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e-Century Hummingbird - Swift > CP: more negative collective problem solved
 
 
zoom
Elite Veteran
Location: Galveston, Texas

My Posts This: Topic  Forum		Someone stated that they only got -2 degrees out of their CP and was feeling cautious about inverted flight. I love electics because you can always modify them. Here is my solution that I will employ as soon as I get time. Meanwhile those of you who can't wait on the report from my experiment, here you go.

The CP's negative collective is limted by 2 things:

1. The main shaft ring collar that contains the set screw.

2. The main shaft head where the flybar negative range is shortened by the vertical slit on the side of the head.

Solution part 1: If you want more negative collective all you have to do is file the main shaft collar ring down atleast 1mm on each side. This will allow the swashplate more negative travel providing more negative collective.

Solution part 2: As mentioned earlier, negative collective is also limited by the vertical slit on each side of the main shaft head. Just take your dremmel tool and cut more of a slit downward on the main shaft head. The important things to remember here are:
Don't go too deep with the slits, and the pair of slits that allow the flybar deflection must be lower than the slits that allow negative travel.

Of course the disclaimer: This experiment has not been carried out by myself just yet, and is only theoretical at this point, so do it at your own risk. However, I will perform this experiment as soon as I get a chance. I think it will work. I just can't live with only -2 degrees.

Predator, Raptor 30, TRex CCPM 450TH, 3D Pro 400F
05-14-2004 Over year old.
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pbmax
Key Veteran
Location: Olympia, WA - USA

My Posts This: Topic  Forum		I don't think I'll be modifying that slit any time soon - it's wobbly enough as is, and with even less structure I imagine it'll be worse.

How about going with higher head speed and less positive pitch? Meaning, adjust the pitch links to allow for a better proportion of negative to positive pitch. With a higher head speed (bigger pinions possibly) you'll get just as much lift from less positive pitch, and better negative thrust from more negative pitch, possibly enabling inverted flight. Before I destroyed my century symmetric blades, I did something similar to this and got enough negative pitch to throw it at the ground in a hurry. I imagine it's enough for rolls and short loops, but probably not enough for inverted flight.

Right now for me, it's the nut behind the wheel that's the limiting factor, not the heli itself

pbmax
05-14-2004 Over year old.
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zoom
Elite Veteran
Location: Galveston, Texas

My Posts This: Topic  Forum		Thanks for the post PB,

I definitely agree with that part about it being more so the pilot and not the heli. It is certainly so in my case, but to compensate for any lack of 3D skills on my part, I have to take a shot at modifying my CP Hummer.
I'll try to be as precise as possible.

I thought about the higher head speed thing as it will be the case after installing the 2015/4100. It is definitely a good alternative. I just prefer not to solely rely on it. I have completed the wood blade root preparation with epoxy as I described in another post and will be checking the for balance later. The only problem I have ever had with the wood blades was that of tracking, but as far as a higher head speed, these blades will definitely be up for the task.

The reason I won't depend on head speed alone is that, running wood blades are hardly ever as efficient as composite blades there for placing the motor under greater strain is not the best option for me. The ideal setup for me is where my motor and batteries run cool. It may not go as planned, but I'll definitely be shooting for it.

I will not be satisfied with just quick rolls and loops (at high altitudes). I mean, I just been waiting way too long for the collective pitch Hummer to come out. I'm talking mad inverted climb outs are what I'm looking for. Or, if it flies atleast flies as well as the video on the Zoom 400, I'll be satisfied.

These mods are of course are all experimental and I have pinions from 9T to 13T. I will not stop tinkering until my CP is all that It can be. Oh yeah, I'll be sure to post a vid demonstating these manuevers if I can only get the wife to cooperate.

Predator, Raptor 30, TRex CCPM 450TH, 3D Pro 400F
05-14-2004 Over year old.
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zoom
Elite Veteran
Location: Galveston, Texas

My Posts This: Topic  Forum		?

Hold up guys, after applying my pitch gauge, I started seeing some weard numbers as far as pitch is concerned. Let me get this thing fully setup and I'll get back to you all. I may have to get a smaller pitch gauge. This one from Miniature Aircraft appears to be too big.

Anybody getting any different numbers as far as pitch is concerned?

Predator, Raptor 30, TRex CCPM 450TH, 3D Pro 400F
05-14-2004 Over year old.
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wilsonj
Senior Heliman
Location: Waikerie, South Australia

My Posts This: Topic  Forum		I haven't got my CP hummer yet, still waiting... But from the pics posted around the place it appears to me that you may also be able to shorten the link (part 209) going from the seesaw to the blade grip. By shaving some plastic off the ends of the ball links this should allow them to turn in further. Effectively reducing their length. This will allow for more negative, but at the expense of positive. Unfortunately no-one has posted any hard numbers on pitch range, just that it doesn't have enough negative.

The other solution may be to move the ball on the blade grip in further. This will of course also effect the way the heli responds in wind. Anyone know what size ball is on the blade grip?

Looking forward to getting my CP and experimenting myself.

Regards

Jamie Wilson
05-14-2004 Over year old.
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coolice
Key Veteran
Location: Northamptonshire, England

My Posts This: Topic  Forum		Hi Guys,

This is one thing I'm dying to get my little CP to do, inverted in the living room

A little tip I've heard, but not tried yet, is to fit Elite FP blade grips.
Apparently the ball to centre distance is closer, affording us more pitch range as has been suggested in the post above.

Ian Contessa
UK Century Sponsored Flier

Ian Contessa
Team Robbe SchluterUK
Midland Helicopters
05-15-2004 Over year old.
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wilsonj
Senior Heliman
Location: Waikerie, South Australia

My Posts This: Topic  Forum		The problem with moving the ball on the grip in, is it changes the flybar mixing ratio. How this will effect its flight is yet to be seen. I would think it would want to lean into the wind though...

Regards
Jamie Wilson
05-15-2004 Over year old.
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Hoverup
Elite Veteran
Location: Gulf Coast

My Posts This: Topic  Forum		Well the solution to the pitch range on the CP Elite is available off the shelf. Buy a low profile CNC shaft collar from www.deeteeenterprises.com and the CNC head block from Century.................


Cheers - Boyd
AMA 80393
IRCHA 3355
Major USAF
Retired
05-15-2004 Over year old.
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wedge
Elite Veteran
Location: Victoria BC, Canada

My Posts This: Topic  Forum		Dont you guys think its kinda stupid that they just came out with this CP HB and they already got upgrades for it. Like they already new of the shortfalls of it, I know its only $99 but come on, its like they planned it.


Will
05-15-2004 Over year old.
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wilsonj
Senior Heliman
Location: Waikerie, South Australia

My Posts This: Topic  Forum		Whats new!? Upgrades are a part of this hobby!

Also consider that not everyone wants to go inverted, just because its collective pitch. I am sure that the stock machine would be more than capable of rolls and loops without pitch range mods. If nothing else it is going to be an easier machine to fly upright than the FP version. And the stock setup will be sufficient for most flyers.

Just my 2c.

Regards
Jamie Wilson
05-15-2004 Over year old.
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zoom
Elite Veteran
Location: Galveston, Texas

My Posts This: Topic  Forum		Wilson,

You definitely have a point, I would just like to use this machine to train myself into 3D. Just to advance my learning curve. Until then it should be a much more fun machine.

But then again I could do that with my raptor 30, but the micros are so much fun

Predator, Raptor 30, TRex CCPM 450TH, 3D Pro 400F
05-15-2004 Over year old.
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Billy Zimmerman
Key Veteran
Location: Rainier Oregon

My Posts This: Topic  Forum		i got my CP hummer last night, your right not much negative, but loops and rolls for a micro electric to me is fine until they come out with the 3D links, i cant wait till i get my crystal to find out how she flies, is 0-25-50-75-100 a good pitch curve to start out with? what about throttle for this little thing? first serious electric heli, i have a couple raptors but this thing is different lol

Raptor 90 SE YS91,Tiger50 OS50 Hyper, Vblades, OS&YS engines, Hitec Eclipse7
05-15-2004 Over year old.
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coolice
Key Veteran
Location: Northamptonshire, England

My Posts This: Topic  Forum		Hi,

My suggestions with the CP Hummer is to have the head speed quite high. When I first started messing about with it in the living room it was very wallowy on the cyclics. But then once outside I had a chance to wind it up more and it feels so much better.

My suggestion to you is to start with about 65% throttle at mid stick and adjust from there.

Out of the box the CP flys very well, but like everything the right modifications can make it even better. Or in the case of the head block smoother.
The drawback is if you crash it quite hard I'm sure either the block will twist slightly or because it's stronger it will break more parts.

Ian

Ian Contessa
Team Robbe SchluterUK
Midland Helicopters
05-15-2004 Over year old.
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nofuelheli
Senior Heliman
Location: Roanoke VA, Usa

My Posts This: Topic  Forum		I took the bulky shaft collar of right away. Waiting on my aluminum head . I could see an improvement in negative pitch range once the low profile collar was instaled. Not to mention the stock unit is heavier. With the paper guage i am seeing -5 after the lo-pro collar. ONly had a reading of neg 2 with stock. Paper is not very accurate though.
05-16-2004 Over year old.
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zoom
Elite Veteran
Location: Galveston, Texas

My Posts This: Topic  Forum		http://www.deeteeenterprises.com/NS...ly.Upgrades.php

I checked on that small collar from DeeTee
$17 is too much for me. I can file off 1mm of each of the stock's 5mm with my dremmel and get it down to the 3mm collar that deetee is selling for $17 not including shipping.

Predator, Raptor 30, TRex CCPM 450TH, 3D Pro 400F
05-17-2004 Over year old.
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zoom
Elite Veteran
Location: Galveston, Texas

My Posts This: Topic  Forum		Here are my numbers w/ CNC head upgrade but w/stock collar (unmodified)

I got a Positive 11.5 and Negative 6.5

The positive pitch seems fine for now, but the that bulky stock collar does seem inhibit further negative travel. I just wanted to have these numbers documented prior to my 'Dremmel Appointment'.




I may be able to get away with just shaving the collar.

Predator, Raptor 30, TRex CCPM 450TH, 3D Pro 400F
05-19-2004 Over year old.
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tman52804
Senior Heliman
Location: Davenport, IA

My Posts This: Topic  Forum		zoom,

Where did you get that pitch gauge?
05-19-2004 Over year old.
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Hoverup
Elite Veteran
Location: Gulf Coast

My Posts This: Topic  Forum
Quote 
I checked on that small collar from DeeTee
$17 is too much for me. I can file off 1mm of each of the stock's 5mm with my dremmel and get it down to the 3mm collar that deetee is selling for $17 not including shipping.

Zoom


You got the price for a pack of two collars as used on my CH-47 SeaKnight twin rotor heli. The real price for the best shaft collar availble for 3mm shafted helis is Part # E067a $8.99

http://www.deeteeenterprises.com/NS...CP.upgrades.php

Cheers - Boyd
AMA 80393
IRCHA 3355
Major USAF
Retired
05-19-2004 Over year old.
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zoom
Elite Veteran
Location: Galveston, Texas

My Posts This: Topic  Forum		Rick's has a couple that I liked. When I got mine, I was actually trying to order the vario, but accidently ordered the MA. As you can see, I had to take my dremmel to this one (trimming the pinchers to grip smaller blades as well as removing other material to see these small flybars) just for the sake of this CP Hummer. But I would not be Zoom if I did not have anything to modify.

MA
http://www.ronlund.com/Merchant2/me...uct_Code=MA0526

Vario
http://www.ronlund.com/Merchant2/me...ct_Code=VAR10_4

If these links give you trouble, just cut and paste the in the web address window.

Predator, Raptor 30, TRex CCPM 450TH, 3D Pro 400F
05-19-2004 Over year old.
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zoom
Elite Veteran
Location: Galveston, Texas

My Posts This: Topic  Forum		Dremel to the rescue, as promised.



1. disassembled main shaft to get to the collar which measured about 5-6mm



2. filed it down with the dremel to 3.63 mm (lower profile saved $17 if considering ordering the 3mm collar from DeeTee)



3. As stated above in the previous post, with stock collar and Century CNC head, I got +11.5 and -6.5 with a total pitch range of 18 degrees. And that was with the vertical slits of the CNC head measuring 8.6mm. Truthfully in retrospect, I could have stopped here since the total travel was 18 deg, shortened the ball links at the blade by 2mm using cutoff wheel on the dremel, adjusted them to where I would get +9 and -9 and called it a day without even touching the head. But I did not think of that until it was all said and done .



4. So, on to dremeling out the head. I opened those slits that limit flybar travel to ~11mm



5. This step including the lower profile collar then gave more flybar travel totaling 22-24 degrees depending on how you looked at the flybar and pitch gauge. But still it was lop-sided +17 and -5.




6. So, I finally got smart and shortened the ball links controlling the the blade drips by 2mm. This allow me to get more of a balanced collective travel of +14 and -10.



The negative pitch problem is now solved. For those of you who don't want to do all of the modifications, just add the CNC head and leaving on the stock collar. This should give you enough collective travel (total 18 degress) to do 3D (especially with the brushless motor) just by shortening the ball links by 2mm to balance that travel to a final result of +9 and -9. But I wanted to go all out to create the monster this heli has the potential to be.

I hope this post helps guys.

Predator, Raptor 30, TRex CCPM 450TH, 3D Pro 400F
05-20-2004 Over year old.
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e-Century Hummingbird - Swift > CP: more negative collective problem solved
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