Travelin' Javelin: a HPR challenge

[ECayemberg]

It always starts with a story…

Some things take time to percolate; this one certainly took its time!

Long before there were Junior Level 1 certifications, there was a boy who poured over issues of High Power Rocketry magazine (HPR) lusting after rocket projects that would have to wait until he hit adulthood. Fortunately that boy has since been able to build and fly most of the projects and more; but a few planted seeds remained ungrown. One of those undeveloped projects originated with an article in the December 1995 issue of HPR. Ken Goldstein, President of the LIARS at the time, wrote a neat article entitled What’s the Frequency Kenneth about a unique project that incorporated VHF tracking, hybrid propulsion, and most notably for this thread, a portable rocket that broke down into sections that fit within a 27” suitcase, allowing for easy transport from the East Coast to the West Coast for LDRS XIV at Black Rock. Not to mention; the project shared the title of one of the greatest songs of the 90's...and Ken's shorts were pretty rad! I was intrigued by the suitcase rocket idea, and tucked it away for another day.



A few years later in 1998, the Vaughn Brothers announced they were releasing upscaled versions of two of their popular 2.6” kits. The Blobbo would grow to 5.5” in diameter while the Javelin would grow to 4” in diameter. I dig the Blobbo (have a 2.6” in the fleet), but really like the classic lines of the Javelin (have a 2.6” Javelin in the fleet too!). The Javelin 4.0 was definitely on the “want list”.





Ruby and Jim from Discount Rocketry are supremely nice rocket people whom we had the pleasure of neighboring with at Airfest 23 in 2017. Being the nostalgic nut that I am, we inevitably discussed the Vaughn Brothers line that they picked up from Jerry and Mike and continue to offer VB kits today. Go buy a Blobbo, darnit! They mentioned a few old fins in a box on the shelf which piqued my interest. Sure enough, there was a complete set of 2.6” Javelin fins and a single 4” Javelin fin. Naturally, the 2.6” Javelin was built shortly thereafter, and the 4” fin tucked away for future use.

The venue change for LDRS 40 was the spark that finally lit this fire. I was interested in the event under OROC’s hosting, however the historical portion of Lucerne seems quite fitting for the 40th anniversary of Tripoli’s annual gathering. Several options exist for convenient access, I’ve never been to Lucerne, and I have a few west coast friends that I’d love to hang out with on their home turf! The early June timeframe works better for my family’s schedule as well. Pencil it in!

Putting it all together: Where am I going with all this banter? I want to construct a rocket that I can pack in my suitcase and fly out to events like LDRS40 at Lucerne. But that’s not all…

If you’ve flown with me before, you may know that I’m not a one-and-done-dude. Attending a launch for me is a busy experience…I’ll be doing a lot of flying, working on the range, and visiting…I might relax a little in the evenings. So, I need this project to be more than just a portable rocket. At LDRS33 at Bong in Wisconsin, I flew the entire alphabet A through N using multiple airframes with the family and had a blast doing so. Let’s narrow the scope for LDRS 40. The challenge is to fly the High Power alphabet (H-M) on a single airframe.

Enter the Travelin’ Javelin.

 

[thzero]

I was gonna say... a bolt together rocket with bolt on fins. Cut the rocket tubing to sections that will fit within the width of the luggage - that looks like from 22" to 32". Then with couplers bolt the sections together.

The fins can be bolted onto the fin can. Either with 3d printed fins, like I've been doing, or going with min-diameter mentality and using Proline epoxy to attach to a external tube that slides over the fin can. In either case you can do 1 fin at a time, or even pairs of fins depending on the suitcase. The second idea requires probably rolling your own tube using the rocket tube as a mandrel, but could be cool

Then you can just unpack, bolt up, and fly.... sorta James Bond style. Mmms... I'm liking this idea myself - maybe not H-M, but certainly the idea.

 

[rfjustin]

Subscribed/watching....

 

[DeeRoc29]

Cool! Looking forward to the flights and hopefully getting the chance to meet you in person, Eric!

 

[dhbarr]

It always starts with a story…

Some things take time to percolate; this one certainly took its time!

Long before there were Junior Level 1 certifications, there was a boy who poured over issues of High Power Rocketry magazine (HPR) lusting after rocket projects that would have to wait until he hit adulthood. Fortunately that boy has since been able to build and fly most of the projects and more; but a few planted seeds remained ungrown. One of those undeveloped projects originated with an article in the December 1995 issue of HPR. Ken Goldstein, President of the LIARS at the time, wrote a neat article entitled What’s the Frequency Kenneth about a unique project that incorporated VHF tracking, hybrid propulsion, and most notably for this thread, a portable rocket that broke down into sections that fit within a 27” suitcase, allowing for easy transport from the East Coast to the West Coast for LDRS XIV at Black Rock. Not to mention; the project shared the title of one of the greatest songs of the 90's...and Ken's shorts were pretty rad! I was intrigued by the suitcase rocket idea, and tucked it away for another day.

View attachment 496735View attachment 496736

A few years later in 1998, the Vaughn Brothers announced they were releasing upscaled versions of two of their popular 2.6” kits. The Blobbo would grow to 5.5” in diameter while the Javelin would grow to 4” in diameter. I dig the Blobbo (have a 2.6” in the fleet), but really like the classic lines of the Javelin (have a 2.6” Javelin in the fleet too!). The Javelin 4.0 was definitely on the “want list”.

View attachment 496737

View attachment 496738

Ruby and Jim from Discount Rocketry are supremely nice rocket people whom we had the pleasure of neighboring with at Airfest 23 in 2017. Being the nostalgic nut that I am, we inevitably discussed the Vaughn Brothers line that they picked up from Jerry and Mike and continue to offer VB kits today. Go buy a Blobbo, darnit! They mentioned a few old fins in a box on the shelf which piqued my interest. Sure enough, there was a complete set of 2.6” Javelin fins and a single 4” Javelin fin. Naturally, the 2.6” Javelin was built shortly thereafter, and the 4” fin tucked away for future use.

The venue change for LDRS 40 was the spark that finally lit this fire. I was interested in the event under OROC’s hosting, however the historical portion of Lucerne seems quite fitting for the 40th anniversary of Tripoli’s annual gathering. Several options exist for convenient access, I’ve never been to Lucerne, and I have a few west coast friends that I’d love to hang out with on their home turf! The early June timeframe works better for my family’s schedule as well. Pencil it in!

Putting it all together: Where am I going with all this banter? I want to construct a rocket that I can pack in my suitcase and fly out to events like LDRS40 at Lucerne. But that’s not all…

If you’ve flown with me before, you may know that I’m not a one-and-done-dude. Attending a launch for me is a busy experience…I’ll be doing a lot of flying, working on the range, and visiting…I might relax a little in the evenings. So, I need this project to be more than just a portable rocket. At LDRS33 at Bong in Wisconsin, I flew the entire alphabet A through N using multiple airframes with the family and had a blast doing so. Let’s narrow the scope for LDRS 40. The challenge is to fly the High Power alphabet (H-M) on a single airframe.

Enter the Travelin’ Javelin.

No f85's?

 

[Tim51]

Fantastic - subscribed! TRF has been missing an @ECayemberg build thread for far too long!
(And somehow I thought from the style of your writing you might be an REM devotee...)

 

[ECayemberg]

Welcome all! I have the day off of work...so more progress today, more photos tomorrow! ...Or maybe today, time and electronic resources dependent.

Cheers!

 

[tjsnakez]

This is great! Takes me back to being a kid reading rocket magazines and dreaming of everything I couldn't have; and most of it would be gone before I ever had a chance. Vaughn Brothers Blobbo... Public Enemy Performer (3x38).... BlackSky Optimal 65... Blackhawk R&D Phoenix... Dynacom Scorpion... every BSD kit... THOY Nighthawk. Looking forward to a classic Eric C build thread!

 

[ECayemberg]

I should note early on that all of the materials used to frame up the Javelin are parts I have on hand. Therefore, the reason certain materials or items are chosen for use is, in many cases, simply because I need to use up some stagnant inventory in the shop! I'll mention the sources and rationale as we go along as appropriate (or as memory allows).

Motor Mount:

The original VB Javelin had a 54mm mount. This rendition will have a 75mm mount to accommodate common L-M motors...the old adage "you can always adapt down, but never adapt up" applies. As one can guess, the mount will be a bit unconventional; no traditional through-the-wall fins on this bird.

The mount is constructed of an eclectic blend of materials. Wildman 4" G-12 coupler 12" long, Performance Rocketry 3" G-12 motor tube 13" long, a pair of 1/2" thick 98-75 centering rings, a pair of 1/2" thick 98-75 coupler centering rings, and a 12" long section of PML phenolic split lengthwise to decrease diameter to fit snugly inside the 4" coupler.

Fun fact: The PML triangles on the inside of PML phenolic airframe must point "up" in order for rockets to fly nominally. The old timers here already knew that!



I'm rusty at this whole build thread thing, so just imagine mixing up 12 grams of West 105/205, adding a bit of colloidal silica, and smearing it all over the scuffed up surfaces. I took one measly photo of the mount during the epoxyification. Here, the motor tube has nested within the 4" coupler, trapping the phenolic tube between the coupler centering rings, and awaiting the upper centering ring to seal the deal.



A bit of epoxy was left over from the marriage of components. Not one to waste perfectly good epoxy, the ID of the booster airframe was buttered with the slightly thickened epoxy. A bit of epoxy was applied to the OD of the coupler for good measure; there's enough of a gap between the coupler OD and the airframe ID that it was used up by the time the assembly was fully inserted...more on that later.



Twist and shout until the aft end of the motor mount assembly is flush with the aft end of the airframe. Set vertical on waxed paper until cured. Ready for some fins and a hacksaw!



I'm still contemplating the finish on the rear end. The voice in my left ear says to go old school and just drill and tap the (1" thick) wood centering rings and use clips/washers for retention while the voice in my right ear is telling me to call the Wildman and get me a flanged Aeropack to clean up the tail of this bird. We'll see which voice screams louder...

 

[ECayemberg]

Materials

Spoiler alert: Carbon. No assembly in this here post...only words and a confusing photo of flat surfaces.

The Vaughn Brothers offerings were traditionally black in color, with a few yellow bands around the circumference and some simple text along the length of the airframe. I dig the simplicity and want to honor the concept. You'll see a similar trim scheme on this rendition.

And then...
A week and a half ago, the old man and I had a blast attending the December QCRS launch. Great company, good times, but less than perfect weather. That darn wind had my favorite Loc Magnum dragging across the plowed dirt fields nearly as fast as I could run after it...and as a BAR (Born Again Runner), I can run fairly fast). The Magnum is a tough bird and sustained no actual damage, but the paint is definitely more scuffed up following the kite flying experience. Also, my few visits to the lake beds (Black Rock, Smoke Creek, Jean) have taught me that there's wind out west as well...and that tends to drag rockets across the playas with ease. So....I didn't really want to paint the Javelin black.

But wait, there's more...
Who remembers Rocketry Online? That's right, before The Rocketry Forum; even before Rocketry Planet, there was Rocketry Online! It was a great news feed, auction site, and forum, essentially the product of brainchild Darrel Mobley. While I rarely used the auction portion of the site, occasionally something *really cool* would pop up and prompt a purchase. I happened to buy a pre-production version of Performance Rocketry Competitor 4 in 2004, which became my L3 rocket. Side question: was the Competitor 4 Curtis' first kit? I *think* so! Anyway, I also purchased a 4' long length of 4" filament wound carbon fiber airframe from Holsopple, PA from an undisclosed source...curious if this was also a Curtis product, but this was long before he offered filament wound products...hmmm. Anyway, while the carbon tube was really "pretty", it had a few flaws, it was too short to be used with acceptable minimum diameter motors (48"+), and it was slightly oversized...wall thickness was a nominal ~.062" but the ID and OD are both a few thousandths greater than common rocketry sized components. For these reasons, the tube sat idle for the last ~20 years! But it is black in color, fairly light, available for use (long overdue!), and fits the profile for the needs of this project. Put me in, coach! Similarly, the payload tube is a shortened version of an also-too-short 3' section of Wildman filament wound carbon that I *think* I got with a 98mm Blackhawk Black Saturday purchase...the rest of that airframe is being used for a minimum diameter N4000 flight scheduled for Airfest 2022.

Is carbon fiber necessary for this project? No! Is it an underutilization of materials? Absolutely! Is it black in color, fairly lightweight, and on hand? Most definitely. So the Travelin Javelin's outer shell will be all carbon fiber...get over it.

thzero mentioned removeable fins earlier. Absolutely correct! These are also carbon...also cut from material I had on hand for years. Originally purchased as base material for some fast/high flyers for Black Rock and/or Argonia, the autoclave pressed multi-directional uni-carbon plates came from ACP with an annoying 90 degree bend at the base of the plates. I purchased 5 or 6 of the plates at the time, and had 3 full plates and a few partials left over. The annoying bend is an essential part of the removeable fins. More on the fins later, but three primary fins were cut from the flanged plate; a fourth was cut as a spare. Rough cut fins below. The spare in the foreground was squeezed out of a partial plate; has some flaws and will only be used if one of the primaries sustains irreparable damages.



More to come as progress dictates. Thanks for following along!

 

[ECayemberg]

Chop Chop!

I've been guilted into posting an update. It wasn't that I forgot about this thread, or the Javelin at all, it's just that I saw a squirrel or two! The squirrels names were: NCR Cluster Duck, BMS 3" School Rocket, Loc EZI-65, 4" Skyraider, 4" Wildman Punisher-turned-Darkstar, and a trio of Loc Goblins needing attention. Most importantly, one of the Goblins is my elder son's Junior Level 1 rocket, so that was a worthy distraction!



Now that the squirrels have left the bench, back to the Travelin' Javelin!

First up, let's cut the perfectly good one piece booster airframe into two sections: 26" lower and 22" upper. Both sections will be 26" long once we add the coupler to the upper section. A ring of tape was made around the circumference; using a wrap of B size paper as a guide. Prior to cutting the sections apart, an alignment mark is made over the joint using a light touch of a Dremel and cutoff wheel. I prefer to use a trusty hacksaw to cut tubes...



Once the tube was cut and the ends trued up with sandpaper, the next logical step is to re-join them! Rocketry is logical...said nobody ever! Sharpie marker on the coupler aligns with grind mark on the airframe. Tape holds things in place until the drilling commences.



A drill guide was created: six #6-32 screws around the circumference to fasten each section. Drill, tap, screw, repeat. This was done to both upper and lower sections of the booster airframe. Tip below at the end of the post.



In order to properly screw, a booty call to McMaster Carr was in order. I love that place. Just about any material, hardware, or tool that one would ever need at affordable prices and with solid quality. Order one day, "standard" delivery the next (at least to Manitowoc, WI). Along with a few forged eyebolts, ball drivers, and stir sticks, the order contained a bunch of black oxide machine screws for this project.



The screws chosen to fasten the sections together are #6-32 x 3/16" long flat head screws with an undercut head. The airframe was countersunk to allow the heads to nest in the airframe; though the countersinks were kept shallow enough that the heads sit "proud" of the airframe's OD just a tad. The little extra drag is welcome for this non-optimized rocket, and I didn't want to lose too much material with a deep countersink. TIP: once the holes are drilled and tapped, remove the coupler and countersink the airframe only. With an undercut head screw and a relatively thin surface to tap into, you don't disturb the full ~.062" of thread engagement on the coupler...helps reduce the risk of stripping out the threads significantly.



That's all for now. Next up, fins!

 

[StreuB1]

 

[boomtube-mk2]

I was gonna say... a bolt together rocket with bolt on fins. Cut the rocket tubing to sections that will fit within the width of the luggage - that looks like from 22" to 32". Then with couplers bolt the sections together.

I wonder how TSA would react when they ran that through the X-Ray machine? My guess would be, not well.

 

[StreuB1]

I wonder how TSA would react when they ran that through the X-Ray machine? My guess would be, not well.

I design Xray machines for a living. I might bring a rocket in tomorrow to see how well it shows up. I would say that the majority of the rocket will be invisible other than the outer perimeters and areas of the fins (depending on orientation) that satisfy the materials critical angle. Which for xrays is extremely low, especially in plastics. So, there will be diffraction as the beam approaches the tangent point of the tube and areas of the fins that present an extremely acute angle (<1°). So, we should get shadows in those areas. How those shadows resolve to actual images is the question!

One thing to note. Airports use dual energy xray systems which is highly specialized and designed to see things that are generally invisible to xray. The images I will take tomorrow will be single source (single energy).

 

[boomtube-mk2]

I remember when they X-Rayed my carryon bag, this was years before 9/11.
The bag held, among other things, a small handheld hairdryer and a big bottle of muti-vitamins.
The image on the screen showed the inner wiring of the dryer and the vitamin bottle was just a dark irregular blob.
Taken together they looked remarkably like a bomb.

 

[StreuB1]

I remember when they X-Rayed my carryon bag, this was years before 9/11.
The bag held, among other things, a small handheld hairdryer and a big bottle of muti-vitamins.
The image on the screen showed the inner wiring of the dryer and the vitamin bottle was just a dark irregular blob.
Taken together they looked remarkably like a bomb.

The vitamins were likely iron fortified. Iron is an excellent xray attenuator.

 

[OZRoc]

Anyone using bolts / screws to hold together sections of airframe / coupler I highly recommend using what I call nutserts but also known as rivnuts.


I even use these on cardboard material.
Much more positive retention and don't have to worry about stripping threads created in the wall material or messing about gluing nuts in.
Cheers

 

[StreuB1]

Anyone using bolts / screws to hold together sections of airframe / coupler I highly recommend using what I call nutserts but also known as rivnuts.
View attachment 498456

I even use these on cardboard material.
Much more positive retention and don't have to worry about stripping threads created in the wall material.
Cheers

I use them all the time at work in my designs. Though we use stainless, closed end, low profile countersunk heads. Fits beautifully to airframe.

 

[g.pitts]

Anyone using bolts / screws to hold together sections of airframe / coupler I highly recommend using what I call nutserts but also known as rivnuts.
View attachment 498456

I even use these on cardboard material.
Much more positive retention and don't have to worry about stripping threads created in the wall material or messing about gluing nuts in.
Cheers

I use PEM nuts with a little epoxy on them "just in case" since we're installing something intended for a flat surface onto a curved surface.

Can you show a photo of the outside of the coupler? I'm guessing you countersink the rivnuts so there's no interference with the body tube(s) that I assume slide over the coupler?

 

[ECayemberg]

Thanks Oz, g., and Streu! I'm pretty excited that this thread now has the words nutserts and rivnuts in it!

Though I haven't used rivnuts, I have PEM nuts installed on several rockets. I'm going to stick to my guns on this one and settle on the tapped 'glass for joining the sections. Famous last words: I've yet to strip drilled/tapped holes in G-10, G-12, or equivalent in rocketry. I've broken solid strand wire, had capacitors and screw terminals bend/break off of electronics boards, straightened eyebolts, elongated swivels, ...but never had a screw strip out of a 'glass surface. If they do, I'll just drill the hole on the coupler side bigger and install one of those fancy metallic nutty things!

Plus, remember we've got this 4" pig on a diet and it needs to go through X-ray prior to boarding the plane...so I'm trying to minimize metallic components when possible to reduce weight and funny looking x-ray imagery!

Fin installation coming soon. Two out of the three fins are "on", but I'm waiting until all three are installed to make the next progress update. Going back to work following a few days off over the Christmas-New Years week is really cramping my rocket building style! Thanks for your patience and presence!

 

[DeeRoc29]

How's this project coming along?

 

[ECayemberg]

How's this project coming along?

Derek! Just saw this now. Oh man, it was put on the side burner. I'm actually farther along than the thread indicates, but this project was trumped for a few reasons:

• My LDRS trip was traded for a Texas trip a week earlier. More on that somewhere else sometime....
• A good friend named Tim reminded me that he has a child named "Midwest Power" that turns 20 this year. There might be a special project to celebrate that milestone. It's possible I'm working on that project currently.
• Life happened.
• I needed to make some *large* research motors in a fairly short timeframe. That trumped everything else free-time related.
• Life happened.
• Baseball season started for the kids!

Basically, it's still going to happen, but it might be a Black Rock project for fall '22, or maybe a Lucerne (ROCStock?) project for '23. In due time, we shall resurrect this old thread. Thanks for checking in; and I'm sorry I missed you out west!!!