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Old 01-16-2011, 03:47 PM
BPRescue BPRescue is offline
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Default My First Build/ Rocket; I mean tube with fins – Big Bertha

Sorry, this one is long…

Not sure what to expect with the more advanced rocket builds, but was surprised when I received Big Bertha with laser cut fins and really all the components done for you. Clearly a basic/workhorse design targeted to ensure new modelers can make, and get by with a few mistakes without impacting flying ability. I think… First flight will tell me…

So, even though it was my first, I didn’t let my ego get in the way and built it to plan. Well, maybe not… I used the main components, but changed a few things. Keeping in mind I have the full expectation this rocket may or may not last the first launch day, I did want to try some things to see durability, aesthetics, etc. Additionally, this is my first attempt, at a hobby I have little knowledge in at this time. As such, it will be trial and error in many regards until I get more knowledge and or experience. That said, I understand some parts of design (decals) are likely incorrect, so please be easy on me. For now, I wanted to put together a decent looking model, and later I will deal with detail accuracy.
1- I tried the paper lamination over the fin thing using labels. Though I am not convinced this is the best approach to laminating the fins; it certainly appears to be the easiest; and or best chance at high quality as it leaves near perfect surface and edges. I used 3M permanent full sheet labels. I cut/sanded the fins to final design, laid the face flat on one piece of label paper. Then cut flaps for all edges of the fin with exception to the leading edge and folded them over so about 2/16” covered the opposite side of the fin face. Then, I turned the fin over, wrapping the leading edge like a hinge. I then trimmed and sanded the edges once again. I tested this on a scrap piece and found that the primer/paint sealed the edge well, so I did not bother adding CA to paper edges. Again, time will tell how good this is. I think when I get serious, I may try contact cement and regular paper since that will hold very well, without shrinkage and is certain to never fail (the glue joint anyway).
I also like this lamination thing, when you are talking about joining two fins together edge to edge; when edge grains mismatch. From woodworking I know this to be a tremendously weak joint when you try to join any end grain to another surface such as what the Estes Interceptor calls for, so the lamination will help greatly here.
2- I did use yellow glue on all joints per the instructions. Still a bit skeptical, but we will see… This is clearly a weakness and time will help me figure out when to use CA, or epoxy. I am only worried about the fins to body; but the directions outlined it. Certainly not worring about the glue side, since the glue will be stronger than the balsa, I admittedly know nothing about the body tube surface. I sanded with 400 per instructions, but just not sold on yellow glud bonding well to this; it’s the rookie in me… Another mistake may have been that the instructions said that once you glue fin to body and it is set; follow back around all the edges and smooth with finger (as similar to caulk on wall to baseboard trim). I did this, but did not want to use too much glue, making a huge joint/ adding weight. So, it may be too small. Again, time will tell and I will call it a learning experience. I see purpose, since this clearly adds a bit of structure around the circumference of the fin so the fin will be stronger. Just not sure “how much” of a lip one would desire…
3- As for paint, just used Kilz primer, sanding lightly with 400 in between coats followed by Krylon white, then red. There is no doubt in my mind that especially when using the paper lamination on the fins, I could get a perfectly smooth mirror finish by taking more time on the primer side, sanding, etc. Being my first, and expecting it to fail rather quickly, I did not take the time, so have just a hint of orange peel, but just another hour of time could really render this finish awesome. Which reminds me, does anyone attempt to fill the seem that corkscrews up the entire rocket tube? There may be a rocket I do this on; namely Saturn V if it is designed the same way.

I used Visio for this making my fin painting templates by drawing the design, printing it on a plain piece of paper, putting waxpaper on top, then taping over wax paper with wide blue painters tape. Since you can see through the thin tape (especially with a light placed under a glass cutting surface); you can easily cut the shapes with an xacto knife; then peel the tape from wax paper and place on the basecoated fins.

4- Decals. Once again, I just cannot conform. I did not like the paint job of Big Bertha, and only used a segment of decals for louvers at the base of the rocket. Probably no such animal, but I liked the way it looks… Anyway, for decals I used Papilio color laser clear adhesive full page film. Someday I will play with the waterslide decals, but I was not interested in ruining the fuser on the printer my first try… These labels seem to work ok. Decent color, printed fine, label is glossy, and surface where toner adhered is dull as expected. Clearly dye-sublimation would be much better for aesthetics and durability, but this looks passable. I will play around with an overcoat as well. Back to the Decals, I created them myself using Visio. Love the program; and use it from anything to designing woodworking/furniture, to my yard, to now model rocket decals. Since I can do them to scale, it works well. I looked at many rockets and just put together a bunch of decals that I thought would look good. I also wanted to personalize this rocket for my son; but also use a serial number thing so I can track when and how many I build. You know, for that day when I am famous and someone will bring my number 2 rocket into a Pawn shop and make $100K… Seriously though, I did want to customize to my son; as what could be better than having your name on a rocket. BTW, I did cover his name in the pics since I don’t exactly want it posted on the internet… took us a while to come up with a call sign that fit, but we call him “MadDog”. I did find some cool clipart online of a mentally deranged dog that I will put on every rocket I make for him. He loves it…
So, I am under no delusion that this thing will even fly. I did make a jig for placing the fins; even holding the rocket body horizontal while I am working on it. So, I “think” I did a pretty good job of fin alignment, but we will see. More experience, will lend to a better jig once I understand exactly what I am doing… I will test next weekend, and if all goes well, I will use it to shoot Toy Story 3 paratroopers into space for the big event. Since there will be about 12 or more kids, I fully expect the rocket to be retired on that day. I can’t guarantee tears will be absent if this is the case and sure my son will comfort me…

In all, I got my first rocket under my belt. I will make some changes in the next one, but feel more confident to work more difficult projects. Some day, I will have this stuff nailed and interested in designing my own like you guys do. But, that is way down the line and will take more brain matter than I currently poses… I have much to learn before I do that…

Which reminds me. Understanding this is Big Bertha coming from a kit. Should I still perform a swing test on this, or just bring it to the launch pad? Also, the literature says Engines: A8-3, B4-2, B4-4, B6-2, B6-4, C6-5. It does indicate first flight should be a B6-2? Can someone explain why this would be? With my limited knowledge, I would expect A8-3 to be less powerful; hence burn time is less, as is altitude. Is the A engine a bit underpowered, potentially rendering the more powerful B engine more stable and hence the first flight recommendation? B6-2 has two seconds after burn to which it will deploy the chute. I admit, I am not sure I understand why you would want 2 seconds, vs. 3 or even 4; other than giving it a little time to arch and slow down. My guess is, it wants just enough thrust to get this rocket into a safe altitude before it starts to track a human target…

BTW, not sure if you guys do this, but I kept a file folder with the build instructions, templates, etc. I traced the fins on a blank piece of paper; and even drew exact scale in Visio as to use if I break a fin. Figure, this could help down the road when I do want to design my own. Am I the only psycho that does this?

Anyway, sorry so long. I am excited to get this to the launch and see if I actually made something I can call a “rocket”…
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  #2  
Old 01-16-2011, 04:06 PM
BPRescue BPRescue is offline
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Default More

Here is a pic with the laminated fins… Notice, you can see my centering lines along the edge of the fin. I did it this way so I can place the edge of the fin along the entire line as to ensure it is perfectly strait. The instructions indicated to center the fin off of this line, but you can only see the front, so I did not like it. The only catch is you really have to pay attention and place all fins exactly the same; on the same side of the line; otherwise you will be in trouble.

Also is a pic of my quick and dirty jig. Gives me a perfectly vertical/center reference on multiple tube sizes. Time will tell if I need something better. I would like something that I can specify which tube size; even slide both supports per my need. That will take more time than I was looking to spend on this one. Just wanted to build a rocket; you know… Worked fairly well for the fins; though I am certain I will come up with better…
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Last edited by BPRescue : 01-17-2011 at 11:28 AM.
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Old 01-18-2011, 02:36 PM
Scotty Dog Scotty Dog is offline
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Default Center lines only PLEASE

. The only catch is you really have to pay attention and place all fins exactly the same; on the same side of the line; otherwise you will be in trouble.
OHHH boy..Someday Ill post" WHY " I work with center lines only. You can use a marker (felt) to put a mark on the base of the BT on the very end or just inside it. I wonder how people line up fins that are airfoiled, sanded to an odd shape going by the sides of them????? Also, if your really into being perfect, if the fin is just a little thinner on top or bottom, lining them up with the sides will put them off. Ceneter is center is center is center . Get it! Got IT! This info comes from an old pipefitter named Scotty Dog.
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Old 01-18-2011, 06:35 PM
BPRescue BPRescue is offline
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Good points on center and it makes sense. I did not consider fins being thinner front to back because I would NEVER make such a mistake… I can now see the potential issue. I will use your method of marking the end of the tube; it sounds like a good idea and will be much better.

Yeah, I figure it would have taken one misstep for me to put the fin on the wrong side as to ruin the project. I thought it was sound and decided to do it since I have an Interceptor and I noted the 8” fins immediately warped per the way they glue together. Easily solved once you glue it to the body. So, at this point I will use your centering method, but may also add a couple lines on each side for reference as to get it strait. Most fins shouldn’t have this issue, but this is thin and long…

Thanks for the tip
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Old 01-18-2011, 06:54 PM
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tbzep tbzep is offline
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Just mark the lines like a carpenter does so he doesn't forget which side to butt up a 2x4. Put an "x" on the side the fin should go when you draw the fin lines. Simple, quick, easy, and you get the benefit of using that line to get the fin perfectly straight.

Just don't forget to move the launch lug over 1/16" so it will still be centered between the fins.

BTW, that's a great looking Bertha!
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Old 01-18-2011, 07:20 PM
BPRescue BPRescue is offline
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Quote:
Originally Posted by tbzep


Just don't forget to move the launch lug over 1/16" so it will still be centered between the fins.





Hah! Phhhhhhhhhhht; whatever.... Move the launch lug over... Who would forget to do that...???

Ya saw my pic, didn't ya? I kinda forgot... Hope it does not affect the flight... Good news, I won't forget ever again...
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Old 01-18-2011, 08:30 PM
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That's a beautiful BB!

This is the ONLY BB I've ever built as an adult. It was a commissioned job for advertising and was launched on a TV commercial. Gordy did the decals!
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Old 01-18-2011, 08:41 PM
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tbzep tbzep is offline
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Quote:
Originally Posted by BPRescue
Hah! Phhhhhhhhhhht; whatever.... Move the launch lug over... Who would forget to do that...???

Ya saw my pic, didn't ya? I kinda forgot... Hope it does not affect the flight... Good news, I won't forget ever again...


Actually, I didn't notice it. I've just forgot myself, then had to cut them off and move them.

It won't affect the flight at all. As long as they are fairly straight, you can put them just about anywhere. I've had kids glue them on so crooked that the rocket was pointed way off axis, but they cleared the rod just fine.
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Old 01-18-2011, 09:12 PM
BPRescue BPRescue is offline
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Quote:
Originally Posted by jeffyjeep
That's a beautiful BB!

This is the ONLY BB I've ever built as an adult. It was a commissioned job for advertising and was launched on a TV commercial. Gordy did the decals!



I like your BB; great looking rocket. The entire time I was building mine, I kept telling myself; “less is more” trying to keep some form of class. But, this is for my 4 year old where “more is more”, or is it “more is less”… Or is it “less cost less”… Less next time; but likely more cost… Ah heck, now I’m just confused… I thought this board was supposed to help…

BTW, what kind of decals did you use?
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Old 01-18-2011, 09:39 PM
soopirV soopirV is offline
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Quote:
Originally Posted by BPRescue
I like your BB; great looking rocket. The entire time I was building mine, I kept telling myself; “less is more” trying to keep some form of class. But, this is for my 4 year old where “more is more”, or is it “more is less”… Or is it “less cost less”… Less next time; but likely more cost… Ah heck, now I’m just confused… I thought this board was supposed to help…

BTW, what kind of decals did you use?


VERY nice first build! I'm gonna go out on a limb here and guess that you're some form of engineer...way technical and detail oriented (did you really build a JIG for your first build?? I'm also intrigued with your use of Visio- I've only ever used it for swimlanes and process maps...your idea is so much more...vital)

Although...my Bro-in-law has a PE in Civil Engineering with a pretty high-level job in Fed DOT and builds rockets just so he can stuff the largest engine for that diameter into it. Could be the stress of the job, but I think he's just a rocket sadist.

Regardless, welcome to the hobby- I got restarted when my oldest was 3, so I don't think anyone REALLY beleived that I was "doin it for the kids". Now that they're older it's just the perfect excuse to have a "blast" Hope you and yours enjoy it as much as we have- we need MUCH MORE of the younger generation gettin' the bug.

EDIT - I've said this before on other posts, but it's particularly poignant here: MY first rocket with my Dad was the BB. I'd still have it if it weren't for my older brother cleaning out the attic after he bought Mom and Dad's house while I was away at school...take care of this one, it'll last a lifetime (mine was stuck in umpteen trees, landed on school roof and had several ejection failures, but kept on ticking, until it met the dumpster!!)

PS- No tears, please!- Dad is still around and launches with me often, and brother is still an a-hole! Further, it was the first rocket I RE-built with MY sons!

PPS - said A-hole brother sleeps with his wife in the same room our parents used...'nuff said!!
Cheers!

Dave

Last edited by soopirV : 01-18-2011 at 09:49 PM. Reason: Adding one thought
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