Marc Zeitlin

One other way is to research the areas of interest before asking questions. Had I been intending to be condescending, I would have been. All of my comments were statements of fact. I wasn't rude. I was presenting facts for the umpteenth time. As are we all. I, however, have never felt that anyone owed it to me to hand it to me on a platter, and got upset when they gave me the information I was seeking. Maybe the obverse should be the case, and if you can't find the information you're looking for in archives, web searches, books or old threads here, then you can ask a question while pointing to the information that hasn't answered your question. Feel free to put me on your "ignore" list - I'm rapidly starting to not give a crap regarding helping people not to do stupid things. I truly am beginning (after 12 years) to have an understanding for why some EXTREMELY knowledgable folks just keep their mouths shut, rather than sharing their knowledge, to all of our detriments. I give up.

I work for Scaled now. There is no rationale. For non-molded parts, there will be zero reduction in sanding/finishing. Bagging is an attempt to save weight and supposedly get more repeatable, slightly stronger parts. The first is suspect, or minimal at best, and the second is unnecessary, if even possible. Sure. For MOLDED parts, bagging will provide lighter and stronger parts that require less finishing, IF DONE CORRECTLY. If done incorrectly, the parts will be weaker. Sigh. Since neither of these things is an issue in building a structurally sound aircraft per plans, I'm truly at a loss in trying to understand the fixation/fascination that some folks have with vacuum bagging. Let me make this absolutely clear: NO RUTAN DERIVATIVE CANARD COMPOSITE AIRCRAFT HAS ___EVER___ HAD A STRUCTURAL FAILURE WHEN BUILT TO THE PLANS. EVER. EVER. And yes, I'm shouting. No structural or cosmetic problem that canard composite aircraft HAVE had would have been prevented by using vacuum bagging correctly (and "correctly" is important). Is vacuum bagging good? Yes. Is carbon good? Yes. Almost all of Scaled's aircraft are built mostly from carbon and are mostly bagged. But moldless composite construction using fiberglass is NOT the same methodology. You're NOT using molds. You're NOT using carbon. What makes folks think that they need to vacuum bag? Since the COZY MKIV plans don't call for carbon anywhere, you don't need to determine anything. If you're an aeronautical/mechanical engineer with knowledge and/or experience in composite design, then you can analyze the structures and determine material needs. If not, you can spend 4 years in engineering school and then a few in industry learning the skills necessary to "determine the use of carbon". Or hire someone with the skills to determine the usage for you. For what reason, I don't know, however. As stated, an increase in strength is not necessary - these planes DON'T fail. As far as weight reduction is concerned, the canards that are built from carbon, to some extent, all weigh more than their glass counterparts. The Berkut is heavier than the LE, and Chris Esselstyn's stretched COZY is heavier than a standard one, both after normalizing for engine weights and retracts. Go figure. Maybe the guys who drew up the plans had a clue? The COZY plans aren't perfect, by any means - god knows that I've had more than my share of "discussions" with Nat regarding improvements that could be made, and a cursory search of the COZY mailing list archives would show that. But this isn't one of those places. Either for the COZY or the L.E.

It's N8VE - John Lambert's old VE.

At least within the canard composite community of approximately 2000 - 3000 flying aircraft, it's never happened. That I'm aware of. From reading all the CP's and COZY newsletters and following the on-line communities for the past 12 years. EVERYTHING is repairable.

Not to non-members, no, but if you're a member, you receive a database of everyone on the list, their address, phone # and status.

The plans explain what to do in cases like this - look at the inspection and repair section - don't remember the chapter #. I think that the plans recommend drilling a small hole into the bubble and injecting the epoxy from the front, but if you can find the bubble from the back side, that should work, too. I always interpreted it to mean that 10% of the area could be air bubbles.

Don't be so sure. We've seen things move, shift, lift, etc. even under a bag. It's hardly unknown. Depends on a lot of things - epoxy type, temperature, pressure, etc.

I agree with Craig's post #16 above, cross-posted from the COZY mailing list. If you save 20 lb. over contact layups, I'd be surprised. But we'll never know, because your plane is substantially different from other LE's. As I've said before, having done a lot of both types of layups, it seems like a lot of hassle for very little gain, but to each his own.

While I appreciate the offer, I am not an admin of any of the web-based canard fora, so don't need any help administering them.

Use techniques appropriate for the job. Most things are bagged, but most things are carbon and in molds, too. We use contact layups when appropriate.

Only if you do an exceptionally poor job of squeegeeing in the standard methodology. If you think that it's not possible to get air bubbles, voids, delams, or bridges when vacuum bagging, you're seriously deluding yourself. Bag if you want, but it's hardly the be-all and end all of composite construction.

See: http://www.roughriver.org/activities.html There's a lot of stuff to do at the state park/lodge. Mammoth Caves is a long way away by car.

1) When you guys do your stress analysis, to what tolerance are you performing your mesh sensitivity analysis to? 2) What's your mesh size? 3) How are you applying boundary conditions and loads? 4) You do realize that anodizing can significantly reduce the fatigue life of aluminum?

No. First of all, unlike your diagram, the canard (front wing) is always at a higher incidence angle than the main (rear) wing, or else the aircraft will not have pitch stability. Second of all, the canard creates a downwash, the magnitude of which grows as the AOA increases, but the since the relative positions of the canard and main wing (strakes, in this case) change as the aircrafts incidence angle increases, the relationship between the effective downwash from the canard on the strakes is a very complex one. At any rate, the downwash from the canard decreases the effective AOA on the strake area, decreasing the lift produced. Generally, that's not a good thing, and the relative positions of the canard/main wing/strakes have been set to minimize any negative effect. This is one reason why moving the canard either up or down from it's plans position is not a good idea.

Of course there are. Do Mazda rotary engined cars have engine failures less often than piston powered cars? It can't be argued that it's not less simple, in the sense of having fewer moving parts, but from a failure rate standpoint (which, of course, is only ONE of the factors used in choosing an engine), the argument is hardly clear in either direction. Big deal. I've had electronic ignition failures that didn't keep me from continuing a 5 hour flight from OSH to PVC (and which took an hour to fix). My vacuum pump could roll over dead and not stop the engine from running. I could name 5 things on my Lycoming, and 5 things on your rotary, which could stop the engine dead at any time. And would be on the same order of likelyhood of occurring. Using John's airplane, which has flown a total of less than 100 hours in approximately 4 years, as a positive example of anything is myopic at best. I fly 120 hours/year, and could fly a lot more (if I had places to go, and the time to do it). Nick Ugolini puts 300-400 hours/year on his LE. Please find me a couple of rotary engine aircraft (canards, preferably), which fly that much. You may be "certain", but you have no evidence on which to base this certainty. It's a belief, not a fact. There is, of course, no sense in arguing religion with a fanatic. No, you've made your mind up already, and facts no longer affect what you believe. Similar to the canopy hinging "debate". You pick and choose a small subset of facts from the overall pool, while ignoring any that detract from your existing belief structure. Use the rotary - clearly it can be made to work reasonably - Perry Mick has shown that, as have a very few others (in canards). However, since Ron Gowan, Joe Hull, Bulent Aliev, and Greg Richter have all removed rotary engines from their canard aircraft and replaced them with something else (3 of 4 with Lycomings), and the extant flying canards with rotaries are fewer than those that HAD them and got rid of them (I can now only think of Perry, John, S., and one more in South Carolina which flew a few hours and is still not out of Phase I after 4 years), and average far less time/year than aircraft with Lycoming engines, it seems clear that any supposed advantage is ephemeral at best.

In some sense, yes - fewer moving parts is more "elegant", from an engineering standpoint. But by that measure, a single transistor is more "elegant" than a 2 million gate CPU, but it's hardly as useful :-). It's not a turbine, though, as it still uses the Otto cycle, rather than the Brayton cycle. The inefficiencies have to do with the large sealing are, imperfect combustion chamber shape, and incomplete burning and concomitant high exhaust temperatures, rather than the cycle used. That was my point - if the advantage is in the elimination of parts that almost never fail anyway, and the histogram of failures indicates that the part that you still HAVE to have are the ones that fail, then you really haven't gained anything. There's no real weight savings, there's no real fuel savings, and by the time you get through with it, there's not a great deal of cost savings, either. I wish I was wrong. Well, I've seen him in his Long-EZ at OSH the last few years (with a Lycoming) and at the Marysville fly-in this year. For whatever reasons, they have chosen to go back to a standard aircraft engine. My point was not that Lycomings are "better" than rotaries - only that it's not obvious that rotaries are "better" than Lycomings. And unlike me, there are those who've had no issues with their Lycomings :-). But one data point does not a trend make :-).

What is there to "get"? While in theory, lower parts count may reduce failure rates, the data does not support the notion that rotary engines have failure rates any lower than any other engines. There's nothing to "get". If you like rotary engines, that's fine - they seem to work well in aircraft, if you don't mind having to search for mogas (especially out west) and having slightly higher fuel burns than aircraft engines, but the implication that you will have fewer failures due to the parts count (and moving parts count) is not born out by the epidemiological data. Before swapping it out for a Lycoming, as Joe Hull and Bulent Aliev are doing with their COZY's.

Because it's a lot more work for a relatively small weight savings. Probably on the order of 10-20 lb. total on a whole plane. Contact layups are a lot simpler, and don't require the equipment and extra materials (cost).

I fly everywhere, anywhere, whenever I want, with no restrictions based on the experimental nature of the aircraft. I fly through any airspace, at any altitude, that any other aircraft can. I work on, upgrade, and fix my own plane, at a total cost of ~$75/hr (that's for EVERYTHING - gas, oil, engine rebuild fund, depreciation, hangar, insurance, maintenance, etc.) and go 200 mph doing it. I don't need an A&P/IA. Ignorance is fixable - stupidity is not. If you are going to build/fly a COZY, you should join the COZY mailing list.

Yes. No. What mechanism could they possibly use to do that? Unless I'm in Class B, C, or D airspace, I don't even have to have my radio turned on. In any part 91 GA plane - not just experimentals. I've never had ATC give a crap about the fact that I'm an experimental, other than to ask what a COZY is.

During the Phase I flight test, there are restrictions imposed by the Op. Limits. In Phase II (normal operating), there are no different restrictions than for any aircraft. Common misconception, but completely untrue. I can (and do) fly anywhere that any small aircraft can legally fly.

Captain Bread Head? What are you, oblivious to popular culture? That's "Powdered Toast Man!" http://en.wikipedia.org/wiki/Powdered_Toast_Man Apparently, PTM flies backwards, hence the association with canards.

That's not my understanding. I believe it was done to lower the wing's moment coefficient.

I just noticed this post, and it could be extremely misleading, if not dangerous. While the COZY and Long-EZ RONCZ AIRFOIL exterior shapes are identical, chordwise, the cutout for the spar cap (and hence the spar cap itself) is NOT identical. The spar cap cutout on the COZY is deeper. While using the COZY cutout on a Long-EZ would merely cause it to weigh more than it should due to extra material in the cap (and a depression that would need filling, if using the plans spar cap fill), using the Long-EZ cutout for the COZY would lead to an understrength/understiffness canard, and would not allow the appropriate amount of cap material to be put in. I hope that you're using different templates for the two aircraft when cutting the cores, and not shipping Long-EZ cores to COZY builders, and vice-versa.

***Plonk***