copperclad
Elite Veteran
Location: NY
My Posts This: Topic Forum | Hi gordo
thanks for your interest , i have been working on 45 degree heads for a while now , and became very interested in the mSR after seeing how simple the head design was , and how stable a flier the mSR was
one of the first things i noticed about the mSR head , is that it is a floating flybar design , and reading up on it i was confused because it was being called a bell hiller head , but i could see that it did not have mixing arms like you see on bell hiller
then i saw a post on another site , that explained that the way the links were attached to the flybar hub gave the head some mixing between the swash and the blade grips , and the ratio of this mixing was controlled by not only the position of the links , but also the shape of the flybar hub itself
when looking at the mSR head , and seeing it was floating flybar , i could see that it would be very easy to add a third servo and make it collective pitch , i decided i should mock up a machine based on a larger FP design ( Century HBFP ) and see if the system would work with seperate blade grips , like you see on CP machines
here is a photo of this HBFP machines head and the machine itself , if you have a mSR you can compare it to these photos and see this head is pretty much a dead copy of the mSR head
in the photo of the head , the flybar is not threaded in yet , but you can see the holes for it are drilled
 
doing this confirmed that there were no problems using seperate blade grips in a mSR head , and from what i could see , it should translate to a CP head just fine
so i had a E-sky King II that would work well for a mSR CP conversion and i went about converting it , and came up with this head and machine pictured
also note , i changed the anti rotation sytem for the swashtop and flybar hub
 
but this time when i went to fly it , i found out i had some problems , long story short , the cyclic response was fine but the collective was WAY TOO touchy , and i was pretty discouraged as i was thinking it ment i would have to add mixer arms , and this seemed to defeat the whole purpose of the project
but after sleeping on the problem , it occured to me that the ratio of mixing was dependent on not only the position of the links on the flybar hub , but the shape of the flybar hub as well
what i needed to do was leave the cyclic alone but reduce the collective by half , when i looked at the mixer arms i removed i could see they reduced the throw by 1/2
what i could see by looking at the head was that the blade grips were being directly controlled by the swash hieght position and this ratio was 1 to 1 , and it was easy to see i had to either shorten the servo arms , or lengthen the blade grip pitch arms
i could also see that lengthening the blade grip pitch arms would cut the cyclic in half , and this is something i didn't want , but then it occured to me that if i modified shape of the flybar hub , in order to extend the output links , that i would have half the collective and not effect the cyclic
here are some photos of this extended setup
 
i have been flying this converted King II quite a bit , and it flies very well , but i was a bit down and dirty when i was building it , as it was a proof of concept machine
that is why i took what i learned in it , and started this second one ( 450 mSR CP ) , on the king II , i had used a carbon fiber tube to use for the main shaft , it was strong enough to fly but in a mild crash it would split pretty easy
i also found that using the Kings washout arms for anti rotation arms , limited the collective throw of the head to about 12 degrees overall ( -2 ~ +10 ) , and although this was fine for just flying around , i wanted to have somewhere near 25 degrees overall ( -12 ~ +12 )
so with this 450 build i got some 5mm music wire to use for the main shaft and made sure the AR arms were long enough to give ample collective travel
i feel that the advantage to this setup as it is very smooth and stable , it has very nice FFF handling and there are only about 1/3 the number of parts as in a standard CP head , so it makes a pretty easy conversion to a 45 degree head setup , cheers 
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