In this article, we will outline some concepts that you need to use when choosing a case fan and talk about the features characteristic of different types of fans. In addition, we will test the 120 mm akasa Amber AK-183-L2B fan, which has been serving as an active element of the Thermaltake Sonic Tower processor cooling system for more than a year, used when testing processors and video cards. And it should be noted that he has fully earned the right to become the first hero in a series of reviews dedicated to fans on our resource.
The questions we will try to answer are...
What requirements can be placed on a case fan?
- Performance level.
- Noise level.
- Appearance (presence and type of backlight).
- Additional features (support for PWM power supply, speed controller, anti-vibration mount).
What are the main differences between case fans?
1.Dimensions– impeller size.
To create internal ventilation in the case, in most cases, fans with a standard size of 80 mm, 92 mm or 120 mm are used, since mounting holes are initially provided for their installation in the case. It is clear that the larger the size of the fan impeller, the higher its ability to pump air flow. Therefore, to achieve the efficiency levels of larger models, a smaller fan will have to rotate at a higher speed and, accordingly, produce significantly more noise. Actually, for this reason, large 120 mm fans are popular.
To make these properties clearer, you can compare the characteristics of fan models of the same series from Xinruilian Science & Technology Co. having different sizes:
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Size, mm |
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Speed rpm |
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Airflow, CFM |
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Noise level, dB |
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Pressure, mm H 2 0 |
Judging by the given characteristics of the models, we can conclude that at the same rotation speed, a 92 mm fan will be 1.65 times more efficient than an 80 mm one, and a 120 mm fan will be twice as efficient as a 92 mm model, taking into account the fact that all fans have one type of impeller.
In addition to different impeller diameters, the profile size or depth of the fan is also equally important. The “classic” profile for regular cases is the 25 mm profile. Fans with a smaller profile are called low-profile, while fans with a larger profile are called high-profile. The strength of the air flow, which is characterized in the specification by the value of the maximum pressure, directly depends on the size of the profile.
For example, let's compare the characteristics of two 120 mm models - with a regular profile and a high profile, operating at the same rotation speed.
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Size, mm |
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Speed rpm |
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Airflow, CFM |
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Noise level, dB |
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Pressure, mm H20 |
The table shows that a high-profile fan is distinguished only by a better indicator of the maximum air flow pressure. In conventional computer systems there is no need to create excess pressure, so these fans are not used in them. In most cases, high-profile fans are used in servers; in addition, they have an increased rotation speed and, as a result, quite a lot of operating noise.
2. Bearing type.
Fans use three main types of bearings: plain, combined sliding and rolling, and consisting of two rolling bearings. In addition to these types of bearings, much less frequently, there are hydrodynamic types that are specially developed separately by some manufacturers.
Most often, you can determine the type of bearing by the presence of the following indices in the name of the fan model, although it is always advisable to check the official specification:
S (sleeve)
– a sliding bearing, which is essentially a bushing;
WITH (combo)
- one ball bearing and a short bushing;
B (ball) or 2B (2 ball)– two ball bearings.
The simplest and cheapest, but, unfortunately, not particularly durable is the plain bearing. This bearing looks like a small copper bushing, inside which the impeller shaft (rod) slides, rotating. A new fan with a lubricated plain bearing may be completely silent, but over time this property may be lost. In the absence of the proper level of lubrication, the bushing “wears out” quite quickly, which is why the fan begins to make noise. In addition, in the absence of lubrication, when operating in an area with elevated temperatures, the fan may completely jam. This fact is especially clearly demonstrated by cases with inexpensive Chinese power supplies, in which there were often cases of stopping the fan on the plain bearing, which ensures cooling of power semiconductor elements. As a result, the power supply failed.
The combined version of the bearing has a relatively longer bearing life.
A bearing consisting of two ball bearings is the most expensive, but at the same time, more durable option. This type of bearing can operate freely in high temperature areas. But at the same time, often among such fans you can find specimens that produce quite loud and unpleasant noise. This picture is especially typical for cheap fans, because the noise characteristics of the entire structure directly depend on the quality of manufacturing of the miniature bearing. Therefore, if you choose a product with ball bearings, do not under any circumstances go after its cheapness, because even more expensive models are rarely quiet.
3. Engine class.
All case fans are powered by four-pole DC motors. According to speed, they are all classified into three categories: low-speed up to 2000 rpm, medium from 2000 to 3000 rpm and high-speed over 3000 rpm. You can often find out the class of a fan motor by the index in its name, which is often indicated on a sticker:
L (low)
- low-speed ( up to 2000 rpm);
M (middle)
- average ( from 2000 to 3000 rpm);
H (high)
– high-speed ( over 3000 rpm).
What characterizes the data given in the manufacturers' specifications?
Fan speed measured in the number of revolutions per minute (RPM - rotations per minute). Since the fan speed itself can vary almost in direct proportion to the supply voltage, the value given in the specification corresponds to the rated supply voltage. The higher the rotation speed, the more efficient the fan is, but also usually the noisier.
Air flow can be indicated in CFM (cubic feet per minute, CFM) - cubic feet per minute or in cubic meters per hour (m 3 / h). In this case, 1 CFM ≈ 1.7 m 3 / h. This value displays the amount of “pumped” air over a certain period of time, provided there is complete absence of resistance to air flow, that is, with equal air pressure on both sides of the fan. Of course, the larger this value, the better.
Air flow static pressure fan is usually given in mm of water column and characterizes the force of air flow that the fan can create.
Recall that pressure is calculated using the formula P=F/S. That is, pressure is the ratio of the force of the air flow to the area on which it acts. The specification indicates the maximum amount of air flow that the fan creates when it cannot create air flow due to resistance.
The entire characteristics of the fan can be seen on the “Performance curve” graph.
The performance curve represents the relationship between air flow and pressure. The highest point of the curve, located on the axis, is precisely nothing more than the maximum pressure, which is given in the specification. The lowest point of the curve, lying on the other axis, corresponds to the maximum air flow of the fan when it does not have to create pressure. In real conditions, namely in a housing, the air flow must overcome some resistance. Each case individually has its own degree of resistance. The system resistance will be expressed as a slope on the graph, and the point of intersection of the straight line and the curve is nothing more than the operating point of the fan in our conditional system.
Fan life measured by the number of thousand hours during which the fan must operate and provide the declared characteristics. The author of the article does not fully know under what operating conditions the given values are achieved, since the service life directly depends on the operating conditions. It is assumed that the fan is capable of operating for the specified number of hours without losing its noise qualities. The resource largely depends on the type and quality of the bearing. For plain bearings, 30,000 hours are usually specified, for combined bearings - 45,000 hours, and for double ball bearings, values of 60,000 hours and above are given.
In most cases, a fan on a sliding bearing can operate quite quietly for about a year, although manufacturers claim a figure of 30 thousand. Therefore, one should not be biased about these numbers - they are quite relative. And if you dig deeper, it turns out that the manufacturer also implied periodic maintenance of the fans, i.e. a lubricant that ordinary users rarely produce.
Now let's go back to the hero of our review, the fan. akasa AK-183-L2B and look at its specification:
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akasaAK-183-L2B |
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Size, mm |
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Rotation speed, rpm |
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Airflow, CFM |
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Pressure, mm H20 |
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Resource, h |
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Bearing type |
two swings |
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3 pin |
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Noise level, dB |
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Supply voltage, V |
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Products webpage |
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average price |
The akasa AK-183-L2B fan is packaged in transparent plastic packaging. The back of the package contains a blue cardboard sheet, highlighting the transparent body and translucent amber-yellow fan impeller. In general, everything is decorated in the familiar blue and yellow corporate colors of the Akasa Group.
On the back of the cardboard insert there is a specification in five different languages.
In addition to the fan, at the very bottom of the package there is a small black cardboard box with an inscription translated as “3-4 pin adapter”.
Therefore, it is not at all surprising that the box contained an adapter that allows you to connect the fan from the connectors of peripheral devices, and in addition, it additionally has a 3-pin connector for controlling the fan rotation speed. Also in the small black box were four screws for installing the fan into the case.
The akasa AK-183-L2B fan body is made of white transparent plastic, and its impeller is made of amber yellow translucent plastic. Actually, if we consider the entire product range of the akasa company, we rarely come across any simple and standard solutions, because the company distributes products, for the most part, designed specifically for modding. But this does not mean at all that if you do not consider yourself to be a modder and are accustomed to evaluating a product only for practical reasons, then this fan and other similar products are not suitable for you. In fact, when producing products for so-called difficult users, modders or overlockers, increased attention is always meant, first of all, to the quality of workmanship and its somewhat higher properties. Therefore, it is not at all surprising that almost always the consumer qualities of such products are higher than those of simple goods.
Externally, the fan, of course, stands out primarily with its beautiful combination of yellow and white colors, and it seems that such a fan simply must have a backlight, but in fact it does not. From an aerodynamic point of view, no innovations or know-how have been implemented in the fan - a simple seven-blade impeller.
The akasa AK-183-L2B fan is a low-speed model, its nominal rotation speed is 1400 rpm, while the maximum air flow can reach 44.8 CFM, and the static pressure is 1.1 mm water column. The characteristics are neither super high nor quite ordinary, but this is not surprising, since for a case fan of a home system, first of all, increased noise requirements are placed.
And in this regard, the specification indicates a fairly low noise level of 18 dB. It should be noted that the akasa AK-183-L2B fan is based on two ball bearings, and its service life, according to the manufacturer, is 80,000 hours. The usual value for ball bearings is 60,000 hours, so a slightly increased value gives reason to hope for a better approach to their manufacture, because we have already noted that it is the quality of the ball bearing that determines its noise characteristics.
The fan is powered by a 3-pin power connector, which does not support pulse-width power supplies.
Testing
The practical part of the test consists of two stages of testing the generated air flow of the fan at nominal speeds, as well as assessing its volume by ear.
Test No. 1
In the first test, the fan will act as an active element of the Thermalright SI-128 cooler. Testing is carried out in an open case, and the main controlled parameter is the heating temperature of the Intel Core 2 Duo E6300 processor overclocked to 2.8 GHz and the temperature of the motherboard.
Test No. 2
In the second test, the fan will be used for its intended purpose as a case fan installed on the rear panel and operating as an exhaust fan. During the test, the case will be closed and there will be no other fans turned on. The main controlled parameter will also be the heating temperature of the Intel Core 2 Duo E6300 processor, but now without overclocking, which is equipped with a passive cooling system Thermaltake Sonic Tower (CL-P0071) and the temperature of the motherboard. The test result is recorded after a 10-minute “run” of the processor stress test in the Everest application.
The test platform configuration with an Intel processor consists of the following components:
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Motherboard |
Gigabyte GA-965P-DS4 (Intel P965 Express) |
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CPU |
Intel Core 2 Duo E6300 (LGA775, 1.86 GHz, L2 2 MB) @2.8 GHz |
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RAM |
2 x DDR2-800 1024 MB Apacer PC6400 |
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Video card |
EVGA GeForce 8600GTS 256 MB DDR3 PCI-E |
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HDD |
Samsung HD080HJ, 80 GB, SATA-300 |
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Optical drive |
ASUS DRW-1814BLT SATA |
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power unit |
Chieftec CFT-500-A12S 500W, 120 mm fan |
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CODEGEN M603 MidiTower |
The akasa AK-183-L2B fan demonstrates good performance on par with other competitors. We can confirm the fairly low declared noise level of 18 dB only with our subjective opinion. The indicated value is indeed quite consistent with the real noise level - at maximum speed it emits a slight hum.
Conclusions.
The akasa AK-183-L2B fan is not exclusively a beautiful decoration for modding, as it might immediately seem to the buyer. It can create a fairly large air flow, and, most importantly, it produces a fairly low noise level. If we take into account its reasonable price for a high-quality model of a ball-bearing fan, then in this category of goods it will be one of the best in terms of price/consumer quality ratio. Let us repeat that in our test laboratory the akasa AK-183-L2B fan has been in operation for more than a year, and its noise qualities have remained virtually unchanged during this time.
Advantages:
- creates a large air flow;
- low noise level;
- good price/performance ratio.
The disadvantages include:
- lack of PWM support.
We express our gratitude to the company PF Service LLC (Dnepropetrovsk) for the equipment provided for testing.
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Mod F1 1983 y 1984 para RFactor:
Estimados compañeros de la pasión del automovilismo virtual:
Inspirado en los gráficas de los maravillosos mods 1982, 1983 y 1984 de Pedro & Ripping Corpse para GP4 y las físicas del espectacular supermod 1978-2008 de Birkuc para F1C, Labombarda tiene el agrado de anunciarles la próxima salida del Mod F1 temporadas 1 983 and 1984 para rFactor.
Adelantándonos a los posibles cambios de reglas en la F1 para 2012 con el regreso de los motores turbo y el efecto suelo, les traigo estas espectaculares temporadas.
Por primera vez, un solo mod albergará dos temporadas juntas completas.
Además contará con todos los coches de las mismas temporadas en sus diferentes versiones y con sus distintas variedades de pintado para los eventos históricos.
El mod contará con la posibilidad de escoger por defecto la configuración para correr en ligas (LE) y a través de las mejoras acceder a la versión histórica (HE) de los diferentes veriantes de un modelo y hasta los distintos modelos usados en la temporada.
English:
RFactor Mod F1 Season 1983 and 1984:
Dear friends of virtual motor racing passion:
Inspired in graphics of wonderful GP4 mods 1982, 1983 and 1984 by Peter & Ripping Corpse and the physics of the spectacular Birkuc supermod 1978-2008 for F1C, Labombarda is pleased to announce the upcoming release of F1 Mod seasons 1983 and 1984 for rFactor.
In advance of the possible rule changes in F1 in 2012 with the return of turbo engines and the ground effect, I bring these spectacular seasons for you.
For the first time, a single mod will have two full seasons together.
Also enjoy all the cars of the same seasons in different versions and different varieties of painting to historical events (skins).
The mod will feature a choice of default settings to run leagues (League Edition) and through improved access to the historical version (HE) of the various veriantes of a model and to the various models used in the season.
Coming soon!. Stay tuned!
French:
1983 et 1983 Mod F1 pour rFactor:
Chers compatriotes moteur de course virtuelle passion:
Inspiration par les mods graphiques merveilleux 1982, 1983 et 1984 Peter & Ripping Corpse à GP4 et spectaculaire supermod physique de Birkuc pour F1C 1978-2008, Labombarda est heureuse d"annoncer la sortie prochaine de F1 Mod saisons 1983 et 1984 pour rFactor.
En prévision des changesments de règles possible en F1 en 2012 avec le retour des moteurs turbo et l"effet de sol, je vous apporte ces saisons spectaculaires.
Pour la première fois, un mod unique maison de deux saisons complètes ensemble.
Profitez également de toutes les voitures de la même saison dans différentes versions et différentes variétés de la peinture à des événements historiques.
Le mod proposera un choix de paramètres par défaut pour exécuter lieues (LE) et par un meilleur accès à la version historique (SE) de la veriantes différentes d"un modèle et les différents modèles utilisés dans la saison.
Pronto. Restez à l"écoute!
Portuguese:
Mod F1 1983 e 1984 pra rFactor:
Caros colegas de paixã na corridas virtuais:
Inspirado pelas graficas dos maravilhosos mods 1982, 1983 e 1984, da Peter & Ripping Corpse pra GP4 e pelas físicas da espetacular supermod de Birkuc pra F1C 1978-2008, Labombarda tem o prazer de anunciar o próximo lançamento do Mod F1 das e Stações 1983 and 1984 para o rFactor.
Em antecipação a possíveis mudanças de regras na Fórmula 1 em 2012 com a volta dos motores turbo e do efeito solo, trago essas temporadas espetaculares pra voçés.
Pela primeira vez, um mod single vai abrigar duas temporadas juntas.
Também pode desfrutar de todos os carros das estações do ano mesmo em diferentes versões e diferentes variedades de pintura para os acontecimentos históricos.
O mod contará com uma escolha de configurações padrão para correr léguas (LE) e através de um melhor acesso à versão histórica (HE) da veriantes diferentes de um modelo e para os diferentes modelos usados na época.
Pronto. Fique ligado!...
Algunas images:
1983:
http://img696.imageshack.us/img696/2485/grab112i.jpg
http://img155.imageshack.us/img155/8558/grab105.jpg
http://img135.imageshack.us/img135/2571/grab106.jpg
http://img683.imageshack.us/img683/3360/grab108.jpg
http://img268.imageshack.us/img268/9837/grab109j.jpg
http://img846.imageshack.us/img846/5549/grab111.jpg
1984:
http://img15.imageshack.us/img15/7954/grab081v.jpg
http://img847.imageshack.us/img847/299/grab080.jpg
http://img690.imageshack.us/img690/1622/grab094x.jpg
http://img833.imageshack.us/img833/358/grab095.jpg
http://img822.imageshack.us/img822/189/grab096j.jpg
http://img862.imageshack.us/img862/9211/grab097.jpg
http://img683.imageshack.us/img683/6969/grab098r.jpg
http://img844.imageshack.us/img844/2229/grab099.jpg
http://img576.imageshack.us/img576/1895/grab100.jpg
http://img801.imageshack.us/img801/3871/grab102.jpg
http://img263.imageshack.us/img263/9191/grab104.jpg
Mod F1 1983 & 1984 para RFactor:
1 Mod
2 Temporadas / Seasons / Saisons (1983 – 1984)
3 Tire Brands / Marcas de Neumáticos / Marque de pneu / Marca do pneu
4 Continents
7 Engines/Motors/Moteurs
Alfa Romeo 1260V12 890T v8
BMW 12/13 L4t
Ferrari 021 V6t 031 V6 t
Ford Cosworth DFV-V8 DFY-V8
Hart 415T L4t
Honda RA163E V6 t
Renault EF1 V6t EF4 V6t
TAG Porsche P01 V6t
15 Countries/Paises
16 Teams/Equipos/Equipes:
Alfa Romeo 183T 184T
Arrows A6 A7
ATS D6 D7
Brabham BT52 BT52B
Ferrari 126C2B 126C3 126C4
Ligier JS21 JS23
Lotus 91 92 93T 94T 95T
McLaren MP4/1C MP4/1E MP4/2
Osella FA1D FA1E FA1F
RAM March 01
RAM 01 02
Reanault RE30C RE40 RE50
Spirit 201 201C 101
Theodore N183
Toleman TG183B TG184
Tyrrell 011 012
Williams FW08C FW09 FW09B
All drivers, all versions of the cars. / Todos los pilotos, todas las versiones de los coches. / Tous les pilotes, toutes les versions des voitures. / Todos os drivers, todas as versões dos carros
Algunas instrucciones:
1 – Los coches tiene limitador en boxes: Si bien en esa época, los coches F1 no tenían limitador, aquí decidí ponerlos ya que el track-pack tiene como límite en boxes 300 km/h con lo cual de hecho en la práctica no habría limitador. La utilidad del botón del limitador es que éste enciende la luz intermitente de boxes. Sin limitador la luz no funcionaba. Por ello opté en poner el limitador.
2 – Los autos tienen un filtro para cada trazado real del trackpack, discriminado si clasificaron o no. De este modo cada vehiculo/piloto tendrá en sus filtros (clases) la carrera en la que participó (se inscribió al menos) y si clasificó o no. Si se desea correr una pista tal cual históricamente ocurrió tendremos variabilidad en la cantidad de pilotos que se presentaron a cada carrera (AI). Para correr con todos los pilotos, habrá que ir agregando AI hasta que empiecen a repetirse. Una alternativa será poner en el Track-pack de cada pista la cantidad de AI real de cada evento.
3 – Para efectuar campeonatos individuales con el trackpack de VirtualClassics deberán elegir un coche que pueda correr todo el campeonato. Para ello verificar que el el archivo .rfm, debajo de Season =, las opciones de “Vehicle Filter =” coincidan con las diferentes clases del archivo veh del coche elegido.
4 – Para salir de boxes un poco más rápido conviene salir con las revoluciones del motor altas y de una manera inconstante para evitar trompos.
5 – Por defecto las gomas tiene poco aire. Facilitan la conducción inicial, pero los mejores tiempos saldrán una vez infladas con mayor presión.
6 – La asignación del turbo esta seleccionada por defecto en su menor potencia (4 ó 5) para preservar la vida útil del motor. Subir esta asignación, dará mayor potencia pero bajará la vida útil del motor y calentará con mucha mayor facilidad. Si bien esto podría solucionarse aumentando el tamaño de los radiadores, en contraprestación tendrán menos eficiencia aerodinámica.
7 – Thanks to "Labombarda Consulting Management" for sponsoring this mod / Gracias a "Labombarda Consulting Management" por patrocinar este mod / Merci à "Labombarda Consulting Management" pour le parrainage de ce mod / Graças à "Labombarda Consulting Management" para patrocinar este mod / Grazie al "Management Consulting Labombarda" per sponsorizzare questo mod
Enlaces:
Presentacion (Moviefiles)
http://www.megaupload.com/?d=10SOYTUT
http://depositfiles.com/files/nsjljd9hy
Comentarios en español (voces Mercado y Benedetto)
http://www.megaupload.com/?d=SZUTQNB3
http://depositfiles.com/files/txd41xqmj
Mod. F1 1983 & 1984, parte principal
http://www.megaupload.com/?d=44BZ18KV
VERSION 1.2:
New textures for tires & correct bug suspension in Ligier84 hdv. Hiss brakes sound was adjusted. Engines on upgrades were corrected.
Changes on the downforce levels affecting front and rear wing (new increment value and default settings) body and diffuser to make the car more nervous.
Changed weight of cars (adding 80 kg for driver&stuffs weight to cars). Changed inertia levels as consciousness of a major weight.
Changed CGHeight making it taller and different between cars. +0.03 aprox
Changed AIPerfUsage to let ai drivers better cornering. AIPerfUsage=(0.990, 0.950, 0.960) //(0.990, 0.960, 0.930)
Changed LeftCasterRange & RightCasterRange to feel better steering (realfeel support). (16 to 40)
Revised engines.ini files (New reving map and IdleRPMLogic=(2000, 3000) to enhace the starting).
Fixed Laffite for Lafitte.
Adding the League Edition fully functional.
Changes in to solve the problem of overlapping of some cars in the spinner.
VERSION 1.2:
Nuevas texturas para los neumáticos y corrección del fallo en la suspensión del HDV del Ligier84. El sonido del silbido de los frenos se atenuó. Se corrigió la selección de los motores en los upgrades.
Cambios en los niveles de carga aerodinámica afectando los alerones delantero y trasero (nuevo valor de incremento y la configuración por defecto), el cuerpo del coche y el difusor para hacerlo más nervioso.
Cambió el peso de los coches (la adición de 80 kg para el conductor y su equipamiento en el de peso a los coches). Cambiaron los niveles de la inercia como consecuencia de un peso mayor.
Cambiado CGHeight por hacerlo es más alto y diferente entre los coches. 0.03 aprox
Cambiado AIPerfUsage para que los conductores de IA mejoren en las curvas. AIPerfUsage = (0.990, 0.950, 0.960) / / (0.990, 0.960, 0.930)
Cambiado LeftCasterRange y RightCasterRange para mejorar la sensación de la dirección (apoyo para RealFeel). (16 a 40)
Revisados ??los archivos engines.ini (Nuevo mapa revolucionado y IdleRPMLogic = (2000, 3000) para potenciar el arranque del coche).
Corrección a Laffite para Lafitte
Adición de la Edición Liga Totalmente funcional.
Se cambió los para resolver el problema de la superposición de algunos coches en la presentación (spinner).
Latest Formula 1 1983-1984 Comments
Python is loaded with tons of useful modules (urllib2 and serial, for example) ready to use, and their documentation is very, very good.
Please enable Javascript to use the unit converter
›› More information from the unit converter
How many cfm in 1 cubic meter/minute? The answer is 35.314666212661.
We assume you are converting between cubic feet/minute and cubic meter/minute.
You can view more details on each measurement unit:
cfm or cubic meter/minute
The SI derived unit for volume flow rate is the cubic meter/second.
1 cubic meter/second is equal to 2118.8799727597 cfm, or 60 cubic meter/minute.
Note that rounding errors may occur, so always check the results.
Use this page to learn how to convert between cubic feet/minute and cubic meters/minute.
Type in your own numbers in the form to convert the units!
›› Quick conversion chart of cfm to cubic meter/minute
1 cfm to cubic meter/minute = 0.02832 cubic meter/minute
10 cfm to cubic meter/minute = 0.28317 cubic meter/minute
20 cfm to cubic meter/minute = 0.56634 cubic meter/minute
30 cfm to cubic meter/minute = 0.84951 cubic meter/minute
40 cfm to cubic meter/minute = 1.13267 cubic meter/minute
50 cfm to cubic meter/minute = 1.41584 cubic meter/minute
100 cfm to cubic meter/minute = 2.83168 cubic meter/minute
200 cfm to cubic meter/minute = 5.66337 cubic meter/minute
›› Want other units?
›› Definition: Cubic foot/minute
Cubic feet per minute (CFM) is a measure used in Industrial hygiene and ventilation engineering. It describes the rate of flow of a gas or air volume into or out of a space.
A standard measurement of airflow that indicates how many cubic feet of air pass by a stationary point in one minute. The higher the number, the more air is being forced through the system. The volumetric flow rate of a liquid or gas in cubic feet per minute. 1 CFM equals approximately 0.47 liter per second.
›› Metric conversions and more
website provides an online conversion calculator for all types of measurement units. You can find metric conversion tables for SI units, as well as English units, currency, and other data. Type in unit symbols, abbreviations, or full names for units of length, area, mass, pressure, and other types. Examples include mm, inch, 100 kg, US fluid ounce, 6"3", 10 stone 4, cubic cm, meters squared, grams, moles, feet per second, and many more!
Ultralight travel gear is becoming increasingly sophisticated. This trend is most evident in the ever-evolving category of individual shelters, better known as bivy bags(“biwi”)
If you are not yet familiar with the variety of bivouac options that exist, now is the time to fix that. You'll be amazed at the variety of choices and thoughtful designs available to the independent traveler looking to reduce the weight of his gear.
Who uses bivouac bags? People who:
- Often travel alone;
- They make big wall climbs that require more than one day to complete;
- They often go on long hikes on bicycles;
- Every gram of load carried is counted;
- I don't mind sleeping in tight spaces.
Basics
Bivvy bags were invented to meet the needs of climbers who needed protection for their sleeping bags from the elements during ascents that took several days, especially on big walls.
Early bivouac bags were simply a waterproof nylon cover for sleeping bags - good at protecting the sleeping bag from rain and with mediocre ventilation capabilities.
Today, the design of bivouac bags includes two layers of fabric. The bottom tier is usually made of a durable nylon derivative (usually taffeta, sometimes oxford) that is coated with urethane to make it waterproof. The same material is used by most manufacturers in the production of tent floors.
The top tier is typically made from ripstop nylon (a lighter fabric) and finished with a waterproof/breathable laminate such as Gore-Tex®, Tegraltex or REI Elements®.
Over time, the original bivouac spawned a related product with tent-like characteristics - the bivy shelter ( bivy shelter). While slightly heavier, this type of shelter has two features that traditional bivys lack - an expanded area of protected free space and complete protection from bad weather conditions and insects. Thanks to these features, the popularity of this type of shelter is growing among consumers who are keen on hiking, especially among those traveling light.
Additionally, there is a bivy-like category of double-layer tents. The average weight of these tents (about 1.8 kg) is higher than the weight of a standard bivy (900 g or less), but they offer more interior space along with a modest mass - a comforting argument for soloists who need the ability to assume a sitting position in their shelter. but the ability to travel light is also important. Examples: REI Sololite; Kelty Clark; Walrus Micro Swift; Sierra Designs Clip Flashlight.
Bivvy bags
Even when designed with modern fabrics, the traditional bivouac bag is intended primarily for mountain climbers or ideological minimalists - people who drill holes in their spoons to save a few extra grams.
A regular bivouac bag performs two basic functions: protects the sleeping bag from moisture and increases its temperature by about 5 °C.
Biwi Has an open head area. When it rains, some moisture may get inside through the unprotected head hole. To minimize the penetration of moisture inside, you should tighten the lace located around this hole. Of course, this will turn the head hole into a nose hole, which will be unacceptable for some people. But this is a small compromise for the ultra-light backpacker who appreciates bivouac bags for their minimal weight.
Other Considerations
Some models allow you to create openings on the side of the bivy bag, allowing you to sort your gear or cook food while staying warm and protected from the elements.
A full-length bivy zipper will be helpful in providing more options for ventilation.
Pay attention to the factory sealed seams; leading brands usually offer this useful feature.
Some models come with straps that help keep your mat in place.
In warm conditions, sometimes people do not use a sleeping bag at all, but simply sleep directly in the bivy bag.
Typical representatives of bivouac bags: Moonstone Personal Shelter; Standard Bivy from Outdoor Research; REI Cyclops.
Bivi type shelters
The evolution of the bivy bag produced a new category of low-rise tent known as bivy shelters. These models have mesh inserts located in the area of the head opening, as well as small suspension systems (pegs, arcs) that hold the fabric above the tourist’s face. In a bivy-type shelter, complete isolation from insects and rain can be achieved. This may require some ingenuity to provide ventilation during a rainstorm, but it is quite possible to achieve.
For many tourists traveling long and light, a bivi-type shelter with its additional wedge-shaped reinforcement in the head area can provide a sufficient level of comfort. In areas with constant rain, bivy-type shelters lose their attractiveness; It will be difficult to wait out the storm in a shelter in which you cannot take a sitting position. However, using bivy shelters makes sense with favorable weather conditions such as the Sierra Nevada. Examples: Integral Designs Unishelter; Advanced Bivy Sack from Outdoor Research.
Other Considerations
Is the bivy too narrow for you? Initially you might think so. But don’t immediately dismiss this cover option. Of course, a tent offers tourists a spacious, safe shelter with a roof over their heads. However, bivi allows you to “merge” more strongly with nature. It's almost like sleeping under the stars. At the same time, you have sufficient protection from rain and insects, which is also lightweight. However, if being in tight spaces makes you anxious, you will likely not feel comfortable wearing a bivy, especially in bad weather. In this case, consider purchasing a tent.
How does air circulate inside the bivy? A breathable/waterproof laminate such as Gore-Tex allows moisture to evaporate through the fabric. At the same time, preventing raindrops from seeping through the fabric. Breathable/waterproof bivouac bags perform best in situations where a hiker's warm, sweaty body rests in cold, dry conditions. In rainy conditions, although modern bivys are designed with plenty of overlap and zippers, you are unlikely to have to zip them all the way up. Manual ventilation helps maintain an acceptable level of humidity inside the bivouac bag.
Is it possible for condensation to form inside the bivy? Potentially, yes. Essentially, a bivy is a single-layer tent. The warm vapor coming from your body and lungs rises and collides with colder air. When steam comes into contact with the laminate of the bivvy bag, the air can no longer transport all the moisture, thus some of it collects on the inside of the fabric in question. In a two-layer tent, this moisture passes through the breathable inner tent and settles on the outer one. In the case of a bivy, this may cause a small amount of moisture to accumulate on the inside of the bivy. In cold conditions, this can cause an ice crust to form on the inside.
Will a sleeping bag actually stay dry in a bivouac? In rainy (humid) weather conditions, Gore-Tex fabric can sometimes produce a cold and wet feeling when in contact with the skin, but this is only a feeling and not a wet feeling. Good ventilation helps minimize this sensation.
Brief summary
Bivvy bags: A good choice for mountaineers and minimalist hikers who go on short (one- and two-day) hikes. Requires a mindset that adapts well to Spartan conditions.
Bivi Shelters: Popular among ultralight riders, long-distance travelers and cyclists. A good choice for tourists traveling in areas with little rainfall. The extra space and full protection make them a viable option for tourists who can psychologically adapt to spending the night in a confined space. Narrow but light.
Compact tents: Some models in the 2kg range offer a combination of space and modest weight; in many cases will be the preferred choice for the average tourist.
See boast... Dictionary of Russian synonyms and similar expressions. under. ed. N. Abramova, M.: Russian Dictionaries, 1999. boast boast, brag Dictionary of Russian synonyms ... Synonym dictionary
BRAGGING, I boast, I boast; imperfect (colloquial). Boast, brag. P. new things. Ozhegov's explanatory dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 … Ozhegov's Explanatory Dictionary
Nesov. decomposition 1. Speak about yourself or someone else with praise; boast. 2. Boastfully promise to do something. Ephraim's explanatory dictionary. T. F. Efremova. 2000... Modern explanatory dictionary of the Russian language by Efremova
Boasting, boasting, boasting, boasting, boasting, boasting, boasting, boasting, boasting, boasting, boasting, boasting, boasting, boasting, boasting, boasting, boasting, boasting,... ... Forms of words
boast- to boast, to boast, to boast... Russian spelling dictionary
boast- (I), praising, praising, praising, praising... Spelling dictionary of the Russian language
See Boast... encyclopedic Dictionary
boast- see boast; I/am, I/am; nsv.; decomposition Boast to each other. Boast about your strength... Dictionary of many expressions
boast- on/praise/i/t/sya… Morphemic-spelling dictionary
Breed (relatives) to boast, to boast of one’s noble origins Wed. Our breed served under the kings. Wed. And we live with her, we just quarrel and boast about our relatives. Koltsov. To each his own talent. See, a Russian person cannot live without relatives. See the snout... ... Michelson's Large Explanatory and Phraseological Dictionary
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