3D printed nose cone launches on a Loki L1482 to 3200 feet, 725 mph
Cool . . . Now, what about 3-D printing those identical Fins and duplicating the flight ?
Dave F.
That's not a fair comparison. Anyone even remotely familiar with 3D printing knows that you cannot just copy something that is made of different material and expect it to act the same. In the case of 3D printed fins, I have personally designed fins that had carbon fiber rods epoxied into them to make them extremely strong and withstand up to mach .8 on a J motor so far (my L2 rocket). I'm confident that they would survive mach 1+ flights due to their profile and strength, a claim that I plan to put to the test soon. This is the type of modifications that have to be taken into consideration when creating 3D printable fins as it's critical to know the limits of your materials.
I agree that 3D printed fincans on L3 flights should be restricted to those existing L3 certifications as they have proved their competency and are at their own liberty to take risks (as long as it does not endanger the health of others). I hope to see people pushing the technology to its limits and coming up with new methods and techniques to make 3D printed parts comparable to their counterparts. People need to think through their designs as many 3D printed parts have a severe weakness when manufactured incorrectly such as printing in the wrong orientation, too thin of walls, etc. 3D printing is an art, never assume that you know everything or your design will fail is a way that you never saw coming.
Steve,
You posted, "However, for two reasons the board has decided to prohibit the use of 3D printed fin cans for Level 3 certification flights. The two reasons are:
1. It’s impossible to know whether the L3 candidate designed the fin can. Simply printing a shared file doesn’t demonstrate expertise or knowledge, which is what certification represents.
2. "The strength of most 3D printed parts is still not strong enough."
I have a few genuine questions : ( no "sneer quotes" )
(1) "Designing" the fin can . . . What if a flyer can prove that he did "design" it, even if it was made by someone else ? Also, the 3D printer actually "makes" things, not the flyer.
(2) A shared 3D file is essentially the same as ordering components ( not designed or made by the flyer ).
From Tripoli: "Commercially available pre-fabricated fin cans, either as part of a kit or obtained separately, may not be used for level 3 certification flights."
Shared 3D files and the subsequent printed items, made later, are not "pre-fabricated" . . . Does that give them a "loophole" ?
(3) If a flyer uses a kit, he did not design it or make the components, should kits be disallowed for Cert flights ?
(4) If the strength of most 3D printed components are not strong enough, in the interest of safety, why should their use be allowed, at all ?
Frankly, your statement, "The strength of most 3D printed parts is still not strong enough", should have been reason enough to prohibit their use, based on the safety risks alone, and not just in Cert flights !
In my opinion, I think that "plastic" fins ( as "fin cans" or individual components ), as produced by current "home 3D technology", are inherently prone to failure, especially in the upper Total Impulse ranges, and at supersonic velocities. I think that a much closer analysis and, possibly, some form of structural testing is in order, to provide accurate data, in the interest of safety.
Dave F.
That's not a fair comparison. Anyone even remotely familiar with 3D printing knows that you cannot just copy something that is made of different material and expect it to act the same. In the case of 3D printed fins, I have personally designed fins that had carbon fiber rods epoxied into them to make them extremely strong and withstand up to mach .8 on a J motor so far (my L2 rocket). I'm confident that they would survive mach 1+ flights due to their profile and strength, a claim that I plan to put to the test soon. This is the type of modifications that have to be taken into consideration when creating 3D printable fins as it's critical to know the limits of your materials.
I agree that 3D printed fincans on L3 flights should be restricted to those existing L3 certifications as they have proved their competency and are at their own liberty to take risks (as long as it does not endanger the health of others). I hope to see people pushing the technology to its limits and coming up with new methods and techniques to make 3D printed parts comparable to their counterparts. People need to think through their designs as many 3D printed parts have a severe weakness when manufactured incorrectly such as printing in the wrong orientation, too thin of walls, etc. 3D printing is an art, never assume that you know everything or your design will fail is a way that you never saw coming.
Ben,
The thread is clearly not about 3-D printed Nose Cones . . . Yet, that is where you took it. Clearly, talking about 3-D printed Nose Cones is not a fair comparison to 3-D Printed Fins.
QUOTE : "People need to think through their designs as many 3D printed parts have a severe weakness when manufactured incorrectly such as printing in the wrong orientation, too thin of walls, etc. 3D printing is an art, never assume that you know everything or your design will fail in a way that you never saw coming." END QUOTE:
What sources of public information are readily available to teach people how to safely make 3-D printed rocket fins up to, and including, Level 3?
How is the "correct orientation" determined and what sources of public information are readily available to teach people ?
By your own admission, in the last sentence of your quote, you seem to imply that 3-D printing is a less reliable method, with multiple failure modes possible . . . That, alone, should make it abundantly clear that, for most people, when it comes to 3-D printing HPR fins, the risks clearly outweigh the benefits, at this point in time !
Dave F.
That's not a fair comparison. Anyone even remotely familiar with 3D printing knows that you cannot just copy something that is made of different material and expect it to act the same. In the case of 3D printed fins, I have personally designed fins that had carbon fiber rods epoxied into them to make them extremely strong and withstand up to mach .8 on a J motor so far (my L2 rocket). I'm confident that they would survive mach 1+ flights due to their profile and strength, a claim that I plan to put to the test soon. This is the type of modifications that have to be taken into consideration when creating 3D printable fins as it's critical to know the limits of your materials.
I agree that 3D printed fincans on L3 flights should be restricted to those existing L3 certifications as they have proved their competency and are at their own liberty to take risks (as long as it does not endanger the health of others). I hope to see people pushing the technology to its limits and coming up with new methods and techniques to make 3D printed parts comparable to their counterparts. People need to think through their designs as many 3D printed parts have a severe weakness when manufactured incorrectly such as printing in the wrong orientation, too thin of walls, etc. 3D printing is an art, never assume that you know everything or your design will fail is a way that you never saw coming.
Hi, Chuck !
Nose Cones are not as much of a problem, except at MACH+ velocities. Even then, an aluminum tip would probably provide adequate protection for "most" flights.
The issue here is Fins, due to their inherent thinness, possibility of flutter, softening with heat, and possible shattering, if brittle.
Dave F.
As a data point, here is a flight of one of my rockets with 3D printed fins:
I didn't have an altimeter on this flight, but OpenRocket was predicting around 430-440 mph. The fins are thicker than they would have been with other materials, but they can be made to work if you take the material properties into account.
Yep, the fillets are printed on. There is a line of countersunk holes running down each fillet and the fins are bolted into the motor mount (which is also 3D printed). I hate messing with glue and now I can replace them if they break.Didn't even appear to wiggle. How and with what are those fins attached? Almost looks like you printed the fillets Too? Whatever methods you decided on it obviously works.
Didn't even appear to wiggle. How and with what are those fins attached? Almost looks like you printed the fillets Too? Whatever methods you decided on it obviously works.
Didn't even appear to wiggle. How and with what are those fins attached? Almost looks like you printed the fillets Too? Whatever methods you decided on it obviously works.
Hoe did they fail? I think nose cones would not fail often if they are printed with the right material and with the right infill. I have had one rocket fail with 3D printed parts. I made a BT60 rocket with a fin can and nose cone. It flew great with an F so I got brave and flew it with a G or H. The rocket flew to pieces after the body tube bent. The nose cone and fin can survive to fly again despite a hard landing.
The key to a successful 3D printed rocket for high power is the material you use to print it with and the infill. You would be foolish to use PLA, but ABS or PETG with CF should hold up to most G-J motors with the right infill.
I don't mean to be rude, but when did I ever mention 3D printed nosecones?
However, lets say an individual designs a 3D printed fin can and then as part of the construction design covers the entire fin can with a carbon fiber/composite process.
Yep, the fillets are printed on. There is a line of countersunk holes running down each fillet and the fins are bolted into the motor mount (which is also 3D printed). I hate messing with glue and now I can replace them if they break.
Was the spin intentional ?
If not, I am surprised that 3-D printing didn't provide perfect fin alignment.
Dave F.
Steve, if you print a fincan as the base and laminate it with CF of FG, would that be acceptable or no?At our monthly BoD meeting we discussed the proliferation of 3D printing. We all agree that the technology is exciting and will undoubtedly lead to some great designs. However, for two reasons the board has decided to prohibit the use of 3D printed fin cans for Level 3 certification flights. The two reasons are:
1. It’s impossible to know whether the L3 candidate designed the fin can. Simply printing a shared file doesn’t demonstrate expertise or knowledge, which is what certification represents.
2. The strength of most 3D printed parts is still not strong enough.
The board has not prohibited the use entirely. We would like it if actual launch experience with 3D printed fin cans gets reported so we can better understand what the risks are from this technology. Our L3 certification procedure will be updated with this prohibition.
Thanks,
Steve
Here's a video of the first flight of my 3D printed fincan design. It shows that if done correctly, 3D printed fincan provide unrivalled stability in flight (comparing to traditional). I plan on stressing the design with larger motors every flight, I'm pretty confident it will survive.
Link:
I love the activity on this thread, shows how exciting this "new" technology is and the many ways it can be applied to rocketry.
Wallace,
Those parts are not manufactured using 3-D printer technology.
3-D-printed components, particularly relatively thin, flat cross-section items, such as fins are known to have less structural strength and be prone to thermal weakening.
The materials they are using have already been tested by years, if not decades of use. Their inherent reliability is already quantified.
Ask yourself these questions :
(1) Is a plastic, 3-D printed fin as strong as . . . ?
(a) A Fiberglass fin of the same thickness.
(b) A Carbon Fiber fin of the same thickness
(c) An Aircraft Plywood fin of the same thickness
(d) An Aluminum fin of the same thickness
(2) Is a plastic, 3-D printed fin as resistant to thermal deformation as . . . ?
(a) A Fiberglass fin of the same thickness.
(b) A Carbon Fiber fin of the same thickness
(c) An Aircraft Plywood fin of the same thickness
(d) An Aluminum fin of the same thickness
(3) What changes to a plastic, 3-D printed fin would needed to make it as strong, and as thermally-stable as . . . ?
(a) A Fiberglass fin of the same thickness.
(b) A Carbon Fiber fin of the same thickness
(c) An Aircraft Plywood fin of the same thickness
(d) An Aluminum fin of the same thickness
Final thought : With safety being paramount in Rocketry, why would anyone, in good conscience, choose to use a sub-standard method or sub-standard materials and risk an accident ?
Dave F.
What do you use with PETG?
And not being an L3 flier, what’s so different between a 10G J boost and a 10G M boost? Torque and lateral forces on components because the parts are bigger?
Here's a video of the first flight of my 3D printed fincan design. It shows that if done correctly, 3D printed fincan provide unrivalled stability in flight (comparing to traditional).
I think that was the camera shaking due to a shotty tape job. The next flight I will be screwing the camera to the body tube so I'll see if it's really fluttering. With your fincan you really don't have to worry about fluttering anywhere close to these speeds, but it's also a lot more expensive than $5 in filament.Slight flutter at max q.
With your fincan you really don't have to worry about fluttering anywhere close to these speeds, but it's also a lot more expensive than $5 in filament.
Can't wait to see the result!Understood, and not meant as a slight to printed fin cans. I'm developing my own composite filament and single purpose printer for high temperature printing.
Enter your email address to join: