MSEC 50K — Low enough to park. Tall enough to live.

Views

The whole vehicle,
in pictures.

The MSEC 50K from its right front three-quarter in the studio: the undercut nose with its fan windscreen radiating down from a hub at the roof line nearest the camera, and right behind the single front wheel the right-side door standing open with its gull-wing leaf raised and clear oak entry floor inside, the single captain’s chair visible through the fan windscreen, the long right side plain silver back to the three close rear wheels — **Front ¾, right side.** The 28 in right door opens right behind the front wheel, beside the driver.

The MSEC 50K from its left rear three-quarter on a gravel overlook above the coast at sunset: the tail nearest the camera smoothly rounded over at the roof line, curving to a set-back lower edge over the last tire, the tail smooth and solid with a low tailpipe, the three close rear wheels, a long plain left side and far forward a closed door right behind the single front wheel — **Rear ¾, left side.** The left wall solid from the tail to the 28 in left door right behind the front wheel; the solid tail with its service hatch.

Road profile, left side. 84.5 in tall at ride, 79.5 in kneeling; the left door is right behind the front wheel, mirroring the right.

Raised profile. 13 ft on four legs at camp, wheels drawn in.

The whole body from above, by day, to scale, nose at the left, the right side at the top: the cockpit, the wet room and the stair on the low floor (blue), then the deck over the three rear axles. The panels below zoom in on each end in each mode.

Driving · rear seats down

Day · open floor

Night · walls closed

The front of the cabin in three modes. Driving: two forward-facing rear seats fold down from the side walls behind the wet room line, with 37 in of legroom ahead of each, and the toilet cover is shut. Day: both seats fold flat to the walls, the stair comes down and the floor is open from door to door. Night: the bed lies across the cockpit, the shower wall is swung shut, the accordion toilet wall is drawn across behind the bed and the toilet cover is sealed for its UV clean.

A compact cabin cutaway looking forward from above the deck edge: the captain’s chair on the centreline ahead, the fan windscreen beyond, and immediately behind it beside each side wall a forward-facing fold-down seat, its plain graphite rear back shell across the vehicle against the tridem bulkhead, the backs of both seats facing the camera and their pans and occupants facing the windscreen, the right seat inside the open shower on its teak grate, the toilet between them with its cover shut — **Rear seats, driving.** Two forward-facing seats in a 75 in wide cabin, their backrests 32 in behind the chair back; the right one doubles as the shower seat. The cutaway exposes their orientation and the shared wet-room floor.

At night with the roof down, from the passage beside the stair foot: a pale grey accordion wall of narrow vertical panels drawn across from the wet wall to the left door’s jamb, closing off the toilet and the passage from the made-up bed beyond, a white toilet with its cover up on the right of the picture and the folded oak stair above — **Toilet wall, night.** An accordion wall draws 49 in across behind the bed and makes the toilet, passage and stair foot their own room.

The low floor by day with the roof raised, seen from the right door: the captain’s chair on the centreline, open oak floor from wall to wall, both rear seats folded flat against the side walls, the shower’s white two-leaf wall folded back against its fixed wet wall, the toilet on the centreline with its cover up as a backrest, the oak stair extended along the left wall up to the deck and the tall raised room above — **Open floor, day.** Seats folded, walls stacked, the stair down: from the door to the stair foot the low floor is one open room.

The shower closed: two rigid white leaves with grey gaskets swung across its front from the fixed wet wall to the right side wall and sealed to the floor curb and the ceiling, the toilet beside it with its cover shut and the captain’s chair in the foreground — **Shower sealed.** Two gasketed leaves swing off the fixed wet wall and close the shower like a door; open, they stack 2 in thick against it.

Close view of the toilet sealed: a rounded white two-leaf hood closed over the toilet onto a gasketed white floor tray, a faint violet UV glow at its seam and a small green status light, the fixed wet wall behind it — **Toilet sealed.** The hood closes onto a gasketed tray; a UV-C bar and a filtered fan run only while it is latched, and the tray washes down to the shower drain.

Side section on the centreline, to the same scale: 68.5 in over the low floor with the roof down and 144.5 in raised; the deck 49 in up with the battery, gray tank and propane gear under it.

How to read the section

The outline is the centreline profile, which is also the side silhouette: each end sweeps forward and outward from a chin set back 0.30 m to a broad rounded centre at the 84.5 in crown, blended into the roof; dashed, the raised outline, whose upper half mirrors the lower about the tip. Items beside the centreline are drawn where they stand along the body (L, R and C mark the side). In the nose: the bumper beam at 16–22 in, the honeycomb block and the two crash tubes (yellow), the heat pump over them (dashed), the windscreen along the nose from 48 to 82 in (blue) and the fresh-water saddle tanks over the front housings. The low floor is 12 in up with 68.5 in over it roof down and 144.5 in raised; the deck is 49 in up with 31.5 in roof down and 107.5 in raised. Over the low floor: the chair, both doors beside it (drawn as one opening, since they are opposite each other), the leaf rack under the roof, then the toilet on the centreline with its cover up as a backrest, the shower (R) beside it, the rear seats on the side walls (L and R) and the stair (L) climbing along the left wall to the deck. Dotted are the night beds (the twin, its top 26 in over the low floor, and the flat bunk); dashed, what rises by day: the washer-dryer, which stands taller than the roof-down ceiling and so needs the raised roof, the fridge and the table. Under the deck, in 35 in of height behind the bulkhead: the fridge (left), the gray tank (centre) and the washer-dryer well (right) at the front, a flat 17 gal fresh-water tank behind them, the inverters, the battery between the tridem housings and, at the tail, the generator with the propane tank beside it.

Day · roof raised

Night · roof down

The deck, day and night. By day, with the roof raised, the galley, fridge, washer-dryer and table rise from the floor and the couch runs along the right wall; the three rows of framed panes and the right-hand escape pane are marked on the walls. At night with the roof down everything is flush and the couchbed lies flat as the bunk under the roof hatch.

Overhead cutaway of the MSEC 50K with the roof removed, nose at the left and the right side at the top: the fan windscreen, the two front wheel housings, the captain’s chair on the centreline with open floor on both sides, a door in each side right behind the front wheels, a shower along the top behind the right door with a white two-leaf wall folded against its fixed inner wall, a toilet beside it on the centreline under a hinged cover, a forward-facing seat folded flat on each side wall behind them, a folded stair along the bottom against a solid wall, then the deck with a washer-dryer at its top front corner, a two-cushion couch along the top, a table and a galley with a hob and sink along the bottom — **Top-down cutaway,** nose at the left, right side at the top. An AI render; the plans govern dimensions.

The cockpit from behind: one leather captain’s chair low on the centreline on a hexapod base, a small steering wheel on a low dash between the two rounded front wheel housings, the fan windscreen radiating down from a hub at the top centre, open floor on both sides of the chair and a door in each side wall beside it, mirror images of each other — **Cockpit.** The chair on the centreline, open floor on both sides, a door each side beside the chair.

The raised deck seen from high at the front, looking aft over the drop to the low floor, where the toilet under its shut cover and the top of the shower wall show far below: a rail along the deck’s front edge, the stair coming up at its left front corner (on the right of the picture), a white washer-dryer risen at its right front corner (on the left of the picture), a cognac couch along the right wall with a pedestal table, an oak galley with a hob over a risen two-drawer fridge along the left wall, three rows of framed windows along the side walls and a solid tail wall — **Deck, raised, looking aft.** The 80 in couch is about two thirds of the 117.6 in deck; the stair (vehicle left) is on the right of the picture.

The entrance seen from outside through the open right-side door: the cognac captain’s chair just inside on the right, and on the left, right behind the door, a shower with a teak grate behind a fixed white wet wall, its white two-leaf wall folded back against it and a teak seat folded flat on the outer wall, a white toilet beside it on the centreline with its cover up as a backrest, and against the far wall the left door directly opposite and an oak stair with a handrail rising aft to the deck — **Entry and wet room.** In through the right door beside the chair; the shower right behind it, closed by its own hinged wall, and the toilet beside it, directly behind the chair.

Overview

One capsule.
A low cockpit, a high deck.

The body, chassis and roof are designed as one machine. Each side wall is framed like a bus side, carrying a cage of twelve-sided iron rib rings. The front wheels and crush zone hold the crash structure and the fresh water; the cockpit, entry, wet room and stair sit on a low floor 12 in off the road; over the rear tridem a deck 37 in higher is a crawl bunk on the road and a 9 ft room raised. Under the deck sit a ~400 kWh battery, the power electronics and a small boxed-in propane generator for parked use.

Body length: 19′8″6.0 m
Nominal width, under the 7 ft maximum: 83″
Clear over the deck, raised: 8′11½″
Clear over the cockpit, driving: 5′8½″

01 / Inside

Drive low.
Live up on the deck.

Three levels in one body: a low cockpit and wet room, a telescoping stair, and a deck over the tridem that is a crawl bunk on the road and a 9 ft room raised.

Read the layout

Only what SKIF needs. The captain’s chair sits on the centreline behind the front wheels, with open floor on both sides of it. The right door opens right behind the right front wheel, beside the driver, onto a small vestibule; the shower stands behind it, entered from the cabin, and the toilet beside it on the centreline, directly behind the chair. Two forward-facing passenger seats fold down from the side walls behind that line, one in the shower and one in the passage; folded flat to the walls they leave the floor open. The shower closes behind a hinged two-leaf wall, the toilet under a sealed cover, and an accordion wall drawn across behind the bed makes the toilet and passage their own room. Parked with the roof down, a 36 × 78 in twin is made up across the full width over the folded seats with an end across each closed door; the left door mirrors the right, right behind the left front wheel, and either opens over the bed. Behind the bed a passage runs along the solid left wall to a telescoping stair, which extends along that wall to the deck by day and folds onto the deck when not in use. The deck covers the back of the body over the tridem: a couchbed along the right wall lies flat for the road as the 60 × 80 in mattress of a crawl-height bunk, and the galley, fridge, washer-dryer and table rise out of sealed wells in its floor only when the roof is up. Raised, it is a 9 ft room with nothing hanging from the ceiling. The battery, propane, gray tank and electronics are packed under it, sealed from the cabin. The renders are AI concepts of this layout; the plans and end views govern. In views looking aft, the vehicle’s left side is on the right of the picture.

Cockpit and rear seats: the captain’s chair sits low on the centreline on an air-ride stage and a hexapod of six stroking struts, belts built into the seat, with open floor on both sides: 68.5 in of headroom against the 58 in a 6 ft 3 in driver needs at the low setting. The two passenger seats face forward, one on each side wall behind the wet room line, their backrests on the faces of the first rear wheel housings: 18 in wide, the pan 18 in up, 37 in of legroom ahead of each pan and 63.9 in of headroom against 60. Folded, the pan swings up and the seat lies flat on its wall, 4 in thick. The right seat stands in the shower, a teak-slatted pan that is also the shower seat; the left one is in the passage beside the stair foot. They share floor with other things on purpose: the right seat folds before the shower wall can close, the left before the stair comes down or the toilet wall is drawn, and interlocks enforce it. Facing forward they need three-point belts anchored to the frame, a harder frontal-crash case than the rear-facing seats they replace.

Entry and wet room: the right door, 28 in wide and 72 in tall raised, opens beside the chair onto a 32 × 25 in vestibule. The shower stands right behind it, entered from the cabin: a 24 × 25 in pan recessed 1.5 in into the floor, 66.7 in at its centre with the roof down (a seated shower) and 142.7 in raised. A fixed wet wall runs full height along its inboard edge, and two rigid 12.65 in leaves hinged on that wall’s front end close its front, gasketed on the pan curb, the wet wall and the ceiling; open, they stack 2 in thick against the wet wall and leave a 23.3 in opening, which is also the way through to the passage, since behind the chair there are only 11.3 in. The toilet stands beside it on the centreline, directly behind the chair, side-facing left with its back on the wet wall: 19.9 in from the chair back, 68.5 in over it collapsed, 144.5 in raised, and 26.8 in of knee room across the passage (22.8 in to the folded left seat). Its hood, two nesting leaves hinged along its back, is a backrest when open; closed, it seals on a gasketed floor tray, and a UV-C LED bar and a fan through a carbon filter to the roof vent run only while it is latched, so the toilet and tray can be sanitized and washed down to the shower sump. An accordion wall of 4 in panels, stacked 5 in deep at the wet wall’s front end, draws 49.3 in along the bed’s aft edge to the left door’s aft jamb and closes the toilet, the passage and the stair foot into one room; by day it stays stacked and the floor is open.

Deck, raised: about 107.5 in over the deck, seen from over the open double-height space ahead of the deck edge, with the rail along it. The couch is 80 in long, two seat cushions, about two thirds of the 117.6 in deck. The galley rises out of the floor to 36 in along the left wall and the table in front of the couch; lowered, each lid is a flush deck panel on a gasket. Under the front of the raised galley the fridge comes up too, its drawers facing the stairhead; on the road it waits low behind the bulkhead with its drawers to the low floor. At the front right the washer-dryer rises out of its well, its door facing forward over the deck edge at chest height for someone standing on the low floor; it needs the raised roof.

End views at the same scale, looking forward, at ride height.

How to read the end views

The first view cuts the front wheels at 0.65 m, where the footwell begins between the fresh-water tanks over the housings, with the crash stack ahead of it: the beam, the honeycomb block and the two tubes, the heat pump above. The low floor has 68.5 in at the centreline while driving and 144.5 in raised. The cockpit view shows the chair at its low setting with open floor on both sides, the right door with its gull-wing leaf beside it and, dotted, the crosswise twin over them, its mattress top 26 in up with 42.5 in over it at the centreline and 33 in at the walls, into the recesses in both door leaves. The third view, at 2.65 m, cuts the wet room ahead of the tridem: the shower at the right, off the centreline over a pan recessed 1.5 in into the floor, with 66.7 in at its centre (69.3 in at its inboard edge), a seated shower with the roof down, behind the fixed wet wall, with the right seat folded on its outer wall; the toilet on the centreline with its cover up as a backrest; and the stair extended along the solid left wall, 4 in off it where the left seat folds, with the grab bar at its foot. The fourth, at 3.10 m, cuts the deck front between the first tridem housings: the fridge, the gray tank and the washer-dryer under the deck and the folded stair on the landing above. The deck has 31.5 in while driving, with the couchbed lying flat as the bunk mattress and 25.5 in over it, and 107.5 in raised. Under the deck, 35 in of height between the housings holds the battery.

The cockpit at night with the roof down, looking forward: a made-up single bed lying crosswise from side wall to side wall over the folded seats, a man asleep on it under a grey blanket, the dark fan windscreen beyond, and in the foreground a white toilet on the centreline close to the bed’s edge, the shower’s closed white wall on the right and a grab bar on the left wall — **The crosswise twin:** parked, the chair drops 4 in and folds its back forward, the rear seats are folded flat on the walls, and four honeycomb leaves and a 4 in insulated air pad make a 36 × 78 in twin across the cockpit. Each end lies across a closed door on a bed bar between the jambs and tucks into a 1.7 in recess in the leaf; either leaf opens outward over the bed, 29.5 in clear above the mattress, so the two exits are at its two ends on opposite sides. 42.5 in over it at the centreline, 33 in at the walls. Behind it the toilet stands 8.7 in from its aft edge with the shower beside it, a 26.8 in passage runs along the left wall to the stair, and the accordion wall draws along the bed’s aft edge to close them off. By day the leaves and the folded pad lie in a 6.5 in rack under the roof over the chair, which leaves 62 in over the floor.

Looking aft from just behind the cockpit with the roof down: on the right of the picture a steep oak stair extended up to the high deck beside the solid left wall, a man standing at its foot holding a full-height grab bar; in the centre a white cassette toilet on the low floor in front of the oak deck front; on the left the shower’s white two-leaf wall folded back against its fixed wet wall; on the deck a flat made-up mattress under the low ceiling — **Stair and deck:** looking aft, so the stair, on the vehicle’s left, is on the right of the picture. A telescoping stair along the solid left wall, 19.5 in wide: four 9.25 in rises on 6.25 in goings, 56°, inside the 50–70° ship-stair range, its foot 2.2 in behind the twin beside a full-height grab bar on the left door’s aft jamb and its top on a 3.5 in nosing over the first left tridem housing, with a handrail on the flight and a rail along the deck edge. Its two sections telescope to 22 in and fold onto the deck’s front-left landing, 4 in thick, which frees the passage, the toilet’s knee room (3.3 in with the stair down, 26.8 in folded) and the fridge drawers. The left rear seat folds flat against the wall before the stair comes down.

The crawl bunk on the deck at night with the roof down, seen from the deck front: a woman reading on a made-up queen mattress lying on the oak deck under a low curved silver ceiling with dark rib arches, reading lights and a small escape hatch, a guard rail along the deck edge in the foreground and the oak stair folded upright against the left wall — **Crawl bunk:** with the roof down the couchbed lies flat on the deck as a 60 × 80 in mattress, 25.5 in under the ceiling at the centreline, and the pop-ups are sealed flush in the floor. The escape exit is a 28 × 22 in roof hatch over it; with the roof raised it is a 26 × 22 in window in the lowest band over the couchbed, which nests behind the fixed wall when the roof is down.

The deck at dusk with the roof raised, looking aft: the couchbed opened into a made-up 60 × 80 in bed along the right wall (on the left of the picture), a white washer-dryer risen at the near left ahead of its foot, the stairhead with its rail at the near right, one small window high in each side wall with redwoods outside, and a solid tail wall — **Raised, at night:** looking aft, so the bed along the right wall is on the left of the picture. The couchbed opens sideways into a 60 × 80 in bed 18 in above the deck, about three quarters of the deck long, with 89.5 in over it; the galley and table stay down in bed mode.

02 / Park and rise

Drive it low.
Raise it at camp.

Parked, four telescoping corner legs take the weight, the eight wheels draw up inside and curved panels close the arches. Then four synchronized corner masts lift the roof cap 76 inches on three nested wall bands inside a smooth outer fairing. Mechanical locks carry the load at every stage.

Road84.5 in ride · 79.5 in kneeling Camp13′ · 155.5 in crown

Drawn to scale from the design study: the left side, in inches above the ground at the 9 in ride height. The low floor runs between the wheel housings, behind the tires in this view; the dashed line over the tridem is the deck, 49 in up. The left door is right behind the front wheel housing; the right door is directly opposite it in the far wall. Road mode shows the framed wall: the lower chord over the tires, the seam rail and the upper chord along the roof edge, with the door’s pane the only glass in the fixed wall (the door cuts the lower chord and the seam rail, drawn through it here). Each end sweeps forward from its chin to a tip at the crown; the windscreen panes fill the nose from the 48 in sill to the hub at the tip, the dashed lines near each end mark the cap’s straight edge at the chin depth, and the dashed line at the front wheel is the arch, open from the chin for the tire at full lock. Kneeling lowers everything 5 in. In camp mode the copper outline is the smooth outer fairing over the nested bands; the glazed end screen (blue) at the nose and the bands’ end panels at the tail complete the upper half of each end; the body stands on its legs with the belly at 4 in and the wheels are retracted; each risen band carries its own row of panes. Renders are illustrative; the drawing governs.

1Stand and retract
Park level with wind below the 10 m/s lifting limit. Four corner legs extend onto broad pads and take the load, each wheel draws up on its suspension arms, and curved closures slide shut over the arches.
2Release and lift
Road locks release in sequence. One geared drive turns four mechanically synchronized corner winches; every stage has an automatic anti-drop catch.
3Lock and brace
Shear keys lock each stage at full height. Tensioned X-braces stiffen the walls and roof. If power fails, the locks still hold the roof.

A concept, outside the budget

The legs and wheel closures carry the SKIF and Habitat wheel-closure idea (design note jacks and wheel closure) to the 50K. The mass budget holds only four stabilizers at 551 lb. Full-weight legs and their hard points on the lower chords, the wheel lift and closures at four axle stations all need their own engineering at 50,000 lb. The only screen so far is the wall itself. Raised on four corner legs, the lower chord reaches 64 of 75 MPa, and at each door, where the lower chord and the seam rail are both cut, the sill beam alone carries the bay: 165 of 250 MPa at each door. Both walls pass, so four corner legs are the stance; a pair at 2.20 m, in the aft jambs of both doors, would bring the sill beams to 35 MPa and the chord to 36. Legs, lift and closures are not sized or weighed yet.

03 / Frame

The backbone moved
into the walls.

Each side wall is a framed girder, the way a bus side is built. A lower chord of hollow electroformed iron box vertebrae, clamped together by steel strand, runs nose to tail just above the tires; an upper chord runs along the roof edge; posts at the rib rings join them, and solid panels close the lower walls everywhere except one door in each, right behind the front wheel housing. The rib rings hang from the walls, so nothing structural crosses the floor.

The bare frame of the MSEC 50K: iron rib rings and posts framing each side like a bus, ribs radiating down from a hub at the crown of the nose and of the tail, behind the nose ribs a curved bumper beam with honeycomb and crash tubes, a water saddle tank over the front wheel and a small heat-pump unit, a door portal right behind the single front axle, a low cockpit floor and a raised deck frame over the three rear axles — The frame without its skin. Each rib ring is the full body cross-section, about 7 ft wide and 7 ft ½ in tall. In each side wall the lower chord runs nose to tail at 50–57 in, just above the tires, with a seam rail at the top of the fixed wall and an upper chord along the roof edge; posts at every rib ring frame the solid panels and one door portal in each wall, right behind the front housing. The floor tub hangs low between the front housings and the tridem; the deck frame spans the tridem 37 in above it.

Section through the middle tridem axle, drawn to scale at ride height. The lower chords sit about 6 ft apart over the tires and the upper chords along the roof edge, so nothing structural crosses the cabin. Between the wheel housings, from the low floor to the underside of the deck, 35 in of height and 55 in of width hold the battery. The deck spans the full width 49 in above the ground, 31.5 in under the ceiling while driving; the couchbed lies flat on it as the bunk mattress (dotted), 25.5 in under the ceiling at the centreline.

Box vertebra

The lower chord of each wall: 150 × 180 mm with 12 mm walls, 500 mm long, post-tensioned by steel strand. A bought steel box is the fallback if the thick iron does not qualify.

A rear wheel station: the chord overhead in the outer wall, an iron housing frame arching around the tire, double wishbones and a coil-over on the frame, a portal wheel-end with an electric motor on its input, and the low cabin floor beside it

Housing frames

Deep iron frames drop from each lower chord around the tires and carry the wishbones and dampers. Together with the rib rings and the floor tub they have to close the body into a torsion box.

Sized as a framed wall

Driving, shear keys at every post lock the roof cap down, so the lower and upper chords work together about 26 in apart. Each wall carries half of 50,000 lb on spring supports at the four axles, at 2.5 times weight, with a light and an even nose: worst case 100.9 kN·m and 92.3 kN of shear. Taking no credit for the solid panels, the iron lower chord reaches 52 of its 75 MPa limit and the steel upper chord 91 of 250; with the panels working as shear webs, 21 and 34. Each wall has one door, 28 in, and the two are opposite each other at 1.44–2.15 m, right behind the front wheel housings, where the hood loads come in. Each cuts the lower chord and the seam rail, and a portal of a 300 × 150 × 12 mm sill beam, two 0.10 m box jambs and the upper chord carries the bay: 72.7 kN·m and 62.6 kN in each wall, sill 35, over the door 41 and jambs 74 of 250 MPa. Parked on the four corner legs the sill beam carries each bay alone at 165 of 250 MPa, with the lower chord at 64 of 75, so both walls can take their door; a leg pair in the aft jambs at 2.20 m would bring the sills to 35.

A hood that crushes

The first 0.64 m of the nose, behind its rounded skin, is a staged crush stack: a 100 × 150 × 6 mm steel bumper beam 1.4 m wide at 16–22 in, a car’s bumper height, curved in plan to follow the skin, its face 0.17 m behind the nose tip; 0.13 m of aluminium honeycomb that crushes first at about 2.3 MN (10 g); then two 250 mm square steel crash tubes with 16.8 mm walls, 7 in either side of the centreline, crushing 0.26 m at about 6.8 MN (31 g). About 268 lb in all. Behind it the lower-chord segments ahead of the cockpit are made to fold, and the heavy modules under the deck sit on load-limiting mounts behind a bulkhead. As a sizing estimate only, not a crash simulation: stopping 50,000 lb from 30 mph against a rigid barrier is 2.04 MJ, which this stack absorbs in 0.39 m, 23.8 g on average against 20.4 g in the 0.45 m of the flat-nosed design; the rounded nose sets the beam back and costs that crush length. Behind that pulse, mounts that hold the 3,636 kg pack to 15 g need about 0.27 m of stroke, more room than the inverters and pop-up wells ahead of the pack leave today. The captain’s chair rides on a hexapod of six stroking struts over its air-ride stage, after crashworthy helicopter seats, which limit the load to about 14.5 g times the occupant and seat mass: sized for 15 g (about 20 kN) frontal over 0.15 m of seat travel, 92 mm of strut stroke, it holds that limit up to about 24 mph into a rigid barrier; at 30 mph it needs 0.27 m or a 19.3 g limit. Vertically it allows 14.5 g over 0.15 m, sideways 10 g over ±0.10 m, and its end stops take the FMVSS 207/210 seat and belt loads, about 34 kN. Posts, joints, shear keys, twist, suspension hard points and side loads are not checked.

The first 0.53 m of the nose is a staged crush stack: a 100 × 150 × 6 mm steel bumper beam 1.6 m wide at 16–22 in, a car’s bumper height; 0.15 m of aluminium honeycomb that crushes first at about 1.9 MN (9 g); then four 200 mm square steel crash tubes with 10.6 mm walls, 8 and 26 in either side of the centreline, crushing 0.30 m at about 5.8 MN (26 g). About 312 lb in all. Behind it the lower-chord segments ahead of the cockpit are made to fold, and the heavy modules under the deck sit on load-limiting mounts behind a bulkhead. As a sizing estimate only, not a crash simulation: stopping 50,000 lb from 30 mph against a rigid barrier is 2.04 MJ, which this stack absorbs in 0.45 m; behind that pulse, mounts that hold the 2,848 kg pack to 15 g need about 0.22 m of stroke, more room than the inverters and pop-up wells ahead of the pack leave today. The captain’s chair rides on a hexapod of six stroking struts over its air-ride stage, after crashworthy helicopter seats, which limit the load to about 14.5 g times the occupant and seat mass: sized for 15 g (about 20 kN) frontal over 0.15 m of seat travel, 92 mm of strut stroke, it holds that limit up to about 25 mph into a rigid barrier; at 30 mph it needs 0.22 m or a 17.5 g limit. Vertically it allows 14.5 g over 0.15 m, sideways 10 g over ±0.10 m, and its end stops take the FMVSS 207/210 seat and belt loads, about 34 kN. Posts, joints, shear keys, twist, suspension hard points and side loads are not checked.

The nose and the front wheel housings either side of the footwell are packed with light and dense things: the crash structure with the heat pump’s outdoor unit over it, the front axle’s housings and steering, 53 of the 70 gal of fresh water in saddle tanks over the housings whose tops follow the driver’s sightline (the other 17 gal lie in a flat tank under the deck front), the pump and filters and the 12 V electronics in the dash. Full, the steered axle carries about 12,180 lb, 26.1% of the weight and 69% of its tires’ rating; with both fresh tanks empty, 25.5%. The tridem tires run at 77%.

04 / Running gear

Eight wheels.
Four driven through portals.

One steered axle right behind the nose and a tridem of three axles at the back, 1.025 m apart, set 0.09 m forward so the last one clears the undercut tail. The front axle steers and the last tridem axle counter-steers to tighten the turn. The rear four wheels are driven by four electric motors through portal gear cases, so no shafts cross the floor.

The rolling chassis without a body: two iron side beams, a curved bumper beam with honeycomb and crash tubes at the front, one steered front axle, a long low floor, and a tridem of three axles at the back with battery modules between them and a propane tank and generator at the tail — Rolling chassis concept: the two lower chords, the crash structure, one steered axle, the low floor, the tridem with the battery between its housings and the propane gear at the tail. The upper chords and posts come with the rib rings.

Tires: Front 355/50R22.5 156L, 36.5 in, 8,820 lb each; tridem 295/60R22.5 150/147L, 36.4 in, 7,390 lb each
Track: 1.737 m at the front, 1.798 m at the tridem; the outer tire faces stay 82.4 in apart
Axle stations: 0.825 m (steered) · 3.30 · 4.32 · 5.35 m (tridem, 1.025 m apart); 14.8 ft outer span, 51,900 lb on the federal bridge formula
Suspension: Independent wishbones; 150 mm bump and 150 mm droop reserved
Portal: Two spur gears, 2:1, 300 mm drop; bought hardened gears and bearings
Drive: 8×4: the front axle steers; the last tridem axle counter-steers 12° electronically; the rear four tridem wheels are driven by electric motors

Cutaway of a portal wheel-end: upper input gear driving a larger lower gear, wheel bearings, disc brake and a 42 inch tire

Choose how the portals are driven

MechanicalEarlier baseline ElectricSelected

The earlier baseline: a used ISB/B6.7-class diesel of about 300 hp, an Allison automatic, differentials and shafts to the portals. It needs a machinery block and shaft corridors that would cut into the clear aisle, so it was dropped for the low-aisle layout.

A ~400 kWh battery under the deck feeds four rear traction motors on the portal inputs; a 5.5 kW propane generator is a backup, not a range extender. About 127 kW holds 70 mph on level road; 55 mph up a 6% grade needs about 470 kW, so the motors and inverters have to be sized for that. Used motor-inverter assemblies are listed from $2,195 each, before reductions, cooling and controls.

05 / Ribs and skin

Polygon ribs.
A smooth skin.

Every half metre, a ring of twelve straight electroformed iron segments meets at keyed knuckle joints, the same joint language as the vertebrae. The rings hang from the framed side walls, a low floor tub closes their bottoms, and curved battens fill the corners so the skin is one smooth curve.

Cutaway of the body wall: an iron rib corner with a keyed joint, insulation and an oak lining inside, curved spacers under the smooth silver skin outside

Rib to skin

Insulation and an oak lining fill the inside of each rib. Outside, crescent spacers and curved battens carry the skin across the polygon’s corners, so no facet shows.

Masts, bands and locks

Four corner telescopic masts with three sections each, each with at least 10 kN of working lift after reeving losses. Mechanical catches stop each stage if a line fails. In camp mode, 8 kN X-braces in the walls and roof take the wind.

Where the weight lives

Battery under the deck Fresh water in the hood Propane tank and generator at the tail

The heavy items sit low: the battery between the tridem housings under the deck, the propane gear at the tail, 53 gal of fresh water in the hood. In a rough estimate the steered axle carries about 12,180 lb, 26.1% of the weight and 69% of its tires’ rating, and the tridem 34,410 lb, 78%; the water in the hood adds about 440 lb to the front axle. The CG sits about 31.7 in above the ground, roughly 3 in lower than the central-seat layout of 2 November. Moving walls carry only light panels.

06 / Inside, in detail

The sizes
that matter.

Driving, the low floor is 12 in off the ground at ride height and the ceiling 68.5 in above it at the centreline, so the cockpit, passage and toilet have standing room with a slight stoop; the deck is 37 in higher, a crawl bunk on the road and a 9 ft room raised. The widths are set by the wheels: the front axle steers inside its housings and the tridem housings bound the space under the deck.

Ceilings: Low floor: 68.5 in (5 ft 8½ in) at the centreline driving, 144.5 in raised. Deck: 31.5 in driving, 25.5 in over the flat couchbed; 107.5 in (8 ft 11½ in) raised, 89.5 in over the bed. Under the deck: 35 in
Cockpit: 75 in wall to wall from the end of the front housings at 1.34 m; the footwell runs forward between the front wheel housings to 0.64 m. The chair back is at 1.97 m. The captain’s chair sits low on the centreline: 68.5 in of headroom against the 58 in a 6 ft 3 in driver needs at the low setting (14 in cushion, 39 in sitting height, 2 in travel, 3 in clearance); a 5 ft 4 in driver uses the 20 in setting. 1.02 m from the pedals’ heel point to the seat back. Nothing stands beside the chair: the floor is open to both doors. No cockpit side windows: the doors’ panes, one each side beside the chair, are the side glass. Behind the chair by day, 19.9 in to the toilet front
Rear seats: Two forward-facing passenger seats, one on each side wall from 2.28 to 2.79 m, behind the wet room line and 12.1 in behind the chair back, their 4 in backrests on the faces of the first tridem housings: 18 in wide, the 16 in pan 18 in up, 37 in of legroom from the pan front to the front housings ahead and 63.9 in of headroom against 60 in. Folded, the pan flips up and the seat swings flat on its wall, 4 in thick, 15–42 in up. The right seat stands in the shower on a drained teak-slatted pan, so it is also the shower seat, and folded it leaves the shower 21.3 in wide below it and 25.3 in above; the left one is in the passage and, folded, clears the deployed stair. They compete for floor: the right seat folds before the shower wall can close, the left before the stair comes down or the toilet wall is drawn, and both for the twin; the stair and the walls cannot latch otherwise, and driving, an occupied seat needs its belt latched. Facing forward, they need three-point belts anchored to the frame, a harder frontal-crash case than the rear-facing seats they replace. About 60 lb each
Crosswise twin: Parked, with the roof down, the chair drops 4 in on its air stage and folds its back forward to 15 in, the rear seats are folded flat on the walls and the steering column tilts up. Four honeycomb platform leaves on ledges across the cockpit carry a 4 in insulated air pad: a 36 × 78 in twin from the end of the front housings at 1.34 m to 2.25 m, its sleeping surface 26 in up, for a 6 ft 3 in sleeper. 74.6 in lie between the lower walls. Each end lies across a closed door: a bed bar clips between the jambs at platform height and the mattress tucks into a 1.7 in recess in the lower leaf, with 1.9 in of foam left behind it (about R 11 against R 18 elsewhere) under its own sealed liner. Either leaf still opens outward over the bed, 29.5 in clear above the mattress at the wall plane and 38 in under the gull-wing leaf, by 28 in wide, which passes the escape ellipse; the two exits are at the twin’s two ends, on opposite sides. 42.5 in over the twin at the centreline, 33 in at the walls, 118.5 in raised and 8 in under the stowed wheel. One sleeper here; the second sleeps on the deck bunk. Behind it the toilet stands 8.7 in from its aft edge, with the shower beside it at the right; at the left a 26.8 in passage runs 21 in along the solid left wall to the deck front, and the accordion toilet wall draws across along the bed’s aft edge. The twin’s sleeper leaves by either door over the bed’s end, or steps off its aft edge at the left through the accordion wall into the passage for the toilet and the stair, or at the right straight into the shower. The deck sleeper unfolds the stair from the landing, its foot 2.2 in behind the bed, comes down and leaves by climbing onto the twin’s end, 26 in up, at either door. By day the four 19.5 × 36 × 1 in leaves and the pad, folded to 2 in, lie in a latched 6.5 in rack under the cap over the chair, 1.76–2.25 m; it leaves 62 in over the floor against the 58 in the driver needs, and 41.5 in over the made twin. The chair still reclines for lounging
View ahead: Glass only above about 48 in. The eye sits about 60.5 in above the ground for a 6 ft 3 in driver on the low setting and 59.1 in for a 5 ft 4 in driver on the high one, in the middle of the lower side pane (57.5–63.5 in, under the seam rail). The whole windscreen is in the fixed nose, so no mullion crosses the view. A signal head 17 ft up and 40 ft ahead needs a 16.6–16.8° up-angle; the glass top under the hub disc, 82 in up, allows 17.1° for the tall driver and 18.2° for the short one, margins of only 0.5° and 1.4°. The road is hidden for about 6.6 m (22 ft) ahead of the nose, 7.5 m for the shorter driver, so a front camera is recommended. The dash and the hood top have to stay under 57.4 in at the end of the hood
Windscreen: One fan of tapered panes in the fixed nose, from the 48 in sill up to a 5 in hub disc at the nose tip, 84.5 in up on the centreline, where the nose meets the roof; the sill is 0.04 m behind the tip. The panes stay put when the roof rises. Raised, a folding glazed end screen hung from the cap’s front edge unfolds over the upper half of the nose, from the hub to the cap, so the raised profile is symmetric about the tip; roof down, it folds into a 6 in cassette under the cap at 0.90–1.70 m, whose underside, 74.5 in up, stays above both drivers’ sightlines to the glass top (71.1 and 70.4 in there). The screen’s hinges, guides, drive and seals are a concept, not a design
Doors: One in each side wall, directly opposite each other, both 28 in wide from 1.44 to 2.15 m, each front jamb, a 0.10 m steel box, against the end of its front wheel housing, beside the chair. Right: the main entrance and opens onto a 32 × 25 in vestibule beside the chair, with the shower right behind it. From the vestibule to the passage the way is across the shower pan with its wall folded back and the right seat folded, 23.3 in wide; behind the chair there are only 11.3 in. Left: straight onto the passage, 34.3 in along the left wall to the stair foot; it relieves the 11.3 in behind the chair. From the door to the tail the left wall is solid; a full-height grab bar on the door’s aft jamb serves the door and the stair foot. At night both doors open over the twin’s ends. Sills at 12 in. Collapsed, the lower leaf in the fixed wall clears 55.5 in at the wall plane and a gull-wing leaf in the cap opens above it for 64 in of height 10 in inboard. Raised, the bands are cut through over each door for 72 in clear; above the door the gap is closed by flush insulated tambours in the body colour, which run on tracks in the band edges and roll up into the cap before the roof lowers, so the raised side shows smooth panels over the door
Wet room: Right behind the right door, entered from the cabin (the vestibule and the passage), the shower is also the mudroom: 24.4 × 25.3 in on a teak grate over a pan recessed 1.5 in into the floor stack, 4.1 in behind the door’s aft jamb, closed by two rigid gasketed 12.65 in leaves hinged on the fixed wet wall along its inboard edge, which stack 2 in thick against that wall when open and leave a 23.3 in opening, and a sump pump to the gray tank. Off the centreline, it has 66.7 in at its centre and 69.3 in at its inboard edge with the roof down, a seated shower, and 142.7 in raised; the first right tridem housing stands in its aft outboard corner as a 3.5 × 9.9 in bench, 33.4 in above the pan. Beside it, in the same band from 2.48 to 2.88 m, the cassette toilet stands on the centreline directly behind the chair, side-facing left with its back on the wet wall, 15.7 × 19 in, with 68.5 in over it collapsed and 144.5 in raised and 26.8 in of knee room across the passage to the left wall (21 in needed; 22.8 in to the folded left seat). Its hood, two nesting leaves hinged along its back, makes a 3 in backrest open; closed, it seals on the gasketed rim of a floor tray, and a UV-C LED bar in the hood and a 12 V fan through a carbon filter to the roof vent run only while it is latched; the tray and the bowl wash down to the shower sump. An accordion wall of 4 in panels, stacked 5 in deep at the wet wall’s front end, draws 49.3 in along the twin’s aft edge to the left door’s aft jamb and closes the toilet, the passage and the stair foot into one room; it needs the left seat folded. By day both walls stay open and the floor is one room. The 18 gal gray tank stands under the front of the deck right behind the toilet, between the fridge shaft and the washer-dryer well, 21.7 × 13.2 × 19.5 in; the space costs about 21 kWh of battery
Stair: On the left, extending. The shower holds the right side behind the right door and the toilet the centre, so the passage along the left wall is the only free floor, and the left door opens straight onto it; a fixed flight would take that passage for good. Deployed, the flight runs along the solid left wall, 19.5 in wide: four 9.25 in rises on 6.25 in goings, 56°, inside the 50–70° ship-stair range, from a foot 2.2 in behind the twin, beside the full-height grab bar on the left door’s aft jamb, to a 3.5 in nosing on the deck over the first left tridem housing, with a handrail on its inboard stringer that folds with it. 37.7 in over the top tread collapsed (a crawl onto the bunk) and 113.7 in raised. Its two sections telescope to 22 in and fold on a deck-lip hinge with gas struts onto the deck’s front-left landing, 4 in thick, which frees the passage, the toilet’s knee room (3.3 in with the stair deployed, 26.8 in folded) and the fridge drawers. It cannot unfold until the left rear seat is folded; folded, that seat lies between the stair and the wall, so the flight stands 4 in off the wall. About 65 lb with the rails
Deck: 117.6 in long, from 2.88 m to the tail, with a 3.5 in nosing at the left over the first tridem housing for the stair top; 74.6 in between the lower walls and 69.2 in between the lower chords for the first 8 in above it. No cabinets and no bed overhead: only the couchbed lies on it, and everything else rises out of sealed wells. The first 37.6 in ahead of the couchbed’s foot is clear of the flat bunk; it holds the stair landing (22 × 23.5 in) at the left and the washer-dryer’s hatch at the right, 17.1 in apart. 39–42 in clear beside the couch in couch mode, 9–12 in beside the bed in bed mode, so the bed is reached from its foot
Couchbed: SKIF-style, along the right wall at the back, 80 in long. Flat for the road, a 6 in stack on the deck that is the bunk mattress, with 25.5 in over it at the centreline and 22 in at 10 in from the wall. Raised, a couch with an 18 in seat 22 in deep and its back at 38 in; at night the seat slides out sideways and a trundle comes up to make a 60 × 80 in bed at 18 in. Four-bar lift links fold into 1.5 in deck pockets; it stays on the deck because a pocket under it would cost about 0.5 m³ of battery space; about 140 lb
Pop-ups: The galley, fridge, washer-dryer and table each rise from a well under the deck on electric columns, flush when down on an EPDM bulb seal over a drained gutter. Galley: 39.5 × 21 in along the left wall behind the stair landing, 3.44–4.44 m, flush in a pocket when down with its bowl 5 in deep inboard of the housing at the aft end; two three-stage columns behind the fridge lift it to 36 in and its front 22.5 in is carried over the fridge by the wall guide; about 80 lb. Fridge: 3 cu ft double drawer (16 × 22 × 33 in), 120 lb with its slide and lift. On the road it sits low behind the bulkhead with its drawers to the low floor; raised, it slides 22.5 in aft under the galley’s front bay and rises 37 in on twin ball-screw columns to stand under the slab with 0.5 in to spare, its drawers facing the 22 in landing, so it never stands on the stair top; the raised slab is its lid, with a 3 in flap inboard. Table: 28 × 18 in to 26 in on a two-stage pedestal from a 1.25 in pocket, 4.97–5.68 m. The galley and table stand inside the flat bunk’s footprint, so they rise with the couchbed in couch mode, and the fridge only with the galley up. Washer-dryer: a ventless condensing combo, 23.5 W × 21.25 D × 33.5 H in, 150 lb plus 60 lb of lift, in a sealed well at the front right, 2.88–3.43 m, with 15.8 in to spare ahead of the couchbed’s foot. Twin telescoping columns raise it 37 in from the low floor to stand on the deck, its door facing forward over the deck edge and the shower with its centre 53.5 in above the low floor, loaded standing in the shower with its wall folded back or kneeling on the deck; down, its lid is a flush deck panel. It needs 35.5 in over the deck, so it rises only with the roof raised, in any couchbed mode. A cycle takes about 13 gal of the 70 gal of fresh water and 2 kW; it drains 1.7 m to the 18 gal gray tank beside its well and is fed 4.3 m from the hood, both with 1.2 m loops for the stroke, and its condensate shares the drain, with an air-admittance valve under the deck. The well costs about 0.30 m³ of battery space
Roof interlock: The cap cannot lower unless the couchbed is flat, the galley and table are down with their lids sealed flush and the hob lid shut, the twin is stowed, and the door-gap tambours are rolled up into the cap. Traction stays off while either door is unlatched, a bed bar is clipped across either doorway or the leaf rack is unlatched; the rack is rated for the nose crash pulse. Position switches on each feed the lift and drive controllers
Egress: NFPA 1192, as quoted in secondary sources, asks for two remote exits and an escape opening that passes a 24 × 17 in ellipse. The doors are both 28 in wide, on opposite sides at the twin’s two ends; each opens over the bed with 29.5 in above the mattress, which passes the ellipse. From the passage or the deck the way out at night is onto the twin’s end, 26 in up, at either door. Collapsed, the lowest band nests behind the fixed wall, so the bunk’s second exit is a 28 × 22 in roof hatch between doubled ribs over it; raised, a 26 × 22 in window in that band on the right over the couchbed, its sill 69 in up and 20 in over the deck. The tail is solid

07 / Power and stores

One big battery.
Electric wheels.

About 400 kWh of LFP fills the space under the deck between the tridem housings, with the power electronics at its front and the propane gear at the tail. It drives the four rear motors, takes back braking energy on the way down and runs the house. It charges at truck DC fast chargers, on AC hookups and a little from roof solar; parked, a small boxed-in propane generator runs the house and can top the pack up.

Cutaway of the rear of the MSEC 50K: stacked battery modules with orange cables and blue cooling lines between the three rear wheels under the deck, a two-drawer stainless fridge, a white gray-water tank and a front-loading washer-dryer side by side at its front, and a propane tank and a generator in a lined box lying one behind the other at the same low level at the tail behind an open service hatch hinged at its bottom edge; the left wall at the edge of the cutaway is solid, with no door — Under the deck: 3.52 m³ between the tridem housings, 35 in tall, behind a sealed, fire-rated bulkhead at 2.88 m. The battery sits on load-limiting mounts. The fridge’s shaft (0.43 m³, its low position and the slide to its raised one), the washer-dryer’s well at the front right (0.30 m³), the 18 gal gray tank between them (0.09 m³), a flat 17 gal fresh tank behind them (0.07 m³), the inverters and the generator’s acoustic enclosure take their share, so about 400 kWh fits, filling the rest. Along the sides the tridem tires leave only 4 in between them, so the compartments open through a tail hatch, not side hatches.

Battery: About 400 kWh LFP for traction and the house, about 8,016 lb at 110 Wh/kg, under the deck beside the fridge shaft, the washer-dryer well, the gray and fresh tanks and the pop-up wells; the longer deck makes room for the 400 kWh target (402 would fit)
Range: About 210 / 188 / 177 miles at 55 / 65 / 70 mph on 80% of the pack, at 1.5–1.8 kWh per mile
Grades: 70 mph needs about 127 kW on level road; 55 mph up a 6% grade needs about 470 kW, 1.2 C; climbing 1,000 m costs about 72 kWh before regeneration
Charging: 10–80% in about 1.9 h at a 150 kW average, 1.1 h at 250 kW, 0.8 h at 350 kW; about 14.6 h on 19.2 kW AC; roof solar about 7 kWh on a sunny day
Hood: 53 gal of fresh water in saddle tanks over the front housings, 0.22 m³, whose tops follow the driver’s sightline (49.3 in at the front, 56 in at the back), and 17 gal more in a flat tank under the deck front; the water pump, filters and UV in the dash over the footwell; the 12 V electronics; and the heat pump’s outdoor unit and the pack chiller in the nose over the crash stack behind a grille, sacrificial in a crash like a car’s radiator. The 18 gal gray tank is under the deck front · cassette toilet
Generator: Parked use only: house loads and topping up the pack, never while driving. An Onan QG 5500 LP-class generator, 5.5 kW and 288 lb, and a 16 × 61 in ASME tank, about 40 gal usable and an estimated 353 lb full, side by side at the tail under the deck. A fill makes about 199 kWh, over 36 hours at full load; a 10 h run burns 11 gal and puts about 50 kWh, 12% of the pack, back in. Propane also feeds a room-sealed furnace and water heater; the cooktop stays induction
Quieting: Box in box: the vapour-tight 26-gauge galvanized liner NFPA 1192 asks for, and inside it a decoupled acoustic hood of steel, 50 mm mineral wool and a mass-loaded barrier, 2.5 in a face, 40.6 × 29.2 × 23.7 in outside. Cooling air in through a lined labyrinth in the belly and out through a splitter silencer. Two isolation stages, the genset’s own mounts (about 12 Hz) on a subframe on elastomer mounts (8 Hz, 3.9 mm static deflection), well below the 60 Hz firing frequency. Targets: the bare installed set is about 69 dB(A) at 10 ft, 62 at 7 m and 55 at 50 ft, already under the National Park Service’s 60 dB(A) at 50 ft; the target is 50 dB(A) at 7 m (43 at 50 ft), about 12 dB of insertion loss, and inside 35 dB(A) at the cockpit bed and 40 at the deck bunk over the compartment. These are targets, not predictions
Exhaust: The Onan muffler with its USDA spark arrester and a secondary silencer; the tailpipe leaves the undercut tail left of the centre, 12 in up and 2.2 in past the skin there, inside the body length, pointing aft and outward, below the service hatch and behind the last left tire. Nearest openings: the generator’s own air intake 39.5 in away, the LP fill and relief 41 in, the raised window over the galley 70 in, the left door about 12 ft and the right door about 13 ft; at least 36 in to every door, window, hatch, LP fitting and intake, and 55.5 in below the cap’s seam. CO alarms at the cockpit bed and the deck bunk and an LP detector low in the cockpit
Interlock: The generator will not start or run unless the park brake is set and the traction contactors are open, the roof is still, the roof escape hatch, tail hatch and compartment doors are shut, and no CO or LP alarm is sounding; an alarm stops it
Compartments: Per NFPA 1192 as summarized in secondary sources: the LP compartment is vapor-tight to the cabin, opens and vents only to the outside, with vents at its top and bottom; the generator compartment is lined with 26-gauge galvanized steel with lapped seams; the exhaust ends past the body edge, away from openings, never under the vehicle, supported every 4 ft. Onan builds the set to ANSI/RVIA EGS-1 and NFPA 1192
Certification: Retailers list the QG 5500 LP as EPA and CARB compliant as a small nonroad engine. EPA’s heavy-duty rule (40 CFR 1036.5) counts a generator engine that charges a propulsion battery as indirectly propelling the vehicle, which would make it a motor-vehicle engine needing on-road certification. Charging only while parked does not obviously change that, so the pack-charging connection waits for an answer from EPA; the house loads do not

Every pound has a place

Budgeted, not weighed: 46,589 lb allocated with everything aboard, the water and propane tanks full and a 2,205 lb growth allowance, leaving 3,411 lb of the 50,000 lb ceiling unallocated.

Mass allocation by item, pounds
Item	Pounds
Wheel ends, tires, brakes, portals	8,818
Traction and house LFP, ~400 kWh	8,017
Ribs, floor, shells, roof and lift	5,050
Framed side walls: chords, seam rails, posts, tendons	4,200
People, food, tools, spares, cargo	3,527
Suspension, steering and rear steer (no shaft credit taken)	3,367
Interior, insulation, HVAC, plumbing	3,086
Construction-growth allowance	2,205
Protection and RF package	1,808
High deck, bulkhead, crash structure, nose end screen, two doors, crash mounts	1,450
Propane generator in its acoustic enclosure, tank full, furnace, compartments	816
Water, all 88 gal full	734
Four rear traction motors and inverters	690
Inverters, chargers, wiring	661
Empty tanks and restraints	551
Four stabilizers	551
Deck: couchbed, galley, fridge, washer-dryer lift, table	423
Cockpit: hexapod chair, crosswise twin, rear seats, wet room, stair, grab bar	335
DC fast-charge inlet, HV junction, pack cooling	300

08 / How it’s built

From bath to road
in eight steps.

The bulk structure is electroformed in-house. Strand, anchors, bearings, gears, brakes, battery modules, motors and the electrical gear are bought.

1Grow the parts
Box vertebrae, end plates, housing frames and ribs are electroformed in iron on reusable mandrels.
2Stack the lower chords
Twelve box vertebrae per side line up on a roller jig with their keyed faces meshed; steel strand is threaded through the ducts.
3Tension the strand
A multi-strand jack draws each chord’s strand to its preload, and wedge anchors lock the ends.
4Make it roll
Housing frames, wishbones, coil-overs, portal wheel-ends, motors, steering and brakes hang from the two lower chords: one steered axle at the front and the tridem at the back.
5Raise the ribcage
Twelve-sided rib rings with keyed corner joints bolt to both lower chords and close the low floor tub; seam rails, posts and the upper chords turn each side into a framed wall, and the deck frame spans the tridem.
6Install the systems
The battery, power electronics and the sealed wells for the fridge, the washer-dryer and the pop-up galley go in under the deck between the tridem housings, the propane tank and the generator in its acoustic enclosure into sealed compartments at the tail, the fresh water into saddle tanks over the front axle and a flat tank under the deck front, and the heat pump into the nose.
7Close the skin
Nested wall bands, corner masts and curved battens go on, the smooth skin closes over the ribs, a door goes into each side right behind the front wheel housing, and the fan windscreen goes into the rounded fixed nose, above the crash stack and under the hub at its tip.
8Prove it
Weigh every corner, test brakes and steering, cycle the roof and the wheel lift, and qualify the structure before any road use.

09 / Specifications

The numbers.

DimensionsChassisBodyPower and stores

Body length: 6.0 m (about 19 ft 8 in); the bumper beam is inside the nose, so lights and fittings share the remaining 96 mm to 20 ft; both ends blend smoothly around a broad centre at the roof line, and the tailpipe tip stays inside the length
Width, collapsed: 83 in nominal fairing; 84 in hard maximum including stowed hardware
Height, driving: 84.5 in crown at the 9 in ride height; kneels 5 in to a 79.5 in crown at walking pace for an 80 in limit
Height, raised: 155.5 in crown; 156 in (13 ft) hard maximum
Optional parked width: 102 in (8.5 ft) with side pods; not shown in the current renders
Floor / clear height: 12 in low floor and 9 in ground clearance at ride, 7 in and 4 in kneeling; 68.5 in clear collapsed, 144.5 in raised over the low floor; deck at 49 in, 31.5 in clear collapsed, 107.5 in raised; approach angle about 29° at ride and 12° kneeling, departure about 66° and 20°
Zones: Front wheels and crush zone 0–1.34 m, with the footwell running forward between the front wheel housings to 0.64 m; cockpit and its twin 1.34–2.25 m, with both doors at 1.44–2.15 m; shower, toilet, passage and stair 2.25–2.88 m on the low floor; deck 2.88 m to the tail
Axle group: 1 steered axle at 0.825 m and a tridem at 3.30 / 4.32 / 5.35 m, 40.4 in apart; 14.8 ft outer span, 51,900 lb on the federal bridge formula; tridem 41,000 lb

Side walls: Framed like a bus side: a post-tensioned lower chord of electroformed iron box vertebrae, 150 × 180 × 12 mm, at 50–57 in; a 100 × 100 × 6 mm steel seam rail; a 300 × 150 × 12 mm steel sill beam under each door; a 150 × 150 × 8 mm steel upper chord along the roof edge; posts at every rib ring, 0.5 m apart; solid lower walls; one door portal in each wall, opposite each other at 1.44–2.15 m, right behind the front housings
Bending check: 100.9 kN·m and 92.3 kN worst case per wall driving: lower chord 52 of 75 MPa, upper chord 91 of 250 MPa with no credit for the solid panels (21 and 34 MPa with them as shear webs); each door portal 72.7 kN·m: sill 35, over the door 41, jambs 74 of 250 MPa. Raised on four corner legs, 64 of 75 MPa with each sill beam alone at 165 of 250; with a leg pair at 2.20 m, 36 of 75 and 35 of 250; posts, joints and torsion not yet checked
Wheel loads: Rough: about 6,091 lb per front tire (69% of rating) and 5,735 lb per tridem tire (78%); 26.1% of the weight on the steered axle (25.5% with both fresh tanks empty), with the tridem load-equalized and the unplaced mass spread evenly
Wheels: 8 single tires: 355/50R22.5 on the front axle, 295/60R22.5 on the tridem
Steering / drive: Front axle steers, 35° inner lock; last tridem axle counter-steers 12°; the rear four tridem wheels are driven by electric portal motors (8×4); turning circle about 46.6 ft curb to curb (50.8 ft without the rear steer, which costs about 39 kWh of space under the deck; 10.8° on the last axle gives 47 ft)
Portals: 2:1 spur pair, 300 mm offset, bought gears and bearings

Rib rings: Twelve-sided electroformed iron rings at 0.5 m pitch with keyed corner joints; closed 220 × 100 × 6 mm floor ribs
Skin and glazing: Smooth curved skin on battens over the rings; each end a shallow, smoothly rounded cap, 0.30 m deep, sweeping forward from a set-back chin to a broad centre at the 84.5 in crown, and raised completed by its upper half so the profile is symmetric about the tip; solid lower walls, glazed only in the two doors, right behind the front wheels; raised, 15 panes a side in three rows of five, each row inside its own band, 42.0% of the risen side glazed, with solid frames and an opaque door column; the lower right pane at 4.10–4.76 m is the escape window; the windscreen is one fan of tapered panes in the fixed nose from the 48 in sill to a hub disc at the tip, over the crash stack, with a folding glazed end screen over the upper half when raised; a solid tail; the front wheel arches open from the chin, and the last arches are cut back into the tail corners
Doors and exits: One 28 in side door in each wall, opposite each other right behind the front wheel housings, 12 in sills, 55.5 in clear at the wall plane collapsed (64 in under the gull-wing leaf) and 72 in raised: the right one the main entrance onto a vestibule with the shower behind it; the left one straight onto the passage; at night both open over the ends of the crosswise twin. The tail is solid with a service hatch below the deck, the generator tailpipe below it and no window. Driving, the exits are the two side doors and, from the bunk, a 28 × 22 in roof hatch; raised, the side doors and the 26 × 22 in window in the lowest band on the right, its sill 20 in over the deck, with a fold-down ladder outside. All pass the 24 × 17 in NFPA 1192 ellipse
Floor: Low tub hung from the rib rings from the front housings to the deck at 2.88 m, with the shower pan recessed 1.5 in into it; a deck of frames and honeycomb panels over the tridem with a sealed bulkhead at its front and sealed wells for the pop-ups and the washer-dryer
Captain’s chair: Air ride stage with 0.10 m of travel under a hexapod of six stroking struts, belts built into the seat; a sizing estimate for a 15 g frontal limit (about 20 kN) over 0.15 m of seat travel, 92 mm of strut stroke, 14.5 g vertical over 0.15 m and 10 g lateral over ±0.10 m. It reclines and drops 4 in on its air stage under the crosswise twin, parked only
Roof: Curved cap, 17 in rise, with a straight front and back edge at the chin depth; three 38 in bands, 25.33 in stroke, 12.67 in overlap, with rigid end panels that form the upper half of the tail; at the nose a folding glazed end screen
Lift: Four corner masts, mechanical synchronization, anti-drop catches, lift below 10 m/s wind
Bracing: Tensioned X-braces, 8 kN working load per active diagonal
Protection: 820 kg protection and RF package allocated

Top speed: 70 mph target; about 127 kW at Cd 0.65 × 4.0 m²
Engine: No traction engine; a 5.5 kW propane generator in an acoustic enclosure, parked only, for the house loads; charging the pack from it waits on an EPA certification answer
Traction: Four rear motor-inverters on the portal inputs, to be sized for about 470 kW on grades; no differentials or long shafts
Battery: About 400 kWh LFP under the deck, traction and house; 210 / 188 / 177 mi at 55 / 65 / 70 mph
Charging: DC fast-charge inlet for 150–350 kW truck chargers; 19.2 kW AC; about 8 m² of roof solar
Water: 70 gal fresh, 53 in saddle tanks over the front housings and 17 in a flat tank under the deck front, 18 gal gray under the deck front behind the toilet; cassette toilet, no black tank; propane tank about 40 gal usable at the tail

Status

A concept,
stated plainly.

These are design allocations and analytical screens, not a rated, registered or tested vehicle. Nothing is inherited from a donor truck.

Fit gates. Motor, inverter and pack cooling sizing for ~470 kW climbs; the 690 lb motor allowance is unchecked against that. Wheel, steering, CV and brake sweeps against the housings and floor tub.
Framed walls. Posts, joints, the shear keys between cap and wall, post buckling, twist with the rings and floor tub, suspension hard points and side loads are unchecked. Each door portal is screened as one Vierendeel panel, both now in the bays right behind the front housings where the hood loads come in; parked, where each door cuts both the lower chord and the seam rail, the sill beam carries the bay alone at 165 of 250 MPa on four legs; a leg pair at 2.20 m would bring it to 35. The axle loads are rough statics with the tridem load-equalized; the wall bending screen still assumes an even load.
Materials. Thick electroformed iron, its joints and fatigue life are still unqualified.
Mechanisms. Mast reeving, catches and locks; rib buckling and connections.
Skin and retraction. One smooth skin across 76 in of roof travel, the full-weight legs, wheel lift, housings and arch closures are styling targets without a mechanism design. Raising assumes the wheels are retracted first.
Crash. The rounded nose sets the bumper beam back, so the crush stack is 0.39 m (23.8 g average at 30 mph, against 20.4 g for 0.45 m), sized by a rigid-barrier energy estimate, not a crash simulation; the honeycomb, the tubes, the fuse segments in the lower chord and the bulkhead are not designed, and the pack’s 0.27 m mount stroke needs room the inverters and the pop-up wells occupy today. The captain’s chair hexapod is a sizing estimate too: 0.15 m of seat travel holds 15 g only up to about 24 mph into a rigid barrier; the 30 mph pulse needs 0.27 m or a 19.3 g limit. The rear seats have no stroke and face forward on seat-mounted three-point belts, the frame anchored to the lower chord and the tridem housing face, so a frontal pulse goes into the belts rather than a backrest: a step down from the earlier rear-facing seats, in exchange for 37 in of legroom and a clear view past the driver. The driver sits just behind the front axle, so the ride over it will be firm.
Pressure hull. The integrated pressure-cabin goal is retained but not designed: today’s body is an ambient-pressure weather body.
Road use. No crash test, axle, tire or registration rating exists yet. The 70 mph power and the range figures assume a Cd of 0.65; fast charging needs truck-sized DC chargers.
Ends, windows and bands. The windscreen is all in the fixed nose, so no pane crosses the moving joint, but its glass top under the hub leaves only 0.5° over the signal-head sightline for a 6 ft 3 in driver. Rigid band slices cannot nest inside the rounded ends: lowered, the nose slices would stand up to 2 in proud and lie behind the windscreen, so the nose uses a folding glazed end screen in a ceiling cassette, and at the tail the bands’ end panels are set back, which leaves steps of up to 2 in at their lower edges when raised. The screen’s kinematics, the cassette, the tail panels, the raised rows and the nested panes’ seals are concepts, not designs. The road is hidden for about 6.6 m ahead of the nose, so a front camera is recommended.
Pop-ups, bed and doors. The couchbed’s lift links, the galley, fridge, washer-dryer and table columns and the fridge’s slide, their lid seals and hose loops, the crosswise twin’s leaves, air pad, the two bed bars and the recesses in both door leaves, the leaf rack over the chair and its crash retention, the chair’s drop and fold and the stowing column, the doors’ gull-wing leaves, the band cut-through over each door and its tambours, the shower wall and its gaskets, the toilet hood, its UV-C cycle and the accordion wall are concepts, not designs. The galley and table rise only in couch mode, the fridge only under the raised galley and the washer-dryer only with the roof raised; one washer cycle (13 gal) takes most of the 18 gal gray tank, so the gray tank must be emptied before a second load. The bunk’s escape is up through a roof hatch about 7 ft above the ground, which needs handholds or a ladder outside. The NFPA 1192 figures come from secondary sources, not the standard itself.
Layout. The stair is steep, 9.25 in rises on 6.25 in goings (56°, inside the ship-stair range), and deployed it covers the fridge drawers and leaves the toilet only 3.3 in of knee room, so it folds away while the toilet is in use; the rear seats face forward on three-point belts and fold away before the shower wall, the toilet wall or the stair can be used; the toilet’s knee zone overlaps the first left tridem housing’s corner by 4.1 in; the shower is a seated one with the roof down (66.7 in); the crosswise twin has 42.5 in over it at the centreline and 33 in at the walls, and the recesses in both door leaves leave 1.9 in of foam (about R 11 against R 18); with the twin made up, both doors are reached only across the bed, so the passage and deck sleepers climb onto its end, 26 in up, to get out; from the right door to the passage the way is across the shower pan, with its wall open and the right seat folded, or through 11.3 in behind the chair, and the left door goes straight onto it; the washer-dryer’s door faces forward over the shower, so it is loaded from the shower pan; the tridem pitch is 40.4 in, 0.4 in over the 40 in rule, with 4 in between the tires (3.1 in to the counter-steered last tire); the couchbed leaves only 9–12 in beside it in bed mode; and nothing is left under the deck for storage. The front tire’s outer face (41.2 in) reaches the full body width at the nose chin, so the arch opens from the chin; at full lock the inner tire’s corner swings 8.9 in outside the body side, through the open arch. The tridem moved 0.09 m forward to clear the undercut tail; below the 24.5 in skirt the last tires reach behind the tail chin, and the last arches are cut back into the tail corners. The corner legs at 0.25 and 5.75 m are not yet placed against the rounded ends: below about 45 in the ends are narrower than the wall line there, and the rear pair falls within the last wheel housings’ length. Coach-style side hatches have no room between the tridem tires, so service is through the tail hatch and lift-out deck panels.
Generator. The noise levels are targets with the insertion loss they need, not predictions; the enclosure, its labyrinths and silencers have to be built and measured. The tank and generator compartments follow the NFPA 1192 rules as summarized in secondary sources, but their vents, liners and access are not designed. Charging the traction pack from the generator likely needs an on-road certified engine (EPA 40 CFR 1036.5) even while parked, so that connection waits for EPA.

Images on this page are AI-generated concept renders made from text prompts. They show the intended look; the dimensions in the drawing and tables govern. Prices are dated published references or editable assumptions, not quotes.

Other designs →SKIF trailer ↗

Low enough to park.
Tall enough to live.

The whole vehicle,
in pictures.

One capsule.
A low cockpit, a high deck.

Drive low.
Live up on the deck.

Drive it low.
Raise it at camp.

Nine feet over the deck.
On a twenty-foot footprint.