Marc Zeitlin

Maybe you could list a few planes that recommend flap usage during climb to improve performance. Not soft/short field takeoff, but climb, as you proposed. Then maybe you could explain how you think flaps would work to do this. Don't ever assume that because someone (anyone) doesn't respond to whatever you (or anyone else) say, that they therefore agree with you. The reasons for silence are manifold. In this case, I was at a John Prine concert Friday night, and then at Copperstate since yesterday morning.

There are at least three contributors to the roll rate issue. First is the raising/lowering of moment of inertia by moving the landing gear closer to the roll axis. The Infinity Gear has the wheels/mechanism pretty far out - further than the stock gear, so it might actually INCREASE the moment of inertia and slow down rolls. The Drybread type gear probably doesn't change the inertia much at all, since the wheels are about the same distance from the roll axis when they're extended or retracted. Next is the aerodynamic resistance (drag) of the leg/pants when moving sideways, as you posit. Remember that the aircraft is moving forward as it rolls, so even with a high roll rate, what you've got on the gear is a high angle of attack, but they're not, by any means, moving sideways - the rotational velocity is still small with respect to the forward velocity. I wouldn't expect this to be a large contributor, but I could be wrong about that. Lastly, since you stated that the canard is smaller, there will be less moment of inertia and maybe slightly less drag, but again, I wouldn't think that would be a large contributor. So, I guess I'm saying that I have no idea why this aircraft seems to have a higher roll rate than normal - there must be some other factor somewhere that we're missing :-). Or maybe my understanding of the inertia/drag issues associated with the Drybread style gear is faulty.

I applaud your promotion of this different type of gear retraction - it's long overdue. However: Apples and oranges - one could change batteries with fixed gear and save the 10 lb as well - the weight difference is 16 lb. That's about what would be expected - glad to hear that your experience follows the theory. Well, yeah - raising the UNFAIRED retractable gear would make a large difference. However, with only a 5 kt. difference in top speed between retracts and well-faired gear, I'd expect to see very little climb difference at lower speeds between retracts and WELL-FAIRED gear - the drag delta would be very low. The problem here, with all these comparisons, is that it's really hard to do side by side apples to apples comparisons..... Interesting. Do you have any other mods that might affect roll rate? I wouldn't expect raising the gear to lower the moment of inertia by a factor of 2......

Do you have any data to back up your belief? Any info suggesting that fixed pitch props have a higher accident rate than CS prop aircraft of the same type?

There are numerous canards flying with variable and constant speed propellers, both on aircraft and auto conversion engines.

Gary Hall is the teflon hinge guy. You're thinking of Gary HUNTER - he and Gordon are the epoxy gurus.

My point was that without lift augmentation devices such as flaps, it doesn't make much difference what airfoil you use - you'll max out the CL around 1.6. Perfectly understandable - neither do I :-). You can put 6.00x6 wheels/tires on these aircraft without any difficulty - it's been done, but the problem is the nose gear, so without a major redesign of the nose gear system, soft grass is NOT a viable option. No, you asked about airfoils, not wing size. But if you're willing to redesign the whole plane, then you can certainly size the wings for whatever speed you'd like to fly. Where is "we"? Your profile does not list a location, so I wrongly assumed you were in the USA.

Did Riblett address the issue of maximum CL (Lift Coefficient) for given airfoils (sans flaps) and it's effect upon airspeed capabilities? This exact topic has been addressed within the last couple of days on the other canard web-forum. Get a Glastar or Zenith. I don't know why that's obvious, except for the nose gear. Since you're redesigning the whole aircraft here, both aerodynamically and structurally, just make the wing large enough to get you the speed you want. LSA are restricted to 1320 lb. Max. Gross and 120 kts max speed. Just these few.

I think so. Where were you at OSH - I missed your heckling at the COZY Forum..... I can stand it, I think. Assuming I understand what you're talking about, it sounds like you want to have the fibers of the carbon at an angle to the longitudinal direction of the fuselage, sort of like if you had used BID at 45 degrees. If that's the case, then yes, this will add to the torsional stiffness of the nose section. If you do those 45 degree wrap layups on the inside of the nose so that they attach to the F-22 and NG-30's, it will definitely increase the torsional stiffness of the nose area. Will it "work"? Hard to say, but the area will be stiffer and stronger, that's for sure. You may want to do the equivalent layup on the exterior of the nose, lapping onto the main fuselage skin as well.

If you could translate that into English and give a little more information about what you're looking for (like type of aircraft, whether you want to hire a builder or visit one, etc.), you may be able to get a useful response. There are numerous canard builders and flyers all over CA.

Sure. But you asked a question for which actual knowledge, rather than newbie-like speculation and mere enthusiasm for changes, would be useful. While there are SOME extremely knowledgable folks here, they're few and far between. Same goes for the other canard specific web based forum, although they get a lot more traffic than this forum does (but the signal to noise ratio is even lower). You'd be far better off asking your question regarding canard aircraft on the canard-aviators mailing list at groups.yahoo.com, if you're really serious about canards. That being said: Not like out of a catalog, no. yes. no.

Since the OP was talking about Velocity's, my response to HIM was about Velocity's, and since Raiki's post was re: COZY's, I mentioned COZY's as well. You miss the point. Whether or not the Velocity factory is interested in developing a twin version (and I don't doubt that they are), they will NOT be moving the engines to "either side of the canard", putting fuel where the engine was, and putting nothing in the strakes. That, I can guarantee. Those were the aspects of the design concept that I was stating would require an almost complete redesign, and that the factory would eschew. Of a "twin" idea - sure. But not of this particular design concept.

No. You've basically redesigned the whole aircraft. Unless you're an aircraft designer, the answer is that you can't do what you're proposing, and even if you were, it would mean changing about 85% of the plane. And Velocity doesn't sell plans, just kits. If you approached them with this idea, they'd either laugh you out of their office (if they were jerks) or very politely tell you that it can't be done and you should do something substantially safer. And although Raiki didn't ask the same question, he'd get the same answer if he did ask, for his proposed COZY modification.

Basically, yes. I recommend that you join the COZY mailing list if you're going to be building a COZY, then read through the FAQ and the archives. What to buy when will depend upon how much money you have at any given time and how much overhead you want to pay for shipping from ACS or Wicks. There's no right answer. If you have the $$$, yes.

The truth is that the $14K estimate was made in 1991, when Nat drew up the plans. That's 15 years ago. Once you get the plans, all will be clear. You need everything for I and II. The chapter kits are just another way of getting stuff.

Much better. Vince, see the pics. That's what it should have looked like in the first place, but I can understand that on the L.E., a space was needed for the battery, with the original short nose.

Actually, what I pointed out was that the horizontal section above the knot in between the pivot point and the "4" in "4Ply" should be raised, and that the corner above the "P" in "4Ply" is the one that should be radiused, since that's a high stress area.

Engine out, prop stopped, figure on 13:1. Some folks will quote you 16:1, but that's with the engine at idle and the prop turning. Assuming you could get that high at gross or above, which you can't. Maybe low 20's, after an hour of climbing. Do you think that we'd admit it in a public forum if we had, since it's illegal without a waiver from the FAA? Now hypothetically, if a person were to attempt a takeoff at ~6000 ft DA at 2200 lb. in a 180 HP COZY MKIV at a mid-CG, I could be pretty sure that it would take about 4000 ft. of runway to break ground, and that the EVENTUAL climb rate, after about 15 seconds of acceleration, might be around 700 fpm. First, define the Density Altitude, and what you believe Gross Weight to be. Do you have a climb prop or a cruise prop (or a CS prop)? How much HP? Where's the CG? So, right out of my butt: 180HP fixed cruise prop, SL Standard Day, 2050 MGW, rear CG - Nat's plane, essentially - 6000 to 8000 ft. would get you off the ground with a few hundred fpm climb rate. Maybe.

I seem to have become a resident expert in sanity checks. Physically what you propose is eminently possible. I considered (for about .003 seconds) doing the same thing to extend the range, until I actually SAT in my plane in the air for 4.3 hours and decided that 5 hours would probably be the point at which I'd start waving the UZI around and demanding that the pilot land the freaking plane. Cuba - Afghanistan - don't care - just get the thing on the ground. There are a few issues, however. First: with the 1000 lb. payload of the MKIV and 320 lb. in the regular tanks, adding 450-500 lb. of fuel will take up ~800 lb of the 1000 lb. That leaves you room for ONE person, not two, unless you want to start the flight 200 lb. over gross (and get the permits to do so, or else certify the aircraft at a MUCH higher weight than anyone else has done). Secondly, carrying ~800 lb. of fuel, or about 133 gallons, will get you somewhere between 2000 NM and 3200 NM range, depending upon speed and fuel flow (assuming no wind). Assuming that you want at LEAST IFR reserves, you've actually got about 125 gallons usable. At a fuel burn of 10 gal/hr (full throttle at 8K ft.), you'll true out at about 180 kts. That'll get you 2250 NM, or just about the distance from LA to Honolulu, in about 12.5 hours (no wind, remember). If you're willing to throttle back to 7-8 gal/hr., you'll get about 160 kts and maybe 2600 NM range. You'll be in the air for 18 hours. If you REALLY want to extend your range, and fly at best L/D speed (about 100 kts) with a fuel burn of ~4 gal/hr, you'll get the 3000 NM range, but you'll be in the air for close to 31 hours. Yeah, right. As you postulate, any weight in the rear seats doesn't change the CG much, and building a tank and tapping into the fuel line is NOT anything insurmountable for someone that's built an airplane - it's been done before. As Dave S. points out (and the web page http://xpda.com/flyingtoeurope/ clearly shows) there's no need whatsoever for extended tanks if all you want to do is cross the north Atlantic. Even flying the South Atlantic, from S.A. to Africa, only requires about a 1500 NM range. Cross Pacific flying is really the only place where you need the extended range. So, it is possible, with a COZY? Sure. It's been done with L.E.'s, and it's only easier with an airplane that can carry twice as much payload. Just remember that the last person to attempt it, in a COZY III from Hawaii to the mainland, crashed a couple hours out of Hawaii, lost his plane, and had to be rescued and was lucky to survive.

Side loads on the wheel will produce a twisting of the NG-30's. One side will try to go up, and the other will try to go down. In NORMAL use, where the nose gear castors, the side loads, and hence twisting of the NG-30's, is extremely low. With the shimmy damper set to provide a maximum side force of approximately 4 lb (what the COZY plans call for) and a gear strut moment arm of about 2.5 ft., the maximum torque that could be applied to the NG-30 torque box is about 10 ft-lb. Since the NG-30's are about 4" apart, you'll have a force of about 30 lb vertically up on one side, and 30 lb. vertically down on the other. Not much. The only times that I've heard of NG-30's breaking (and the only time MINE broke) is during extraordinary circumstances, like taxiing through a pothole or landing with one brake locked (my situation). These put enormous fixed loads on the gear/NG-30's that they weren't designed to withstand. Now, with fixed steering (especially touching down at 120 mph with the nose gear cocked 45 degrees to one side, as would be the case in a hard crosswind landing while using maximum rudder), a coefficient of friction of the tire on the ground of 0.8, and a couple hundred lb. of weight on the nose gear, with a "G" load of 2 in a hard nose slapdown, we come up with nose wheel side forces on the order of 225 lb., or about 60 times as high as the normal maximum loads. All rough orders of magnitude, but I think you can see my concern. strengthening and/or stiffening the NG-30's certainly can't hurt, but if you look a the pics on my web page: http://www.cozybuilders.org/2004_Western_Trip/2004_Western_Trip_day_06.htm You can see that there are a number of things going on. First of all, you want to raise the "level" portion of the NG-30's so that there's more "meat" vertically. Second, you want to eliminate the "corner", where you can see the tear began - any sharp corner is a stress concentration - this should be a large radius. Third, you can see that a large part of the NG-30 structure ripped out of the nose and tore out a part of F-22 - strengthening the NG-30's will only guarantee more damage to the rest of the structure when they rip out intact. Extra ring bulkheads MAY help, as would spreading the NG-30's much farther apart and using a wider pivot structure - you want to attempt to transfer the loads into the nose further out. You'd probably have to increase the strength of the internal nose floor and walls to take the loads, as well. Nope - can't say that.

Sort of - you added trail by moving the axle (and hence the tire contact patch) behind the point where the steering axis intersects the ground, but your "rake" angle is still zero, since the steering axis is vertical. That's not necessarily a bad thing - there are many parameters that intereract here - some aircraft have essentially vertical nose gear struts (and hence steering axes). However, you were talking about angling the strut rearward, like the standard L.E. strut - this would give a NEGATIVE rake angle and steering axis, and that's NOT a good thing.

Neither. They taught me how to learn and the basics of engineering. Vince, I was going to write: "did you study 'Personnel Management' because you were incapable of learning a profession that required actual talent?", but I decided that insulting you back would be lowering myself to your level, so I didn't. You wanna start this conversation over again, without the insults? Or at least in private, if you'd like to insult me? My email address is at the bottom of every post I make - feel free to use it to communicate with me directly. No, actually, "rip it to shreds" is layman's speak. In engineering speak, I performed a design review and gave critical feedback. Engineers do this all the time in design reviews - that's what the design reviews are for. Or was your English structure poor, and did you mean: "You used engineering speak to rip it to shreds"? In which case, I would respond that given that Tony is performing engineering to design his gear, and since he will need to use engineering tools to determine the quality/validity of his design, engineering speak would be the appropriate language in which to provide the feedback. When a design has serious defects that will lead to safety issues, "rip it to shreds" is the appropriate path. Or would you rather that I said "hey, go for it - maybe it'll work!"? What makes you think that just because I can recognize an issue, I can come up with a solution for it quickly enough to make it worth my time and effort to do so? You have been watching my responses on this forum for all of 3 months - that's approximately 2.2% of the time that I've been involved with canard aircraft (11.5 years, for the mathematically challenged). If you were a member of the COZY mailing list, the canard-aviators mailing list, or this forum for more than just 3 months, you'd have seen that I've solved many issues for people and assisted them greatly. I am currently assisting one forum member with a major design change that he's implementing (and due to the amount of time involved, he's paying for it, too). Tony asked for feedback and comments - I gave them. Hopefully he'll be able to use them to refine his design and make it work well. If you don't understand the concept of an engineering design review, Vince, maybe you should refrain from commenting.

I realize that - I was just saying that if it is OK to use tapered rollers in the wheel axle, then it should be OK to use them in your assembly as well, since they're no more likely to get exposed to dirt/grime there than at the axle. It's not a question of the "style" of casting, it's a question of the geometry of the steering axis vs. the wheel axle position. On a motorcycle (or car, for that matter), if you look at the steering axis (or the kingpin angle on the car), it's ALWAYS tilted backward, meaning that the TOP of the rotation axis if further to the rear than the bottom of the rotation axis. Also, where that axis hits the ground MUST be in front of the center of the contact patch of the tire. Since you have removed the "trail" in the casting (you've put the axle directly in line with the steering axis), if you put a negative rake angle on the system, to mimic the angle of the stock gear strut, you will end up with the steering axis hitting the ground BEHIND the center of the tire contact patch. This is unstable. It's like trying to drive your car backwards at 90 mph - any tiny perturbation, and you're off in the weeds with a hard-over wheel, especially since you won't have "hard" steering connection - just the gas-springs. If you put trail back in, that will help by getting the contact patch behind the point where the steering axis hits the ground, but you still don't want the steering axis angle to be negative (bottom further aft than the top). For stability reasons, the steering axis should be tilted back at the top, as described above for motorcycles, cars, and steerable nose gear on aircraft. Yes, Rhino has the ability to do volume calcs, and knowing the density, you get weight.

1) The wheel itself already used tapered roller bearings, and they take at least as much of a beating as the rotating bearings you're looking at. Dirt and Grime is not an issue if you use sealed bearings. Why would this be a special case? 2) A backward rake angle will destabilize the system. You need rake and trail (See any motorcycle fork geometry) for stability. You used to have a "L.E./COZY" style casting to hold the nose gear - you've gone away from that , so you've lost any trail you might have had. Take a look at any straight gear nosewheel - they're angled forward (wheel steering axis contacts the ground AHEAD of the tire contact patch - NOT behind it). Why did you change from what probably could have been a stable system to an unstable one? 3) Springs do not provide "damping" - damping is an ABSORBTION of energy, not a transmission of it from one form (kinetic) to another (potential). There is no damping mechanism in the Wilhelmson gear (I know, I have one). 4) You have no "shimmy damper" that I can see. With a very small diameter rod providing the steering force from the top to the bottom of the strut, you have a system that is very torsionally compliant. Without shimmy dampening right at the wheel, with high compliance (low stiffness), and especially with an unstable geometry, you will be susceptible to vicious shimmy in this system. 5) Assuming that you're using a 3D solid modeler, you should be able to calculate the weight of the system easily, by assigning materials to each part and asking for material properties. Are you not using a modeler that can calculate weights automatically? 6) In your original design, you were using a steering tiller - what happened to that idea that made you switch to using the rudder pedals? 7) What will happen if you partially extend the gear 1/2 way (to move the plane around with no weight in it on the ground), the wheel goes off to one side, and then you attempt to fully extend the gear without straightening the wheel? Will the engagement mechanism engage with a 90 degree wheel angle? Can you rotate the wheel 90 degrees sideways when the engagement mechanism isn't engaged to facilitate ground movement? 8) With the gear fully extended and the engagement mechanism engaged, you state that you have a 43 degree rotation angle capability. This will increase the turning radius from the stock 98" to about 135 - 140". Not a real big deal, but not as tight as before. You understand that you are giving up some ground handling capability here, right? 9) The dual gas springs (or equivalent) that you plan to use between the rudder pedals and the steering mechanism introduce another point of compliance into an already very compliant system. This greatly complicates the vibration modes of the system, as well as substantially lowering the vibration frequencies of the system (and increasing the possible amplitude of vibration). 10) I don't see any modifications to react the huge side loads that will be developed when steering at high speeds - since it's not possible for the system to ONLY castor (the gas springs are always engaged), there is the possibility that with the wheel off center, or in a crabbed landing, there will be LARGE forces that will be reacted into the gear strut and the NG-30's. How will your system deal with these loads, that a standard system never sees? There might have been more, but I can't recall off the top of my head. Thanks for the opportunity to review your design - it's very interesting.

I will agree with this statement. Having the ring substantially stiffens the structure, and having some cross-members as you sketched would substantially stiffen the conical mount design. Since the back side of engines with conical mounts is not substantially different than engines with Dynafocal mounts, what you've proposed would be possible. However, all that said, no amount of cross members will turn an engine mount of this type from an indeterminate structure to a determinate one - unless you were willing to use ball/pin joints at every tube intersection. There's "CORRECT" and then there's "ADEQUATE". While I will certainly agree with you that this design is not optimal from a load paths standpoint, without a stress analysis, it's not possible to claim that it won't work. It IS possible to claim that it MAY have bending moment issues, but that's something that can be addressed by looking at the population of non-cross-braced conical mounts and obtaining the failure rate. If the imposed bending moments, even under vibration loads under "G" loading, are lower than the fatigue limit of the 4130 steel, then it doesn't matter that the mount would be structurally more efficient with different load paths (and the claim of structural efficiency is dependent upon the increased thickness of the existing tubing weighing more than the extra tubes for bracing would have weighed). It would work - that's all that anyone will care about. Absolutely true. But 23 years of experience without failures would make it ADEQUATE, if not optimal. I have no idea if that's the case, but it might be. It's one of the things to consider. A seperate set, yes, but intimately tied in. If the engine attached to this mount put out 20 HP and weighed 40 lb., I don't think this discussion would have occurred. Conversely, if it put out 2000 HP and weighed 1500 lb., it would be fairly obvious that the mount was inadequate. We're somewhere in the middle, and that's why you had the gut feeling that there MIGHT be a problem. And there might - as I said before, I'd feel better about it with some more bracing on the top, but IF O-320's have been mounted to this design for 20-40 years, and have worked, then my gut feeling was misplaced. Here are some pics of mounts used for lower power engines that have similar configurations: http://www.greatplainsas.com/scengmounts.html Well, you bring up some good points, but using certified GA aircraft, most of which were designed 60 years ago by folks who may or may not have done any analysis or much testing, and which, by and large, have failure rates of systems and components that would NEVER be tolerated in a consumer or automobile marketplace as an example of something to emulate is not one of them. Always.