Even more cyclic with CGY750?

[Bob Heybrock]

I seemed to be perfectly happy with the cyclic performance of my N5c after lowering the head until I recently acquired and flew my E5, suddenly everything else is slug slow! 

With the goal of increasing the cyclic even more, changing the geometry was recommended because otherwise the cyclic setting on the CGY750 has to be cranked up to close to 90% so I obtained a set of 310-153 blade grip arms, which come on the E7SE head and therefore can be fitted on my N5c (non TT edition.)

I already have the long (taller) pivot balls on the inner swash so there is no doubt that this is a route to go and will increase the cyclic and however it will increase the collective travel too which brings me to the main question of this post.

When originally setting up the CGY the collective travel was excessive and in order to reduce it the radius of the servo horns was reduced to about 10.5mm, which did have the undesirable effect of some, albeit minor, binding of the mechanisms caused by that radius working with a 14.5-15mm radius at the swash bellcrank.

So has anybody besides me thought about instead of changing the blade grip arms to reduce that radius go back to an already unfavorable configuration at the servo horns and along with increasing the travel also ridding those mechanisms of the binding problem?

I started out with a piece of paper, a sharp pencil, a protractor, a T-square and the idea I was going to have to restudy my college calculus courses in an effort to calculate the amount of change I might expect between these to possible routes but decided to post this instead, lazy I know but whatever it takes!

My buddy is in the process of changing out the blade grip arms and I await the results he comes up with but in the meantime I was hoping to find someone out there who has already messed around with this.

Thanks!

[Rodney Kirstine]

Which firmware are you running on the CGY-750?

[Bob Heybrock]

Rodney, 1.4 just recently.

[p johnston]

I use 1.mm washer under the long ball studs on the inner swashplate. Use caution not to strip the threads out. I use the solid Futaba wheels drilled out at 10mm. Gave me the feel I was looking for.
Hope this helps

[Rodney Kirstine]

Bob,

Check out this post from Matt that's in the "tips and tricks" section:

http://synergyrchelicopters.com/forum/index.php?topic=19.0

[Bob Heybrock]

As stated in the initial post I already have done what Matt is talking about with the longer pivot balls on the inner swash for the pitch link rods.

[Rodney Kirstine]

Sorry, I should have re-read your first post before I posted that link.

[Chris "CSpaced" Mulcahy]

With my belt drive N5c, I did the same thing Bob had done with the swash and servo horn spacing. Rolls and flips were okay, just not lightning fast, which is how I've grown to like it

So, I cranked up my CGY750 out of its sweet spot to almost 90%, which gave me about 12 degrees of cyclic, where as before I barely had 8 degrees (this is with 12 degrees collective pitch with the CGY in the sweet spot of between 60% - 70%). I flew the heli this way for a couple of flights, but of course the CGY was quite wobbly with these settings. The cyclic response was awesome though, and now that I've had a taste I want to try and get both the cyclic and the collective at about 12 degrees pitch with the CGY around 60% - 70%.

So, now I'm experimenting with different blade grip arms, swash ball lengths, and servo horn configurations to see which works best (I'm a hands on guy!). If anyone else has a similar set up and has figured this out already, I'd love to know!

[p johnston]

Quote Bob3506 from original post-
"I already have the long (taller) pivot balls on the inner swash so there is no doubt that this is a route to go and will increase the cyclic and however it will increase the collective travel too which brings me to the main question of this post."

This is false. It will only change cyclic values.

Did you put a spacer under the ball stud on the inner swash? 1mm makes a big difference.
I also put short ball studs on the outer swash.  I don't have a pitch gauge so I can't give degrees of pitch.  I go off of feel and gyro values.

The only way you can change cyclic values WITHOUT changing collective values is by changing the working radius of the  inner and outer rings of the swash plate. IE the length of the ball studs. Changing servo wheel distance, blade grip arms(perpendicular distance from grip) , and bell crank ratios will change both cyclic AND collective values.

[Chris "CSpaced" Mulcahy]

The only way you can change cyclic values WITHOUT changing collective values is by changing the working radius of the  inner and outer rings of the swash plate. IE the length of the ball studs. Changing servo wheel distance, blade grip arms(perpendicular distance from grip) , and bell crank ratios will change both cyclic AND collective values.

That's exactly what I found yesterday. I ended up changing out the three lower swash balls to the shorter ones, and the longer swash balls on the blade grip pushrods. This gives me about 12.5 degrees collective with my CGY range set to 50%, and about 10.5 degrees cyclic with my CGY range set to 70%. I'm going to shim the longer blade grip swash balls 1mm, and then try a few flights.

[Chris "CSpaced" Mulcahy]

Just to follow up, after all the tweaking and testing I ended up with everything back to stock except for the outer swash balls being changed to the shorter balls, and long swash balls on the blade grip pitch link inner swash. This gave me all of the throw I wanted on cyclic without affecting the collective pitch. End results? One happy N5c!

[Bob Heybrock]

Quote Bob3506 from original post-
"I already have the long (taller) pivot balls on the inner swash so there is no doubt that this is a route to go and will increase the cyclic and however it will increase the collective travel too which brings me to the main question of this post."

This is false. It will only change cyclic values.

I may have written my initial post poorly & separated the same thought with a new paragraph. What I was referring to in the quoted paragraph was that the shorter radius blade grip arms would change both cyclic & collective and that is why I was considering correcting the slight bind in the servo arm to bell crank configuration. But as posted by you and others and discovered by Chris I now understand fully the effect (and benefits) of changing only the swash ball lengths. Next rainy weekend day I will be changing the lower swash balls to the shorter ones and will also follow your suggestion of the 1mm washer behind a couple of new tall ball links on the inner swash.

Thanks to all for the help!

Bob

[Chris "CSpaced" Mulcahy]

I forgot to mention that with the short outer swash balls and the long inner swash balls, adding the 1mm shim on the inner swash seemed to be a bit much for the CGY, it was much happier once I pulled the shim back out. Your results may vary