BALSA DENSITY CHART

General balsa grading chart as defined by Aero modellers

Grade

Super

Light

 Light Light Medium

Medium

Medium Hard

Hard

Density in lb/cu.ft

4 - 5.4

5.5 - 6.5

6.6 - 7.5

7.6 - 8.5

8.6 - 12

14 +

Suggested Applications for different balsa grades

Ultra Light

4 - 5.4lb

  • Indoor free flight model airframes.

  • Indoor hand or catapult launched gliders (all sheet).

  • Wing, tail and fuselage sheeting on large models that are skinned with fibreglass (straight grain timber).

  • F2C (FAI team race) wings

Light

5.5 - 6.5lb

  • Sheet fill in on built up fuselages.

  • Sheet covering (fuselages and wings).

  • Wing leading edge sheeting.

  • Folding propeller blades and carved indoor propellers.

  • All sheet wings (hand/catapult launched gliders).

  • All wing and tailplane ribs and tip blocks.

  • Engine cowling blocks.

Light medium

6,6 - 7.5lb

  • Sheet fill in on larger models (R/C old-timers).

  • Large section leading and trailing edges.

  • All sheet tail surfaces (C/L and F/F sport).

  • Sheet box constructions (fuselages).

  • Wing ribs (large models).

Medium

7.6 - 8.5lb

  • Spacers on built up box fuselages.

  • Leading and trailing edges.

  • Carved propellers outdoor free flight (folding and free wheeling types).

Medium hard

9 - 12lb

  • Wing spars of large X-section.

  • Auxiliary wing spars (multi spar wings).

  • Fuselage longerons for open frame models.

  • Small section leading and trailing edges.

  • HLG and Catapult launched glider fuselages.

Hard

13lb and up

  • Single main wing spars.
  • Fuselage longerons, 2.5mm sq and under.
  • Auxiliary wing spars of very small X-section.
  • Repairing fences!

Suggested applications for balsa cuts

Please note that there are two (2) basic types of balsa cuts; Quarter grain ( also called Quarter sawn or "C" grain) and Straight grain (also called "A" grain). You may hear reference to "B" grain or random cut which may exhibit some of the characteristics of the two types, often on the same sheet, and with selective cutting, can be used  to produce components with properties nearly equal to that cut from the more desired grain.

Quarter grain (speckled  appearance)

  • Solid wings and tails for HLG and Catapult gliders, control line models and sport R/C models

  • Trailing edges cut from sheet (don't buy pre-shaped stuff, most of it is rubbish, wrong grain and too soft).

  •  Box fuselage sheeting.

  • All wing and tailplane ribs (torsional stiffness).

  • Sheet covering on wings and tailplanes with flat surfaces or shallow curves (resists warping).

  • Built up trailing edges

  • Solid movable surfaces (rudder, elevators, ailerons and flaps)

straight grain

  • Sheeted wing and tail (curved) surfaces.

  • Rib caps.

  • Rolled boom fuselages (mainly free flight).

  • Longerons, spacers and diagonals for open frame and box fuselages.

  • Curved or planked fuselages

  • Leading edge sheeting

  • Wing and tailplane spars and spar webbing

  • Engine cowlings, solid wing tips

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