Date: Mon, 1 Apr 1996 12:52:21 -0500 From: Phillip.Johnson@Lockheed.on.ca (Phillip Johnson) Subject: RE: short canard? Larry Schuler Writes. > Phillip, maybe we need to design a variable elevator limit tied to > airspeed I'm ahead of you on that one. My thoughts were to include a two position stop that could be electrically or manually implemented. On take off the stop was withdrawn and the system defaulted to higher elevator angles. After take off the shallow stop was reinstated thereby giving the normal flight conditions that keeps Nat happy. If the two position stop were implemented electrically, (solenoid,) then a control stick mounted button like the PTT switch could activate this mechanism. Press the button during rotation thereby giving more elevator travel. after rotation the button is released and normal flight conditions prevail. The thought also crossed my mind that this might be a good way to reduce landing speeds for forward CofG conditions if the landing under these conditions is elevator limited. Of you guys out there who are flying, do you find that you are elevator limited on landing? Phillip Johnson Conversion: Allowed Original-Encoded-Information-Types: ( IA5-Text); Disclose-Recipients: Prohibited Alternate-Recipient: Allowed Date: 22 Oct 1996 11:03:18 -0600 From: "Stagl, John" Subject: COZY: S-glass Hello everyone, I've just got my plans and am anxious to start. Has anyone considered using other composites? S-glass in the fusilage, bulkheads, spars - carbon fiber or kevlar in reinforcing layups. I'm considering using s-glass - same weave (bid, uni) same number of plys - as specified. I would not alter materials in the main wing, not wanting to affect flex, if there is any built in. I be glad to hear if anyone else has tried this, I'd also be glad to hear comments if this is not a good idea. Thankks John Stagl stagl.john@tcinc.com Date: Tue, 22 Oct 1996 17:30:46 -0500 From: Mahan Subject: Re: COZY: S-glass Stagl, John wrote: > > Hello everyone, > > I've just got my plans and am anxious to start. Has anyone considered using > other composites? S-glass in the fusilage, bulkheads, spars - carbon fiber > or kevlar in reinforcing layups. I'm considering using s-glass - same weave > (bid, uni) same number of plys - as specified. I would not alter materials > in the main wing, not wanting to affect flex, if there is any built in. I > be glad to hear if anyone else has tried this, I'd also be glad to hear > comments if this is not a good idea. > > Thankks > > John Stagl > stagl.john@tcinc.com John, why do it? Following the plans will save you time and money. Fred Conversion: Allowed Original-Encoded-Information-Types: ( IA5-Text); Disclose-Recipients: Prohibited Alternate-Recipient: Allowed Date: 15 Nov 1996 15:03:48 -0700 From: "Stagl, John" Hi folks, I'm a new builder, working on bulkheads right now. There has been a lot of discussion on air foils. I've noticed some Cozys with a dyhedral in the Canard, but I've not heard or read anything about this modification. Has anyone tried a BIG winged version, something along the likes of the Velocity 173? I can see some benefits in low speed performance. Design modifications are often a sensitive issue but I'd be interrested in hearing comments. Also, I'm new to the Bay Area (California) and I'd enjoy meeting other builders in the area. John Stagl Pittsburg CA Date: Fri, 15 Nov 1996 18:16:23 -0800 From: berkut@loop.com Subject: Re: dyhedrald canard Vance Atkinson put some in his on the theory that it would raise the canard tip vorteses (sp? vorteces?) above the strakes and wings and increase cruise speed, and increase roll stability. He says it didn't do much, if anything. > >I'm a new builder, working on bulkheads right now. There has been a lot of >discussion on air foils. I've noticed some Cozys with a dyhedral in the >Canard, but I've not heard or read anything about this modification. > -- Czech Sikhs! Richard Riley "The important things are always simple. The simple things are always hard." See the Berkut at http://www.berkut.com Date: Sun, 17 Nov 1996 22:55:14 +0000 From: Jnik Subject: COZY: Re Eppler 1230 airfoil This is my first posting to the group. The discussion on wing airfoils appears to be too important to not reply, so here is my .02. I am not a professional so take what I am about to say with a grain of salt, but before making ANY changes to your wings please consider the following. One of the reasons the GA laminar airfoil was changed was the fact that in rain, or even near a cloud, the laminar flow would be tripped causing a change in the stick pressure required to keep straight and level. It was a rather unfamiliar feeling for those of us used to C150's. It is not dangerous, but it is different, and it increases pilot effort when flying in moisture. Because of this a different airfoil was designed by John Roncz which is the one we currently use. The second thing to consider is much more important. The existance of the deep stall on a canard airplane is due to the fact that a typical stall curve is not what you would expect when you look at it many degrees past the stall point. Most sections do not experience a uniform continuous drop in lift with increasing angle of attack. At a certain point past the angle at which the section stalls, lift again begins to increase. If the aircraft gets caught in this "valley" on the canards lift curve, and the main wing is in the stable portion of its lift curve and providing enough lift to not allow the airplance to fall on its tail, you end up in a stable deep stall. Most airfoils do not have published stall charecteristics that allow the typical homebuilder to take into account this behavior. Not only is the deep stall behavior not available on most sections, but also remember, the canard wing is a very short chord wing flying at relatively high speed, therefore not only do you have to understand the deep stall characteristics of a given section, but you have to know what happens at Reynolds numbers usually not available in the references. Another thing that most people do not understand, is that even minor changes to the main wing can seriously effect deep stall behavior. For example the changes that Klause Savier has made to his bird would increase its likelyhood of a stable deep stall, or looking at it another way, change the allowable aft center of gravity. Breifly, the reason for this is that by changing the winglet we change several things. The changes he made to the winglet have the effect of reducing the effective span of the wing. This increases wing loading by reducing effective main wing area. This makes the plane faster. However by reducing effective main wing area you change the "balance" between the main wing and the canard. I could get technical here, but think about the experience of Nat when he tested the Mark IV. The original prototype did not have the lower winglets and showed some pretty bad behavior. This was partly because of the missing lower winglet. Nat talks about the lower winglet protecting the lower surface of the main wing from stall. In reality, it is simply that by removing the lower winglet we have reduced effective main wing area, and thereby changed the balance of the flying airplane. In effect this causes a reduction in the allowable aft center of gravity. I believe Barnaby Wainfan had an article in Kitplanes not too long ago that not only covered most of this stuff, but came with the appropriate graphs to make it a little easier to understand. The summary here is that changes to wings are MAJOR modifications, and should be done with a great deal of care! John Meernik Date: Mon, 18 Nov 1996 17:35:52 -0500 From: CheckPilot@aol.com Subject: Re: COZY: Canard Dihedral In a message dated 96-11-17 23:59:39 EST, you write: << A little dihedral (about 3" at the tip) will probably make the plane even more stable and possibly allow the canard vortices to mostly flow over the top of the wing during landing. It will be a little harder to build to get the dihedral equal on both sides, but not that bad. You'll have to talk to the builders who actually did the change to see how they did it and how they like it. >> Get in touch with Vance Atkinson, he did a bent canard and sells the plans to do it for the cozy III. I haven't gotten started yet but I have his plans. It doesn't look tough (he provides a few pictures too). Jim Hann Cozy III #455 ATP/MEL Date: Mon, 18 Nov 1996 18:49:28 -0500 From: CCady@aol.com Subject: Re: COZY: Canard Dihedral In a message dated 96-11-17 23:59:39 EST, you write: << COZY_BUILDERS@hpwarhw.an.hp.com (Cozy/Canard Builders) John Stagel wrote: >I've noticed some Cozys with a dyhedral in the Canard, but I've not heard or read anything about this modification.< A little dihedral (about 3" at the tip) will probably make the plane even more stable and possibly allow the canard vortices to mostly flow over the top of the wing during landing. It will be a little harder to build to get the dihedral equal on both sides, but not that bad. You'll have to talk to the builders who actually did the change to see how they did it and how they like it. As to whether they like it better than the straight canard and why, they would have had to of flown a straight canard for for awhile for comparison. >> I put some dihedral (about 2" at the tip) in the Roncz canard on my canard. I put the kink in the middle. I laid out the 2 X 4 's used to hold the cores for the shear web layup on angle. It really wasn't too hard. As to how it flys, I seems to have less nose hunting or dutch roll over my Long with a straight canard but It's hard to say if thats what made the difference. I would say that if you want to do yours the benefits may not be dramatic. It does look nice however. Date: Mon, 18 Nov 1996 21:55:10 -0500 From: Mahan Subject: Re: COZY: Canard Dihedral Why do this? To make the plane more stable (maybe) so that it won't roll as well? Does anyone have complaints about how the wing or canard works during landing when they are built per plans? You've got plenty of dihedral effect from the upper winglets. Why not build per the plans and get proven performance? Do you want to experiment, or to build a good performing, proven airplane? Fred in Florida Long-EZ N86LE Defiant project Fred in Florida From: "Dewey Davis" Date: Tue, 19 Nov 1996 10:53:59 -0500 Subject: Re: COZY: Canard Dihedral On Nov 18, 17:35, CheckPilot@aol.com wrote: > Subject: Re: COZY: Canard Dihedral > In a message dated 96-11-17 23:59:39 EST, you write: > > << A little dihedral (about 3" at the tip) will probably make the plane even > more stable and possibly allow the canard vortices to mostly flow over the > top > of the wing during landing. It will be a little harder to build to get the > dihedral equal on both sides, but not that bad. You'll have to talk to the > builders who actually did the change to see how they did it and how they > like > it. >> > > Get in touch with Vance Atkinson, he did a bent canard and sells the plans to > do it for the cozy III. I haven't gotten started yet but I have his plans. > It doesn't look tough (he provides a few pictures too). > > Jim Hann > Cozy III #455 > ATP/MEL >  >  >-- End of excerpt from CheckPilot@aol.com I built a dihedral canard also. It was a little more trouble than the original canard I built, but nothing that should deter you from doing it if you want one. Vance has some nice plans for this. I talked to three other EZ flyers that have done it and asked them if there was any performance change. The consensus seems to be, no. Vance thought he noticed some slight roll improvement, but nothing to get excited about. Some people like the dihedral look better, but thats about the only reason to do it. In my own case, I built this canard last winter along with a bunch of other major mods to the airplane. I ran out of time before I could get it installed on the airplane. I didn't want to miss Sun N Fun, then there another flyin, etc etc. So the canard still sits in my basement. Since that time, I have begun to question whether I really want to take the airplane down to install it anyway. The existing canard I have sure flies fine. On top of that, I now question the structural integrity of the new canard since I built the whole thing with 2427. I have tried a few delam tests near the edges, and couldn't find any areas that did not look right. But I still wonder about that spar to shear web layup that I can't get to. I don't know if I trust this canard just yet. I think I'll wait and see what happens with this epoxy issue before commiting the canard to the airplane. Another idea I have been toying with is to use this canard as a test sample for an ultimate load test, test it to failure. (sometimes it can be a lot of fun to break things!). What would a test like that prove? Maybe not much. But if it did actually hold up through the design load limits, then we would know that it is at least possible to build a safe airplane out of the 2427 epoxy. Maybe I got lucky with low humidity in Virginia over the Christmas holidays last year when I built this canard. On the other hand, if it failed, it would only prove that the epoxy is sometimes degraded by environmental conditions, which we already know. Also, some people have questioned the design integrity of the bent canard anyway. With that kink in the spar, there must be some compromise in strength. Vance added a few plies in the skin and the spar in his plans to compensate for this. But is that enough to restore the strength? Nat sure wasn't happy about this mod, understandably. Maybe a test would put the strength issue to rest too. Dewey Davis Date: Fri, 06 Dec 1996 02:15:38 -0500 From: Jim Hocut Subject: COZY: Armpit Scoops While on the subject of speed brakes and armpit scoops.... Do armpit scoops have more or less drag than the NACA scoops? Has anyone who's using armpit scoops actually done a before and after comparison on the same plane so that we're comparing apples to apples. Jim Hocut jhocut@mindspring.com Date: Fri, 06 Dec 1996 07:45:12 -0500 From: william l kleb Organization: NASA Langley Research Center Subject: Re: COZY: Armpit Scoops Jim Hocut wrote: > > Do armpit scoops have more or less drag than the NACA > scoops? depends on how careful you do either. david lednicer* recently posted in r.a.h newsgroup that he felt armpit scoops were the way to go. he cited nemesis as one example. a recent picture in central states showed the intakes to be slightly larger than a few peanuts laid end-to-end---impressive, although i wonder about ground cooling. --- bil kleb (w.l.kleb@larc.nasa.gov) 72 bellanca 7gcbc 9? cz4 -> aerocanard *for whatever reason, i hold his opinions in high regard. he has done at least a couple studies on the rutan series of aircraft (sae papers 881485 and 892287). Date: Fri, 06 Dec 1996 18:58:37 -0500 From: Mahan Subject: Re: COZY: Armpit Scoops Mike Melvill is trying out a pair of Berkut armpit scoops on his 180 hp Long-EZ, and has had good results so far on cooling. He promises to put a full report on his experiences in the next Canard Pusher. Fred in Florida Jim Hocut wrote: While on the subject of speed brakes and armpit scoops.... Do armpit scoops have more or less drag than the NACA scoops? Has anyone who's using armpit scoops actually done a before and after comparison on the same plane so that we're comparing apples to apples. Jim Hocut > > jhocut@mindspring.com Date: Sat, 07 Dec 1996 09:47:23 From: (Blair Hileman) Subject: COZY: Armpit Scoops Jim: Sport Aviation March 95 had an great article that was about all the mods Gary Hertzler made to his VariEze 99VE.To quote the part about armpit scoops... "Every bit of air the engine needs to breathe and cool itself comes through a hand sized armpit scoop under each wing. Gary says the first time he ever saw that type of inlet was on an EZ belonging to Charles Airesman from Cumberland, MD. He says his airplane in not only beautiful, but is-along with his and Klaus Savier's-among the fastest in the country. This type of scoop works in high pressure air and leaves the belly completely smooth and clean. However, Gary says the performance gains over the NACA inlet are minimal, especially when put against the huge amount of work involved. It does, however, make for a much nicer looking cowl which flows better up to the propeller." Jeff Russell has these scoops for sale. I will get them and the electric landing brake, this should solve the extended brake failure/cooling problem if it occurs. BTW, are you vac bagging you aircraft? I had a few questions if you are. Blair Hileman BlairHileman@trader.com --- * Traders' Connection Web BBS * http://www.trader.com * info@trader.com