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关于航空木材

现附上一篇关于航空木材的文章，英文原版的，不知哪位大侠能翻译一下，供大家学习参考。谢谢！

[align=center][align=center][color=#000000][b][font=Arial][size=12pt]Aircraft Wood[/size][/font][/b][b][font=宋体][size=24pt][/size][/font][/b][/color][/align][/align][align=center][align=center][i][font=Arial][size=10pt][color=#000000]Sport Aviation[/color][/size][/font][/i][color=#000000][font=Arial][size=10pt] December, 1998
by Ron Alexander[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][align=left][align=left][color=#000000][font=Arial][size=10pt]From the very beginning of aviation wood has been used in aircraft construction. Early aircraft designers and builders often used ash or hickory. They were looking for a type of wood that would be relatively lightweight in addition to being very strong. Just prior to World War I, Sitka Spruce was discovered by aircraft builders and found to be very well suited to their needs. The strength to weight ratio was discovered to be very favorable for aircraft use. Several other types of wood had similar strength to weight ratios but were not as easily harvested or as plentiful. At the time, spruce proved to be the best choice, not only because of the physical characteristics, but of equal importance was the fact that spruce was readily available and easy to use as a building material. With the advantages noted, spruce became very widely accepted as the primary material to be used in building an airplane.[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][align=left][align=left][color=#000000][font=Arial][size=10pt]With the advent of World War II, spruce became even more popular. Manufacturers used the material in the construction of a large number of aircraft. Wooden spars were fabricated from spruce in many airplanes along with ribs and other structural parts. Because of the high demand for both aircraft production and for spruce to be used as a major material in manufacturing parts, forests of this popular wood were rapidly depleted. The use of Sitka Spruce was carried into post-war construction in many aircraft. The maintenance and restoration process of existing aircraft required a large supply of wood. Wood was a popular choice for aircraft construction because of its advantageous strength to weight ratio, workability, abundance, and low cost. The largest plane ever constructed—the Spruce Goose—is largely comprised of spruce. During this time in aviation history spruce was cheaper than aluminum or steel.[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][align=left][align=left][color=#000000][font=Arial][size=10pt]Today spruce and other types of wood remain somewhat popular for aircraft construction. Many aircraft designers and kit manufacturers within the sport aviation industry use wood as a primary structure. If wood is not the primary structure it is almost sure to be found in some component part. Wood is not as strong as steel or aluminum however; the construction can be so designed that the necessary strength is achieved with corresponding savings in weight. Many designers prefer to use wooden spars in acrobatic aircraft because the wood will better withstand the bending loads imposed during aerobatics. Unlike metal, wood does not weaken from fatigue. This, of course, is an advantage to the aircraft builder. Wood is used in fabricating spars, building ribs, floorboards, instrument panels, wing tip bows, longerons and stringers, leading edges, etc. Wood is easily formed into shapes making it the obvious choice for wing tip bows, leading edges, and wing walkways. Woodworking is a skill that is easily learned by the novice who usually has a basic knowledge of wood construction and some of the necessary tools. Safety hazards are very evident unlike some of the other types of aircraft construction. You should also understand that making mistakes with wood could be costly. You cannot easily repair a piece of wood cut to the wrong dimensions. [/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][align=left][align=left][color=#000000][font=Arial][size=10pt]In this and subsequent articles, I will discuss the types of wood that can be used in aircraft construction, how to inspect the wood properly to insure it is safe to use, tools needed for woodworking, plywood and glues, basics of aircraft woodworking, and how to inspect wood in a completed aircraft.[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][align=left][align=left][color=#000000][b][font=Arial][size=10pt]SITKA[/size][/font][/b][b][font=Arial][size=10pt] SPRUCE[/size][/font][/b][/color][font=Arial][size=10pt]
[color=#000000]Spruce has long been recognized as the best type of wood to use in the construction of aircraft. It is the standard against which all other woods are judged. It has several characteristics that make it the best type of wood for an airplane. It is light in weight with a corresponding greater strength and toughness than is found in other woods. It is easily worked, uniform in texture, resistant to rotting, and has no odor. It can also be obtained in clear, straight-grained pieces having very few defects. This is possible because of the size of a mature spruce tree. Sitka Spruce is the preferred type of wood for aircraft construction. The name Sitka was derived from a town located not far from Juneau, Alaska. Sitka Spruce is found mainly along the Pacific Northwest, particularly along the Alaskan coast. (Most of the spruce forests have been depleted along the coast of the United States and Canada.) The trees grow best in a wet, moderate climate. They will rarely be found more than 50 miles from a coastline. Spruce trees typically grow close together and in so doing they must grow very tall and fast in order to obtain necessary sunlight. Because of this type of growth they usually have few, if any, branches except near the top of the tree. This facilitates the type of growth necessary to yield knot free lumber suitable for aircraft use. A spruce tree will grow to heights of 200 feet and higher with a diameter of 8 feet or more. A tree of this size will have taken 400 years or more to reach this dimension. A spruce tree will not yield usable aircraft lumber until it is at least 5 feet in diameter. Even with this size tree only 5% or less of the resulting lumber will be of the quality necessary for aircraft construction. With this in mind it is easy to understand why we often have a deficit in aircraft grade lumber. As I mentioned earlier, use of Sitka Spruce prior to and during World War II depleted large forests of the wood. [/color][/size][/font][font=宋体][size=12pt][/size][/font][/align][/align][align=left][align=left][color=#000000][font=Arial][size=10pt]The use of Sitka Spruce is certainly not limited to aircraft construction. As a matter of fact, the aircraft industry uses a very small percentage of the total spruce that is milled. The majority of spruce harvested is used for ladders, house construction, masts of sailboats, barrels, cabinets, sounding boards for organs and pianos, and other uses. The building and restoration of sport aircraft is a very insignificant market for the wood industry. To further complicate the issue, several forests of spruce are protected from cutting by environmental issues such as preserving the spotted owl. [/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][align=left][align=left][color=#000000][font=Arial][size=10pt]Lets look briefly at how a piece of aircraft grade spruce is milled and inspected prior to arriving at your front door. The trees are harvested by lumberjacks and sent to a sawmill. That mill in turn will cut the trees into smaller pieces known as "cants". These cants are usually 6-8 inches square and anywhere from 10 to 20 feet long. They are then placed on a barge for the trip from Alaska to Washington. When they arrive at the lumber mill in Washington or Oregon they are then cut down to smaller sizes for the uses discussed earlier. I am aware of only one or two mills located in the northwest that will set aside wood for aircraft use. These mills will try to find aircraft grade wood and accumulate enough over time to fill the orders of the aircraft suppliers. This can often take several months. Once they have accumulated enough wood they will kiln dry the wood and then cut it into the desired thickness and width. The wood is graded to a military specification by a certified lumber grader. That military specification is numbered 6073 and I will define it later in the article. [/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][align=left][align=left][color=#000000][font=Arial][size=10pt]The pieces of wood are then shipped to the aircraft supplier. They are typically sent in lengths of between 10-20 feet at a nominal width of 6 inches. The boards will be planed smooth on the flat surfaces and rough cut on the edges. A board cut in that manner is termed a S2S board meaning it has been surfaced on 2 sides. The nominal 6-inch width is a problem for the aircraft supplier and ultimately the aircraft builder. Nominal 6-inch width means the width may be slightly less than or greater than 6 inches. When you, as the builder, need a finished 6-inch spar for your aircraft the supplier may have difficulty providing that dimension. The nominal 6-inch width may only finish to slightly over 5 inches when the edges are cut smooth. Widths over 6 inches are scarce. Lengths over 14 feet are also scarce. A thickness over 1 inch is hard to find. Why? Because the wood must be free from defects and typically the larger the piece of wood the more likelihood of discovering a disqualifying defect. The bottom line—it is very difficult for an aircraft supplier to acquire high quality spruce in the dimensions needed for aircraft construction. [/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][align=left][align=left][color=#000000][font=Arial][size=10pt]When a company receives the wood from the lumber mill they in turn will cut the pieces into sizes ordered by their customers. Notice one very important point—absolutely no one has stamped this wood "aircraft quality". The mill does not certify the wood as aircraft quality nor does the aircraft supply company. Years ago some of the suppliers would stamp "aircraft certified" on pieces of wood. Not today! Forget about receiving wood that is certified for use in an airplane. The only grading that occurs at the mill is done to meet Mil-Spec-6073 but in no way will they tell you that the wood is aircraft quality. The aircraft supply company in turn will inspect the piece of wood they cut for you but they will not stamp it as aircraft certified. You are ultimately responsible to ensure that the piece of wood you are placing in your airplane is of the necessary quality to be used within the structure of your airplane. (We will discuss in detail how to inspect wood later in this series of articles.)[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][align=left][align=left][color=#000000][font=Arial][size=10pt]The sale of spruce is a nightmare for a supply company. The price they pay for shipments of spruce is very high. In addition, they have high costs in preparing the wood for shipment. The wood is very easily damaged when working with it or storing it. And finally, at least 40% of the wood they receive cannot be used for spar material. That means they must either cut the wood into smaller pieces to be sold as capstrips and longerons or burn them in their fireplace. Cutting the wood into smaller pieces is labor intensive. Even with the high price you will pay for a spruce spar the aircraft company is not making money. I was in that business for over 17 years and can personally attest to that fact. [/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][align=left][align=left][b][font=Arial][size=10pt][color=#000000]ALTERNATIVES TO SPRUCE[/color][/size][/font][/b][font=Arial][size=10pt]
[color=#000000]If Sitka Spruce is so difficult to obtain why not find alternatives? A valid question and certainly a number of alternatives to spruce do exist. First of all, lets look at what type of wood can be used to replace spruce within an aircraft structure. Understand that written information regarding the use of wood in aircraft is limited. The primary source of information for the builder may be obtained from FAA Advisory Circular 43-13, government bulletin ANC-19, and from a copy of Mil-Spec-6073. Advisory Circular 43-13 lists a number of different types of wood that may be used in an aircraft structure. Some of these are Douglas Fir, Noble Fir, Western Hemlock, White Pine, White Cedar, and Yellow Poplar. I will discuss the ones that are the most readily available—Douglas Fir, White Pine, and Western Hemlock.[/color][/size][/font][font=宋体][size=12pt][/size][/font][/align][/align][align=left][align=left][color=#000000][font=Arial][size=10pt]As noted in the comparison chart in Figure 1, Douglas Fir is a very acceptable alternative for spruce. Its strength exceeds spruce by roughly 23%. Advisory Circular 43-13 states that it may be used as a substitute for spruce in same sizes or slightly reduced sizes providing the reduction in size is substantiated. Fir does have a tendency to split making it somewhat more difficult to work. It is also heavier than spruce—about 26% heavier in fact. Remember, you are allowed to use a smaller dimension due to the increased strength. Years ago, a number of aircraft manufacturers would route out a portion of a fir spar to save weight. Boeing used that method on a number of PT-13 and PT-17 trainers. Can you purchase good Douglas Fir? Some lumberyards will have a good supply at a reasonable price. Most aircraft supply companies find it just as difficult to obtain Douglas Fir as they do Sitka Spruce. The cost from an aircraft supply company will be about the same. You may find Douglas Fir cheaper at a lumberyard. What about White Pine? As you can see from the chart White Pine is 85-96% as strong as spruce. It is easy to work with and is somewhat available. A number of kit manufacturers are using White Pine successfully within their designs. It is low in hardness and shock resisting capability. It cannot be used as a direct substitute for spruce without an increase in size to compensate for the lesser strength. [/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][align=left][align=left][color=#000000][font=Arial][size=10pt]Western Hemlock has been used in the construction of aircraft for a number of years. The popular Pietenpol airplane used Western Hemlock in constructing spars for a number of years. The strength properties slightly exceed spruce and the wood may be used as a direct substitute for spruce. FAA Advisory Circular 43-13 notes that it is less uniform in texture than spruce. [/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][align=left][align=left][font=Arial][size=10pt][color=#000000]Concerning the comparison chart in Figure 1, two definitions are in order. A ring per inch is a measure of the rate of diameter growth of a tree. These rings correspond closely to yearly increments of growth of the tree. See Figure 2. They are not necessarily definite criteria for strength. Mil-Spec-6073 defines the number of rings per inch needed for spruce that will be used in an aircraft structure. According to government bulletin ANC-19 – Wood Aircraft Inspection and Fabrication—it states "Rejection of material on the basis of the number of rings per inch is somewhat arbitrary, because it does not always reflect the strength of the piece." Maximum grain slope is the deviation of annual growth rings from parallelism with the longitudinal axis of a piece of wood. See Figure 3. Looking at the face of a board the growth rings should not slope upward or downward more than the specified amount, usually 1 inch in a 15-inch length of the wood. This slope of grain is usually termed diagonal grain. Both of these will be discussed in detail in the section pertaining to inspection of wood.[/color][/size][/font][font=宋体][size=12pt][/size][/font][/align][/align][align=center][align=center][color=#000000][b][font=Arial][size=10pt]CHART OF WOODS FOR AIRCRAFT USE[/size][/font][/b][font=宋体][size=12pt][/size][/font][/color][/align][/align][table=95%][tr][td=1,1,115][align=left][align=left][color=#000000][b][font=Arial][size=10pt]TYPE OF WOOD[/size][/font][/b][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,150][align=left][align=left][color=#000000][b][font=Arial][size=10pt]STRENGTH[/size][/font][/b][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,172][align=left][align=left][color=#000000][b][font=Arial][size=10pt]MINIMUM RINGS PER INCH[/size][/font][/b][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,160][align=left][align=left][color=#000000][b][font=Arial][size=10pt]MAXIMUM GRAIN SLOPE[/size][/font][/b][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][/tr][tr][td=1,1,115][align=left][align=left][color=#000000][font=Arial][size=10pt]Sitka[/size][/font][font=Arial][size=10pt] Spruce[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,150][align=left][align=left][color=#000000][font=Arial][size=10pt]100%[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,172][align=left][align=left][color=#000000][font=Arial][size=10pt]6[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,160][align=left][align=left][color=#000000][font=Arial][size=10pt]1:15[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][/tr][tr][td=1,1,115][align=left][align=left][color=#000000][font=Arial][size=10pt]Douglas Fir[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,150][align=left][align=left][color=#000000][font=Arial][size=10pt]Exceeds Spruce[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,172][align=left][align=left][color=#000000][font=Arial][size=10pt]8[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,160][align=left][align=left][color=#000000][font=Arial][size=10pt]1:15[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][/tr][tr][td=1,1,115][align=left][align=left][color=#000000][font=Arial][size=10pt]White Pine[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,150][align=left][align=left][color=#000000][font=Arial][size=10pt]85-96%[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,172][align=left][align=left][color=#000000][font=Arial][size=10pt]6[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,160][align=left][align=left][color=#000000][font=Arial][size=10pt]1:15[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][/tr][tr][td=1,1,115][align=left][align=left][color=#000000][font=Arial][size=10pt]Western Hemlock[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,150][align=left][align=left][color=#000000][font=Arial][size=10pt]Slightly exceeds spruce[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,172][align=left][align=left][color=#000000][font=Arial][size=10pt]6[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][td=1,1,160][align=left][align=left][color=#000000][font=Arial][size=10pt]1:15[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][/td][/tr][/table]
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[/b][b][font=Arial][size=10pt][color=#000000]INSPECTING WOOD FOR AIRCRAFT USE[/color][/size][/font][/b][font=Arial][size=10pt]
[color=#000000]If I cannot obtain spruce or any other wood that is certified for use on aircraft how do I know I have the correct quality? The answer is you don’t. You must find someone familiar with inspecting wood or learn more about it yourself. Now, there is certainly a difference between production aircraft and experimental aircraft concerning legalities. There is, however, no difference in concerns for high quality. [/color][/size][/font][font=宋体][size=12pt][/size][/font][/align][/align][align=left][align=left][color=#000000][font=Arial][size=10pt]Production aircraft must verify a source for all materials that are used as a replacement for original parts. That means very simply that you should be able to track the origin of the wood that you will be using to replace a spar in a production airplane, as an example. Since wood is not stamped "certified for aircraft use" what does the FAA want in the form of paperwork to verify you are placing the proper type of wood on your airplane? Most of the inspectors I have contacted agree that a copy of the grading certificate stating that the shipment of wood that included your spar material meets Mil-Spec-6073. As far as actually certifying the wood as being legal to be placed upon your airplane that is the responsibility of the A & P mechanic and ultimately the IA who returns the aircraft to service after the repair. Some companies will actually manufacture a spar for replacement on a certain type of airplane. This should be done using a PMA number (Parts Manufacturing Authority). That satisfies the requirement for origin of the part but it must still be inspected and authorized by the IA.[/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][align=left][align=left][color=#000000][font=Arial][size=10pt]As you are probably aware, the materials used in experimental aircraft do not have to meet any legal requirements. That does not exempt the builder from using common sense and good judgement. In other words, even though I do not have to verify the origin of the wood used in an experimental aircraft I will want to do so. I would strongly encourage the builder to thoroughly inspect the final piece of wood for defects prior to installation. Now, the builder of an experimental aircraft can go to a local lumber yard and purchase spruce, fir, or white pine. If you are purchasing spruce make sure it is Sitka Spruce. No grading certificate is required and usually cannot be obtained because an expert does not grade that wood. There is nothing wrong with purchasing wood from a lumberyard as long as you know what you are buying. In other words, you must become familiar with allowable defects and tolerances regarding the use of wood in aircraft. This will be accomplished by acquiring information through AC43-13, ANC-19, Mil-Spec-6073, etc. to ensure you know what is safe in your airplane. If you do not feel confident in performing this inspection, find someone who is knowledgeable concerning aircraft wood. [/size][/font][font=宋体][size=12pt][/size][/font][/color][/align][/align][font=Arial][size=10pt][color=#000000]In the next issue I will outline the proper procedure for identifying and inspecting wood for use in aircraft. This will help you familiarize yourself enough with the major defects to be able to identify them and know that the wood you are using is safe. I will be quoting largely from Mil-Spec-6073, a document that can be purchased through Aircraft Spruce & Specialty. The Forest Products Laboratory also has a wealth of information concerning wood in general. They have been very helpful to the EAA and to custom builders in general. Ben Owen and his group of knowledgeable people in Information Services at EAA Headquarters also have a lot of good information regarding aircraft wood. [/color][/size][/font]

只有一个简单问题，从哪里可以买到符合航空标准的“Sitka Spruce ”？

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这个网站不错，好东东真不少！ 看重这个空速表，配“大航模”合适

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云杉
【学名】Picea asperata Mast；spruce
【别名】粗枝云杉、大果云杉、粗皮云杉、白杆等；
【科属】松科，云杉属。属于针叶树的一类，通常有线条分明的年轮，与季节性山地气候保持一致.
【时代】侏罗纪—全新世；
【产地】云杉为中国特有树种，以华北山地分布为广，东北的小兴安岭等地也有分布。
【形态特征】常绿乔木，株高可达30米，树冠广圆锥形。我国有17种9个变种。多分布青海东部，甘肃南部和陕西西部海拔3200米以下。

【概述】

        松科(Pinaceae)云杉属的总称。 常绿乔木。树干端直。中国是云杉属植物最多的国家，共16种9变种，分布于东北、华北、西北、西南地区及台湾的山地及亚高山地带，尤以横断山地区种类最多，木材蓄积量丰富。云杉属植物最早的化石发现于美国西部及日本的晚白垩纪地层中。第三纪末至第四纪更新世因红皮云杉全球性气温下降的影响，使云杉从高纬度和高海拔地区向低纬度和低海拔地区扩展，种类增加。后随冰川的退缩和气温的回升，分布区又逐渐缩减，繁衍至今，形成了现代的分布格局。在中国秦岭以南及东南部的平原和西南部的低山地区的晚更新世沉积物中发现了云杉的花粉及球果。云杉为耐阴性较强的树种，喜寒冷与冷湿的气候，在高纬度的寒带、寒温带至低纬度的暖温带与亚热带的亚高山与高山的阴坡、半阴坡和谷地形成纯林，或与冷杉、落叶 松、铁杉和某些喜冷凉气候的松树及阔叶树组成针叶混交林或针阔混交林。云杉树干高大通直，节少，材质略轻柔，纹理直、均匀，结构细致，易加工，具有良好的共鸣性能。可供建筑、飞机、乐器（钢琴、提琴）、舟车、家具、器具、箱盒、刨制胶合板与薄木以及木纤维工业原料等用材。

        许多云杉树的特征具有下垂的枝，整颗树层层排列。直挺的针状叶呈螺旋形围绕着茎，长度为 2 ~ 3 厘米。叶从椿处长出来，如果脱落，椿便会保留下来。木质球果悬吊着，卵石形成圆柱形，有向内弯曲的苞片，当球果成熟时，这些苞片会张开以让种子脱落。云杉为高大乔木的针叶树种，高约45m，胸径lm，树冠为狭圆锥形，树皮灰色,呈鳞片状脱落，大枝平展，小枝上有毛，一年生枝黄褐色。叶四棱状条形，弯曲，呈粉状青绿色， 先端尖，四面有气孔线，叶长1~2cm，叶在枝上呈螺旋状排列。花单性，雌雄同株，5月开花，10月球果成熟，具有周期性结实现象，一般4-5年出现1次丰年，歉年的种子品质差，发芽率低。种子千粒重3.6-4.6克，每公斤种子250000-350000粒，发芽率20-45%。种子用麻袋普通干藏，2-3年后发芽率降低8-15%，低温密封干藏，5年发芽率只降低5%。

【种类及分布】  

        全世界云杉属约40种，分布于北半球。中国约有20种，分布于东北、华北、西北、西南以及台湾等地。根据叶形及气孔线情况可分为 3组，即云杉组、丽江云杉组和鱼鳞云杉组。云杉组叶横切面四方形、菱形，四面有气孔线，气孔线条数相等，或近相等，包括白皮云杉、鳞皮云杉、粗枝云杉、红皮云杉、白杆、青海云杉、雪岭云杉、新疆云杉、青杆、大果青杆、台湾云杉、长叶云杉等。丽江云杉组叶横切面近方形、菱形或扁平，叶上面每边的气孔线较下面多 1倍，叶下面无气孔线，包括丽江云杉、紫果云杉等。鱼鳞云杉组叶横切面扁平，下面无气孔线，上面有两条白粉气孔带，包括鱼鳞云杉、麦吊云杉、西藏云杉等。

主要树种有：

        白皮云杉(P. aurantiaca)树高达20米,胸径50厘米。中国特有树种，产于四川康定附近。垂直分布海拔为2600～3700米，以海拔3200～3400米为常见，多为散生，或与川西云杉、鳞皮云杉混交,数量不多。

        鳞皮云杉(P.retroflexa)树高45米,胸径达1米。中国特有树种,产于四川康定、雅江、新龙、丹巴、大金、小金、理县、茂汶、青海斑马等地。垂直分布海拔为2100～4100米。常与紫果云杉、川西云杉、岷江冷杉、紫果冷杉混生，或形成小片纯林。

        粗枝云杉 (P. asperata)树高达45米，胸径达1米。中国特有树种,产于陕西西南部、甘肃东部及白龙江流域和洮河流域、四川岷江流域上游和大小金川流域，海拔2400～3800米地带。常与紫果云杉、岷江冷杉、紫果冷杉混生，或成纯林。

        红皮云杉 (P.kor-aiensis)树高30米以上，胸径60～80厘米）。分布于中国东北大、小兴安岭，吉林山区，长白山区,辽宁昭乌达盟地区,内蒙古多伦及锡盟种畜场海拔 400～1800米地带。在东北常与红松、鱼鳞云杉、臭冷杉、、白桦、紫椴、色木、水曲柳等混生成林，间有成片纯林。朝鲜北部及苏联远东地区也有分布。

        白杆(P.meyeri)树高达30米，胸径60厘米。中国特有树种。产于山西（五台山区、管涔山区、关帝山）、河北（小五台山区、雾灵山区）、内蒙古西乌珠穆沁旗，垂直分布海拔为1600～2700米。常组成以白杆为主的针叶树阔叶树混交林，伴生树种有青杆、华北落叶松、臭冷杉、黑桦、红桦、白桦及山杨等。

        青海云杉(P.cras－sifolia)树高达23米，胸径30～60厘米。中国特有树种，产于祁连山区、青海（都兰以东西倾山以北）甘肃(河西走廊及靖远、榆中、夏河、卓尼、舟曲)宁夏（贺兰山、六盘山）、内蒙古大青山海拔1600～3800米地带 常在山谷和阴坡组成纯林。

        青杆(P.wilsonii )树高达50米,胸径1.3米。中国特有树种,产于内蒙古(多伦、大青山)、河北（小五台山、雾灵山）、 山西(五台山、管涔山、关帝山、霍山)、 陕西南部、湖北西部、甘肃中部及南部洮河与白龙江流域，青海东部、四川东北部及北部岷江流域上游等海拔1400～3000米地带，为国产云杉属中分布较广的树种之一，常成纯林或与其他阔叶树混生。

        大果青杆(P.neoveitchii)树高8～15米，胸径50厘米。中国特有树种，产于湖北西部、陕西南部、甘肃天水及白龙江流域海拔1300～2000米地带。散生于林中或生于岩缝,现此林木数量稀少,应加强保护和繁殖。

        新疆云杉(P.obovata)树高达35米,胸径60厘米。分布于新疆阿尔泰山西北部及东南部海拔1200～1800米，常在河谷两岸形成带状纯林，或在阴坡下部与新疆落叶松混生。苏联、蒙古也有分布。

        雪岭云杉(P.schrenkiana)树高35～40米，胸径70～100厘米。在新疆天山及昆仑山西部均有分布，常形成纯林。台湾云杉(P.morrisonicola)树高达60米，胸径可达1米以上。中国特有树种，产于台湾省中央山脉海拔2500～3000米地带。常组成或单纯林。

        长叶云杉 （P.smithiana）树高达60米,胸径达1米以上。分布于西藏南部吉隆等地海拔2400～3200米地带。自尼泊尔向西至阿富海拔2300～3600米地带也有分布。常组成混交林或纯林。

        丽江云杉(P.likianensis)树高达65米,胸径达2.6米。产于云南西北部,四川西南部,垂直分布海拔为2500～4000米。组成纯林或与其他针叶树组成混交林。川西云杉(P.likianensis var.balfouriana)树高达40米，胸径达1米。产于四川西部和西北部、青海南部、西藏东部,垂直分布海拔3000～4000米。多组成大面积纯林或与其他针叶树组成混交林。

        康定云杉(P.likiangensis var.montigena)，中国特有树种，但数量稀少，产于四川西部康定折多山海拔3300米以上地带。

        黄果云杉(P.likianensis var.hir-tella)产于四川西部巴郎山、康定大炮山及九龙、西藏东部类乌齐等地，海拔3000～4000米地带。混生于川西云杉林中。

        林芝云杉(P.likia-nensis var. linzhiensis) 树高达50米,胸径70～100厘米。产于西藏东南部、 云南西北部、 四川西部海拔2900～3700米。组成纯林或与其他针叶树混生。

        紫果云杉(P.purpurea)，树高达50米,胸径达1米。中国特有树种，产于四川的阿坝藏族自治州地区，经夹金山而延伸至贡嘎山西坡，甘肃榆中及洮河流域、青海西倾山北坡，垂直分布海拔2600～4000米。能组成纯林或与岷江冷杉、云杉红杉等针叶树混生成林。

        鱼鳞云杉( P.-jezoensis var.microsperma)树高达50米,胸径可达1.5米。分布于东北大兴安岭至小兴安岭南端及松花江流域中下游。海拔为300～800米。常与红皮云杉、臭冷杉、红松、蒙古栎、白桦、核桃楸等混生成林，或间有小片纯林。苏联远东地区、日本北海道也有分布。

        长白鱼鳞云杉(P.jezoensis var.komarovii)树高20～40米,胸径达 1米，产于吉林东部及南部山区海拔 600～1800米地带。常组成针叶林或针叶树、阔叶树混交林，常见的伴生树种有臭冷杉、杉松、红皮云杉、红松、岳桦、白桦、水曲柳、蒙古栎、色木槭等。朝鲜、苏联也有分布。

        麦吊云杉(P.brachytyla)树高30米，胸径达 1米。中国特有树种，产于湖北西部、陕西东南部、四川东北部、北部及岷江流域上游、甘肃南部白龙江流域，生于海拔1300～3200米，常与青杆、云杉、铁杉、冷杉混交或散生于针阔叶混交林中。

        油麦吊云杉( P.brachytyla- var.complanata)树高达40米，胸径可达1米以上。中国特有树种，产于云南西北部、四川西部及西南部（松潘以东、汶川、宝兴、洪雅、峨眉、峨边、马边、雷波、金阳以西）、西藏东南部，海拔2000～3800米地带。在四川西部常生于、铁杉、云南铁杉为主的针叶树混交林中，或在局部地带形成小片纯林。在云南则与云南铁杉、丽江云杉等树种混生或成小面积纯林

        西藏云杉 (P.spinulosa)树高达60米，胸径可达 1米以上。产于西藏南部（亚东、吉隆等地），海拔2900～3600米。不丹、锡金、尼泊尔也有分布。常组成纯林或与其他针叶树阔叶树混生。

        此外，在中国引种栽培欧洲云杉(P.－abies)和日本云杉 (P.polita),前者在江西庐山及山东青岛生长良好。后者在山东青岛、浙江杭州、四川理县米亚罗等地生长一般。

北美云杉特性介绍
北美云杉令人印象深刻，它所以产出的木材也同样如此。在世界上所有的树种中，北美云杉具有最高的强度重量比。具有很好的韧性恢复力的弹性，能够承受突加的荷载。由于北美云杉的较窄边材逐渐融入心材，没有明显的过渡，因而外观漂亮。木材的色泽范围从乳白色到略带淡粉色的白色，无嗅无味。
北美云杉因其优异的加工性能而成为著名的再加工用木材。它易于干燥，而且干燥后尺寸稳定，不易翘曲或扭曲。由于其纤维长、纹理直和质地软，所以北美云杉能很好的进行机械加工来满足精细公差要求且能牢固地握裹住各种紧固件。北美云杉易于刨光，刨光后的表面平滑、光亮、无开裂现象。同时，它能很好的吸收油漆和着色剂，由于其色泽均匀，所以所需的上漆次数少于其它多种木材，并且易于胶合。
由于强度重量比高和减震性能好，北美云杉被用于制造飞机和船舶而闻名。可制作船桅杆、吊杆、横杆和结构龙骨等。由于其具有极好的强度而不增加过多的重量，被广泛用于从单人赛艇到近海快艇等各种赛艇。特别适用于作船桨。
北美云杉的强度，轻度和极好的弹性恢复力使其成为制作梯子的上佳木材之一。同时，其良好的加工性能，成为制作室内饰面和滑动屏风等特殊细木工产品时倍受推崇的木材品种。由于北美云松具有较长的木纤维、绝佳的共鸣、稳定的尺寸和良好的胶合性能，所以它常被用来制作优质乐器共鸣板。此外，它还是声誉颇佳的建筑用材。由于它能经受风吹雨打且变形均匀，不易开裂，所以被经常用来制作室外体育场的座椅。北美云杉和冷杉是家具，门窗，地板，钢琴音板及吉他，室内精细装修，镶板，桅杆，甲板横梁等理想的材料，同时由于其木质强度，硬度和密度都较大，也使得它们成为理想的建筑和工业用材。这些木材的颜色浅，无树脂，具有极好的机械加工性能，且纹理细而直，极好油漆和上色。由于质地细密对钉子和螺丝有着绝佳的钉着力。
用于胶合板单板旋切的松木、白杨、铁杉、花旗（道格拉斯）冷杉和云杉。这是做胶合板最高等级的木材，50%-60%的木材完全没有疤结，其他只有很少的小疤结。木材圆而匀称，比如2.7米长的木材，两端直径的差距不超过1.5厘米。

北美云杉的物理性质
表观密度430kg(kg/m3)
顺纹抗压强度37.8（MPa）
横纹抗压强度4.1(MPa)
抗弯强度69.5（MPa)
抗剪强度9.2（MPa)
劈裂强度38.0（MPa)

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俺在网络上查到福建莆田和山东枣庄有公司经销北美云杉，有如下2个问题：

1：不知上述2个公司进口的北美云杉是否能满足航空的要求？

2：国内生产的那些云杉是不是都不能与北美的云杉相比，不能满足航空的要求？

[[i] 本帖最后由 航模钢琴 于 2007-11-5 11:15 编辑 [/i]]

别的木头也可以，只是要做强度试验。世界上航空用的木头都以北美云杉的强度为标准，如果强度只有它的0.8，那么木条在设计时就应加粗20%。
航空等级的木头对纹路，树节，沙孔等等也有严格的要求。整棵北美云杉运到锯木厂，再精选，可做航空等级的木头不到10%！所以它很贵。
当然，你看象SKYPUP那架飞机没有用航空木头，不也飞起来了吗。只是在保证强度的前提下它会更重一些，寿命也会短一些吧。
可以让那两家给你寄点样品，我们来看看。

收下了。。
帮顶一个，，发家是个高手handshake.gif

请问航空木材和航空铝合金比强度那个高？相差多少？

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铝合金的强度是木头的三倍，但重量也是木头的三倍。故比强度几乎是一样的。但结构中的构件体积不能无限缩小，比如一根木头，按同等强度用铝合金材料时，粗细只需木头的三分之一，但在结构中你为了固定，连接，你不能采用很细，很薄的铝（螺丝等紧固件是有一定直径的），加上用比重很大的钢螺丝等进行连接。所以整个铝结构一定会比木头结构重，这是航空界早已验证过的了。当今很多比赛用的特技飞机的机翼还是采用全木头的，就是为了减轻重量，争取成绩。

木头，铝合金，钢材和复合材料各自的特性比较！

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[[i] 本帖最后由 太阳 于 2007-11-11 14:18 编辑 [/i]]

我个人觉得在国内的话还是选择合格的航空铝材比较好，毕竟质量多少有点保障，而国内的木材质量以及木材加工工艺和大家的胶活都很难得到保障，隐存的危险可能要远远大于铝材，你们说呢？不过我还是非常非常赞成象太阳一样买国外的成熟的套材进行DIY，虽然价格上会高很多，可是总比自己弄了改，改了再改，最后从头再做要好很多，不但浪费时间和金钱，总成本可能比买套件更高，国内有很多朋友都想发扬创新精神进行创造，不过我觉得我们自己的思路总不会有人家几十年的经验可靠，至少也要仿造人家几个以后有经验再创新，也应该象玩模型一样，先买，后仿，再创新！

我是农村长大的,在家时,发现桑树比其它的木材更能承受载何,有很好的弹性.用桑木制成的扁担很小,但能挑更重的东西.

桑木的确结实，但同等体积下，桑木要比云杉重吧。

smile0.gif smile0.gif 学习来了

用桑木做螺旋桨行不行？问一下，不知道有谁能告诉我

个人认为很多木材之所以不如云杉,主要的原因可能在木材的纹理吧,纹理不好的木材加工大点的物品,获得可预知的强度很不好搞

那黄杨树呢

不是黄杨扁担更好使吗?