Carl's 4-Place Bearhawk

8-2-2020

Weight and Balance - Preliminary

Before I routed out the engine for overhaul, I wanted to complete a preliminary weigh and balance to have this information while planning the rest of the build. Sadly, I did not think to take pictures until after the fact.

I placed every component I currently have onto the aircraft to include items such as windshield, engine cowling, boot cowl skins, door skins, floor panels, fuel tanks (main and aux), wing stiffners, engine, engine cooling baffles, propeller, FI components, tail feathers (already covered), etc.

Because this weigh is for planning purposes only, I used 5 bathroom scales instead of calibrated units. I did verify all scales were relatively accurate using a known weight. For the front wheels, I needed to place two scales side-by-side with a board layed across the scales. I also had to make a small ramp so the wheels would roll onto the scales.

For the tail wheel I used a stand with a flat surface and shimmed it up until the aircraft was level longitudinally. Lateral level was obtained with tire pressure.

I only checked the weight one time (for the official weigh I will check it 2-3 times) and came up with the following numbers:

LH Main: 587 lbs

RH Main: 602 lbs

Tailwheel: 65 lbs

Total weight: 1245 lbs

CG as weighed: 8.8"

The arm for my main wheels measured at -1.5" and for the tail wheel it was 196.5".

I am very pleased with the results as I can now use this data to plan the installation of all remaining items and know the exact effect these items will have on the CG of the aircraft. My goal is to have the Empty Weight CG at or slightly forward of the forward limit of 10.5".

I know my plane will be a bit heavier than other projects as I have an IO-540 engine and also will be adding some weight with insulation in the cabin area for my creature comfort.

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