Flying Ladders?

Discussion in 'The light stuff area' started by Cy V, Dec 17, 2009.

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  1. Oct 13, 2010 #41

    autoreply

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    Well, so you're using one design to "prove" that composites suck. Wow.

    I guess you didn't notice that 90% of the homebuilts and roughly 100% of the certified craft have a separate spar.

    Testing isn't necessary during production and neither are metal spars tested. Why not? Because they all fall within 1-2% of the design specifications. After 10-20 years of real-life operation and thousands of hours, unlike aluminium by the way, that does fatigue...
    Well, just another point where you're ill-informed. Glass first flew in the sixties. In production. Carbon first flew in the early seventies in a structural role (spar). From 78 it was used in production, for certified aircraft in the majority of the produced sailplanes. Over 3 decades of operational use. In very humid conditions (geez, seen our climate?). Some have over 10K hours. And those have been tested. Fatigue is not noticable, unless there's been flown without gelcoat for a considerable time.
    That you're basing your judgment about composites on two people who didn't turn out to have the specific knowledge (long term use in composites, specific to aviation), required for this discussion is fine. But well, it might be a good idea then to listen to people who actually do. All that "heard from this guy stuff" isn't even remotely linked to solid engineering.
    You were talking about carbon, not glass right?
    Well, that's the whole point. If you're building a carbon spar with the same weight, it could probably lift a King-Air. With pultruded carbon, one can build a spar in what, 4 hours?
    Because they suck, were way too stubborn and didn't listen to the advise of the actual experts?
    Making a carbon spar in multiple peaces is cursing the gods, but well, that's what happens when you take "hundreds of millions of dollars", accountants and not technicians take over....
     
  2. Oct 13, 2010 #42

    Bart

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    Again, this is a forum about ultralight aircraft under little regulatory scrutiny and typically built in a garage by amateurs who typically lack the training, skills, experience, or testing facilities of aerospace manufacturers.

    That said, even Boeing with its vast array of talent and resources, still has its problems, as seen recently in the 787 Dreamliner wing box, which then had to be redesigned at great expense and delay.

    Your explanation: "Because they suck, were way too stubborn and didn't listen to the advise of the actual experts? Making a carbon spar in multiple peaces is cursing the gods, but well, that's what happens when you take "hundreds of millions of dollars", accountants and not technicians take over...."

    Huh?

    If Boeing (arguably the best in the business) is still sorting this out, how is the typical ultralight amateur builder to do proper quality control at some reasonable cost and time?

    That is why, after my own initial fascination with composites, I have a healthy skepticism. As you know, composites have fabulous engineering potential, if done right. Sadly, despite best efforts of many amateur homebuilders, doing it right may be beyond their capacity, even if the designer and parts supplies acted with perfection, although they often don't act with perfection. Dead people are the result.

    You say: "If you're building a carbon spar with the same weight, it could probably lift a King-Air. With pultruded carbon, one can build a spar in what, 4 hours?"

    An amateur ultralight homebuilder can build a pultruded carbon spar in 4 hours, ready for at least a simple sandbag static test? Please educate me on this. Also, please contribute your expertise on resins of various sorts that are suitable for homebuilder use.
     
  3. Oct 13, 2010 #43

    autoreply

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    Well, quit talking about Boeing then:
    The failure of "arguably the best in the business" while several competitors have vastly smaller (or non at all) problems shows that that very statement might be wrong. Very wrong. The world is bigger as that single company....

    Shall we now quit about anything, not related to our subject please?
    It looks like you only know the Rutan method (foam, sand/hotwire, glass). That's indeed messy, but there are many methods and (fortunately for us), most of the methods, used by industry are within reach for us homebuilders.
    Well, the 4 hours aren't strictly true, since the stuff has to cure, but "in-hand time" is something alike. Graphlite (with connections to Jim Marske) is what we're looking for and for example, the LAK manufacturer is using those as well, in their certified aircraft. Extremely light and vastly superior to handmade spars.
    I prefer to use stuff that's proven. Just use the same epoxies as the sailplane manufacturers use for decades and companies like Cirrus and Columbia/Cessna use. For high-temperatures (dark-colored), take a look at what Lancair uses, but be prepared to pay hefty for an oven.

    As for their construction; you have carbon rods with a given strength, which you basically can't screw up, unless you break them, so so far it's pretty simple, calculate, test one (to verify) and you're done.

    As for a spar, there're several lay-outs, with either a separate shear-web where the rods are glued onto, or a foam shearweb, that's used as the sandwich filler and the male mold. This way, you build a spar from a strip of foam, glue the rods to it and wrap it in epoxied glass (the shear web, holding the rods together as well).

    Only a couple of things are critical:
    *Buckling strength of the shear web (as in metal)
    *Glue strength between shear web and spar cap (as in metal)
    *If wrapped around the rods, the modules of elasticity of the material should be lower (via fiber orientation or material properties), because otherwise it takes most of the loads. CF as shear web will do just fine, unless unidirectional.

    Here's a good read about it:
    http://www.homebuiltairplanes.com/f...spar-design-shear-web-spar-cap-interface.html

    And just to give you an idea; for my new design (1000 lbs, 10G ultimate, 21 ft span) I'm looking at a total rod weight of several hundred grams, let's say less then a pound.
     
    Last edited: Oct 13, 2010
  4. Oct 13, 2010 #44

    Topaz

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    And here's your answer:

    Boeing is working on cutting-edge applications. Nobody had ever done that kind of structure with that type of attachment in composites before. In fact, one could argue that trying to duplicate a metal-style structure in composites was a contributing factor to that issue. Some developmental problems were bound to crop up. The real problem in the 787's case was their compressed development schedule, which didn't allow for adequate testing to progress until the final full article was constructed. Their management wanted to develop a completely new-technology airplane in less time than it took the team to develop one of the earlier ones using more conventional technologies.

    Now, you seem to think the 787 wing-box issue is some kind of strike against composite aircraft. As if a metal structure would never have seen this kind of difficulty. The C-17 military airlifter - built entirely of metal - suffered a wing structural failure in static testing. The wing buckled and collapsed at far less than the ultimate load factor.

    By your logic, that means we don't have metal structures figured out, either.

    So which is it? Does a failure in testing indicate unequivocably that a given materials technology is suspect or not? You can't have it both ways. If you're condemning composite structures for this kind of developmental problem, then metal is equally suspect.
     
    Last edited: Oct 13, 2010
  5. Oct 13, 2010 #45

    Topaz

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    Spare me your condescending attitude. It's inappropriate in this forum.

    Tell me some things Rutan missed, specifically, and also please tell me your personal qualifications to make that judgement.

    Please explain to me how you can accurately test a metal wing without first putting it together. I'm quite familair with RAF builder's manuals, marketing, and designs. Rutan never made that promise. He did say that you could build the basic structure of one of his wings in a weekend, and that's absolutely true.

    Stop. You're exaggerating. Hugely. The RAF builder's manuals contain complete inspection and construction criteria, referenced throughout the process. The only builder who would be "oblivious to such problems" would be one that didn't read the builder's manual. There are also clear post-construction inspection criteria laid out, both for the builder and the FAA inspector/designee.

    You're being deceitful in how you're portraying this. If you really helped build an EZ or one of the other aircraft mentioned, you know there are inspection criteria supplied. Please stick to facts.

    This is a canard. It's also pretty hard to load-test an aluminum structure when it's still sheet stock rolled up on the spool. Nice try, but no.

    No, this forum is about homebuilt aircraft. Ultralights are a subset of that group, but are talking about all categories and classes of homebuilts, from ultralights to multi-engine amphibs.

    Except that even your French guy has abandoned ladders in favor of regular aircraft-style tubes. Even he thinks it's not worth pursuing.
     
    Last edited: Oct 13, 2010
  6. Oct 13, 2010 #46

    Topaz

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    I think Autoreply and myself have already adequately demonstrated that this argument does not apply. And again, the all-metal C-17 wing had to be redesigned as well, at great expense and delay. So what you think you prove by talking about the 787, I really don't know.

    Because the homebuilder isn't engaged in a cutting-edge development program, but rather is building a previously-tested design to established inspection criteria. As I mentioned above, complete quality control and inspection criteria have been a part of RAF (and other) aircraft builder's manuals from the beginning. Did you not read them when you were working on your friend's EZ?

    Really. Please justify this grandiose statement of yours with some supporting facts. Please show me all these VariEZs, LongEZs, Glasairs, Lancairs, etc. that are falling from the sky. If homebuilder's can't build safe aerostructures in composites, how is it that all these people have managed to do it? I've flown a LongEZ. It wasn't falling apart, believe me. You'll need to demonstrate that composite homebuilt aircraft have a significantly higher crash rate when compared to equivalent-class/performance aircraft built of some other material, and you'll need to show that the increased crash rate is directly attributable to structural failure due to the material and methods used for construction.

    You've got no argument at all until you can invalidate the current in-service history of aircraft built this way.

    Now, how ANY of this is some sort of argument supporting the use of Home Depot ladders in aircraft construction is beyond me. You've gone off on a tangent here, and somehow seem to think that damning composites makes a good argument for using a hardware-store ladder as a primary structural component of an aircraft. Can we PLEASE get back on-topic?
     
    Last edited: Oct 13, 2010
  7. Oct 13, 2010 #47

    Bart

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    I agree, let's get back on topic,* which on this website is entitled:

    "The light stuff area If your plane weighs less than you do, this is your area! Re: Flying Ladders?"

    Post #15 discusses flying ladders with comments by somebody who has actually done some hands-on testing of this idea. I hope he will contribute his latest thoughts and findings. Why not resume discussion with post #15?

    I have read the French flying ladder community has moved to using extruded aluminum tubes like those of ladders, after ladder company lawyers expressed liability concerns, although the original ladder planes still seem OK. Further, per posts on the Oshkosh 365 website, reportedly the little ladder planes have a good safety record so far, and that French ultralights may be subject to more regulatory scrutiny than US ultralights. The language barrier has reportedly been a problem.

    So, back to aluminum flying ladders, anyone?




    *We can discuss merits and suitability for amateur homebuilt use of various materials and building techniques in other forums such as new technology or composites. Lots of things to discuss, but this thread concerns flying ladders of extruded aluminum.
     
  8. Oct 13, 2010 #48

    autoreply

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    Well, if I get it correctly, you were looking at them because it was simple, "almost ready" to test and I guess also less work to actually build them in a wing. For me that shouts Graphlite, since I think it meets all of your criteria! ;)

    On another topic, if you have problems with French text/explantation, don't hesitate to PM. I'm pretty fluent in it and as for my English, judge yourself :speechles
     
  9. Oct 13, 2010 #49

    BBerson

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    Most ladders are 3" extruded channel beams. The shape is quite good for a spar but normally 3" is to small for a spar. It probably is easier to use a stock airplane extrusion of 4" or 5" depth. I think a company called Carlson sells these spar extrusions for ultralights or light planes.
     
  10. Oct 14, 2010 #50

    Bart

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    Yes, it's simple and from what I have read so far, quite a few of these little homebuilt planes are already flying in France, reportedly with good safety and reliability. But, you are in Netherlands and speak French, no? Your English is obviously excellent, so I am sure we all would appreciate it if you would read the French flying ladder websites and tell us what is happening with the people who know these planes best.

    Graphlite would surely be stronger for a given weight. Also much more expensive. What happens when a hammer is dropped accidentally on Graphlite, or it falls on the shop floor? In other words, how tough is it, and how well does it take damage? We have been using aluminum for many years, and knowledge of it is fairly common, but not so much about graphite.

    Alex Strojnik's books discuss the common aircraft materials, comparative cost, weight, ease of fabrication, thermal and chemical compatibility, availability, etc.. He points out that even though materials like carbon fiber would be marginally lighter than aluminum for a wing spar, it is vastly more expensive, and you still have temperature and attachment problems perhaps beyond the capacity of the typical homebuilder. Basically, Strojnik went with aluminum for some things like his tail boom and spar, plywood for others, and fiberglass for others, using each to its greatest advantage. That makes sense to me.

    The ladders used in the French design pictures appear to be ~1" X 3" extruded rectangular cross section, so are closed unlike C channel. Being enclosed, maybe the insides could be used for fuel storage, as aluminum is compatible with fuel. If so, some fuel could be carried in the spars, and excellent place from a weight and balance standpoint.

    Also, speaking of weight and balance, study the pictures and see how the rear wing ladder is attached to the fuselage ladder: How simple is that? How easy it would be to move the wing forward or aft if weight and balance in the finished plane required. Other than the balsa gliders we threw as kids, this has to be about the simplest design there is. Look how easily the landing gear attaches, and the engine. There is nothing in this design to prevent enclosing the fuselage for better streamlining and weather protection. If you like Leggos or erector sets, this plane seems for you.

    The question of ladder quality has been raised. Surely, there are ladders from poor to excellent quality, made of extruded aluminum of known size, weight, and strength. In this area, excellent aircraft and marine quality aluminum extrusions are available, since Boeing and Alcoa are here, and are very reasonably priced.

    Surely, a lighter plane can be made of graphlite, but how much lighter and how much more expensive? Can a homebuilder working part-time in his garage make as good a graphlite plane as an aluminum one? Please tell us more about graphlite.

    Too bad Alex Strojnik, Stan Hall, Tony Bengelis, Molt Taylor, and others are gone now. It would be great to hear their perspective on this.

    Years ago, I was on the plastics/carbon fiber/epoxy bandwagon, and had a chance to talk with Molt Taylor at Oshkosh and Tony Bengelis in Austin. These guys knew a LOT about practical aircraft design and construction, and preferred materials with known (to them) characteristics. Neither was too impressed with plastics, maybe because they became old pilots because they were cautious. People who grew up with carbon fiber are probably comfortable with that.
     
  11. Oct 15, 2010 #51

    charles

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    this is a genius design !it has the square hole design for extra loads.503 rotax and blueboard foam,fabric and im drooling down the runway.:ban:
     
  12. Oct 15, 2010 #52

    autoreply

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    Well, if you want to know any specifics, just let me know :)
    Well, carbon is certainly more sensitive to impact damage, compared to alu/steel. Sometimes though that's exaggerated a bit:
    [video=youtube;7dtk818WSiU]http://www.youtube.com/watch?v=7dtk818WSiU&feature=related[/video]
    My major problem with that is that you have a lot of stuff to thing about if you combine materials. Steel+carbon = galvanic corrosion. Wood+epoxy=moisture, alu+wood is moisture Also, the structure becomes much more complicated. For example if you "reinforce" a wooden spar with carbon rods (or alu strips for that matter), the carbon/alu will take all the loads and thus your design is actually weaker. By sticking to (mostly) one material you avoid most of those problems and it requires a lot less calculations and design, whether you build wood, steel frame, alu or composites.
    Well, my major problem (and of others) isn't so much that the material isn't strong enough (you can test for it), but that you don't know. Fatigue, stress concentrations and such are all unknown and that scares me a bit.
    That's of course highly dependant on your design. For an average 2-seater I'd say you can save several dozen pounds in the spar, or most of the spar weight, but that's kind of a loose statement if you don't have the specifics of the design. I calculated a total spar weight of under a kilogram, for something that's close in performance and dimensions to the formula 1 racers. Looking at the pictures, I think the Cassutt's spar weights what, 20-30 pounds or so?
    Well, that's highly dependent on many things, but in general I'd say yes. You do have to built a mold (which is pretty straightforward for a spar), but given that many people have done it, yes. The nice thing about graphlite is that it's ultimate quality, you cannot screw up. If laying conventional rovings in a mold, quality might vary quite a bit, dependent on the qualities of the builder.
    Those last two sentences are dead-one. I've never liked wooden aircraft, though they do just fine in theory and reality and while I've repaired and flown them without serious problems.
    On the other hand, pilots of the powered club were always suspicious of composites and they wouldn't trust their dog to it. I've grown up with composite gliders, have repaired them and seen those craft, 30 years old with thousands of hours on airframe, often flown about 20000 ft and in conditions, varying a couple times a day from -30 Fahrenheit to 100 F.

    So yeah, personal perspectives (despite the factual information) plays a big role, even for those that are well-informed :)
     
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  13. Oct 15, 2010 #53

    BBerson

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    They make fiberglass, wood, and aluminum ladders. Probably carbon fiber ladders will be next. In that case, I bet the pultruded beams would be stronger than a home layup.
     
  14. Oct 15, 2010 #54

    Bart

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    Thanks Autoreply and BBerson.

    Carbon surely has some wonderful characteristics, and I am looking forward to finding some of it of excellent quality, reliability, and at reasonable price.

    Aluminum of known dimensions, quality, and strength is available right now, and has been for decades. There are published tables telling us what to expect from an aluminum extrusion of given dimensions and grade, and ladder manufacturers surely use such information in making their various types of ladders. A cheap step ladder will not have he same quality and strength aluminum as a ladder made for fire departments to use rescuing people from tall buildings.

    Questions:

    1. Anybody here know of readily available carbon fiber pulltrusions in 15-20' length of ~3-4" square or rectangular cross section suitable for a wing spar on an ultralight plane? This would be a finished product with good factory quality control, just like buying an extruded aluminum piece of the same size, that can be shipped via UPS, etc..

    2. Anybody have recommendations pro or con about aluminum ladders available in North America that are like those used in the flying ladder as seen in post 51 above? In other words, who makes these things and where can I look at one?



    PS: Thanks for the kayak video, but I note that a small dead blow hammer with shot pellets inside was used, as this softens the blow, unlike a solid steel sledge hammer. Of interest for wing skins may be a material called Carbonlite, which is not actually carbon fiber but apparently a sort of polycarbonate sheet, uded by Eddyline Kayaks and thermoformed. They have a website with video showing basic thermoforming of this stuff, which is extremely tough. You can hit it with a real sledgehammer and it retains shape and most strength. I know because I have a sample of ~1/10" thick Carbonlite here and hit it full force with a real 8 lb. steel sledgehammer, two-handed overhead swing like chopping wood with an axe--no shattering or penetration. That's another topic.
     
  15. Oct 29, 2010 #55
  16. Oct 29, 2010 #56

    Bart

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    Thanks, Dick, that's great!

    Any idea about his ladders or aluminum tubes, such as dimensions, type aluminum, etc.?

    I am wondering about a boxwing or boxplane wing of ladders, or ladder-like construction.

    Also, especially detail of his rear wing attachment to the ladder fuselage.
     
  17. Sep 26, 2011 #57

    clanon

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    I'm going to use 4 ladders(2 * on each half wing) reinforced (drag and anti-drag;tension and compression and maybe tig weld) just because it is all i can buy.
    "I do what i can ; with what i have ;right here where i am"
     
  18. Oct 2, 2011 #58

    inventing_man

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    I bought a 40 footer for 100 bucks . Its made by Werner rated for 250 lbs.
     
  19. Oct 3, 2011 #59

    clanon

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    How wide are those ? and a'm sure round steps would be the best for strength.
    Does anybody think that would be good, tig welding ladders back to back(the seam i mean) plus riveting.?
     
  20. Oct 4, 2011 #60

    PaulS

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    Does a ladder actually have the beam strength for a 3G loading?
    I am an ex-heavy equipment mechanic and stength is a prime concern with me.
    The last four years of learning about airframes has been a challenge for me and the evolution of my design reflects that learning process.
    Paul
     

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