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Integrate tipping bars to current motor mounts
Find dimensions for tipping bars and consider the propellers
Figure out the plate that will provide support to the 4 legs on the bottom
The length for the legs is not a constraint
Look at excel file for cycle capacity for each leg length
Author: Camilo Artigas Alos Date:
Revision #1
My focus with this revision was to keep it parametric and easy to modify. This is because a lot of the parameters needed have not been determined so far (angle of landing gear, length of cf tubes, etc…)
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Within this assembly, the angle of the landing gear and the length of the carbon tube can easily be modified within the text file in PDM. I’ve tried it many times and it’s worked so I apologize in advance if you’re greeted with a lot of errors if you try to do so.
For this model I chose an angle of 20 deg and I did not change the length of the cf tubes. I also made a copy of Pegasus' assembly to see how this design would look on the drone.
This leads me right into the support plate. I decided to not design the actual plate, but rather how I thought it should be mounted. This is because the size of the payload is currently being determined by Conall Kingshott. Within this design I implemented heat inserts into the bottom part of the landing gear, which I think would be a viable option if the plate also went around the cf tubes.
Disclaimer: The support plate has a lot of sketchy in-context relations within the assembly and is not parametric as the rest of the design, so suppress its assembly if you’re going to play with the parameters.
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I also have decided to integrate the tipping bars when I have feedback with this revision, this way I will be able to do so efficiently.
Next steps are of course to get feedback, but also settle on the parameters, evaluate the way to attach the support plate to the drone and start printing.
Author: Conall Kingshott Date:
Overall, this looks really good. I think the modifications at the top seem really solid. Everything up here I’m happy with after my first look.
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The black 3D printed foot part here also looks really good to me. The big thing I think we’ll need to work on is the center plate. First note is that the angles it goes at right now to fit around the tube aren’t something we can manufacture right now. We would normally make a part like this on a water jet, but a water jet can only cut straight up and down. There isn’t a good way to make a cut like this on a mill or drill press. It’s not too big of a deal as you could just make it a 2D shape with clearance, but it’s worth thinking about.
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As far as what you have mocked in as the center plate right now, I don’t want to comment too much because it’s a placeholder. What I will say is that we may need to consider CF tubing for these cross braces because we are likely going to have a good bit of compressive force on these cross-members when landing. CF isn’t very good in compression, but it’s light and we can get tubing which will give a much higher moment of inertia which should help. My concern if we did out of thin aluminum like this is that it would bow, and thicker aluminum would be too heavy. I think we would want to allow the 3D printed foot to include mounting spots for CF cross-braces. Then you’d probably need to make a square for the cone to fit in with an open bottom, kind of like this, where red is CF tube and blue is the water collection mechanism.
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The thing here is that it would make it way easier to have the cone at the bottom be the fixed thing, and the center column be the moving part. The only way to make the cone easy to have as the moving part would be to move the whole crossing section about 7” higher so it’s above the cone. The issue with the center column being the moving part is that it basically means you need to be pushing it down instead of pulling up the cone which would be more awkward to do with a servo, given the servo likely needs to be above the whole assembly for packaging and water protection issues.
As far as the exact path forward on that particular issue, I think I need a bit of time to think about it because it’s not immediately clear to me. Hoping to talk to some combination of Alison Thompson Smile Khatri and Evan Janakievski at the work session this weekend to figure out a path forward.
Author: Alison Thompson Date:
This looks great so far! I agree with everything Conall said above so I’m not gonna focus on that stuff here. From my quick review + some bay convos during work session:
I think we will want two configurations of the bracing since we are moving forward with designing 2 solutions for the payload and each will be different
For the cone version, bracing should be at a height specified by Conall’s cone design to mount the fixed part high enough
For the pump design we are thinking of mounting the submersible pump on the brace, with the brace on the bottom like you have and the tank mounted to the arms within the CF plate perimeter (this shouldn’t interfere with what you are doing
we will probably want a more circular or square design for the brace in order to allow us to dump the water without loads of deflection when the water hits the brace
I think we have a 30 degree angle in Conall Kingshott ‘s geometry sketch, if you can CAD the bucket and make an assembly with main and the bucket so we can see how this fits, I think that would be helpful in determining the angle we should use
Author: Camilo Artigas Alos Date:
Bay Convo #2
Notes:
Pump does not have to be at the center (this helps with square bracing)
Use CF tubes for bracing
Copy old pegasus leg joint for anti-tipping bars (COMP24 folder)
Keep everything parametric still
Use Conall’s method for tipping bar length
Author: Camilo Artigas Alos Date:
Current State
Settled on 20 degrees
Added tube support at the bottom, will need 2 tubes total
Need to adjust the height of the support, currently the pump goes through the floor
Will start working on anti-tipping bars
From now on, I will create one assembly/component configuration for each payload variant
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Author: Camilo Artigas Alos Date:
Payload CAD Review Notes
Increase clearance from top of the barrel to bottom CF plate to 80 mm
Make sure cavity is big enough for electronics cables in new motor mount for atp
Author: Camilo Artigas Alos Date:
More Updates
Anti-tipping bars finished and fully integrated into motor mount with cavity for cables.
The manufacturing of the main pieces of the landing gear is done, only the cf members left.
Drawings for the cf members will be done soon, need to rethink pump mounts as well. I also need to adjust the dimensions where the 3D printed part meets the aluminum bracket (0.4 mm) since it was a tight fit.
Added depth limiters due to vague bucket dimensions, they reach out until the OD (22”). This helps meet the clearance with the scoop servo, which is currently around 90 mm.
There’s a 1mm gap between the end of each landing gear hole and the tube, as advised by Conall Kingshott.
The angle of the gear is still 20 deg.
