What elements are skis made of? Cross-country skis What 2 materials are skis made of?
WHERE?
QUALIFICATION?
With the exception of high school teams, there are very few other teams or clubs in America. Most skiers race as individuals, train and race with friends or alone. I used to participate in veteran competitions, but now the store takes too much time. That's why I ski just for fun (but we all do it for fun!). In addition, I was involved in cycling (as an athlete, coach, race director, and as a cyclist). I have a PhD in Cell Biology (University of Berkeley in California) backed by several years of chemical research.HOW DID THIS SITE APPEAR?
I opened the Sierra Nordic store in 1985. The website appeared 4 years ago. There are many visitors to the site, but we do not count them. We email subscribers weekly with updates including resort weather and snow conditions, technical advice and discussions about lubrication, tools, skiing, ski equipment reviews and more. We also plan to take orders via the Internet from next season. But most of our customers (from all over the country) either come to us or call us. "Sierra Nordic" is considered one of the best in the US among stores selling cross-country ski equipment. We only sell cross-country ski equipment, mostly free style and sell top models of classic skis.WHAT EXCEPT?
I also run a travel business called Alpine Adventure Tours - bike tours and cross-country ski tours. (See www.AlpineAdventureTours.com)We organize bike tours in France and Italy, as well as tours for cross-country skiers in Austria.
P.S. translator: At the end of his letters to me, Noel usually adds the phrase: "The secret of life is enjoying the passing of time." ("The secret of life is to enjoy the passage of time").
Alexander Vertyshev, translation editor
First, let's repeat what is known, so that when considering further information, we start from the most general principles and keep them in mind.
As the ski moves across the snow, the snow crystals melt at the point of contact with the skid, and the ski slides on a thin film of water at each point of contact.
SLIDING SURFACE (BASE).
All manufacturers of racing skis use hard sliding surfaces made of plastic with a high molecular weight. The hardness protects the base from aggressive snow, the porous structure allows it to absorb more lubricant. The plastic of modern skis is made from polyethylene with special additives (graphite, fluorocarbons), which polymerizes into a crystalline structure at high temperature and under pressure. This process is called sintering. Pores and regions filled with non-crystalline (amorphous) polyethylene and graphite particles remain between chemically and physically connected crystals. |
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LUBRICANTS.
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Conventional ski lubricants are made primarily from hydrocarbons. Hydrocarbon molecules look like long chains of carbon atoms. Several hydrogen atoms are attached to each carbon atom in such a chain, which is why such compounds are called hydrocarbons. Three types of hydrocarbons are used in modern ski lubricants, which, when mixed, produce conventional lubricants with different properties. These are paraffins, microcrystals and synthetic lubricants.
Paraffins
- These are relatively soft hydrocarbons, consisting of linear chains from 20 to 35 carbon atoms in length. They provide low coefficients of friction and glide well over snow crystals. However, paraffins do not have sufficient mechanical strength and collapse under pressure. are branched hydrocarbons containing from 25 to 50 carbon atoms. They have a higher coefficient of friction than paraffins, but are more plastic, resilient and therefore better able to withstand pressure. Paraffins and microcrystals are obtained from petroleum. They are the main components of ski lubricants.Lubricants designed for warm weather conditions consist of a mixture of soft paraffins and microcrystalline. They have a low coefficient of friction and glide easily over rounded snow crystals, repelling water better than solid lubricants. Cold snow, especially freshly fallen snow, consists of sharp crystals that easily penetrate the soft lubricant and slow down the ski. Therefore, cold snow lubricants contain paraffins and microcrystals with longer carbon chains. They are harder and therefore better resistant to the penetration of sharp snow crystals. - this is the third type of hydrocarbons used in the production of ski lubricants. They are slightly branched chains of carbon atoms, consisting of 50 or more atoms. They are very hard and brittle and are used as hardeners for paraffin waxes.
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Green START is a great example of a lubricant containing synthetic ingredients. Extremely cold snow lubricants protect the ski base by exfoliating as the snow penetrates. Synthetic lubricants also include polyethylene or "plastic" lubricants.
Soft paraffins are better absorbed into the pores and mixed with amorphous polyethylene. Solid synthetic and plastic lubricants are absorbed worse. But if you repeatedly apply soft paraffin, then after that solid lubricants will begin to be absorbed much easier, they will remain in the base and do not wear out longer. Starting with several coats of soft wax will ensure better penetration of the weather hard waxes.
In addition to hydrocarbon components, various additives are included in the composition of ski lubricants that improve their properties. Graphite additives in lubricants increase the content of graphite in the pores on the surface of the base. Metal oxides increase wear resistance. Fluorocarbons reduce friction and are excellent at repelling water and dirt.
The development of ski fluorocarbon lubricants began in the 80s. Fluorocarbons differ from hydrocarbons in that all hydrogen atoms are replaced in them by fluorine atoms. Fluorine has a dense layer of electrons around its nucleus and is the most electronegative element. The oxygen atom in the water molecule also has a dense layer of electrons. Fluorocarbon lubricants work well due to the mutual repulsion of fluorine and oxygen atoms. It is important to remember that fluorocarbons only repel liquid water. Cold snow contains less "free water" (fluid around snow crystals) than warm snow, so fluorocarbons work best on wet warm snow or cold snow with high humidity.
The first fluorocarbon used as an additive in ski lubricants was Teflon, (PTFE - polytetrafluoroethylene). In addition to its water repellency, Teflon is known as an excellent solid lubricant, having one of the lowest coefficients of friction known. Unfortunately, Teflon has low mechanical strength and does not withstand the effects of cold aggressive snow. In addition, the Teflon molecule consists of more than 500 carbon atoms, and therefore has a high melting point, much higher than polyethylene bases. So it cannot be used as traditional ski lubricants, fused into the pores of the sliding surface. It is mainly applied in surface lubricants or used in racing lubricants and additives, again remaining on the surface of the ski. Examples of such lubricants are Maxiglide (liquid, paste and powder), Swix F4, Ski-Go 280, Star C2.
In the late 1980s, ski lubricant companies began to use the organofluorine technology, originally developed for coating the bottom of boats and ships. Swix Cera-F was the first commercially available lubricant of its kind. Technically, such lubricants are known as perfluorocarbons, that is, hydrocarbons in which all hydrogen atoms are replaced by fluorine atoms. The length of a perfluorocarbon molecule does not exceed 20 carbon atoms, unlike Teflon. Due to their small molecular size, these lubricants have a low melting point and can be applied with an iron without damaging the base. (When you see the inscription 100% FLUOR, this means that the lubricant consists of pure fluorocarbons, not pure fluorine - Translator's note).
The advantage of organofluorine lubricants is their high water repellency, very low coefficient of friction, and their ability to repel dirt particles, which are mostly negatively charged. They are also good at repelling machine oil left behind by trail-rolling cars and waxy tree pollen. Therefore, such lubricants are especially good in the spring, when the snow becomes wet and dirty.
Unfortunately, the production of organofluorine compounds is very complex and expensive. There are only a few plants and laboratories in the world that produce these compounds from raw materials. Ski lubricant companies do not produce organofluorine themselves, but buy it from the same factories.
Like paraffins and Teflon, fluorocarbon lubricants also do not have sufficient mechanical strength, cold snow crystals easily penetrate them. Therefore, they brake at low temperatures and low humidity. The properties of fluorocarbons can be changed by changing the structure of the carbon chain of molecules. In addition, their percentage in the composition of the lubricant changes. This allows the development of fluorocarbon additives for different snow and temperature conditions, which explains the availability of various types of F-powders and accelerators on the market. In recent years, various structures of fluorocarbon lubricants have been developed, often incorporating atoms of other elements to increase mechanical strength and extend the temperature range. For example, the Italian company STAR has 8 different compositions of fluorocarbon lubricants (F1 - powder and briquette, F2 - powder and briquette, F3, accelerators of the DICE series - 3 types).
Every year, fewer ski manufacturers publish detailed information about the "stuffing" of skis in catalogs. It seems to be logical: few people think about what the ski has inside and how it affects the quality of skiing, and most importantly, the pleasure from it. But the point is also different: when creating modern skis, such a number of combinations of different materials are used that it is simply impossible for a non-specialist to understand what and how affects the design of skis. So let's just see what the skis have inside. Some, by the way, may even have “nothing”, like the unique Swiss skis ZAI Nessa.
But this is an exception to the rule. All leading manufacturers of alpine skis use similar technologies, the same materials and adhesives in the production. And as a result, skis of the same price category and destination behave identically. If you remove the recognizable coloring and logos from them, it’s not even easy to feel the difference, and even a very good specialist is unlikely to be able to distinguish a particular ski by its behavior from a number of others.
In fact, there are only two designs, if we ignore phrases like “unique patented technology”: cap and sandwich.
Cap- a bearing U-shaped profile, inside of which there is sometimes a wooden core, but most often - a foam filling. Due to its low cost in high-volume production, the cap + foam design is usually used in simple skis, for beginners and not very experienced skiers.
Sandwich- a wooden core, on top and bottom of which various layers are added or not added. There are also combined designs - a sandwich under the boots and a cap in the toe and heel areas, partially covering the side walls of a semi-cap, a torsion box (the core is wrapped in layers of fiberglass), a monocoque (a cap with a three-dimensional profile that sets the required characteristics), a sandwich with side walls, but these are already special cases or a combination of two basic structures.
The behavior of modern skis depends on every detail of the design. Yes, that's right: every element, every layer and every technology can greatly change the character of a ski.
Take, for example, the heart of a ski - wooden core. I think everyone knows that the best parquet is oak, because it is durable. But heavy. And a pine board floor will be much easier to handle, it is lighter, but it is enough to drop a hammer on it and a dent will appear. So the weight of the ski, and strength, and durability, and elasticity, and tenacity of the edges will depend on the wood of the core.
And since the requirements of different skiers for skis are different, the cores are made from different types of wood. Moreover, the boards are not taken from the nearest sawmill, but are made from trees growing in certified forests, so that the stability of the characteristics is maximum. The types of wood that are used for ski cores are poplar, beech, oak, ash, fir, pine, spruce, aspen... In search of the best (for virgin skis, for example) combinations of qualities, exotic varieties of wood are also used. For example, paulownia or Adam's wood is used, a lightweight wood with an excellent weight/strength ratio.
But the core is not made from a solid board. The dried boards are sawn into thin sheets, from which they are then glued into a puff cake, and it can consist of various types of wood. And then the resulting "pie" is sawn again, getting thin plates with a vertical set of thin wooden slats. So, glue is added to different types of wood already at this stage, the performance of skis also depends on the characteristics of which.
Why glue - sometimes grass is also used as a material for the core, that is, bamboo, ski cores are even made from basalt. Well, what: there were stone axes, ceramic knives have already taken root in the kitchen, why not stone skis? But still, wood remains the best material so far: the wooden core dampens vibrations well and ensures uniform deflection and elasticity of the ski along the entire length. Foam materials do not have this ability.
This is an illustration of different ski designs from a single manufacturer's collection. And so it is with all ski brands. There are also "complex" designs that are used in cases where it is necessary to reduce the rotational moment of the ski, that is, in models that are more likely to jump, swim in virgin soil and fly - in parks or on natural obstacles. In such models, to reduce the weight of the toe (and sometimes the heel), their design is made cellular.
On the sides of the core today you can often see side walls - vertical or inclined. They have several functions at once, one of the main ones is to protect the core from damage during side impacts and just when riding. Sidewalls appeared in ski construction not so long ago - as a reaction to carving and park skiing, which necessitated the creation of skis designed for increased edge loads. In addition to protection, the side walls also play another role: this type of construction is characterized by a more accurate transmission of forces when edging.
On the subject of materials and their influence on the characteristics of skis, you can write an entire encyclopedia. But it is enough to slightly change the thickness of the metal layer or the direction of fiberglass weaving, and the character of the ski will change. So it is better to leave this matter to specialists - after all, each manufacturer has its own secrets and its own technological subtleties and rules. Well, the three-dimensional construction in the next photo is another exception to the rule.
Core can be braided with fiberglass, and can be reinforced with layers of fiberglass from below and above. Instead of or in combination with fiberglass, layers of fibers made of carbon fiber or other materials, up to basalt, can be used. Yes, now fibrous materials are also made from stone.
Cross-country skis can be divided into three classes: these are professional racing (the so-called top or top model), amateur racing and touring skis. Recreational racing skis have the same geometry and skids as professional skis, but they use cheaper materials. This makes the ski heavier by 150 - 200 g, but the price is reduced by an average of $ 75 - $ 100 (almost twice). It should be noted that it is amateur racing skis that occupy the leading position in sales in the world.
Fisher RCS Carbonlite cross-country skis
If you are far from the idea of participating in skiing competitions and prefer a leisurely walk with your family through the winter forest, it is best to buy tourist skis. These are the cheapest skis (they are about three times cheaper than the top models). In addition, unlike racing skis, touring skis are wider, so they do not require a prepared track. True, it is worth saying that among the tourist models there are also expensive skis. On such skis they go along difficult and very difficult tracks - taiga, the North Pole.
KONEK OR CLASSIC?
Skiing can be done in two styles - skating and classic. The classic appeared before the skate (which reflects the name of the style), while the skis move parallel to each other. It is better to ride on a prepared ski track, although you can also move on fresh snow this way. Skating style came to skiing from skaters. This style requires a compacted run about three meters wide, as the skier skis as if skating, pushing off with the inside of the ski. Each style has different requirements for skis, so they are divided into skating and classic.
Outwardly, a skate ski can be distinguished by a blunt toe. Unlike the classical one, during the push with the foot, the skating ski should not completely touch the snow with the middle part (the required gap is 2 - 3 mm), otherwise it clings to the snow and the speed of movement drops. As practice shows, even among the best skis sometimes there are unsuccessful copies, so you need to check when buying a ski. Firstly, skis can be immediately rejected if their socks diverge during compression (for this, two skis must be connected with sliding surfaces and squeezed). Secondly, if the skis have a “stop”: they compress easily, but decompress poorly, and if you repeat the compression several times, then the block (the middle part of the ski under the mount) of the ski characteristically knocks. The remaining parameters of the skis are selected individually according to the weight of the skier. Although this can be done "by eye", many shops now have flexters (devices for determining the stiffness of skis) that allow you to do this more accurately.
Classic skis have a longer pointed toe. In addition, unlike skating, classic skis are softer. This is necessary so that during the push the ski completely touches the snow and the holding ointment “works”, and, accordingly, the ski does not slip back. On the other hand, a classic ski must be stiff enough so that during the glide, the holding ointment does not cling to the snow and does not slow down the skier. Classic skis have different block lengths and weight deflections, depending on what kind of snow they are intended for. For soft dry snow, the skis are softer, they have a long last (45 - 60 cm) and a more elastic front. For hard snow (old snow, plus temperature), skis are more rigid and have a short block (35 - 50 cm). In addition, there are also universal skis for any snow, but in general their speed characteristics are worse. Often skis are divided into "cold" and "warm". However, this division is not very relevant, since "cold" skis often ride well in warm weather and vice versa.
SIZE (LENGTH)
Skis are selected for each person individually, depending on his height. For the skating style, this is a height plus 10 - 15 cm, and for the classics - a height plus 20 - 25 cm. When buying tourist skis, it is better to focus on the classics, since it is easiest to go on an unprepared track with this particular style. But if you prefer to ski "mixed" style, then you can take shorter skis.
CHILDREN'S SKI
Skis for children differ from "adult" skis in that they are adapted specifically for fragile children's legs. They are usually wider and softer. In addition, it is desirable that the skis be strongly “fitted”, that is, narrower in width in the middle, since such skis are more stable when turning. When you buy skis for a child, be especially careful when choosing. Maybe your child will become a world champion, if only the wrong skis do not discourage sports. To prevent this from happening, skis (as well as boots and poles) must be the right size (do not buy anything for growth!). Particular attention should be paid to the rigidity of the skis: on too soft or too hard skis, the child simply will not be able to ride normally. If financial opportunities do not allow buying new children's skis every season, then it is better to buy used skis, or new skis, but from the last season, since they usually cost less.
HOW ARE THE SKIS MADE?
The ski has a sliding surface, “insides” and an outer surface.
The sliding surface of modern skis is made of plastic - high molecular weight polyethylene with various additives. If the “slippery” ski (especially for racing) has multi-colored inclusions in the form of granules, then it is better not to buy such skis, as this makes it very difficult, and often impossible, to prepare the skis well for racing or training.
The “insides” of skis are different not only for each class, but also for each manufacturer. For expensive racing skis, these are “honeycomb” technologies that have come from aircraft construction, and technologies that imitate wood (although real wood is a very good material, it is difficult to achieve stable parameters for a series of skis when using it). Some skis have wood inlays in the last, but this adds up ($50-$70) to the price.
In amateur racing and touring skis, the same (for example, honeycomb) technologies can be used with cheaper materials, or wood. But this is not just a piece of wood, these are specially selected and glued layers of wood with air channels between them.
For the manufacture of the outer surface of the skis, two technologies are used: “sandwich” (when the layers of the ski are closed on the side and top with plastic plates) and “Kap”, when the “innards” of the ski are pressed into the “case” (in this case, the sidewalls and the upper surface form a single whole). Outwardly, they differ in that the “sandwich” has an acute angle between the side and upper surface, and the “cap” has a smoothed one.
The cheapest skis, the so-called "semi-plastic" among the people, are made from an ordinary "piece" of wood. From wooden skis, which have already become a part of history, they differ only in the plastic sliding surface.
As a result of storage, the sliding surface of the skis is oxidized, therefore, after buying the skis, it is necessary to first cycle (that is, level the surface) and treat with ground paraffin. To do this, fill the "slipper" with melted paraffin for skis (in no case with a candle), and when it hardens, carefully remove the excess with a scraper (required to remove along the ski). At the same time, villi and dirt are removed, and the sliding properties of the surface are also improved. In addition, the paraffin-protected sliding surface will last much longer. If you are doing this procedure for the first time, in no case try it on your skis (especially racing ones), as they can be irreparably damaged. It is better to seek advice from an experienced person who can show you how to do it right.
It is also worth noting that now in almost any serious store they are trying to make life easier for the buyer (which is especially important for "dummies"), so for a fee you can make a preliminary preparation of the sliding surface immediately after purchase.
HOW OFTEN SHOULD THE SKI BE TREATED?
Purchased skis require constant care. Touring skis can be oiled and cycled once or twice a season, as they do not require high speed performance. How often you treat recreational racing skis depends on how often you ski. If you ski from time to time, then it is enough to treat your skis once a month, or with a sharp change in weather. For more serious skiing, especially professional skiing, you need to treat your skis before each ride. In general, there is a certain relationship between the quality of skis and the frequency of processing: the more expensive the plastic, the more often it must be processed.
SKI CARE: OINTMENTS, PARAFFINS, IRONS, SCRAPERS…
Recreational and touring skis often have special notches under the last, designed to prevent slippage. This, of course, degrades the speed characteristics of the ski, but at the same time, it alleviates the heavy burden of lubrication. Even if you do not grease them at all, they will still “behave” normally on the track.For professionals, ski waxing is a real art. Each athlete has his own preferences among ointments, powders and paraffins, as well as his own methods for treating the sliding surface of skis. Among the most famous brands are SWIX, REX, TOKO, START, RODE, STAR. Of course, there are domestic ointments (for example, Visti, Temp), but, unfortunately, their quality leaves much to be desired, so you should not use them for expensive skis.
Different ointments (as well as paraffins and powders) are designed for each weather. Very often, not only temperature conditions are indicated on the box, but also the method of application, which greatly facilitates ski lubrication for not very sophisticated skiers. General recommendations for lubrication are as follows. Skating skis are “smeared” equally along their entire length, and for classic skis, in order to avoid slipping, a holding ointment should be applied under the block (or designed for a temperature 2-4 degrees higher than the main ointment).
Paraffin or powder applied to a sliding surface is melted through paper or a napkin with a special iron: such irons differ from household ones in more uniform heating over the surface, more accurate temperature control, and also a “blunt” edge (household irons have a sharp edge). Although a specialized iron is quite expensive (about $ 70 - 80), if you are more or less professionally involved in sports, it is still better to “splurge” on such a device, since it is easier for them to “not burn through” the ski (roughness and hard blotches). To melt the ointments, it is better to use a special hair dryer, since in this case it melts more evenly. If possible, it is better not to use gasoline and gas burners (only in extreme cases when there is no access to electricity), since you can not only “burn through” the ski, but also ruin the plastic.
To level the sliding surface of the ski, special brushes, skins and polishing plugs are used.
Before re-greasing the ski, it is necessary to remove a layer of old wax (for hard waxes and powders, a scraper is used, and liquid waxes are removed with an iron). To clean the sliding surface of the ski from dirt, special washes are used. Use only branded products, as gasoline or turpentine spoils the microstructure of the sliding surface (whitish spots appear).
For lubrication, the ski is best placed on a special machine, since it is easier to make a uniform layer of ointment. Machines are collapsible (which is convenient in field conditions or with a lack of free space), or integrated into a special table. They can be either branded (for example, ATOMIC, FISCHER) or homemade. The only prerequisite for the machine is the rigidity of the ski. It is best to smear skis at room temperature. The room where you will do this must be well ventilated. Do not smoke while lubricating: nicotine and lubricant components can react, releasing toxic substances. If you use fluoride ointments and (especially!) powders, get a respirator - take care of your health!
WHAT HAZARDS LOOK FOR THE SKIER
A beginner skier can fall on level ground, so the skis should be wide and “fitted” (i.e. have a narrower middle in width), as this provides more stability in turns. Do not immediately go up the hill (even if it is very small): learn to ride on a flat surface first.
Be careful with sticks! Try to keep the handle of the stick in front of its point, and when rolling down the hill, hold the sticks under your arms (points back). Otherwise, you can “run into” a stick, which can result not only in serious injury, but also in a fatal outcome. This is due to the fact that with a heavy load, the stick can break and pierce the body with a sharp end.
When rolling downhill, squat a little and lean forward a little! This not only “softens” the unevenness of the slide, but also helps to avoid falls and, as a result, various injuries to the arms, legs, coccyx and head. If you feel that you are falling, do not "throw" the sticks forward (you can run into them) and do not sit back (you can beat off the coccyx), but try to gently "fall" on your side. This will help to avoid not only injuries, but also ski breakage. If you follow these tips, you can avoid major injuries. The rest depends on your accuracy and ability to ride.
Ski fans are proud that the famous polar explorer Fridtjof Nansen once stood at the origins of their sport, which is so popular today.
He wrote one of the first manuals on the downhill technique, advocated the organization of competitions for skiers. It was at the end of the last century.
What are skis made of?
Even then it became obvious that for skiing from the mountains you need skis of a special design. As for the raw materials for their manufacture, at first it was traditional - birch, ash, beech ...
Soon, however, even here the skiers broke with the tradition, giving particular preference to hickory, a genus of walnut. The most valuable property of its wood is that it practically does not get wet, does not absorb water.
This means that skis made of walnut will not warp after repeated contact with wet snow and melt water. Viscous and dense hickory wood also has enviable strength. And the high resistance to cracking makes it indispensable for the manufacture of skis.
Finally, for alpine skiing, often in contact with hard firn (snow, which, as a result of repeated recrystallization, turns into ice with sharp edges), the unsurpassed wear resistance of hickory is of paramount importance.
Wood or plastic?
The ski boom led to a sharp increase in demand for skiing. They began to buy on an unprecedented scale.
All over the world, there would hardly be as much suitable wood as needed to meet the needs of hundreds of thousands of ski fans.
A successful replacement for natural materials was found in the face of plastics.
It turned out that polyethylene is good for the lower, sliding surface of the skis, fiberglass for the outer layers, and foam plastics for the central wedge.
Although many firms engaged in the production of alpine skis, to this day, they still prefer the central wedges of solid wood, despite its high cost.
To give the skis special strength, individual layers began to be made of light alloys, and the lower edge, the so-called edging, was even made of steel.
To protect the upper layer from damage during impacts and ski-to-ski collisions, an obercant appeared on the upper edge - a narrow metal strip.
By taking these materials in various combinations, one can widely vary the properties of skis, select them according to the individual characteristics of the skier, and even in accordance with the characteristics of the track of a particular competition.
One of the most titled skiers, Jean-Claude Killy, often did just that.
The heavy responsibility of supervising the production of skis and then checking them for compliance with the specified requirements was taken on by one of Killy's associates in the French ski team.
Before almost every important competition, he conjured in the experimental workshop on several pairs of skis for his friend, and then picked up the lubricant of the sliding surface, making control descents.
According to the famous athlete, this painstaking rough work largely determined his success in competitions.
Alpine ski configuration and production
Mass production of alpine skis, of course, required a completely different approach.
It is more expedient to produce a whole range of skis with a variety of guaranteed properties than to make them individually for each athlete.
In addition, the structure of alpine skis and the technology for their manufacture have become so complex that handicraft workshops would no longer be able to cope with their release.
Now there are many options for the design of alpine skis.
However, a cursory, superficial glance is unlikely to catch this diversity - from the point of view of the external configuration, they all have a lot in common. Let's say they all taper somewhat in the middle.
This peculiar "waist" makes them more manageable in corners.
All of them are similar in features inherited from cross-country skis.
This, for example, is a weight deflection - the elevation of the middle part of the ski above the horizontal plane on which it rests.
It is needed so that the pressure created by the weight of the skier is evenly distributed along the entire length of the ski.
This is a tapering, highly curved toe and a slightly curved heel (here the skis are also very thinner; this shape of the toe and heel provides the least resistance to snow, and thinning gives the ski the flexibility necessary to overcome the unevenness of the track).
This is the groove on the sliding surface of the skis (along with their highly elongated shape, it is responsible for the stability of the movement).
All these signs are well-known, habitual. And yet, they are fraught with many problems.
It would seem that in order to give the toe and heel the best flexibility, they need to be made thinner. But this would mean a loss of strength.
Calculating the longitudinal section of a ski is not an easy task! Downhill skis are the most uniform in thickness - they require increased rigidity.
Fit skis
And the side contours of the ski? Any person more or less familiar with mechanics knows that stability and controllability are mutually exclusive qualities.
How, in such conditions, to calculate the fit of skis?
If they are intended for downhill skiing, where stability considerations come to the fore, they are fitted slightly.
The waist is narrower for giant slalom skis, and the narrowest is for skis for special slalom, which should be especially sensitive to the skier's control actions.
A highly curved ski toe is, as already mentioned, low snow resistance. But at the same time - considerable air resistance! As a solution to the dilemma, skis with an oval hole in the toe appeared.
Skis for figure skating from the mountains look very unusual: they barely reach the athlete's shoulder, do not have an internal groove on the sliding surface and ... are bent up both in front and behind.
By the way, about the length of skis: by this parameter you can clearly and unambiguously judge their purpose.
Skis for free skiing occupy the middle ground on the length scale.
They are long enough to provide even an inexperienced amateur with the necessary stability of movement, and, moreover, short enough to be easy to control, to facilitate the development of riding technique.
In addition, they are not very tough, and therefore, they “forgive” the mistakes of a beginner. The longest are sports skis for downhill, giant slalom and special slalom. The smallest length - skis for figure and acrobatic skating and coaching.
Internal structure
The feeling of obviousness with which the purpose of certain skis is manifested in their external parameters (such as length or fit) is completely lost when you get acquainted with their internal structure.
The variety of options here is truly endless. Each manufacturer strives to offer something of its own and advertises the next novelty as the optimal solution.
Here is a fiberglass profile of a complex box section with foam filling - it was chosen in order to increase rigidity.
Here is a ski with a metal central wedge of a honeycomb structure - this technique should prevent vibration of the skis.
At a high speed, which reaches 120-150 km / h during the descent, the ends of the skis begin to vibrate from impacts on the unevenness of the track, the contact of the ski with the snow surface is lost.
At the same time, it becomes more difficult to control the skis, and the risk to which the athlete is exposed increases. Unfortunately, effective measures to combat this phenomenon have not yet been found.
The manufacture of alpine skis, of whatever design, proceeds almost according to the same “scenario”.
Pasting plates smeared with polymer adhesive are applied to the central wedge.
A steel edging is laid along the lower edge of the ski.
The package assembled in this way enters the mold: gluing is carried out under pressure and at high temperature.
Skis, which are subject to special requirements for strength, are often also riveted along the edge with metal rivets.
The next step is to apply a decorative finish to the outer surface of the ski and mill the sliding surface to give it the desired profile.
The side surfaces of the ski are also milled. At the same time, adhesive streaks and burrs are removed.
Tests
The final operation is a comprehensive test of finished skis. Their results must be in accordance with accepted international standards.
So, the straightening load must strictly correspond to the length of the ski, the deflection of the toe under a load of 5 kg should lie within 23-28 mm, the heel - within 22-21 mm.
The natural oscillation frequency of the ski should be 10.5-11 hertz, moreover, these oscillations should decay in one to one and a half seconds.
During the tests, the skis are also subjected to forced oscillations with a frequency of 2 hertz: they must withstand five hundred thousand cycles without cracking, without losing the integrity of the fasteners and adhesive seams, without losing their shape (the limit of residual deformations is set to 10 millimeters).
Of course, skis are submitted for testing in pairs, and in each pair one ski should not differ noticeably from the other in terms of its performance. For example, when checking for elasticity, it is considered unacceptable if the deflection of one ski differs from the deflection of the other by more than 2 millimeters.
Only after passing all the control experiments, the skis are considered fit for that responsible and hard "work" for which they were created.
The devices that many generations of our ancestors used in Russia for moving on snow were created a very long time ago - several millennia ago. This need was dictated by the climatic conditions in which most of the country is located. It is almost impossible to move through deep snow without auxiliary devices. A person needed to get food at any time of the year, and it is very difficult to hunt without the ability to quickly move around the area.
Archaeological finds and research by scientists allow us to conclude that the invention of skis was ubiquitous among all northern peoples. The shape of the ancient skis does not quite correspond to the current concepts of this device. Some of them were oval or round and could not slide on the surface. Such skis were intended for stepping on snow. A pair could be used, in which the skis were of different lengths: one is short and wide, and the other is narrower and longer. With the help of the first they repelled, and on the second they glided.
Only one repulsion stick was used. A couple began to be used relatively recently - at the end of the nineteenth - beginning of the twentieth century. The sticks were originally made of wood, and then bamboo was used. Modern aluminum and made of composite materials appeared much later. Yes, and their shape has become curved, but this invention is mainly intended for athletes - skiers, biathletes.
It is known from what wood skis are made now - it is plastic. This material began to be used relatively recently, 40-50 years ago. Prior to this, skis were made only of wood, and the raw material was mainly birch or ash. Pine, elm, beech can also be used. The first skis were a solid board. They chose it very carefully, because it should not have any cracks, let alone knots. The tree was cut in winter, when there is no sap flow. It is easier to dry such wood so that the skis do not subsequently turn out to be prohibitively heavy.
Over time, skis began to have a multilayer structure. They were recruited from separate thin parts of different types of wood. Usually there were three. The top layer was made of hardwood, such as beech. The lower part, designed to slide, was made of birch - it is the most slippery. The interlayer consisted of rocks of medium density - aspen or pine.
It is impossible to find wooden skis for sale now, they have long been replaced by plastic ones, which, compared to wooden ones, are much lighter and glide better. But, perhaps, their most important advantage is that plastic skis are not subject to winging, i.e. deformation of skis when exposed to moisture.
