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It is basically about what you are trying to lift, for a certain radius each blade will give a certain amount of lift, so if you have a small light helecopter 2 blades will be fine, the heavier the helecopter the more blades are useful. the more blades you have the more complex and expensive the rotor is so you probably want as few as possible. Really big helecopters have more blades eg the CH53 has 6 bladeshttp://en.wikipedia.org/wiki/CH-53KSome more modern helecopters have odd numbers of blades which I think is harder to build but quieter
I went in one that had 5! Can't remember the make -could have been a Harris(?)There is an issue of tip speed; it mustn't approach Mach 1 or you get turbulence, damage and inefficiency.Several short blades give you similar lift and you can rotate them faster.Why doesn't anyone make a modern Chinook?
is Mach 1 the big no no then ?
Let's have a brrrrrr too.
If you had like 8 blades on a light chopper.. What difference would it make than the same light chopper with 2 blades?
In terms of blades, I don't know; if we can assume that a blade moves only a relatively small portion of the available air, adding blades while keeping speed and diameter the same would increase the volume of air moved and thereby increase lift. However, there could be interactions between the air movements, particularly if the number of blades becomes such that the distance between adjacent tips is significantly less than the radius, which might result in diminishing returns from adding blades beyond a certain number.
if you want lots of blades you could always buy one of these[attachment=672]Or if you cant afford the above Kamov Ka-52 "Alligator
Quote from: ukmicky on 17/09/2007 22:15:21if you want lots of blades you could always buy one of these[attachment=672]Or if you cant afford the above Kamov Ka-52 "AlligatorNice toy. Is it made that way to reduce noise or what?
QuoteNice toy. Is it made that way to reduce noise or what?The two sets of blades are rotating in opposite directions so the craft is more stable and has less vibration.With one set of blades you need a rear side stabilizer to counter the effects of rotation drag.As in the photo there is no rear stabilizing side rotor as it don't need one, just change the speed of a rotor to rotate.
Nice toy. Is it made that way to reduce noise or what?
but if you reeeeeeeeeeeally want an anwser then you could read this.http://www.kamov.ru/market/news/petr11.htm
what about jet engine blades...they spin well fast don't they ?