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Ramblings on the 320/360 cowl--
This cowling was one of the most labor intensive parts of the building process - it was poorly molded and, of course, required a different lower air inlet for the front servo I/O 320. In addition to that modfication, the air exit area required stiffening as indicated by Lancair's suggestion for a "prop" from the fuselage bottom to the cowl.
Anyway, here are all the things I have done:
1. Rebuilt the front joggle joints around the cooling air inlets and to the prop shaft opening for strength and fit.
2. Added 1 bid (2 inch wide) around all the edges of the upper and lower cowling so that the camloc fasteners would have more glass meat to work with.
3. Replaced the "air scoop".
4. Stiffened the nose gear opening and air exit area by floxing in formed 1/4 inch aluminum tubing and covering with 2-bid.
5. Built "trumpet horns" on the aft side of the cooling air inlets (glassed on the top, screwed into the bottom) to slow down the incoming air.
6. Screwed a curved aluminum plate to the upper cowling (behind the spinner) to stiffen and provide better air control.
7. Built a 3x9 inch access panel under the oil quick drain that also provides easy access to the nose gear strut Schrader valve in addition to allowing oil changes without removing the lower cowling.
8. Installed the Lancair landing light to the left front cowl - lights up the runway on approach (100 watt "leg light" lights runway after flair begun).
9. Installed large NACA duct (left side) for firewall mounted 7-vane oil cooler.
10. Built "hidden hinge" oil filler tube access door.
11. Induction air inlet built to be smooth-walled, about 4 inches long and fits into smooth walled plumber's sleeve to feed ram air direct to throttle body.
And, more lately (since last June's gear up)
12. Carbon fiber "hood" over lower cowling opening for exhaust pipe exit (better airflow).
13. Air exit opening "flare" around outside edge for better exit airflow since Lasar ignition has increased power production, thus heat.
Problems?
Yep, after 400 hours, fine line cracks in the Gel coat (and thus, paint) in the area just above (and closest to) cylinder heads 1 and 2. Probably from excessive heat after shutdown. I have recently ground down this area, filled with micro/cabosil slurry, primed and repainted - time will tell.
Finally, the inside of the cowl was sealed with epoxy primer and painted white. This stops oil from penetrating the cowl glass mat and eventually leading to glass and outside paint deterioration. This also show every oil leak, rub area, etc.
Scott Krueger
N92EX
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