Balancing MKS DS95i

[Manzooka]

Last week I upgraded my tail servo to the MKS DS95i. I had a chance to fly this weekend and really like it, but I noticed a pretty significant drift towards the back right of the heli and it stands to reason that the DS95i (being nearly 3x heavier than the stock servo) is the culprit.

For the moment I have it set up just like the stock servo so that's a lot of extra weight hanging to the right. Any suggestions on getting better COG? The only thing I can think of at the moment is adjusting the servo so it hangs almost directly under the boom and fashioning a bent pushrod to make up for the offset alignment.

I also upgraded the cyclic servos and have a -8 and Ice 50 coming this week. Can't wait for the weekend! (weather pending).

[spykez]

This is what I did:

https://www.helifreak.com/showpost.p...15&postcount=9

Better but not perfect.

[2cants]

I was under the impression that the 3D gyro part of the BeastX is supposed to keep the heli on an even keel - even if CoG is slightly off.

I coudl be wrong. If not - then maybe recheck swash level (look for a little too much Elev)

[Heli.Maniac]

Originally Posted by 2cants

I was under the impression that the 3D gyro part of the BeastX is supposed to keep the heli on an even keel - even if CoG is slightly off.

I coudl be wrong. If not - then maybe recheck swash level (look for a little too much Elev)

Yes you are partially right, but the BeastX has to compensate continuously for that bad CG and sometimes, it is not quick enough to compensate for it. The BeastX performs awesome when everything on the heli is balanced and has the right setup, and a bad CG is making BX task very difficult. Helping the BX by having the right CG and no vibrations will make your and the BX life a lot easier.

[Manzooka]

Originally Posted by spykez

This is what I did. Better but not perfect.

Not a bad idea. I may just give that a try as I have a new motor and ESC to install this week anyway.

Originally Posted by 2cants

...then maybe recheck swash level (look for a little too much Elev)

The swash could potentially be part of the issue but I don't think so. I'm pretty anal about my swash setups and used a leveling tool and some calipers to get it right. That and the drift is most definitely a pull towards the servo, but hey the swash is certainly worth double checking.

I'm thinking of trying spykez idea shown above or making a servo rod that looks something like this so that I can mount the servo directly below the boom.

[FailureToFly]

I think EE just rotated the servo so it sits under the boom and realigned the linkages.

I tried it when I was getting lots of wag (pre DS95i) and it worked fine...but didn't fix the wag so I went back.

I find even after doing a careful swash level I still will get 'some' drift (usually a tiny amount which only shows up when inverted...tail dropping slowly or drifting right/left etc) and just rotate a link etc to sort it.

I'm thinking shortening my front ele link a single turn will likely nail it and it'll still prob be perfect in upright flight.

I might try moving the servo under the boom again too.

[Manzooka]

Better yet, does anyone know of a 450 size servo boom mount that would allow me to mount this servo upright (or upside down) directly below the boom? Such things must exist, but my google search failed me.

[EEngineer]

Exactly FTF, I just re-aligned the servo and linkage orientation for a straight shot to the tail tiller arm......

Manzooka, have you checked, as carefully as you can that the suspected CG issue can be isolated to.....just flat out tail heavy......or tail heavy with some starboard side heavy.....or just starboard side heavy?

Also, is the AR7200BX securely attached to the 450X.....at all of its 4 corners, so to speak....people have mentioned their issues with regards to the mounting tape....and have suggested a 3M tape that worked better for them....

You'll get it figured out.....and the solution might be surprising....

FWIW

[Manzooka]

Hey Engineer,

I'm pretty familiar with setup at this point and I'm confident that the new servo is the issue... at least with regards to the drift. The drift is slight but equal on rear and starboard which would support the possibility that tail servo weight is the issue.

It'll get a chance to test this theory tomorrow after I perform a new setup when I install a new motor, ESC, and go through the entire BeastX setup again.

I'm not too worried either way. The 450X is still flyable as is and I don't really notice the drift unless I'm doing a hands off hover because I'm able to compensate for it during flight at this point.

Still, I'd really like to find a horizontal boom mounted option for a 450 size heli and I'm a bit surprised that I haven't been able to find one.

[Talesin]

Just to state the obvious, but why not apply a step of forward and left trim on the BX Preferences menu? I believe it's step A.

[jdFin]

You could tape some weight to the left-front of the canopy to be sure. Try taping a Krugerrand (34g) to the canopy symmetric to the tail servo and see if you get left-front drift.

[rhodesengr]

manzooka,
Anthing new with this? I just installed all new servos including a DS95i on the tail. I have a pronouced tilt left on lift off and drift left once airborne. I posted in the 450 3D forum since it was a converted 450 3D. I have checked the mechanical and AR7200BX setups and they seem just fine.

Can the added weight of the DS95i really cause this issue?

I have been thinking about using Param A but am reluctant to use that.

[Manzooka]

Originally Posted by rhodesengr

manzooka,
Anthing new with this?

Hey rhodesengr. Is your DS95i mounted to the left of the boom? I only ask because mine is mounted on the right and my drift was a pronounced rear/right.

I seem to have solved this problem, but whether I solved it by improving my swash setup or by adjusting some weight around (or both) I can't say for certain. I installed a new motor and ESC before flying this weekend so I decided to mount my new ESC slightly forward of the stock spot and have my batt wires exiting on the heli's left side instead of the right. I went through the full BeastX setup again as well.

My flights this Saturday felt much improved. The drift is now very slight and only noticeable with hands off hovering.

[rhodesengr]

yes it is a little to the left bascially like the stock one comes setup.

[Coco66]

Originally Posted by rhodesengr

yes it is a little to the left bascially like the stock one comes setup.

The stock is mounted to the right of the boom. Talking about right and left, general understanding is always looking at the heli tail-in.

[B3NNZ]

When I put a 120sr tail on my MCPX I had backwards drift so I put some blu tak in the front of the canopy and that evened it out fine. Try putting weight in the front of the canopy. I think that will do the trick. I am yet to install my DS95s and DS95i so I might have this problem.

[rhodesengr]

Originally Posted by Coco66

The stock is mounted to the right of the boom. Talking about right and left, general understanding is always looking at the heli tail-in.

Yes I had it backwards. The body of the servo hangs to the right and I have a tilt/drigt to the left. However, with everyone suggesting I take a closer look at the tail, I did and found the rotor hub is tweaked. Three bent booms so eventually something in the tail willl get tweaked. Parts on order so hopefully this clears up my tilt. It is counterintuitive that a tail issue manifests like a cyclic issue so its a good lesson.

[EEngineer]

Originally Posted by Coco66

The stock is mounted to the right of the boom. Talking about right and left, general understanding is always looking at the heli tail-in.

Port side versus starboard side......

[Coco66]

Originally Posted by EEngineer

Port side versus starboard side......

Arg! Guess if we'd really have to use those ones... we already use ailreon, elevator and rudder from airplanes, then also port and starboard from boats...

[EEngineer]

Originally Posted by Coco66

Arg! Guess if we'd really have to use those ones... we already use ailreon, elevator and rudder from airplanes, then also port and starboard from boats...

Yes, the use of such naval terms implies looking from tail to nose.....saves typing....