Jump to content

adouglas

Members
  • Posts

    36
  • Joined

  • Last visited

Personal Information

  • Location (Public)
    Bridgeport, CT

Project/Build Information

  • Plane Type
    Cozy Mark IV
  • Plans/Kit Number
    1364
  • Chapter/Area
    0

adouglas's Achievements

Newbie

Newbie (1/14)

10

Reputation

  1. A while back I purchased one of those very rare items, a full set of mostly unused, unregistered LongEZ plans. They came with one airplane part: A main gear bow. I've come to the conclusion that I'm unlikely to ever actually do this project, and the bow is taking up space (not quite ready to off the plans, though... ). I'd like to get rid of the bow, but I REALLY don't want to ship it. The bow has had the mounting tabs fabricated and attached, but that's as far as the original builder got. If it were me, I'd grind 'em off and do them again, because they look pretty sloppy. But I might be wrong. I see no actual voids/resin lean areas or anything like that. I live in Connecticut near KBDR. Again, I'm really not interested in shipping this. I see that one of these has just sold for $250 plus shipping. To compensate for the inconvenience of not being willing to ship, I'm asking $200. I don't get on this forum much, so please email me adouglas (at) optonline (dot) net
  2. Actually, Wayne, I was referring to the shape of the plane (aerodynamics), not the structure. Not really the central point anyway.... Regarding the plans format: The plans books are 11 x 17. The drawings for the LongEZ are 18x24, and there are 14 of them. The supplemental plans for the LongEZ are a variety of sizes. RAF is closing its doors if it has not done so already. They are the source for the supplemental plans (e.g. Roncz canard, long rudders, internal bellhorns, etc.). These plans also are available on the RAF CD-ROM set, available from TERF or AS. Regarding copies: If you do some digging in the archives, you'll find cautionary tales about dimensional inaccuracies created by copiers. I believe that this is less of an issue with newer copiers than it once was. I recently bought a full set of LongEZ plans (complete with an unused license, even). They're so old that I fear the paper will start to disintegrate if I actually try to use them regularly, so I did some test copies on one of our machines at the office, and the proportions appear to be perfect. If you go with a Cozy, for 50 bucks Aircraft Spruce will sell you an extra set of the template drawings, which are in fact derived (where possible) from the DWG files on Marc's site. Worth the money. Lots of people just use tracing paper to make copies.
  3. Don't confuse form with content. A CAD system is nothing more than a really fancy pencil. CAD lets you produce nice-looking drawings easily. But that's it. It doesn't help you make the actual design any better. The engineering that went into the design of the EZ aircraft and the Cozy is plenty sophisticated. Exactly what, besides aesthetically pleasing drawings, would actually be accomplished by taking the existing plans and putting in a lot of effort to convert them to CAD? Sure, you could drive a CNC machine with the file and automate the cutting of parts (people HAVE done this), but in the real world how many of us have access to such equipment? The thousands of aircraft built using Burt and Nat's plans are living proof that the existing plans work just fine. A great many very fine aircraft were designed without the benefit of CAD. The drawings for them were all done by humans, using manual tools. Such as, hmmm...the SR-71. Oh, by the way: there are some CAD renderings of certain parts of the Cozy over on Marc Zeitlin's site. There have in fact been homebuilts with drawings that were prepared using CAD. The one that comes to mind is the Prescott Pusher. Don't recognize the name? Not surprising. It showed up in the mid-80s and faded pretty fast. CAD doesn't make the airplane any better.
  4. That NTSB report is a preliminary, not a factual report or statement of probable cause. Be that as it may, the witness said the airplane came out of clouds in an inverted flat spin and THEN the wing came off. ANY airplane will shed a wing if you overstress it beyond the design limits. The ceilings were at 900 feet. If he emerged from the clouds at 900 in an inverted flat spin, there's no way he was going to recover anyway (assuming he could). That airplane did not crash because of airframe failure (assuming there was not an additional failure that isn't in the preliminary report and assuming the witness account is accurate).
  5. If you're worried about impact damage, get a copy of the "building rutan composites" video (available from Aircraft Spruce, and worth the money) and watch Burt jumping up and down on a wing section. An aluminum wing section of the same weight failed catastrophically under the same treatment (it was Mike Melvill jumping on the aluminum piece, but he's smaller than Burt). I'm not an engineer, but I'm feeling in a Holiday Inn Express kind of mood this morning, so.... A point load on a composite skin can punch a hole or (more likely) cause a delamination, but consider that the composite structure is a true monococque...ALL of the skin carries load. So the loss of strength is minimal, no matter where the damage occurs. An aluminum structure is a semi-monococque...the skins between the ribs, spars, longerons, bulkheads, stringers, etc. do not carry most of the load...the underlying structure does (the skin does carry some load, hence "semi" monococque). The loads are transferred via the rivets. So an aluminum structure has a myriad of tiny stress concentrations around the rivets. Punch a hole in an aluminum airplane where there are no rivets, and you don't lose a whole lot of strength...but damage it where the rivets are, and you lose a LOT of strength.
  6. Not a builder myself (at least not yet), but here's what I do know: 1) If the airplane was properly painted in the first place, UV would never make it to the glass, much less the foam. 2) The foam in the wings (blue foam) is eaten by solvents, including gasoline. Given these two facts, it sounds more like the guy has a fuel tank leak. ANYTHING is repairable, AFAIK.
  7. The CD has everything BUT the templates. That includes high-performance rudder plans, landing brake, engine installation, Roncz canard, etc. Plus scans of all the CPs through 83 and the owner's manual. Plus the same for the VariEZE, Defiant, VariViggen and Solitaire. And the Moldless Composites instruction book. Yesterday I tried printing out a few pages of the Section 1 manual on 11x17 paper, and they came out reduced a bit. I don't think that's a printer artifact, but I'm not sure. Given that there are drawings in the books as well as on the templates, care should be taken to get the scale right if these files are used to actually fabricate anything. There are sufficient dimension callouts in the plans books to enable this to happen. For example, I'm looking at the landing gear chapter. On page 9-3 there are some full-size drawings of brackets. Radius dimensions are given that can easily be checked, and there are several holes that can be checked to see if they're actually circular.
  8. Take a photo of yourself, blow it up to life size, glue it to cardboard (like a movie theater lobby standee) and rig it so that the arms are animatronic (like those robot highway "flagmen"). Have it "sanding" your airplane...nobody will question why they see you sanding so much...after all, this is a glass airplane!
  9. Rich; If you have the ability and inclination, creating a builder-log website for your kit would be very useful to the community at large. I think the Aerocanard is more or less invisible simply because nobody's out there on the web with information like that provided by Slade, Zeitlin, etc. etc. etc. I have Cozy plans, but I do admit that the kit-built route appeals to me. That's a whole debate in itself that has already taken place...builders of plans-built airplanes argue that it's not a significant time saver, and they may be right. But I wonder...since they haven't built a kit-built airplane, how can they say for sure?
  10. That sort of thing is mere detail. There are many variations on methods. Think of it like a cooking video...it doesn't really matter what kind of knife, cookware or stove you use. The basics are the same. There are several different ways to skin the cat. What's far more important and valuable IMHO is getting an overview of the project and seeing how things go together.
  11. Old thread, I know, but I just queried Al at the "new" Aerocanard and he informed me that the videos are now available on DVD. Complete 10-DVD set for $150.00 plus $8 for S&H or $18 each plus $5 for S&H. I'd post purchase info, but I have a feeling that would violate forum rules. Go to the site and email him if you're interested. Having never seen one of these, I cannot comment on quality. While I agree that there's nothing quite like getting hands-on experience, and the websites are nice and detailed, a video presentation can give a really good overview of the process and help keep you oriented. I think video can be a very valuable learning tool. When you participate in plane day, what you get a lot of experience with is the part of the plane you're working on, and that's it. You may never even see other parts, either because they're in storage, they've already been installed and are no longer accessible or they haven't been built yet. When you visit a website, the information can be terribly confusing if it's not written clearly. Photos also...it's hard to look at a photo of an engine installation and make any sense at all out of what you see. But a video, with its changing point of view, is a lot easier to interpret.
  12. African or European? This stuff is IMPORTANT, man! Get with the program!
  13. Oh, I *know* it's been done (I said so earlier in the thread). I didn't mean to imply that it's impossible or even a bad idea. For all I know it's the greatest thing since the invention of the flight attendant. My point is that it's not a trivial endeavor, nor does it *automatically* mean the airplane is safer. Conventional light twins are safer than singles under some circumstances, but less safe under others. You can't have a Vmc rollover in a single. Every design change involves tradeoffs. Turning a single into a twin is no different. Great. We've got a TwinEZ (I actually knew that...don't recall where I've seen it before, though). Can it climb at gross with one engine out? What is its single engine service ceiling? What are its flight characteristics at low speed, with a full load and everything hanging out? Does it have to carry a ton of extra ballast to balance all that weight aft of the cg? What engineering was done on the structure to ensure that the new loads are carried safely? Was due diligence carried out, or was it "eyeball" engineered? Marc, as an engineer yourself you know full well how important this stuff can be. What flight testing has been done?
  14. It certainly can be, as you yourself point out in the very next sentence.... Right. There have been LOTS of Vmc rollovers in light twins. Many if not most designs are really marginal in this regard. I point out that turboprop twins generally don't have a climb/stall/Vmc problem because there is ample power on one engine to avoid problems when low, slow and draggy...their single-engine climb speeds are well above Vmc. Power loss in a piston twin is a really, REALLY big deal if there are controllability and/or climb issues in any part of the envelope with one engine out (most light piston twins fall into this category). The accident record speaks for itself. If having a second engine were a safety panacea, then piston twins would have a much lower accident rate than they do. The Starship is a unique case. The configuration certainly does work to reduce asymmetrical thrust, but as noted above the real key is having enough power to get yourself out of the Vmc trap. I'm no engineer, but it occurs to me that there are issues related to the structure of the aircraft in a typical light twin with engines on the wings, which is what I was referring to. You've got a lot of mass suspended well off the centerline, well forward of the spar, and far away from both the center of gravity and the center of lift. I'm sure a high speed film camera would show a twin wobbling and twisting in all sorts of interesting ways when it hits turbulence. Turn the whole thing backwards for a canard. Aerodynamically, if you lose one engine the airplane will be flying in a slip, with thrust off the centerline. The design may or may not treat this situation well. There are rudder authority issues and roll control issues. It's not as simple as just hanging another engine on the airplane. With a typical canard that has an independent rudder system, is it sufficiently powerful and robust to counteract asymmetrical thrust? I don't know. Do you? How much power can you apply in a given design before asymmetric thrust overcomes rudder authority and rolls the airplane over? The Starship configuration makes this less of a concern, but the phenomenon still exists and must be dealt with. :yikes: Say what? You think that completely altering the aft end of the airplane to accommodate a second powerplant is not significant? Not even Rutan himself would say such a thing, IMHO. The airframe was designed to hang one engine in the middle. That's what the structure is capable of handling. If you put two engines in some other location, you HAVE to redesign the structure to accommodate the new loads. This is not trivial! As I said I'm no engineer, but this is obvious to me. I agree. At least one person has already done it...that twin Suzuki with counterrotating props. It's no small task, though. I'd really like to find out what the actual performance of that airplane on one engine is. Can it climb at full gross on one engine? What if the landing brake is out? What's its single engine ceiling? If it meets the minimum requirements that all certificated light twins must adhere to, I'd be very impressed. For that matter, it MUST be awfully tail-heavy. Two engines, two engine mounts, two reduction drives, two props, two cooling systems (they're auto engines).... Just what is the weight and balance like on that airplane? Most if not all Cozys already have to carry extra weight in the nose during single-pilot operations. How much ballast does that airplane need? We already know that controllable pitch props are not used on canards as a rule because they represent a lot of weight well aft of the cg. How do you propose to handle that problem, doubled? Piston twins with non-feathering props have a great big drag problem in an engine-out scenario. It both kills climb AND increases asymmetric thrust. This isn't simple. My $0.02
  15. Well, auto engines are not necessarily less reliable than certificated aircraft engines...this is a point that is open to debate. If you look at the reliability record of auto engine conversions, it's pretty dismal. However, if you look closely at the record, I think you'll find that most of the time it's not the engine that is at fault...it's the supporting systems. In effect all of the auto conversion installations out there are prototypes...and prototypes ALWAYS have issues. So I think it would be fair to say that certificated engine installations as a whole are more reliable than auto engine installations, but I would not go so far as to say the engines themselves are more reliable. Regarding twins...Twins raise all sorts of issues of their own. With the exception of centerline thrust twins and strange one-offs like the South American guy who has two engines driving a counterrotating prop in his Cozy, piston twins have real handling and performance problems when one engine goes out. In certain circumstances (low, slow and heavy) a twin can be more dangerous than a single when an engine quits. Doubling the number of engines does not halve the chance of having a mechanical problem...it doubles it. There are twice as many points of failure. What the extra engine does for you is make that scenario more survivable most of the time (night, over water, mountainous terrain, etc.). Then there's the engineering involved. Light twins are more complex structurally and aerodynamically than are singles.
×
×
  • Create New...

Important Information