Yesterday I finished up my required 40 hours. I could sign off the Phase I and II requirements if I choose, but I still have a few other things to do. I also worked thru some aerobatics. Earlier I had done aileron rolls, which require little except raising the nose and then applying aileron (and rudder to center the ball) to roll the plane all the way around. As the plane rolls about the longitudional axis, the nose falls. To lessen this effect, I go to about .5 G as the airplane starts into the inverted portion of the roll.
Loops, Cuban Eights, Barrel Rolls, the Split S and Immelman Turns are more fun. For several flights I explored the vertical capability going up and down, but I never did a good vertical figure. Yesterday I finally put it all together and did some good loops and other figures by diving to 200 mph, pulling up wings level at about 3 G until the airspeed died away, going over the top inverted with about 85 mph. For loops, it was easy to just continue down the other side increasing backstick pressure to create a little over 2 G as the plane accelerated to about 180 mph. The whole thing happens fairly quickly. I was surprised at how well behaved the plane was thru the whole thing. It seems to like to do this stuff and does it without straining.
Wednesday, November 5, 2008
Sunday, November 2, 2008
Now I have a little over 38 hours on the Midget, and must get to 40 hours to meet the minimum FAA certification requirements. Most of the problems have been minor and were solved. There were only 2 problems which required any amount of time to work thru. The first was that it seemed like the plane required too much runway for the takeoff. My static engine rpm was 2200 rpm with my original prop. I installed a slightly larger carb, but that only improved things incrementally. Eventually I installed a different prop and that enabled the engine to run at 2500 rpm. The performance may have improved, but not a lot. Well, in the end, it appears the engine was doing what was expected from day one. Part of the problem was poor technique on my part and the other part was unrealistic expectations. I still can't get the plane off in the distances others claim, but I am getting closer. Most say it should get off the ground in less than 1000'. My best is about 1000', but in general it takes me about 1200'. Maybe I will get better, who knows...
My takeoff technique is to line up on the runway center line with 1 notch of flaps (15 degrees on a grass runway), make sure the tailwheel is centered, release the brakes, go to full power, let the tail remain on the ground until the airspeed reaches 40 mph, then raise the tail. If I raise the tail more quickly, it is sometimes difficult to overcome the tendency of the prop wash to force the plane to the left. As the plane accelerates I set the takeoff attitude and wait for the plane to flyoff the runway. It normally leaves the ground at about 60 mph indicated and accelerates fairly quickly to 75 mph. I raise the flaps at 80 mph and climb at 100 mph indicated with full available power. The plane is well behaved, but definately needs managed during the takeoff roll. Cross winds from the left are naturally more troublesome.
The second problem was that my oil temperature runs higher than I would like. This is fairly common for homebuilts that are tightly cowled. My Midget Mustang is tightly cowled, so after determining that I would need to deal with high oil temperature, I added an oil cooler. After some tinkering, I have managed to get enough air flowing thru the cooler to enable it to cool the oil by up to 16 degrees F. Generally I see at least 10 degrees F of cooling thru the oil cooler. I will continue to work thru this problem. At the current time I pipe air from the cowl inlet directly to the oil cooler thru a 1.5" scat tube. The exhaust of the oil cooler is directed into the cockpit for heat as the fall days are getting cooler and I need some heat in the cockpit. The exhaust hose is 2" scat tubing. The temperature of the air exiting the oil cooler is about 10 to 20 degrees F below the oil temperature. Thus the air entering the cockpit is about 160-180 degrees. The temperatures are measured via termisters and thermocouples and are fairly accurate. I will continue to work on this situation.
Some of the minor things I have worked on include: brake o-ring replacement; a transponder that works ok in Mode A, but will not do Mode C; the failure of the regulator in my standby B&C SD-8 alternator system; a minor fuel leak in the header tank, and a minor adjustment to my cable actuated starter system.
Stalls are uneventful if you ease into them slowly. There is a warning at about 2 mph before the stall. I would describe the warning as a high pitched vibration that I more hear than feel. The plane may fall off on either wing during the stall, but it is not all that excuiting. I generally loose about 200-300 feet of altitude. Pulling into the stall more agressively means the stall will be much sharper and the nose will fall further during the recovery. Speed builds quickly when the nose falls, so stalls with flaps down require some care. I have not done accelerated stall yet.
The plane is well behaved in the landing pattern. I generally fly the downwind leg at 100 mph. Abeam the touchdown point, I lower the flaps 2 notches (out of three total) and slow to 85 mph. I hold 85 until I turn final, where I go to full flaps and 75 mph. Crossing the threshold at 70 works well, but 75 is good too. Once the plane is slowed to 75 mph on final, the runway is no longer visible. My best landings are when I gently over-rotate to touch the tailwheel first. In that case the mains come down softly and stay on the ground. If I touch down in a three point attitude, the plane is not done flying and tends to bounce a little. Touchdowns at 60 mph work out well. Once the tail is on the ground I bring the stick to its aft limit. The plane seems to roll out straight with small rudder inputs during the initial landing roll. As the airspeed decreases, it passes thru a band where more attention is required.
As a summary to this post, the plane and I are getting along well together. It is fun to fly and the freedom to be inverted is great. I had forgotten how good it is to sit on the centerline. My canopy does not have a canopy bow, so the view is absolutely wonderful. It is not my intention to sign off theFAA certification until I complete the aerobatics on my list. At this point, I am extremely impressed at how well everything works. There have been very few failures and everything is working as designed.
My takeoff technique is to line up on the runway center line with 1 notch of flaps (15 degrees on a grass runway), make sure the tailwheel is centered, release the brakes, go to full power, let the tail remain on the ground until the airspeed reaches 40 mph, then raise the tail. If I raise the tail more quickly, it is sometimes difficult to overcome the tendency of the prop wash to force the plane to the left. As the plane accelerates I set the takeoff attitude and wait for the plane to flyoff the runway. It normally leaves the ground at about 60 mph indicated and accelerates fairly quickly to 75 mph. I raise the flaps at 80 mph and climb at 100 mph indicated with full available power. The plane is well behaved, but definately needs managed during the takeoff roll. Cross winds from the left are naturally more troublesome.
The second problem was that my oil temperature runs higher than I would like. This is fairly common for homebuilts that are tightly cowled. My Midget Mustang is tightly cowled, so after determining that I would need to deal with high oil temperature, I added an oil cooler. After some tinkering, I have managed to get enough air flowing thru the cooler to enable it to cool the oil by up to 16 degrees F. Generally I see at least 10 degrees F of cooling thru the oil cooler. I will continue to work thru this problem. At the current time I pipe air from the cowl inlet directly to the oil cooler thru a 1.5" scat tube. The exhaust of the oil cooler is directed into the cockpit for heat as the fall days are getting cooler and I need some heat in the cockpit. The exhaust hose is 2" scat tubing. The temperature of the air exiting the oil cooler is about 10 to 20 degrees F below the oil temperature. Thus the air entering the cockpit is about 160-180 degrees. The temperatures are measured via termisters and thermocouples and are fairly accurate. I will continue to work on this situation.
Some of the minor things I have worked on include: brake o-ring replacement; a transponder that works ok in Mode A, but will not do Mode C; the failure of the regulator in my standby B&C SD-8 alternator system; a minor fuel leak in the header tank, and a minor adjustment to my cable actuated starter system.
Stalls are uneventful if you ease into them slowly. There is a warning at about 2 mph before the stall. I would describe the warning as a high pitched vibration that I more hear than feel. The plane may fall off on either wing during the stall, but it is not all that excuiting. I generally loose about 200-300 feet of altitude. Pulling into the stall more agressively means the stall will be much sharper and the nose will fall further during the recovery. Speed builds quickly when the nose falls, so stalls with flaps down require some care. I have not done accelerated stall yet.
The plane is well behaved in the landing pattern. I generally fly the downwind leg at 100 mph. Abeam the touchdown point, I lower the flaps 2 notches (out of three total) and slow to 85 mph. I hold 85 until I turn final, where I go to full flaps and 75 mph. Crossing the threshold at 70 works well, but 75 is good too. Once the plane is slowed to 75 mph on final, the runway is no longer visible. My best landings are when I gently over-rotate to touch the tailwheel first. In that case the mains come down softly and stay on the ground. If I touch down in a three point attitude, the plane is not done flying and tends to bounce a little. Touchdowns at 60 mph work out well. Once the tail is on the ground I bring the stick to its aft limit. The plane seems to roll out straight with small rudder inputs during the initial landing roll. As the airspeed decreases, it passes thru a band where more attention is required.
As a summary to this post, the plane and I are getting along well together. It is fun to fly and the freedom to be inverted is great. I had forgotten how good it is to sit on the centerline. My canopy does not have a canopy bow, so the view is absolutely wonderful. It is not my intention to sign off theFAA certification until I complete the aerobatics on my list. At this point, I am extremely impressed at how well everything works. There have been very few failures and everything is working as designed.
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