Greg stopped by yesterday and dropped off 250lbs of sand that he used for his gross weight testing, so I decided to do my testing today. Because I set my gross at 1950lbs, I actually needed 350lbs of additional weight to hit max gross. I started by putting the sand in the passenger seat (with the seat bottom and passenger stick removed), and belted it in tight so that it couldn’t shift. I had partial fuel at this point, so I was right around Van’s recommended gross weight of 1800lbs and 1.2″ in front of the aft CG limit. I went out and flew at this weight for a bit to determine the impact to the stall speed and handling during landing.
I was still about to get about 1800fpm of climb which is pretty close to Van’s published figures, and the stall speed was only slightly higher.
I then added the bag you see in the passenger floor of the picture above which has 56lbs of tools in it. I also added a couple of scales to the baggage area which weigh 20lbs each. After filling up to full fuel, I was right at 1950lbs and 0.7″ in front of the aft CG limit. I took off at this weight to repeat the same tests. Even taxiing out, I could feel the difference in handling. The extra weight on the tailwheel changed the feel of the steering a fair amount. The takeoff roll felt more sluggish and the climb was noticeably slower at around 1600fpm, but once in the air it felt about the same. I did a couple of stalls which broke at pretty close to the same airspeed as the lighter weight (although I’m sure it was slightly higher). I then flew around for quite awhile at a high power setting to burn off some of the fuel.
While I deviated from Van’s recommendation on the gross weight (which you’re allowed to do as the builder), I thought I prudent to set the maximum landing weight of the airplane to be the same as Van’s recommended gross weight to avoid over stressing the gear. After burning off enough fuel to get down to 1800lbs, I headed back to the airport. Burning off this much fuel brought the CG back to within 0.3″ of the aft CG limit. The plane required noticeably less nose up trim in the approach to landing, but the landing itself felt about the same.
