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Old 11-04-2011, 07:47 PM
DGLand DGLand is offline
Junior Rocketeer
Join Date: Feb 2011
Posts: 20
Default High Apogee Low Opening

I kind of raised this qstn previously on another forum but it didn’t get much (any?) discussion there. Plus, I have been thinking some more about the details and I think I have a product idea that would sell……what do you think?

High flying model rockets pose the same recovery problem as high flying highpower rockets. Especially around north Texas, the wind is blowing ALL THE TIME and I am sure we’re not the only ones with this problem. I like to launch ‘em high but I also kinda like to get them back. I don’t like to pack $50 or $100 worth of electronics onto a $15 rocket and still have a pretty good chance of losing the whole thing.

I am looking for a way to accomplish a low-power (inexpensive) version of dual-deploy. I don’t like messing with electronics (cost, complexity, fresh batteries, etc) and I don’t like how you step across the line into a legal quagmire when you have to start storing/using e-matches and loose black powder ejection charges. (And yes, all the ‘substitutes’ still require all the PITA paperwork, licenses, lockers, inspections, and all the other nonsense.) Seems that issue gets all wrapped up over whether the black powder comes prepackaged inside a manufacturer’s motor or if it (the exact same &^$# stuff) comes separately in a can and you use it for something other than a firearm. I am not holding my breath on getting that changed, no matter how cosmically stupid it is.

What if there was a way to do this using a new product with existing paper casing materials for expendable ‘black powder’-style motors? Probably using existing tooling? And existing processes? And existing pyrogens? And (the best part) cheap enough to use once and throw away? (No heartbreak if it drifts out of sight on the breeze!)

(OK, thinking out loud here….) If a manufacturer (like......Estes?) would offer a motor without propellant, including only a delay and ejection charge (don’t know if you would need/want the nozzle), such a ‘HALO’ could be used the same way we currently install an upper stage black powder motor. You could use monster first stage motors (like the new E12), still choose the ejection delay for the main motor as you normally would, and still use that motor-based ejection charge to separate the model rocket into two tethered sections at apogee. The rocket would then use break-up recovery for the initial descent, like many of us already use for high fliers. The ejection charge would also ignite the HALO during separation at apogee.

The HALO would burn and exhaust (feebly?) from the bottom end of the upper portion of the rocket in similar fashion to a discharging second stage motor. The HALO would be selected from a couple of available burn times (maybe 3, 5, or 7 seconds?) and it would make more tracking smoke on the way back down.

When the HALO finished its delay (at a lower altitude) it would ignite a second ejection charge for the main recovery system deployment. You would get significantly reduced drift in the breeze and you would have a much improved chance of recovering your bird. I don’t know about you, but if I had good confidence that I would get my rocket back I would launch more and burn/buy more motors. (Big launch fields are getting harder to find.)

The HALO could probably be packaged into an Estes-style 13 x 45mm “T” paper case. You might not want any ceramic nozzle stamped in the rear, to improve ignition from the first stage motor. You would simply stamp in the delay material (same stuff as currently used) which should fit nicely inside that case if there is no propellant load. The delay materials could even be stamped against the same tooling already used to form the ceramic nozzle---this would provide more exposed surface area for a better chance of ignition. Top it off with an ejection charge (maybe a little extra big load to successfully pressurize a BT50-60-70 rocket?) and retainer cap and you’re done.

If there is an ignition problem with getting delay-pyro material to burn when exposed to an ejection charge, perhaps a small layer of normal propellant could be dropped in first to enhance the reliability of start-up. Without a nozzle to make effective use of the combustion products, the primer propellant would produce negligible thrust, the small charge would flash quickly, and it should be able to transfer the flame to the delay pyrogen (same as in motors now).

If there is a problem with ejection gases venting out the back end and not forward, you could help direct the gas path by stamping in a nozzle-like ring (same ceramic materials?) between the delay and ejection charges. (Possible special production-line tool?)

The 13mm case size would nestle quite nicely against (or into) the front end of an 18mm case and could still be used with 24mm or other 13mm motors. The 13mm size would present only a small weight penalty for the overall rocket design.

Model rockets designed to use this system would look exactly like BT50-60 two-stage birds already do. There would be a set of parts just like a normal MMT to hold the HALO. There would be a stage coupler to hold the rocket sections together just as for two-stage designs. There would be a tether system to attach the two sections, probably using Kevlar cord or something heat resistant, maybe with a length of shock cord in there somewhere. The biggest difference would be that the upper section would not need ‘second stage’ fins….unless you just like lots of fins.

Cost numbers could be funky due to small-batch-economics but at least the manufacturer could use most (or all) of their existing motor production setup and materials----no extra parts or supplies inventory. Cost could/should be in the same ballpark as existing 13mm motors? Packaging could certainly be the same as existing 13mm. Labeling might take a little work but that should not be difficult (not rocket science?) Marketing wouldn’t be a problem because the guys who would want something like this would latch onto it immediately with only a few announcements, and you wouldn’t need to tell the whole world about it because it would just confuse all those first-timer rocketeers (who already cannot figure out the motor codes). No handling of loose black powder, no LEUPS, no permits, no electrical/pyro igniters, everything manufactured and safely/legally packaged just like current low power motors. Nothin’ but net. Since this is not a thrust-producing ‘motor,’ would this even have to be certified by the NAR S&T bunch? (I guess we’d want them to verify that the delay charges burn for the proper time intervals.)

And if you don’t like HALO (too many loyal game players out there?), how about High Apogee Delayed Ejection System?

Do you think this might be a go-er?
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