Snap Crackle Pop

[edwinshap1]

Well here it is everyone, after 3 months of playing around, i finally have gotten everything together (minus the nosecone, the trailer was out of von karman 38mm )

ill post everything up in a little bit, but i just wanted to get it out there that i'm actually going to do a build thread

oh, and its 38mm min diameter rocket, and its gonna go fast, and i can paint it however, so i need name/color ideas too

original thread that i really get sad about when i look back :P http://www.rocketryforum.com/showthread.php?t=16790

[UPscaler]

Mach-ing bird

Whatever you do, get decals from Mark at stickershock23.com


Braden

[edwinshap1]

I've built the blue tube electronics bay. i'm so glad i didn't make my own, this was so simple (im following KISS )

but i'm not entirely sure what the best type of knot to tie a shock cord to an eye bolt is. anyone know?

picture 1: bulkheads/sled, and tube
picture 2: everythings attached and ready to go

[edwinshap1]

If you are using Blue tube, then you aren't going for abseloute optimum altitude. I would only really use the Von Karmen shape when going for a record, so I would recomend using a nose like the urethane nose cone from Pml https://blastzone.com/pml/ While it might not be the most efficient nose shape it is more available. (If you want max altitude use two layers of Carbon Fiber tubes, a Von Karmen nose, and the Raven 38mm av-bay). From the flight line you wouldn't see the difference, and I would bet that the slimeline retainer causes more drag than the cone would. (I am basing all of these assumptions off of your previous thread) Just my

ah, no slimeline anymore, and i'm not dropping like 100 bucks on tubing lol.

also i was checking out the 38mm solid cast nosecone at the ROC launch yesterday, and it was heavy as hell. and von karman will be much better for when i go for L2.

[lkal32]

Nuetron,
Please take no offense to this, but you are scolding him to not use a VK nosecone because its not high enough performance yet you tell him to use carbon fiber when the blue tube would more than suffice? Let him build it how he likes.

[Chrisn]

Why does it matter if you use a VK nose cone for a non record attempt flight? Have you also heard of optimum mass?

[Neutron95]

You're right- my comments weren't quite appropriate, but they seemed right at the time. I have actually contemplated using blue tube, and I am actually working on a similar 54mm project.

[lkal32]

I have some 6" blue tube for my L3 project. It will be the first time Ive used it and I am quite anxious. But back to the main topic...

Edwinshap,
I mostly use quicklinks to join my shockcords and attachment points, however, in other cases I usually just tie an overhand loop and join it with a girth hitch knot. Simple and quick.

[Buckaroo]

I'm pretty sure I saw you in Jack's trailer carrying that blue tube around . I use a figure eight follow through knot to attach my recovery harnesses. Its a knot I learned for rock climbing. It wont cut into itself under lead and it can be untied fairly easily after its been loaded. There are better pics for learning it online but this is how I do it.

[edwinshap1]

I mostly use quicklinks to join my shockcords and attachment points, however, in other cases I usually just tie an overhand loop and join it with a girth hitch knot. Simple and quick.

quiklinks are a bit of an issue mainly cuz the bulkhead nearest the motor will be inside a coupler about 7.5 inches down sealed off. The knots on the E bay will be easy to access, and the connection between the NC and kevlar is still being worked out, might put a bulkhead at the fore end of the main chute bay.

Updates: Cut the blue tube to correct sizes for the sections im making. thinking of buying something to cut me bulkheads correctly since my technique does leave fairly big gaps between the bulkhead and tube, and i'm having trouble with this friggin E bay. there isn't enough space GRR!!!

I've gutted most of the sled that it comes with, and the battery is fitting in a different way. wiring this is going to be a major PITA, but it'll work nice when it's done

Pics:
1) Using a drill press to make the vent holes (4 of em)
2) cutting the BT with saw...this tube is ridiculously hard
3) failed attempt at making a bulkhead
4) E bay set up as of now...i need to figure out how to keep components from being compressed in there...stand offs i think might not work, hmm
5) i feel like i should just get rid of everything but the wood on the rails since the rails are guided by all thread, but yeah XD

please gimme tips on how to best form the E-bay

[edwinshap1]

wow, this is one strong knot, thanks

[blackjack2564]

You may have cut up the sled too much to do this, but you can always start another. Here is how I do all my 38mm bays

Mount the electronics & battery on one side not through the middle.

Forget about the mounting tubes.....don't need it.

Slide the sled in with the tie rods on top & bottom. Not with sled mounted to them. You will gain tons more room. The sled sits off center so you gain more height for battery to fit. Just cut sled narrow enough for this.

This one has a tube centered on it because I can use it on ALL my larger AV-bays this way. It will slide over 1/4in allthread used for tie rods on larger bays.

Also note I tie shock cord directly to eyebolts. Don't use quick links because you have to tie it to them, so why bother, save another bit of weight!

Battery is taped on the one way because a wire tie won't fit in the tube, only use wire tie the other direction where space not an issue.
Notch on side of sled for battery wires to fit.

I put straws over tie rods so touching any electronic parts is not an issue. [insulators]

If that's a 1/4 eyebolt, ditch it for a 3/16 and gain some more room. File off any remaining threads coming through the bolt if they interfere with getting a longer sled in. See how the eyebolt is filed flush with nut.

Cut sled so it fits perfect end to end then it can't move when BP's are installed. It should also be cut so it's low enough that the nuts from eyebolt clear the sled . That will keep it from moving up and down.

[edwinshap1]

ohh, the blue tube e-bay's allthreads are closer together, and the battery barely bearly can fit in lol

i do have some 1/16" ply, i can make another shot at it

[blackjack2564]

ohh, the blue tube e-bay's allthreads are closer together, and the battery barely bearly can fit in lol

)

Move them & fill the old holes.

All the more reason to not buy pre-fabed kits and build them yourself the way you wish.

If it is a kit why doesn't your stuff fit?

[edwinshap1]

Move them & fill the old holes.

All the more reason to not buy pre-fabed kits and build them yourself the way you wish.

If it is a kit why doesn't your stuff fit?

very good points lol. well on the apogee website (didn't buy from there, but it's a great resource for some stuff), tim shows that the 38mm e bay he got has an aluminum sled...and the rails are much further out. well i'll get back on it this weekend since school is overloading me as of tonight XD

i think i'll keep the holes since i do need to run wires to the charges anyway, or at least 1 on each end :O

[edwinshap1]

ill upload pics when i have time.

rebuilt the e-bay:
used 1/16" ply, drilled new thread holes in the bulkheads...

unfortunately putting them further out made them run into the inside ring that keeps the bulkheads from sliding around, so i had to cut notches in the side with the interior nuts.

now i have enough room for everything, just gotta figure out how to mount it all

TY CRAZY JIM!!!

[gagreen]

late chime in, but k and s has pretty slick 38mm ebays.

[edwinshap1]

late chime in, but k and s has pretty slick 38mm ebays.

i've checked that out. if i got something that wasn't necessairly compatable with blue tube, i'd get the shotgun recovery system from GLR, but i'd need to buy the Mariah for that, and i really wanted to scratch build my cert.

[edwinshap1]

I've decided to name my rocket "low&slow"

updates: i've seated the electronics, i still drilled away most of the board so i now have ample room above and beneath for when i shove the wires in.

All i need now is the little clip thingie for my 9v battery (for some reason every 9volt item in my house is gone, so i'll have to buy one), and the bay will be ready to fly.

next on the list...FINS!!!

I can set the fins perfectly, but i'm not entirely sure how to fiberglass them. Like how do i tip to tip when the rocket body that the fins will be mounted to will be so small, or i guess how do i keep the fiberglass on the body of the rocket when i can't really be holding it there while it sets?

[edwinshap1]

alright, E BAY COMPLETE!!!

pic 1: Made myself a little rig for the fins
pic 2: foreward closure. brown wires are the on/ off switch. Gonna put one of those little twist nuts on there to hold it, and ill tape it down. Blue is the main charge
pic 3: aft closure. green is the drogue charge.
pic 4: the guts of it all

starting the fins

right as i hit post my dad called me saying that i got a package. Wildman Rocketry thanks!!! 38mm von karman nose cone, and 2 bulkheads. 1 FG the other wood.

glad i bought both. FG one can go in the nose cone for the forward bulkhead. and the other can go in the coupler between the drogue bay and booster section

[Eric1]

I know thst last frame is mock up but be sure to secure the battery cable with small ziptie or electrical tape. I forgot too on a prototype flight, battery disconnected at apogee. Fortunately, The main deployed at top!

Nice work

[edwinshap1]

I know thst last frame is mock up but be sure to secure the battery cable with small ziptie or electrical tape. I forgot too on a prototype flight, battery disconnected at apogee. Fortunately, The main deployed at top!

Nice work

oooh thanks for the tip, will do

that thing is a PITA to get in though lol.

just thinking of the best way to mount the fins. like should i add big fillets or not? and then the question of how to FG the whole fincan when im trying to get the FG to such tight corners and keep it there...ideas guys :O

[blackjack2564]

Don't need tip/tip if fillets are done right.

Use JB weld to tack on & for fillets.[If you don't think reg. epoxy is enough] Only need a dowel or PVC pipe 3/4 in. diameter to get correct fillet radius.


Don't have any tip/tip on my 38's & I fly pretty extreme.

See the instructions on Wildmans site for the BlackHawk 38 or build thread. [same thing really]

[edwinshap1]

Don't need tip/tip if fillets are done right.

Use JB weld to tack on & for fillets.[If you don't think reg. epoxy is enough] Only need a dowel or PVC pipe 3/4 in. diameter to get correct fillet radius.


Don't have any tip/tip on my 38's & I fly pretty extreme.

See the instructions on Wildmans site for the BlackHawk 38 or build thread. [same thing really]

is most of that fillet volume really useful for strength? +I'd rather use tip/tip cuz i'm using 1/16" ply+a layer of FG. also im just worried about landing on that playa too hard.

[Pantherjon]

I would just go with regular fillets...If your worried about a hard landing, use a bigger chute!

[edwinshap1]

I would just go with regular fillets...If your worried about a hard landing, use a bigger chute!

using a 30" x type ultra, unless a car runs over it i guess u guys are right. wasn't thinking about larger fillets, but i can use a piece of plastic pipe or something, and kevin's idea of acetone instead of denatured alcohol...whats teh difference?

finally got bulkhead eyebolts, pics soon!

[edwinshap1]

updates: set the bulkheads. 1 in the base of the nosecone, 1 in the coupler between the booster and drogue bay.

Glued in the NC and packed it for the first time. tight fit, but with the masking tape i need, it holds in fine and tight, i'll have to ground test it at some point before the launch.

still gotta get the lugs on. I'm seriously thinking of cutting the rail lugs in half (they're pretty long, and i dont need that much support for the rocket.

comments/concerns?

Pic 1: lower bulkhead
Pic 2: Upper bulkhead epoxied into the nose cone.
Pic 3: Lower bulkhead epoxied into coupler
Pic 4: Payload bay/Ebay+nose cone assembled. Very tight fit to get the whole parachute in looseishly.

i don't have any way to add shear pins since they'd be attached into the E-bay coupler. I won't need very much friction on the lower payload so im sure some friction on the upper +a little more pressure should pop the parachute off pretty easy.

Edit: mass of rocket w/o motor is a little less than 1.625 lbs, which is near optimum for my L2 cert

didn't know the mass of the nose cone, and i didn't factor in epoxy/addl. bulkheads and such. all in all, this build is coming together. gotta get the other 2 fins on, then fillet time...then paint/decals

[blackjack2564]

and kevin's idea of acetone instead of denatured alcohol...whats teh difference?

None, it's what he had, just for cleaning the residue off while pulling fillets.

Shear pins are not for e-bay coupler...rather to keep the NC on during apogee deployment. You don't want the main coming out at the top by shaking NC loose.

You should hold the av-bay in the payload with plastic rivets or screws, so there is no way it can move during ejection charge firing.

1 is all you need about an inch down from top of tube. 2-256 nylon shear pin.

If you put the fins an inch to 1 1/2inch from rear of tube [as you should have] there should not be a hard hit problem.

[edwinshap1]

i'll have to do some testing, but i have a feeling that the main chute bay will not come off during drogue deployment since the drogue will probably pop with .2 to .3 grams of BP, and the chute one is pretty tight with the tape i put on it.

gotta wait til the april roc launch to test it though, but if all goes as planned i'll be L1 and possibly L2 certified on april 9

Update:
i finally got the bulkheads on (pics above) so i was able to finally glue the booster to the lower payload and i ran into difficulties/good time. I figured that since hte booster section was more snug, i would push that in first, then push the payload section onto the other side. I got the booster section about 2 inches on, and it was literally too tight to do anything lol. So i cut my losses and put the other side on. i had both hands on it and was jumping up and down, so like 200 pounds, and it was a major pain to get them together, but they are now.

Bad news, in case the booster section separates (no chance in heck lol), then it'll be bad, but the extra 2 inches or so allows me to use the CTI 6 grain reloads in addition to 38/720 aerotech reloads.

pics to come

[edwinshap1]

crazy jim you've been such an asset. i bought some JB weld for the fillets, more for the viscosity than the heat resistance, but that was a definite factor. this rocket is starting to look beautiful

gah, gotta upload pics...info below:

Pic 1: fins tacked on with 5 minute zpoxy. going to use JB weld for the fillets.

also, i post after pics mainly cuz i don't have 5 hands to do everything with lol, but if theres something thats slow setting i can take a pic