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Aug 31, 2009, 08:51 PM
Registered User
Discussion

Blade MSR problem, does yours do this?


First off I have to say what a cool little heli the MSR is!

Out of the box mine flies great but there is one problem I have noticed. Tail spins are not right, it acts as if the heli is out of balance or cyclic (swash plate movement) is being applied. Same is true with forward rudder movements, if you turn left (rudder) the helicopter will have forward cyclic and if you turn right (rudder) it will have the opposite or reverse cyclic meaning during aggressive forward left turns the heli will actually nose down just a little and boogie and during forward right the heli will nose up and try to pull up just a hair. Aileron and Elevator are fine by themselves it is only rudder that then seems to be affecting Elevator. For someone fairly new to flying this would probably go completley unnoticed.

So far I have tried binding a DX7, DX6i and a RTF controller just to see if it was a transmitter issue but all three behave the same.

I have only had the MSR for about an hour so I have not dug into it and see if I can find the problem yet but something is going on. Does anyone else notice this? If you have an MSR can you do clean tail spins without a little wobble?
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Aug 31, 2009, 08:55 PM
Registered User
Eyefly's Avatar
I noticed the same thing. Here was my question on another thread;
https://www.rcgroups.com/forums/show....php?t=1103941

The swash moves on moving the rudder stick. Try it.
Aug 31, 2009, 08:59 PM
KD9GTO
Mine does too, and severe toilet bowl as well.
Aug 31, 2009, 09:05 PM
Registered User
Hey Eyefly,

Good, it not just me.

Yep, after digging into it I can clearly see that if you apply rudder the elevator servo is moving. If you move rudder left the elevator servo moves one way and if you move rudder right the elevator moves the other way. This would explain the problem I am having and why the heli behaves differently when doing forward left circles compared to forward circles and not being able to spin without a little wobble.

Just to conirm I am not crazy I tried hovering and applied just a little left rudder. The result is the heli moves forward in a small circle and if you if try hovering and give it right rudder the heli moves backwards in a small circle. This would also explain why the tail spins are not clean too.
Aug 31, 2009, 10:29 PM
Team SCHC
zguy's Avatar
Quote:
Originally Posted by stersman
Hey Eyefly,

Good, it not just me.

Yep, after digging into it I can clearly see that if you apply rudder the elevator servo is moving. If you move rudder left the elevator servo moves one way and if you move rudder right the elevator moves the other way. This would explain the problem I am having and why the heli behaves differently when doing forward left circles compared to forward circles and not being able to spin without a little wobble.

Just to conirm I am not crazy I tried hovering and applied just a little left rudder. The result is the heli moves forward in a small circle and if you if try hovering and give it right rudder the heli moves backwards in a small circle. This would also explain why the tail spins are not clean too.
Excellent find!

Now how do we "un-mix" it?
Aug 31, 2009, 10:35 PM
Registered User
First of all I don't have an Msr but from the description in the first post I think that they may have implemeted this rudder to cyclic mix to make the heli more neutral when turning stationary in hover.

I will try to explain it:
Assuming that the main to tail rotor angle is 90 the heli will hover sligthly inclined to the right side (assuming cw rotor turning) to avoid sideward movement resulting in the tail rotor having a vertical thrust component that pushes the tail up (blows air down). If you turn right the tail thrust increases and the tail will raise resulting in a slight forward movement. When turning left the tail thrust decreases and so does the vertical thrust component from the tail resulting in a falling tail and a tendency of the heli to move backwards. The described elevator/rudder mix would counteract these effects that are typical for low headspeed/hight torque fp helis.

Usually the pilot would take care and compensate unconsciously for the slight forth/back movement. It seems the build in mix overcompensates.

Cheers,
Ruben
Last edited by spainman; Aug 31, 2009 at 10:42 PM.
Aug 31, 2009, 11:50 PM
Registered User
sky guy's Avatar
It seems you could use your DX6i to mix the controls slightly in the opposite direction until you get the characteristics you want.
Sep 01, 2009, 12:17 AM
Registered User
It could be that this was implemeted. To add to the confusion the MSR has a clockwise rotating main rotor and if you look at it closely the main rotor shaft has an offset of a couple of degrees. The first time I saw the rotors spinning it caught my eye to see the rotor disc at an angle. This is obviously a built in design to help the inherent roll that single rotor helis have. These helis can hover hand free so the must have done something right. The excellent hovering might come at the cost of slight awkward rudder control.
Sep 01, 2009, 12:21 AM
Registered User
On the DX6i you can use Mix 1 and set rudd to mix with Elev. I found that 45% on D and 60% on U completely unmixed the monkey motion. You can do the same with the DX7 but there percentage will vary.

Now I can give it rudder without elevaotor being added. I do not yet know if it helps? It might just take time to figure out the best mix.
Sep 01, 2009, 12:36 AM
Rocket Programmer
jasmine2501's Avatar
Yeah I noticed that too... the main shaft is tilted a bit to the right. We got three of them out of the box to confirm that this was by design - I was pretty surprised to see it. Also, on mine, the tail rotor was not angled straight up and down... and the boom is somewhat loose and you can rotate it. I am not sure which way it's supposed to be - if it is aligned with the main shaft, or if it's supposed to be tilted so it's straight with the body.

As I keep looking at this thing, I'm noticing a few little design tweaks like that, and it's very interesting to see what they've done with it. I can't believe it flies like it does - it's not what I expected. Flies a lot like a coaxial - can't wait to get in a bigger space and really open it up though and see how fast it is.
Sep 01, 2009, 01:26 AM
Advanced Heli Collector
9sec240's Avatar
Jasmine, both mine have the tail motor pointing slightly down on the blade side. I would have to say they are designed that way.
Sep 01, 2009, 07:30 AM
Registered User
Eyefly's Avatar
I will try the mix tonight and see if it makes a difference.
Sep 01, 2009, 01:37 PM
Fly Runaway Fans
'So easy a caveman can do it' might not have been the best compromise. Interesting effort though. Rather like a halfbaked computer stabilization system. They should have at least put a pot on that RUD/AIL mixer so you could turn it down if it bothered you.
Sep 01, 2009, 03:18 PM
RC Helis: My Healthy Obsession
Quote:
Originally Posted by stersman
On the DX6i you can use Mix 1 and set rudd to mix with Elev. I found that 45% on D and 60% on U completely unmixed the monkey motion. You can do the same with the DX7 but there percentage will vary.

Now I can give it rudder without elevaotor being added. I do not yet know if it helps? It might just take time to figure out the best mix.
Did the same with my 9303. It flies just fine that way. It also turns left smoother without flying the elevator stick so much.
Sep 01, 2009, 04:39 PM
Axes & Blades-Cutlery & Helis
Quote:
Originally Posted by dkfuji
Did the same with my 9303. It flies just fine that way. It also turns left smoother without flying the elevator stick so much.
So essentially, it now flies like a real heli and not like a COAX? I'm glad I read this thread good stuff


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