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Old Dec 10, 2012, 04:07 PM
James not bond
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United States, MN, Minneapolis
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fixed pitch heli header

I came over from multirotor... my thought is that multirotor is somehow performs similar to heli rather than airplane.. but we have been using airplane prop for a long time.. I'm thinking what if we use heli blade on multirotor..


so here comes the question.. where can i find a simple (adjustable) fixed pitch header to try out?

any suggestion and advice is appreciated
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Old Dec 10, 2012, 04:41 PM
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You might be able to use this as a start, it's a variable pitch prop system for a plane:

ElectriFly RC V-Pitch Variable Pitch Prop System w/Motor (1 min 6 sec)


I don't think it ever caught on, but I've always thought it was awesome. I don't know if the company that makes them are still around... in fact I know nothing about the system itself other than it exists.

A variable pitch quad would be cool. Then again, anything variable pitch is cool .
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Old Dec 10, 2012, 05:44 PM
James not bond
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variable pitch will be the next thing..since for now.. i pretty much prefer to have it fixed.. so i will not need extra control .... but it will be some day down the road


thx
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Old Dec 11, 2012, 01:07 PM
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my bad, I somehow thought variable pitch was what you were looking for, even though you did clearly state fixed pitch.

I don't get what you're trying to do, isn't a quad already fp? But you want an adjustable pitch? That's variable pitch. Most fp helicopters have 5 degrees pitch on the blades, that's not adjustable (the angle). If you want adjustable, by definition you have to go variable pitch... it doesn't have to be a more complicated collective pitch system (like a heli)... just something you can adjust the blade angle of attack, no?

If all you did was change a quad prop for a heli head & blades (both being made of the same materials) at the same fixed angle, it wouldn't fly a whole lot different. Having said that, there are a ton of variables that could effect flight either way, in that scenario.
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Old Dec 11, 2012, 01:20 PM
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I'm not sure, but I think he's looking for a set of blade grips/holders for an FP that could be mounted on a quad so he can use blades from an FP heli? I'm pretty sure that would require reduction gears as well.
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Old Dec 11, 2012, 01:25 PM
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What would be the purpose? If done properly, it wouldn't fly any different than it does now.

If that's all he wants to do, I don't understand the request for it to be adjustable.
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Old Dec 11, 2012, 01:47 PM
James not bond
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let me try to clarify

I might mix the concept.. but here's what i want to do

1. an adjustable header.. for manually fixing the pitch before flight.. but in flight the pitch will be fixed
the purpose is to test a pitch vs rpm (in comparison with airplane prop that i can find)
also cuz the blade pitch counts a bit different from airplane prop.. so I want to see how to make the equivalent.


2. the blade+holder will be mount on outrunner motor.... rpm is controlled by esc/throttle so literally reduction gear is not necessary


3. the main diff between airplane prop and blade (seems to me) is that blade has a uniform pitch throughout from root to tip; but airplane prop is changing larger close to root and smaller (close to 0) at the tip

but apparently heli blade is made for vertical take off/landing.. it makes sense that using heli blade could make difference from airplane prop...

and i want to test out how much difference will it be though


btw... the prop blades are usually 200mm+.. is there any blade at around 100mm? ( so i can make up a close to 12" prop)


much appreciated
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Old Dec 11, 2012, 02:21 PM
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rcplanes hover

I see what you're saying, and it's interesting. I think I'll watch this thread and see what you come up with.

However if you used a variable pitch prop system (x4, means $$$), similar to the one I posted you could set your pitch curve flat to whatever angle you wanted and keep it at 5, or 6, or (x) degrees the whole flight.

FP blades are set at 5 degrees because it provides for a stable hover, if pitch were much higher or lower I would expect it to be less stable overall, at least in low rpm, or maybe unsafe in higher rpm. I'm not a scientist obviously though.

So the point is to get a quad to fly better? Cool.

12" prop x4, holy moley!

Ever try a collective pitch heli?
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Old Dec 11, 2012, 02:26 PM
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FYI I have a helimax fp nano (walkera 4#3) that blades & head together measure 200mm.
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Old Dec 11, 2012, 03:48 PM
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The only adjustable pitch FP head was found on the Hirobo SRB Quark. It was quite expensive and is now, very difficult to find.
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Old Dec 11, 2012, 03:54 PM
James not bond
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so the easier approach is to buy variable pitch.. and find a way to fix it at a certain angle?
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Old Dec 11, 2012, 05:25 PM
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The VP pitch system used by planes, as posted by finguz, is the best option. Just omit the servos and secure the linkage to something so the pitch can't change.
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Old Dec 11, 2012, 07:47 PM
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Good idea on fixing the pitch balr14! Or use a 4 way servo splitter programmed into one channel, controlling the pitch (or fixing it in your tx). Though I've never done it and don't know if it's possible.

Or what about using 4 variable pitch heli tails? Like on a 450 trex, or whatever size works. You could use a 4 way servo arm with 4 ball links controlling pitch together. Still you have some engineering to do. The more I think about it, the plane variable pitch system I posted would be easier, because you still have to fabricate something similar to how it changes pitch.

To stay with your fp idea, your other option would be to find 4 coaxial heli blade grips that fit your motor shaft, two sets might have to be "bottom" coaxial blades and the other the "top" blades (As on a coaxial the 2 sets of blades spin and provide lift oppositely). Which this may be your best shot, now that I think about it... But you're stuck with a fixed 5 degrees, which isn't so bad, it's how fp helis fly, and similar to how your quad flies... but it would have heli blades like you wanted . My syma s109 rotor disc is 180mm.

Good luck, whatever you do keep us posted.

Balr, I think you're a quad guy, right? There's not a vp quad out yet?
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Old Dec 12, 2012, 12:36 AM
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The brand Blade's mqx quad props aren't twisted like a plane prop... maybe they'll fit your quad, they're 140mm rotor diameter so maybe not.

I was recently thinking of buying a mqx bnf for $120, but I'm still on the fence about it.

Here's a pic of the mqx clockwise blades:
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Old Dec 12, 2012, 08:09 AM
James not bond
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hmmm good idea... i will take a look at that

thx
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