William: Just want to tell you it is really a pleasure to me to read the mails you send to the group. This group is great. With mails like this, we have the oportunity to learn a lot everyday. Thank you very much for sharing your knoledge with us ! Daniel
________________________________ From: William R. Bayne <[email protected]> To: e-tech <[email protected]> Sent: Wednesday, April 22, 2009 1:33:03 AM Subject: Re: [ercoupe-tech] RPM Drop during Climb Out Hi Dan, Dan, John Roach is right that 415-D flight test data the 1320 lb. gross STC was the basis for approval. The difference in gross is 80 lbs. (not 60 lbs.) due to Light Sport limits. The 9º up elevator restriction of the 415-D is entirely unrelated to any "danger of stalling" or "extreme risk". Such is speculation without basis. Fred Weick designed the Coupe under "Air Commerce Manual 04" rules and regulations for airplane airworthiness. These standards were roughly equal to today's "Utility" category. The CAB replaced above standards with "Civil Air Regulations Part 03" 11/13/45. The new "Normal" category structural standard was less strict, and it was further revised effective 12/15/46. Fred did the math and quite logically expected his 415-C design (and existing airframes) would be allowed an increase in gross weight from 1260 to 1400 lbs. in the "normal" category. Unfortunately, one or more CAA people wanted the clear superiority of the Ercoupe design denied the commercial success it deserved. Special sections were inserted which unreasonably penalized its exemplary safe performance. One required that "Two-control (or simplified) airplanes" show lateral stability "... by demonstrating that the airplane will not assume a dangerous attitude or speed when all the controls are abandoned for a period of 2 minutes. This demonstration shall be made in moderately smooth air with the airplane trimmed for straight level flight at Vh (or at Vc, if lower)..., and with rearward c.g. loading. OK so far! Another required that "when it is desired to designate an airplane as a type 'characteristically incapable of spinning,' the flight tests...shall be conducted with: (a) a maximum weight 5% in excess of the weight for which approval is desired, (b) a c.g. at least 3% aft of rearmost for which approval is desired, (c) ...up elevator travel 4º in excess of [angle] to which...travel is to be limited..., (d) ...rudder travel 7º in both directions [beyond angle] to which...travel is to be limited Flight characteristics were STILL acceptable with the full 13º up elevator at 1400 lbs., but only 9º up elevator was approved for operations at the higher gross weight. The effect was NOT improved safety but decreased safety...a betrayal of public purpose. Per Ercoupe Information Letter No. 1 dated Jan. 1., 1956, "In the opinion of the factory, this limitation seriously affected the landing qualities of the Ercoupe (415-D). For this reason the 415-CD was produced instead." (with 13º up elevator, and 1260 lbs. gross.) Henry Berliner knew he could not fight the bureaucrats and make money, so he pulled the plug on the retractible, 4-place and Ercoach twin pusher projects, laid off Fred Weick, and sold Ercoupe assembly, sales and service to Sanders over the next 365 days. Regards, William R. Bayne .____|-(o)-|____. (Copyright 2009) -- On Apr 21, 2009, at 21:15, John Roach wrote: > Dan, > I believe the nine degree up elevator limit in the 1329 lb STC resulted > from the same restriction in the conversion of the C Model to the D > Model. The data for the 1320 lb STC was based on the data used for the C > to D conversion. Thus the question becomes, "Why the restriction for the > conversion of the C to the D?" I have heard several different reasons > but I don't know if any of them are correct. For one reason or another > the FAA required the restriction when the higher gross weight was > approved. Many pilots seem to agree that the heavier plane might be in > danger of stalling with too much full up elevator and, should that > occur, a recovery might be difficult. However, I don't know if that has > ever been proven by a flight test. Another factor that could be involved > is the amount of weight the FAA wants as a buffer over the allowed gross > weight so that someone who misfigures and is "slightly" over gross won't > be at extreme risk. I have had the 1320 gross since it became available > and find that the elevator restriction is not really a problem to me. > > John Roach > N 2427H > > Caliendo Dan wrote: >> >> >> Can anyone explain the 9 degree limit with the 1320 lb STC? If you are >> within >> >> CG limits, I don't see how the extra 60 lbs play a role in 13 degrees >> of elevator. >> >> Dan Caliendo >> Ercoupe Mach 0.14 >> 3658H
