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Marc Zeitlin

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Everything posted by Marc Zeitlin

  1. Most? There are 100's of flying COZY's - there are zero with continentals. There is only ONE COZY being built with a continental that I know of. When/if that one flies, then the number will be 1, still not the inverse of "most" :-).
  2. You talk about it a lot with folks that know, and then you try it. Hundreds have done so. It's not so different than an experienced pilot can't figure it out, although the first couple of landings might be interesting. And actually, there IS a stick in the back of a V.E./L.E. - just no instruments, throttle or rudder pedals. You can fly it, but you can't (easily) land it or stop it. Obviously in a COZY, you take conventional lessons for a couple of hours with a compliant owner, just to be that much safer. You can ask the same question about any single seater - you fly it by trying it. I got liability ($1M/$100K) on my COZY MKIV for $700/yr. with about 200 hours. I think L.E.'s are somewhat less.
  3. I had about 175 hours when I first flew mine, all in C-172's and Warriors. I know of a few others that were in the 100-200 hour range as well. There's nothing magic about these planes - a few hours of transition training and you pick up the nuances. See above. You'll have to give us a clue where you are in 3-space. There are many canard folks willing to give rides. Joining the COZY mailing list will get you a database of builders/flyers near you, so you can contact them for a visit. See the URL below. I don't know if the Velocity folks have an equivalent system, but you could contact the factory to see.
  4. In a COZY MKIV, there is a manual roll trim, using springs and a handle. Many people have made modifications to electric trim systems as well. See: http://www.crixbinfield.freeserve.co.uk/Mods/trimspring.htm for a view of the system.
  5. Or you can call your local plastic supply house and rummage through their scrap bin and probably find what you need for $5.
  6. You state this as if it's a well known fact. Actually, there is substantial disagreement as to whether PP adds weight or saves it. I'm in the "saves it" camp, and AFAIK there are NO controlled studies that prove the claims one way or the other. Be careful stating categorically things that aren't so, or at least are not proven to be so. "Some folks claim that PP adds weight" would be an accurate statement, as would the opposite.
  7. If you're ever looking for plans (or a project, or completed plane) the person to contact is David Orr. He is THE guy for finding canard related plans/projects.
  8. Ernest Christley, who's building a DD, has specs on his web page at: http://www.ernest.isa-geek.org/intro.html
  9. Normally aspirated piston engines can develop 75% of their rated HP at DA's up to approximately 8000 ft. This means that at any altitude above 8000 ft., you will have less than 75% power. With a turbocharged engine, you can develop 75% power at higher altitudes, and since drag is less the higher you go (since the air is thinner) you will go faster (up high) with a turbo/supercharged engine than you will with a normally aspirated one. Also, the 75% power is measured from RATED HP, not from "max. available" at any particular DA. I have a 180 HP O-360 in my plane - 75% is 135 HP, which will be available to me at any altitude below ~8000 ft. - above that, I will have less than 135 HP available, even at full throttle. If you can develop more than 135 HP at altitudes above 8000 ft., you will go faster than I will, given the same airframe. That help?
  10. Agreed, for _this_ application - in a glider, the GU would be better (or in an aircraft that is trying to maximize range by flying at the max. L/D point, rather than a faster cruise speed). On the other hand, since the canard is such a small part of the overall flying surfaces of these aircraft, the small difference in drag is almost meaningless for us. The reason for the switch was 99% for bug/dirt/rain resistance, not anything else. Again, the "higher lift" is difficult to interpret in a laymans publication. It's hard to know what they meant, since "higher lift" doesn't have an engineering interpretation. Could be on the V.E., you maybe correct, although I don't remember seeing tabs on the V.E.'s I know - just on the VariViggen. I don't think there is one on the L.E., even with the GU canard, though. Maybe it's called for in the plans, and people just leave them off..... The place to check with folks on the trim tab issue would be on the Canard Aviators mailing list - there are zillions of V.E./L.E. builders/flyers over there.
  11. There are a number of builders and flyers in the Pac. NW. I'll be coming through there in mid-July - see: http://www.cozybuilders.org/2004_Western_Trip/index.htm If you want to get in touch with folks near you, you should join the COZY mailing list - first of all, you'll have access to more people flying COZY's than hang out here, plus you'll get a database with folks real names and locations to search through. You're asking a number of different questions here. If you want to take lessons and get instruction in a COZY, you'll need to find a CFI that's willing to teach in one. If you're talking about merely getting checked out in a COZY so that you meet insurance requirements to get insurance to fly one (presumably your own), then any PP can check you out in a COZY. I checked out Steve Brooks' down in FL in April, prior to his first flight in HIS plane - I gave him 1.5 hours and 5 or 6 takeoffs and landings in the left seat. I'm not sure what you mean regarding "commercial" use - recently (a few years ago) the FAA changed the rules and allowed people to rent Experimental Amateur Built aircraft for the purpose of a checkout flight, but renting the aircraft and renting a CFI are two completely different things. When I give folks rides or check them out, I let them pay for the pro-rated shareable cost of the flight, per FAA regulations. I'm not a CFI, so I can't give instruction or get paid for it. I found a CFII that gave me my biennial review in my plane last August for $40, and is willing to give me instrument instruction in my plane for $40/hr. Not a problem. I've never heard anyone say that it took them more than a couple hours to transition from a C-172 or Warrior into a COZY. Then you haven't seen the Owner's Manual or the web pages at: http://www.cozybuilders.org/performance/ Enjoy.
  12. No question, but..... This statement (in an aerodynamic sense) has no particular meaning - i.e., it could mean one of a number of things. To explain why, I'll need to get into aerodynamic theory. In 2D aerodynamic theory (and verified by wind tunnel testing), the lift curve slope of ANY sharp trailing edge airfoil is: Cl=2*PI*alpha where alpha is the AOA measured from the zero lift line of that airfoil. In 3D theory (and verified in wind tunnel testing) the lift curve slope is: Cl=(2*PI*alpha)/(1+2*AR) where AR is the aspect ratio of the airfoil (for the COZY canard, it's about 10-12). This, again, is completely independent of the airfoil shape, as long as the trailing edge is sharp. Now the shape comes into play. Depending upon the shape, different "alphas" are achievable - some airfoils can obtain higher angles of attack than others, and thereby achieve higher maximum Cl's. So the question is, what did they mean in the CP when they said the Roncz had "higher lift" than the GU? __ALL__ airfoils have the same Cl at the same relative AOA, so they couldn't have meant that the lift curve slope was different, and they couldn't have been referring to the _maximum_ Cl achievable, because the GU can achieve a higher maximum Cl than the Roncz can (Xfoil analyses of both airfoils show the Cl/Cd curves - I'll be presenting these results [from Todd Parker] at OSH). The following statement gives a hint of what they PROBABLY meant (and we have to remember that the CP's are written for a lay crowd, NOT for aerodynamic engineers): When tying the DRAG into the issue, the Cl/Cd curves may explain what was meant. From Cl's of 0 to about 1.0, the Roncz canard has a lower Cd (about 30% lower) than the GU canard. Above a Cl of 1.0, the GU has substantially less drag than the Roncz (up to 75% less). While both airfoils have maximum Cl/Cd ratios of about 120, the Roncz canard produces this at low Cl's, whereas the GU produces this at higher Cl's (closer to stall). This is not surprising, as the GU was developed as a laminar flow glider airfoil, and gliders spend most of their time at low speeds. For a cruising aircraft, however, the Roncz is more efficient at lower Cl's, and if you're willing to give up something near stall, then it's possible that operating the Roncz at a slightly higher Cl than you would the GU would allow the changes (and advantages) indicated above in the CP. So, the statement "higher lift" doesn't mean anything in an engineering sense (which is how I was approaching it), but I can certainly see that from a layman's standpoint, the CP's wouldn't have gone into this kind of detailed explanation - for most folks it won't mean a hell of a lot unless they're interested in understanding the underlying aerodynamics of the aircraft. PS - since there are no "external devices" on the V.E.'s or L.E.'s that I've seen with the GU canard, I'm not sure what the reference to them means in that CP statement with respect to the Roncz.....
  13. Lead is 13 times as dense as water. To get 50-60 lb of water, you'd need a cubic foot of space. That much space would be very difficult to find in the nose of a COZY. Vance Atkinson (IIRC) said he tried that once, and it was a PITA, as well as taking up way too much room.
  14. This is incorrect. When clean, the GU has a higher maximum Cl than the Roncz, and also lower drag at higher Cl's. The GU (at least as implemented on the V.E., L.E., and COZY) did not have any external "tabs" for trimming the elevator loads, any more than the Roncz does. Nat cut the canard length due to his interpretation of deep stall considerations, NOT because the Roncz airfoil allowed it. In fact, when clean, the GU would have had an even worse effect on the deep stall tendency, due to it's ability to operate at higher Cl's, and would also have required (in Nat's view) a canard shortening - possibly even larger than the existing shortening. The Roncz has much better Cl and Cd characteristics when dirty (but neither airfoil likes to operate this way).
  15. You do NOT need an aircraft specific certification - just equipment that meets the requirements. For ANY approaches, you will need a VOR in the plane (ref. the "ground based" requirement) - this is why the Garmin 430 etc. have a VOR built in. The BMA unit is not certified in any way. However, what the rules say is that the equipment must meet the TSO C-129A _standards_, NOT that it has to be certified in that category. __IF__ the BMA equipment meets the standards, you can use it (although you might have an argument on your hands if you ever have an accident and the FAA investigates). BMA will NOT tell you to use their stuff for IFR.
  16. Oh, boy. Here we go again with this :-). See: http://members.eaa.org/home/homebuilders/faq/Equipping%20a%20Homebuilt%20for%20IFR%20operations.html You might need to be a member and have a login to read this. So, certification means nothing in a homebuilt, but that does NOT change the requirement to be equipped per 91.205, which explicitly states: "Two-way radio communications system and navigational equipment appropriate to the ground facilities to be used."
  17. The CSA is alive and well. See: http://www.cozybuilders.org/ref_info/other_news.html For subscription information. The CSA did/does not keep a web page - "www.canard.com" was owned and maintained by Wayne Wright, who, in February, had a massive server crash and decided not to expend the energy maintaining the site anymore. Bits and pieces of it have moved here and there, but it hadn't been maintained in a long time and was substantially out of date. A CSA newsletter index can be found at: http://www.cozybuilders.org/ref_info/
  18. West is most certainly NOT acceptable as a structural epoxy - I believe that the plans explicitly say this, but if they don't, it's been said in the newsletters and the on the COZY mailing list many times. Order whatever epoxy you need far in advance, if it takes a long time to get there, but do NOT substitute unapproved epoxies.
  19. Both ARE derivatives of the L.E., and use exactly the same WING planform, shape, and structure (although the COZY wings have more glass in the spar due to the heavier weight). However, the strakes could be different sizes, so the total area would be slightly different. No. Although the Eracer may use the old GU canard airfoil, rather than the Roncz, but I don't know about that. I've never seen a CAFE report for the Eracer - check the cafefoundation web site for a list of the planes they've tested. Yes, well, weights are always attributable to weight :-). The Eracer is a 2 seater, and the COZY is a 4 seater, so the gross weight of the COZY will be higher. The COZY speeds are close to the claims. I've never seen two Eracers that had the same engine, so it's hard to say what the performance SHOULD be. You also need to be careful about comparing Vne's and Vmax's, as well as IAS and TAS.
  20. It is a MODIFIED Eppler 1230 - it is NOT the stock 1230 airfoil that you will find. The modification involves removing some (but not all) of the T.E. reflex, but no-one has ever been able to get a perfect description of exactly what was changed. The airfoil has been reverse engineered, however, from the L.E./COZY templates (innacurate though they are, being on paper and all).
  21. Sprayed fiberglass is made up of chopped fibers and vinylester resin, while the hand layups are made up of continuous woven cloth and epoxy resin. If you're building a boat (or a corvette, as pointed out) the former is adequate, but the strength and stiffness will be lower, the weight will be much higher, and the vinylester resin's characteristics suck (that's the technical term) in comparison to the epoxy. It's almost impossible to hold thickness when spraying, and there are no molds. Follow the plans :-).
  22. It is extremely unlikely that it could. While no COZY has ever lost an aerodynamic surface in flight, a Vari-Eze or Long-EZE (don't remember which it was), lost a winglet in flight, due to an extreme builder error (he had apparently left the peel ply in the main structural layup that held the winglet onto the wing). After 40-50 hours of flight, the winglet departed and the plane crashed. So, the evidence would apparently indicate that controlled flight in such an asymmetric configuration would be problematic at best.
  23. The landing brake was a very early modification to the Vari-Eze - it's mentioned as early as CP #11 in 1977 as a test modification to the V.E. AFAICT, the Long-EZE always had the landing brake in the design, as did the COZY. CP24 was the earliest mention (I could find) of the L.E., and it discusses the Landing Brake as an integral part of the design. That's true, although I find it to be very useful in controlling glide path. The only time I won't use it is if I've got a long runway (more than 4000 ft or so) and a stiff headwind. It allows me to land with a much steeper glidepath than without it. In CP11, Burt mentions that the landing brake should reduce the minimum field length for the V.E. from 2400 ft. to 1800 ft., indicating steeper approaches and better spotting of landing points.
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