Sunday, April 19, 2009

JET Performance with 150 hp. Fixed Prop.

On a good day, near sea level, my aircraft can climb at a rate of about 700' per min. A small jet has the ability to climb approximately 2,000 ' per min. Which brings me to my story.It was on one of my flights from Dawson Creek B.C. to Abbotsford B.C. 45 min. into the flight one needs to cross the Rockies. Cloud often surround the mountain tops making it hard to get over the ridge in a small plane such as mine. I calculated that I would reach 10,000' above sea level if i were to climb about 200' per min. on my first leg. When we arrived at the mountain base we had only climbed to 9,500' and indeed there were thick cumulus cloud hanging over the mountain peaks. I began to climb over, under, and around the cumulus cloud struggling against the wind currents to get high enough to get over the highest ridge of cloud. I estimated that i would need to climb to at least 11,000' to get over. We were traveling south with a south west head wind. At times our speed dropped to 70 mile per hour with a nose up attitude, stall buzzer buzzing, and the altimeter indicating an altitude loss of 200' per min. Often changing direction to head directly into the wind for added lift i would drop the nose to avoid stalling the aircraft until we escaped the down draft and could once again climb. At this altitude I consider a very good rate of climb to be 200'per min. Sometimes, if you manage to hit an updraft, i can reach climbs of 500' per min. I clearly remember the sigh of relief as I reached 11,200' as I cleared the back side of the highest cloud peak and could correct my flight path for my destination. It is a pilots instinct to keep his aircraft level and I felt myself applying more and more pressure to the stick to keep her level. Glancing down at my altimeter I remember seeing it just spinning like i have never seen it spin before. Glancing at my rate of climb indicator showed us climbing, with a level attitude, at 2,400' per min. In a matter of seconds we went from 11,200' elevation to 13'400'. This presented two concerns: 1/ Elevations exceeding 13000 ft. require either pressurization or oxygen. I had neither. 2/ The airspace I was flying in became a controlled airspace over 13000' and required clearance before entering. So I pulled back the throttle and lowered the nose, with great pressure, and managed to get back to below 13,000'. I then trimmed the aircraft for a cruse with a 200' per min. decent which would give me an easy, efficient, cruse and would reach the next mountain ridge at 10000' well above the highest peak. For a few seconds I knew what it would be like to fly a jet. Sure would be Nice!!