Nike Apache Half-Scale Project

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OverTheTop
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Nike Apache Half-Scale Project

Postby OverTheTop » Thu Jun 18, 2015 4:25 pm

OK! Time to kick off the build of the next part of my master plan :)

Recently I built a half-scale Nike Smoke for my Level 3 project. So the Nike booster will be the first half of this project. Remove nosecone, insert Apache. Good to go :)

Build thread starts here:
viewtopic.php?f=6&t=4612
Flight Pics and video (my flight is at 2:30 into the video) starts here:
viewtopic.php?f=6&t=4612&start=57
Flight report and results start here:
viewtopic.php?f=6&t=4612&start=67

Back in March 2013 I started building a 1:6 scale Nike Apache. This was really the seminal event for this journey. The idea was to build a smaller version of my final project.
Build thread here:
viewtopic.php?f=6&t=3997

So, here is the Nike Apache (from “Rockets of the World” by Peter Always. Such a good book :wink: )
NikeApacheNoDimensionsResize.png

Not sure how long this will take to build, but we should have some fun along the way!

As part of this build I want to introduce some new materials and processes, if it makes sense to do so. I am not just going to keep churning out same-old same-old. No point in that at all.

As part of this journey I am making a foray into 3D printing. I can really see this being a fantastic process for both rockets and my work (designing electronics for spectrometers), so I need to get involved with it to a decent level to get best value from the new method. As part of that I need to learn SolidWorks CAD package, and although I am on the bottom end of the learning curve (and probably driving it like a Neanderthal) I think you’ll agree that my first CAD attempt on a 3D package isn’t too shabby. This is actually my first drawing from the package! I think it’s ok anyway, and that’s all that matters!
Coupler1.png

HalfSection.png

InsidesVisible.png
InsidesVisible.png (236.37 KiB) Viewed 5477 times


This has been faithfully reproduced in ABSplus (material specs here: http://usglobalimages.stratasys.com/Mai ... 5891747060 ). I have used 4MPa as my design limit to keep the stresses to an acceptable level. Overall the design is quite conservative, so the 8MPa spec for the material has a safety factor well above two in this design. A little bit heavy, but should be robust without needing to go on a diet. The 3D printing enables any features to be added, almost effortlessly, to make exactly what is required form the part, without adding extra mass or having to machine it away (or not, if it is too difficult) later. A little consideration is needed to ensure all areas are open and any support material that needs to be dissolved can be washed out. Washout was a little slow (two days) due to the long passages between the ribs, particularly around the bosses. No big deal…
20150617_160108.jpg

20150617_160131.jpg

20150617_161047.jpg


Only minor sanding (just to remove the ridges from the layering process) was needed to get a snug fit on the FG airframe tubing.

It was an interesting exercise designing the 3D part. Instead of doing a basic structure and adding (fabricating) the other details later, the design is thought about entirely up front. Features are free: you just have to design them in appropriately. Need a taper or a radius? No problem. How about a boss or two between some ribs? Easy.

I have something special planned for the fins. That will be in the next chapter of this story. Until then, au revoir :D
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Re: Nike Apache Half-Scale Project

Postby SpaceManMat » Thu Jun 18, 2015 6:08 pm

Very nice look job. Looks like it came straight out of the factory.
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Re: Nike Apache Half-Scale Project

Postby Lamp » Thu Jun 18, 2015 11:34 pm

Very cool OTT! When did you get/get access to a 3D printer?
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Re: Nike Apache Half-Scale Project

Postby martymonsta » Thu Jun 18, 2015 11:38 pm

Looks good Stewart I'm subscribed.

I had an interesting chat to the guys from stratasys at national manufacturering week, a manufacturing trade show a few weeks back, and they mentioned Ultem 9085 as another material option. Here is the data sheet http://www.stratasys.com/materials/fdm/~/media/83DA2BBEE7DE4A669CFEF6B1FCA118AA.ashx&ved=0CB8QFjAB&usg=AFQjCNGw6FC0dEshbxxYh5aUou-t3j4CHg&sig2=S6r9swSqd4DROFQwEV9BWQ it has over twice the tensile strength of ASB Plus and is flame resistant. I am unsure of how much extra it costs. If I may ask how much did it cost to get that printed and what their turn around time is.

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Re: Nike Apache Half-Scale Project

Postby CATO » Fri Jun 19, 2015 6:58 am

martymonsta wrote:Looks good Stewart I'm subscribed.

+1
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Re: Nike Apache Half-Scale Project

Postby OverTheTop » Fri Jun 19, 2015 7:11 am

Forgot to include something for scale. The large FG tube is 4" diameter.

Thanks for the link to the material Marty.

It took about 15 hours to print and a couple of days in the washout tank to remove the support material.

Sorry, but I can't reveal my source of 3D printing. :wink: I only have very limited access to it.

I have seen figures quoted for printing at places like Universities or Maker Spaces of around $6 (USD) per cubic inch for the serious printers. The cheaper machines/material are around $2 per cubic inch.
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Re: Nike Apache Half-Scale Project

Postby october sky » Fri Jun 19, 2015 1:16 pm

Very Impressive work there OTT......this will turn out to be one awesome rocket ! 8)
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Re: Nike Apache Half-Scale Project

Postby RedPhenix » Sat Jul 04, 2015 10:41 pm

Hey OTT,

Subscribed. If the smoke was anything to go by, this will be truly superb.

Can't wait to see where you take this.

Cheers

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Re: Nike Apache Half-Scale Project

Postby OverTheTop » Mon Aug 03, 2015 8:40 pm

Time for the next installment on this build thread...

To make a nosecone I have again gone for 3D printing as the method. The shape of the NC was modeled from the drawing in Rockets of the World. A set of data points was taken from the drawing and a spline generated in SolidWorks for the shape. The rest of the features were built around that definition.

Build height in the printer is limited to 12” so the NC was truncated slightly to allow for an aluminium tip, as well as getting the length into acceptable limits. I have kept the design fairly simple, with just three reinforcing ribs and four tabs for a bayonet-style push and twist attaching system.
NCSection.png

NCRearView.png
NCRearView.png (143.3 KiB) Viewed 5626 times


I was somewhat concerned about the thickness of the NC being too thin. The good thing about 3D printing is that you can just hit the “print” button again if you break it with a heavy landing :D

Next comes the bottom section of the NC, for coupling to the airframe.
NCCouplerSideView.png
NCCouplerSideView.png (230.46 KiB) Viewed 5626 times

NCCouplerSection.png


3D printing gives you such great flexibility as to how to design a part. No longer are you required to think about how to machine the part. You just design in the features you need, taking strength and functionality into account. One of the biggest steps is getting your thoughts around what material can be left out of the part and still achieve function. A machining mindset will leave more material than necessary, and this is seen in the earlier coupler part I did for the payload bay-airframe transition. If I had the chance I would do it differently next time, and save a bit of mass along the way.
Being able to design the part entirely in one piece saves so much time in manufacture. I am finding the design process far from short (still learning SolidWorks), but once completed it is almost just a matter of hitting the “Print” button.
NCCouplerInsideViewr.png
NCCouplerInsideViewr.png (202.88 KiB) Viewed 5626 times

You can see various features in the transparent view of the coupler:
• Alignment of the NC over the coupler
• Locking ramps, with additional strengthening
• Shear-pin holes
• Breather holes
• Guides for RBF pins (including tapered lead-in)
• Mounting posts and supporting webs for avionics sled
• Screwdriver access holes
• Reinforcing ribs on the base

Mated1.png
Mated1.png (128.72 KiB) Viewed 5626 times

mated2r2.png
mated2r2.png (183.79 KiB) Viewed 5626 times

NCWithSled.png


This is still very experimental for me and I am learning the capabilities of the printer as I go. A lot of how you design the parts relates to the constraints imposed by the printer (minimum feature sizes, resolution, overhangs etc) and the material strength (different in different planes). Clearances between parts (relates to printing accuracy) usually need to be determined empirically for the printer.

Here is the finished product :)
PhotoComplete.jpg


FYI, printing these two parts took over 24hrs. There was also about 48 hours in the bath to dissolve the support material.

Again I am fairly happy with progress using SolidWorks. These are only the second and third drawings I have ever done on the system, and I am refining how I use it.

I still see myself designing like a machinist in some areas. I am still working on getting rid of that habit.

Ciao for now!
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Re: Nike Apache Half-Scale Project

Postby Lister » Mon Aug 03, 2015 9:24 pm

Thats incredible. The amount of flexibility that printing brings is endless.. I am going to get a cad program and try my hand at it.. I will be watching your build for ideas not that I expect to be able to get anything like yours.

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Re: Nike Apache Half-Scale Project

Postby CATO » Tue Aug 04, 2015 7:20 am

:shock: Just wow!
"In thrust we trust"

AMRS 21 L3 RSO
TRA 07459 L3

Impulse:
2019: 14,725 Ns (44% N)
Ns 18: 14,767; Ns 17: 5,973; 16: 34,558; 15: 35,955; 14: 6,016; 13: 10,208
PB - Gorilla N2717WC, H: 10,260', S: M1.14

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Re: Nike Apache Half-Scale Project

Postby SpaceManMat » Tue Aug 04, 2015 9:08 am

Very nice!
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

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Re: Nike Apache Half-Scale Project

Postby jase » Tue Aug 04, 2015 9:15 am

Really fantastic OTT.

I recall having a chat to an American chap at Thunda about using plastics in rocketry - he kinda looked at me as if I was crazy!

I think these kind of plastics are highly suitable, particularly if used with composites. My thought was to use them as 'substrates' and then reinforce them with composite 'overlays'.

Stewart, do you think if properly prepared the ABS you are using could be reinforced with composite fabrics? For example, for fins - say for example use the 3D printed ABS to create the fin core then reinforce with composite top-layers and/or tip-to-tip reinforcing?
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Re: Nike Apache Half-Scale Project

Postby OverTheTop » Tue Aug 04, 2015 9:30 am

Stewart, do you think if properly prepared the ABS you are using could be reinforced with composite fabrics? For example, for fins - say for example use the 3D printed ABS to create the fin core then reinforce with composite top-layers and/or tip-to-tip reinforcing?


You mean like an ABS core (isogrid structure), with a CF skin, with a Vertical Trajectory System just for fun? Already planned about six months ago, and in work currently :D
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Re: Nike Apache Half-Scale Project

Postby jase » Tue Aug 04, 2015 9:53 am

OverTheTop wrote:
Stewart, do you think if properly prepared the ABS you are using could be reinforced with composite fabrics? For example, for fins - say for example use the 3D printed ABS to create the fin core then reinforce with composite top-layers and/or tip-to-tip reinforcing?


You mean like an ABS core (isogrid structure), with a CF skin, with a Vertical Trajectory System just for fun? Already planned about six months ago, and in work currently :D


:D :D 8) Oh baby, now you're talking!!! :wink:
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