Does this look right

[Shink]

Hi guys.

My first ever rc helicopter arrived today and I am concerned that it is faulty but can't tell because I have never seen one before!

I noticed on opening it that the central axis of the main frame appears to be out of line.

The main gear is quite a few degrees out of horizontal with the skids.


Please see these links for images.



https://www.dropbox.com/s/9x5930k4es...22.51.jpg?dl=0


https://www.dropbox.com/s/lj2wd5y115...33.30.jpg?dl=0


https://www.dropbox.com/s/vcgg6xozsd...21.41.jpg?dl=0

I was able to get what I think is a pretty decent trim after much fiddle with the control arms which attach to the swash plate.

But I still don't think it is as good as it should be...


Thanks for your thoughts...

[Boggy]

Hi shink welcome to the forum. The msr is well known for its angled main shaft it's perfectly normal.

[Grumpy]

Yeah, it puzzled me when i first got a similar micro heli that the main shaft was tilted to the right. As first I thought that the frame was bent, then I got to thinking about it. I realised that the tiltt must be to create some sideways thrust from the rotor to balance the sideways thrust coming from the tail rotor. So it's deliberatly designed that way. If the shaft was straight then to hover you would have to tilt the whole helicopter to the right, which is in fact exactly what happens with helis that have straight mountred shafts.

If you are adjusting the swash dont try to get it level against the frame of the heli, the swash must be perpendicular to the shaft which will mean it's tilted compared to the frame.

The bias to drift sideways due to tail rotor thust is called 'Translating tendancy' and even full size helis use a tilted main rotor to compensate for it:

Note that this 'real' heli has shaft tilted left because it's rotor spin opposite to most RC helis.

[Grumpy]

PS.. You only find this shaft 'tilt' used on Fixed Pitch helis. Collective Pitch helis are generally designed to be able to fly upside down. If you used a tilted shaft on them it would be tilted the wrong way when inverted. CP helis make do with a straight shaft and they just have to lean a bit to hover.

[Peteski]

Good theory Grumpy, but my co-axial mCX2 is also on the **** in the same direction, although not quite as extreme. Maybe sharing a few common parts with the MSR?

[Grumpy]

It's not my 'theory', its well accepted and well proven helicopter physics. I just thought of it many decades after it was first discovered by someone much smarter than me!

Co-axials dont need the tilt but perhaps, as you say, Blade are saving cost by using the same frame? Got any photos because it does seem odd that a co-ax would have it, are you 100% sure it's not your eyes on the p1ss

[Grumpy]

Yep, looks like your eyes may need leveling (looks straight to me):

[tomatwalden]

Grumpy is correct. The stock mSR has a mast tilt to counteract translating tendency. If a co-ax has the same tilt, it's probably broken! LOL

Similar thread on HF.
My Blade MSR's main Gear/Shaft/Rotor is slanted & off-center - HeliFreak

[Peteski]

Yep, looks like your eyes may need leveling (looks straight to me):
[ATTACH=CONFIG]80756[/ATTACH]

Yep, that's exactly what mine's like, if you look closely the LH swash ball joint is sticking out slightly higher. It's very subtle compared the MSR though. Actually just compared mine to that picture and mine leans over a bit more.

[Grumpy]

Yep, that's exactly what mine's like, if you look closely the LH swash ball joint is sticking out slightly higher. It's very subtle compared the MSR though. Actually just compared mine to that picture and mine leans over a bit more.

We arent talking about the level of the swash, we are talking about the entire rotor mast/shaft being tilted. I think the photo shows quite clearly that the mast/shaft itself on the mCX2 is exactly vertical relative to the frame of the heli, there is no 'tilt'.
You can't really read anything into the swash position because it can move.

[Peteski]

We arent talking about the level of the swash, we are talking about the entire rotor mast/shaft being tilted. I think the photo shows quite clearly that the mast/shaft itself is exactly vertical relative to the frame of the heli. You can't read anything into the swash position because it can move.

Yeah I know, I've spent ages looking at mine for the same reason and it is most definitely tilted relative to the frame. The swash is at 90 deg to the mast in my photo and it's always in the same position at rest. It doesn't move when powered up either.

[Peteski]

There's a pic of the MSR on this website which also shows the leaning mast, but it looks less extreme than yours. Or maybe your swash is out too i.e. leaning even more than the mast.

Blade MSR RTF Mode 1 RTF Électrique - Blade - Mission Modélisme

[Peteski]

It's not my 'theory', its well accepted and well proven helicopter physics.

Yes sorry, I didn't mean it as "your" personal theory. "Theory" was really the wrong word too as it's clearly factual physics.

[Grumpy]

Yeah I know, I've spent ages looking at mine for the same reason and it is most definitely tilted relative to the frame.

If we are talking about your co-axial mCX2 then if the shaft is tilted then I suspect there is something wrong somewhere. I dont have an mCPX myself but the physics say tilt shouldnt be required on a co-axial and the photos online seem to clearly show it to be 'straight'. Do you have photos of your mCX2 that show the tilt?

The MSR helis on the other hand do all have have a 'tilted' main shafts... on that we all agree! I'm sure that the tilt angle is the same on all of them, but it may appear different due to the way the photo is taken.

[Peteski]

Yes, can't understand why it should be offset at all on a co-axial. I did add a picture to my earlier post to show you how it looks. To be honest the landing skids are also far from straight (which makes it look a lot worse than it really is) and the whole thing is pretty flexible. It flies fine though, so not going to spend any time worrying about it. I've got a mCPX arriving shortly, so be interesting to see how straight that is. First one that arrived this week had a completely seized main motor so I'm not convinced on Horizon's QC right now!

I guess on the co-ax helis it really doesn't matter if it's perfectly straight or not as there is no tail rotor to align with the main rotor. So it's just a lump of mass hanging under the main rotors. Mine must fly with the body slightly offset to the main shaft but I don't notice it in flight.