Al wrote:
Many of the same folks that bought the STC operated over gross before they had it. Was it dangerous on Monday before it arrived in the mail and then any less dangerous by Saturday when the A&P with IA installed the valves in the gear and submitted the paperwork? Al, I think the point is, the basic structure of the C and CD model planes is substantially similar to the 1400 lb. allowed D model. On a fundamental level, many people contend it is as safe to fly at 1320 lb. (or 1400 lb.) on Monday without the STC or on Friday after application of the 1320 lb. STC or after doing the model D conversion. The fundamentals of the plane arent changed. Al wrote: So what my contention is that a paper STC has the ability to make many feel that the airplane can do what it actually can't. Thus, the fundamental question is: Is a Coupe safe to fly at 1320 lb. (with STC) or at 1400 lb. (models D, E, G, Forney F-1)? Al wrote: I'll bet your ranch that there was no flight testing involved in the issuance of this STC, only scientific calculations based on the D's abilities and the politics of the parties involved. But if using the D as a benchmark for the structure, how is it that the STC can be issued to the straight C.? As I heard it, the FAA did **extensive** testing before approving the gross weight for the D model. Ive been told that the FAA found that the stall/spin-proof testing of the Coupe at 1400 lb. with the 13° elevator up travel was acceptable. But, they went on to allow for field conditions and inaccurate rigging. The FAA added two extra degrees of elevator up travel and judged the stall/spin-proof behavior was not adequate at 1400 lb. and 15° elevator up travel to maintain the certificated incapable of spinning endorsement. As the 1320 lb. STC requires the elevator limitation to be changed to 9° up travel, this FAA determination doesnt apply. So, where do you feel is the danger in flying at 1320 lb. gross weight? Ill answer this question for me. I admire the Coupes ability to fly at 100-108 mph on 75-85 hp. It has a fairly sleek airframe for the late 1930s or 1940s. But, due to the weight and low power, it climbs slowly marginally slowly, IMHO. I countered this with a 7146 climb prop on my C-85. With that prop, I could safely get out of 1800 no-obstruction grass airports, being off the ground often by mid field and always by 2/3rds of the field. (One (1) exception, at 1400 lb., zero wind, temp 92° or so and grass exceptionally long, we were at 80-85% of the field before I lifted off [no obstructions and plenty of flat cropland to use for airspeed increase and climb].) With that prop, I could always get to 12,500 at 1400 lb. gross weight. (One (1) exception, in turbulence over Nevada I topped out at 11,500 (density altitude 14,500).) I think its reasonable to redefine the C-85 prop selection for Coupes to be 7146 climb, 7148 normal, 7150 cruise, 7152 not recommended unless you are flying at light gross weights, i.e. 1260 lb. (Side note: The sleek airplane that lets the Coupe fly 108 mph on 75 hp also lets it gain speed VERY fast with the nose down. Those who try aerobatics in a Coupe risk over speed and high g-load pull outs and, quite simply, death. Aerobatics are not recommended in Coupes, even though it may not be explicitly prohibited for the C and CD models due to the old style certification rules.) Al wrote: As you, if I could change the rules I would, but I'm afraid that the rules of physics are still a bit tough at this time. Finally, once again, let's not forget how the D mod hurt the LSA status of the Ercoupe without adding anything substantial except a GWI. Maybe it's still a wait and see thing for me. To those of us who are diametrically challenged, an increase in legal gross weigh is a substantial improvement in safety due to the increased fuel allowance for flights. I think the safety record of the D, E, G and all later models gives adequate evidence that the 1320 lb. STC is not a significant risk increase given the correct prop to allow adequate climb. Ed
