tucsonchris
12-13-2010, 01:53 PM
I’m up and flying my Super Sport after 3 years of building. I always wanted the round bump cowl, but it isn’t really available for the Super Sport, so I had to adapt one myself. Phil Laker graciously agreed to use my plane as the experiment. He donated an old Skystar Series V round cowl with the integrated boot cowl. I wanted a separate boot cowl, like the SS typically has, so I cut off the existing boot and tossed it. Despite the special motor mount that John McBean made that was 2 inches shorter than normal, I still had significant issues.
I started with the stock boot cowl for the SS and attached it to the airframe. This allowed the remaining round cowl halves to be crude fitted around the engine. However, the newer design engine mounts are quite a bit higher then in the past, so I knew a centered propeller would not be possible. To make matters worse, to avoid an “upturned” nose I had to now cut off the bump cowl halves, then move them together up about 1.5 inches, then re-fiberglass. This left the issue of airflow to the radiator, which I’ll get to momentarily.
The paint is Polytone, except for the fiberglass and metal parts, which are Aerothane.
No regrets on the polytone. Prop is the IVO ground adjustable medium. The engine is the 912S. I weighed in empty at 765lbs.
I fashioned my own radiator intake scoop from miscellaneous donor parts, but I was really just guessing as to design. I wish I had done more research first. The vent looked more than adequate to pull in lots of air, but I continually overheated. In fact, on my first flight it boiled over at 280 cht as soon as I hit pattern altitude. It was a short flight. I finally determined that the airflow was simply flowing over the opening, and not into it, especially in level flight.
So I began fashioning bits of aluminum into a variety of scoop shapes, trying to induce air flow. I finally got a design that is functional, but draggy and unattractive, so at some point in the future, I’ll have to do some more fiberglassing.
Some things I’ve noticed about handling. The plane flies hands-off, with no noticeable heavy wing. That was a relief. It climbs at 1300 fpm with light tanks. My cruise seems way too (like 90mph) slow, but I do have a lot of drag issues that have yet to be resolved. I also seem to need every inch of up-trim in order to land with one notch of flaps. And a 65mph approach seems to yield a significant sink rate. All to be worked out in the future.
Tucsonchris
I started with the stock boot cowl for the SS and attached it to the airframe. This allowed the remaining round cowl halves to be crude fitted around the engine. However, the newer design engine mounts are quite a bit higher then in the past, so I knew a centered propeller would not be possible. To make matters worse, to avoid an “upturned” nose I had to now cut off the bump cowl halves, then move them together up about 1.5 inches, then re-fiberglass. This left the issue of airflow to the radiator, which I’ll get to momentarily.
The paint is Polytone, except for the fiberglass and metal parts, which are Aerothane.
No regrets on the polytone. Prop is the IVO ground adjustable medium. The engine is the 912S. I weighed in empty at 765lbs.
I fashioned my own radiator intake scoop from miscellaneous donor parts, but I was really just guessing as to design. I wish I had done more research first. The vent looked more than adequate to pull in lots of air, but I continually overheated. In fact, on my first flight it boiled over at 280 cht as soon as I hit pattern altitude. It was a short flight. I finally determined that the airflow was simply flowing over the opening, and not into it, especially in level flight.
So I began fashioning bits of aluminum into a variety of scoop shapes, trying to induce air flow. I finally got a design that is functional, but draggy and unattractive, so at some point in the future, I’ll have to do some more fiberglassing.
Some things I’ve noticed about handling. The plane flies hands-off, with no noticeable heavy wing. That was a relief. It climbs at 1300 fpm with light tanks. My cruise seems way too (like 90mph) slow, but I do have a lot of drag issues that have yet to be resolved. I also seem to need every inch of up-trim in order to land with one notch of flaps. And a 65mph approach seems to yield a significant sink rate. All to be worked out in the future.
Tucsonchris