How much larger than the airframe should a drone case interior be?

Answer: 25 mm of foam plus 3 mm of clearance per side, or 8% to 12% of the envelope.

Why do drone cases with the same outline differ in weight?

Answer: Wall and rib layout; with 2.8 mm sides the lid fails under a three-high stack.

Can clamp force be estimated by rule of thumb?

Answer: Roughly, as area times cavity pressure: 2,914 cm² at 350 kg/cm² needs 1,020 tonnes, so 1,250 tonnes holds the flash line.

The case is rated 22 kg, so is 22 kg always safe?

Answer: 22 kg is loaded weight, not allowable load; the handle is proven at 44 kg and the stack at 100 kg for 24 hours.

Which tolerances must appear on the spec sheet?

Answer: Exterior ±2.0 mm, interior ±1.5 mm and lid seam 1.0 mm.

Drone Case Specifications: Size, Wall Thickness and Load

Quick answer: A drone case spec derives backwards from three numbers: the interior from the airframe envelope plus foam, the exterior from the interior plus wall, the load from full weight plus stack height.

Three Numbers Set Every Drone Case Specification
Dimension Chain: Deriving the Interior from the Airframe
Wall Thickness and Clamp Force: Sizing the Machine
Load Paths: Handle, Stacking and Corners
Writing the Spec Sheet: Tolerances and Acceptance
FAQ

1. Three Numbers Set Every Drone Case Specification

A drone case spec sheet built from the outside gets redrawn; fix the interior first.

For a 380 × 340 × 140 mm airframe envelope, 25 mm of foam per side and 3 mm of clearance, the interior lands at 560 × 410 × 215 mm, and walls plus ribs bring the exterior to 620 × 470 × 260 mm at 4.8 kg.

Parameter	Value	Basis
Interior	560 × 410 × 215 mm	Envelope plus foam and clearance
Exterior	620 × 470 × 260 mm	Interior plus wall and ribs
Loaded weight	22 kg	Case, airframe, batteries, spares

Loaded weight is the number most often guessed; battery packs alone vary by 1.5 kg and drive the load rating.

2. Dimension Chain: Deriving the Interior from the Airframe

A dimension chain closes outward from the airframe. Take 380 mm, add 25 mm of foam and 3 mm of clearance per side, and the minimum interior is 436 mm; the drawing says 560 mm, and the extra 124 mm holds the gimbal and spare props.

Drone Case: close-up of black foam inside the case, two long curved slots milled with vertical walls, case rim and lid edge at right

Extra clearance is not safety: each 10 mm adds about 6% to foam volume and 0.3 kg, so drawings hold the allowance at 8% to 12% of envelope size.

A 20 mm lid liner compressing 2 mm onto the airframe clamps it vertically, so clearance cannot become impact travel.

3. Wall Thickness and Clamp Force: Sizing the Machine

Structure sets wall thickness, the process checks it: sides 3.5 mm against squeeze, base 4.5 mm for stack load, lid 3.0 mm over the gasket, each with a 1.5 safety factor.

Clamp force sizes the press. A 620 × 470 mm outline projects 2,914 cm²; at 350 kg/cm² the case needs about 1,020 tonnes, so a 1,250-tonne machine with an 85 mm screw carries the margin. Too small a press flashes.

Item	Value	Note
Projected area	2,914 cm²	From the outline
Cavity pressure	350 kg/cm²	Thin-wall PP with ribs
Clamp force	1,020 tonnes	Area × pressure
Selected press	1,250 tonnes	20% margin

Ribs above 60% of the wall sink the visible face; below 40% they buckle under stack load, so 3.5 mm sides pair with 1.8 mm ribs.

4. Load Paths: Handle, Stacking and Corners

Load runs up through the handle, down through the stack, diagonally through the corners. At 22 kg loaded, the handle is rated at twice static load, 44 kg for an hour without set, and a three-high stack puts 66 kg on the bottom case, tested at 100 kg for 24 hours with the lid deflecting under 2 mm.

Drone Case: black case open on pale grey, flocked lid liner, foam with a round hole and two slots, twin front latches

Corners are the usual omission: R30 thickens the wall past 6 mm and spreads stress, while R10 thins exactly where a stack cracks first.

Moulded handle mounts with four radial ribs remove six screw holes, and a 28 mm TPE overmould lowers palm pressure.

5. Writing the Spec Sheet: Tolerances and Acceptance

A spec sheet exists to be inspected: 620 × 470 × 260 mm without ±2.0 mm lets batches differ by 4 mm, and the foam no longer fits. Tolerances follow function: exterior for stacking, interior for foam, seam for sealing.

Item	Requirement	Method
Exterior	620 × 470 × 260 mm, ±2.0 mm	Caliper, three points
Interior	560 × 410 × 215 mm, ±1.5 mm	Go/no-go gauge
Lid seam	1.0 mm or less	Feeler gauge, perimeter

Temperature counts too: PP at 1.5 × 10⁻⁴ per °C moves a 620 mm outline about 7 mm between -20 and 60 °C, so both tolerances cannot sit plus-side.

Conclusion

Drone case specifications are a chain, not a list: the interior fixes space, the exterior fixes volume and press size, load fixes wall and ribs, tolerance decides whether parts assemble. Written into one sheet, that chain gives quoting, tooling and inspection a common reference, so the drone case specification becomes buildable rather than a drawing.

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.