first scratch build... where to start??

[Rex R]

a simple rular will likely get you in the ballpark . some things like the centering rings, I measured estes Ring stock (which may or may not match yours) big thing for you right now is to get the simulation reasonably close and get some practice running the program. you can worry about getting more accurate as your rockets get bigger .
rex

 

[Jake]

Ok, so I'm gonna try and summarize some of this up
I measured my cones shoulder base, and it came to around 1.5. and I now that the body tube is 1.595 (because I looked it up ) So is It ok to just put the nose cone base as 1.595? And if so, do you think there will be a problem with using this nose cone with the rocket?
Also, you said that you changed the parachute from a 14 to a 12". Would there be a problem to launch it with a 14"?
And about the launch lugs, I looked again and you have two of them at a 1/4" inch a piece. Is that all you need?
Thanks for all your help guys!
Jake
edit: I edited my origianl copy of the rocket, and tried to put a engine block in. I took the motor out, put the block in, and then added the motor. Instead of the motor being pushed out the end of the rocket like yours, it shows the rocket INSIDE the block. Does any one know what im doing wrong??

edit #2: does any one know what a regular plastic nose cone (like on that would come on the mean machine) is made out of? Or what it would be considered int OR?

 

[Rex R]

Estes noses are usually polystyrene. on the motor selection menu there is an option for motor overhang...set this to 0.25". I'll let you in on my observations even if you weighed each part (and did a mass over ride) the rocket as built will be heavier than the sim (OR doesn't account for glue) and the cg probably will not match, as long as the shape and length of the nose match reality, the cp location will be fairly close to reality and that is the important bit. right now I'd say that you have everything you need to build the rocket just print out the fin template and maybe the tube marking guide. once it is built and painted, weigh it and use that weight to determine chute size(generally you want a descent speed about 10mph). after that 'worry about the cg location.
ayup that is all you need for launch lugs for that size/mass rocket . and to think that we used to use paper and pencil(maybe) to design rockets .
rex

 

[Scotty Dog]

I dont really remember what I put in the box.
I do know that the NCs in the box fit/go with the BTs.

I think this (PNC) is the one your talking about Jake.

Estes PNC-60NA Plastic Nose Cone. Estes #072057
Length 4.75" Diameter 1.64"
Fits a standard BT-60 body tube

Used on the following rockets

1301 Storm Caster
1760 Load Star
1908 Scrambler-2
1922 Marauder
1944 D-Region Tomahawk
1982 Transtar Carrier
2022 Warp II
2056 Patriot
2070 Bail Out!
2086 Tomcat
2156 Prowler

 

[Rex R]

thanks Scotty. that should ease Jake's worries.
rex

 

[Jake]

Yes, both your reply's have eased my worries! Thanks guys allot for your help, and sorry if I seem a little over concerned about some things
I think I've worked all the bugs out. Here's an updated version. View attachment The dominator edited (Jake's).ork
what d'ya think?
Jake

 

[qquake2k]

I like the design. Are you really using cardboard for the fins?

 

[Jake]

I like the design. Are you really using cardboard for the fins?

Thanks! ummmm.. no. I don't know how that happened.... Just switched it to balsa!
thanks for catching that!
Jake

 

[Rex R]

and for your next assignment class...build .
rex

 

[Jake]

That thread is on its way!!!
Jake

 

[Scotty Dog]

I cant open those .ork type files.

 

[Scotty Dog]

and for your next assignment class...build .
rex

What's this, are we skipping over the "GLUE" chapter and going straight to the build chapter? :lol: :wink:

 

[Rex R]

Scotty: are running open rocket? and are you trying to open the '.ok' files by double clicking them? if yes then, well I have not found a way to associate .ork files w/ OR to enable that. I have to use the file menu in OR to open them.
rex

 

[Jake]

What's this, are we skipping over the "GLUE" chapter and going straight to the build chapter? :lol: :wink:

HAHA I guess so It's gonna be pretty simple.... all I'm using is epoxy and a little bit of wood glue to hold the skins on the fins.

 

[Jake]

I cant open those .ork type files.

Uhh... I think Rex R will be able to help you better than I.... I just download the file, then go to OR, open up the file menu, click 'open', and then select the .ork file.... You probably already know all that though....
Jake

 

[Jake]

Well, forget the new thread, I'll just post my build progress in here. To start with, I'm calling this rocket... THE DOMINATOR.

So I began by gathering all the material. 1 Nc-60 nose cone
1 Bt-60 body tube
1 shock cord
1 engine mount (got it pre assembled)
1 launch lug
1 sheet of 1/16" balsa
1 parachute


I then cut the BT down to 10 1/2". (I read in a article about a guy making a rocket the same size and using a 10 1/2" Body tube, and it worked out on OR)


I then cut and sanded the fins. I cut them according to a previous fin template I had.


Next I cut out pieces of 40# paper a little bigger then the fins. Painted on some wood glue, and glued the 'skins' on.


A couple days later I mixed up a batch of 30 min. epoxy, and glued in the engine mount.

I fear I may have used a bit on the heavy side of epoxy though....
I had a little epoxy left over, to I glued in the shock cord as well.

And attached it to the nose cone.



Next step: Attach the fins :y: (which always takes me a while)
Jake

Edit: I also CA'd the inside ends of the body tube.

 

[Jake]

So now I have a couple questions concerning painting and fillets.
I'v seen some guys make a tape border around the fins to keep the epoxy in that area while making fillets. Do you guys now what tape will stick to the BT, but still come off and not take and paper form the tube with it? I'm gonna try a couple different types, just to 'speriment on my own, but just though I'd ask y'all.
Also, is there any thing I should do to the body tube, and fins before priming/painting? I've seen people talk about wood filler and different things? Any advice is helpful!
Jakester

 

[Rex R]

since I keep it on hand, 3m blue tape for delicate surfaces. if the appearance of the tube spiral bothers you, bondo brand glazing & spot putty will work...me I just live with the spirals, too much like work to fill in something that I can't see from 3' away .
rex

 

[Jake]

since I keep it on hand, 3m blue tape for delicate surfaces. if the appearance of the tube spiral bothers you, bondo brand glazing & spot putty will work...me I just live with the spirals, too much like work to fill in something that I can't see from 3' away .
rex

Ok cool Yeah I was thinking either that, or masking tape. I agree about the spirals, just thought I'd ask to see if there was another purpose that people did that.

 

[Scotty Dog]

Ok cool I agree about the spirals, just thought I'd ask to see if there was another purpose that people did that.

Crazy thing that filling is.
When I dont, I wish I did.
When I do,I wonder why?

Anywhoo- Looking good.
Just a reminder on attaching the shock cord mount thingy,make sure its down in the tube fer-enuf so its doesnt get in the way of the NC shoulder.
Whats the deal with the "Tube Cutter"?
Is that a window shade cutter or a home made thing?

 

[Jake]

Crazy thing that filling is.
When I dont, I wish I did.
When I do,I wonder why?

Anywhoo- Looking good.
Just a reminder on attaching the shock cord mount thingy,make sure its down in the tube fer-enuf so its doesnt get in the way of the NC shoulder.
Whats the deal with the "Tube Cutter"?
Is that a window shade cutter or a home made thing?

Yeah.. I may just skip it this time, but I might use the filler 'next time'.
Thanks! I did make sure that it was low enough.
The deal with that tube cutter..... nope, not a shade cutter.... nope, not home made (by me at least)
That is a tool that was given to me by the guy who created it. Its original purpose is for cutting firework tubes. But I found it also works great for our BT tubes. Here's a link to it. I know... not cheap, but its a great tool.
It does take a little time to get used to though, I suggest practicing on some junk tubes first. It has the tendency to want to create a spiral cut, but with a little practice, it works like a charm!
It also helps to but something inside of it (like a dowel rod or pole, or something of that sort) to keep the tube from caving in during the cutting process.
Jake

 

[Jake]

Hey guys! back with more questions!
I'm wondering about my fins. I've seen people shape there fins (square outboard edge, rounded leading edge, and tapered trailing edge) and I'm curious.. is this important to do even on a small rocket like what I'm building? Or is it not that necessary?
And for attaching the fins, my usual way of doing it is to put a bead of epoxy on the root edge of the fin, and on the pre-marked fin line, and place the fin onto the tube. Eyeball it to make sure it's strait, and once it's dry, apply the fillets. Is there a better of of doing this?
TIA, Jake

 

[Rex R]

well I was going to let you find your own way...but since you ask .
Fins
for this model you main limiting factor is not aerodynamic but rather the motor. what you do with the fins isn't going to affect the max alt much maybe 50' from square edges to teardrop fin shape. making sure they are all straight and true is your best bet for performance.
attaching said fins; for low power I like to run a thin bead of wood glue(I like Elmer's wood glue) along the root edge, rub it in and let dry, once it is dry run another thin bead along the root edge and attach to the bt. the glue will grab within 30 sec.s. after about 2 minutes you can attach the next fin. one can do 4 fins in under 10 minutes . give the fins oh, say 2 hours to dry. after that I like to apply a thin bead of wood glue (1/16" wide) spread that with a 000 brush. when that is nice and dry I get out the titebond no-drip(aka trim and molding) and do all the fillets. easy clean up, no fuss w/ mixing.
rex

 

[Jake]

Thanks for the insight rex! I've built kits before, so I knew that flat edged fins would work, but I had seen people shaping their fins, so I thought I'd ask
Thanks also for the fin gluing tips!
Jake

 

[Rex R]

here is one for you, for sub sonic rockets, you can reap most of the benefits of the 'fancy' streamlined airfoil by simply rounding the leading/trailing edges of the fins. as an added bonus the rounded trailing edge is less prone to landing damage than the 'knife edge' streamline .
rex

 

[Jake]

here is one for you, for sub sonic rockets, you can reap most of the benefits of the 'fancy' streamlined airfoil by simply rounding the leading/trailing edges of the fins. as an added bonus the rounded trailing edge is less prone to landing damage than the 'knife edge' streamline .
rex

Thanks rex! I might try that!

 

[Jake]

Just marked the lines for the fins and launch lugs, and glued the launch lugs on.

 

[Jake]

PHEW.... Glad that's over! I've got to get a fin guide made... Or I'm gonna go blind trying to eye ball these fins :eyepop: Any one have a good set up for that?
Anywho... Beside painting, the rocket is done!
I made up a little stand for gluing the fins on.

And then,,,,, I glued them on.

And added fillets.

For all of this I used 30 min. epoxy.
About an hour ago, I went out doors and primed it.

About to go paint it gold!!!
I'm probably not gonna put decals on it until I know it flies properly
Thanks again to all of you for help, troubleshooting, and to Scotty Dpg, for parts
I am about to upload some pics of an Estes express kit I'b building (again, thanks Scotty!)
and soon, I want to attempt making a dual cluster rocket... Will see

 

[Jake]

two steps forward.... one step back. Keeping us humble.
My final paint job came out, well, not as good as I would have liked. Lots learned for the next paint job.

I sanded the paper skins on the fins, and I must have sanded to much, because the paper started to form little hairs. And the more I tried to get them off, the more came Not to self: DONT SAND THE SKINS SO MUCH STUPID!!

I also had trouble with the paint can. It didn't want to spray, and then it would burst out, creating a long drip I was able to clean it up some what, but not perfectly.

 

[Rex R]

note to Jake: it is best to not sand paper skins* before getting at least two coats of primer on them. then you're not sanding paper just paint.
*you can sort of get away with light sanding...IF you apply water thin super glue to the paper other wise you're going to get the dreaded fuzzies.
rex