Faster? Well, kinda :)

Discussions on high/extreme altitude and mach busting rockets.

Moderator: Moderators

User avatar
cryoscum
STOP... Hammer Time The Prodigy
STOP... Hammer Time    The Prodigy
Posts: 1802
Joined: Wed Oct 06, 2010 2:54 pm
Location: QLD, NSW & VIC

Faster? Well, kinda :)

Postby cryoscum » Sun Dec 25, 2016 12:47 pm

I'm always interested in ways to speed things up and, in this case, what I'm doing is hardly new or particularly cool, but it certainly does speed up the manufacturing process. I'm waiting for the new nylon 3D printing filament to arrive and thought I'd mess around with the PLA filament that I have. For those that have done some reading on this, you would know that ABS and PLA are the most common materials used for 3D printing and they are very similar in many ways (e.g. strength, printing temp etc.). PLA has a somewhat higher ultimate tensile strength than ABS and is also made from corn starch, making it about as eco-friendly as these things get (ABS ultimately comes from crude oil).
Making PLA fin cans will certainly work for HPR in many cases, but I think not for high performance flights. How would that be achieved? Let's find out...

The purpose of the exercise is to devise a 3D printed fin can that survives a Mach 2 flight.

I would surmise that you need the following things to achieve that:
- a fin and fin can design that optimizes the survivability of the fins through correct leading and trailing edge design, correct thickness, shape, flutter calcs etc.
- use the material that gets you the best possible chance, i.e. nylon (higher melting point than ABS or PLA, much better layer-to-layer adhesion, an ultimate tensile strength much higher than any of the rest), use additional materials to ensure structural suitability of the whole, i.e. be ready to have internal reinforcing for the fins.
- calculate likely aerodynamic heating and deal with it. This may or may not be a problem, depending on the rocket's flight profile, as long as it does Mach 2. For this stainless steel shim again comes to mind, but I'm guessing it may not be necessary...

So, while I don't have the nylon filament yet, I thought I'd fine tune the process of transferring 3d models from my usual CAD software to the somewhat finicky software that interfaces with the CubePro Duo. From Revit to Cubify Design to CubePro, i.e. from *,rvt to *.sat to *.stl seems to work OK. Too much is lost using *.dwg or *.dxf formats...

So, doing a hypothetical propeller:
1.JPG
1.JPG (21.02 KiB) Viewed 2060 times

2.JPG


Now down to business: a 38mm fincan with the fins in a standard 30 deg / 60 deg config with each fin tapering to the tip, both faces properly airfoiled and the root chord flaring to create a "fillet" of sorts.
3.JPG
3.JPG (14.44 KiB) Viewed 2060 times


During the 4 hour printing (200 micron layers, solid internal structure):
4.JPG

and the end product:
5.JPG

Seems stiff enough for most club flights...

This is now the 54mm version with fin thickness, tapering and airfoiling modified after the 38mm test drive:
6.JPG
6.JPG (22.91 KiB) Viewed 2060 times

It is currently printing at 70 micron layers, solid internal structure.The finer resolution and higher density means a 20 hour printing time, but at least it is machine time, not my time. I'll be making turkey while its busy doing that - i.e. the very reason I'm pursuing this method :)

For those interested, I'll keep you posted on the progress.

Merry Xmas to the entire Rocketry Family! :)
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

RedPhenix
Parachute Packer
Parachute Packer
Posts: 44
Joined: Mon Mar 23, 2015 11:00 am

Re: Faster? Well, kinda :)

Postby RedPhenix » Sun Dec 25, 2016 2:07 pm

Hey Nic

You just need one of those NASA printers that work with titanium, and unobtaineium. Seriously, does anyone want to bet against consumer 3D metal printers In the next half doEn years?

Cheers
TRA L3 #14659, AMRS L3 # 183

User avatar
cryoscum
STOP... Hammer Time The Prodigy
STOP... Hammer Time    The Prodigy
Posts: 1802
Joined: Wed Oct 06, 2010 2:54 pm
Location: QLD, NSW & VIC

Re: Faster? Well, kinda :)

Postby cryoscum » Sun Dec 25, 2016 2:55 pm

Agreed Noel! The time will come. Just look at laser cutters. 10 years ago only large corporations had them!
It seems to me that 3d printing (by way of heat fixing layers anyway) only really works with materials that have poor heat transmission properties, hence why it works with stainless steel and titanium, but not with aluminium, copper or silver - a real pity, as the titanium cost will always remain a problem and SS is too heavy...

Man, will we be building some crazy stuff with a titanium printer :twisted: !
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

User avatar
CATO
Mr Smiley
Mr Smiley
Posts: 1979
Joined: Thu Dec 24, 2009 6:20 pm
Location: Sydney, NSW
Contact:

Re: Faster? Well, kinda :)

Postby CATO » Sun Dec 25, 2016 6:37 pm

Nice Nic....
"In thrust we trust"

AMRS 21 L3
TRA 07459 L3

Impulse:
2018: 14,767 Ns (44% N)
Ns 17: 5,973; 16: 34,558; 15: 35,955; 14: 6,016; 13: 10,208
PB - Gorilla N2717WC, H: 10,260', S: 1.14M

User avatar
cryoscum
STOP... Hammer Time The Prodigy
STOP... Hammer Time    The Prodigy
Posts: 1802
Joined: Wed Oct 06, 2010 2:54 pm
Location: QLD, NSW & VIC

Re: Faster? Well, kinda :)

Postby cryoscum » Mon Dec 26, 2016 11:17 am

Here's the 54 version now. Wondering if I should make a single-fin on a sector of the tube for mechanical testing (i.e. pull on it until it comes off). The 3D printing process relies on an imperfect bonding of the layers. This is very different from say an injection molded part where you can be pretty sure the density is uniform throughout. Food for thought...
1.JPG
1.JPG (55.54 KiB) Viewed 2028 times
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

User avatar
cryoscum
STOP... Hammer Time The Prodigy
STOP... Hammer Time    The Prodigy
Posts: 1802
Joined: Wed Oct 06, 2010 2:54 pm
Location: QLD, NSW & VIC

Re: Faster? Well, kinda :)

Postby cryoscum » Mon Dec 26, 2016 7:55 pm

I did another one in red ABS this time, but what a waste of time that ended up being! The ABS is significantly less rigid, softer and downright weak. Not sure how it is that the numbers are similar, because the actual truth seems to be very different. I think I could probably crush the tube with one hand, i.e. certainly not something I would stick a 6G 54mm motor into!

So, the lesson: When you don't have Nylon, use PLA rather than ABS...
1.JPG
1.JPG (39.08 KiB) Viewed 2015 times
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

User avatar
OverTheTop
It's only money...
It's only money...
Posts: 2659
Joined: Sat Jul 21, 2007 2:20 pm
Location: Melbourne, Australia

Re: Faster? Well, kinda :)

Postby OverTheTop » Mon Dec 26, 2016 8:11 pm

Looking forward to seeing how this performs!

As for printing a sample part for testing, everything I have read about composite parts says that the only way to determine part quality is to destructively test. 3D printed parts are not quite as bad, but still very dependent on process stability. If you have a stable process the sample should be a good indication of the final strength. I assume you have a heated build volume?

You could even print two test coupons and treat one with acetone to see what the difference in strength is.
TRA #13430
L3
"Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

air.command
Astronaut
Astronaut
Posts: 1910
Joined: Mon May 14, 2007 11:18 am
Location: Sydney, Australia
Contact:

Re: Faster? Well, kinda :)

Postby air.command » Mon Dec 26, 2016 9:21 pm

Interesting post Nic and Merry Christmas! I too am looking forward to what results you get as I have also recently purchased a 3D printer and started printing with it some deployment mechanism components and camera mounts, I am keen to see where the technology can be used on rockets. Do you think there would be any issue with heat from the motor case affecting the fin can's integrity?
Crop Circles: ... just a bunch of guys looking for their rockets ....

User avatar
SpaceManMat
Astronaut
Astronaut
Posts: 2098
Joined: Mon Dec 15, 2008 9:56 pm
Location: Brisbane

Re: Faster? Well, kinda :)

Postby SpaceManMat » Mon Dec 26, 2016 9:26 pm

Liking this build tread...

cryoscum wrote:Agreed Noel! The time will come. Just look at laser cutters. 10 years ago only large corporations had them!
It seems to me that 3d printing (by way of heat fixing layers anyway) only really works with materials that have poor heat transmission properties, hence why it works with stainless steel and titanium, but not with aluminium, copper or silver - a real pity, as the titanium cost will always remain a problem and SS is too heavy...

Man, will we be building some crazy stuff with a titanium printer :twisted: !


Actually the cost of titanium is tied to processing not so much availability. So there is potential for cost to come down.
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

User avatar
cryoscum
STOP... Hammer Time The Prodigy
STOP... Hammer Time    The Prodigy
Posts: 1802
Joined: Wed Oct 06, 2010 2:54 pm
Location: QLD, NSW & VIC

Re: Faster? Well, kinda :)

Postby cryoscum » Mon Dec 26, 2016 9:34 pm

Hi George, no doubt heat from the motor is a risk, but the fin can will be isolated from the motor with masking tape. Hopefully this will be enough to avoid any significant issues...
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

User avatar
OverTheTop
It's only money...
It's only money...
Posts: 2659
Joined: Sat Jul 21, 2007 2:20 pm
Location: Melbourne, Australia

Re: Faster? Well, kinda :)

Postby OverTheTop » Mon Dec 26, 2016 9:39 pm

Actually the cost of titanium is tied to processing not so much availability. So there is potential for cost to come down.

I had a tour of the CSIRO 3D printing center a while back. The titanium powder is very expensive as the particles need to be very consistent in size, as well as mechanical properties. That can make it even more expensive than other titanium stock material.
TRA #13430
L3
"Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

User avatar
Viking
Rocket Crew
Rocket Crew
Posts: 478
Joined: Sat May 16, 2015 2:54 pm
Location: Perth WA

Re: Faster? Well, kinda :)

Postby Viking » Thu Jan 05, 2017 4:41 pm

Nice work Nic!

Sounds like you've got the software working for you but I know Cubify is limited somewhat with the filetypes that you can use.
If you ever need any other filetypes or conversions done, I have a copy of Cubify with advanced import/export support (it is a legit copy... I purchased when it was still Alibre Design, before they sold to 3D Systems)

Probably most useful to you might be STEP, Inventor and Solidworks support.
Attachments
Export.gif
Export.gif (7.54 KiB) Viewed 1938 times
Import.gif
Import.gif (14.94 KiB) Viewed 1938 times
Simon
WARS #24 / AMRS #54 L2


Return to “Higher, Faster, Further”

Who is online

Users browsing this forum: No registered users and 4 guests