YACR (Yet Another Crayon Rocket) aka "Color the Sun"

[dixontj93060]

Well after crying for days after loosing all the great build posts here at TRF (dating back to like the turn of the century for me, circa 2000), I have finally got the courage to go ahead and post another brief one. Really though the delay has been mostly attributable to the fact that I finally got to begin building a few rockets again after a move from Texas (3 years ago) and building a new house (with rocket workshop) 18 months ago.

[dixontj93060]

I first got my build feet wet with two small ones build during a couple of snow days in February so I might as well show those first (although they are LPR). One is a “strengthened” Estes Big Daddy with a funky translucent paint scheme. The second is a sport-scale, “mucho-strengthened” TLP Maverick AGM-65B. Both are built for and designed to fly E/F 24-40 reloads.

[dixontj93060]

OK, now to the HPR build. This is a scratch build from an eBay find, a 4-1/2 foot tall FOA Schwarz crayon bank. And I must say it has been a very fun build over the last 10 days or so.

[dixontj93060]

Given its non-standard diameter of 5” I attempted (for the first time) to cut my own centering rings and bulkhead. After getting the spacing right for the amount of material routed out by the bit, I was able to complete them in fairly short order.

[dixontj93060]

Oh, I also picked up some Lexan at my local Lowe’s to complete the look with transparent fins.

[Green Arrow]

Well after crying for days after loosing all the great build posts here at TRF (dating back to like the turn of the century for me, circa 2000), I have finally got the courage to go ahead and post another brief one. Really though the delay has been mostly attributable to the fact that I finally got to begin building a few rockets again after a move from Texas (3 years ago) and building a new house (with rocket workshop) 18 months ago.

I see only one problem................ Your rocket workshop is way too clean!

[AKPilot]

Well after crying for days after loosing all the great build posts here at TRF

Uh, you do know they're not lost? It was a temporary term. Check out the top of the page, upper right, under "Archive".

[dixontj93060]

You just made my day!

Uh, you do know they're not lost? It was a temporary term. Check out the top of the page, upper right, under "Archive".

[dixontj93060]

Back to the build... A very simple HPR build really, but the main issue/challenge was the plastic used for the "nosecone" and "tailcone" of the "piggy bank." The plastic is very slick and when sanded didn't scuff up well. I was worried about adherence and this was issue was confirmed after reading a record of a similar build on EMRR. So I decided to not attempt to keep the fins positioned all the way to the back of the body tube and cut into, and try to epoxy to, the tailcone. Moving the fins forward to align with the front of the tailcone allowed me to put in a third centering ring so the aft edge of the fins had a nice positive attachment point. The only issue of course was CP/CG and after looking at the additions needed for a bulkhead attachment (all thread, washers, cross pins, etc.) into the hollow "nosecone" and sim'ing a bit, I was confident that I with a little nose weight I'd be just fine.

[dixontj93060]

But even with the epoxy in the tailcone and nosecone, I intended to be very safe (I hate to repair) and added some nice yellow-tint button head screws and filled all cavities with U.S. Composites foam. A picture of the extra precaution is evident when looking at the aft end of the rocket. On 120 degree angles you see the button head screws holding in the aft centering ring, and then on alternate angles you see the pemnut entry points for the three-position plate retainer. In addition, if you look real close at about the 1 o'clock position, you see the epoxy-filled hole where the tailcone foam was inserted. To finish the back-end exposed paper and wood surfaces were painted with 1200 degree heat resistant paint.

[dixontj93060]

Again being super safe, I also added screws positioned at 45 degree angles where the tailcone and body meet. Well, actually three screws and one (aft) railbutton each at 90 degrees between the fins.

[dixontj93060]

The other worry was the epoxy in the nosecone. I used my standard nosecone attachment with a fender washer/nut assembly at the forward end held in place by two drilled cross pins (cut off, filed down and painted and you don't even notice the pins). The bulkhead normally just cinched down with another fender washer/nut assembly and left removeable for electronics, was instead epoxied in place for this design as I plan for only motor deployment and again was worried about adherence to the nosecone plastic.

If you look close you will also see an additional two metal cross pins extending across the bulkhead from approximately the 2 o'clock to 7 o'clock position and then again at the 12 o'clock to 3 o'clock position. Otherwise there is the U-bolt for shock cord attachment and some crud from overfill of the expanding foam which I hadn't yet cleaned off.

Oh, and finally the white cushiony thing is my version of the Giant Leap Fireball made from pipe insulation foam, duct tape and zipties. Works great to stop zippering on a body tube, but in this instance I am using it to protect the shock cord from the relatively sharp edges from the nose mold that were left exposed on the original "piggy bank" design.

[dixontj93060]

On the other end of the shock cord in the body tube you can see a similar U-bolt attachment and homemade "fireball" for zipper protection. Inside of body tube sprayed with 500 degree heat resistant clear automotive lacquer.

[dixontj93060]

Staying on the recovery for one more post, it is finished off with a 54" PML chute I had laying around, a Kevlar protection blanket, and the rest of the 25' shock cord.

[dixontj93060]

Well, that is about it. Very simple build really. The rocket weighed in at a bit over 5 lbs and is really made for I's and J's (up to a J420 really as, given the fin geometry and a look with Finsim, I really don't want to much exceed a velocity of 650 ft/sec), although the first flight planned for a local CIA launch on the 27th of this month will be with an H242T lobbing it up to about 950 feet (the field is limited to H impulse).

[Fade_to_Black]

Nice build. Did you make the fins replaceable? I have two crayons with clear plastic fins and have broken at least one off every other flight. The last one I built has plywood fins. Just food for thought.......

[dixontj93060]

Fred, from reading other build experiences with clear fins, it seems that most people have trouble with plexiglass or polycarbonate versus lexan which is much tougher. What material are were your fins made from?

Nice build. Did you make the fins replaceable? I have two crayons with clear plastic fins and have broken at least one off every other flight. The last one I built has plywood fins. Just food for thought.......

[dixontj93060]

I had a PM to post the Rocksim file so here it is...

[cwbullet]

Thanks for the rocksim. I have two of these to build and your help will be appreciated.

[Fade_to_Black]

Fred, from reading other build experiences with clear fins, it seems that most people have trouble with plexiglass or polycarbonate versus lexan which is much tougher. What material are were your fins made from?

Lexan may be a good option. Mine are a polycarbonate material used to make orthodontic retainers (I work in a dental lab, so they're free). Let us know how the lexan holds up, I like the look of a crayon with the clear fins. I might give it a try.

[dixontj93060]

O.K. I can fully attest to the durability of lexan and the fin can design on this rocket. Not exactly what I wanted from a first launch, but hey, sometimes ____ happens. The up part was good; turned over at apogee; separation at just the right time; uh... no chute! NO CHUTE! (stuck at end of body tube ). Here it comes and coming down fast. Big rocket; coming down fast ; landed 6 feet from me and one other lady in the crowd .

The rocket landed horizontal; and even a worse scenario for the fins--the rocket was spinning on its long axis so the fin that hit was really "cranked". I was amazed. Everything was intact. You can see a small cracking/separation of the outside fillet on the fin that hit, but when you press against it; it is solid. The only damage was a crease in the upper part of the body tube. From six feet away you can't see it. Even close you have to look. "Color the Sun" lives to fly another day .

[atticus]

Good looking rocket. I have a yellow crayon I've yet to do something with. I'm thinking a cluster.

"....it seems that most people have trouble with plexiglass or polycarbonate versus lexan which is much tougher."

Isn't Lexan just GE's brand of polycarbonate?

BTW - here's my red FAO Swartz.

[dixontj93060]

Nice red Crayon.

Actually you are right on Lexan, it is a polycarbonate, although I do believe there are different blends of polycarbonates with varying characteristics.

Good looking rocket. I have a yellow crayon I've yet to do something with. I'm thinking a cluster.

"....it seems that most people have trouble with plexiglass or polycarbonate versus lexan which is much tougher."

Isn't Lexan just GE's brand of polycarbonate?

BTW - here's my red FAO Swartz.

[dixontj93060]

First flight pic. Note distinct blue flame and "magic" fins.

[PemTech's Squeeze]

Oo...I like the "magic" invisible fins!

[dixontj93060]

A couple of recent flight pics from LDRS30 courtesy of Dave Brunsting (DAllen). Flying on an I305FJ.

[stickershock23]

The other worry was the epoxy in the nosecone. I used my standard nosecone attachment with a fender washer/nut assembly at the forward end held in place by two drilled cross pins (cut off, filed down and painted and you don't even notice the pins). The bulkhead normally just cinched down with another fender washer/nut assembly and left removeable for electronics, was instead epoxied in place for this design as I plan for only motor deployment and again was worried about adherence to the nosecone plastic.

If you look close you will also see an additional two metal cross pins extending across the bulkhead from approximately the 2 o'clock to 7 o'clock position and then again at the 12 o'clock to 3 o'clock position. Otherwise there is the U-bolt for shock cord attachment and some crud from overfill of the expanding foam which I hadn't yet cleaned off.

Oh, and finally the white cushiony thing is my version of the Giant Leap Fireball made from pipe insulation foam, duct tape and zipties. Works great to stop zippering on a body tube, but in this instance I am using it to protect the shock cord from the relatively sharp edges from the nose mold that were left exposed on the original "piggy bank" design.

Tim,

Is the bulkhead more than glued to the nose cone? (I think you explained it but I can't visualize it) I stopped using bulkheads in my crayons.

I started getting LONG Eyebolts. two fenderwashers and bolting them through just the flat tip of the nose cone. NO WOOD NO GLUE. and a good anchor point. also if you need nose weight, you can add some extra nuts on the long threaded part.

Not saying yours won't work, Just thought I'd share my secret method.

[dixontj93060]

Tim,

Is the bulkhead more than glued to the nose cone? (I think you explained it but I can't visualize it) I stopped using bulkheads in my crayons.

I started getting LONG Eyebolts. two fenderwashers and bolting them through just the flat tip of the nose cone. NO WOOD NO GLUE. and a good anchor point. also if you need nose weight, you can add some extra nuts on the long threaded part.

Not saying yours won't work, Just thought I'd share my secret method.

Yep, works fine. The flight at LDRS30 was about it's 10th.