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Lift capability of Trex 450 ?


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solentlife
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PostPosted: Thu Jan 06, 2011 11:16 pm
PostPost subject: Lift capability of Trex 450 ?
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Take a standard 450 Trex, 325 blades etc.

What additional weight would you consider it could lift ?
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Crashagain
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PostPosted: Sun Jan 09, 2011 1:05 pm
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I found this..
A typical 450-sized electric helicopter may weigh 800 grams (0.8Kg) and have a rotor diameter of 70cm (0.7m), giving a disk loading of:
0.8/(pi*(0.7/2)^2) = 2.1Kg per square meter

But my math sucks and I have no idea what that means..
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tombo242
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PostPosted: Sun Jan 09, 2011 8:39 pm
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Crashagain wrote:
A typical 450-sized electric helicopter may weigh 800 grams (0.8Kg) and have a rotor diameter of 70cm (0.7m), giving a disk loading of:
0.8/(pi*(0.7/2)^2) = 2.1Kg per square meter

But my math sucks and I have no idea what that means..


OK Crash, a quick crash course Laughing

This is taking the weight of the heli (0.8Kg) and the swept area of the rotor (pi*(0.7/2)^2) in sqM. The weight is divided by the area to produce the weight per sqM on the rotor.

Without knowing what the max lift ratio is of the rotor this does not help very much in considering payload, but I do know from experiment, that on my 450 anything over 110g (4ozs) seriously effects handling, especially in ground effect when landing. My little co-axial has (for its size) a much better and safer lifting capacity.

Tom.
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Crashagain
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PostPosted: Mon Jan 10, 2011 1:44 pm
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Nice try Tom, but I still don't understand. Even with a calculator I could not figure that out, let alone understand what all the squiggly lines mean.
I did undstand the symbol for pie, but thats it. Laughing
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tombo242
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PostPosted: Tue Jan 11, 2011 12:37 am
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Hi Crash,

Second try then. This bit (pi*(0.7/2)^2) is just the area of a circle Pi x Radius squared.

Radius is the 0.7/2 bit [half the diameter in meters] and ^2 means squared [multiplied by itself]. You could also use (pi*D^2)/4.

So that whole part is the swept area of the rotor in meters squared. The bigger the swept area the bigger the lift for constant rotation speed and pitch.

This heli is, of course only lifting itself! Not much good if it couldn't what it does not tell us is at what power level is it doing this and how much it can be increased.

Tom.
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chopper54
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PostPosted: Tue Jan 11, 2011 4:06 am
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if you dont understand the squiggly lines ( i dont either) just keep adding weight until the heli crashes and then you will know you have over done it and remove a bit.
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Crashagain
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PostPosted: Tue Jan 11, 2011 1:14 pm
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You tried Tom, but sorry to say it's just not working. I think I am to old to learn this stuff. You know what's funny though is I use numbers all the time at work, by measuring and squaring things. I can tell you the center of almost any measurement off the top of my head, but the rest of my math sucks..
chopper, your idea is more the way my thinking is.. Laughing
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tombo242
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PostPosted: Tue Jan 11, 2011 8:14 pm
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OK Folks, I give up on that one.
Can't beat the good old "Try it and See!" method.

Tom.
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chopper54
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PostPosted: Wed Jan 12, 2011 5:27 am
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my maths skills
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solentlife
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PostPosted: Wed Jan 19, 2011 10:57 pm
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There's a Youtube vid of a guy lifting a bag of Oranges with a 450 .....


Link


mmmmmm it lifts but it's so quick that I feel a time required on lift should be applied or able to complete a height / area flight ?

But kg's of oranges !!

My question was based on a query from another to me about what I thought it could lift in terms of camera ( it's always that camera isn't it !! )

So as I understand it .... up to 200gr is OK ... over that is iffy. But significant battery power is consumed in doing it. My 16gr Keycam is no problem and would not alter battery time noticeably.
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tombo242
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PostPosted: Thu Jan 20, 2011 1:49 am
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That's not a lift it's a wee hop, not sure that the bag cleared the top of the grass. I agree it should lift the load at least 2M (6' 6.75") high and hold it up there for a minimum of 2 mins.

Tom.
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