Archive for the ‘helicopter’ tag
Rotor Blades
What are the postives and negatives of a helicopter having 2 rotor blades verses 4 verses 6?
Just would like to the positives and negatives of a helicopter having less rotor blades vs more.
Rotor blades have to carry the weight of the whole helicopter, one way or another.
This is achieved by having the rotor spin, producing lift, with the lift from any section of the rotor being the combination of the local angle of attack, airspeed and surface area.
Unlike the wing of an aircraft, a rotor will have extreme speed variation, going from essentially zero at the hub (when the helicopter is hovering) to a maximum at the tip. This gets more complicated when the helicopter moves horizontally as now the forward motion has to be added to the rotational velocity, with one side having a speed that is the sum of the rotation and the translation speed, while the other sides sees the difference between those speeds. The angle of attack is changed cyclically to compensate for the lift difference, but there is of course a limit to how much angle of attack a blade can have before it stalls.
Speed, angle of attack; we are left with the area.
One can get the required area by having two wide chords blades, by having two very long blades, or by having more than two blades.
Wide chords are less efficient than narrow ones as they would have a lower aspect ratio. And of course, a wide chord at the hub would not give any advantage since that part is hardly moving at all. The result is that a properly designed Rotor Blade would have some sort of optimal aspect ratio, in other words, a chord that is in proportion to its length.
So, we can now decide two large (long and wide) blades, or several smaller (but with about the same length to chord ratio) one with the same area.
And this is when compressibility effect shows itself. The tip of a blade would be moving at a very high speed, at some point, the tip of a blade of a fast moving helicopter would reach close to the speed of sound. That will create some shock wave on the rotor blade, that will be coming and going at each rotation (since the retreating blade would see the difference between rotation and translation speed, there would not a be a shock at that point). This will make the helicopter quite noisy, and since noise is energy taken away, less efficient.
So, one the one hand, you have a simpler system — two blades, which means less parts, and a simpler cyclic system, since there are only two blades to cyclically pitch up and down — or a more complex, heavier and costlier one that will be quieter but will permit a higher cruise speed and be more fuel efficient.
It will always be a compromise that has to be decided as a function of the typical mission.
Helicoper synced rotor blades with video camera
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4 Replacement Gaskets compatible with Original Magic Bullet $0.01 This quality rubber gaskets are great replacements if your gaskets break on your blades for the Magic Bullet… |
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KitchenAid RVSA Slicer/Shredder Attachment for Stand Mixers $47.95 This attachment performs the cutting and shredding duties your food processor might: select the proper cone, slip it into the plastic housing, and attach all to your stand mixer’s hub with a metal shaft. You can shred potatoes, onions, nuts, and chocolate, or slice vegetables for cooking or munching. While it adds versatility to your mixer, the unit is cumbersome to disassemble–more so than Kitch… |
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Deluxe Starfrit Electric Rotato Potato Peeler Express $22.69 The indispensable kitchen tool! Peels potatoes, fruits and vegetables instantly, at the push of a button! The Deluxe Rotato Express is the amazing peeling machine that peels away potato, vegetables and fruit skins in seconds in one fast, easy motion! Best of all, the Deluxe Rotato Express peels just the skin, without wasting any of the nutritious part of the fruit or vegetable. To use the Deluxe… |
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RC HELICOPTER SETUP & BALANCE $29.95 Ready to learn about all the details of setting up and balancing the mechanical and electronic components of your helicopter system? This is the program you need! For ALL electric and nitro collective pitch helicopters.Whether you are new to helicopters or an intermediate pilot ready to get into advanced aerobatics, this program is packed with tips, hints, tricks, and techniques for customizing … |
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Emjoi RotoShave AP-3RS Rechargeable Electric Razor $29.99 Your face will experience the best of both worlds with the Emjoi Rotoshave Electric Razor. Combining the convenience of an electric shaver with the closeness and efficiency of a razor blade, this versatile shaver will give your face the close and comfortable shave it deserves day after day. At the heart .caption { font-family: Verdana, Helvetica neue, Arial, serif; font-size: 10px; font-weight:… |
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huey x (PC) (UK) $27.99 The Bell UH-1 is without a doubt one of the best-known helicopters to most people. It was imprinted in our culture by the moving images from the Vietnam War were it changed the face of warfare. And it never left as thousands are still flying in every corner of the world. Fifty years after it first flew it is still in production and that’s something no other helicopter can claim. The characteristic… |
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FlyingClub X Expansion for MS Flight Simulator X/2004 DVD $24.99 Just Flight’s new Flying Club X expansion is fully updated for Flight Simulator X, with new content and features. Five of the most popular light aircraft in the world – join the club & fly them all over the world! Flying Club X features the PA28-161 Warrior, PA38-112 Tomahawk, C152, the twin-engined PA34-200T Seneca II and the Schweizer S300CBi helicopter. All the aircraft have authentic and reali… |
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Noctua (NF-B9 PWM) – 92mm Two Speed Premium Fan, 1600/1300 RPM, SSO2 Bearing with NE-FD1 PWM IC $18.79 Connector 4-pin PWM Bearing SSO Blade Geometry NF-B9 Blade Design Rotational Speed (+/- 10%) 1600 RPM Rotational Speed with L.N.A. (+/- 10%) 1300 RPM Min. Rotational Speed (PWM) 300 RPM Airflow 64.3 m³/h Airflow with L.N.A. 52,6 m³/h Acoustical Noise 17,6 dB(A) Acoustical Noise with L.N.A. 13,1 dB(A) Static Pressu… |
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Panaflo NMB 92×92x25mm High Speed Fan, Model FBA09A12H1BX with 3pin connector $6.00 Highest quality Panaflo fans. These premium fans are known as high performance and low noise work horse fans. All Panaflo/NMB fans include 3 Pin connector with 11inch lead for easy direct connect to motherboard or fan controller. Features: * 3 PIN leads with RPM Sensor * Operating Temperature: -10°C +70°C (65% RH) * Storage Temperature: -40°C +75°C (65% RH) * Bearing Type: Hydro Wave * Conn… |
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Panaflo Low speed 92mm 3 pin fan FBA09A12L $2.99 Highest quality Panaflo fans. These premium fans are known as high performance and low noise work horse fans. All Panaflo fans include 3 Pin connector with 11inch lead for easy direct connect to Motherboard. Available in LOW and MEDIUM. Click here for High Speed with active Sensor. Features: * 3 PIN leads (not sensor active) * Operating Temperature: -10°C +70°C (65% RH) * Storage Temperature: -4… |
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RF Single Blade 15-inch 3.5-channel RC Helicopter $63.99 RF Single Blade 15-inch 3.5-channel RC HelicopterMedium size 3.5 channel single top rotor helicopterLooks like and flies like real helicopters |
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TrueCut Rotary Blade Sharpener $24.68 Materials: PlasticPackage includes one (1) TrueCut Rotary Blade Sharpener and instructionsSharpener can be used on flat surface |
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Orbital Rotary Blade Sharpener $23.52 Sharp blades making cutting easier and faster Now you can get a straight, razor sharp edge on your rotary cutter in seconds Ideal for quilting, crafts, upholstery, paper cutting and more |
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Colonial Rotary Blade Sharpener $12.94 Complete your sewing supplies with this rotary blade sharpener by ColonialSewing accessory features dual rotary blade sharpeners to restore your cutter’s razor-like edge Sewing tool for use with all brands of rotary blades |
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OLFA Rotary Cutter 45 mm Blades (Pack of 10) $37.99 Add to your sewing and crafts experience with this 10-pack of 45 mm bladesRotary blades made of high-quality stainless steelRefill blades will allow you continued use of your rotary cutter |
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OLFA Rotary Cutter 60 mm Blades (Pack of 5) $23.7 Add to your sewing and crafts experience with this 5-pack of 60 mm bladesRotary blades made of high-quality stainless steelRefill blades will allow you continued use of your rotary cutter |
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Fiskars 65-mm Rotary Cutter Refill Blades $6.93 Fiskars rotary standard blade is a long-lasting, razor-sharp bladeSewing and quilting is easier when you have a fresh, sharp blade Craft refill blades can be used for fabric, paper and more |
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Rotary Blade 28-mm Refill (Pack of 10) $20.99 Get a closer shave with new replacement blades for your rotary shaverReplacement blades fit RTY1 and RTY1/DX shaversRefill blades are 28 millimeters |
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OLFA Rotary Cutter 45mm Blades (Pack of 5) $26.49 Add to your sewing and crafts experience with this 5-pack of 45 mm Olfa bladesRotary blades made of high-quality stainless steelRefill blades will allow you continued use of your rotary cutter |
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Colonial Rotary Blade Sharpener $13.64 Complete your sewing supplies with this rotary blade sharpener by ColonialSewing accessory features dual rotary blade sharpeners to restore your cutter’s razor-like edge Sewing tool for use with all brands of rotary blades |
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Clover 45-mm Rotary Blade Refill $6.24 Materials: Steel, polypropylenePackage includes one (1) blade and one (1) blade holderSteel blade |
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Colonial 28-mm Rotary Blade Sharpener $12.99 Complete your sewing supplies with this rotary blade sharpener by Colonial. This sewing accessory features dual rotary blade sharpeners to restore your cutter’s razor-like edge. |
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Ergo 2000 Rotary Cutter Replacement Blades $17.99 Manufactured to fit the Ergo 2000 Rotary CutterReplacement blades fit most 45 mm rotary cuttersPackage includes five blades |
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Rotary Trimmer Titanium 28mm Straight Replacement Blade $8.49 These F style blades work perfectly with Fiskars 28mm rotary trimmers. The titanium coated blade is 3X harder than stainless steel for superior durability. |
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OLFA 18 mm Small Rotary Cutter $7.29 Complete your sewing kit with this OLFA 18 mm rotary cutterSewing accessory boasts easy blade change for safetyCutter is ideal for intricate crafts and sewing projects |
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Buffalo Tools 2-in-1 Cufoff/Die Grinder Kit $18.99 This 2-in-1 die grinder kit from Buffalo Tools includes a plethora of useful tools. This kit includes rotor blades, valve plug, o-rings and many more useful tools. |
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Stick 45 mm Rotary Cutter $11.96 Rotary cutter is easy to hold and useSewing accessory’s blade is easy to changeFabric cutter features a sharp and long-lasting blade with a locking blade guard |
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Fiskars 60-mm Stick Rotary Cutter $17.38 Fiskars rotary cutter with an easy to hold, easy to use and easy to change bladeSharp, long-lasting blade with blade guardCan be used right- or left-handed without changing blade assembly |
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Remington SPRCDN Replacement Head for all Pivot and Flex Rotary Shavers $23.73 Restore your shaver to peak performance with this 360-degree Pivot and Flex replacement head for all Remington pivot and flex rotaries. This replacement has full floating heads, dual-track cutters and titanium-coated blades. |
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Dahle Personal Rotary Pencil Sharpener $22.49 This Dahle personal rotary pencil sharpener features an automatic cutting system, with precision cutting blades made of Solingen steel. This sharpener has a twistable dial that sets the desired degree of pencil sharpness. |
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Cardmaker Pinking Click Blades (Pack of 3) $11.39 Paper cutters make a great addition to your craft collectionClick Blades fit Purple Cows Rotary Trimmer models 1030, 1040, 1040c and 1050Each scrapbooking tool package includes three blades |
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Fiskars Portable Rotary Trimmer $39.49 This Fiskars portable rotary trimmer features a 28 millimeter rotary blade which can cut up to 10 layers of paper. This trimmer has a scale and grid permanently printed underneath for measuring. |
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Wahl Kennel Pro 14-piece Pet Grooming Kit $96.99 This 14-piece pet grooming kit by Wahl includes a direct drive rotary motor clipper, blade guard, scissors and 4 color guide combs. |
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Fiskars 12-inch Rotary Paper Trimmer $53.15 Make your arts and crafts time even easier with this rotary paper trimmerUnique 12 rotary countertop trimmer features a razor-sharp rolling bladeScrapbook tool has a balanced non-skid and lightweight base |
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Tap That Chopper with Bonus Cheese Grater $14.89 Chop Fruit, Vegetable, Nuts, Cheese, Herbs and Chocolate with EaseSelf-Contained Base allows for easy Chopping with or without a Cutting BoardCutting Blades Rotate with Each Press for Maximum Power and Performance |