RE: homebuilt LAMA  
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RE: homebuilt LAMA - 6/13/2008 7:08:55 AM   
RHYNO


 

Posts: 39
Joined: 10/19/2003
From: NapierNew Zealand, NEW ZEALAND
Status: offline 		Its the gearbox on the second stage that I have no info on, so don't know where to start....so was going to just buy it...

_____________________________

I''m what Willis was talking about

(in reply to wiz310)
       Post #: 26

RE: homebuilt LAMA - 6/13/2008 9:43:01 AM   
tjmackey


 

Posts: 63
Joined: 2/12/2008
From: Logan, AUSTRALIA
Status: offline 		wiz310, great info. I have used the dogbone joints from rc cars for tail drive shafts before, could you show pics of the tail gearbox, iv'e used the old hirobo tail gearbox on my projects, but id like to see your ideas on building one, this may make things easier in the future as the hirobo box is getting hard to find

< Message edited by tjmackey -- 6/13/2008 10:08:35 AM >

(in reply to wiz310)
       Post #: 27

RE: homebuilt LAMA - 6/13/2008 9:56:03 AM   
tjmackey


 

Posts: 63
Joined: 2/12/2008
From: Logan, AUSTRALIA
Status: offline 		RHYNO, the gearbox on the mw54 is just a 2 stage box, on the mw44 they use a planetary box, the mw44 puts out about 7.5 hp at 6300rpm, and has a 9 to 1 ratio. The bearings/Gearbox are lubricated by the oil/fuel mix and air bleed from the gas producer keeps them cool, Hope this info helps

< Message edited by tjmackey -- 6/24/2008 1:18:49 PM >

(in reply to RHYNO)
       Post #: 28

RE: homebuilt LAMA - 6/16/2008 4:02:58 AM   
underthefloor


 

Posts: 5
Joined: 5/18/2008
From: Portland, OR, USA
Status: offline 		Does the feathering and flapping change the gyroscopic preccesion angle? Are the controles offset by 90deg or do you have to adjust them bassed on the amount of feathering?


(in reply to tjmackey)
       Post #: 29

RE: homebuilt LAMA - 6/16/2008 1:50:20 PM   
tjmackey


 

Posts: 63
Joined: 2/12/2008
From: Logan, AUSTRALIA
Status: offline 		Underthefloor, Nothing can change the phase of gyroscopic preccesion, it will always act at 90degrees from an input. The leadlag and flapping in the multiblade system is there to allow the blades to take there natural course, to reduce stress and torque couples wich would otherwise happen in the blades. The blades have freedom to lead/lag because as a blade rises or lowers due to an input, the blade requires to speed up or slow down due to conservation of angular momentum. When a blade rises (freedom to flap) The tip of the blade becomes closer to the rotating axis, as energy is always conserved, the blade is forced to increase its speed to retain energy, if a blade lowers (remembering coning angle) The distance from the tip to the axis is increased, so the blade must slow down, The concept of conservation of angular momentum can be demonstrated by an ice skater, if they spin in a circle and then extend the arms the rpm will decrease, if they pull the arms closer to the body the rpm will increase to retain the energy disregarding friction.
On a two blade system the blades are free to teeter as a unit (as they are 180deg apart) and the high and low blade cancel each other out, however on a multiblade system such as a 3blade head, the blades are all at different stages of there cycles at any one time, so the freedom to flap indipendently and lead lag indipendantly allows them to do there job without affecting each other.

(in reply to underthefloor)
       Post #: 30

RE: homebuilt LAMA - 6/16/2008 11:50:16 PM   
underthefloor


 

Posts: 5
Joined: 5/18/2008
From: Portland, OR, USA
Status: offline 		The ability of the blades to feather as they flap means that the pitch of the blades is not directly linked to the swash.

This is how I understand it: If you move the cyclic forward, the blades will have maximum pitch at 3 oclock and a minimum pitch at 9 Oclock(assuming counter clockwise spinning). A coupled moment is applied at 12 and 6 causing the blades to flap up at 6 and down at 12. With the feathering, the pitch of the blades decreases relative to the swash at 6 and increases at 12 which should cause the heli to role slightly to the left as it pitches forward.

Im planning to convert a honey bee king 2 to flybarless without electronic stabilizing and am trying to get a better understanding of how the flapping and feathering will affect it.

(in reply to tjmackey)
       Post #: 31

RE: homebuilt LAMA - 6/17/2008 10:40:02 AM   
tjmackey


 

Posts: 63
Joined: 2/12/2008
From: Logan, AUSTRALIA
Status: offline 		Well, if the swash tilts forward, the blade at 3 will have max pitch on a clockwise system and 90 deg later when the blade is at 6, is when full deflection will occure, as in the rear of the disk will tilt up, My pitch arms on the blade grips are directly linked to the swash and the pitch arm is on the leading edge side of the blade, so when a given blade is a the 3 position the pitch arm actually receives full input from the rear of the swash which if the swash is tilted forward the back of the swash will be tilted up, giving max pitch to the 3 oclock blade, then as I said full deflection of the blade will happen 90 degrees around at the 6 oclock position tilting the disk forward. I have my swash actually around 45 degrees to allow the rods to go straight up to the blades however my phase angle is still set a 90, as in when I put forward input the 3 oclock blade receives the input.

What I mean when I say the head feathers as it flaps is, as the blade flaps up, due to the position of the flapping hinge, pitch angle is automatically reduced and vice versa, this is a function of the rotor head that helps to dampen the flapping. It does not require any extra mechanics to do this.
If you have a look at the pics of my head youll notice there are only 3 rods off the swash to the blades, and a swash driver.

(in reply to underthefloor)
       Post #: 32

RE: homebuilt LAMA - 6/18/2008 9:43:16 PM   
Eyal M.


 

Posts: 2
Joined: 7/14/2004
From: Hod-Hasharon, ISRAEL
Status: offline 		Hello guys,
I see you are interested in building Alouette/Lama. I'm scratch building a 1/4 scale Alouette II and published a build thread at - http://www.scalerchelis.com/phpBB2/viewtopic.php?f=17&t=9321

I designed and created 100% of the parts except engine, blades and standard bolts. All is made with small lathe and simple mill (even no DRO) and I do all hundreds of aluminum welding points with a simple torch.

Regards,
Eyal.

(in reply to tjmackey)
       Post #: 33

RE: homebuilt LAMA - 6/19/2008 10:37:56 AM   
tjmackey


 

Posts: 63
Joined: 2/12/2008
From: Logan, AUSTRALIA
Status: offline 		Eyal M. Looks like an ok project

< Message edited by tjmackey -- 6/19/2008 11:32:12 AM >

(in reply to Eyal M.)
       Post #: 34

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