Remote Station Engineering - Structural Systems

This page is maintained with specifications for mechanical components which are the current best-practices employed by UNAVCO in Polar Permanent GPS Station designs. Specifications are subject to change as the design evolves, however the most current design will reside here.

Technical Notes

Complete lists of permanent station components and tools, and a weight calculator, are maintained on the Documentation page.

Structural Frames for Rock Surfaces

Component	Photo	Manufacturer	Part Number (click for PDF drawing)	Description	Weight (lb)	Cube (ft^3)	Why?
Rock Surface Frame (Small)		Frame construction: T & E Tech 3772 Puritan Way #9 Erie CO 80516 858-229-8478 Pipe fittings: Kee Klamp	PPS-TF-008 revB sheet1 sheet2 sheet3 sheet4 See sheet 4 for bill of materials.	For use on rock or soil surfaces. Made of 1.5" sch40 structural aluminum pipe, with cast iron slip-on pipe fittings, bolted through at joints. Accepts up to two solar panels, two wind turbines, four small or two large enclosures, comms antenna, and weather station. Breaks down into 2 pieces, will fit inside Bell 212 or DeHavilland Twin Otter aircraft. Can also completely disassemble for shipping, use Uline S-4983 box.	87	Shipping: 7 (12"x12"x84") Deploying: 24 (79"x44"x12")	Rigid, lightweight frame assembles quickly with minimal tools. Frame secured directly to rock, no guy wires. Aluminum pipe with zinc-plated fittings and fasteners resists corrosion. No stainless to avoid thread galling. Similar construction as large frame, but increased strength, more compact, and faster to install. Can be deployed with solar panels and cradle already attached.
Rock Surface Frame (Large)		Frame construction: T & E Tech (info above) Pipe fittings: Kee Klamp	PPS-TF-001 revG sheet1 sheet2 sheet3 sheet4 See sheet 4 for bill of materials.	For use on rock or soil surfaces. Made of 1.5" sch40 structural aluminum pipe, with cast iron slip-on pipe fittings, bolted through at joints. Accepts up to four solar panels, two wind turbines, four small or two large enclosures, comms antenna, and weather station. Breaks down into 7 pieces, will fit inside Bell 212 or DeHavilland Twin Otter aircraft. Can also completely disassemble for shipping, use Uline S-4983 box.	140	Shipping: 7 (12"x12"x84") Deploying: 13 (84"x30"x9")	Rigid, lightweight frame assembles quickly with minimal tools. Frame secured directly to rock, no guy wires. Aluminum pipe with zinc-plated fittings and fasteners resists corrosion. No stainless to avoid thread galling. Can elevate solar panels higher than small frame for high-drift locations.
Leveling Foot		T & E Tech (info above)	PPS-TF-002 revB	Short sections of 1.5" aluminum pipe, drilled thru to match fittings on underside of frame. Use various lengths from 4" to 14" to adjust to terrain.	Asst. bundle: 5	Asst. bundle: 1 (14"x12"x12")	Allows leveling of structural frame with simple, standard parts.
Enclosure Cradle		Cradle construction: T & E Tech (info above) U-bolts: McMaster Carr	Cradle for large enclosure: PPS-EN-001 revC sheet1 sheet2 Cradle for small enclosure: PPS-EN-002 revC sheet1 sheet2 U-bolts: 3043T73	Cradle bolts to frame with 5/16" U-bolts and washer plates. Tie enclosures down to cradle with cargo strap (see below).	Large: 20 Small: 15	Large: 3.5 (52"x28"x4") Small: 2.5 (35"x28"x4")	Positions enclosures securely on frame, and provides attachment points for tie-down with cargo strap.

Structural Frames for Snow Surfaces

Component	Photo	Manufacturer	Part Number (click for PDF drawing)	Description	Weight (lb)	Cube (ft^3)	Why?
Single Panel 2-Pole Frame		Frame construction and internal pipe couplers: T & E Tech (info above)	2-pole frame: PPS-TF-017 revA Joinable aluminum pipe section: PPS-TF-012 revA Internal pipe coupler: PPS-TF-011 revA	Simplest solar panel frame for snow surface. Each panel attaches to two 1.5" sch40 aluminum pipes, which are driven into the snow surface and secured with guy wires. Length of pipes is project-specific. If transportation allows, use long lengths of plain pipes. Alternatively, use multiple shorter lengths of Joinable Aluminum Pipe Sections with Internal Pipe Couplers.	20 (2x 10ft pipes, holds one panel)	1 (~120"x4"x4") (2x 10ft pipes, holds one panel)	Rigid, lightweight frame assembles quickly with minimal tools. Straightforward and quick to install. Relatively easy to dig out and raise above snow surface in accumulation zones.
3-Panel Tripod Frame	note: above two photos show older design with three 50W solar panels and external pipe couplers.	Frame construction and internal pipe couplers: T & E Tech (info above) Pipe fittings: Diamond Aluminum	Tripod frame PPS-TF-006 revE: sheet1 sheet2 sheet3 sheet4 See sheet 4 for bill of materials. Internal pipe coupler: PPS-TF-011 revA	For use on snow surfaces. Frame made of 1.5" sch40 structural aluminum pipe and slip-on pipe fittings, bolted through at joints. Accepts three 80W solar panels, two wind turbines, comms antenna, and weather station. Tripod folds flat to fit inside Twin Otter or 212 aircraft.	70 (for 10ft overall height)	9 (~72"x36"x6" for 10ft overall height, which breaks down into 4ft top section plus 6ft legs)	Rigid, lightweight frame assembles quickly with minimal tools. Tripod design allows rigging with minimum number of guy wires, and omnidirectional solar panel arrangement mitigates against snow buildup on leeward side. Aluminum pipe and fittings with zinc-plated fasteners resist corrosion. No stainless to avoid thread galling.
Low-speed Wind Turbine Mast		Mast construction and internal pipe couplers: T & E Tech (info above)	PPS-TF-007 revA	Accepts low-speed wind turbine mount adapter. Attach 18" diameter plywood footer to flange foot fitting. Use pip-mount saddle clamps and bolt hangers (see below) to form three guy wire attachment points.	15	0.5 (~120"x2"x2")	Locates wind turbine on separate mast away from solar panels. Overall height is site-dependent. Use single long length of plain pipe, or multiple shorter lenghts of Joinable Aluminum Pipe Sections with Internal Pipe Couplers (see above).

Enclosures

Component	Photo	Manufacturer	Part Number (click for PDF drawing)	Description	Weight (lb)	Cube (ft^3)	Why?
Large Enclosure		Enclosure: Hardigg (Pelican) Foam: R&B Sales	Enclosure: 472-463L-MM24-CEM133 Foam: PPS-EN-005 revE sheet1 sheet2 Connector Layout: PPS-EN-009 revC sheet1 sheet2	Large enclosure holds electronics board plus ten 100 amp-hour batteries. Styrofoam panels fit inside enclosure without adhesive, to create rectangular enclosure to tightly hold batteries and provides nominal thermal insulation.	Empty case: 57 With foam: 70	20 (52"x28"x24")	Rugged well-sealed "military" plastic enclosure, stackable, with large handles. Easy to handle and UV resistant. Connectors are recessed within ribs of case to reduce risk of shipping damage.
Small Enclosure		Enclosure: Hardigg (Pelican) Foam: R&B Sales	Enclosure: 472-463L-MM36-CEM133 Foam: PPS-EN-003 revE sheet1 sheet2 Connector Layout: PPS-EN-010 revC sheet1 sheet2	Small enclosure holds electronics board plus six 100 amp-hour batteries. Styrofoam panels fit inside enclosure without adhesive, to create rectangular enclosure to tightly hold batteries and provides nominal thermal insulation.	Empty case: 40 With foam: 53	14 (35"x28"x24")	Rugged well-sealed "military" plastic enclosure, stackable, with large handles. Easy to handle and UV resistant. Connectors are recessed within ribs of case to reduce risk of shipping damage.
Connector Drill Template		T & E Tech (info above)	PPS-EN-004 revC	Allows accurate thru-hole drilling for power connectors, RF connectors, and vent plug on recessed rib of Hardigg MM36 or MM24 enclosure. See below for enclosure drilling layouts.			Makes life much easier when assembling.
Vent Plug		W.L. Gore	Vent plug: PMF100444 Backing nut: M10510-008	Metal shell, teflon membrane vent. One vent plug mounted to wall of every enclosure. Standard practice for enclosures containing rechargeable batteries.	Incl. in enclosure	Incl. in enclosure	Allows slow equalization of internal/external pressure to relieve potential battery gases caused by charging system failure. See Enclosure section above for drawing of connector (and vent plug) layouts on enclosures.
Vacuum Insulated Enclosure for Polar Plateau System		Nanopore	PPS-EN-007 revF	Specialized enclosure for Polar Plateau system. Use vacuum-insulated panels to create six-sided chamber inside Hardigg MM24 enclosure. Internal chamber houses GPS/Iridium electronics board plus 9 SLA batteries or 6 SLA + 10 lithium batteries. Wires in photo are from heat pads located beneath 1/8" masonite layer on bottom of enclosure.	Large enclosure: 95	Large enclosure: 20 (52"x28"x24")	Vacuum panels offer highest insulation value among commercially available products. Electronics and batteries are contained in vacuum insulated chamber to conserve heat. Protect fragile vacuum panels with 1/16" HDPE plastic on exposed surfaces.

Accessories

Component	Photo	Manufacturer	Part Number (click for PDF drawing)	Description	Weight (lb)	Cube (ft^3)	Why?
Pipe-Mount Saddle Clamp		DX Engineering	DXE-CAVS-3CS (Saddle + V-bolt) DXE-VBK-CAVS-3CS (V-bolt only)	Aluminum saddle clamp with V-bolt attaches solar panels, wind turbines, weather stations, and Iridium antennas to aluminum tube frame. Same as stock part DXE-CAVS-3P except uses modified V-bolt (5/16-18, Grade 2 zinc-plated steel, overall length L=3.5"). Secure with washers and 5/16-18 zinc-plated nylon locknuts.	Incl. in panel	Incl. in panel	V-shaped saddle and bolt provides better grip on piping than circular. Modified V-bolts are same thread size as all other frame fasteners.
Cable Tie-Down		McMaster Carr	69855K73 (12" length, for all cable tie-downs except 1-meter monument) 69855K74 (18" length, for 1-meter monument)	Nylon-coated stainless steel reusable cable tie-down, 1/4" width. Used to secure cables to pipes.			Secure and quick to install, unaffected by UV or environmental conditions. Easily removed and repositioned if necessary.
Weather Station Mount		DX Engineering Kee Klamp McMaster Carr	DXE-CAVS-3CS Kee-Lite L68-8 7126K13 8096K63	Attaches Vaisala WXT-520 weather station to aluminum tube frame. Reverse saddle clamp and attach to flanged Kee Klamp fitting. Use 1" galvanized conduit, with plastic end fitting to reduce cable chafing.			Secure and quick to install. Set screws on flanged fitting are secure, do not need to bolt through.
Iridium Antenna Mount		DX Engineering Kee Klamp McMaster Carr	DXE-CAVS-3CS Kee-Lite L68-8 4549K606 4880K82	Attaches Aeroantenna Iridium antenna to aluminum tube frame. Reverse saddle clamp and attach to flanged Kee Klamp fitting. Use with 3/4" NPT galvanized pipe nipple, with plastic end fitting to reduce cable chafing.			Secure and quick to install. Set screws on flanged fitting are secure, do not need to bolt through.
Cargo Strap		Grainger	6A265	Secures enclosures to cradle. Hook ends fit through holes on sides of cradle.			Extra security for enclosures, especially the enclosure lids.

Anchoring

Component	Photo	Manufacturer	Part Number (click for PDF drawing)	Description	Weight (lb)	Cube (ft^3)	Why?
Rock Anchor Bolt Assembly		Rock bolt: Industrial Hardware Carabiner: Omega Pacific Bolt hanger: Petzl Chain and locknut: McMaster-Carr	Rock bolt: 20A-0W12 Carabiner: OPL6 Bolt hanger: P38150 Chain: 3363T91 x 2' 3363T91 x 5' Locknut: 95615A210	1/2" x 6" impact-expansion stud anchor. For sites with solid rock available for anchoring. Assembly with chain, carabiner, and bolt hanger is used to anchor corners of structural frame and limit movement. Order chains cut to 2 ft. and 5 ft. lengths to accommodate various rock surfaces.	2 (complete assembly)	<0.5 (complete assembly)	Simple equipment, strong and quick to install. No epoxy required, sets with hammer blows. Very secure and vibration resistant.
Rock Anchor Stake Assembly		Anchor stake and drive cap: B&B Machine and Grinding Carabiner: Omega Pacific Fender washer, shaft collar, chain: McMaster-Carr	Anchor stake: PPS-RG-001 revA Drive cap: PPS-RG-002 revA Carabiner: OPL6 Fender washer: 91117A246 Shaft collar: 6436K17 Chain: 3363T91 x 2' 3363T91 x 5'	For sites with no solid rock available for anchoring. Attach carabiner and chain to stake, secure with clamp-on shaft collar and fender washer. Assembly is used to anchor corners of structural frame and limit movement.	Stake: 7 Complete assembly: 10 Drive cap: 4	Complete assembly: <0.5	Simple, quick, and secure. Use drive cap and sledgehammer to pound stake into surface, or use stake as deadman anchor with piled rocks.
GPS cable anchor		Rock anchor: Industrial Hardware Loom clamps: McMaster Carr	Rock anchor: 20A-2Z04 3/8" clamp: 8863T13 3/4" clamp: 8863T16	Drill 1/4" hole into rock, then pound in 1/4" x 1.25" split-drive rock anchor with cable attached via 3/8" loom clamp (unsheathed cable) or 3/4" loom clamp (sheathed cable).			Used to secure GPS antenna cable to ground at sites where rocks are scarce. Simple, quick, and secure.
Snow Anchor Stake Assembly		Anchor stake: B&B Machine and Grinding Carabiner: Omega Pacific Bolt hanger: Petzl Wire rope, Gripple, thimble, swage sleeve, swage tool, wire rope cutter: US Rigging Supply	Anchor stake: PPS-RG-003 revA Carabiner: OPL6 Bolt hanger: P38150 Wire rope: W-21-006 Gripple: G-RG-06 Thimble: F-15-206 Swage sleeve: S-11-006 Swage tool: P-21-005 Wire rope cutter: P-20-C9	Anchor stake / guy wire assembly for snow surfaces. Each wire rope assembly consists of 3/16" wire rope, one thimble, and one swage ferrule. Each complete guy line consists of two wire rope assemblies, one snow anchor, two carabiners, one Gripple rope tensioner, and one bolt hanger attached to structural frame. Tension guy lines with ratcheting, lockable Gripple wire rope tensioner. Releasable mechanism with custom tool, but releasing can be difficult. Bring several spare wire rope assemblies and Gripples; cut wire and use new wire rope and/or tensioner if necessary.	Snow stake: 4 Complete guy wire assembly: 11	Snow stake: <0.5 (36"x3"x3") Complete guy wire assembly: 0.5	Simple, strong, and versatile. Pound into snow or use as deadman anchor. Gripples securely connect guy wires together and do not loosen under high winds and extreme temperature swings. Locking feature resists vibration. Can use backup swage ferrules on wire ropes if desired.