Discount Rocketry US "Bullet" Modified Night Launch (LED illuminted) Build-Log

[Paul Howard]

Here's some out of order pictures but you'll get the idea. I really like the kits and dealing with the people at Discount Rocketry US and their USA made rockets. I got one of the last kits of the "Bullet" and I'm modifying it with an added clear payload section with LED's for night launches. If you look at the"BLAST SIDE" of the ejection baffle, you'll notice a circular piece of aluminum can applied with epoxy (which covers the wood of the "blast side" as well) - this is an experiment to add some durability to that side of the ejection baffle.

 

[Paul Howard]

More pictures. The forward end of the motor mount has an extra "flat end" so that debris between the motor mount and ejection baffle can be more easily removed. Vent holes were added to the trailing end of the motor mount for pressure equalization during flight. The fins have had hardwood Sitka Spruce leading and trailing edges added, sanded to asymmetrical "lifting" airfoils with nice sharp trailing edges to induce very slight spin for straighter flights, then covered with Sig brand Tissue - it has a "Strong Axis" which I have running perpendicular to the grain folded over the leading edge, that way it's doing it's most to stop splits along the grain of the wood.

 

[Paul Howard]

Here's more out of order pictures: The Discount Rockety US picture that came with the kit, a batch of estes igniters I'm treating with nitrocellulose fingernail polish, launch of an old beat-up Custom Rocketry "Venture", Estes "Fatboy" that had an A10-3T "Roman Candle CATO" (yes, I logged that on www.motorcato.org), My insertion of the eyelet-screw into a dowel placed into the balsa payload block at a 45 deg angle for more clearance of clips-n-stuff in the small limited space between the top of the ejection baffle and the bottom of the payload section, and Putting Paper Inside the Plastic Clear Payload Tube Before Dripping Cyanoacrylate Into the Balsa to AVOID CA FUMES SETTLING ON AND FOGGING THE CLEAR PLASTIC TUBE LIKE LAST TIME I DID THIS -learn from my mistake. And lastly, what my "Modified Bullet" is looking like so far. I'm using CA then Shellac on the Nose Cone (I like natural wood finish) and fins (I like showing off the hardwood leading and trailing edges under the tissue paper, and the look of the tissue paper is appealing to me).

 

[Paul Howard]

Getting closer but not done yet. Fins and Balsa nose cone finished with 2 smearings of Cyanoacrylate and several coats of Shellac to show off the character of the wood. Body done with Testers Yellow spray paint. More to come.

 

[Hobie1dog]

Thanks for all the pictures

 

[Paul Howard]

Here's the "light unit" construction and installation. I got several of these cool LED light strings from eRockets.biz (the Ohio fun kids who run Semroc). The battery pack used 2 common CR-2032 batteries. I made the body tube cutting jig awhile ago from wood sitting around. I used a BT-50 tube for the housing and installed a used 24mm D12-3 casing under the cut-line while cutting for a better cut. The shiny silver is self-adhesive material sold at most hobby shops. More to come!

 

[Paul Howard]

Here's more of the same...... I used an awl-punch to put vent holes in the clear plastic payload tube for general pressure-problem-prevention and possible altimeter use at some point. Note venting notches in "light unit" top and bottom centering rings also.

 

[Paul Howard]

Taa-Daaa!!! More to come with the Recovery-system-stuff.

 

[Paul Howard]

Thanks for all the pictures

Glad you like it!

 

[Paul Howard]

Now for the pre-flight "Swing-on-a-string" test which passed with flying colors with the payload section empty and an Estes C5-3 installed. The nose cone used here is pretty dense balsa, thus, I really wanted to highlight the wood with the finish. It looks sooooo cool, I kinda want to use a different nose cone so that no mishaps ruin it's nice appearance.

 

[Paul Howard]

Recovery system afterthoughts.....The parachute is an 18" woven fabric chute from Apogee Components that I put the Vent-hole in, sewed 2 seams around the hole and modified the anchor points of the shrouds/lines. I used a heavier 100lb test Kevlar line anchored to the modified ejection baffle (also from Apogee Components) and put the smaller kit-supplied Kevlar away for something smaller. I used the supplied 1/4" shock cord from the kit. I put 2 layers of different diameter heat-shrink tubing over the Kevlar where it contacts the body tube to hopefully reduce abrasion to both the body tube and the Kevlar cord. I've recently started using "parachute blankets" and this one is from LOC Precision but cut down from a much larger one that I ordered and didn't realize how thick the Nomex fabric would be. It actually turned out to be a good thing since now I have extra material to custom-cut "parachute blankets" in whatever size I want for LPR's such as this 4" square blanket. You can see the top of the ejection tube from the top end, and you can see the aluminum pop-can "blast shield" on the bottom of the ejection baffle through the engine mount tube.

 

[mh9162013]

Cool build!

Did your modifications to the baffle include shortening/compressing it?

 

[Paul Howard]

Ye

Cool build!

Did your modifications to the baffle include shortening/compressing it?

Yes, It's reduced to about 1/3rd the "normal" length of the Red tubing-coupler (So now I have about 2/3rds of a coupler to use for something else later). I only did that since the body tube of this rocket is rather short and I wanted to be sure I would have enough room for the parachute, kevlar, elastic cord, fishing swivels, the heavier bulky parachute cord lines on woven fabric chute, and clips and split rings, and either a parachute bucket or parachute blanket - as seen in the last photo's.

My main goal is Fire Prevention and it's an experiment to see if a short ejection baffle works or not, and to see how necessary the "One Caliber of body tube diameter from the engine rule" is.

It's probably about 3/4" to 1" above the engine mount since that would still be "One Caliber" if this were a BT-20 or BT-50 size tube but in this case, it's a BT-60 size tube. I also have the aluminum "blast shield" epoxied onto the "blast side" directly in the center of the harshest part of the ejection blast. By being closer, the ejection charge path has to divert at a steeper angle to make it into the baffle to begin with so that "may" help, maybe not. Total "flame length" of the ejection I'm sure come into play as well, so we'll see. I still waiting to have a calm evening to go launch.

Glad you like it!

 

[mh9162013]

My main goal is Fire Prevention and it's an experiment to see if a short ejection baffle works or not, and to see how necessary the "One Caliber of body tube diameter from the engine rule" is.

Please report back your results! I'm thinking about installing a baffle in my next build, but hate how much space they take up due to their length and how they eat up any usable space on the rocket due to the distance they "need" to be from the engine.

My prediction is that being closer to the engine will primarily affect lifepsan of the baffle, although with special reinforcements, it'll be fine.

As for being shorter length, it might affect its ability to eject the nose cone and chute, although I would assume your modification would still work just fine. My gut says the length of the Apogee and many other baffles is a holdover from earlier designs that were fairly long. And when designing a new one, they just kept the length of the earlier designs because "that's how dad did it, and that's how American does it...and it's worked out pretty well so far."

 

[Paul Howard]

Yes to most of the above^, thinking of the close proximity, hopefully the aluminum will do the job for the short blast. Also, the length may be partly for convenience of using off-the-shelf couplers. As far as ability of the ejection charge to eject the nose/payload section, I do the "blow on the motor mount test" for that and the payload plug comes of really easy, almost too easy like maybe I should carefully shim with layers of shellac since copy/typing paper is too thick for that gap -i.e.. I don't anticipate a problem there at this point. I'm just waiting for the right launch conditions and wanting to see this thing fly!

 

[Paul Howard]

Memorial Day Test flight(s): I first used a B6-2 and it flew great, not real high but nicely and with the LED light system removed. Next I put the C5-3 "Super C" in with the LED light system in and it's a really nice motor for this rocket! I have video footage but the file seems to be too large to load onto this website.

The one sorta humorous part is the aluminum pop can shield on the " blast side" of the ejection baffle came loose and now rattles around inside. In retropect I probably should have cleaned it with denatured alcohol, scoured a texture to it, then clean again with denatured alcohol, then epoxied it with JB Weld. So, that's what I'll do next time.

The Shortened Ejection Baffle worked GREAT! I used No recovery wadding but used an LOC Nomex Parachute Blanket which worked GREAT and it showed very, very little soot from the ejection charge.

Overall, I'm VERY PLEASED with this rocket, it flies really nice, straight flight (s-l-i-g-h-t induced spin in the fins with good airfoils), it didn't seem to "windcock" into the breeze in any excessive amount which I was anticipating it likely would have but didn't.

 

[mh9162013]

Thanks for reporting back.

You results confirmed that when I install a baffle, I'll make it shorter than recommended. I also plan on using the baffle with reusable wadding.

 

[Paul Howard]

Thanks for reporting back.

You results confirmed that when I install a baffle, I'll make it shorter than recommended. I also plan on using the baffle with reusable wadding.

Adding the re-usable wadding is probably still a good idea. In my case, the LOC Precision company Nomex Parachute Blanket(attached to the Kevlar portion of my shock cord) worked great and the combination of the ejection baffle and blanket seems like a winner.

 

[Paul Howard]

If you want to see this Gem launch on video, it's on Facebook on the "Scratch Built Rockets and Repairs" page and "Rockets USA" page. I tried to load the video here but the file size is too large.

 

[Paul Howard]

Night time launch Sun 10-30-2022 with the Bullet, Finally!!! Great calm air, dry with cloud cover on a nice not-cold evening with no condensation all over everything. Fun!!! Estes C5-3 motor, LED's from erockets.biz, ejection baffle plus nomex parachute blanket worked really well (no recovery wadding). Sorry for the shaky video, it's hard to juggle the camera and set off my dual dead-man switches on my launch contoller.

 

[mh9162013]

Great pics and video! Love the look of the orange flame and blue light.

it's hard to juggle the camera and set off my dual dead-man switches on my launch contoller.

Why do you have those? Just b/c?

After reviewing many "safety" features of home-made launch controllers, I've come to realize many of them exist for novelty purposes, not practical or safety considerations.

 

[Paul Howard]

Great pics and video! Love the look of the orange flame and blue light.


Why do you have those? Just b/c?

After reviewing many "safety" features of home-made launch controllers, I've come to realize many of them exist for novelty purposes, not practical or safety considerations.

I have the required removable key plus 2 dead-man switches instead of only 1 for more safety to avoid unintentional firing. It's actually more awkward than just having 2 dead-man switches and hard to explain without a picture - I'm going to rebuild it better hopefully soon.