Flying #532
Posted: Sat Nov 03, 2012 10:37 pm
I am no expert but when I was getting ready to fly the first flight I was looking for all the information i could get so I decided to write down my experience for anyone who comes after. I finished building #532 in October of 2012 and got it inspected on October 12. Now I had to think about flying it. I had flown cubs and super cubs in the early days of my flying career by towing banners and fish spotting in a Citabria. I have about 300 hours of tail dragger time but that was 25 years ago.I spoke with 2 EAA Flight Advisors and they recommended that I get some super cub time and biplane time if i could find it. The only guy i knew who owned a super cub would not be available for a few months so that was out. I went to Hampton NH and rented a J-3 with an instructor for a few hours that included some good crosswind landings. When I had gotten up to speed i went back to Lawrence Mass. and did some taxi tests to check out that the plane tracked straight and the controls and brskes would as they should. I had been advised by several sources to avoid high speed taxi tests as a large per centage of accidents result from them with questionable return. It seemed like good advise. However I noticed with a power setting of about 1500 rpm as i gained speed i seemed to have to hold in a lot of left rudder and the plane seemed to track about 10 degrees nose right.. Then I remember that the stabilizer was adjustable and I put it in the center spot until I got a chance to test it. I went bsavck to the hangar and put in the offset 1 inch to the left and tried it again.It was much better. So much so that the plane lifted off before I realized it. I am not saying the plane would have been uncontrollable with the stab in the other position be it was certainly more comfortible in the off set position. Anyway the flight advisors had told me to be ready for the possibility of flying before I was expecting too. I had advised the tower of this possibility also so when it happened I had a plan and tower was aware of it.
I had drawn up several flight test cards based on the FAA Advisory Circular AC-90-89A on flight testing homebuilts. For the first flight it recommended climbing out to 1000 feet and keeping the speed at 1.5% of stall speed. By my calculations that was about 53 MPH in a Hatz with a 150 HP Lycoming in it. That would be a pretty low power setting. The FAA circular went on to recommend that several climbs be down 1000 feet at a time up to 5000 feet at different speeds to get the best rate of climb speed. This was to be followed by descents, with the power pulled back, to 1000 feet to get the best glide speed. Then practice slow flight and landings all the time noting the readings of the engine and flight instruments and writting them down.
I mentioned this to my mechanic friends and spoke with the guy who rebuilt my engine and was told in no uncertain terms that if I did this with a new engine before it was broken in I would in all likelyhood ruin it. The Circular might be alright for a used engine but for one that needed to be broken in a different approach was needed. I decided that with my prop and engine combination requiring a 40 hour Phase 1 test period there would be plenty of time to expand the flight envelope. The engine builder and my friends recommended I spend at least 5 hours and 10 hours would be better running the engine at 75% and above an hour at a time. The engine builder went on to recommend I limit my clims to around 500 FPM in order to insure proper engine cooling in the climb until it was broken in. Running a new engine at lower power settings woud not allow the piston rings to seat right and would glaze the cylinders which would lead to excessive oil consumption and require the cylinders be removed and honed before reinstalling them. The climbs and descents could result in thermal shock that cracked those very expensive cylinders and cause them to have to be replaced.
Well not only did that eliminate the climbs and descents but there was no way I could run the engine at 75% and keep it below 53 MPH.
After lift off I informed the tower I was climbing to 2000 feet and would be circling the field at that altitude for the next hour unless a problem developed. I then gentlely moved the controls to see that they responded properly and without any unusual vibrations. Climbing to 2000 feet would put me well above the normal pattern altitude of 1000 feet and 500 feet above the biz jet pattern which should keep me out of the way. I did not reduce power until I reached 2000 feet to avoid the chance of engine failure that often occurs with the first power reduction. At least this way I would have enough altitude to glide back to the field.At 2000 feet I reduced power to 2200 RPM and the speed settled in at about 75 MPH. As the speed increased I was watching for any unusual vibratins or control pressures. Fortunately there were none and I even trimmed the plane out to fly hands off. There was a very slight left wing low tendency but it is so slight that at this point I don't think I will mess with it. I am running an open cowl without an oil cooler which I read in the forum that several guys were doing with O-320's so I was particularly interested in the oil temperature. On climb out it climbed to about 180 F and about 70 PSI on the oil pressure. With various high power settings that the engine builder recommended I use to aid the breaking in process I noticed the oil temperature cimbed to about 220 F which was still well below the 250 F max. I saw in the forum that Steve G was running a little hot and had said that by adding a one inch lip to the bottom of the cowl to improve airflow through the cowl he lowered his oil temp I decided to try it and see what happened.
Towards the end of the hour I pulled the power back to practice some slow flight and got down to 45 -50 MPH with no adverse results. I then desended and reentered the pattern and did a low approach. I normally fly a Citation for work and approach at around 110-120 Kts. When I slowed to about 65 or 70 MPH I felt I was about to fall out of the sky so did the low approach at that speed. I then came around for a landing agsin not feeling comfortible much below 70 MPH. I entered the flsir and of course the plane was no where near being done flying, it floated and floated and then dropped out of the sky and I tested the spring gear pretty well and bounced. At this point I decided to go around. I went around and set up an approach at he proper speed of 45-50 MPH and the plane landed with no spectacular antics. I put a strip of aluminum on the bottom edge of the cowl and when I get bsack from work hope to find the weather still warm enough to try it.
I had drawn up several flight test cards based on the FAA Advisory Circular AC-90-89A on flight testing homebuilts. For the first flight it recommended climbing out to 1000 feet and keeping the speed at 1.5% of stall speed. By my calculations that was about 53 MPH in a Hatz with a 150 HP Lycoming in it. That would be a pretty low power setting. The FAA circular went on to recommend that several climbs be down 1000 feet at a time up to 5000 feet at different speeds to get the best rate of climb speed. This was to be followed by descents, with the power pulled back, to 1000 feet to get the best glide speed. Then practice slow flight and landings all the time noting the readings of the engine and flight instruments and writting them down.
I mentioned this to my mechanic friends and spoke with the guy who rebuilt my engine and was told in no uncertain terms that if I did this with a new engine before it was broken in I would in all likelyhood ruin it. The Circular might be alright for a used engine but for one that needed to be broken in a different approach was needed. I decided that with my prop and engine combination requiring a 40 hour Phase 1 test period there would be plenty of time to expand the flight envelope. The engine builder and my friends recommended I spend at least 5 hours and 10 hours would be better running the engine at 75% and above an hour at a time. The engine builder went on to recommend I limit my clims to around 500 FPM in order to insure proper engine cooling in the climb until it was broken in. Running a new engine at lower power settings woud not allow the piston rings to seat right and would glaze the cylinders which would lead to excessive oil consumption and require the cylinders be removed and honed before reinstalling them. The climbs and descents could result in thermal shock that cracked those very expensive cylinders and cause them to have to be replaced.
Well not only did that eliminate the climbs and descents but there was no way I could run the engine at 75% and keep it below 53 MPH.
After lift off I informed the tower I was climbing to 2000 feet and would be circling the field at that altitude for the next hour unless a problem developed. I then gentlely moved the controls to see that they responded properly and without any unusual vibrations. Climbing to 2000 feet would put me well above the normal pattern altitude of 1000 feet and 500 feet above the biz jet pattern which should keep me out of the way. I did not reduce power until I reached 2000 feet to avoid the chance of engine failure that often occurs with the first power reduction. At least this way I would have enough altitude to glide back to the field.At 2000 feet I reduced power to 2200 RPM and the speed settled in at about 75 MPH. As the speed increased I was watching for any unusual vibratins or control pressures. Fortunately there were none and I even trimmed the plane out to fly hands off. There was a very slight left wing low tendency but it is so slight that at this point I don't think I will mess with it. I am running an open cowl without an oil cooler which I read in the forum that several guys were doing with O-320's so I was particularly interested in the oil temperature. On climb out it climbed to about 180 F and about 70 PSI on the oil pressure. With various high power settings that the engine builder recommended I use to aid the breaking in process I noticed the oil temperature cimbed to about 220 F which was still well below the 250 F max. I saw in the forum that Steve G was running a little hot and had said that by adding a one inch lip to the bottom of the cowl to improve airflow through the cowl he lowered his oil temp I decided to try it and see what happened.
Towards the end of the hour I pulled the power back to practice some slow flight and got down to 45 -50 MPH with no adverse results. I then desended and reentered the pattern and did a low approach. I normally fly a Citation for work and approach at around 110-120 Kts. When I slowed to about 65 or 70 MPH I felt I was about to fall out of the sky so did the low approach at that speed. I then came around for a landing agsin not feeling comfortible much below 70 MPH. I entered the flsir and of course the plane was no where near being done flying, it floated and floated and then dropped out of the sky and I tested the spring gear pretty well and bounced. At this point I decided to go around. I went around and set up an approach at he proper speed of 45-50 MPH and the plane landed with no spectacular antics. I put a strip of aluminum on the bottom edge of the cowl and when I get bsack from work hope to find the weather still warm enough to try it.