Thursday, September 6, 2018

Mr. Sandy Ballast Receives First Passenger Ride In The DOG Aviation RV-12

Due to having done some modifications such as adding the modified “Bender baffle” and moving the voltage regulator onto the baffle … plus, installing interior baggage carpet and padded side panels to the interior I know the weight and balance has changed since the time the first W&B measurements were made.

Because the plan is to do some flight testing with the airplane loaded close to gross weight, felt it prudent to make new weight and balance measurements before blindly trying to test fly the RV-12 near the forward and aft CG (center of gravity) limits. As such, all the fuel was drained from the fuel tank and the airplane was leveled on the scales so new weight measurements could be obtained. For those interested, the procedure for determining weight & balance was covered in the August 10, 2016 post found at the following link.

Performing weight & balance measurements on the RV-12

After taking the new weight measurements, the weight and balance sheets were updated to reflect the changes and per FAA regulations, an updated copy is kept inside the aircraft. Also updated the aircraft maintenance log books as well.

My CG did move forward some as I expected it would from the modifications. As it sits, the DOG aviation RV-12 will hit the forward CG limit when there is only one gallon of fuel left in the tank when I fly solo … and with a 230 pound passenger, the forward CG limit will be hit with 3 gallons of fuel left. So I feel I’m in the sweet spot because I know when the RV-12 gets painted, the CG will move aft … so hitting the forward CG limit after painting should not be an issue when giving rides to most people who are capable of comfortably fitting into the RV-12 cockpit.

Chad (an A&P mechanic that works on lots of airplanes on the field) was nice enough to loan me 230 pounds of sand bags for the test flight …. Thanks Chad!  I borrowed one 50 pound of play sand and three 60 pound bags of tube sand. The plan was to get close to gross weight but not over while keeping near the center of the RV-12’s CG range which is 80.49 inches to 85.39 inches. With myself, 230 pounds of sand, 19 gallons of fuel and no baggage, the takeoff CG was 82.66 inches. Although not perfectly in the center of the CG range 82.66 inches is close enough. In this configuration, the CG will slowly move forward as fuel is burned and at approximately the 3 gallon point the forward CG limit will be met. As such, I plan to fly down to about 5 gallons so as to get close to the forward CG limit and check out the handling. Because the RV-12 is a proven design, I don’t expect any control issues or surprises.

After removing the passenger’s seatback and seat bottom cushion the 50 pound bag of play sand was placed on the passenger seat floor. Because the sand bags have been used quite a bit, some were showings signs of wear … so as an insurance policy, the decision was made to place all the sand bags into trash bags just in case there was an unwanted rupture.
First 50 pound bag of play sand placed into a trash bag and placed on the passenger seat floor.

The next three 60 pound bags of sand are of the tube variety and those were placed upright on the 50 pound bag of sand. This arrangement actually worked out quite well in that the sand bags did not interfere with the flap handle or the ELT mounted on the far right … and more importantly did not interfere with control stick movement. Cargo straps were placed around the bottom of the tube sand bags and fed through the handle for spar pin as an anchoring point to prevent the sand bags from sliding to the left towards the flap handle. A second cargo strap was placed higher up and secured to the fuselage cross brace.
Mr. Sandy Ballast bravely volunteered to become the first passenger to receive a flight in the DOG Aviation RV-12. With the three bags of tube sand positioned two aft and one centered forward there was plenty of clearance between the stick and Mr. Sandy Ballast.

The test flight occurred during a beautiful hot morning. The air was perfectly smooth throughout the flight and even though Mr Sandy Ballast was very quiet during the entire test flight, I think he had a great time as the airplane made tight turns, stalls, and some touch-and-go landings.

There were no surprises during the test flight … the extra weight and warm temperatures (high 80’s) make for a little longer ground roll than when solo. Climb-out was good just not as sporty compared to being solo. Landings were uneventful, but I did notice more brake was required to slow down and the stopping distance was longer than when flying solo. All the things one would expect with a heavy passenger.

The RV-12 is simply a nice flying Light Sport aircraft.