Designing for Space: Notes from a repair technician. By J. Henry Ledyard.

Designing for Space: Notes from a repair technician.

By J. Henry Ledyard

About the Author

• BE Electrical Engineering• BS Physics• BA Visual Arts• Electrician (USA, AU)• Explosives, confined spaces, heights• Off Road Racer• Potential Martian

DeWalt 36v Power Drill

DeWalt 36v Battery Repair:Batteries with blown fuse.

DeWalt 36v Battery Repair:Security screws.

DeWalt 36v Battery Repair:Security bit Torx T10.

DeWalt 36v Battery Repair:Security screws and poorly sized bit.

DeWalt 36v Battery Repair:Second drill required for repair.

DeWalt 36v Battery Repair:Circuit board.

DeWalt 36v Battery Repair:Circuit board removal.

DeWalt 36v Battery Repair:Rubber encased circuit board and fuse.

DeWalt 36v Battery Repair:X-Ray of circuit board.

DeWalt 36v Battery Repair:X-Ray of circuit board – Fuse highlighted.

DeWalt 36v Battery Repair:Solution- solder wire across fuse.

DeWalt 36v Battery Repair:A design solution: pushbutton fuse.

Onsite Repairs

• Redundant critical systems• Easily replaceable systems• Standardized materials • Multipurpose tools• Manufactured onsite pats• Compatible multipurpose parts • Easy to fix systems

Standardization: Regulation

• Organized standardization• Body to define and regulate• No government affiliations• Could draw on relevant practices• NEC or AS/NZS • Fire safety or OHS• Industry designed best practice

Standardization: Theory

• Metric only• Standard practice• Standard nomenclature• Standard color code• Standardized wiring• Standardized connections• Standard size hatches• Standard size containers

RCD 20A GFCI

Acetylene

Hazard Diamond

Reactive Materials

Li + H2O

Standardization: Practice

• Metallurgy• Equipment Color Codes• Wire Color Codes• Connectors• Hardware• Software • Formats • Containers, access ways

Metallurgy

Equipment Color Codes

Wire Color Codes

Connectors1995 Toyota 4Runner

Computer Hardware

• Power Sources• Batteries• Processor• Storage / Hard Disks• Video cards• Networking cards / Connections• I/O Devices

Software

• Operating systems: Dos, Unix, Java• Drivers: USB, Buses, printers, cameras• Networks: Bluetooth, G3, G4• Images: Vector, Rastor• Displays: Web Page, Video, Images• Editors: Video, Graphics, Text• GUI: Inputs, Links, Active listening

Formats

• J-Peg, GIF, PNG• Doc, Docx, Pdf• AVI, MP3, MP4• 1080i, 720p• 16:9, 4:3, Anamorphic• 48kHz, 16kHz

Containers

Access Hatches

Design Principles

• No planned obsolescence• No disposable equipment• Repairable equipment• Accessibility• Identifiable components• Identifiable systems• Easy to maintain systems

No Planned Obsolescence

No Disposable Equipment

Repairable Equipment

Accessibility

Identifiable Components

Identifiable Systems

Easy To Maintain Systems

Nuts, Bolts and Screws

• Standardized sizes, grades• Nuts with edges• Keyed screws• No security hardware• Standardized thread pitch• Course or fine thread• No reverse threads (even fuel hoses)• Standardized plumbing• Pressure fittings• High quality materials

Standardized Sizes, Lengths

Graded Bolts

Nuts with Edges

Keyed nut design (J. H. Ledyard, 2014)

Screws

Security Bits

Thread Pitch

Not a Reverse Thread

Standardize Hoses

Standardized Plumbing

Hose Clamps

Best Choice

Gauges

Electrical

• Adjustable components (digitally/manually) • Standardized rules/colors• Connectors, compatible parts• Visible schematics • Non-destructive connectors• Robust parts in assembly

Adjustable Control Systems

NEC 2011 vs. ASNZS3000:2007Example: outlet grounding

Wire Colors

Wire Harness Connections

Wire Connectors

Robust Methods of Assembly

• Dielectric grease • Brass in place of copper• Teflon coated wire, not

thermal plastic• Solder connections• Avoid hard to trace

splices• Ensure mechanical

protection to wire in bulkhead pass through

Batteries

• Universal connections• Standardized battery configuration• Standardized voltages• Compatible with vehicles• Easy to recharge

Battery Variations

Tool Voltage Variations

Battery Internals

Cells

Chargers

12v to 5v

Heat

• View systems as interconnected• Lower weight • Use novel approaches• Transfer heat efficiently

Electric Wires on Liquid

Assembly

• Design for repair• Joints/connections critical• Identifiable connections• Plan for vibration• Plan for replacement• Plan for maintenance• Soft coat threats• Minimize sharp edges

Identifiable Connections

Loctite Nyloc

Foam

Removable Expansion

Gaskets

Liquid Formed

Wire Protection

Sharp Edge Protection

• Round edges on covers, hatches and corners• Gusset frames, ground down protruding welds• Round cable ties (new tool needed)• Use tape over cable ties (possibly reusable)• Avoid cuting steel ties, hose clamps (new tool

needed)• Wire mesh hose is high risk unless coated

Tool Design

• Start early, over many iterations• Design for ease and robustness• Standardize designs and parts• Limit size, volume and weight• Design attachments, not specialty tools• Design spacecraft for available tools• Design spacecraft for easy and quick access in

high risk environments

Repair Tools Spare Materials• Crescent wrenches• Ratchets (extensions , breaker

bar & torque wrench) • Screwdrivers (flat, Phillips &

square)• Saw (with multiple blades)• Drill (polishing brush, metal step

bits, screw bits, etc.)• Pry bar, bolt cutters• Claw, rubber & sledge hammer• Ruler, feeler gauge • Grips: Vice grips, pliers, dykes,

needle nose pliers (extended), linesman's, wire strippers, pipe wrench, hose/cable cutters

• Magnet on a stick• Box knife, pocket knife, razors

• Duct tape / gaffer tape• Electrical tape• Aluminum foil / plastic wrap• Rubber gloves• Zip ties (plastic & metal)• Tie-wire• Hose clamps• Sheet metal (beer can)• Length of hoses & wires • 2 part epoxy / JB weld• Gasket material (paper, rubber,

carbon fiber), • O-rings• Steel cable & rope• Ratchet straps

For a copy of this talk:

Speech: www.addlepated.com.au/DesigningForSpace.docx

Slides:www.addlepated.com.au/DesigningForSpaceSlides.pptx

Image References:www.addlepated.com.au/DesigningForSpaceImagesReferences.docx

Zip File Pack:www.addlepated.com.au/DesigningForSpace.zip