Date: Mon, 18 Oct 1999 23:19:23 -0400 From: "Ryszard J. Zadow" Subject: COZY: [c-a] AOA and the Canard.... Message text written by David Domeier Without trying to offend anyone let me throw in two cents... The angle of attack an airfoil stalls at is always the same. The airspeed will differ based on gross weight, but the stall aoa never changes, upside down, rightside up whichever way you put it. That's why the Navy uses AOA to land on the ship. We calculated a referance airspeed to back up the AOA gauge. The airspeed would be different for "on-speed" (Amber Donut). Heavier aircraft, faster approach speed. Lighter aircraft, slower speed. That's also why we dumped gas down to a certain limit, to make us lighter, to be able to land at a speed that was an optimum between what the arresting gear could handle, our max carrier landing weight and enough gas to make a few passes and still divert. But the real point here is stall AOA never changes. If you had a good AOA gauge set up to show a certain margin above stall on approach, you would see that speed changes with different loading. Ryszard From: "Nat Puffer" Subject: COZY: Angle of attack Date: Mon, 18 Oct 1999 16:39:13 -0500 Builders, When we did our aft c.g. tests, we started out without lower winglets and too much canard span. We had a 135 weight that we could move electrically from the nose to the firewall to change the c.g. from 1 inch forward of our forward limit to 1.3 inches aft of our aft limit. We had a vane type angle of attack indicator. We found that at aft c.g., as we slowed down, the speed would hesitate with the angle of attack indicating about 14 degrees, and then suddenly the back end would drop (main wing stall), the angle of attack would shoot up, and the airspeed would drop. Without lower winglets, the airplane would tend to flip. With lower winglets, the main wing wouldn't stall so easily, and when it stalled it was wings level. We would recover from a main wing stall at aft c.g. simply by dumping the nose before we lost forward speed. We never had to recover by moving the weight forward. Only once did we fail to recover soon enough, and lost about 5000 ft before recovery. After installing the lower winglets, we gained about 1/2 inch of additional c.g. range before the main wing would stall, wings level. After shortening the canard span 3 inches each side (per 1st edition plans. 2nd edition plans were changed to show the shortened canard), the main wing did not stall anywhere in the approved c.g. range, including a c.g. aft of the aft limit by 1.2 inches. After making these changes, the main wing would not stall slowing down in level flight and pulling the nose up to 14 degrees angle of attack. At 14 degrees, the canard would stall at 60 kts at forward c.g., and at 50 kts. at aft c.g. Canard stall was really a non-event, at least at 11,000 ft, or any altitude above the ground. The canard falls through the horizon, you pick up a little speed and the canard flies again, without losing much if any altitude. At 5 ft above the runway, having the canard fall through the horizon might give the nosewheel a little jolt. But the rule of thumb is to fly the approach about 20 kts above the stall or minimum flying speed. So we come over the fence at 80 kts and slow down as we flare onto the runway. At this point my eyes are glued on the runway, not on the instrument panel, so I don't know how an AOA indicator would be of help. I would not encourage pilots to be watching the instrument panel as they were flaring for a landing. My 2c worth. Nat Date: Wed, 20 Oct 1999 16:54:31 -0400 From: Lynda Frantz Subject: COZY: Angle-of-Attack on Canards I was forwarded comments from your builders group and found them all interesting. Newman, Domeier, Zeitlin, Sower and Ashton all make good points. As the only manufacturer of AOA with out any probes or protrusions, I would like to clarify some of the issues. AOA is best used at maneuvering speeds where it is the most accurate and the IAS is the least accurate. Stall warning, best engine out glide (L/Dmax), best approach AOA, Vx and more are examples of performance points where IAS will not help but AOA will. Our family of AOA instruments are calibrated to your specific aircraft in flight using a zero "G" maneuver and a slow flight maneuver. The zero "G" maneuver determines the AOA reference point where the aircraft creates no lift thus no induced drag. This is what we call zero angle from zero lift. On our Professional AOA when you see 000 on the display, you know you are at zero degrees angle from zero lift, that the airfoil is creating no lift or induced drag, and will fly at any speed without stalling right on down to 1 knot. Remember that we can fly airfoils down to 1 knot without them stalling provided the AOA is low enough. Conversely, we can stall an airfoil at any speed with the AOA at the critical AOA. The purpose of the slow flight calibration maneuver is to establish the AOA where you want the stall warner to activate. We recommend that this be set at 15% above the stalling speed which is equivalent to 23% below the stalling angle. When you reach or exceed this warning angle in flight, the aural voice activates "angle angle push". The other common misconception is the significance of where the pressure taps should be located. Generally it does not matter provided the taps are located on a lifting body that is looking at undisturbed air. We patented this concept. The canard is mechanically attached to the fuselage and the main wing is mechanically attached to the fuselage and generally the AOA of the canard and the AOA of the main wing vary by a fixed constant. Thus it does not matter if the AOA ports are located on the main wing, the canard, on a probe or even on the nose (provided the nose is an airfoil shape). The prefered location is however on the main wing because it is easier to install there. But remember the pressure taps must be located in undisturbed air ie outboard of the wash from the canard. Hope that this clarifies some of the discussion. Visit our web at www.angleofattack.com James B. Frantz President Proprietary Software Systems, Inc. Date: Tue, 19 Oct 1999 13:51:06 -0700 From: Ed Neilander Subject: COZY: AOA To all: After reading the posts and not remembering where this started i noticed that no one seems to have asked the question as to having had the pitot static system checked by a certified shop. wouldn't this fast airspeed indicator been found early on and been calibrated to be correct thus making all of this moot? Ed Neilander From: "Capps Family" Subject: COZY: AOA : CG and AC distance Date: Mon, 18 Oct 1999 20:04:56 -0500 Nat wrote; "Builders, When we did our aft c.g. tests, we started out without lower winglets and too much canard span. We had a 135 weight that we could move electrically from the nose to the firewall to change the c.g. from 1 inch forward of our forward limit to 1.3 inches aft of our aft limit. We had a vane type angle of attack indicator. We found that at aft c.g., " QUESTION: During the tests, what was the distance(s) calculated for the c.g. and a.c? What is the distance between the c.g. and a.c? Larry Larry A. Capps #829 cappsfan@ameritech.net Naperville, IL From: "dewayne morgan" Subject: COZY: aoa and stall warnings Date: Mon, 18 Oct 1999 20:04:04 -0400 I ran across kids toy whistle one time i thought was broken. After further investigation, I found out that it only made a sound at a certain angle at which the air went across it, regardless of velocity (to the extent that i tested it). I often wondered if this could be could be used in ultralight/ experimentals if affixed on the aircraft as an inexpensive way to pre-warn to a stall. (if it could even be heard) just a thought (unless someone makes, millions then i want royalties or a completed cozy ;) ) dewayne Date: Sun, 17 Oct 1999 22:23:26 -0500 From: David Domeier Subject: COZY: AOA and the Canard.... Jim, re "Fighters and airliners get *seriously* cocked up on final approach. Long-EZs and Cozys *do not*. The AOA range between, say, 75 and 80 or 85 KIAS (at a given weight) I would guess to be perhaps a couple of degrees tops....Wasn't this whole AOA thread precipitated by someone who 'ran out of peanut butter at the ramp' because his ASI was displaying MPH labeled as KTS? " I was the guy who ran out of peanut butter, but it wasn't on the ramp, it was over the fence about 30 feet above the cement. Aside from the mph vrs knots issue, and AOA, another issue, perhaps more crucial, is the stall speed of the canard relative to cg. When I flight tested this machine at the aft cg limit, the canard quit flying at about 55 knots. When the event which precipitated this string occurred, the cg was near the forward limit and the canard quit flying at about 68 knots. (gw wasn't the same but close enough for sake of discussion) It seems clear that at a given gross weight, the deciding approach speed in these airplanes has to be based on the stall speed of the canard, not the wing, and the since cg effects the canard stall speed, a simple AOA number , which is always based on gross weight as far as I know, won't cut it. AOA, in these airplanes, has to include a factor for center of gravity (and gross weight) and the cost of such an electronic determination is probably more than most of us want to endure. A better solution is to know the gw, cg, and fly an appropriate approach speed based on flight testing - with 2 ASI's if accurate airspeed is worrisome. I would be satisfied with one ASI if I could get it properly calibrated so as not to have to factor in some gross instrument error. dd From: MARC_ZEITLIN@HP-Andover-om1.om.hp.com Date: Mon, 18 Oct 1999 11:23:55 -0400 Subject: COZY: AOA and the Canard.... Dave Domeier wrote: > ..... since cg effects the canard stall speed,........ As it will on all aircraft, not just canards. > ....... a > simple AOA number , which is always based on gross weight as far as I > know, won't cut it. Actually, the AOA for stall is NOT a function of weight, although the SPEED is. You are correct, though, that the CANARD is the wing that would have to have the AOA measured - not the main wing. With some of the new electronic AOA gauges (NOT a "vane type") this should not be a problem. If you had an AOA gauge for the canard, it would tell you categorically when you were close to stall (unless the fact that the canard has a variable flap [the elevator] on it changes the equation, which I haven't spent enough time thinking about to determine completely - maybe some of the more aerodynamically active engineers can comment). > ..... and the cost of such an > electronic determination is probably more than most of us want to > endure. That may very well be the case, althought the $800 or so for an electronic AOA gauge is not completely out of line, in comparison with other aircraft instruments. -- Marc J. Zeitlin marcz@ultranet.com http://cozy.canard.com Non Impediti Ratione Cognitanis (C&C) Date: Mon, 18 Oct 1999 12:37:41 -0500 From: David Domeier Subject: Re: COZY: AOA and the Canard.... Marc, re "Actually, the AOA for stall is NOT a function of weight, although the SPEED is." You of course are absolutly correct. I was thinking about the post after I sent it and I knew that part was not right, it made no sense to me, either. dd Date: Mon, 18 Oct 1999 13:47:54 -0500 From: David Domeier Subject: COZY: AOA and the Canard.... Jim, I created confusion yesterday because sometimes I do not write clearly what I thinking, or my thinking is not very clear.... there was some of each in that post. The point I was trying to make (and didn't) is that in a canard airplane where both surfaces create positive lift, the approach speed to maintain Vso plus 30% with the cg at aft limit is less than if the cg were at the forward limit because the canard was carrying less of the flight load and would maintain flight at the optimal AOA at a lower airspeed. The post also created the impression with some readers I did not understand AOA. I do, or least I should after being around airplanes all my life. The canard stalls at a given AOA, probably around 12°, and the wing around 20°. A canard AOA indicator would tell you when departing the optimal angle for the approach. So it would work after all. I always thought it would, but somehow yesterday I went off on a tangent of thinking that doesn't make much sense today, especially to me who did the thinking. Sorry for the confusion, guys. dd From: MARC_ZEITLIN@HP-Andover-om1.om.hp.com Date: Tue, 19 Oct 1999 08:12:43 -0400 Subject: COZY: AOA and the Canard.... Kent Ashton wrote: > Agree with all you said but it occurs to me that often times > the canard never really stalls...... > ...... If it can't develop X pounds, the nose will fall, even > though the airfoil isn't stalled. Thus an AOA indicator on the canard isn't > always useful. > Where is the flaw in my thinking? The flaw is that you've just defined a stall, and then said it's not called a stall :-). The canard will continue to produce more lift as more elevator is added and the AOA increases. When it reaches the point at which the lift begins to decrease as AOA increases, that's the __definition__ of the stall. You never "ask" the canard to develop "X" pounds of lift - all you can ever do is set an AOA with the elevator position. Either that will be stalled or it won't, but if it isn't, the AOA won't decrease on it's own. The whole point in this discussion is that if Dave Domeier had an AOA indicator on his canard during the "hard landing" flight, he would have known that he was much closer to stalling the canard during his approach than he ever had been before, and he wouldn't have tried to lower his speed more. He could have flown the AOA rather than the airspeed, and judged his flare height by AOA rather than airspeed. -- Marc J. Zeitlin marcz@ultranet.com http://cozy.canard.com Non Impediti Ratione Cognitanis (C&C) From: "Todd Carrico" Subject: COZY: Canard Stall.. was AOA Date: Mon, 18 Oct 1999 13:26:33 PDT All this hashing and rehashing got me to thinking: There has to be a cheaper way to warn of an impending canard stall. What about the stall horn? What is involved with the design and application of one the the canard. ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com Date: Mon, 18 Oct 1999 19:18:56 -0400 From: Jim Sower Subject: Re: COZY: Canard Stall.. was AOA I don't want to get too radical here, but is there some compelling reason why we can't Test the airplane at various weights; Practice landing at all these heavier weights, Know what we weigh when we set up to land and Remember what we learned testing??  For my own part, I practiced some no-ASI approaches (using pitch buck as a speed cue) and was surprised how well it worked.  Wouldn't want to do it at night or on a real gusty day, but I reckon I could if I had to.  Kind of wondering what I would do with a canard-impending-stall-horn if I had one.
Just a theory ;-)         Jim S.

Todd Carrico wrote:

All this hashing and rehashing got me to thinking:
There has to be a cheaper way to warn of an impending canard stall.  What
about the stall horn?  What is involved with the design and application of
one the the canard.

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com

From ???@??? Tue Oct 19 09:48:47 1999 Return-Path: owner-cozy_builders@betaweb.com Received: from twc2.betaweb.com (majordomo@betaweb.com [206.43.209.18]) by acestes-fe0.ultra.net (8.8.8/ult/n20340/mtc.v2) with ESMTP id AAA21092 for ; Tue, 19 Oct 1999 00:59:07 -0400 (EDT) Received: (from majordomo@localhost) by twc2.betaweb.com (8.8.5/8.8.5) id WAA06078 for cozy_builders-list; Mon, 18 Oct 1999 22:57:30 -0400 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@betaweb.com using -f Received: from popserv2.vnet.net (popserv2.vnet.net [166.82.1.30]) by twc2.betaweb.com (8.8.5/8.8.5) with ESMTP id WAA06072 for ; Mon, 18 Oct 1999 22:57:26 -0400 Received: from vnet.net (ppp-conc-86.vnet.net [166.82.238.86]) by popserv2.vnet.net (8.9.1a/8.9.1) with ESMTP id WAA26338; Mon, 18 Oct 1999 22:53:53 -0400 (EDT) Message-ID: <380BDD9A.150C8B3@vnet.net> Date: Mon, 18 Oct 1999 22:55:49 -0400 From: kent ashton X-Mailer: Mozilla 4.03 (Macintosh; U; 68K) MIME-Version: 1.0 To: Todd Carrico CC: cozy_builders@canard.com Subject: Re: COZY: Canard Stall.. was AOA References: <19991018202633.13174.qmail@hotmail.com> Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-cozy_builders@betaweb.com Precedence: bulk Reply-To: kent ashton X-UIDL: 31c7d1efc0aea45abcb61f1ec90651f3 When your stick is bumping against the aft stop, you are at the flying limit of the canard. The airfoil may not be stalled, but it isn't generating enough lift to hold the nose up. --Kent A. Todd Carrico wrote: > > All this hashing and rehashing got me to thinking: > There has to be a cheaper way to warn of an impending canard stall. What > about the stall horn? What is involved with the design and application of > one the the canard. Date: Mon, 18 Oct 1999 09:52:57 -0400 From: Jim Sower Subject: COZY: Re: AOA and the Canard.... DD, <... and the since cg effects the canard stall speed, a simple AOA number ...> This is the part where I am going to need the documentation I alluded to. My best information (up until now) is that an airfoil stalls at a certain angle of attack. Airfoil has no way in the world of knowing how much anything weighs, or how the weight is distributed. It knows about angle of attack, velocity, air density and (marginally) Reynolds number and that's it. My guess is that in light of the fact that canard stall drives minimum airspeed the main wing and what it is doing is irrelevant here. Now, the canard is a *FAT* straight airfoil so it's going to stall relatively abruptly. It has a relatively small range of AOA from lift increases with AOA (flying) to lift decreasing with AOA (stalled). But even a small range is still a range. What we have at forward CG is canard loaded a lot more than the main wing, so to achieve a certain pitch attitude you need a lot of up elevator. Now, with all that elevator deflection, you have a *different* airfoil, with *different* (read lower?) stall AOA. Aft CG allows you to achieve the same pitch attitude with *much* less elevator deflection. You are now 'closer' to the airfoil you thought you were studying all along. Airliners and fighters get to calibrate AOA indicators to a single airfoil - flaps, slats, etc. fully deployed (fighters I flew stalled at *way* different AOA when clean). Canard airplanes with CG range have to have AOA calibrated for the *airfoil range* encountered in landing. It's not going to happen. NASA doesn't build, and DOD doesn't fund elaborate (and marginally beneficial) accessories for Long-EZs and Cozys. Just a theory, Jim S. David Domeier wrote: > Jim, > > re "Fighters and airliners get *seriously* cocked up on final > approach. Long-EZs and > Cozys *do not*. The AOA range between, say, 75 and 80 or 85 KIAS (at a > given weight) I would guess to be perhaps a couple of degrees > tops....Wasn't this whole AOA thread precipitated by someone who 'ran > out of peanut butter at the ramp' because his ASI was displaying MPH > labeled as KTS? " > > I was the guy who ran out of peanut butter, but it wasn't on the > ramp, it was over the fence about 30 feet above the cement. > > Aside from the mph vrs knots issue, and AOA, another issue, perhaps > more crucial, is the stall speed of the canard relative to cg. > > When I flight tested this machine at the aft cg limit, the canard > quit flying at about 55 knots. When the event which precipitated this > string occurred, the cg was near the forward limit and the canard quit > flying at about 68 knots. (gw wasn't the same but close enough for sake > of discussion) > > It seems clear that at a given gross weight, the deciding approach > speed in these airplanes has to be based on the stall speed of the > canard, not the wing, and the since cg effects the canard stall speed, a > simple AOA number , which is always based on gross weight as far as I > know, won't cut it. AOA, in these airplanes, has to include a factor > for center of gravity (and gross weight) and the cost of such an > electronic determination is probably more than most of us want to > endure. > > A better solution is to know the gw, cg, and fly an appropriate > approach speed based on flight testing - with 2 ASI's if accurate > airspeed is worrisome. I would be satisfied with one ASI if I could get > it properly calibrated so as not to have to factor in some gross > instrument error. > > dd Date: Mon, 18 Oct 1999 12:46:31 -0400 From: "Johnson, Phillip" Subject: COZY: RE: AOA and the Canard.... The AOA meter is not going to afford you protection against canard stall, (which is related to weight & balance) but it will afford you protection against main wing stall since the geometry of this surface does not change as a function of W&B etc. I considered it ,after seeing it at Oshkosh, for this very reason. Main wing stall is deadly, Canard stall at the wrong time is less likely to result in a fatality (notice I say less likely). Is the instrument worth $800? Probably not a bad investment and has got to be more valuable than some of those other do dads that people seem to put in their aircraft. The biggest threat from the AOA meter is from the belief that the instrument provides information on the stall characteristics of the Canard. Phillip Johnson Date: Mon, 18 Oct 1999 22:44:45 -0400 From: kent ashton Subject: Re: COZY: Re: AOA and the Canard.... Jim Sower wrote: [snip some good discussion of canard stall] > Now, the > canard is a *FAT* straight airfoil so it's going to stall relatively > abruptly Agree with all you said but it occurs to me that often times the canard never really stalls. Since it is so highly loaded, it sometimes reaches a point where it cannot generate sufficient lift, even with full down elevator, to keep the nose up. The canard has to generate X pounds of lift to balance the CG and wing lift. If it can't develop X pounds, the nose will fall, even though the airfoil isn't stalled. Thus an AOA indicator on the canard isn't always useful. Where is the flaw in my thinking? --Kent A. Date: Mon, 18 Oct 1999 23:05:56 -0400 From: kent ashton Subject: Re: COZY: RE: AOA and the Canard.... My Cozy requires 20 lbs of lead shot way up in the nose to be in a flyable CG when solo. One time I got sloppy and threw it up in the footwell as "good enough". On landing, I was thinking, wow I really do have some nice pitch authority here and I'm going to get the world's slowest canard touchdown. I was flaring and flaring just a foot or so above the runway when all of a sudden the bottom fell out of the airplane like you had turned off the lift switch. Cracked my wheel pants and jarred my fillings. I think what happened is that I got a wing stall, fortunately just a couple of feet off the runway. I say this embarassing story to make the point that I think if you ever see a wing stall in a canard airplane in flight, you can kiss your ass goodbye. Thus an AOA gauge on the wing is a "hi, you are now going to die" indicator. Kent A. Johnson, Phillip wrote: > > The AOA meter is not going to afford you protection against canard > stall, (which is related to weight & balance) but it will afford you > protection against main wing stallP From: "DL Davis" Subject: RE: COZY: RE: AOA and the Canard.... Date: Tue, 19 Oct 1999 06:51:53 -0400 > -----Original Message----- > From: owner-cozy_builders@betaweb.com > [mailto:owner-cozy_builders@betaweb.com]On Behalf Of kent ashton > I think if you ever see a wing stall in a canard airplane in flight, you can > kiss your ass goodbye. Thus an AOA gauge on the wing is a "hi, > you are now > going to die" indicator. > > Kent A. I don't think so. You should be able to recover from a main wing stall in a canard airplane, just as you would in a conventional airplane, IF it is balanced properly. There seems to be a persistent myth that a main wing stall causes a so called "deep stall" that is unrecoverable in a canard. If the CG is in the correct range, you can very easily recover a main wing stall in a canard. If the CG is too far aft, you won't... just like a conventional airplane that can develop an unrecoverable flat spin with the same poor aft cg. Perhaps the reason this myth persists is that we hear so much about the deep stall accidents a few years ago (all caused by improper CG), and we don't often hear about main wing stall recoveries because most folks never stall their main wings. Well I can tell you that I have stalled my main wing and it was nothing but a piece of cake to recover. At 5000 ft, I flew the airplane straight up until it ran out of airspeed, zero airspeed. The airplane fell back on its tail and then the nose simply fell from pointing straight up, to pointing straight down. The airspeed built up QUICKLY and I simply started flying again. I know there are lots of others that have experienced a main wing stall and found it to be no big deal. Personally, I wouldn't recommend people do it for the helluva it. But for heavens sake if you ever do find yourself in a main wing stall, don't kiss your ass goodbye, just fly the airplane. Dewey Davis Cozy N24DL From: "Nat Puffer" Subject: Re: COZY: RE: AOA and the Canard.... Date: Tue, 19 Oct 1999 12:44:14 -0500 ---------- > From: Bulent Aliev > Cc: 'Cozy Mailing List' > Subject: Re: COZY: RE: AOA and the Canard.... > Date: Tuesday, October 19, 1999 2:59 PM > > >There > are few people that have survived deep stall and are still around. > Bulent > Builders, I object to these scare tactics! The Velocity had a main wing stall problem initially. There were 3 Velocity main wing stalls, and all 3 pilots survived. After that, Danny Maier did "trailer" tests on the ground and defined the problem. He first installed wing cuffs, and later lengthened the chord on the wings. He left the lower winglets in place. I don't know what the Velocity record has been since. We did our aft c.g. flight testing before any builders were flying; determined that the lower winglets were necessary, and that the canard span had to be shortened. After these changes, we were not able to stall the main wing on our Mark IV, and to the best of my knowlege, no plans-built Cozy Mark IV operating within the approved c.g. range has had a main wing stall. Let's stop trying to scare builders. We are told the Cozy safety record is twice as good as Cessna's Regards, Nat From: "Bill James" Subject: COZY: Re: [c-a] Re: AOA and the Canard.... Date: Mon, 18 Oct 1999 19:47:50 PDT From: Jim Sower "... and the since cg effects the canard stall speed, a simple AOA number ... Now, the canard is a FAT straight airfoil so it's going to stall relatively abruptly. It has a relatively small range of AOA from lift increases with AOA (flying) to lift decreasing with AOA (stalled)...." Jim-- And for those of us fascinated by this AOA thread-- Is anyone else's mind being blown by the exercise of contemplating that the canard 'lifts' more as airspeed 'increases'? Klaus, in his OSH forum, made several interesting comments about climbing at 600 fpm at low AND high speeds. The 'high speed' was about 190 mph, if I remember (out of 240 mph). Ever hear the RACE guys talk about getting cramps in their hand or arm and having to switch hands to push forward on the stick after 20 or 30 minutes? Was the canard optimized for about 165 mph? ...that the canard is LESS efficient at low airspeeds-- therefor the aircraft itself is less efficient overall in climb at those lower airspeeds?... ...that at cruise, if the nose lowers a little, that, as the speed increases, the nose lifts back up?... ...that during HIGH altitude cruise, the plane will climb "pretty good" at normal cruise speed if the nose lifts a little, but if the nose is purposefully raised to the normal best climb speed, the lift fades at that lower speed?. Ah well, Probably isn't significant. / -|-<<<<<<<<<<<<<<<<< Bill <<<<<<<<<<<<<<<<:) \ ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com Date: Tue, 19 Oct 1999 20:21:34 +0000 From: Wayne Lanza Subject: COZY: Re:Deep Stall Stuff Hello to the Group, I normally don't get into the stronger discussions but I must comment on this topic. Listen to what Nat is saying, it is based on FACTUAL numbers! I know the Velocity well, (designer) Dan Maher and I have been friends for many years and I followed all of the testing very closely. Nat, too, was made aware of those proceedings and no doubt considered Dan's results when he did his own in-depth deep stall testing. Here is the bottom line of all the testing done on the Velocity and Cozy... The Cozy remains, statistically, one of the safest experimental designs, EVER! The deep stall issues with Velocity are nonexistent, if you build it per plans. It seems that too many Velocity builders had better ideas than the designers numbers would allow for, unfortunately they didn't know much about aero- dynamics, couldn't figure weight & balance, etc... The fact that they didn't all perish proving their ideas is a testament to the design's integrity. The changes that D.Maher made to his design were to mostly to advert the negatives that the 'more creative' builders introduced when they made 'improvements'. The experienced guys will all tell you - "It ain't broke, so don't fix it" Take Care & Safe Flying to All, Wayne Lanza From ???@??? Wed Oct 20 08:14:30 1999 Return-Path: owner-cozy_builders@betaweb.com Received: from twc2.betaweb.com (majordomo@betaweb.com [206.43.209.18]) by acestes-fe0.ultra.net (8.8.8/ult/n20340/mtc.v2) with ESMTP id OAA17098 for ; Wed, 20 Oct 1999 14:20:13 -0400 (EDT) Received: (from majordomo@localhost) by twc2.betaweb.com (8.8.5/8.8.5) id NAA11650 for cozy_builders-list; Wed, 20 Oct 1999 13:31:40 -0400 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@betaweb.com using -f Received: from imo16.mx.aol.com (imo16.mx.aol.com [198.81.17.6]) by twc2.betaweb.com (8.8.5/8.8.5) with ESMTP id NAA11644 for ; Wed, 20 Oct 1999 13:31:37 -0400 From: ZeroGCorp1@aol.com Received: from ZeroGCorp1@aol.com by imo16.mx.aol.com (mail_out_v23.6.) id oZEWa12219 (4212); Wed, 20 Oct 1999 13:27:20 -0400 (EDT) Message-ID: <0.4c0b55f1.253f5578@aol.com> Date: Wed, 20 Oct 1999 13:27:20 EDT Subject: Re: COZY: Re:Deep Stall Stuff To: wlanza@iu.net, cozy_builders@canard.com MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Windows AOL sub 41 Sender: owner-cozy_builders@betaweb.com Precedence: bulk Reply-To: ZeroGCorp1@aol.com X-UIDL: 62374ed6f312c2b7daed86bb3dadb4b8 In a message dated 10/19/99 7:21:59 PM Central Daylight Time, wlanza@iu.net writes: > The experienced guys will all tell you - "It ain't broke, so don't fix it" gee, aren't we all glad Nat didn't have this attitude when Burt Rutan was finished with the longEZ...I have liked this thread, but I don't see how adding an instrument like the AOA is a bad idea. I am getting a private pilots license now and my instructor is insisting that I work with GPS. Why? it is reliable and it is today's technology. Much like VOR and Loran were improvements on the old reliable compass. Nat is taking the position that he should as a designer and as the sole person responsible for our plane. I agree that he should insist not to deviate from plans. So did Burt. IF you do deviate from plans, don't call it a cozy and don't blame Nat if you buy the farm. Innovation should not be taken lightly here. There are millions of better ideas out there waiting to be discovered. Aviation did not reach an end when the Cozy went down on paper, but if you are not willing to do the hard work done by Nat, Burt, and others, then don't be an innovator. Unfortunately this is exactly what has led Burt Rutan to the point where he must flat say, "don't build planes if you are an amateur, and don't build my planes period." I have spent a lot of time with him and it is dad that the Lawyers are sucking off yet another fine industry. That being said, I understand that the AOA does take a really safe airplane and make it safer. I think that is good in general and I will probably use one in m plane (should I ever finish ;^). Thanks to Nat and others for all the lively discssion. Be smart and follow the plans unless you are committed to proving your design. Ray Cronise rom ???@??? Thu Oct 21 10:03:20 1999 Return-Path: owner-cozy_builders@betaweb.com Received: from twc2.betaweb.com (majordomo@betaweb.com [206.43.209.18]) by acestes-fe0.ultra.net (8.8.8/ult/n20340/mtc.v2) with ESMTP id XAA17660 for ; Wed, 20 Oct 1999 23:23:19 -0400 (EDT) Received: (from majordomo@localhost) by twc2.betaweb.com (8.8.5/8.8.5) id WAA20740 for cozy_builders-list; Wed, 20 Oct 1999 22:52:43 -0400 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@betaweb.com using -f Received: from smtp1.vnet.net (smtp1.vnet.net [166.82.1.31]) by twc2.betaweb.com (8.8.5/8.8.5) with ESMTP id WAA20735 for ; Wed, 20 Oct 1999 22:52:33 -0400 Received: from lmd.vnet.net (lmd.vnet.net [166.82.1.41]) by smtp1.vnet.net (8.9.1a/8.9.1) with ESMTP id WAA19832; Wed, 20 Oct 1999 22:34:45 -0400 (EDT) Received: from popserv.vnet.net (popserv.vnet.net [166.82.1.29]) by lmd.vnet.net (8.9.3/8.9.3) with ESMTP id WAA03519; Wed, 20 Oct 1999 22:34:42 -0400 (EDT) Received: from vnet.net ([166.82.250.82]) by popserv.vnet.net (8.8.8+Sun/8.8.8) with ESMTP id WAA09011; Wed, 20 Oct 1999 22:34:37 -0400 (EDT) Message-ID: <380E618A.E46E1AC6@vnet.net> Date: Wed, 20 Oct 1999 20:43:13 -0400 From: kent ashton X-Mailer: Mozilla 4.03 (Macintosh; U; 68K) MIME-Version: 1.0 To: MARC_ZEITLIN@HP-Andover-om1.om.hp.com CC: "Cozy_Builders@canard.com" Subject: Re: COZY: AOA and the Canard.... References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-cozy_builders@betaweb.com Precedence: bulk Reply-To: kent ashton X-UIDL: 756e343ff3e28ec564c9ebcb61d724e3 Well, I might be wrong so I will have to talk louder.. In level flight, the canard has to develop X pounds of lift compared to the wing's 3X (I'm guessing at the relationship) pounds of lift, in order to support its share of the G.W. of the airplane in a level attitude. As you slow down, you have to add more down-elevator, and increase canard AOA in order to develop the same X pounds of lift. If you get to a speed where you have full down-elevator, you can no longer hold a level attitude, but you may not have reached the "stall AOA" for the canard. So the canard doesn't meet the classic definition of "stalled". At mid to aft CG, the canard on my Cozy truely does stall and unstall in the classic pitch-buck stall mode. But at forward CGs, I never see the stall/unstall mode. I reach a speed where the stick is at the aft stop and the nose begins to sink. I think this is a point where the canard has not yet reached the stall AOA but isn't producing its X pound share of lift. If I had a moveable canard that could be cranked to a higher AOA, I could generate more lift under that condition. I couldn't do that If I had reached the "stall AOA" of the airfoil. --Kent A. "Sometimes wrong, never in doubt" From ???@??? Thu Oct 21 10:03:20 1999 Return-Path: owner-cozy_builders@betaweb.com Received: from twc2.betaweb.com (majordomo@betaweb.com [206.43.209.18]) by acestes-fe0.ultra.net (8.8.8/ult/n20340/mtc.v2) with ESMTP id WAA27468 for ; Wed, 20 Oct 1999 22:56:30 -0400 (EDT) Received: (from majordomo@localhost) by twc2.betaweb.com (8.8.5/8.8.5) id WAA20077 for cozy_builders-list; Wed, 20 Oct 1999 22:11:05 -0400 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@betaweb.com using -f Received: from smtp7.atl.mindspring.net (smtp7.atl.mindspring.net [207.69.128.51]) by twc2.betaweb.com (8.8.5/8.8.5) with ESMTP id WAA20070 for ; Wed, 20 Oct 1999 22:10:48 -0400 Received: from mindspring.com (pool-207-205-161-176.nwrk.grid.net [207.205.161.176]) by smtp7.atl.mindspring.net (8.8.5/8.8.5) with ESMTP id WAA07752 for ; Wed, 20 Oct 1999 22:08:06 -0400 (EDT) Message-ID: <380E75C2.5665557F@mindspring.com> Date: Wed, 20 Oct 1999 22:09:06 -0400 From: Jim Sower X-Mailer: Mozilla 4.51 [en] (Win98; U) X-Accept-Language: en MIME-Version: 1.0 To: Cozy Builders Subject: Re: COZY: RE: AOA and the Canard.... References: <380BDFF7.B4B7B2F6@vnet.net> Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-cozy_builders@betaweb.com Precedence: bulk Reply-To: Jim Sower X-UIDL: a98ce6a3ff003dbd607f7ba6f9e7086b ... Thus an AOA gauge on the wing is a "hi, you are now going to die" indicator. ... No. "20# of lead in the in the footwell as 'good enough' " is a sure 'nuff "hi, you are now going to die" DECISION. There is no accessory in the world will replace headwork. There is no technology going to prevent anyone from making a stupid decision. AOA to prevent main wing stall (or canard stall for that matter) because someone chooses not to THINK about what his airspeed should be is a case in point. Pitot heat in an airplane that is going to crash from iced up flying surfaces LONG before the pitot tube freezes is another. Stupid decisions are prevented by training and discipline (notice I didn't mention intelligence). They CANNOT be salvaged or ameliorated by technology. Attempting such a thing is an exercise in mental masturbation. Period. Just a theory, Jim S. Date: Wed, 20 Oct 1999 23:01:13 -0400 From: Jim Sower Subject: Re: COZY: RE: AOA and the Canard.... I've only heard of 3 or 4 incidents, and they're all still walking around. Has anyone been in a deep stall and DIDN'T survive? Inquiring minds need to know ;-) Jim S. Date: Thu, 21 Oct 1999 04:51:31 -0500 From: Bulent Aliev Subject: Re: COZY: RE: AOA and the Canard.... Jim Sower wrote: > I've only heard of 3 or 4 incidents, and they're all still walking > around. Has anyone been in a deep stall and DIDN'T survive? > Inquiring minds need to know ;-) Jim S I believe there was one in Palm Beach FL. He was trying very hard to do something stupid and ended up deep stalled upside down. The pilot was talking to the tower all the way down. But that was long time ago Date: Thu, 21 Oct 1999 06:15:56 -0400 From: Jeff Russell Subject: Re: COZY: RE: AOA and the Canard.... Bulent Aliev wrote: > I believe there was one in Palm Beach FL. He was trying very hard to do > something stupid and ended up deep stalled upside down. The pilot was > talking to the tower all the way down. But that was long time ago Neal Hunter, Happen in Orlando at 10,500 ft with a 737 flew over with 500 feet above. Neal had no baffles stopping his fuel from going back aft CG. He also had plus angle on the fuel strakes. He had the main wing stalled the airplane before and was told to fix the strakes. He responded that he would never get in that position again. What a loss :-) -- Jeff Date: Thu, 21 Oct 1999 06:50:26 -0400 From: Jim Sower Subject: Re: COZY: RE: AOA and the Canard.... Inverted will tend to make for a more unpleasant outcome. So far then, all the _upright_ deep stalls I've heard of the guy survived.
Stumblin' in the dark, still searchin' for the truth ;-) Jim S. From: "Frank Johanson" Subject: Re: COZY: RE: AOA and the Canard.... Date: Thu, 21 Oct 1999 10:09:44 -0400 Yes there was a deep stall in a velocity in Canada around the lake Huron area. Stall happened at pattern altitude and the test pilot was killed. This was before velocity modified the wing. Frank Johanson Date: Thu, 21 Oct 1999 09:52 -0500 (CDT) From: Michael Pollock Subject: Re: COZY: RE: AOA and the Canard.... Frank Johanson wrote: >there was a deep stall in a velocity in Canada around the lake Huron area. >Stall happened at pattern altitude and the test pilot was killed. This was >before velocity modified the wing. Yes, there was a deep stall in Canada around the lake Huron area. However, the modification to Velocitys wings was already being done. This deep stall crash was due, according to investigators, to low altitude aerobatics and too far aft CG, and I think I remember that the vortilons were not installed. The pilot was light and he attempted to do a ???hammerhead??? stall at pattern altitude. Date: Thu, 21 Oct 1999 13:10:53 -0500 From: David Domeier Subject: Re: COZY: RE: AOA and the Canard.... Mike, re "The pilot was light and he attempted to do a ???hammerhead??? stall at pattern altitude." Sounds to me like maybe for lack of any other explanation for the crash the pilot was blamed for doing a hammerhead in the pattern. Unless there were mental problems, no test pilot would ever attempt such a maneuver. I would suspect a flight control problem, and not blame the pilot for lack of evidence. dd Date: Thu, 21 Oct 1999 15:29:47 -0500 From: Michael Pollock Subject: RE: COZY: RE: AOA and the Canard.... You could talk to Dwain Swing of Velocity if you need a better explanation of why the test pilot attempted the maneuver. The pilot had been reprimanded earlier due to low altitude aerobatics. He also was flying the plane in an aft CG configuration without vortilons. From: "Hunter Welch" Subject: Re: COZY: RE: AOA and the Canard.... Date: Thu, 21 Oct 1999 19:07:07 -0700 There was one in central Fla in a Velocity, near Apopka Fl . He got caught in the vortex of a 737 and ended up stalling it and comining in inverted. I saw the Plane after it was salvaged and little was damaged except for the canopy area. I have heard that some witnesses said he was alive just before the crash. Bill wFrom ???@??? Thu Oct 21 10:03:21 1999 Return-Path: owner-cozy_builders@betaweb.com Received: from twc2.betaweb.com (majordomo@betaweb.com [206.43.209.18]) by acestes-fe0.ultra.net (8.8.8/ult/n20340/mtc.v2) with ESMTP id XAA24231 for ; Wed, 20 Oct 1999 23:33:00 -0400 (EDT) Received: (from majordomo@localhost) by twc2.betaweb.com (8.8.5/8.8.5) id WAA20519 for cozy_builders-list; Wed, 20 Oct 1999 22:37:24 -0400 X-Authentication-Warning: twc2.betaweb.com: majordomo set sender to owner-cozy_builders@betaweb.com using -f Received: from smtp1.vnet.net (smtp1.vnet.net [166.82.1.31]) by twc2.betaweb.com (8.8.5/8.8.5) with ESMTP id WAA20513 for ; Wed, 20 Oct 1999 22:37:21 -0400 Received: from lmd.vnet.net (lmd.vnet.net [166.82.1.41]) by smtp1.vnet.net (8.9.1a/8.9.1) with ESMTP id WAA19786 for ; Wed, 20 Oct 1999 22:34:36 -0400 (EDT) Received: from popserv.vnet.net (popserv.vnet.net [166.82.1.29]) by lmd.vnet.net (8.9.3/8.9.3) with ESMTP id WAA03467 for ; Wed, 20 Oct 1999 22:34:33 -0400 (EDT) Received: from vnet.net ([166.82.250.82]) by popserv.vnet.net (8.8.8+Sun/8.8.8) with ESMTP id WAA08996 for ; Wed, 20 Oct 1999 22:34:32 -0400 (EDT) Message-ID: <380E5855.6554F97@vnet.net> Date: Wed, 20 Oct 1999 20:03:48 -0400 From: kent ashton X-Mailer: Mozilla 4.03 (Macintosh; U; 68K) MIME-Version: 1.0 To: "Cozy_Builders@canard.com" Subject: COZY: When is a stall a stall Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Sender: owner-cozy_builders@betaweb.com Precedence: bulk Reply-To: kent ashton X-UIDL: 3881eaf1194328a7d1a8119be1bb6f44 If you run your airplane straight up to zero airspeed and let it swap ends, you haven't done a true stall condition that could lead to a main wing stall and I think it would be unlikely to experience a main-wing stall, even if the CG was too far aft. For one thing, the canard has no air flow over it, same as the wing, so both airfoils are experienceing equal lift conditions (no lift and no drag). As the airplane begins to tail-slide, the rudder's position aft of the CG will rapidly rotate the nose from nose straight up to nose straight down. If you then neutralized the controls, you've never entered the classic canard-mail wing stall mode The stall condition in a canard which leads to main-wing stall and loss of control is a flight condition where the canard is unstalled and the main wing is stalled The worst case (I think) is a moderate nose-high climb in an improperly balanced airplane where the main wing stalls but the canard is not stalled. In a conventional aircraft, the aerodynamic forces at work during the stall are all resisting the transition into a deep stall. In a canard, the aerodynamic forces are assisting the transition into a deep stall. --Kent A. DL Davis wrote: > Well I can tell you that I have stalled my main wing and > it was nothing but a piece of cake to recover. At 5000 ft, I flew the > airplane straight up until it ran out of airspeed, zero airspeed. The > airplane fell back on its tail and then the nose simply fell from pointing > straight up, to pointing straight down. The airspeed built up QUICKLY and I > simply started flying againĪ From: "John Slade" Subject: Re: COZY: When is a stall a stall Date: Wed, 20 Oct 1999 23:44:25 -0400 was said: >In a canard, the aerodynamic forces are assisting the transition into a deep stall. I'm no aero dynamics engineer, but I don't believe thats a true statement. With c of g in range, the Cozy CANNOT even be forced into a deep stall because the canard stalls first, the nose drops and the speed picks up. Hold the stick full aft and she just bobs along happily. I tried this in Jeff Russell's Aerocanard and the effect was very gentle. John Slade, Cozy #757 Date: Thu, 21 Oct 1999 22:22:58 +0000 From: Wayne Lanza Subject: COZY: Velocity Incidents Regarding the previously discussed Velocity incidents, here are a couple of facts about these crashes. 1- Fellow EAA chapter member Neil Hunter died shortly after impact after he was vectored by Orlando (MCO) ATC through wake turbulence of a 737. The ATC/FAA initially cited pilot error, but Neil's family didn't buy that. Further investigation revealed that, although legal separation was maintained by ATC, the residual wake turbulence wasn't moving at 350+MPH as was the 737, i.e. Neil went through that airspace soon thereafter. Later it was also learned that the same AT controller vectored a Cessna 210 and a Stearman into the same airspace a year earlier. They mid-aired, the '210 with 3 aboard made it down OK, the other pilot perished. The Hunter Family sued & won. 2- The Velocity crash in Canada was the result a real lack of regard for the rules, safety and common sense. The pilot was reprimanded on several occasions by the CAA, he may have even been flying without a ticket? He had already pulled off a few 'questionable' maneuvers in an aircraft with very few hours on it. Was he trying to pull a hammer head? Could be. Scott Swing had to go up there, on "invitation" of the CAA investigators. He was told that the pilot had performed a few no-no's at LOW altitude. Upon examining the wreckage it was also found that one of the canard hold-down bushings in the canard bulkhead was in the wrong location. The bushing was installed so low that the hole in the canard lift tab was only about 1/4" from the bottom of the tab's bottom. Witnesses said that it looked like the "front wing" bent up when the plane's nose went up, i.e. one of the canard bolt ripping out of the lift tab. The wing cuff kits were sent to this builder, and all of the early original wing owners free of charge. They were not installed. These are the facts as I get 'em Guys. As many of you know, I'm close the Velocity, it's a great plane & they are good people. The Swing's, Nat and the rest of us are saddened and at times angered by some of these incidents. The only consolation is that maybe something will be learned from it all! Take Care & Safe Flying Wayne Lanza From: "Frank Johanson" Subject: Re: COZY: Velocity Incidents Date: Thu, 21 Oct 1999 23:37:03 -0400 Wayne The info on the Canada velocity crash. It is a shame that the owner was not the one that was in the plane at the time of the crash. Frank Johanson From: cdenk@ix.netcom.com Date: Thu, 21 Oct 1999 23:49:17 -0400 (EDT) Subject: Re: COZY: When is a stall a stall Was said I'm not an aerobatic pilot! And don't take this as an alarmist. This is the standard reaction of a canard, but is only one (and probably the most benign) of many possible attitudes (I was going to say intentionally) that the aircraft may get into. But I tend to believe there are more attitudes that may not be as easy to recover from, especially without training. An example: Assuming no spin training, compare a J-3 Cub in a straight stall, with kicking in rudder, and spinning. What happens with a Canard, climbing steeply from high speed, into a near hammerhead? Or as was in a recent message, inverted from wake turbulence. Prehaps someone who is competent in canard aerobatics could discuss recovery from unusual attitudes, and I meam much more severe than the usual practiced under the hood.