Seaworthy
FOUNDER
Massachusetts
One year ago I purchased 26" Goodyears. My plane was in for annual March 2010 and the tires were installed (a few days ago) . Complete new weigh, recalculation of CG. The STC says the tires should move the datum one inch aft. The weigh and calculations seemed to indicate that the CG remained almost the same perhaps a whisker forward. So I took the PA-12 with the Kenmore STC for the O-320 around the patch.
Full fuel--one 185 lbs pilot---no other weight in the A/C. Took off with full nose up trim. After pattern altitude was reached, throttled back A/C to 2200. "Gee, that's odd, I have to hold stick back with full nose up trim." Abeam the numbers, carb heat, pull power back to 1200 RPM. Nose up to slow, stick gets heavy, stick gets heavier, let go of stick---nose plummets to earth. Add power---land with 16 kts on the nose 20 degrees to right---land at approx 68 MPH to keep control of A/C. Full stop----taxi back and consult with A&P/IA. Left access panel to tail spring retaining nut removed
and three ----three pound bags of lead shot placed in tail. Same take off---pattern altitude---throttle back to cruise, now I have to crank in two turns from full nose up trim to fly straight and level and 2200 RPM. Full stop, taxi back, tell A&P/ IA to remove 26" Goodyears and reinstall 8.5X 6 .
The 26" Goodyears carry a weight penalty of 52 pounds. The additional weight that would be required to allow the plane to fly straight and level with neutral trim and the cost to have same installed aft of the extended baggage would be prohibitive ( to me anyway) The risk/ benefit is not worth it. As it is---I am going to have to put some weight aft to offset the Kenmore STC which moved the engine out from the firewall 2" or more from manufacture.
Just another day in aviation. Perhaps someone local wants 26" Goodyears with two landings on them. The two landings were nice though.
Full fuel--one 185 lbs pilot---no other weight in the A/C. Took off with full nose up trim. After pattern altitude was reached, throttled back A/C to 2200. "Gee, that's odd, I have to hold stick back with full nose up trim." Abeam the numbers, carb heat, pull power back to 1200 RPM. Nose up to slow, stick gets heavy, stick gets heavier, let go of stick---nose plummets to earth. Add power---land with 16 kts on the nose 20 degrees to right---land at approx 68 MPH to keep control of A/C. Full stop----taxi back and consult with A&P/IA. Left access panel to tail spring retaining nut removed
and three ----three pound bags of lead shot placed in tail. Same take off---pattern altitude---throttle back to cruise, now I have to crank in two turns from full nose up trim to fly straight and level and 2200 RPM. Full stop, taxi back, tell A&P/ IA to remove 26" Goodyears and reinstall 8.5X 6 .
The 26" Goodyears carry a weight penalty of 52 pounds. The additional weight that would be required to allow the plane to fly straight and level with neutral trim and the cost to have same installed aft of the extended baggage would be prohibitive ( to me anyway) The risk/ benefit is not worth it. As it is---I am going to have to put some weight aft to offset the Kenmore STC which moved the engine out from the firewall 2" or more from manufacture.
Just another day in aviation. Perhaps someone local wants 26" Goodyears with two landings on them. The two landings were nice though.