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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
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 The rotor blades are
connected up to the joysticks and collective pitch levers.
The tail rotor has collective pitch control made from plates with clips.
http://www.brickshelf.com/cgi-bin/gallery.cgi?i=1437015
The model is not quite finished but these pictures show some of the inside
workings. The swivelling front camera, rocket launchers and missiles are all
there. I haven't finalised the full length rotor blades yet, but the trial ones
drooped a bit as their length means they almost touch the tail.
Both the main rotor and tail rotor use the swash plates supplied with 8856
helicopters. The collective and differential pitch control adds the two signals
together in the rotor tower using levers. I modded a few bits so that the crank
mechanisms would fit in the bottom of the tower. I think these include my
shortened axle pins (cut the pin off one leaving an axle and a bezel with the
total length being 8mm).
I had intended to put two 12V train motors behind the main rotor, since it needs
a lot of power to turn it, but the new RC car motors should do just as well once
I have enough of them.
I used black in the absence of enough cammo coloured bricks. The parts I used
for the undercarriage are fatter than scale because of the weight. I knew axles
wouldn't be strong enough so I had to use beams. I might change these for
studless ones later, to reduce he profile.
PLMKWYT
Mark
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On 22/10/05, Mark Bellis <mark.bellis@tiscali.co.uk> 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
>
> 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 The rotor blades are
> connected up to the joysticks and collective pitch levers.
>
> The tail rotor has collective pitch control made from plates with clips.
> http://www.brickshelf.com/cgi-bin/gallery.cgi?i=1437015
>
> The model is not quite finished but these pictures show some of the inside
> workings. The swivelling front camera, rocket launchers and missiles are all
> there. I haven't finalised the full length rotor blades yet, but the trial
> ones
> drooped a bit as their length means they almost touch the tail.
>
> Both the main rotor and tail rotor use the swash plates supplied with 8856
> helicopters. The collective and differential pitch control adds the two
> signals
> together in the rotor tower using levers. I modded a few bits so that the
> crank
> mechanisms would fit in the bottom of the tower. I think these include my
> shortened axle pins (cut the pin off one leaving an axle and a bezel with the
> total length being 8mm).
>
> I had intended to put two 12V train motors behind the main rotor, since it
> needs
> a lot of power to turn it, but the new RC car motors should do just as well
> once
> I have enough of them.
>
> I used black in the absence of enough cammo coloured bricks. The parts I used
> for the undercarriage are fatter than scale because of the weight. I knew
> axles
> wouldn't be strong enough so I had to use beams. I might change these for
> studless ones later, to reduce he profile.
>
> PLMKWYT
>
> Mark
Nice. I would love to see a close up of the rotor gimbal. I cant wait
to see it completed.
I find myself wandering about the best way (if any) to get a rotor
blade with a proper wing like structure in Lego.
Something using the 1x1 with a tooth, snot techniques and then some
paper might get somewhere close - a small frame with paper "skin".
Sure introducing paper is not purist, but I am not sure what else I
can think of.
Danny
--
http://orionrobots.co.uk - Build Robots
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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
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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! :-)
Mark
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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! :-)
>
> Mark
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. This was the main reason I sent TLG the photos, as if to say "Come
on, you've made the parts, now give us a proper helicopter!". At the time, I
sent a whole film of various train and technic stuff, including the pick and
place robot, now well documented on my Brickshelf, and a roverbot powered by two
12V train motors, then the most powerful LEGO motors available.
I'm not sure whether I will finish the Apache, since I built it as a demo for
the rotor mechanism, expecting that no-one would understand the mechanism
without the rest of the helicopter! I need more of the new RC car motors before
I can continue, due to the power required to rotate the blades, but I have so
many other projects on the go that it's not the greatest priority. The model
has been in its present form for a few years as I've been busier with trains!
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!
I found with the 8856 helicopter that the splined ball piece didn't have as much
grip on an axle as most other parts with axle holes, so I thought I'd weaken its
grip a little further - enough to allow it to slide to achieve collective pitch
variation. This worked well on the main rotor so I made another one for the
tail rotor.
The weight of the rotor with trial blades is so great that the swash plate
bearing certainly needs its wishbone pieces on all four sides, rather than just
one and a flex cable like the 8856 set.
http://www.brickshelf.com/cgi-bin/gallery.cgi%3Fi%3D1437013
I remember that, as soon as I had two 8856 helicopers and an 8865 Test Car, I
built a four wheel drive car, but the swash plates weren't strong enough to hold
the front wheels on round corners! I guess TLG had the same problem, which is
what led them to make different parts for the VX4 Supercar 8880.
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.
I had thought the steering parts from the smaller trucks with suspension, such
as the Dakota Wrecker, were pretty useless till I found this application for
them - four to link the swash plate to the blades.
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!)
Following the example of a motor glider in one of the Technic ideas books, and
the sails in various ship sets, I could look into making paper or acetate blades
to save weight and increase aerodynamic efficiency (LEGO plates weren't designed
for that!), but I was reluctant to use non-LEGO parts.
I like your Huey Ross, it is well deserving of the prizes it won.
Mark
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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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Was it possible to make a functional, FLYING helicopter with Meccano/Erector?
(for those who did play with this metal based, building toy)
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