Go Back  RCU Forums > RC Helicopters > Electric RC Helis > T-Rex heli
Reload this Page >

Rotor head question

Notices
T-Rex heli For all you T-Rex lovers out there, this where you can post!

Rotor head question

Old 02-12-2007, 09:40 AM
  #1  
ksechler
Senior Member
Thread Starter
 
Join Date: Sep 2002
Location: Frederick, MD
Posts: 506
Likes: 0
Received 0 Likes on 0 Posts
Default Rotor head question

What's the difference between a bell-hiller and a CCPM rotor head? Any advantages to either one?
Old 02-12-2007, 02:41 PM
  #2  
soop7667
Senior Member
 
soop7667's Avatar
 
Join Date: Jan 2007
Location: Cape Coral, FL
Posts: 475
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rotor head question

I'm not sure If I have this right or not, but I think you might be comfused - or maybe I am. Bell hiller, I think, is the whole swash plate mixing thingy.

I will tell you of what I DO know. CCPM = Cyclic Collective Pitch Mixing
My MX-400 has a swashplate that has 4 linkages that go to the top side, (The flybar and the blade grip linkages), and 4 linkages that go to the bottom side - The elevator control linkages, and the aleron control linkages. These elevator and aleron control arms are mounted on an assembly which slides, (my means of a servo actuating an arm which pivots) up or down on the main shaft. In simples terms - the whole assembly moves the position of the control arms up and down all together by using one servo to move the assembly. To increase the collective pitch in a positive degree - it slides all of the linkages up together, and to produce negative pitch - it slides the assembly down. In this example the CCPM functions by means of a mechanical linkage system.

On my T-Rex 450 SE, it has an eCCPM type swashplate - that is - The CCPM Functions by means of mixing electronically in the transmitter. The swashplate has the same 4 linkages that go to the top side, (The flybar and the blade grips), however on the bottom it only has 3, as opposed to the 4 found on the mechanical CCPM system. The three points of the swash has one in the rear, and two in the front - (One on the left side of the front, and one on the right side of the front.) These threee points don't link to an assembly of control arms - they link directly to three individual servos. The servos potitions are mixed together in the transmitter - If you want to go left - it tilts the right side up, and the left side down - tilting the swashplate to the left. Right = Right respectively. To tilt forward it raises the rear and moves both of the fronts down together. And rear works just the same - opposite movements of coarse. To increase the collective pitch - All three servos move up together, and down all threee move down together.

In conclusion, the basic difference in these two type of CCPM are this - In the first Example - the Pitch is controlled using a mechanical linkage (Mechanical CCPM) , in the second - the pitch is controlled using a combination of movements by servos which signals are mixed electronically, rather than mechanically - (Electronic CCPM)

Hope I helped!
Old 02-12-2007, 03:35 PM
  #3  
BarracudaHockey
My Feedback: (11)
 
BarracudaHockey's Avatar
 
Join Date: Jul 2003
Location: Jacksonville, FL
Posts: 26,913
Received 339 Likes on 271 Posts
Default RE: Rotor head question

Bell hiller means it has a flybar.

CCPM or non CCPM is a way of controlling the swashplate and only appies to swash on down.
Old 02-12-2007, 03:55 PM
  #4  
endeavor_635650
Member
 
Join Date: Apr 2003
Location: Moultrie, GA
Posts: 91
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rotor head question

So are you comparing the Trex HDE (mechanical CCPM) to the CDE/SE (electronic CCPM)?

Mechanical CCPM is set up so that one servo controls one function i.e. one servo for roll, one for pitch(forward/backward), and one for collective. eCCPM (electronic CCPM) uses three servos mixed together in your Tx to control roll, pitch, and collective.

Mechanical CCPM is popular with some of the heli pilots that have been in the hobby for a long time, I think because this setup is what they are accostomed to and it is sufficient for their flying style consisting of light aerobatics. eCCPM is popular among the 3D pilots because of its simplicity and its strength. eCCPM distributes the cyclic/collective load between 3 servos, reducing the amount of work done by each servo. This produces a heli with that has a lot of servo holding power on the swashplate, giving you better control and making it perfom much crisper while doing aerobatics.

To sum up, I'd say go with eCCPM. I think you'll be happy you did, even if you never get into the 3D scene. It seems to be the direction that most manufacturers are now going too.

Brian
Old 02-12-2007, 08:10 PM
  #5  
Dynamic
Senior Member
 
Dynamic's Avatar
 
Join Date: Sep 2006
Location: , BC, CANADA
Posts: 143
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rotor head question

ORIGINAL: BarracudaHockey

Bell hilller means it has a flybar.

CCPM or non CCPM is a way of controlling the swashplate and only appies to swash on down.
The blade CP (not cp pro) does not have the bell hiller however it does have a flybar. How about lets describe what the bell hiller mixing is actually about.

With a regular hiller mixing system cyclic pitch variations of the main blades are then controlled entirely by the tilting of the flybar. There is latency between the tilting of the flybar and the tilting on the main rotor. With the bell hiller mixing however in addition to inputs to the flybar input is also directly made to the swash tilting the main rotor immeadiatly eliminating the latency and making your helicopter more responsive.

If you want to take the mystery out of how your helicopter actually works, and why one way is better then the other Collin Mills has an excellent article here
http://www.w3mh.co.uk/articles/html/csm9-11.htm
(mixing is about half way down the page....yes there are pictures)

CCPM refers to the ability to control cyclic with a floating swash. As your pitch up or pitch down your swash will slide up or down your mainshaft, regardless of its vertical postition on the mainshaft the swash plate is still able to provide cyclic control on its horizontal plane. If your heli does not have CCPM your swashplate will need to remain in a fixed vertical postition on your main shaft. In a non CCPM system you will have 2 servos conected to the swash that will provide cyclic control and one servo that will control pitch independantly of the swash. With CCPM 3 servos control the swash in both a vertical and horizontal plane. CCPM allows for more precise inputs and a consistant input throughout the entire pitch range however your TX must support CCPM as your TX will be responsible for mixing the servo inputs. With CCPM 1 stick movement (on one axis) can move 1, 2 , or 3 servos depending on the input and this is controlled by the TX. Without CCPM 1 stick input only controls 1 servo. The CCPM system allows for smoother more consitant inputs through out the entire pitch range. In addition in 3D flight you will get better pitch performance as you have the strength 3 servos holding your pitch instead of 1.

Hopefully that will clear up some of the mysterious terminology involved with your helicopter.
Old 02-13-2007, 08:49 AM
  #6  
ksechler
Senior Member
Thread Starter
 
Join Date: Sep 2002
Location: Frederick, MD
Posts: 506
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rotor head question

Thanks guys, and yes, I was comparing TREX models. I got tired of my Blade CP Pro's wagging tail and decided to upgrade.
Old 02-13-2007, 10:56 AM
  #7  
ct420
Senior Member
 
Join Date: Mar 2006
Location: mansfield, TX
Posts: 1,195
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Rotor head question

The standard Blade cp head has the hiller design.

The upgrade head is bell and hiller (often shortended to bell-hiller)

On a hiller system, cyclic changes are sent via links from the swash plate to the flybar assembly. The flybar assembly, in turn, has links to the blade holders. Therefore, the servos must move the flybar, then the rotor 'catches up'

On bell and hiller, cyclic changes are sent via links to the flybar and also to the blade grips simultaneously by adding some links to it that the standard hiller design does not have. The flybar is still connected also, but now the swash plate movements are sent to the flybar and rotor directly. This design offers faster cyclic changes than standard hiller.

Some bell-hiller heads have adjustments so you can vary the amount of force coming from the flybar to the rotor vs. the swash to rotor. This lets you 'speed it up' or 'slow it down' somewhat.


CCPM and eCCPM has nothing to do with hiller vs. bell-hiller. That is another topic entirely, which as already been covered in previous posts from others...

HTH

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.