Atom technical stuff

[Hati]

EDIT: Here you go Atom Techies - your very own Atom techno thread

Some people (including me) complained about a "wobble" in the main gear and/or tail drive gear that usually causes the drive belt to rub on the main gear. This can manifest in a vertical bobbing of the tail as the belt catches.

The warping is primarily due to overtightening the fixing bolt (part # 80-2518). The correct procedure is to tighten the bolt until the Nylock nut is just seated then apply 1/4 turn more.

If the wobble is already present, you can (in most cases) clear the drive belt by reversing the guide pulleys. Using washers for clearance between the pulleys and mounting block will not be necessary.

[nmanno]

Hi guys, for those of you who want to install the Hitec 5245mg servos into the Atom frame, you'll need to do use a little trick to have a strong hold. See the below link to see how I did it.

https://www.helifreak.com/showthread.php?t=119325

[Ah Clem]

1) If you hear a peculiar buzzing sound coming from your Atom after a dozen flights or so, look at the motor. Several of us have experienced this and landed in a hurry, only to find out that the paper sticker on the side of the motor had come loose and was flapping (at very high speed) against the frame.

Peel it off and the buzz is gone (unless you really like the buzz...).

2) Programming the motor is much easier with the Programming card.

3) Configuring the upper swashplate ring as per the "Atom R" (i.e. removing the spacers from underneath the links going to the washout control) and running the nine tooth pinion is a nice compromise in flight characteristics. For those into sport flying, or not wanting all out 3D, this works out well, with good head speed (about 2700 RPM in idle up) and smooth and positive control response. When one desires to go into all-out 3D, the spacers can be easily re-installed.

4) Phasing on the Knights is adjustable for a reason. I like to do long, slow rolls. After eliminating balance (CG) and CCPM interaction as potential causes of porpoising in rolls, I ended up moving the phasing ring in small increments. Oddly enough, on both the Knight Pro and Knight 3D, the phasing ended up nearly, exactly where the factory would later put the fixed phasing on the Atom.

[TheBum]

Originally Posted by Ah Clem

3) Configuring the upper swashplate ring as per the "Atom R" (i.e. removing the spacers from underneath the links going to the washout control) and running the nine tooth pinion is a nice compromise in flight characteristics. For those into sport flying, or not wanting all out 3D, this works out well, with good head speed (about 2700 RPM in idle up) and smooth and positive control response. When one desires to go into all-out 3D, the spacers can be easily re-installed.

I'd add that you can extend flight times by using the 8T pinion instead of the 9T. I can get upwards of 7 minutes of flight time with a 6S 3000 pack (about 8 minutes with a 3300) when sport flying. The RPMs drop to around 2300, but I've had no issues thus far doing flips, rolls, and loops. You do need to run the ESC wide open (100% flat throttle curve in idle-up) with the 8T pinion though, but the 8T puts a low enough load on the motor that there's no bogging.

[Mercuriell]

Well just about the time we discussed weakness in the base of the Atom rotor head news came of a modded version with thicker base collar - here is the real McCoy - they are ready for dispatch to dealers so you should see them appear in 2-3 weeks time on the shelves

[TheBum]

Originally Posted by Mercuriell

Well just about the time we discussed weakness in the base of the Atom rotor head news came of a modded version with thicker base collar - here is the real McCoy - they are ready for dispatch to dealers so you should see them appear in 2-3 weeks time on the shelves

Only time (and crashes) will tell whether this addresses the real issue. Can you post any shots at other angles?

[MeekaMoMo]

I think they need to put A 3mm bolt in there possable A shear one,also I use a longer bolt so that when it sheaes you can get it out easy, The ATOM is good only COMPASSS now need to go up A gear in there tollerances.

Good Hovering,

MARRTY.

[skunkworx]

Another thing to watch for is the head bolt (at thebas of the head block). After a while, it loosens up and adds even more slop to the head. It gets hidden in conjunction with the delrin dampeners getting loose and makes the head really wobbly on the shaft. Make sure you crank that puppy down and lock-tite it every now and then. Also do the same with the mast locking collar. Had mine fall down on take-off and ruined my day.

[TheBum]

I discovered another possible thing to look out for, especially if you're running an 8T pinion. I haven't confirmed that this was the problem and solution, but it seems probable.

I've been having some problems with right piros where the tail would hesitate, then spin, and then have a big bounce at the end. Left piros were fine. I cranked the gyro gain as high as 50 ATV and was still getting it. I'm pretty sure the G770 gyro is working because on my last flight with the high gain, I heard the tail oscillate in a turn.

I was at a loss to explain it until it hit me: what if the tail rotor blades are stalling? I looked at my tail slider and it was set to deflect all the way to the hub, which was putting my tail blades at about 45 degrees of pitch when applying right rudder. I moved the center point and reduced the throws, which I hope will solve it. I'll let you know.

[Ah Clem]

"if you're running an 8T pinion"

Darn it, Alan-If I want your 'pinion I'll ask for it!

(sorry, stupid pun, but I could not resist).


I have wondered about all the throw/pitch on the tail blades. When the Knight 50 came out, Compass issued a bulletin regarding not exceeding a certain amount of pitch. In this case it was not due to stalling the blades, but due to damage to the front tail drive gear.

45 degrees is quite a bit, from an aerodynamic standpoint. I wonder at what point, at what speed, they actually stall?

[TheBum]

The reason I singled out the 8T is because, with a 9T, it's quite possible that the extra tail rotor RPM would be sufficient to overcome it. I know not a whole lot of pilots fly with an 8T, so this may not be something commonly seen.

[Ah Clem]

Alan,

That makes perfect sense!

[skunkworx]

I'm going to try out the 8t pretty quick here. I want to try all three consecutively and see how much of a difference there is from one to the next. Nothing scientific, just what it feels like to me personally. I just wish the weather would comply. I need to get a night flight system pretty badly.

[trickfrog]

I still fly with the 8T pinion-

I am a novice with about 150 or so flights- I still run only in Normal mode with 92.5% throttle flat line in Gov mode with the stock Pentium ESC- I think I have HS around 2300

I have just started doing hard piros- stick all the way to one side, both CW and CCW.

I haven't noticed any stalling, or funky behavior with the tail- FWIW-

I am using the Zippy 20C 3000's and getting around 8 minutes of flight time-

-J

[TheBum]

My last tip about potentially stalling of the tail blades may be a "never mind". I discovered this weekend that it was left piros giving me problems.

However, my experience does spawn another tip: when setting tail throws, get the slider as close to the arm on the tail case as you possibly can without it making contact. I had probably 2.5-3.0mm of clearance and taking that down to 1mm or so made a tremendous difference. Since a 9T would provide more torque, it may not be as critical as when running an 8T.

[Speed stick 3D]

Just thought I would add in the new manual to this thread! New and Improved

http://compassmodel.com/manuals/Atom...l_partlist.pdf

Thanks,
Devin

Team Compass USA

[akshaw]

https://www.helifreak.com/showpost.p...7&postcount=64

I tried this last night and it works very nicely. This is a great tip. It should have found it's way to this thread when it was posted. Anyway better late than never.

[Jimmy!]

Here's the end-all info for the new headblocks. The hole once bored out above the flybar seesaw is now gone. The once filled-in ream in the very center, top of the head is now drilled through to the spindle shaft cavity. There are now slits cut on both sides of the base of the block to accomodate the new, thicker base.

Something else that's cool, and not seen so well in the pix: The width of the section in which the seesaw goes has been beefed up by 2mm.

For all pix, new is on right, old on left.





Dimension of base (old/new).....................12mm/13.35mm [diameter]
Width of middle section (old/new).............12mm/14mm [flat side to flat side]

[Ah Clem]

Thank you for posting those.

I had not seen the new headblock yet.

[TheBum]

Problem with Atom belt chaffing on main pulley

There are two possible remedies:

1. Flip over the belt. This has worked for several people, including Finless himself.

2. If that doesn't do the trick, check to make sure the idler pulleys are installed with the protruding side on the bottom and, if not, flip them over.