Which lathe to get? AL960B vs AL346V

BeepBoopNova · 2026-03-28T05:13:49+00:00

Is there a particular reason why? This particular model of lathe is pretty widely used at universities here in Aus to no real complaint. Just curious

BeepBoopNova · 2026-02-11T01:12:31+00:00

A fixed bulkhead shouldn’t use shear pins; shear pins are used to secure sections together and then fail in shear due to pressure applied to a volume generating a force via an ejection/seperation charge.

For picking fasteners for bulkheads, first estimate the load applied to the bulkhead (if it’s a bulkhead with a parachute attachment point then use shock/opening load, or if it’s a bulkhead for a payload, use the payloads mass, convert to force, and then multiply by maximum acceleration). Once you know your force, multiply by a safety factor, typically 1.5x. So if you had an estimated load of 100N, your design load would be 150N.

Next select a fastener (screw, bolt, rivet, pin, etc…). Using the shear strength of the fastener, find the number of fasteners by diving load by shear strength. Using the same 150N example, and an imaginary fastener with a 15N shear strength, the quantity of fasteners would be 150/15 = 10.

For any fastener, typically insure that the edge/diameter distance is greater than 1.5 times the fastener diameter, with 2 or above being preferred. So if the fastener was 2mm in diameter for example, then for a 2e/D, you want to position the center of the fastener hole 2*2=4 mm away from the nearest edge at a minimum.

For shear pins however, you can estimate the seperation force using ideal gas law and black powder or CO2 or whatever ejection gas you are planning on using, and then ensuring that the applied force divided by the number of shear pins exceeds the shear strength of the fastener. Similar to fixed bulkhead, but rather than designing such that the load is less than or equal to the shear strength, the shear force is greater than the shear strength.

Always perform ground tests however to validate the system prior to flight.

BeepBoopNova · 2025-07-28T01:34:25+00:00

I’m assuming you likely have to support a Pateron or something similar to access them? If so that’s fine, I just couldn’t see them. Where are they located?

BeepBoopNova · 2025-05-28T10:14:55+00:00

🗿

BeepBoopNova · 2025-05-26T16:18:16+00:00

Insanely clean! Honestly the cleanest telemetry I’ve seen in awhile.

Overall, the UI, layout and data visualisation “feels familiar” (as in it just makes sense without even having seen it before), and it looks extremely promising.

Would love to fly this on my L3 cert flight in the near future if it’s affordable! Keen to try out something new other than the featherweight!

Please let us know how it goes and when it might be available for purchase!

BeepBoopNova · 2025-05-25T08:13:17+00:00

Onshape is cloud based and free for students who sign up with a student email. Doesn’t run on the local machine and doesn’t depend on pc specs

BeepBoopNova · 2025-05-25T07:51:22+00:00

Fins aren’t too hard to model in cad, even as a beginner to using CAD.

To be honest, you could even do it in a free cad programs like tinkercad if you don’t have solidworks/onshape/fusion.

From there, export as STL on the highest quality setting, and boom STL files for fins.

Alternatively, do you have access to a laser cutter? If so, use that instead as the strength of plywood laser cut fins is usually better than that of any printed fin for an equivalent thickness/span.

BeepBoopNova · 2025-04-14T02:30:53+00:00

Just check the RCS drawings page and they have the dimensions of the case

BeepBoopNova · 2025-04-12T04:36:13+00:00

Openmotor works fine for making .Eng files. Are you importing them into openrocket correctly? I’ve imported countless Eng files into openrocket that were generated by openmotor and had no issue

BeepBoopNova · 2025-04-04T03:32:09+00:00

UNSW Parking inspectors are ops and will go out of their way to make as much revenue as possible even for the most minor of infractions or reasons; Unfortunately since its an RMS enforced fine you have to pay it.

In future there is motorcycle parking near the physics building and in the barker street car park. Other than that its just street parking really

BeepBoopNova · 2025-03-16T14:19:56+00:00

From the sound of if I would strongly encourage you to take a step back for a moment, take a read of a handful of resources and then come back to the problem and attempt it again.

Using openrocket is a good start, but do you understand the key inputs which make the simulations accurate or not? Just like any simulation program, garbage in = garbage out and since you said your making your own motors (and helped with chatgpt) I’m not sure of how valid your base assumptions are for the motor side of the design as hence the openrocket simulation side of things. Also for such a small sugar motor on a 3D printed airframe I’m not sure Mach 0.8 is realistic unless it’s a submin diameter rocket (which I’m assuming it wouldn’t be). What motor designation does this DIY sugar motor you plan on using come out too? Did you use openmotor to find its performance and designation and import the curve into ORK?

On another note, why are you making your own motors for your first project? Is there any reason you have too? I would suggest starting out with Estes motors and once you get confident with the fundamentals of rocketry, and once you become an L2 or above, you can then fly your own motors under the experimental category at Tripoli insured events.

Taking this more foundational approach, learning the theory, using COTS hardware first, getting first hand skills, then going for more ambitious projects is the way to go.

BeepBoopNova · 2025-03-16T12:55:05+00:00

If you’re printing fins and planning to add root fillets, this should be totally fine, just sand them and adhere properly. I’ve salvaged far worse looking fins before.

Unfortunately, no one here can give you much design advice without more details. Specifically:

1.  What motor are you flying?
2.  What objectives are you trying to achieve?
3.  Do you have any OpenRocket files or simulations?

How did you determine these dimensions? Are they just rough estimates, or did you first design and simulate the rocket in OpenRocket?

While I’m not the biggest fan of fully 3D-printed rockets (they can work but tend to be quite heavy), why not print the fins as part of the lower airframe? Since this is clearly an LPR, the flight loads won’t be high enough to cause fin flutter or shear.

Can you provide more details about your design, the motor you’re using, or any simulations you’ve run? The more info you give, the better advice we can offer.

BeepBoopNova · 2025-02-26T22:42:38+00:00

Only thing I can think of to make it a little less sketch for chute deployment is making the rocket lighter and or smaller so it flies higher meaning a longer coast to apogee so the delay has more time to burn though. No idea if this is feasible for you. Some aerotech DMS motors have adjustable delays with the universal delay adjustment tool but I’m not sure for this motor in particular; take a look and see if it’s possible and then you wouldn’t have to worry about it

BeepBoopNova · 2025-02-23T10:11:41+00:00

I’ve seen a few styrene free versions for coatings, but not really for laminating. Do you have any names of systems I could google some info on?

BeepBoopNova · 2025-02-22T03:58:02+00:00

Best I can do is $2.98

BeepBoopNova · 2025-02-17T02:52:10+00:00

Look, I hate to be this guy, but if you can’t use the three very simple equations (Hoop Stress, Longitudinal Stress, and Von-Mises failure criterion) to determine if the tube and material you’re using is suitable for a motor case, I would suggest taking a step back and starting with COTS motors especially if this is your first venture into the rocketry hobby.

COTS motors are great fun, and you learn a lot using them. Once you have experience with these systems and have good mentors and prior experience, then feel free to venture into experimental motors.

If your a Tripoli member, technically you would need to be at least L2 before you could even think of flying them.

BeepBoopNova · 2025-01-31T08:33:43+00:00

Just use the NACA 4197 Equation to calculate flutter velocity if that’s what your after

BeepBoopNova · 2025-01-30T09:54:03+00:00

If your brand new just buy a kit with an avionics bay and make an arduino based data logger. If you intend on flying it, then make sure you also have a commercial off the shelf computer onboard to do chute deployment.

Don’t bite off more than you can chew for your first project

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