A Military Air Transport Case is heavier than aluminium, so why cheaper per trip?

Answer: The weight buys rotations. Aluminium loosens after 45 cycles on 14.4 repair hours; this design runs 120 on 7.2, so the denominator grows faster.

Is a lower peak always better?

Answer: No. The bag peaks at 46 g but moves 22 mm and punctures its panel.

When is a plywood crate still right?

Answer: One-way, low-frequency, no return. At 121.7 per trip it needs no return freight.

Where does a plastic case fall short?

Answer: Hinges and corner caps. After 28 rotations the seats crack and repairs reach 10.8 hours.

Which number should be fixed first?

Answer: Reuse count, the denominator for everything else.

Military Air Transport Case: Five Numbers Against Alternatives

Quick answer: Five numbers settle it: weight, peak acceleration in a 1.2 m corner drop, reuse count, cost per trip, repair hours. A Military Air Transport Case weighs 14.2 kg, peaks at 62 g, lasts 120 rotations and costs 23.6 per trip; a plywood crate lands at 121.7.

How Five Numbers Are Measured for a Military Air Transport Case
What 11 kg of Weight Difference Buys
Peak Acceleration in a Corner Drop
Reuse Count Sets the Amortised Cost
When to Go Back to an Ordinary Case
FAQ

1. How Five Numbers Are Measured for a Military Air Transport Case

Five options, one table, and the argument starts: aluminium is light, plywood is cheap, a soft bag swallows odd shapes. Fix the test first: 1100×560×380 mm outer, 8 kg ballast, three corner drops from 1.2 m, accelerometer at 1 kHz.

Option	Empty weight	Price	Design rotations
Military Air Transport Case	14.2 kg	2180	120
Aluminium case	9.8 kg	1650	45
Plywood crate	21.5 kg	320	3
Plastic case	6.4 kg	480	28
Soft bag	3.2 kg	260	12

Rotations follow the failure point: seal face, rivets, hinge seats, zip, strap marks. Weight decides whether two people lift it; the rest fold into one ranking.

2. What 11 kg of Weight Difference Buys

Freight barely notices eleven kilos: volumetric weight at 1:6000 is about 39 kg, more than any case here travels gross, so the airline bills volume. Manpower notices: loaded with 8 kg, a Military Air Transport Case is 22.2 kg, 11.1 kg per hand and inside the 12 kg single-lift limit; the plywood crate is 29.5 kg, 14.8 kg per hand, so most sites call for a trolley.

Military Air Transport Case: four closed olive green cases in a row on a warehouse conveyor, one open on a pallet showing grey foam cut-outs

Light is not easy, heavy is not stiff: the soft bag weighs 3.2 kg on a 5 mm EVA panel, and crate panels soften with moisture.

3. Peak Acceleration in a Corner Drop

Peak and displacement must be read together.

Military Air Transport Case: 62 g, 9 ms, 4 mm, seal still holding 4.5 kPa.
Aluminium: 88 g, 0.3 mm rivet shift, 1.2 mm by the second drop.
Plywood crate: 74 g, cracking at the strap mark on the third drop.
Plastic case: 121 g, an 18 mm corner crack on the first drop.
Soft bag: 46 g, but 22 mm into the inner panel.

Option	Peak	Displacement
Military Air Transport Case	62 g	4 mm
Aluminium	88 g	7 mm
Plywood crate	74 g	9 mm
Plastic case	121 g	12 mm
Soft bag	46 g	22 mm

The bag reaches 46 g by stretching travel and pays in displacement; the rotomoulded shell pairs a low peak with small movement. Foam matters: 30 mm EVA cut to 20 mm lifts the peak to 79 g while displacement falls to 2.5 mm.

4. Reuse Count Sets the Amortised Cost

A Military Air Transport Case is designed for five years at 24 rotations a year, or 120. Aluminium gives out at 45 when rivets loosen, plastic cases at 28, soft bags at 12, plywood at three.

Repairs run back to serviceable: six at 1.2 hours, nine at 1.6, twelve at 0.9, seven at 0.7. At 90 per hour, cost per trip is price plus repairs over rotations.

Option	Repairs	Hours	Cost per trip
Military Air Transport Case	6	7.2	23.6
Aluminium	9	14.4	65.5
Plywood crate	1	0.5	121.7
Plastic case	12	10.8	51.9
Soft bag	7	4.9	58.4

The dearest case per unit is cheapest per trip: a 320 crate over three rotations is 106.7 before downtime.

5. When to Go Back to an Ordinary Case

When all four hold, an ordinary case wins:

Six rotations a year or fewer, inspected after each;
No stacking, no tie-down, moved by hand or trolley;
Road legs under 300 km, no transshipment;
Cargo with its own suspension.

One exception reverses the arithmetic: tie-down rails, over 8 hours of open storage, three-high stacking, −20 °C to 55 °C, or five years of turnover. Open storage is underestimated most: UV and temperature age a shell and the bill appears in year three.

Conclusion

The spread is measurable: 11 kg of weight, 59 g of peak, forty times the rotations, a fifth of the cost per trip. Unit price is a small part of the numerator; the denominator decides, which is why a Military Air Transport Case is hard to displace.

This article discusses only the container (case body) side of specifications and design intent, and does not cover any handling, loading or use of the contents.