Marc Zeitlin

Hard as it may be to believe in something that involves the safety of yourself and anyone else you put in the plane, "cool" is absolutely meaningless. Being a "kid" does not absolve one from considerations of safety. This is one of the two things you're right about - TBO of certificated turbine engines is far higher than TBO of certificated piston engines. Non-certificated for either - who knows. While true, what are the consequenses? If you end up going faster than the Vne of the aircraft, what happens? If you end up going faster than the critical mach number of the canard, what happens? Do you know? If you would say that, then you don't know what you're talking about. For equal power/thrust output, the turbine's efficiency is on the order of 2/3 of the equivalent power piston engine. It will use at least 50% more fuel to perform the same task. You will vastly lower your time aloft and range. Anything you would have gained by going faster you'll lose in the fuel stop that the piston engine doesn't have to make, and they'll get there a lot cheaper, too.

Folks: As a two week reminder, here is the information on the two fora at OSHKOSH that I'm hosting. Mark your calenders, and don't forget the rotten tomatoes. The "COZY Forum" will be held on Friday, 7/27/2007 at 1:00 PM in tent 02 - the "GAMA Pavilion". Here's the currently planned schedule: 1) COZY video produced for Aircraft Spruce - the world premier! Paul Drexler/Burrall Sanders 2) An overview of the COZY history, safety record, construction, modifications, etc. Marc J. Zeitlin 3) A Stretched, O-540 powered, retractable gear COZY MKIV Chris Esselstyn 4) Q&A The "Rutan Derivative Canard Forum" will be held on Thursday, 7/26/2007 at 2:30 PM in tent 06 - the "Sportys Pavilion". Here's the schedule: 1) CSA Introduction - Terry Schubert 2) Stagger-EZ Design - Steve Wright 3) E-Racer Blended Winglet Modification Marc J. Zeitlin/Jack Morrison 4) Propeller Loss Story - Marc J. Zeitlin 5) Q&A A listing of all OSHKOSH forums can be viewed at: http://www.airventure.org/forums/

The COZY mailing list archives are chock full of discussions on this subject. See: http://www.maddyhome.com/cozysrch/

AAAGGGHHH. Please read the myriad explanations that have been written on the mailing lists as well as the canard fora on the definition of the "Major Portion Rule". There is no such thing as a 51% rule. The MPR has nothing to do with how many people work on the plane, or in what sequence. Rick Maddy's project can ABSOLUTELY be certificated in the experimental amateur built category, and it's even likely that a subsequent builder could get the repairman's certificate. As long as the project was built for "recreation and education" any plans built aircraft will meet the MPR.

Folks: After much hard work on the part of Mark Forss at the EAA, I (as well as the other 1400 [if I understood Mark correctly] presenters) now have a schedule for both of the fora at OSHKOSH 2007 - mark your calendars. The "COZY Forum" will be held on Friday, 7/27/2007 at 1:00 PM in tent 02 - the "GAMA Pavilion". The title, as last year, is "COZY MKIV Aircraft - Soup to Nuts". I expect to give a slightly shortened presentation from last year - an overview of the COZY history, safety record, construction, modifications, etc. If we're lucky, we'll have the full version of a COZY video being produced for Aircraft Spruce, and if Chris Esselstyn provides a presentation regarding his modified O-540 retractable gear COZY, they we'll hear that too. The "Rutan Derivative Canard Forum" will be held on Thursday, 7/26/2007 at 2:30 PM in tent 06 - the "Sportys Pavilion". I have a TENTATIVE list of presenters: these include Bill Allen, speaking on his Long-EZ Cross Atlantic Flight; Terry Schubert, with an introduction to the Central States Association; Steve Wright, with a description of his award winning "Stagger-EZ" aircraft; Me, with a discussion of my propeller loss, and if time allows, further presentations on my belleville washer installation, as well as a possible presentation on Jack Morrison's E-Racer winglet modifications. Time constraints and whether people have the time to prepare will determine what's included. There will, of course, be a Q&A session at the end of each forum. A PRELIMINARY list of the fora I'm hosting is on the web at: http://www.airventure.org/forums/presenter.asp?EventID=12&PresenterID=1584 I think we'll have some good stuff here!

Way too thick. It's 7 plies of UNI and 2 of BID, for a total thickness of 0.089". Call it 0.09", or 3/32" if you like fractions.

Since the VE carries about 25 gallons of fuel, and with an O-200 burns at most 6 gallons/hour (usually closer to 4.5-5) at 140 kts or better, you've already got more than 600 NM range. You don't need extra tanks. Gary Hertzler gets over 45 NM/gal with his VE - his range is around 1KNM.

See: http://www.cozybuilders.org/newsletters/suppliers.html

Yes. No. Yeah, that was the logical conclusion to the original claim regarding the MAGNITUDE of the thrust - all you'd need is something to get you started, and then the winglets push you through the air :-). At any rate, there IS more thrust than drag, so the net effect is a small forward force, but it IS small. Also remember that symmetric airfoils DO produce lift, else aircraft with them couldn't fly. They just do so at different AOA's and with more drag than non-symmetric airfoils.

Yeah. I must have missed that statement in Andy's original message to the COZY mailing list, or else I would have said something about it, too. I sent Andy an email last night regarding that sentence, because some "cursory calculations" of my own indicated that it had to be incorrect. Here's Andy's (whittled down) response: "The simple fact is: I blew a few numbers on that original post." An honest response. Clearly, the winglets do NOT provide anywhere near the amount of thrust that would affect take-off (or any other segment of flight, either). For a LE/COZY, it's almost lost in the noise. Andy also mentioned that there were a few minor issues with his original post, but that this claim was the big error.

One would assume that with a properly designed CS prop, the takeoff #'s would improve, yes. I have a fixed pitch prop, optimized for cruise. A fixed pitch prop optimized for climb would also improve these #'s. Landing won't be perceptibly different from a roll standpoint, although putting a CS prop in flat pitch at low throttle setting will increase the descent angle (more drag).

As a followup to the COZY performance questions, I flew today for an hour. I took off and landed twice. I was solo, full fuel, for a Gross Weight of ~1650 lb. The takeoff at Tehachapi, DA=5000 ft., took approximately 1500-1600 ft. When I landed at Camarillo, DA=~1000 ft., I used about 2500 ft. of runway, because I didn't feel like stomping the brakes - I could have turned off 700-1000 ft earlier if I felt like it. I indicated 90 mph on short final (78 kts). and touched down at about 75 - 80 mph. The takeoff at Camarillo, same DA, took about 1100 ft. (30 lb. lighter, due to 1/2 hour of fuel burn). The landing at Tehachapi took about 2000 ft. This should help put things in perspective. Obviously, forward CG's and heavier weights will decrease performance and require longer runways. But unless you're going to be in the air for 5 hours, you don't need full fuel, and you can arrange the aircraft to have the CG as far back as possible.

You've mentioned this guy before, and it always struck me that he's clueless and flies his aircraft completely incorrectly. No wonder he needs long runways - I float a mile if I come in that fast. That's totally absurd. Nonsense. Solo, lightweight, you're off the ground in 1/2 the runway. Landing is no problem whatsoever - I'd have no compunction at all about flying in there, even relatively heavy (although probably not at MGW, but 3 folks and 1/2 fuel would NOT be a problem). Possible, but unlikely. Absolutely. Doubtful. You've been fed a line by someone that doesn't know their ass from a hole in the ground, and that's the only datapoint you've got. There are folks in the US that fly their canards way too fast on landing too, although I've never heard anyone say they approach at anywhere near 110 kts. If you're still interested in the COZY, stop by the next time you're in the US, anywhere near LA, and I'll be happy to demo the plane CORRECTLY for you. If I make it to RR this year (I'm hoping to) I'll be happy to show you the performance of the COZY off of a 3K ft. runway. MGW, full forward CG will require more than 2500 ft - I'd use 3K ft as a minimum at std day SL. But MGW REAR CG would probably be doable. But unless you're going for a 800 NM flight with 3 large folks (two of them VERY large in the front), you'll never be at MGW full forward CG. While that's certainly not the optimum airport for a COZY, as indicated they're doable. You'd need to think about the situation, and you'd probably need to ensure a rearward CG and 1/2 fuel, but that's hardly a showstopper, if the OTHER performance of the plane is what you want.

SOME of the layup schedules are the same, and some are NOT. The spar caps and shear webs are NOT the same. This is critical. What reports would those be? My dead stock COZY (aerodynamically and structurally) stall speed, at mid-weights and mid-CG, is about 72 MPH, or 62 KTS. At 2150 lb. and full forward CG, the stall speed is about 80 mph, or 69 kts. Solo, with light fuel loads, it's about 65 mph, or 56 kts. Hardly 80 kts. They tested Mark Beduhn's plane, which, unless I'm mistaken, has the short canard, NOT the longer, original one. The fact that X-plane predicts something that's outside of it's capabilities to do is a meaningless factoid, at best. COZY's do NOT stall at 80 kts in 1G flight. Since your premise is incorrect, your conclusions are incorrect also. Only using your erroneous figures. Talk to folks that fly Lancairs and Glasairs - ask them what their approach/touchdown speeds are - they're higher than the COZY, and that's because their wing loading is higher. The Glasair III touches down at my approach speeds. First of all, as far as real world experience goes, folks that fly LE's and COZY's fly them at almost exactly the same approach and landing speeds. The LE might be a bit slower, but it's not significantly so. The VE is at least as fast on approach and landing as the COZY, due to wing loading. With respect to your red herring about 4000 ft. runways, I operate out of a 4000 ft runway that's at 4000 ft. elevation. I've taken off of this runway at Max Gross weight on a hotter than standard day - DA was about 5000 - 5500 ft. It wasn't pretty, but it worked. I've taken off from 2400 ft. fields on 80 F days at mid-weights at SL, and been off the ground in 1200 ft. I can land in less than 1500 ft. at SL, and less than 4000 ft. at 10K ft. DA. Even an almost MGW takeoff at 10K ft. DA used about 5000 - 5500 ft. of runway - hardly a daily occurrance. I'm starting to believe that, as Dennis Passey does, you harbor some sort of pathological dislike for the COZY design. It's NOT perfect - not by any means - I've had uncountable arguments with Nat regarding possible improvements, and there certainly are improvements to be made. But it's not necessary to spread falsehoods about the aircraft in order to have discussions about the tradeoffs that were made during the design process, nor to discuss the possible improvements to the aircraft.

How do you really feel about Ken's plane, Jon? :-).

You must have some special form of mathematics with which I'm unfamiliar. Even using 2E-6 for carbon, 8-2=6E-6 for the fiberglass/carbon differential (7, if you use 1E-6 for carbon), whereas you get 13-8=5E-6 for the fiberglass/aluminum differential. Closer numbers is better (less is more) - you'd like the CTE's to be the same to minimize thermally induced stresses. The point is that carbon is certainly no better, with a fiberglass substrate, than aluminum, and probably a bit worse. Of course, since no aluminum hinge on a VE, LE, COZY, etc. has ever come off due to thermal issues, the whole argument is silly. I was pointing out that one of your rationales for carbinge usage is not correct. The rest may or may not be.

That's nice. Let's look a the #'s: 6061 Aluminum CTE: ~13 x 10^-6 in/in/deg F Carbon CTE: ~1-2 x 10^-6 in/in/deg F Fiberglass CTE: ~8 x 10^-6 in/in/deg F So, you tell me, which is closer to fiberglass - Carbon, or Aluminum? These are approximate, but there's clearly no major advantage to carbon over aluminum with respect to joining it to fiberglass from a CTE perspective, whatever the manufacturer of the carbinge says. Now, if you're joining it to carbon, then it's clearly better from a CTE perspective.

Unless the rest of your structure is carbon also, it won't. Carbon fiber has a thermal expansion coefficient close to zero. Aluminum's TCE is closer to glass fiber than carbon's is. You may like the carbinge for other reasons, but this won't be one of them.

Yep. Gave it a good swipe with 100 grit or so to rough up the surface. Hard shelling is good for breaking up large layups, like the wing skins, so that one person can do them solo without taking 12 hours. Micro one day, sanding and glassing the next. You can also do a lot of contouring before the glass goes on, so it can be a bit easier to get the fibers straight. Not a real big deal, though. I know that many folks don't like it, and it's certainly not good for every situation nor a panacea, but there are times where it can be a useful technique.

I performed hardshelling on hotwired foam. I then laid up glass over it. I also laid up glass with wet micro on hotwired foam. I let them both cure. In both cases, when peeling the glass off of the foam, the micro/foam interface failed, NOT the glass/micro interface. So, whether the glass/micro interface is as strong in a hard-shelled layup as in a wet layup or not wass immaterial for the epoxy I was using (Safety Poxy and/or equivalent) - the micro/foam joint fails first because it's the weak link in either case. Also, even if the glass/micro interface did fail first in a hard-shelled layup in a peel test, I'd contend that it wouldn't be a big deal. In any layup where you've got micro under the glass, the surface area is relatively large and the layup is NEVER in peel - it will always be in shear. How's that?

Not true. Do you have test results showing there's a problem with hard-shelling?

While MGS is better than some of the other epoxies, smell and danger are not necessarily correlated. There ARE organic vapors, and with NO ventilation, you should be wearing OV masks on any reasonably long layups and should change the filters regularly. Will you have problems if you don't? Probably not - most folks don't. But protecting yourself from a systemic allergic reaction is important - you don't want to be one of the few that gets one. Yeah, well, you don't want to use either one of those guys as poster children for safety concerns. Mike does stuff with epoxy and acetone that makes me cringe, and I've told him so :-). They've been lucky. Others have not been, and have had to stop building because of it, or worse, have had severe medical issues.

While he's having fun, he should protect himself by wearing long sleeve shirts and better gloves (if those aren't nitrile - NO latex). He should also be wearing organic vapor masks during layups, unless you've got VERY good ventilation and air turnover. I assume you'd like him to make it well past 15, or at least if he doesn't, have it be YOU that does the taking out, not the epoxy :-).

If you think these plans are imprecise and "loose", you should take a look at what the state of the art was before Rutan started producing plans for aircraft. These are two orders of magnitude better.

Yes, in a LE, with the battery in the nose, you MIGHT want the heavier battery if you also need ballast to be ahead of the rearmost CG. Do a W&B before deciding - you should fly as close to the rearmost CG (103" for a LE, 102" for a COZY MKIV) as you can for speed, fuel efficiency, and shorter rotation/landings. Since most LE's have only one pilot, it should be easy to tailor the ballast weight to put the CG exactly where you want it for almost all flights.