Weighing A Plane Using Bathroom Scales
By: Doc Green

In attempting to weigh a plane using a single bathroom scale, problems are sometimes encountered in getting reliable and repeatable readings. This is due to flexing of the gear and tires as the plane is jacked up and down repeatedly in the course of moving the scale from one wheel to another. In some cases, side loads are applied that can cause the scales to read inaccurately.

Here is a procedure that will minimize many of these problems. Once the plane is "up on the blocks," no further jacking is required.

  1. First, acquire a suitable scale. Measure its height, including whatever you place on top of the scale to distribute the weight.
  2. Then get 6 pieces of wood about a foot long whose thickness is the same as the height of the scale. (Having a woodshop will help here.)
  3. To weigh the plane, use two pieces of wood for each wheel. Place the pieces of wood in line, one in front of the other. Somehow, get the plane up onto the pieces of wood so that the plane can be rolled backward and forward from the front pieces to the rear pieces, etc.
  4. In rolling the plane back and forth, the lateral extension of the gear should stabilize so that no sideways thrust is being exerted.
  5. To weigh a wheel, roll the plane onto the rear pieces of wood. Remove the front piece of wood at the wheel to be weighed, and substitute the scale. Roll the plane forward onto the scale. Read the weight.
  6. Roll plane backward off the scale, reinsert the piece of wood, and go to the next wheel. And so forth.

And that's all there is to it.

Possible good scale type:

Taylor 5550 - digital strain gauge scale. Ed Burkhead reports this scale stays accurate to within 1-2 lb. even in the range of near 3%# (um-humm) lb. This scale has been checked against doctor's balance scales in four different doctors' offices and matched all. Other higher-end Taylor digital strain gauge scales may well be as accurate. Prices range near $40.