Big Tube

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cryoscum
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Re: Big Tube

Postby cryoscum » Mon Jun 24, 2013 10:36 pm

Hi Jase

The maverick's tube was also 6" dia, but not as long as this. It was probably 1.5m in length. I've not since that build had a design that needed a light weight airframe as much as that. Missile designs are inherently unstable due to their very nature (the patriot being a notable exception) and hence they end up having a lot of ballast in the NC. To give the rocket decent performance you thus have to make everything else as light as you can.

If I need to I will do such a tube again, but for more traditional rocket designs (i.e. not missile designs) there really is no point and the effort significantly outweigh any gains. For now simple solid composite tubes suit the projects I do and they're quick, easy and cost effective.

Cheers
N
AMRS L3 | NAR L3 | QRS 089 | MDRA 224
AMRS Technical Advisory Group

Total impulse for 2016: 32,458 Ns (thus far)
Total impulse for 2015: 84,231 Ns
Total impulse for 2014: 40,757 Ns
Total impulse for 2013: 62,927 Ns

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Re: Big Tube

Postby cryoscum » Tue Jun 25, 2013 4:11 pm

I think there have been fewer than 20 posts today which, for this forum, is ridiculously low. So here's a pic of a tube made on that mandrel.
2.4m long, 6" diam, 3.2mm wall thickness, 8 layers of 295 gsm twill e-glass and the rest 165gsm S-glass.
1.jpg
1.jpg (98.37 KiB) Viewed 2535 times


And this is what it's for:
2.JPG
AMRS L3 | NAR L3 | QRS 089 | MDRA 224
AMRS Technical Advisory Group

Total impulse for 2016: 32,458 Ns (thus far)
Total impulse for 2015: 84,231 Ns
Total impulse for 2014: 40,757 Ns
Total impulse for 2013: 62,927 Ns

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Re: Big Tube

Postby str8up » Tue Jun 25, 2013 4:45 pm

And the Chinese name for this rocket is, "Ho Lee Sheet".

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Re: Big Tube

Postby ROCKet STAR » Tue Jun 25, 2013 4:59 pm

:shock: Definitely not going to miss this!!
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Re: Big Tube

Postby Jase69 » Tue Jun 25, 2013 6:11 pm

Cryo, question.....

Just because I'm as dumb as dogsh*t, can you please explain to me what the smaller tube in then nose cone (drawing) is for. Being a newbie something I just can't work out for myself :?

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Re: Big Tube

Postby cryoscum » Tue Jun 25, 2013 8:00 pm

You're here, so obviously NOT dumb as dogsh*t. You could've been spending your time on that other deadsh*t forum, but you're not. Proof positive.

Anyway, I usually put a big-as-I-can-fit tube inside the NC, simply to fit electronics. In some cases, such as the more extreme sort of flights, this is all you have to work with and the NC, with extended shoulder, becomes the whole lot, i.e. storage for drogue, main, AV bay etc. See: http://www.ausrocketry.com/forum/viewtopic.php?f=10&t=3659 In my (modest) opinion, any sort of rocket that starts seriously pushing the limits will find itself being mostly motor and a lot of frenetic stuff crammed up in the front. The above link just demonstrates an early version of how to cope with it in a 4" rocket intended for a 98% N-motor.
Do I have all the answers? No.
Are we on the right track? You bet!

Mike P did it and hence proved that.


Cheers
N
AMRS L3 | NAR L3 | QRS 089 | MDRA 224
AMRS Technical Advisory Group

Total impulse for 2016: 32,458 Ns (thus far)
Total impulse for 2015: 84,231 Ns
Total impulse for 2014: 40,757 Ns
Total impulse for 2013: 62,927 Ns

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Re: Big Tube

Postby Fadge » Tue Jun 25, 2013 9:28 pm

Looking good Nic.

What are you going to call this beastie, and where are you going to launch it?

Regards,
Mark
QRS # 109
TRA # 14178 (L1)

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Re: Big Tube

Postby cryoscum » Tue Jun 25, 2013 11:40 pm

Hi Mark

Neither answers are currently known, but I can say that I have it on excellent authority that flights above 24,500' (and into the thirties) are, in fact, very possible at multiple Australian Tripoli launch sites and, with good lead times and a sufficient level of prefect-butt-kissing, it should be very achievable :)

And, for the few non-believers out there, this will just be another hurdle successfully traversed, just like the pile of previously 'insurmountable' hurdles already in our rear-view mirrors...

Cheers
N
AMRS L3 | NAR L3 | QRS 089 | MDRA 224
AMRS Technical Advisory Group

Total impulse for 2016: 32,458 Ns (thus far)
Total impulse for 2015: 84,231 Ns
Total impulse for 2014: 40,757 Ns
Total impulse for 2013: 62,927 Ns

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Re: Big Tube

Postby Jase69 » Wed Jun 26, 2013 6:29 am

cryoscum wrote:You're here, so obviously NOT dumb as dogsh*t. You could've been spending your time on that other deadsh*t forum, but you're not. Proof positive.

Anyway, I usually put a big-as-I-can-fit tube inside the NC, simply to fit electronics. In some cases, such as the more extreme sort of flights, this is all you have to work with and the NC, with extended shoulder, becomes the whole lot, i.e. storage for drogue, main, AV bay etc. See: http://www.ausrocketry.com/forum/viewtopic.php?f=10&t=3659 In my (modest) opinion, any sort of rocket that starts seriously pushing the limits will find itself being mostly motor and a lot of frenetic stuff crammed up in the front. The above link just demonstrates an early version of how to cope with it in a 4" rocket intended for a 98% N-motor.
Do I have all the answers? No.
Are we on the right track? You bet!

Mike P did it and hence proved that.


Cheers
N


Thank you Sir.
Ps. Lov the vid

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Re: Big Tube

Postby cryoscum » Tue Jan 21, 2014 7:33 am

Trying something new every so often is a good thing, whether it works out or not... It's extra sweet when it does work out!

Given that I have a bit of workshop space for the first time in years, I thought I'd start messing around with my 10" mandrel again. The last time it was used was for the big Sledgehammer. At the time I could only reliably make the tubes about 1200mm long and getting it stiff enough was a pain as you had to lay up mountains of cloth (I think the Sledgehammer BT had 8 or 10 lineal meters of 165gsm per tube to make up a modest 2mm wall thickness. It was obviously strong enough, but the tubes still had deflection due to the high OD.

So, a core matting solution would make a lot of sense, but doing a 10" tube using Corecell would be a nightmare, given how I struggled with the 6" version (http://www.ausrocketry.com/forum/viewtopic.php?f=10&t=2631&hilit=maverick&start=50)
An overseas friend put me in contact with a supplier of a cork (!) interlayer that I had to give a go. The roll arrived last week containing the 3mm matting, 1250 wide & 26m long. It costs about 1/4 of what the Corecell does, has about the same density, but is very pliable. It easily bends around almost any mandrel, unlike the Corecell! Why not just use Soric? It would work, but it absorbs resin like a mofo, so much so that it is a favourite amongst composite manufacturers using it as flow matting in prepreg applications. A Soric tube could weigh DOUBLE the nearest equivalent just due to the high resin content. The cork interlayer is much better in this sense, not as good as Corecell, but the ease of use makes it a better bet for tubes.

So to test drive this, I made a tube consisting of 3 layers 295gsm, 1 layer 3mm cork matting and another 3 layers 295gsm.
1.JPG
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Wax paper in place:
2.JPG
2.JPG (39.65 KiB) Viewed 2378 times


Inner layers of glass and cork interlayer in place:
3.JPG
3.JPG (37.22 KiB) Viewed 2378 times


Just used micro pore tape to join the cork. The pores in the tape allows resin to go straight through it once layed up.
4.JPG
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All glass and peel ply in place:
5.JPG
5.JPG (37.67 KiB) Viewed 2378 times


Stripped off mandrel. Pulled it off with one hand! I was surprised :)
6.JPG
6.JPG (37.6 KiB) Viewed 2378 times


Some specs:

Length 1800mm
ID 251mm
OD 262mm
Wall 5.5mm
Weight 6.4kg (2.55kg glass cloth, 0.52kg cork, 3.33kg resin)
Overall density 790kg/m3 - about the same as radiata pine timber!! It would easily float in water.

The equivalent tube in solid composite would weigh approx 14kg...

It seems to have been a successful experiment. After heat treating it I'll give it a bit of a structural workout (without actually breaking it).
Total manufacture time was 3.5 hours and the material cost is around $150.
AMRS L3 | NAR L3 | QRS 089 | MDRA 224
AMRS Technical Advisory Group

Total impulse for 2016: 32,458 Ns (thus far)
Total impulse for 2015: 84,231 Ns
Total impulse for 2014: 40,757 Ns
Total impulse for 2013: 62,927 Ns

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Re: Big Tube

Postby ROCKet STAR » Tue Jan 21, 2014 8:54 am

Nice! Looks as though that cork material worked out really well.

I guess this means that there is another 10" diameter beast on the horizon? :D
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Re: Big Tube

Postby kopius » Tue Jan 21, 2014 9:00 am

Very nice work as always Nic. Great to see new ways of making such big tubes. Looking forward to the ext build thread that this will r used on ;-)
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Re: Big Tube

Postby Scoop1261 » Tue Jan 21, 2014 9:14 am

Maybe you should test the theory on a larger mandrel ........ say 12" ..... :wink:

Seriously though ....... It certainly looks the part, and if past work is anything to go by, will prove to be extremely successful!
Why Limit Yourself?

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Re: Big Tube

Postby vk2icj » Tue Jan 21, 2014 9:15 am

I thought this was how you make your rocket longer,, dang now I gotta try something different


cryoscum wrote:Heheh, looks like that trick just works everytime! It also works for friction fitted motors with too much masking tape!

The real truth is that THIS is the reason why you need to build your rockets ultra-strong :)
1.jpg

2.jpg
73 de vk2icj ..

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Re: Big Tube

Postby cryoscum » Tue Jan 21, 2014 9:52 am

For those interested, I had a look at the Soric specs (http://www.nuplexcomposites.com/australia/files/images/stories/pdfs/fgi_manual_pdfs/CoreMaterials.pdf)

A tube matching these same dims would be made up as follows:
- total of 6 layers 295gsm glass = 2.54kg
- 1:1 resin/cloth ratio for the glass = another 2.54kg
- 3mm Soric XF3 (lowest resin consumption) = 190g per sqm = 0.275kg
- resin for Soric matting = 1.5kg per sqm = 2.16kg

Total = 7.5kg (versus the 6.4kg with the cork, even though the cork weighs 520g versus the 275g of the Soric)
The Soric tube would have an overall density of 925kg/m3 (versus 790kg/m3)

Hence it is clear the Soric leads to a heavier final product, but not DOUBLE as I incorrectly mentioned earlier. It's more like a minimum of 17% heavier... This percentage will be higher if you use the other Sorics that absorb more resin, but give a better surface finish. With the XF the cells are bigger, leading to the final product showing the hexagonal pattern through. I'm sure this is manageable, but only if you love sanding and you may have to put more glass on the outer surface to compensate for what you sand off! :?
The cork gives a surprisingly good surface finish. I hate sanding. Passionately!!
AMRS L3 | NAR L3 | QRS 089 | MDRA 224
AMRS Technical Advisory Group

Total impulse for 2016: 32,458 Ns (thus far)
Total impulse for 2015: 84,231 Ns
Total impulse for 2014: 40,757 Ns
Total impulse for 2013: 62,927 Ns


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