2023-04-05 - Electronics/Avionics mounting clarity

Change Description <Filled out by requestor>

ICARUS

Electronics/Avionics mounting clarity

Megan Spee

Atlas#0263

Description of Change

Updating the architecture document to include clarity from mechanical side on electronics mounting locations and available channels to route wires on the ICARUS airframe.

Implementation

Implemented via finalizing new wiring diagrams and including additional details about frame in arch doc.

Reason for Change

Provide a consistent and up-to-date version of electro-mechanical integration on the ICARUS frame, and to supply a knowledge base for project-associated members who lack background in ICARUS frame creation/design.

Priority

Medium

Impact of Not Responding to Change

Will be unable to move forward with clarity on electro-mechanical integration

What Groups, People, Sub-teams Need to be Notified?

Mechanical
Electrical
Sysint

Change Impact

Additional Parts/Resources Required and Costs

Me, @Megan Spee to provide diagrams of ICARUS frame with sufficient detail for EE to ‘take it from there’. Will be in contact with technical director and associated subteams

Impact on deadlines

Less than 1 week

Alternatives and Recommendations

N/A, either I do it or someone else does

Comments

Part 1: Changes to Architecture

Motors

All specs in Propulsion.

Notes:

lift motors are angled 3 degrees inwards along the roll axis to achieve better yaw authority in flight
lift: locking motors to hold props when in fixed-wing configuration
push motor is mounted on a spar protruding from the rear cross spar

Wings

2.4 m wingspan, 40 cm chord, and the thickest point is 4 cm. XPS insulation foam (pink, 2” thick, cut in slices by the CNC). Separated into 4 main sections - one outer wing on each side, and one mid-wing on the inside of the h-frame and the outside of the fuselage (also on each side). There is a wiring channel running through the entire wingspan, up till about 15 cm from each wingtip, with a cross-section of 5.0x2.0 cm.

Split ailerons, 2 on each side. each aileron is 38 cm long with 6 cm width. One servo drives each aileron. These are printed from lightweight PLA and any joints between prints were fused with a soldering iron. The ailerons are attached by gorilla tape to the foam wings.

There is 1 spar (25 mm outer diameter, CF twill tube) running through the entire wingspan (it is not continuous. It splits at the H frame intersections). There is a locating stabilizer a few cm distance from the main spar, and it is 15 mm outer diameter, non-twill CF. It runs through the entire mid-wing and fuselage, and then about 10 cm into each of the outer wing. It does not continue into the wingtips.

Notes

each wing has vector nav antenna slot (with grounding panel) about 10 cm from the end
the wings are at a 3 degree angle of attack
the servos are located in the bottom of the wings
the wing profile is NACA64A210 airfoil

Tail

The tail is comprised of 2 sections, the horizontal stabilizer (contains the elevator) and the vertical stabilizer (2 of them, containing the rudders). Side-to-side length of horizontal stabilizer is 83.5 cm, and it is 31.5 cm front-to-end. Each vertical stabilizer is 28 cm tall. The tail is made from the same XPS 2” pink insulation foam as the wings and is CNC’d to create its shape. Horizontal stabilizer is about 1.85 cm thick at its thickest point.

There are 2 CF spars running through the tail, each of them 13mm outer diameter and through the entire length of the horizontal stabilizer. There are no spars in the vertical stabilizers. The tail is connected to the H-frame with 3D-printed inserts (CF PETG filament), which the horizontal spars attach to.

The servo motors are located in the horizontal stabilizer. There are 4 holes (2 on either side of the horizontal stabilizer, very close to the vertical stabilizers. They are oriented so the servo long axis is front-to-back with the drone, and the servo horn’s axis is directly upwards. The servos closest to the rear of the plane operate the elevator. They should be in sync. The servos farther from the rear of the plane each operate a rudder. The elevator is 78.5 cm long and 9 cm front-to-back. The rudders are 22 cm tall and 8 cm front-to-back. The elevator and rudders are made of lightweight PLA and all joints are fused using a soldering iron. Hinge on the elevator is gorilla tape similar to the wings - hinge on the rudders is a 3d printed insert with a metal rod (from a marker flag) running through the rotating axis.

Notes

VTX antenna is mounted on the left side of the tail, flat on the horizontal stabilizer
RFD antenna is mounted on the vertical stabilizer in a way that does not obstruct airflow
FPV camera 3 is mounted on the vertical stabilizer in a way that does not obstruct airflow - OR a satellite dowel, which will be defined later if necessary

Fuselage

Fuselage is 95 cm long, including end-to-end of the nose and tail cones. The fuselage is approximately 40 cm diameter (may vary). One nose cone (the tail cones are identical) is 18.1 cm long. The nose cones are made of CNC’d insulation foam, grey, 4” thick. The fuselage is attached to to the H-frame via mounting blocks that join the cabin skeleton and the 2 main cross-spars. These blocks are made of water-jet and bent aluminum bolted to 3D-printed shaft collars, and with 3D printed spacers that double as clamps to help locate the 2 cross-spars.

The cabin skeleton is a rectangular prism made of 10 mm outer diameter CF twill tubes with corner joints made of CF PETG filament. Panels between this frame are flat, thin carbon fiber layups. The skeleton is the main structural component of the entire fuselage. (Everything else on the fuselage can be considered not structural). The passenger cabin is contained in the rear majority of the skeleton, and contains 6 seats for 6 barbie dolls. The seats are bolted into the bottom panel of the passenger cabin. The battery compartment sits in the front section of the fuselage and contains 4 6s batteries and 1 3s battery. It is separated from the passenger cabin by a flat CF panel.

Access to the nose cone is achieved with a circular cutout in the front cabin skeleton panel. Access to the undercarriage of the fuselage is achieved with a wiring channel in the bottom of the battery compartment. The top of the battery compartment is open, and the top of the passenger cabin is closed (it is the avionics bay base plate).

The fuselage skin is a flat 1 layer carbon fiber layup sheet that bends around the cabin skeleton in the shape of a cylinder. It is attached to the cabin with velcro, which is mounted to XPS 2” foam ribs glued to the cabin panels. These foam ribs will need to have wires routed through them to access the sensor stack on the bottom of the fuselage. The cabin door is a part of the skin, disconnected from the rest of the skin. It folds down from the top of the fuselage. The bay door steps are lightweight PLA spray-painted black, connected to the lower part of the cabin skeleton with 3D printed CF PETG hinges.

The avionics bay is 5.2 cm at its tallest point. It contains flight electronics. It is a fiberglass mold, and will be removable/ accessible relatively easily when the plane is on the ground. It covers the entire cabin skeleton and provides access to the entire open-top battery compartment. It is not waterproof. It is translucent.

The undercarriage of the fuselage contains a stack of sensors (FPV camera, lidar, optical flow, and an isolated-system samsung galaxy (this phone is not very relevant to the wiring. It will connect to a USB C port in the pixhawk, and charge via the same one). Wires will be routed through cut holes in the foam ribs. Tape may be used to secure the electronics in place.

The landing gear is CF tubing in small pieces joined with CF PETG filament shaft collars. The skids are made of polycarbonate slices. The landing gear is attached to the cabin skeleton with shaft collars. Each skid is approximately the length of the cabin, and is bent upwards at the front.

H frame

The main frame of ICARUS is comprised of 3 rectangular hollow CF twill tubes and 2 circular hollow CF tubes. The maximum length of these rectangular tubes is 120 cm, running from the front-back of the frame, and the 3rd rectangular spar is cut to 83.5 cm and runs left-right behind the wings. The main 2 tube spars (25 mm OD and 15 mm OD) run through the wings. (see Wings section for more detail).

Notes:

No wires will run through the CF tubing
motors are mounted to the H frame with dedicated mounts
wires will need to be covered with tape

Part 2: Diagrams

Important notes:

All dimensions in cm unless otherwise labelled
The entire fuselage can shift backwards and forwards, depending on center of mass. This means the wing spars have an undefined location over the avionics bay
The first 2 diagrams include the OLD PUSH MOTOR LOCATION. please see the last 2 drawings as reference for the updated push motor location.
the antenna mounting locations are subject to change (in angle, exact position). This includes the RFD and VTX antennas only.