Subject:
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Re: 1:20 scale Apache Helicopter
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Newsgroups:
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lugnet.technic
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Date:
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Sun, 23 Oct 2005 21:55:25 GMT
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Viewed:
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9161 times
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In lugnet.technic, Mark Bellis wrote:
> In lugnet.technic, Mark Bellis wrote:
> > In lugnet.technic, Ross Crawford wrote:
> > > In lugnet.announce.moc, Mark Bellis wrote:
> > > > Here's my MOC of an Apache helicopter, built to 1:20 scale, compatible with
> > > > Technic figures. http://www.brickshelf.com/cgi-bin/gallery.cgi?i=1437017
> > >
> > > Looks like it's going well! Can't wait to see the finished model! But...
> > >
> > > > It features the first ever fully working Lego helicopter rotor with collective
> > > > and differential rotor blade pitch control.
> > > > http://www.brickshelf.com/cgi-bin/gallery.cgi?i=1437013
> > >
> > > Sorry mate, but I already had that in 2000 with my first model after my "dark
> > > ages": http://www.br-eng.info/about/lego/mocs/huey.htm
> > >
> > > Implementation is a little bulkier, but I didn't mod any parts ;)
> > >
> > > Regards
> > >
> > > ROSCO
> >
> > Sorry, the rotor was done in 1996 - TLG have the pictures! So mine was the
> > first after all! :-)
D'oh! But I can still say at least mine didn't have any modified parts ;)
> Anyway, I'm glad I'm not the only one to have tackled this problem. As soon as
> I bought an 8856 helicopter http://www.brickset.com/search.aspx?query=8856 I
> thought "That's not how a real helicopter works" and began thinking how to do it
> properly.
> Originally, back in 1996, had intended to build a Chinook, thinking "why not
> make another rotor the same now that it works well", but a Chinook has only 3
> blades per rotor, not compatible with the 4-way swash plate, and in a mock-up I
> found that it was difficult to put the strength in the body, so the Apache was
> more feasible, particularly as I found a leaflet about it, with good pictures,
> in a magazine. It still didn't have scale drawings though, but I can't expect
> to get those since it's a military vehicle!
Actually, the swash plates on a chinook are a bit simpler - they only require
collective and roll control, pitch is handled by differential collective on the
2 rotors. But the difficulty of doing 3 blades with LEGO does more than balance
out that added simplcity.
> Another problem to overcome in the Apache was the weight of the blades and the
> consequent centripetal force as they rotated even at a modest speed. That's why
> the pivots for the blades are so far from the centre of the rotor.
Yes that is a big problem, and mine also pivoted a fair way from the centre.
> There's plenty of ability to pivot the whole rotor just with flexing of the main
> axle, so a separate pivot wasn't necessary. It should only pivot to hang the
> weight of the body below it when flying (which a LEGO one without custom parts
> never will!)
Actually, that pivot (called "flap") is mainly required to help reduce the
dis-symmetry of lift associated with wind and forward motion - it is described
in detail on this page I found while building the huey:
http://www.helicopterpage.com/
> I like your Huey Ross, it is well deserving of the prizes it won.
Thanks! Disappointed to hear you won't be completing the Apache though :(
ROSCO
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Message has 1 Reply:
Message is in Reply To:
 | | Re: 1:20 scale Apache Helicopter
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| (...) Anyway, I'm glad I'm not the only one to have tackled this problem. As soon as I bought an 8856 helicopter (URL) I thought "That's not how a real helicopter works" and began thinking how to do it properly. This was the main reason I sent TLG (...) (21 years ago, 23-Oct-05, to lugnet.technic)
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