From: "Nathan D. Puffer" Subject: COZY: Re: Sixth Flight Date: Thu, 15 Aug 2002 07:19:22 -0700 Dear Marc and Builders, In Newsletter 56, page 5, under Owners Manual changes, we state: Page 25: Delete "Accelerated Stalls" as an approved maneuver. In other words, DON'T DO IT! Best regards, Nat From: marc_zeitlin@hsgmed.com Subject: COZY: Re: Sixth Flight Date: Thu, 15 Aug 2002 09:17:49 -0600 Nat Puffer wrote: >In Newsletter 56, page 5, under Owners Manual changes, we >state: Page 25: >Delete "Accelerated Stalls" as an approved maneuver. In other >words, DON'T DO IT! Why? The only reference to accelerated stalls that I could find was in the description of Pat Young's accident, and it's hard to imagine that you would use the fact that someone with the C.G. in the wrong place, with no vortilons and the wrong canard incidence angle entered a deep stall from an accelerated stall as the basis for this type of restriction. I can understand the requirement for "slow deceleration" for stall entries for the canard type aircraft, but I am not clear at all on why an accelerated stall (just a stall at higher G loading - can easily be at constant speed or very slow deceleration) should be prohibited. Please elaborate on the reasons for this prohibition - I think that it's important to understand the behavior of the aircraft in this mode of operation. -- Marc J. Zeitlin mailto:marc_zeitlin@alum.mit.edu http://users.rcn.com/marc.zeitlin/ http://www.cozybuilders.org/ Copyright (c) 2002 From ???@??? Fri Aug 16 19:40:13 2002 Return-Path: Received: from mx03.mrf.mail.rcn.net ([207.172.4.52] [207.172.4.52]) by mta02.mrf.mail.rcn.net with ESMTP id <20020816041902.PKWF9420.mta02.mrf.mail.rcn.net@mx03.mrf.mail.rcn.net>; Fri, 16 Aug 2002 00:19:02 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx03.mrf.mail.rcn.net with esmtp (Exim 3.35 #6) id 17fYa4-0006Ku-00 for marc.zeitlin@rcn.com; Fri, 16 Aug 2002 00:19:24 -0400 Received: from canard.com (lidar.net [64.246.36.7]) by alum.mit.edu (8.9.2/8.9.3) with ESMTP id AAA28770; Fri, 16 Aug 2002 00:19:23 -0400 (EDT) Received: (from wright@localhost) by canard.com (8.11.6/8.11.6) id g7G4Fmi26767 for cozy_builders-outgoing; Fri, 16 Aug 2002 04:15:48 GMT X-Authentication-Warning: twctex.lidar.net: wright set sender to owner-cozy_builders@canard.com using -f Received: from twctex.lidar.net (root@localhost) by canard.com (8.11.6/8.11.6) with ESMTP id g7G4Fm526762 for ; Fri, 16 Aug 2002 04:15:48 GMT X-ClientAddr: 207.172.4.60 Received: from smtp01.mrf.mail.rcn.net (smtp01.mrf.mail.rcn.net [207.172.4.60]) by twctex.lidar.net (8.11.6/8.11.6) with ESMTP id g7G4Fln26757 for ; Fri, 16 Aug 2002 04:15:47 GMT Received: from 208-59-182-140.s1410.apx1.sbo.ma.dialup.rcn.com ([208.59.182.140] helo=zeitlin-1.rcn.com) by smtp01.mrf.mail.rcn.net with esmtp (Exim 3.35 #6) id 17fYXx-0002dh-00 for cozy_builders@canard.com; Fri, 16 Aug 2002 00:17:13 -0400 Message-Id: <5.1.0.14.2.20020815233753.00a834d0@pop.rcn.com> X-Sender: marc.zeitlin@pop.rcn.com X-Mailer: QUALCOMM Windows Eudora Version 5.1 Date: Fri, 16 Aug 2002 00:14:50 -0400 To: Cozy Builders Mailing List From: "Marc J. Zeitlin" Subject: COZY: Accelerated stall restriction? (Was "Sixth Flight") Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: "Marc J. Zeitlin" Nathan D. Puffer wrote: >Marc Zeitlin as asked "why" accelerated stalls are not approved. > >According to FAR 91.71, acrobatic flight is defined as: an intentional >maneuver involving an abrupt change in an aircraft's attitude, an abnormal >attitude, or abnormal acceleration, not necessary for normal flight." Maybe the concept of accelerated stalls is not entirely clear to all readers. An accelerated stall is any stall performed at a load factor of more than 1 G. This can be performed easily with slow deceleration in a level, banked, coordinated turn. There does not have to be anything abrupt, abnormal, or acrobatic about it. 30 to 45 degree coordinated banked turns are hardly unnecessary for normal flight. The FAR definition of acrobatic flight does not apply here, and no flight school in the USA that performs these maneuvers requires the use of a parachute when doing so. Given that stall-spin accidents are _exactly_ the type of problem that the Rutan canard configuration was designed to prevent, it seems more than appropriate to test the behavior of the aircraft in this configuration and flight maneuver. My Flight Advisor specifically mentioned accelerated stalls as a _required_ maneuver during flight testing. He described his V.E.'s ability to maintain level flight in a 70 degree bank full throttle turn of about 500 ft. radius at approximately a 2.5 G load factor. I don't expect to reach those kind of bank angles, but 45 degrees seems reasonable. >The Cozy Mark IV Owner's Manual, p. 41 says: "No abrupt maneuvers." None will be performed. >Page 25 says: "No acrobatic maneuvers are approved except those listed >below" >It goes on to list as approved: Chandelles, Lazy eights, Steep turns, and >Stalls (No whip stalls, only slow deceleration.). Accelerated stalls were >removed from the approved list in Newsletter 56-5. Yes, and the factual basis for that removal (other than Pat Young's accident) was the basis of my previous question. >The FAA flight standards office says you must obtain approval in your >Operating Limitations in order to do any acrobatic maneuvers. Accelerated >stalls are acrobatic maneuvers. They don't say you need the designer's >approval. If, in fact, we must all obtain approval in the O.L.'s for acrobatics, I'd like to see the O.L.'s for all flying COZY's, and ensure that they all explicitly call out the maneuvers you state. Also, while it is certainly possible to perform an accelerated (or even a 1 G) stall in an acrobatic manner, it is hardly a prerequisite. Since I don't intend to do any aerobatic maneuvers (as defined above), I won't need any extra approvals in my operating limitations, either in Phase 1 or Phase 2. >We have a number of reasons for not recommending acrobatic maneuvers. Non of which, as far as I can see, are related to level flight accelerated stalls, which, until Pat Young's accident, were NOT prohibited in COZY's. >1) The Cozy Mark IV is billed as a comfortable, high performance, family >type, cross country airplane. It is a very poor acrobatic airplane. No doubt. >2) The Cozy Mark IV will not do any stall maneuvers, like snap rolls, spins, >etc. I was hardly suggesting attempting any of these maneuvers. >3) It will not fly upside down. Not for long, anyway, and nor will I, unless I plan to vomit. >4) It builds up speed very rapidly if the nose is pointed down. It would be >easy to develope high g loads. In the hands of an inexperienced acrobatic >pilot, it could be very dangerous. Another reason not to do acrobatics. >5) We have not tested the Mark IV in acrobatic maneuvers, and don't intend >to. Nor I. >6) We think it would be very poor judgement to approve or demonstrate >acrobatic maneuvers in a "family" airplane. Well, OK. I'm not sure what the FAA definition of a "family" airplane is, but it hardly matters in this context. >7) In spite of all the other mitigating circumstances, if Pat Young hadn't >been doing accelerated stalls, he wouldn't have had an accident. On the other hand, if he had built the plane correctly, or at least calculated his CG correctly, he wouldn't have had an accident either. You might as well blame his math skills for his injuries. >If you intend to disregard the designer's advice, at least you should get >permission from the FAA. I don't need permission from anyone, least of all the FAA, to perform non-acrobatic maneuvers in my aircraft. The accelerated stalls I intend to perform are not acrobatic in any way, shape, or form. If a valid aerodynamic or engineering reason for restricting accelerated stalls from the COZY repertoire existed, I'd be happy to avoid them. Thanks for the opinion, though. Best regards...... -- Marc J. Zeitlin mailto:marc_zeitlin@alum.mit.edu http://users.rcn.com/marc.zeitlin/ http://www.cozybuilders.org/ Copyright (c) 2002 From ???@??? Fri Aug 16 19:40:13 2002 Return-Path: Received: from mx03.mrf.mail.rcn.net ([207.172.4.52] [207.172.4.52]) by mta01.mrf.mail.rcn.net with ESMTP id <20020816061234.RDIE2645.mta01.mrf.mail.rcn.net@mx03.mrf.mail.rcn.net>; Fri, 16 Aug 2002 02:12:34 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx03.mrf.mail.rcn.net with esmtp (Exim 3.35 #6) id 17faLZ-0006RS-00 for marc.zeitlin@rcn.com; Fri, 16 Aug 2002 02:12:33 -0400 Received: from canard.com (lidar.net [64.246.36.7]) by alum.mit.edu (8.9.2/8.9.3) with ESMTP id CAA18841; Fri, 16 Aug 2002 02:12:31 -0400 (EDT) Received: (from wright@localhost) by canard.com (8.11.6/8.11.6) id g7G68Ut27023 for cozy_builders-outgoing; Fri, 16 Aug 2002 06:08:30 GMT X-Authentication-Warning: twctex.lidar.net: wright set sender to owner-cozy_builders@canard.com using -f Received: from twctex.lidar.net (root@localhost) by canard.com (8.11.6/8.11.6) with ESMTP id g7G68Uf27018 for ; Fri, 16 Aug 2002 06:08:30 GMT X-ClientAddr: 152.163.225.98 Received: from imo-r02.mx.aol.com (imo-r02.mx.aol.com [152.163.225.98]) by twctex.lidar.net (8.11.6/8.11.6) with ESMTP id g7G68Un27013 for ; Fri, 16 Aug 2002 06:08:30 GMT Received: from JEaton5428@aol.com by imo-r02.mx.aol.com (mail_out_v33.5.) id h.12a.15d07090 (4184) for ; Fri, 16 Aug 2002 02:09:44 -0400 (EDT) From: JEaton5428@aol.com Message-ID: <12a.15d07090.2a8df128@aol.com> Date: Fri, 16 Aug 2002 02:09:44 EDT Subject: COZY: Re: Accelerated Stalls/Aerobatic Maneuvers To: Cozy_builders@canard.com MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_12a.15d07090.2a8df128_boundary" X-Mailer: AOL 6.0 for Windows US sub 10567 Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: JEaton5428@aol.com Dear Nat, Tom, Marc et.al.,
     I try just to "ghost" or "lurk" here since more often than not, I usually don't have
anything to add that others haven't or won't discuss more articulately
than I could, but you have quite "gotten my goat" on this one and I must
respond. I could go on "ad nauseaum" here and recite
chapter and verse FAR's etc, but in the interest of brevity([ too late;-)]
"Quidquid praecipies,esto brevis"; nod to Marc) I'll restrain myself:

1. When someone, in a non-confrontational and appropriate manner,
   requests a reasoned, educational explanation, a "expert" does not
   reply with a response that, in essence, says "because I said so"
2. Accelerated stalls are absolutely not aerobatic maneuvers; they
   are required to be demonstrated on the commercial checkride,
   and during such may not be executed in greater that a 20 degree
   banked turn (+ or - 10 degrees), and are not intended to be, in
   anyway, an abrupt or sudden maneuver.
3. An accelerated stall could very easily be entered during an "over shoot"
   turn from base to final at a low airspeed (anyone who claims not to have
   over shot their turn to final at least once is a liar!), and I wouldn't be
   caught dead (no pun intended) in a plane whose stall characteristics
   in such a circumstance were unknown.

      All in all, to restate the obvious, an accelerated stall can be merely any
stall, power on or off, which occurs at a "higher than normal airspeed"
because of additional load factor induced during any banked turn, even
a shallow bank. It need not be the result of a steep bank, high airspeed,
or an abrupt or vigorous control input or aerobatic maneuver.
     Stalls occur at a given angle of attack, and unless I'm missing something,
the whole concept behind having a canard (at least in this case) is so as a
result of the canards angle of incidence relative to the main wing, it will stall
first, preventing a main wing stall, bla,bla, bla, yadda, yadda, yadda.
The airspeed etc., within reason, at which this happens, shouldn't much matter
for our purposes.
     Nat, if you tell me "do not do accelerated stalls during the test phase"
I will obey you, no big deal, but since this is a very basic maneuver, and
potentially a very easy one to enter during normal flight, if there is
some very good reason why this is unsafe, or this type of aircraft exhibits
some unusual behavior in this situation, you need to explain to us the
aerodynamics of why this is so. It is not enough for me to simply be
"told" what the aerodynamic limitations are; any competent pilot should
also understand "why" certain regimens of flight are unsafe in their
particular aircraft. If there is something dangerous about the Cozy with
regard to accelerated stalls, which I rather doubt in this case, I
doggone well want to know what it is, and why it is!!

Jerry Eaton
MkIV #876 From ???@??? Fri Aug 16 19:40:13 2002 Return-Path: Received: from mx03.mrf.mail.rcn.net ([207.172.4.52] [207.172.4.52]) by mta04.mrf.mail.rcn.net with ESMTP id <20020816124858.FORY17376.mta04.mrf.mail.rcn.net@mx03.mrf.mail.rcn.net>; Fri, 16 Aug 2002 08:48:58 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx03.mrf.mail.rcn.net with esmtp (Exim 3.35 #6) id 17fgXI-0001to-00 for marc.zeitlin@rcn.com; Fri, 16 Aug 2002 08:49:04 -0400 Received: from canard.com (lidar.net [64.246.36.7]) by alum.mit.edu (8.9.2/8.9.3) with ESMTP id IAA24566; Fri, 16 Aug 2002 08:49:01 -0400 (EDT) Received: (from wright@localhost) by canard.com (8.11.6/8.11.6) id g7GCiVN27903 for cozy_builders-outgoing; Fri, 16 Aug 2002 12:44:31 GMT X-Authentication-Warning: twctex.lidar.net: wright set sender to owner-cozy_builders@canard.com using -f Received: from twctex.lidar.net (root@localhost) by canard.com (8.11.6/8.11.6) with ESMTP id g7GCiVa27898 for ; Fri, 16 Aug 2002 12:44:31 GMT X-ClientAddr: 207.217.120.62 Received: from snipe.mail.pas.earthlink.net (snipe.mail.pas.earthlink.net [207.217.120.62]) by twctex.lidar.net (8.11.6/8.11.6) with ESMTP id g7GCiVn27893 for ; Fri, 16 Aug 2002 12:44:31 GMT Received: from 1cust162.tnt1.oberlin.oh.da.uu.net ([65.238.45.162] helo=ix.netcom.com) by snipe.mail.pas.earthlink.net with esmtp (Exim 4.10) id 17fgUG-0001YZ-00 for Cozy_builders@canard.com; Fri, 16 Aug 2002 05:45:57 -0700 Message-ID: <3D5CF4E3.1080401@ix.netcom.com> Date: Fri, 16 Aug 2002 08:49:39 -0400 From: Carl Denk User-Agent: Mozilla/5.0 (Windows; U; Win 9x 4.90; en-US; rv:1.1a) Gecko/20020611 X-Accept-Language: en-us, en MIME-Version: 1.0 CC: Cozy_builders@canard.com Subject: Re: COZY: Re: Accelerated Stalls/Aerobatic Maneuvers References: <12a.15d07090.2a8df128@aol.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: Carl Denk Was said <...Accelerated stalls are _absolutely */not/*_ aerobatic maneuvers;... An accelerated stall could very easily be entered...> I concur with the above, in fact while turning downwind at Sun N Fun 2001, at low speed behind other much slower aircraft, I got a little too much slow and bank combination. The canard washed out, nose headed toward ground, all not instantly. The aircraft behind us (obviously not familar with canards) announced on the radio "THe canard is going in", a little trottle and less bank, and things were back to normal with maybe 50' altitude was lost. If that had been a J-3 cub, PA-18 Super cub, too slow, too much bank, a spin could have occured, and at that altitude, recovery not possible. The object of the test time is to explore all planned and those unplanned situations likely (or maybe should be even unlikely) encountered while over an uncongested area with no risk to passengers or people/property on the ground. At appropriate clearance from ground, and gradually increasing parameters the airframe should be excerised with increasing weights at the allowable limits, and (and I say this with extreme caution) for testing only maybe exceed some of the limits, but I definately would observe the aft CG. During IFR rating training, its common to be presented with unusual attitudes, this would not be the time to end up in an uncontrollable situation. From ???@??? Fri Aug 16 19:40:13 2002 Return-Path: Received: from mx03.mrf.mail.rcn.net ([207.172.4.52] [207.172.4.52]) by mta02.mrf.mail.rcn.net with ESMTP id <20020816144245.KPIJ9420.mta02.mrf.mail.rcn.net@mx03.mrf.mail.rcn.net>; Fri, 16 Aug 2002 10:42:45 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx03.mrf.mail.rcn.net with esmtp (Exim 3.35 #6) id 17fiJg-0001rN-00 for marc.zeitlin@rcn.com; Fri, 16 Aug 2002 10:43:08 -0400 Received: from canard.com (lidar.net [64.246.36.7]) by alum.mit.edu (8.9.2/8.9.3) with ESMTP id KAA26716; Fri, 16 Aug 2002 10:32:54 -0400 (EDT) Received: (from wright@localhost) by canard.com (8.11.6/8.11.6) id g7GESZF28288 for cozy_builders-outgoing; Fri, 16 Aug 2002 14:28:35 GMT X-Authentication-Warning: twctex.lidar.net: wright set sender to owner-cozy_builders@canard.com using -f Received: from twctex.lidar.net (root@localhost) by canard.com (8.11.6/8.11.6) with ESMTP id g7GESZR28283 for ; Fri, 16 Aug 2002 14:28:35 GMT X-ClientAddr: 158.140.2.1 Received: from mailgate.Cadence.COM (mailgate.Cadence.COM [158.140.2.1]) by twctex.lidar.net (8.11.6/8.11.6) with ESMTP id g7GESZn28278 for ; Fri, 16 Aug 2002 14:28:35 GMT Received: from exmbx02sj.global.cadence.com (exmbx02sj.Cadence.COM [158.140.128.151]) by mailgate.Cadence.COM (8.9.3/8.9.3) with ESMTP id HAA17861; Fri, 16 Aug 2002 07:30:02 -0700 (PDT) Received: from exmbx01dall.global.cadence.com ([158.140.136.99]) by exmbx02sj.global.cadence.com with Microsoft SMTPSVC(5.0.2195.5329); Fri, 16 Aug 2002 07:30:02 -0700 X-MimeOLE: Produced By Microsoft Exchange V6.0.6249.0 content-class: urn:content-classes:message Subject: RE: COZY: Re: Accelerated Stalls/Aerobatic Maneuvers MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Date: Fri, 16 Aug 2002 09:30:00 -0500 Message-ID: <8A72FBA2FA41E3469169750A77C3D6CC02F9F0@exmbx01dall.cadence.com> Thread-Topic: COZY: Re: Accelerated Stalls/Aerobatic Maneuvers Thread-Index: AcJFKRfwGsUcZi5hSZqdwAw6RF9utAAB/FSA From: "Ken Reiter" To: "Carl Denk" Cc: X-OriginalArrivalTime: 16 Aug 2002 14:30:02.0197 (UTC) FILETIME=[6818E050:01C24531] X-Received: By mailgate.Cadence.COM as HAA17861 at Fri Aug 16 07:30:02 2002 Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by canard.com id g7GESZR28284 Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: "Ken Reiter" HI Team, I have to second Carl's experience below. Exactly same thing happened to Me three years ago at Osh while holding (circling) over the lake - likewise, Added power and nose came right back up - just be careful. Ken -----Original Message----- From: Carl Denk [mailto:cdenk@ix.netcom.com] Sent: Friday, August 16, 2002 7:50 AM Cc: Cozy_builders@canard.com Subject: Re: COZY: Re: Accelerated Stalls/Aerobatic Maneuvers Was said <...Accelerated stalls are _absolutely */not/*_ aerobatic maneuvers;... An accelerated stall could very easily be entered...> I concur with the above, in fact while turning downwind at Sun N Fun 2001, at low speed behind other much slower aircraft, I got a little too much slow and bank combination. The canard washed out, nose headed toward ground, all not instantly. The aircraft behind us (obviously not familar with canards) announced on the radio "THe canard is going in", a little trottle and less bank, and things were back to normal with maybe 50' altitude was lost. If that had been a J-3 cub, PA-18 Super cub, too slow, too much bank, a spin could have occured, and at that altitude, recovery not possible. From: "Lee Devlin" Subject: Re: COZY: Re: Accelerated Stalls/Aerobatic Maneuvers Date: Fri, 16 Aug 2002 09:05:14 -0600 It seems that the matter of contention in this discussion is a question of degree. An accelerated stall *could* very well be an aerobatic maneuver if done where an abrupt change in attitude would be necessary to induce the desired G loading at the desired test speed. Another issue is whether the 40-hour flight test period is for the purpose of testing the aircraft or the pilot. If I had designed an aircraft, the last thing I'd want is someone with just a few hours in it going out and testing their limits in dealing with simulating life-or-death emergency situations without the benefit of a competent instructor in one of the seats. The FAA removed the need to do spin testing because they realized it was killing more pilots than it was saving. I'd have to agree with this logic. A fatal stall is usually a result of someone doing something that seems natural and intuitive (pulling back) when they see something they want to avoid, namely the ground. The purpose of stall avoidance is to etch into a pilot's brain the need to do something that is highly unnatural, i.e., to see hostile ground coming at you and use the controls to hit it at minimum speed and angle. Recovery from a spin is likely to be something that is very rarely needed unless you intend to get it a spin from flubbing an aerobatic maneuver. If you're learning aerobatics, I'd expect spin training to be a part of it. The FAA removed the need for spin training to enhance safety and Nat, exercising his right as the designer, has removed the need to test accelerated stalls. Not only has he removed it, he's advising against it. If you really wanted to test your ability to get out of unusual attitudes or experience the sensation of an accelerated stall, it would be best to get through the flight test period and then find a competent instructor with time in type and do it as a form of flight training, not as part of testing yourself and the plane at the same time. Lee Devlin Greely, CO From ???@??? Fri Aug 16 19:40:44 2002 Return-Path: Received: from mx03.mrf.mail.rcn.net ([207.172.4.52] [207.172.4.52]) by mta02.mrf.mail.rcn.net with ESMTP id <20020816162935.PBHE9420.mta02.mrf.mail.rcn.net@mx03.mrf.mail.rcn.net>; Fri, 16 Aug 2002 12:29:35 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx03.mrf.mail.rcn.net with esmtp (Exim 3.35 #6) id 17fjz4-00020i-00 for marc.zeitlin@rcn.com; Fri, 16 Aug 2002 12:29:58 -0400 Received: from canard.com (lidar.net [64.246.36.7]) by alum.mit.edu (8.9.2/8.9.3) with ESMTP id MAA09115; Fri, 16 Aug 2002 12:29:52 -0400 (EDT) Received: (from wright@localhost) by canard.com (8.11.6/8.11.6) id g7GGPWw28978 for cozy_builders-outgoing; Fri, 16 Aug 2002 16:25:32 GMT X-Authentication-Warning: twctex.lidar.net: wright set sender to owner-cozy_builders@canard.com using -f Received: from twctex.lidar.net (root@localhost) by canard.com (8.11.6/8.11.6) with ESMTP id g7GGPWC28973 for ; Fri, 16 Aug 2002 16:25:32 GMT X-ClientAddr: 192.25.240.36 Received: from msgbas1.cos.agilent.com (msgbas1x.cos.agilent.com [192.25.240.36]) by twctex.lidar.net (8.11.6/8.11.6) with ESMTP id g7GGPVn28968 for ; Fri, 16 Aug 2002 16:25:31 GMT Received: from relcos1.cos.agilent.com (relcos1.cos.agilent.com [130.29.152.239]) by msgbas1.cos.agilent.com (Postfix) with ESMTP id F00ACD323 for ; Fri, 16 Aug 2002 10:26:58 -0600 (MDT) Received: from axcsbh1.cos.agilent.com (axcsbh1.cos.agilent.com [130.29.152.143]) by relcos1.cos.agilent.com (Postfix) with SMTP id A0865404 for ; Fri, 16 Aug 2002 10:26:43 -0600 (MDT) Received: from 130.29.152.143 by axcsbh1.cos.agilent.com (InterScan E-Mail VirusWall NT); Fri, 16 Aug 2002 10:26:58 -0600 Received: by axcsbh1.cos.agilent.com with Internet Mail Service (5.5.2653.19) id ; Fri, 16 Aug 2002 10:26:57 -0600 Message-ID: From: "ZEITLIN,MARC (A-hsgAndover,ex1)" To: cozy_builders@canard.com Subject: FW: COZY: Re: Accelerated Stalls/Aerobatic Maneuvers Date: Fri, 16 Aug 2002 10:26:55 -0600 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.5.2653.19) Content-Type: text/plain; charset="iso-8859-1" Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: "ZEITLIN,MARC (A-hsgAndover,ex1)" Lee Devlin wrote: >The FAA removed the need for spin training to enhance safety and Nat, >exercising his right as the designer, has removed the need to test >accelerated stalls. Not only has he removed it, he's advising >against it. You bring up a very cogent and applicable point. The FAA removed the spin training requirement from the PPASEL syllabus for exactly the reason that you state - it was killing more people than it was saving, and there was factual data to support this position. Interestingly enough, while Nat advises against accelerated stalls, he has not as of yet provided any factual data to support this change of position. AFAICT, the only rationale for removing the accelerated stalls from the repertoire of COZY maneuvers was that Pat Young entered a deep stall while performing one, notwithstanding the CG, incidence angle, and vortilon problems that actually precipitated the deep stall. I do not believe that these two situations are analogous, due to the asymmetry in reasoning. >If you really wanted to test your ability to get out of unusual >attitudes.... As I and others have previously stated, there is nothing unusual about a 30-45 degree banked turn. Lee, you can't possibly tell me that you haven't banked your L.E. to at least 60 degrees during a normal flight? That you haven't banked to 30-45 degrees during a turn to base or final? >.... or experience the sensation of an accelerated stall, it would >be best to get through the flight test period and then find a competent >instructor with time in type and do it as a form of flight training, >not as part of testing yourself and the plane at the same time. I have now landed my plane 9 times. I have made 9 downwind to base turns, and 9 base to final turns. A couple of them have been at bank angles of 30 degrees or so. If I had not controlled my speed well, and got down to 75 mph, what would the plane have done? If there had been a bit of wind shear, and my airspeed had decreased due to no fault of my own, what would have happened? Do you think that I should find this out at 700 ft. AGL over the center of the city of Fitchburg while concentrating on landing, or whether I should find this out at 4500 ft. over the woods, where I've got some time to recover should something untoward occur? Sorry, Lee, but having performed accelerated stalls in other aircraft, and having been advised as to the theoretical performance of the COZY aircraft in this situation by others who have done it, and having done 1 G stalls in my plane, I find the notion that there's anything unsafe about doing stalls at 1.15 G (30 degree bank) or 1.4 G (45 degree bank) in a level banked turn while at approved CG positions to be extremely bizarre. -- Marc J. Zeitlin mailto:marc_zeitlin@alum.mit.edu http://users.rcn.com/marc.zeitlin/ http://www.cozybuilders.org/ Copyright (c) 2002 From ???@??? Fri Aug 16 19:40:44 2002 Return-Path: Received: from mx03.mrf.mail.rcn.net ([207.172.4.52] [207.172.4.52]) by mta02.mrf.mail.rcn.net with ESMTP id <20020816180200.SVTT9420.mta02.mrf.mail.rcn.net@mx03.mrf.mail.rcn.net>; Fri, 16 Aug 2002 14:02:00 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx03.mrf.mail.rcn.net with esmtp (Exim 3.35 #6) id 17flQW-0003ke-00 for marc.zeitlin@rcn.com; Fri, 16 Aug 2002 14:02:24 -0400 Received: from canard.com (lidar.net [64.246.36.7]) by alum.mit.edu (8.9.2/8.9.3) with ESMTP id NAA28116; Fri, 16 Aug 2002 13:14:31 -0400 (EDT) Received: (from wright@localhost) by canard.com (8.11.6/8.11.6) id g7GHAAu29211 for cozy_builders-outgoing; Fri, 16 Aug 2002 17:10:10 GMT X-Authentication-Warning: twctex.lidar.net: wright set sender to owner-cozy_builders@canard.com using -f Received: from twctex.lidar.net (root@localhost) by canard.com (8.11.6/8.11.6) with ESMTP id g7GHAA529206 for ; Fri, 16 Aug 2002 17:10:10 GMT X-ClientAddr: 208.129.255.5 Received: from goinpostal.extremezone.com (enterprise.extremezone.com [208.129.255.5]) by twctex.lidar.net (8.11.6/8.11.6) with ESMTP id g7GHA9n29201 for ; Fri, 16 Aug 2002 17:10:09 GMT Received: from 0022765262 (i033-2.phx.extremezone.com [208.152.73.33]) by goinpostal.extremezone.com (8.11.3/8.11.3) with SMTP id g7GH3XB59800 for ; Fri, 16 Aug 2002 10:03:33 -0700 (MST) X-Spam-Filter: check_local@goinpostal.extremezone.com by digitalanswers.org Message-ID: <005701c24549$0e10b3e0$214998d0@0022765262> From: "Nathan D. Puffer" To: "Cozy Builders" Subject: COZY: Accelerated stalls Date: Fri, 16 Aug 2002 10:18:36 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: "Nathan D. Puffer" Builders, We may be talking about two different things. I think what is needed here is a definition of accelerated stalls. Making a 2.5g load factor turn at a 45 degree angle of bank is not, by my definition, an accelerated stall or an acrobatic (or aerobatic) maneuver. However, trying to do a snap roll, where you pull the stick back abruptly while in level flight, in an attempt to stall out the main wing and induce roll in a horizontal plane, is an attempt to do an accelerated stall. Likewise, if you are in level flight and suddenly pull the stick back so that you rise vertically until you lose all airspeed, that is also an accelerated stall. If you want an aerodynamic reason, if the Mark IV will not do a snap roll when you pull the stick back abruptly, it would probably go more or less straight up until it runs out of flying speed with the nose pointed up. Your controls would become useless and we don't know what would happen if you start to slide backwards. In our flight testing we found out that we could stall the main wing in level flight if we had too much canard span and a c.g. too far aft, but as long as we had enough forward airspeed so the elevators provided pitch control, we could fly out of it. We NEVER allowed the airspeed to sink to zero, to see if we could get the nose down by shifting the c.g. I would point out that a Velocity got tipped upside down in a jet wash, stalled out upside down, the controls were ineffective, and the pilot could not recover. The pilot described the condition to Center as he was descending and was killed in the resulting crash. What we do not want people to do is to put this airplane in an attitude or condition where the controls are ineffective, like pulling the stick back abruptly while in level flight in an attempt to stall out both the canard and the main wing. We are talking about trying to reach angles of attack way in excess of the angle required to stall out the canard (14 degrees). We are talking about going straight up until you run out of airspeed. We do not know what would happen if you lose all airspeed, are pointed straight up, and the controls are useless. What Marc described as his definition of accelerated stalls does not fit my definition of an accelerated stall. High g, high angle of bank turns are certainly acceptable, and power on stalls are also acceptable, as long as you are in the approved c.g. range. Maybe saying: "No whip stalls" covers this. Hope this clears up this matter. Best regards, Nat From: marc_zeitlin@hsgmed.com Subject: COZY: Accelerated stalls Date: Fri, 16 Aug 2002 12:31:51 -0600 Nathan D. Puffer wrote: >We may be talking about two different things. I think what is >needed here is a definition of accelerated stalls. Making a 2.5g load factor turn at a 45 degree angle of bank is not, by my definition, an accelerated stall ....... First of all, to get a 2.5 G load factor, you'd need to be in a 66.5 degree bank. 45 degree banks will get you a ~1.4 G load factor. Secondly, you do not get to make up your own definitions regarding accelerated stalls. Per AC90-89A, Chapter 5, section 6: "An accelerated stall is NOT a stall reached after a rapid deceleration. It is an in-flight stall at more than one G, similar to what is experienced in a steep turn or pull up." In the interest of objectivity, I will also point out that this section states: "Do not attempt this or any other extreme maneuver unless the designer or kit manufacturere has performed similar tests on a prototype aircraft identical to the amateur-builder's aircraft". Nat has now stated that level banked turns and stalls during those turns are certainly acceptable, as long as you're in the approved CG range. This is ALL I WAS EVER SUGGESTING OR QUESTIONING. >... However, trying to do a snap roll, where you pull the stick back >abruptly while in level flight, in an attempt to stall out the main >wing and induce roll in a horizontal plane, is an attempt to do an >accelerated stall. No, that's a snap roll. That's not at all equivalent to an accelerated stall, although an accelerated stall may be an integral PART of a snap roll. >.... Likewise, if you are in level flight and >suddenly pull the stick back so that you rise vertically until >you lose all airspeed, that is also an accelerated stall. Not necessarily. It depends upon the angle of attack. If the angle of attack never gets higher than the critical angle, than no stall has occurred. Please point out in my previous posts where I was suggesting that maneuver. >...... What we do not want people to do is to put >this airplane in an attitude or condition where the controls are ineffective, like pulling the stick back abruptly while in level flight in an attempt to stall out both the canard and the main wing. Can you please try to address the points and questions that I raised? No one, either myself or anyone else, has in any way suggested an attitude or condition where the controls are ineffective, nor any attempt to create a main wing stall. >......... We are talking about trying to reach >angles of attack way in excess of the angle required to stall >out the canard (14 degrees). No, we are not. You are raising a red herring. Look back at my posts on this subject. Level, banked turns from 30-45 degrees was all I discussed, yes? Slowly decreasing the speed during these turns until the stall AOA (which, by the way, for people's edification does NOT change, no matter how fast you might be going) of the canard (the very same 14 degrees at which the canard stalls in a 1 G stall) is reached is all I was discussing. Please do not try to imply that I EVER suggested anything different. >... We are talking about going straight up until you run out of >airspeed. _YOU_ might be talking about that, but _we_ were discussing accelerated stalls. >What Marc described as his definition of accelerated stalls >does not fit my definition of an accelerated stall. And has been pointed out, you do not get to make up your own definitions - the FAA/EAA/Flight instructors have a perfectly good definition of an accelerated stall - why don't we just use that one? >..... High g, high angle of bank turns are >certainly acceptable, and power on stalls are also acceptable, >as long as you are in the approved c.g. range. Halleluia. This is all I was ever asking about. >..... Maybe saying: "No whip stalls" covers this. >Hope this clears up this matter. There's only one thing that your message cleared up. I apologize to the rest of the mailing list for the argumentative nature of this post. However, I greatly resent the implications that I was suggesting dangerous maneuvers, especially since it is now clear that the only reason for the whole discussion in the first place is that some people do not understand the standard definition of an accelerated stall, or the relationship between AOA and stall speed. -- Marc J. Zeitlin mailto:marc_zeitlin@alum.mit.edu http://users.rcn.com/marc.zeitlin/ http://www.cozybuilders.org/ Copyright (c) 2002 From ???@??? Fri Aug 16 19:41:18 2002 Return-Path: Received: from mx03.mrf.mail.rcn.net ([207.172.4.52] [207.172.4.52]) by mta02.mrf.mail.rcn.net with ESMTP id <20020816194405.XCNV9420.mta02.mrf.mail.rcn.net@mx03.mrf.mail.rcn.net>; Fri, 16 Aug 2002 15:44:05 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx03.mrf.mail.rcn.net with esmtp (Exim 3.35 #6) id 17fn1J-00008m-00 for marc.zeitlin@rcn.com; Fri, 16 Aug 2002 15:44:29 -0400 Received: from canard.com (lidar.net [64.246.36.7]) by alum.mit.edu (8.9.2/8.9.3) with ESMTP id PAA20184; Fri, 16 Aug 2002 15:44:28 -0400 (EDT) Received: (from wright@localhost) by canard.com (8.11.6/8.11.6) id g7GJdYk29866 for cozy_builders-outgoing; Fri, 16 Aug 2002 19:39:34 GMT X-Authentication-Warning: twctex.lidar.net: wright set sender to owner-cozy_builders@canard.com using -f Received: from twctex.lidar.net (root@localhost) by canard.com (8.11.6/8.11.6) with ESMTP id g7GJdXf29861 for ; Fri, 16 Aug 2002 19:39:33 GMT X-ClientAddr: 130.134.81.12 Received: from mailhub.dfrc.nasa.gov (mailhub.dfrc.nasa.gov [130.134.81.12]) by twctex.lidar.net (8.11.6/8.11.6) with ESMTP id g7GJdSn29856 for ; Fri, 16 Aug 2002 19:39:28 GMT Received: from mail.dfrc.nasa.gov by mailhub.dfrc.nasa.gov with ESMTP for cozy_builders@canard.com; Fri, 16 Aug 2002 12:32:49 -0700 Received: from PC6600001244.dfrc.nasa.gov ([130.134.49.56]) by mail.dfrc.nasa.gov (Post.Office MTA v3.5.3 release 223 ID# 0-71686U2500L200S0V35) with ESMTP id gov for ; Fri, 16 Aug 2002 12:37:11 -0700 Message-Id: <5.0.0.25.2.20020816115736.00aae7a8@mail.dfrc.nasa.gov> X-Sender: Kevin.Reilly@mail.dfrc.nasa.gov X-Mailer: QUALCOMM Windows Eudora Version 5.0 Date: Fri, 16 Aug 2002 12:35:51 -0700 To: Cozy Builders From: Kevin Reilly Subject: COZY: Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="=====================_17176598==_.ALT" Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: Kevin Reilly

All,
Realizing that the guidance given in Advisory Circular 90-89A, Amateur-Built Aircraft and Ultralight Flight Testing Handbook, provides only suggestions and safety related recommendations, it does provide some commentary for performing accelerated stalls in Section 6, para 1a, p56 (Bolding is the FAA's, not mine):

1...a. "An accelerated stall is not a stall reached after a rapid deceleration. It is an in-flight stall at more than one G, similar to what is experienced in a steep turn or a pull up. Note: Do not attempt this or any other extreme maneuver unless the designer or kit manufacturer has performed similar tests on a prototype aircraft identical to the amateur-builder's aircraft.

b. The two standard methods for accelerated stalls are the constant g (constant bank) and constant speed (increasing bank). Most preferred of the two is the constant bank method in which airspeed is decreasing and the angle of bank is held constant, until the aircraft stalls. It is the most preferred because the potential violence of any accelerated stall is largely governed by the increasing g load and airspeed.

c. As with every test, plan the sequence of events. Start with small bank angles -- 30 degrees will produce 1.15 g. Decelerate slowly, ball in the center, do not over control. Work up incrementally to a two g, 60 degree bank.

d. The aircraft does not have to develop a deep stall each time. The pilot needs only to record the airspeed and bank angle in which the aircraft hits the pre-stall buffet. Recover by adding power and reducing the angle of bank."

Nat, during the Cozy flight test, were accelerated stalls performed as described in "b" above (i.e. holding 30 degrees of bank (constant bank)until the aircraft stalled?) If so, I would think that a conservative approach following the recommendations that the FAA stated would be appropriate. If not or if they had not performed accelerated stalls using the constant speed (increasing bank), then folks should heed the FAA's note listed above.
I can see Marc's rationale for wanting to have his aircraft tested in that flight envelope because, for whatever reason, he may eventually find himself flying in that part of the envelope. Nat on the other hand would prefer that builders not attempt to increase a possibly untested part of the Cozy envelope. I'm sure Marc would have used a conservative approach if he was going to attempt it, but we haven't heard which of the two flight test techniques methods Marc was planning to fly.

Anyone wanting a copy of Advisory Circular 90-89A can obtain it at:

http://av-info.faa.gov/dst/amateur/ac90-89a.pdf

Kevin Reilly
NASA Dryden Flight Research Center (DFRC)/SF
Flight Assurance
(661) 276-3862
kevin.reilly@dfrc.nasa.gov From ???@??? Thu Aug 15 23:34:50 2002 Return-Path: Received: from mx03.mrf.mail.rcn.net ([207.172.4.52] [207.172.4.52]) by mta04.mrf.mail.rcn.net with ESMTP id <20020815181948.DKOU16993.mta04.mrf.mail.rcn.net@mx03.mrf.mail.rcn.net>; Thu, 15 Aug 2002 14:19:48 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx03.mrf.mail.rcn.net with esmtp (Exim 3.35 #6) id 17fPDu-0004RE-00 for marc.zeitlin@rcn.com; Thu, 15 Aug 2002 14:19:54 -0400 Received: from canard.com (lidar.net [64.246.36.7]) by alum.mit.edu (8.9.2/8.9.3) with ESMTP id OAA23593; Thu, 15 Aug 2002 14:19:51 -0400 (EDT) Received: (from wright@localhost) by canard.com (8.11.6/8.11.6) id g7FIFTx23467 for cozy_builders-outgoing; Thu, 15 Aug 2002 18:15:29 GMT X-Authentication-Warning: twctex.lidar.net: wright set sender to owner-cozy_builders@canard.com using -f Received: from twctex.lidar.net (root@localhost) by canard.com (8.11.6/8.11.6) with ESMTP id g7FIFTO23462 for ; Thu, 15 Aug 2002 18:15:29 GMT X-ClientAddr: 208.129.255.5 Received: from goinpostal.extremezone.com (enterprise.extremezone.com [208.129.255.5]) by twctex.lidar.net (8.11.6/8.11.6) with ESMTP id g7FIFSn23457 for ; Thu, 15 Aug 2002 18:15:28 GMT Received: from 0022765262 (i072-2.phx.extremezone.com [208.152.73.72]) by goinpostal.extremezone.com (8.11.3/8.11.3) with SMTP id g7FI8s051604; Thu, 15 Aug 2002 11:08:54 -0700 (MST) X-Spam-Filter: check_local@goinpostal.extremezone.com by digitalanswers.org Message-ID: <007301c24489$00bba120$744998d0@0022765262> From: "Nathan D. Puffer" To: , References: Subject: COZY: Re: Re: Sixth Flight Date: Thu, 15 Aug 2002 11:23:50 -0700 MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: "Nathan D. Puffer" Dear Builders, Marc Zeitlin as asked "why" accelerated stalls are not approved. According to FAR 91.71, acrobatic flight is defined as: an intentional maneuver involving an abrupt change in an aircraft's attitude, an abnormal attitude, or abnormal acceleration, not necessary for normal flight." The Cozy Mark IV Owner's Manual, p. 41 says: "No abrupt maneuvers." Page 25 says: "No acrobatic maneuvers are approved except those listed below" It goes on to list as approved: Chandelles, Lazy eights, Steep turns, and Stalls (No whip stalls, only slow deceleration.). Accelerated stalls were removed from the approved list in Newsletter 56-5. The FAA flight standards office says you must obtain approval in your Operating Limitations in order to do any acrobatic maneuvers. Accelerated stalls are acrobatic maneuvers. They don't say you need the designer's approval. We have a number of reasons for not recommending acrobatic maneuvers. 1) The Cozy Mark IV is billed as a comfortable, high performance, family type, cross country airplane. It is a very poor acrobatic airplane. 2) The Cozy Mark IV will not do any stall maneuvers, like snap rolls, spins, etc. 3) It will not fly upside down. 4) It builds up speed very rapidly if the nose is pointed down. It would be easy to develope high g loads. In the hands of an inexperienced acrobatic pilot, it could be very dangerous. 5) We have not tested the Mark IV in acrobatic maneuvers, and don't intend to. 6) We think it would be very poor judgement to approve or demonstrate acrobatic maneuvers in a "family" airplane. 7) In spite of all the other mitigating circumstances, if Pat Young hadn't been doing accelerated stalls, he wouldn't have had an accident. If you intend to disregard the designer's advice, at least you should get permission from the FAA. Best regards, Nat