From: alwick@juno.com Date: Wed, 13 Jun 2001 16:06:46 -0700 Subject: COZY: Warning! Canopy Latch sys design change There are around 35 Canards out there with a canopy latching sys I designed a couple years ago. I no longer offer any sys for sale, However.... In Flight testing the latch system I have found that the two compression springs I supplied appear inadequate. They allowed the front edge of the canopy to open 1/16" at high airspeeds. No ones canopy has opened, but we should pretend it has occured. I have since replaced the two compression springs with much stiffer ones. This greatly increases the spring rate at the closed position. If you have my system, a knock off, or something similar, make sure you replace the compression springs with (2) 5.5" long, 1/2" outside diam, .085 wire. I got my springs at Ace aircraft supply, commonly known as Ace Hardware. Spring #199, two required. These springs should be installed to maximize spring rate at closed position. This is accomplished by making sure the springs are almost fully compressed when the handle is pulled full aft. All else hunkey dorey. Enjoy! I post this to the group to cover changed email addresses, re-sales, knockoffs, etc. Sorry, I no longer sell a latch system. As always, anyone not happy with sys, send back for full refund. No questions, doesn't matter how long. -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 N9032U NOW FLYING! 61 hours on engine/airframe ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/tagj. From ???@??? Thu Jul 05 21:29:39 2001 Return-Path: Received: from mx05.mrf.mail.rcn.net ([207.172.4.54]) by mta03.mrf.mail.rcn.net (InterMail vM.4.01.03.23 201-229-121-123-20010418) with ESMTP id <20010705233109.LKUK21891.mta03.mrf.mail.rcn.net@mx05.mrf.mail.rcn.net> for ; Thu, 5 Jul 2001 19:31:09 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx05.mrf.mail.rcn.net with esmtp (Exim 3.31 #2) id 15IIaT-00012t-00 for marc.zeitlin@rcn.com; Thu, 05 Jul 2001 19:31:09 -0400 Received: from twc2.betaweb.com (majordomo@ns.betaweb.com [216.231.140.250]) by alum.mit.edu (8.9.3/8.9.2) with ESMTP id TAA07121; Thu, 5 Jul 2001 19:31:08 -0400 (EDT) Received: (from majordomo@localhost) by twc2.betaweb.com (8.9.3/8.9.3) id LAA20277 for cozy_builders-list; Thu, 5 Jul 2001 11:33:55 -0400 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@canard.com using -f Received: from m12.boston.juno.com (m12.boston.juno.com [64.136.24.75]) by twc2.betaweb.com (8.9.3/8.9.3) with ESMTP id LAA20271 for ; Thu, 5 Jul 2001 11:31:35 -0400 From: alwick@juno.com Received: from cookie.juno.com by cookie.juno.com for <"L941HVjjYzDhN3itp//mkCmbosHXavbSAX134v241YqWSda3iLQtiQ=="> Received: (from alwick@juno.com) by m12.boston.juno.com (queuemail) id F9MDDZT2; Thu, 05 Jul 2001 19:24:15 EDT To: canard-aviators@yahoogroups.com Cc: cozy_builders@canard.com Date: Thu, 5 Jul 2001 16:21:13 -0700 Subject: COZY: new latch design concept Message-ID: <20010705.162121.-457417.0.Alwick@juno.com> X-Mailer: Juno 4.0.11 MIME-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit X-Juno-Line-Breaks: 2-3,10-11,14,21-22,24-29,35-36,41-44,47-52 X-Juno-Att: 0 X-Juno-RefParts: 0 Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: alwick@juno.com I have a proposal for a new latch system. It’s an “outside the box” idea. I know at least 20% of the readers will dismiss it just for that, but what the hey, it’s entertaining anyway. There’s one common pattern to all the latch system failures. All of the pilots thought it was latched, when it wasn’t. Doesn’t matter if the root cause was a bent safety catch that didn’t catch, a handle that was 1/16” short of engaging the mating part, a limit switch that was out of adjustment, a burned out bulb. Always the pilot thought it was latched. And why not? The canopy is closed, the handle is near normal position, everything looks the same, feels the same, sounds the same….. So let’s change that. Let’s make it obvious when it’s not latched. Let’s add new visual, auditory, and textural clues. Not just one, but many. Let’s do it in a simple way. The new sys causes the canopy to automatically open 4” every time it’s not latched. Now you are starting down the runway and you have a new visual clue… the canopy is slightly cocked. You hear louder engine noise when you punch the throttle. Both you and that passenger that distracted you see the gap, feel the air hitting your hands and face. When not latched, the handle is displaced 5” from normal position, not just 1/32”. Now instead of no clue, we have lots of clues. “Yeah, but how is this accomplished?” Forget that. For now, just focus on the value of more clues. How can I add more clues?………………………………. First thought is to move the gas strut so that it lifts canopy 4”. How? Best strut location for cozy is to mount one end at the base of the passenger headrest. On the back side at longeron elevation. Then you only need to mount the other end of strut to a point 5” above (approximately), near the other headrest. Simple. Maybe there is an even better way to add clues. There must be. I also don’t think I could tolerate the handle lock. I have a cad plot (readable in WORD) that uses two compression springs. Provides tight reliable canopy seal. Forces handle forward 5” if canopy not latched. Tested to 200+ mph. I’ll send it to: http://groups.yahoo.com/group/canard-aviators/files/ Please feel free to critique. Methodical pros vs. cons would be most valuable. I have not been thorough in analyzing it, and have no interest in defending it. Just food for thought. -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 N9032U 80+ hours on engine/airframe ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/tagj. From ???@??? Sat Jul 07 00:43:59 2001 Return-Path: Received: from mx05.mrf.mail.rcn.net ([207.172.4.54]) by mta01.mrf.mail.rcn.net (InterMail vM.4.01.03.23 201-229-121-123-20010418) with ESMTP id <20010706052421.QVSH18432.mta01.mrf.mail.rcn.net@mx05.mrf.mail.rcn.net> for ; Fri, 6 Jul 2001 01:24:21 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx05.mrf.mail.rcn.net with esmtp (Exim 3.31 #2) id 15IO6H-0007Kv-00 for marc.zeitlin@rcn.com; Fri, 06 Jul 2001 01:24:21 -0400 Received: from twc2.betaweb.com (majordomo@ns.betaweb.com [216.231.140.250]) by alum.mit.edu (8.9.3/8.9.2) with ESMTP id BAA24748; Fri, 6 Jul 2001 01:24:20 -0400 (EDT) Received: (from majordomo@localhost) by twc2.betaweb.com (8.9.3/8.9.3) id RAA23217 for cozy_builders-list; Thu, 5 Jul 2001 17:25:29 -0400 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@canard.com using -f Received: from thepark.net (mke.ns1.thepark.net [205.243.201.18]) by twc2.betaweb.com (8.9.3/8.9.3) with ESMTP id RAA23211 for ; Thu, 5 Jul 2001 17:23:11 -0400 Date: Fri, 6 Jul 2001 00:16:58 -0500 Message-Id: <200107060016.AA2422801078@thepark.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii From: "Paul Comte" To: "cozy_builders@canard.com" Subject: RE: COZY: new latch design concept X-Mailer: Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: "Paul Comte" With all due respect, An open discussion of components which may, through failure, contribute to increased risk is not "Rubbish". The design/build process is an exercise in Risk Management. (A subject in which Mr. Wick demonstrates a wealth of knowledge.) I am sure I speak for all of us on this list in saying we are delighted Mr. Puffer didn't agree that the LongEZ was just fine "as designed". Along that line of reasoning, Mr. Wick has made every effort to be clear that he is doing things his way and No One should feel obligated to follow his lead. His posts consistently reflect a dedication to logical process, minimizing risk and scientific methodology. It is also clear that a loss of integrity of a major airframe component, especially one which protects the pilot and passengers, is not to be ignored. Choosing not to discuss this issue is a valid position. Attempting to terminate a discussion of a safety issue is inappropriate. Thank you both for your efforts. I'd like to take this opportunity to remind everyone of an issue regarding our posts. E-mail easily becomes part of the author's written legacy. Posts are much more readily accessed from "data vault" archives than possible with printed media. Our posts reflect our community and as one builder pointed out not long ago, submissions to this list have traveled outside our circle. Please consider how your posts may be viewed years from now. At that time your words may have profoundly different meanings than in the "immediate" context of this forum. Be very sure you are willing to have your words "immortal" before clicking "Send". Regards, Paul Comte Milwaukee, WI > -----Original Message----- > From: owner-cozy_builders@canard.com > [mailto:owner-cozy_builders@canard.com]On Behalf Of Nat Puffer > Sent: Thursday, July 05, 2001 6:13 PM > To: alwick@juno.com; canard-aviators@yahoogroups.com > Cc: cozy_builders@canard.com > Subject: Re: COZY: new latch design concept > > > Builders, > Rubbish. You are wasting your time. There are no statistics > showing that > canopy latches cause crashes. What causes crashes is failure > to fly the > airplane. If your canopy is open, you can continue to fly. > But if your auto > engine stops, you go down. > Nat From: "John Slade" Subject: Re: COZY: new latch design concept Date: Fri, 6 Jul 2001 08:52:42 -0400 Al, Paul Compte wrote: >His posts consistently reflect a dedication to logical process, minimizing risk and scientific >methodology. I agree. Nat wrote: >Rubbish. I took this to be an introduction, not a comment. I used to keep all messages from Nat in a special folder because I respected what he had to say. There has not been an addition to that folder for many months. There have been enough reports of canopies opening in flight to convince me that the issue deserves my attention. For those who have not reached Chap 18, I suggest that the solution is a no brainer - make you're canopy per Uli Wolter's Cozy Classic front hinge design. There are plans for it, and there are plenty of airplanes flying around testing it for you. I'm not sure how this design handles latching. Greg Richter's Cozy III has two trunk latches with compression spring stops that keep the canopy open a few inches when not latched (as Al suggests). I'm tempted to retrofit a similar system. I'd like to see the file you posted, Al, but I haven't signed up on the Yahoo system. Could you email it to me. I'll post it on my web site for those who didn't bother going through the Yahoo mill. Regards, John Slade, Cozy MKIV #757, progress: http://kgarden.com/cozy West Palm Beach, FL Subject: COZY: idiot-proof "safety latch" From: "Bob Bittner" Date: Fri, 6 Jul 2001 13:26:13 -0500 The problem is that the canopy sometimes opens. Plain and simple. Who cares why? It's happened in Nat's airplane. It's happened to an experienced Navy test pilot. It's happened in my good friend's Cozy III, and I've read of several others. The evidence is there. It IS a problem. Maybe it won't cause a crash. If everything else is 100% working, and the pilot does what he should, it won't cause a crash. Those pilots that continue to fly the airplane don't end up in an NTSB or FAA database. Those that don't continue to fly the airplane become statistics, and bust their planes so bad we'll never know if it WAS the canopy. However, wouldn't it be nice to know it most likely WAS NOT the canopy coming open? Instead, we're sitting here guessing it was the canopy, because it does sometimes come open. Safety comes from making a design idiot-proof to every extent reasonable. A Cozy is safer than a Glassair because an idiot CAN'T normally spin a Cozy. The existing latch is not at all idiot-proof. How do you tell a passenger that the integrity of the airplane is good, when your preflight briefing includes "what to do if the canopy pops open"? This problem does exist and should be fixed. To not address the problem is like saying, "just duct-tape it closed when you get in, because it's no big deal if it comes open." True, but less than ideal. Over the past couple of nights, I've designed a new, incredibly simple system, and "peace of mind" will justify the effort in making the parts. Please take a look... Thanks to whoever designed the other locking latch system, which inspired this design. It works with existing parts, including C-8, as long as they're built to the 0.7" dimension shown. So, I'll send Marc my drawings for the new system, which can be used with existing safety latches, or, as I plan to do, replace C1-L, C2-L, and the bent spring AL latch. btw, if anyone out there knows who can CNC-cut these parts, there's opportunity to knock out a few sets of these. Thanks --------------------------------------------------- >+ Bob Bittner -=- 507-253-6664 In a world full of people, only some want to fly. Isn't that crazy? -Seal "Nat Puffer" on 07/05/2001 06:17:20 PM To: Bob Bittner/Rochester/IBM@IBMUS cc: Subject: Re: COZY: Cozy Safety Bob, Not bad, but what problem are you trying to solve? Is there a problem? If so, what is it? What proof do you have? Give some statistics, such as FAA accident reports. Too many builders waste their time thinking up solutions to problems that don't exist. Nat From: TwoFieros@aol.com Date: Fri, 6 Jul 2001 17:01:15 EDT Subject: COZY: new latch design suggestions Bob, I have taken a good look at your GIF of the new latching system. I like it and I can see the potential safety imporvements. I have a few suggestions that may help make is a little better. 1. The micro switch should be mounted on SH-3 and not SH-4. Since SH-4 is the moving final catch I can see the micro switch interfering with it falling all the way down and preventing it to fully catch SH-1. Even with vibrations experienced in flight it may vibrate SH-4 enough to pop it loose. 2. This is an issue not addresed in your drawing and regards install more than anything else. SH-1 should be painted a bright red so that it will stand out to the pilot when it is poped back and not latched. There should be a little "pocket" that the lever would tuck into when it is latched to cover up the red paint. Sure, if it was not latched the canopy could be cracked but I don't see a system that would make it crack open. Adding a spring to the canopy would make it pop up but this would also increase the force required to secure the latch and possibly pose a problem if SH-4 vibrated loose. 3. In aviation redundancy is a must. If one system fails you need a back up. I'm sure all of us know about this concept. This latch system laques redundancy. If one item failed in the latch it would not keep the canopy secure. The only redundant part I see is the "shark hook." Simple enough but not enough in my oppinion. One way to increase safety could be to make two assemblies that are separate from each other. Having a separate latch in the rear does pose some problems with actuating it from the front seat. This can be accomplished with some well routed push/pull cables. With two separate systems any unwanted or acidental release of the main lever will not effect the other. 4. The "shark hook" is an ok safety device, simple and effective. I don't see it being effective if SH-1 came open quickly, faster than the catch on the canopy rising. In normal flight conditions this should not be possible but under turbulence I can see it possing a potential problem. These suggestions are just some more food for thought. I do feel that the canopy latch needs improvement. With so many accidents and incidents caused from the canopy opening in flight it should be obvious to everyone that we do in fact have a safety problem. If we looked at history we can see some similar instances but at least they have been addressed. For example the 737's rudder system. For a long time a few 737s would crash and investigators were suspicious of the rudder system but with no flight data recorder logging the position of the rudder it was just speculation. Finally with enough people getting suspisious of the rudder a correction was made by boeing. We are mearly speculating about the canopy being a problem. This Speculation should be enough data to warrant a design change. Sure, some of us may want statistics to show that this is a problem so, I propose that we take a statistical poll... who thinks that the canopy latch system in the plans has potential problems that may lead to accidents or incidents? Tim Hedstrom #925 From ???@??? Sat Jul 07 00:45:37 2001 Return-Path: Received: from mx05.mrf.mail.rcn.net ([207.172.4.54]) by mta03.mrf.mail.rcn.net (InterMail vM.4.01.03.23 201-229-121-123-20010418) with ESMTP id <20010706213529.GNXP21891.mta03.mrf.mail.rcn.net@mx05.mrf.mail.rcn.net> for ; Fri, 6 Jul 2001 17:35:29 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx05.mrf.mail.rcn.net with esmtp (Exim 3.31 #2) id 15IdG5-0002iu-00 for marc.zeitlin@rcn.com; Fri, 06 Jul 2001 17:35:29 -0400 Received: from twc2.betaweb.com (majordomo@ns.betaweb.com [216.231.140.250]) by alum.mit.edu (8.9.3/8.9.2) with ESMTP id RAA24255; Fri, 6 Jul 2001 17:35:28 -0400 (EDT) Received: (from majordomo@localhost) by twc2.betaweb.com (8.9.3/8.9.3) id JAA01094 for cozy_builders-list; Fri, 6 Jul 2001 09:38:26 -0400 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@canard.com using -f Received: from imo-d05.mx.aol.com (imo-d05.mx.aol.com [205.188.157.37]) by twc2.betaweb.com (8.9.3/8.9.3) with ESMTP id JAA01088 for ; Fri, 6 Jul 2001 09:36:07 -0400 From: CozyGirrrl@aol.com Received: from CozyGirrrl@aol.com by imo-d05.mx.aol.com (mail_out_v30.22.) id h.104.5b5ed35 (16788) for ; Fri, 6 Jul 2001 17:28:34 -0400 (EDT) Message-ID: <104.5b5ed35.28778781@aol.com> Date: Fri, 6 Jul 2001 17:28:33 EDT Subject: Re: COZY: idiot-proof "safety latch" To: cozy_builders@canard.com MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="part1_104.5b5ed35.28778781_boundary" X-Mailer: AOL 6.0 for Windows US sub 10513 Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: CozyGirrrl@aol.com Bob,
A simple additional safety would be to have a positive stop for SH-1 at the
second position shown in your drawing (SH-1 swept to rear) thereby negating
inertial overtravel of SH-1 and subsequent disengagement if canopy "popped"
open, then the shark hooks would stand a fighting chance of catching the lugs.
My $0.02 for "last chance" redundancy, Chrissi

Chrissi Bush & Randi Kelcher Cozy MK IV # 957
Chapter Six... we are jigging the fuselage! From ???@??? Sat Jul 07 00:45:45 2001 Return-Path: Received: from mx05.mrf.mail.rcn.net ([207.172.4.54]) by mta01.mrf.mail.rcn.net (InterMail vM.4.01.03.23 201-229-121-123-20010418) with ESMTP id <20010706232052.IEUI18432.mta01.mrf.mail.rcn.net@mx05.mrf.mail.rcn.net> for ; Fri, 6 Jul 2001 19:20:52 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx05.mrf.mail.rcn.net with esmtp (Exim 3.31 #2) id 15Ieu4-0005FL-00 for marc.zeitlin@rcn.com; Fri, 06 Jul 2001 19:20:52 -0400 Received: from twc2.betaweb.com (majordomo@ns.betaweb.com [216.231.140.250]) by alum.mit.edu (8.9.3/8.9.2) with ESMTP id TAA11019; Fri, 6 Jul 2001 19:20:51 -0400 (EDT) Received: (from majordomo@localhost) by twc2.betaweb.com (8.9.3/8.9.3) id LAA02230 for cozy_builders-list; Fri, 6 Jul 2001 11:23:42 -0400 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@canard.com using -f Received: from e1.ny.us.ibm.com ([32.97.182.101]) by twc2.betaweb.com (8.9.3/8.9.3) with ESMTP id LAA02224 for ; Fri, 6 Jul 2001 11:21:22 -0400 Received: from northrelay02.pok.ibm.com (northrelay02.pok.ibm.com [9.117.200.22]) by e1.ny.us.ibm.com (8.9.3/8.9.3) with ESMTP id TAA175076 for ; Fri, 6 Jul 2001 19:11:44 -0400 Received: from d27ml103.rchland.ibm.com (d27ml103.rchland.ibm.com [9.5.39.110]) by northrelay02.pok.ibm.com (8.11.1m3/NCO v4.96) with ESMTP id f66N7Tl142898 for ; Fri, 6 Jul 2001 19:07:29 -0400 Importance: Normal Subject: Re: COZY: new latch design suggestions To: cozy_builders@canard.com X-Mailer: Lotus Notes Release 5.0.5 September 22, 2000 Message-ID: From: "Bob Bittner" Date: Fri, 6 Jul 2001 18:12:10 -0500 X-MIMETrack: Serialize by Router on d27ml103/27/M/IBM(Release 5.0.7 |March 21, 2001) at 07/06/2001 06:12:09 PM MIME-Version: 1.0 Content-type: text/plain; charset=us-ascii Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: "Bob Bittner" Thanks. I love to get a good technical discussion going, and this topic is worthwhile. First, I hope nobody would think that this is intended to replace the SS safety catch. It's only a supplemental improvement. I specifically didn't use the word "catch" anywhere. My airplane will have both. Second, the name comes from the fact that to me (at 3 am yesterday) the handle lock looked like the business end of a shark. whatever. The tops of SH-3 and SH-4 are exactly the same contour.. I intend to paint the inside face of SH-4 flourescent yellow. Then, if the latch isn't completely locked, a yellow line will show. The spring between SH-3 and SH-4 is there to override any forces from the microswitch and turbulence. Note that the microswitch is one with a flat metal lever to smoothly come down on the handle bolt. I may move the microswitch to the top of the handle bolt. I think I would also use epoxy to mount the microswitch, to eliminate any interference between SH-3 and SH-4. Adjustment can be made by turning the hex end of the AN3 handle bold. Mounting the switch on SH-3 would negate indicating whether it's locked. The switch location on SH-4 combines meeting the handle bolt and the position of SH-4. In terms of redundancy, the only thing added by the system is the hook part. The shark part (the handle lock) is simply a better version of the spring AL plate with a 9/16" hole. If you've seen Nat's plane, there's a similar system there. There's practially no redundancy in the plans system. The hook design creates an element of redundancy. Perhaps a good idea is to reverse the bolt order which contains SH-4. Then, the pilot would more easily see if the nut was loose. Accidental unlatch: It would take a LOT of negative Gs (I haven't done that math yet, but I will) for SH-4 to be lifted against the spring. Suffice it to say you're a lump of sludge in the top of the canopy before that many -Gs. There's a lot of friction to turning SH-1. It would not likely continue to rotate in the instant that the canopy stops moving. Note that the canopy opening inertia is not continuious, unlike the plans system. With the hook system, it must lift, stop, and lift again. This accelleration takes time, benefitting the hook's ability to grab the canopy. The fit between the hook and the space inside C-8 is very small at the crtitcal catch point. That point is exactly 10.0 degrees from the red position shown on the diagram. Still, to eliminate the possibiltiy of SH-1 freely turning past the catch point, I will add a tension spring from the pushrod mount on SH-1 to a bracket on the instrument panel. I'm not, by any means, calling this system perfect. But, I will defiantly call it better than the plans system, with two exceptions: 1. It's not very tolerant of sloppy measurement. It needs at least very close to the distance provided by the 0.7" dimension for C-8. 2. It's slightly trickier to open. You can't just bump the handle and push up on the canopy. In emergency egress, or with canopy deformation, this could be an issue. All, lets continue this discussion until we can't think of ways to improve it yet retain its simplicity. In case it's not obvious, yes, I've thought about this a lot. :-) Thanks Bob TwoFieros@aol.com@canard.com on 07/06/2001 04:01:15 PM Please respond to TwoFieros@aol.com Sent by: owner-cozy_builders@canard.com To: cozy_builders@canard.com cc: Subject: COZY: new latch design suggestions Bob, I have taken a good look at your GIF of the new latching system. I like it and I can see the potential safety imporvements. I have a few suggestions that may help make is a little better. 1. The micro switch should be mounted on SH-3 and not SH-4. Since SH-4 is the moving final catch I can see the micro switch interfering with it falling all the way down and preventing it to fully catch SH-1. Even with vibrations experienced in flight it may vibrate SH-4 enough to pop it loose. 2. This is an issue not addresed in your drawing and regards install more than anything else. SH-1 should be painted a bright red so that it will stand out to the pilot when it is poped back and not latched. There should be a little "pocket" that the lever would tuck into when it is latched to cover up the red paint. Sure, if it was not latched the canopy could be cracked but I don't see a system that would make it crack open. Adding a spring to the canopy would make it pop up but this would also increase the force required to secure the latch and possibly pose a problem if SH-4 vibrated loose. 3. In aviation redundancy is a must. If one system fails you need a back up. I'm sure all of us know about this concept. This latch system laques redundancy. If one item failed in the latch it would not keep the canopy secure. The only redundant part I see is the "shark hook." Simple enough but not enough in my oppinion. One way to increase safety could be to make two assemblies that are separate from each other. Having a separate latch in the rear does pose some problems with actuating it from the front seat. This can be accomplished with some well routed push/pull cables. With two separate systems any unwanted or acidental release of the main lever will not effect the other. 4. The "shark hook" is an ok safety device, simple and effective. I don't see it being effective if SH-1 came open quickly, faster than the catch on the canopy rising. In normal flight conditions this should not be possible but under turbulence I can see it possing a potential problem. These suggestions are just some more food for thought. I do feel that the canopy latch needs improvement. With so many accidents and incidents caused from the canopy opening in flight it should be obvious to everyone that we do in fact have a safety problem. If we looked at history we can see some similar instances but at least they have been addressed. For example the 737's rudder system. For a long time a few 737s would crash and investigators were suspicious of the rudder system but with no flight data recorder logging the position of the rudder it was just speculation. Finally with enough people getting suspisious of the rudder a correction was made by boeing. We are mearly speculating about the canopy being a problem. This Speculation should be enough data to warrant a design change. Sure, some of us may want statistics to show that this is a problem so, I propose that we take a statistical poll... who thinks that the canopy latch system in the plans has potential problems that may lead to accidents or incidents? Tim Hedstrom #925 From: alwick@juno.com Date: Fri, 6 Jul 2001 16:25:24 -0700 Subject: Re: COZY: See Bittner's Shark Latch System!!! I can't access the canard files, so thanks for making this avail on your site Wayne. Nice work Bob. I really like the concept. I am a little puzzled. The canopy is open full, I'm taxiing around. A breeze comes up, I better shut it for a moment here.... So in that case, can the canopy rest on top of your SH-1 and -2's instead of in the hook zone? Is that intended? If it rests on top of your engagement hooks, it would probably also trip the limit switch into thinking all was well. I agree with comment to move limit switch to protected zone. I placed mine in back seat area below longeron, behind the latch. I'd convert extension spring to compression spring. Whenever heat treat or alloy are not tightly controlled, extension springs break at the sharp bend. Compression springs have no high stress locations. I want to see rev 2. I like the thought process. -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 N9032U 80+ hours on engine/airframe On Fri, 6 Jul 2001 17:20:30 -0400 Wayne Hicks writes: > > I've posted a drawing of Bob Bittner's proposed canopy latch safety > system > (a.k.a, the "Shark Hook") on my website. > > ================================ > Wayne Hicks > Cozy IV Plans #678, Chapter 24 Armrests and Seats > http://www.geocities.com/yosemite/falls/2027 > > ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/tagj. From ???@??? Sat Jul 07 00:45:45 2001 Return-Path: Received: from mx05.mrf.mail.rcn.net ([207.172.4.54]) by mta05.mrf.mail.rcn.net (InterMail vM.4.01.03.23 201-229-121-123-20010418) with ESMTP id <20010707001633.MNWW29110.mta05.mrf.mail.rcn.net@mx05.mrf.mail.rcn.net> for ; Fri, 6 Jul 2001 20:16:33 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx05.mrf.mail.rcn.net with esmtp (Exim 3.31 #2) id 15Iflx-0007XP-00 for marc.zeitlin@rcn.com; Fri, 06 Jul 2001 20:16:33 -0400 Received: from twc2.betaweb.com (majordomo@ns.betaweb.com [216.231.140.250]) by alum.mit.edu (8.9.3/8.9.2) with ESMTP id UAA19122; Fri, 6 Jul 2001 20:16:32 -0400 (EDT) Received: (from majordomo@localhost) by twc2.betaweb.com (8.9.3/8.9.3) id MAA02798 for cozy_builders-list; Fri, 6 Jul 2001 12:18:59 -0400 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@canard.com using -f Received: from mtiwmhc21.worldnet.att.net (mtiwmhc21.worldnet.att.net [204.127.131.46]) by twc2.betaweb.com (8.9.3/8.9.3) with ESMTP id MAA02790 for ; Fri, 6 Jul 2001 12:16:38 -0400 Received: from paul ([12.80.52.43]) by mtiwmhc21.worldnet.att.net (InterMail vM.4.01.03.16 201-229-121-116-20010115) with SMTP id <20010707000907.REXW3208.mtiwmhc21.worldnet.att.net@paul> for ; Sat, 7 Jul 2001 00:09:07 +0000 From: "Paul Stowitts" To: Subject: RE: COZY: Cozy Safety Date: Fri, 6 Jul 2001 17:10:01 -0700 Message-ID: <000301c10679$47b77760$6401a8c0@paul> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook 8.5, Build 4.71.2173.0 X-MimeOLE: Produced By Microsoft MimeOLE V5.50.4133.2400 Importance: Normal In-Reply-To: <3B44C145.F83937E7@starband.net> Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: "Paul Stowitts" Having been in a Cozy with an open canopy, I can attest that it is not fun. I was flying right seat with a friend in his Cozy doing T&Ls. We had just landed and we're taxiing back so he opened the canopy for air. He closed the canopy and we took off down the runway. Just as we were lifting off, the canopy started to open but then stopped. Suddenly it sprang all the way open. The first thought was disbelief and I won't say what my next thought was! Needless to say, our headsets, hats and glasses were ripped off of our heads instantly. (Losing one's glasses could be critical if your eyesight is not good. Seems like keeping a second pair handy might not be a bad idea.) Without the headsets, we could not speak to each other. The wind in our faces was intense. The pilot continued to fly the plane and I made an attempt to close the canopy but could not. After a few moments, I realized that he would have to close it while I flew the plane. So I took the controls and noticed that we were not very high (a few hundred feet at most) and our airspeed was about 85 MPH (critical considering his canard stalls around 80). Fortunately we had nothing in front of us so we could continue without having to turn. While the plane did continue to fly, it didn't like it very much (nor did I). He was able to close the canopy and we immediately returned to the airport. After gathering our wits on the ground we went over what had happened. He thought he had latched the canopy but figured he must not have. His comment was "that's what I get for not using a checklist." The safety catch caught the canopy at first but then released it (just as what Nat reported happened with his test pilot). It happened at the same moment we lifted off (a bad time to get distracted) so we had to continue into the air. After we lost our headsets, we could not speak to each other. Communication was difficult at best as we were both occupied with the situation. It was also difficult to look forward with the wind so I looked off to the side. It is one thing to say what you will do in an intense situation yet the mind does strange things when it actually happens. You must fight yourself to stay in control and perform the necessary actions. Given our situation, there was literally no time to make a decision. Had we taken our hands off the stick for a split second to grab the canopy as it was flying open, I don't think we would have come down in one piece. With that said, I would, in an instant, replace the stainless steel safety catch with one made of spring steel. As far as modifying the system for an obvious unlatched situation, why not examine it? We are all human and we all make mistakes. Anything that can minimize the risks is certainly worth looking into. Paul Stowitts Cozy Mark IV N166PT From: alwick@juno.com Date: Fri, 6 Jul 2001 23:13:02 -0700 Subject: Re: COZY: Cozy Safety Paul, I really appreciate your sharing your story. Did the headsets end up in back seat? Did they stay plugged in? I think of headsets as prop destroyers and wondered where they go. I'm very concerned about a design change that might delay canopy open until you reach ....say 110 mph instead of 85. At 110 the failure may cause headset to hit prop, or canopy departing. Know what I mean? Did you see any marks or distortion on safety catch. Something to explain the nature of it's failure? I sure appreciate your detail and descriptions. I pay a lot of attention to these testimonials, as I know they predict failures and root cause patterns that may happen to me. I much prefer to learn from others experience. I've been very concerned about "tooting my own horn", particularly when I'm already in hot water for being critical of latch design. But I have a good latch sys and think it's my obligation to explain how it works. My cockpit has a laptop that monitors darn near everything. There is an image of a cozy that takes up 20% or the display. I make use of limit switches to show the status on my LCD. So if the canopy is open the display shows an open canopy flashing red. If my safety is off, it shows that also. When I latch the canopy, then you see green closed canopy on the screen. Seeing both open and closed status let's you know Limit switches are operational. I don't have the plans safety catch, nor handle lock. No fuselage door. My handle uses compression springs to lock it. This has some substantial benefits. The release handle is under great pressure to move forward, and does if the canopy is not locked. So a limit switch on my handle is tripped only when the canopy is truly locked, not if the handle is in a certain position. I also have an independant latch. It clicks loudly when engaged and has limit switch that verifys full lock. It also has safety interlock so it's impossible to inadvertantly release lock. My computer recognizes that I'm about to take off with unlatched canopy. It tells me in my headset as I start my takeoff roll. I know my sys is much safer than the plans version, but I'm always convinced there is an even better way to do it. -al On Fri, 6 Jul 2001 17:10:01 -0700 "Paul Stowitts" writes: > Having been in a Cozy with an open canopy, I can attest that it is > not fun. > I was flying right seat with a friend in his Cozy doing T&Ls. We > had just > landed and we're taxiing back so he opened the canopy for air. He > closed > the canopy and we took off down the runway. Just as we were lifting > off, > the canopy started to open but then stopped. Suddenly it sprang > all the > way open. > > The first thought was disbelief and I won't say what my next thought > was! > Needless to say, our headsets, hats and glasses were ripped off of > our heads > instantly. (Losing one's glasses could be critical if your eyesight > is not > good. Seems like keeping a second pair handy might not be a bad > idea.) > Without the headsets, we could not speak to each other. The wind in > our > faces was intense. > > The pilot continued to fly the plane and I made an attempt to close > the > canopy but could not. After a few moments, I realized that he would > have to > close it while I flew the plane. So I took the controls and noticed > that we > were not very high (a few hundred feet at most) and our airspeed was > about > 85 MPH (critical considering his canard stalls around 80). > Fortunately we > had nothing in front of us so we could continue without having to > turn. > While the plane did continue to fly, it didn't like it very much > (nor did > I). He was able to close the canopy and we immediately returned to > the > airport. > > After gathering our wits on the ground we went over what had > happened. He > thought he had latched the canopy but figured he must not have. His > comment > was "that's what I get for not using a checklist." The safety catch > caught > the canopy at first but then released it (just as what Nat reported > happened > with his test pilot). It happened at the same moment we lifted off > (a bad > time to get distracted) so we had to continue into the air. After > we lost > our headsets, we could not speak to each other. Communication was > difficult > at best as we were both occupied with the situation. It was also > difficult > to look forward with the wind so I looked off to the side. > > It is one thing to say what you will do in an intense situation yet > the mind > does strange things when it actually happens. You must fight > yourself to > stay in control and perform the necessary actions. Given our > situation, > there was literally no time to make a decision. Had we taken our > hands off > the stick for a split second to grab the canopy as it was flying > open, I > don't think we would have come down in one piece. > > With that said, I would, in an instant, replace the stainless steel > safety > catch with one made of spring steel. As far as modifying the system > for an > obvious unlatched situation, why not examine it? We are all human > and we > all make mistakes. Anything that can minimize the risks is > certainly worth > looking into. > > Paul Stowitts > Cozy Mark IV N166PT > -al wick Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5 N9032U 80+ hours on engine/airframe ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/tagj. From ???@??? Sun Jul 08 22:57:59 2001 Return-Path: Received: from mx05.mrf.mail.rcn.net ([207.172.4.54]) by mta03.mrf.mail.rcn.net (InterMail vM.4.01.03.23 201-229-121-123-20010418) with ESMTP id <20010708184814.ENVB21891.mta03.mrf.mail.rcn.net@mx05.mrf.mail.rcn.net> for ; Sun, 8 Jul 2001 14:48:14 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx05.mrf.mail.rcn.net with esmtp (Exim 3.31 #2) id 15JJbJ-00042h-00 for marc.zeitlin@rcn.com; Sun, 08 Jul 2001 14:48:13 -0400 Received: from twc2.betaweb.com (majordomo@ns.betaweb.com [216.231.140.250]) by alum.mit.edu (8.9.3/8.9.2) with ESMTP id OAA23952; Sun, 8 Jul 2001 14:48:12 -0400 (EDT) Received: (from majordomo@localhost) by twc2.betaweb.com (8.9.3/8.9.3) id GAA22615 for cozy_builders-list; Sun, 8 Jul 2001 06:48:27 -0400 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@canard.com using -f Received: from mta5.rcsntx.swbell.net (mta5.rcsntx.swbell.net [151.164.30.29]) by twc2.betaweb.com (8.9.3/8.9.3) with ESMTP id GAA22609 for ; Sun, 8 Jul 2001 06:46:07 -0400 Received: from swbell.net ([64.123.58.75]) by mta5.rcsntx.swbell.net (Sun Internet Mail Server sims.3.5.2000.03.23.18.03.p10) with ESMTP id <0GG600B1D3NOEK@mta5.rcsntx.swbell.net> for cozy_builders@canard.com; Sun, 8 Jul 2001 13:35:49 -0500 (CDT) Date: Sun, 08 Jul 2001 13:36:39 -0500 From: David Domeier Subject: Re: COZY: idiot-proof "safety latch" To: Bob Bittner Cc: cozy_builders@canard.com Message-id: <3B48A837.55CE827B@swbell.net> MIME-version: 1.0 X-Mailer: Mozilla 4.75 (Macintosh; U; PPC) Content-type: text/plain; charset=us-ascii Content-transfer-encoding: 7bit X-Accept-Language: en,pdf References: Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: David Domeier Bob, I've been studying your drawing and have a few questions. When SH-1 is moved aft, the drawing shows the top of the part rotating above canopy part C8. This can not happen because the top of SH-1 should be inside C8 and when it goes up it contacts the horizontal part of C8 and the canopy will begin to open. Have you changed the orientation of C8? What is the function of SH-2? I just completed a three day trip to Minnesota in MKIV N10CZ. Flight time was 2:40 going and 2:20 coming back, plenty of time to look at and think about the latch system. The canopy did not open on either flight (as it hasn't on some 400 previous flights in this airplane). How come? As simplistic as it sounds, if C1-L (canopy latch handle) is seated in C9 hole, it is virtually impossible for the canopy to open. As I view the Bittner system, the same applies. If SH-1 is engaged by Sh-4, it is virtually impossible for the canopy to open. The Bittner system is not idiot proof because the same guy who does not seat C1-L in C9 hole does not have to engage SH-1 in Sh-4 before take off. The canopy will pop up to SC-1 (safety catch) limits in either case. The number of times the canopy has opened in flight on canard airplanes in the past 25 years is exaggerated. Many more people have bit the dust hot dogging than with the canopy open in-flight. The Bob Bittner conversion will not change pilot habits (which is the real problem). We need to talk about changing attitudes not changing systems to accommodate attitudes that can get us into trouble. Safe flight presumes a certain amount of discipline (using a checklist) and a respect for the old saying about how unforgiving carelessness, incapacity, or neglect can be. dd Cozy MKIV N10CZ From ???@??? Sun Jul 08 22:58:05 2001 Return-Path: Received: from mx05.mrf.mail.rcn.net ([207.172.4.54]) by mta05.mrf.mail.rcn.net (InterMail vM.4.01.03.23 201-229-121-123-20010418) with ESMTP id <20010709000728.LCHF29110.mta05.mrf.mail.rcn.net@mx05.mrf.mail.rcn.net> for ; Sun, 8 Jul 2001 20:07:28 -0400 Received: from alum.mit.edu ([18.7.21.81]) by mx05.mrf.mail.rcn.net with esmtp (Exim 3.31 #2) id 15JOaG-0006sP-00 for marc.zeitlin@rcn.com; Sun, 08 Jul 2001 20:07:28 -0400 Received: from twc2.betaweb.com (majordomo@ns.betaweb.com [216.231.140.250]) by alum.mit.edu (8.9.3/8.9.2) with ESMTP id UAA19129; Sun, 8 Jul 2001 20:07:22 -0400 (EDT) Received: (from majordomo@localhost) by twc2.betaweb.com (8.9.3/8.9.3) id MAA24648 for cozy_builders-list; Sun, 8 Jul 2001 12:09:23 -0400 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@canard.com using -f Received: from c0mailgw07.prontomail.com (mailgw.prontomail.com [216.163.180.10]) by twc2.betaweb.com (8.9.3/8.9.3) with ESMTP id MAA24642 for ; Sun, 8 Jul 2001 12:07:03 -0400 Received: by c0mailgw07.prontomail.com (NPlex 5.5.029) id 3B3DA1720022D526 for cozy_builders@canard.com; Sun, 8 Jul 2001 16:54:17 -0700 Received: from 148.71.188.254 by SmtpServer for ; Sun, 08 Jul 2001 23:54:15 +0000 Message-ID: <3B48F3B7.4394EC88@starband.net> Date: Sun, 08 Jul 2001 19:58:47 -0400 From: Jim Sower X-Mailer: Mozilla 4.77 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 CC: cozy_builders@canard.com Subject: Re: COZY: idiot-proof "safety latch" References: <3B48A837.55CE827B@swbell.net> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-cozy_builders@canard.com Precedence: bulk Reply-To: Jim Sower David, <... conversion will not change pilot habits (which is the real problem). ...> Granted. But pilot habits being the problem cannot be the solution. The solution is to increase as much as is practical the number of mistakes that have to be strung together before an failure occurrs. With the plans latch and no alarm system, one single mistake will lead to a canopy unlatched or open on takeoff. With the plans alarm, two mistakes (defeating the alarm and fortetting to check canopy closed and locked) will do it. With an alarm with a defeat feature that 'times out', it will take more than two. A dedicated alarm system (unlike the 3-function plans system) could be made that would render 'inadvertant' takeoff with canopy unlatched virutally impossible. Bittner system seems mostly an attempt to make a more reliable safety catch but doesn't do much new to prevent the pilot from taking off with canopy unlocked. Good for damage control - keeps an incident from becoming an accident - but doesn't do much to prevent the incident. My preference would be a dedicated alarm that allows enough power to taxi with canopy unlatched/open but will activate at higher power settings (say 1200-1500 RPM or mag check power) and can't be defeated. Moving the 'Lock Canopy' checklist item to mag check time will allow one to check the alarm every flight as well as give him no peace until the canopy is truly locked. <... Many more people have bit the dust hot dogging ...> Granted. Add to that fuel management and inadvertant IMC and poor preflight and nosewheel up and flying with a known problem and a loooooonng list of other stuff. The object of the exercise is to take distractions out of the loop as much as possible. Requie as much as possible that the pilot do something DELIBERATELY stooopid as a prerequisite to an incident. Just a theory .... Jim S. David Domeier wrote: > Bob, > > I've been studying your drawing and have a few questions. > > When SH-1 is moved aft, the drawing shows the top of the part rotating > above canopy part C8. This can not happen because the top of SH-1 > should be inside C8 and when it goes up it contacts the horizontal part > of C8 and the canopy will begin to open. Have you changed the > orientation of C8? > > What is the function of SH-2? > > I just completed a three day trip to Minnesota in MKIV N10CZ. Flight > time was 2:40 going and 2:20 coming back, plenty of time to look at and > think about the latch system. > > The canopy did not open on either flight (as it hasn't on some 400 > previous flights in this airplane). How come? > > As simplistic as it sounds, if C1-L (canopy latch handle) is seated in > C9 hole, it is virtually impossible for the canopy to open. > > As I view the Bittner system, the same applies. If SH-1 is engaged by > Sh-4, it is virtually impossible for the canopy to open. > > The Bittner system is not idiot proof because the same guy who does not > seat C1-L in C9 hole does not have to engage SH-1 in Sh-4 before take > off. The canopy will pop up to SC-1 (safety catch) limits in either case. > > The number of times the canopy has opened in flight on canard airplanes > in the past 25 years is exaggerated. Many more people have bit the dust > hot dogging than with the canopy open in-flight. > > The Bob Bittner conversion will not change pilot habits (which is the > real problem). We need to talk about changing attitudes not changing > systems to accommodate attitudes that can get us into trouble. Safe > flight presumes a certain amount of discipline (using a checklist) and a > respect for the old saying about how unforgiving carelessness, > incapacity, or neglect can be. > > dd > Cozy MKIV N10CZ Subject: COZY: Shark latch system From: "Bob Bittner" Date: Mon, 9 Jul 2001 10:30:16 -0500 Thanks, everyone, for the compliments, and for the criticism. Eventually, we'll get this problem solved. It appears it's up to us builders to do so. For the most part, my offerring was put out there to get ideas flowing... so far, so good. Yes, the canopy can rest on top of SH-1 and SH-2, as on the plans system. In this case, though, the thicker SH-1 and SH-2 hold the canopy open nearly an inch, which is quite noticeable. >When SH-1 is moved aft, the drawing shows the top of the part rotating >above canopy part C8. This can not happen because the top of SH-1 >should be inside C8 and when it goes up it contacts the horizontal part >of C8 and the canopy will begin to open. Have you changed the >orientation of C8? As SH-1 and SH-2 rotate open, they push up on C8 and the canopy opens. C8 is not moved, nor are any of the other mounting holes. >As simplistic as it sounds, if C1-L (canopy latch handle) is seated in >C9 hole, it is virtually impossible for the canopy to open. Sorta... If, when C9 nicely secures C1-L, the canopy is completely closed, then the problem is that the C1-L has to pull the canopy "tighter than closed" to get the AN525 screw into C9. If C9 isn't regularly bent to spring against C1-L, or C9 isn't adjusted exactly right, C1-L can pop out of C9... the plans system fails, and hopefully, the safety catch catches. I will agree, though, that a bunch of time flying with ANY latch system is worth more than engineering and speculation. (which is all I can offer at this point) However, looking down the line of EZs at OSH, many have replaced C9 with a secure latching system, so maybe more flight time reveals a need to replace C9. ??? >The Bittner system is not idiot proof because the same guy who does not >seat C1-L in C9 hole does not have to engage SH-1 in Sh-4 before take >off. The canopy will pop up to SC-1 (safety catch) limits in either case. True, "idiot-proof" isn't really correct. Whenever a true idiot gets in an airplane, let's just all hope he doesn't take anyone with him.. But, as long as the canopy is not resting on top of SH-1 and SH-2s, the hooks provided therein will catch, in case the spotty performance of the safety catch reveals itself. Part of my thought process, to get the idea blessed by Nat, was to make it as much better than the plans system as possible, while making it only slightly different. This doesn't have to get too complex. I fabricated and installed the shark latch lock (C9 replacement) over the weekend. I didn't yet replace C1-L and C2-L. It's amazing mow much more securely the canopy is held in place now. Look for a photo later today. Thanks for the tip about springs. I'll see if I can work in a compression spring instead. re: more bite it from hotdogging, etc. True. Again, I don't really care if anyone has ever augered in because the canopy opens. It's just a damn inconvenience, and a serious hit to the confidence in your workmanship, when the plans system fails. I'd love to see any photos or drawings of others' latch systems posted somewhere. Thanks Bob From: "Nat Puffer" Subject: COZY: spring steel safety catch Date: Thu, 2 Aug 2001 13:27:13 -0500 Builders, Jack Wilhelmson sent us his spring steel safety catch and we just finished installing it. It is the best thing since sliced bread! I can bend it back quite a ways without it taking a set. Our problem is that so many people ask to sit in our airplane and try it out for size. They always want to close the canopy to check out the head room. Half the time they try to open the canopy by themselves and bend the safety catch way back before I can stop them. The stainless catch will take a set, so I always have to check it after someone bends it way back. This isn't a problem for me the rest of the year when I am the only one sitting in the airplane, so for me, this is a BIGGGG improvement! We will recommend the spring steel safety catch over the one shown in the plans (which was designed by Burt). Jack said he will charge $15. He said he has already sent out 15, and if the orders keep up, he will have to make some special dies. Regards, Nat