming Woody’s standard and extreme strobe tools are meant to be used with full length tubes? I’m inclined to build longer /skinnier strobe rockets given my pressure limitations…

3. Can waxing the tubes (I already do this) allow for lower pressing forces on strobe/whistle or do I still need to target the commonly cited 7500 PSI? If I can get away with lower pressures, I might opt for the 8 oz tool (max 5700 PSI on the comp with my press /gauge range, not accounting for spindle area). Should I just stick with 4 oz, where I can press 9000 PSI on the comp?

 

[cmjlab]

There are people far more experienced than me, but based on some quick conversions....

If you get the full 1 ton (2k lbs) from your press, I'd bet you would be good for 5/8" tooling.  Since you need 2300 lbs to achieve 7500 on the comp for 5/8 tooling, you'd only be a few hundred pounds short with a 1 ton press.

(**edit - I just re-read your bullet #3 and see that you must not be getting the full 1 ton with your press, so I guess Idk based on that.  My bad.**)

Good luck, I'm interested to see what info people give you as well.  I know I like using the 5" tubes for 1" whistle and strobe rockets, because it is quicker to make and takes less composition - but I don't think the shorter tubes would work well with potassium benzoate whistle as the booster.  I could be wrong, I've never tried it. 

Edited November 10 by cmjlab

[LiamPyro]

Thanks for the response! The reason I specified 5700 PSI is because my PtoF is built with a 1.5” hydraulic ram and 1000 psi gauge, so 1000 psi on the gauge gives 5760 PSI on 5/8” diameter. I may upgrade the gauge to a 2000 PSI gauge to allow for higher forces. This also raises the question - can the HF 1 ton press be used above its rated max without damage? 

What tooling are you using with the 5” tubes? How is the strobe performance? Good popping?

Edited November 10 by LiamPyro

[cmjlab]

I don't know if you can go above the rated weight without breaking anything, or even up to the rated weight without breaking teeth on the ram, but 1 ton = 2000 lbs so I still think you could get close to 7000 lbs of force on the comp with a slightly longer arm on the press. But you are right, you'd want to buy a new pressure Guage for $10-15.00 to keep an eye on the weight. Caleb does make nice tools and it would be a shame to wreck it by pushing it beyond its limit.  

My math was never great though.... 🙂

[Arthur]

Whistle doesn't play nicely if you get it wrong. Buy a small tool that fit's your press's limits. Make small whistles til you are certain that you have the method perfect. Only then look at stretching the press's limits.

Make absolutely certain that you have all the intended blast shields in place for pressing and enough space for a CATO of an energetic mix for when you do tests. Maybe you can do initial tests pointing down a hole in the ground so that a cato doesn't send lumps of shrapnel

[LiamPyro]

Good advice. I already have a longer handle on the press and can easily achieve high pressing forces, but as mentioned above, snapping teeth on the ram or gear would not be so great. I’ll be sure to do testing safely, with the assumption of CATOs. I’m still trying to evaluate the pros and cons of the standard vs extreme strobe/whistle tool, and whether or not I should use full length tubes. It’s unclear to me what effect the relative dimensions of the rocket have on performance, though I did read something about how the “original” strobe rockets used long skinny BP-type spindles while the modern “better” version uses a short fat spindle. In my mind, a longer spindle and longer fuel grain would allow for greater performance and overall effect when comparing rockets of the same diameter, but I don’t really know. If the whistle fuel is too hot for a long core, can’t you just use less and therefore have more room for strobe fuel on the spindle? Maybe this is wrong and strobe rockets just aren’t intuitive in this way?

[DavidF]

Waxing the tube helps overcome flaws in motor construction so they don't cause CATOs, but it's not magic. The original strobe rockets were made on a long spindle, and they were not great. Then Steve Laduke perfected them. Then along came Woody (Caleb). He's got a natural knack for strobe rockets. Both Woody and Laduke use shortish spindles and short tubes. 

Florida Pyro does a lot of videos on small whistle and strobe rockets on YouTube. His videos should be quite helpful to you. 

My personal opinion as a mediocre strobe rocket maker is that there are a lot of different things at play at once that have to be perfectly balanced for the best strobe effect. The guys making the boomer strobe rockets in LA neighborhoods are all using short, fat rockets. 

One unsubstantiated theory that I have is that there must be an appropriate balance between the light and dark reactions, which occurs when heat is allowed to get away easily (short, large core). A long tube or skinny core seems to mute the effect- one guy's opinion.

If you can get Caleb on the phone, he can best advise you on what tooling to get. 

[FrankRizzo]

I've never got a satisfactory pop from small strobe rockets. IMO, you need to go up to 7/8" bore motors (or larger) to make one that pops loud enough to make a satisfactory rocket. Unfortunately, your 1 ton press isn't likely to give good results with that size motor.

You could try dampening with a solvent like acetone to help lower the consolidation pressure necessary, but the motors will take a long time for the solvent to leave (even with heat).

[cmjlab]

I mis-spoke above, I am not making 1" rockets.  I meant to say 5" long tubes, and "1# rockets" or "3/4" rockets".  I'm using Caleb's 3/4" strobe tooling.  I've also made them on Caleb's 3/4" hybrid universal tooling, and on Ben Smith strobe tooling, both of which require full size tubes due to spindle length.  

Also, as i initially stated, I am no expert strobe maker (cylinder shells are my true love and what i am proficient at) - I'm a mediocre strobe rocket maker at best, as described by David lol, especially if comparing to Caleb and LaDuke.  I've always struggled to get the super loud pops and never cared to share my results because of that.  

I can only speak to pressing with an Arbor Press (though i use a 3 ton arbor press off Amazon) and tube sizes I like using, and why. I wish I could tell you the secrets to making excellent strobes - but I think David F's and Frank Rizzos advice above is more helpful towards that end.

[LiamPyro]

Florida Pyro’s strobes are pretty insane, and he has clearly done a lot of experimentation to get them there. Even his 4 oz are impressive. I might consider shelving this project until I eventually invest in a larger press, or alternatively, start small with what I have now to perfect the method while using smaller amounts of chemicals (that was the original plan). Woody’s stuff has been good so far, the 8 oz super BP tool I got makes some insane rockets. Mine lift 170g headers without any special tuning of the fuel… I’m sure they could lift more. I may seek his advice on strobe tooling. 

 

[LiamPyro]

Update: I just spoke with Caleb and got some info around the differences between tooling, for strobe specifically. From what I heard, there’s no real benefit to having a core depth beyond 2-2.5” extending into the strobe fuel itself. The effect is produced from the fuel burning radially from the core to the tube wall (makes sense). This determines duration. Longer spindles are intended to make room for more whistle for stronger lift, that’s it. There is apparently a trade-off between thinner and thicker spindles, with thinner allowing more fuel between the core and the tube wall but with the risk of the core clogging up from “foaming up” of smoldering debris. Thicker spindles reduce clogging but at the expense of strobe duration. For this reason, Caleb warned that strobes are very finicky below 3/4” ID, and perform optimally around 2 lb or larger, where there is plenty of room for lots of fuel around the spindle but also enough clearance for debris. Caleb, if you ever read this, I hope I relayed everything accurately. Thanks for the advice.

[cmjlab]

Thanks for sharing.  It's a logical explanation, and his strobe rockets are second to none!

[LiamPyro]

14 hours ago, cmjlab said:

Thanks for sharing.  It's a logical explanation, and his strobe rockets are second to none!

No problem, thanks for engaging with this thread. I’ve also reached out to Florida Pyro, another esteemed strobe maker, to see what his thoughts are regarding core geometry and also loading pressure. I’ll continue to share any noteworthy information here. Hoping to begin my own experimentation when I’m back home to the lab this winter, even if it’s with a smaller “suboptimal” diameter. Florida Pyro has roaring 4 oz strobes so it certainly can be done…