Chronos build questions?

[Rob43]

Good question. I don't think it's ever been included in any of the Compass kit instructions, but I could be wrong. I've never seen it detailed in any of my kits.

[crickr1]

OK guys, heres my next question
Still waiting on my tail servo so I havent been able to finish yet, so going over links,swash, basic gyro set up etc.
Noticed the links from servos to swash seem to be on poor angle. Has anyone moved ball position to 13mm instead of 15mm?
Looks as this would clean up angle .
Since the Chronos swash is larger then 7hv, could this be oversight in manual?
Running Savox 1257tg servos with seacraft 15mm arms.
Also, looking from the back, the ELE linkage is not in line with main shaft. Looks like I should turn the ball to other side of arm and maybe shim the servo away from frame to compensate?
Thanks

[Ah Clem]

"Noticed the links from servos to swash seem to be on poor angle. Has anyone moved ball position to 13mm instead of 15mm?"

I just measured mine-the balls on the cyclic servo arms are 16mm out from the center (where the holes in the arms were). If they were at 15mm, the servo arm balls would be directly underneath the swashplate balls. The angle in your photograph actually looks very good, as you will get slightly less differential throw (as the rotory motion of the servo is translated into the linear motion of the pushrod) with the balls in the slightly over-center position with the arms centered.

"Also, looking from the back, the ELE linkage is not in line with main shaft. Looks like I should turn the ball to other side of arm and maybe shim the servo away from frame to compensate?"

The ball on the elevator servo arm ball is mounted to the underside of the arm on my ship. When viewed from the back, the servo arm ball is directly under the swashplate ball.

I would shim the servo, the ball, move the ball to the other side of the arm, etc. as necessary, to get good alignment.

I am using JR SLS01 cyclic servos with Dubro Heavy Duty Servo Arms. Different servos have different deck heights, and different servo arms have different heights as well. I did have to shave the very tip off of the bottom of the ball mounting screw where it exits the nut on the servo arm, so that it did not interfere with the aluminum mount. I also had to relieve the aluminum mount slightly where the QRS connector protrudes from the two front cyclic servos, as it interfered slightly (the QRS connector is slightly wider than the standard servo wire grommet).

This is how my servos are mounted-my apologies that the arms/balls are not shown in this photograph:

[crickr1]

All the servo links are closer to centerline of mainshaft at servo location, and wider at swash. This being at "0" center stick,
Here is better pic showing linkage angle at 15mm.

Plan on moving ELE servo and adjusting to center linkage from back view, currently,servo arm centered to mainshaft as opposed to the linkage. Will shim servo accordingly.

[Rob43]

Having a perfect geometric appearance isn't as important as being in range for the control algorithms for the FBL unit. I had this same thing when I last rebuilt the 7HV. Could get perfect alignment but out of range, or in range, but imperfect alignment. Not sure why this is the case. I doubt it matters unless you plan to fly F3C.

[cyclo]

crickr1, correct me if I am wrong but looking at your pics it appears you are using the outer (17mm) holes on those Secraft v1 servo arms. I have 17mm Secraft v1 servo arms on one of my 7HVs.

If I am not mistaken, for Chronos it is suggested to use 15mm (inner holes on the Secraft v1) which means the one closer to the shaft on those Secraft v1 servo arms. That should "improve" the geometry.

EDIT: Below is a pic of JadAl_87's Chronos... It is not too clear but he appears to be using the inner hole on the servo arms:

[crickr1]

Originally Posted by cyclo

crickr1, correct me if I am wrong but looking at your pics it appears you are using the outer (17mm) holes on those Secraft v1 servo arms. I have 17mm Secraft v1 servo arms on one of my 7HVs.

If I am not mistaken, for Chronos it is suggested to use 15mm (inner holes on the Secraft v1) which means the one closer to the shaft on those Secraft v1 servo arms. That should "improve" the geometry.

EDIT: Below is a pic of JadAl_87's Chronos... It is not too clear but he appears to be using the inner hole on the servo arms:

"I am using 15mm servo arms from seacraft, the smaller hole is at 13mm"

That picture looks much better, I had to relocate ball, and shim my ELE servo to center with main shaft from rear view. Starting to wonder if these servos are just a bad fit for this heli?

[crickr1]

Originally Posted by Rob43

Having a perfect geometric appearance isn't as important as being in range for the control algorithms for the FBL unit. I had this same thing when I last rebuilt the 7HV. Could get perfect alignment but out of range, or in range, but imperfect alignment. Not sure why this is the case. I doubt it matters unless you plan to fly F3C.

Since I fly MSH Brain FBL it does not have a required "Range" like some other units. I know they all have an optimum sweet spot, but every heli has its own geometry as well. Not being as familiar with Compass as other helis, I am use to a more symmetrical geometry appearance.If I remember correctly, the older 6hv you were able to shim servos more.

[Sebastian Zajonz]

Hello,

please use 15mm servoarms and no others. The head geometry of the Chronos is optimised for 15mm and you will loose a lot of performance using 13, 14 or 16mm. The reason is, there is a build in counter error to fix the error of the transmission from servo to swashplate (different length of arms cause angle error). So the links of the servos should never run perfectly parallel to the main shaft (at 0° pitch), but in this special case in an shape looks a bit like a trapezium. If you use the right servoarm length you will get a perfect flying machine.

The reason why the chronos is flying just so awesome is the geometry! I spend so much time into it and its really worth. I know no other helicopter flying with so less interactions during maneuvers. Everything you do with the Chronos is more smooth and still fast, precise and more on the spot, as with any other Heli I've flown before.

Greetings
Sebastian

[crickr1]

Originally Posted by Sebastian Zajonz

Hello,

please use 15mm servoarms and no others. The head geometry of the Chronos is optimised for 15mm and you will loose a lot of performance using 13, 14 or 16mm. The reason is, there is a build in counter error to fix the error of the transmission from servo to swashplate (different length of arms cause angle error). So the links of the servos should never run perfectly parallel to the main shaft (at 0° pitch), but in this special case in an shape looks a bit like a trapezium. If you use the right servoarm length you will get a perfect flying machine.

The reason why the chronos is flying just so awesome is the geometry! I spend so much time into it and its really worth. I know no other helicopter flying with so less interactions during maneuvers. Everything you do with the Chronos is more smooth and still fast, precise and more on the spot, as with any other Heli I've flown before.

Greetings
Sebastian

Thank you Sebastian,

I did notice that at full + and full - that the servo links are then // to main shaft as opposed to others // at "0" and offset at +, - . This would explain the faster cyclic response.

Thank you,

Looking forward to my maiden, Hopefully Sun if weather breaks soon. In for a nasty few days ahead here in N East.

[Rob43]

Excellent discussion.

Do those Secraft arms have a precisely 15mm hole position?

What others do? I have Mikado arms currently.

[crickr1]

Originally Posted by Rob43

Excellent discussion.

Do those Secraft arms have a precisely 15mm hole position?

What others do? I have Mikado arms currently.

Yes , the secraft model:
http://www.espritmodel.com/aluminum-...futaba-m2.aspx
Are 15mm and 12mm., They also have a 17mm/14mm as well as many other combinations. I have been using these on many helis and work fantastic! In crash they designed to bend, to save servo gears, Never stripped a gear in crash with these
Also you get the strength of aluminum so no give in control surface. And at $3.50 a piece, not priced too bad at all.

[cyclo]

crickr1 I was wondering if you had maiden your Chronos.

[crickr1]

Originally Posted by cyclo

crickr1 I was wondering if you had maiden your Chronos.

Everything has been on hold, between crappy weather every weekend and personal matters havnt had time. All I need to do is final FBL set up, blade pitch, etc. Now our field has no access due to 12" of mud

[simplechamp]

I thought I would add my question here rather than start my own thread.

When tightening down the feathering shaft bolts the blade grips start to feel very notchy when I rotate them. Is this what is meant when you guys are saying the head is very tight out of the box? I read this and took it to meant there was some resistance, but I was expecting it to be smooth not notchy and gritty feeling.

[Ah Clem]

Make sure that the thrust bearings are properly lubricated (with grease).

Some notchiness can be expected upon assembly of a new machine, or when replacing dampers. This will go away after five flights or so.

If it is extremely notchy then I would disassemble and re-assemble it.

[simplechamp]

Thanks for replying so quickly.

I pulled the head apart and everything is definitely well lubed with silicone grease. All the parts seem to be in their correct places and orientation. I tried pulling on the blade grips and rotating like someone else mentioned and it does reduce the notchy feeling. Must just need to be broken in.

[crickr1]

Originally Posted by simplechamp

Thanks for replying so quickly.

I pulled the head apart and everything is definitely well lubed with silicone grease. All the parts seem to be in their correct places and orientation. I tried pulling on the blade grips and rotating like someone else mentioned and it does reduce the notchy feeling. Must just need to be broken in.

MIne was same way, If you pull on blade grips as you rotate them, you should feel them move more freely. This represents the forces in flight. Also check your dampening.I have my dampening block a little over 1mm gap between headblock and adjusting stopper. Since dampers new, very tight, you can always tighten them later as your flying style may prefer or. after couple flights they should loosen up a bit and even require to be tightened.
I like the unique design of dampening system, lot of thought went into that

[simplechamp]

So I have been going forward with my build, but I keep going back to the head. I'm sorry for sounding like a broken record, but is it really supposed to be that tight?

I've had it apart and back together again several times, and I'm certain everything is in it's proper place and assembled correctly. You are supposed to tighten the feathering shaft bolts all the way down right, so the washer is pressing right up against the end of the feathering shaft? When I have them all the way tightened down there is about a 1.5mm gap between the blade grip and hub where you can see the black spacer.

I adjusted the head button to the recommended 1-1.5mm gap and it made things even tighter. I know I am reading that this is normal but I'm having a very hard time getting past it. I wish I could feel what someone else Chronos head was like, it's hard to judge what pretty tight is.

[sewerfly]

Mine too was tight until after about 8 flights or so it has to be broken in with the 700 hundred size blades swinging at good head speed it will pull on the grips I think you'll be fine