Page History

Airbrakes Engineering Notebook

10/8/2023 Getting Started

Requirements of a solution:

• Brake

• Not add weight

• Simple

• Easy to deploy

• Easy to integrate

Ideas

Calculations: 

Speed of the rocket: 1300 ft/s

Force on 14 in2 of air brakes: 866 N

10/15/2023

Goals

• Sketch multiple mechanism designs

• Try to maximize and then calculate how much area each can produce for drag

• Try to calculate how much torque is needed to actuate the system → do we need servo or motor? Does a servo/motor of reasonable size exist that can produce your needed torque (find where we could purchase said servo/motor)?

Servo motor SG90 Datasheet: http://www.ee.ic.ac.uk/pcheung/teaching/DE1_EE/stores/sg90_datasheet.pdf 

Torque of servo: 2.170 lb in

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10/22/23

Drawings and CAD

Slight change in design of current model to expand surface area

Now 2 levels of brakes that leave the rocket in 4 total leaves

Cad drawings started on the leafs, the connector and the base plate

Plan to complete CAD drawings and 3D print before next meeting 

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11/5/2023

Larger holes on connectors (3/32) - amber

Countersink under the leaves (3/16) - nicole

Change the leaf shape and add area (.625”), remove space between the inner part of the leaf and servo mount - pari

Decrease shaft cross section size (tolerance) - alex

Locknuts

Remove gap between leaves and the servo mount on the side, remove lip on servo mount - enrique

11/16/2023

5.49 in^2 (each leaf)

• 2.95 in width

• 1.86 in length

7.44 in^2 (each leaf)

• 4 in width

• Same length

11/19

Adding a top base plate (which are the rails)

Add something plastic for the leaves to sit on to reduce friction 

Make leaves longer/arms shorter 

Change the shaft to an octagon/hexagon

Edit base plate to accommodate one set of leaves instead of 2

1.75 in^3 →volume of leaf

11/30

Changing entire design basically

• Metal hex shaft (buying)

• New servo (1500 oz-in)

• Need 1100 oz-in 

• Change connector width

• ¼ in thick

• Also add spacers between connectors

• Hexagonal hole

• Add plastic tray (x2) 

• Screwed into base (threaded screws) w countersinks

• Add holder

• Make walls thinner (⅛ in)

• Servo Bulkhead

• ~ ⅜ in thick

• Have cutouts so it’s not as heavy

• Servo goes on top

• Leaves

• ⅛ in off the top lip

CAD all parts from scratch

• Due by sunday :)

PUT EVERYTHING IN “NEW AIRBRAKES” FOLDER

• Servo Bulkhead (Pari)

• Cylinder (Alex)

• Part beneath bulkhead

• Tray (Olivia)

• Frame (Juan)

• Leaves (Olivia)

• 3.5x2.5x.125

• Arms (width) (Nicole)

• 1/8  in width

• + Change middle connector to a hex shape

• New shaft (Nicole)

• Find shaft

• 2.77 in

12/03

Final area of leaves: 3.5 in x 1.57 in 

5.49 in^2 each leaf

21.9 in^2 total

Spacers + tray that leaves slide in 

PLA (3d print)

Servo

HS-1005SGT Servo
Frame, leaves, servo mount, everything else

Aluminum (machine)

6061

Cost breakdown: 

• Servo

• $479.99 (servocity)

• Servo horn (servocity)

• Sonic hub (servocity)

https://www.mcmaster.com/products/hex-shafts/material~aluminum-2/

• Shaft (⅜ in 6061 Hex Bar)

• Density of aluminum 

• .0975 lbs/in^3

Dimensions:

• Middle Connector (x4): 1.2in x 0.2in x 0.13in

• Servo Mount: 0.25in x 6in

• Hex Connector (x2): 2.3in x 0.67in x 0.13in

• Frame (x2): 6in x 1.25in

• Leaves (x4): 3in x 3.5in x 0.25in

Materials:

• Servo Mount + 2 Frames = 2.75in x 6in

• Aluminum Cylinder = 3in(height) x 6in(diameter) ($143.10) 

• https://www.mcmaster.com/7775T51-7775T518/

• 4 Middle Connectors + 2 Hex Connectors = .51in^3

• Aluminum Sheet = 3in x 3in x 0.125in = 1.125in^3 ($40.79)

• Tight tolerance 

• https://www.mcmaster.com/9057K115/

• 4 Leaves = 10.5in^3

• Aluminum Sheet = 8in x 8in x 0.25in = 16in^3 ($27.17)

• Oversized thickness

• https://www.mcmaster.com/89155K11-89155K221/

1/8/2024

KERF List 

Servo Mount: make screw holes larger - done

Aluminum Spacer: make screw holes larger - Done - 🦑

Leaves: make leaves vertically thinner (extruded part does not have to be vertically thinner) - Done, all screw-holes (larger) - Done, reduce width of leaf and extruded part - Done, bearing hole (larger) - Done - 🦑

Cylinder - Outside Casing: make screw holes larger - Done - 🦑

Frame: all screw-holes (larger), bearing hole (larger) - done

Hex Connector Middle: make hex bigger

Tray: reduce the wall thickness, reduce the width, reduce the height, bearing hole (larger) - done

The servo doesn't need to be as strong for the sustainer

Make a second airbrake with a new servo mount