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Mar 16, 2006, 12:44 PM
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Help!

Need 12mm CCPM swash for coaxial biild


I am looking for a CCPM swashplate that uses a 12 mm shaft. I am thinking of trying to build a coaxial heli, but I really don't want to machine my on swash.
I would rather leave that to someone like Copperclad.
Thanks.
Jim
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Mar 17, 2006, 12:13 AM
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Well, I thought maybe the Raptor 60/90 was a 12mm, I can also design around another size. 10mm maybe?
Mar 17, 2006, 06:34 AM
Coaxially Fixated
copperclad's Avatar
hi Jim

an R-90 swash is 12mm i believe , the main bearings are 12mm X 24mm X 6mm , it is setup as a 90 degree swash not 120 degree

the JR Sylphide 90 has a 12mm shaft and eccpm swash ( might be an upgrade ) but i think price and availability will rule it out

Vario makes a 12mm eccpm swash
http://www.variocanada.com/index.php...3f83155d55c250


building up a design around an off the shelf swash is a great way to go , machining a swash is a great project in itself but adds a ton of work to a build , 12mm is pretty big as far as stock swashs go , i think even the big gassers like the bergen intrepid and the century predator are only running 10mm main shafting ( my R-30 has a 10mm main shaft )
an idea that will really help , is to look at the setup they use on a BCX with the bearing cups , the bearing that supports the inner shaft is bigger around than the inside diameter of the outer shaft , the bearing cup supports it out past the end of the outer shaft and this lets the outside diameter of the inner shaft and the inside diameter of the outer shaft be very close to the same size , this really helps to keep the outer shaft diameter down to a reasonable size , i have been thinking of doing another build with these BCX style bearing cups and an off the shelf swash , always glad to bat ideas around and am happy to share anything i have as far as designs go

for a while there was some talk about useing needle bearings as they have a very thin profile , but my brother pointed out they can't handle any kind of thrust load , when i started my CP coaxial build i started with the swash and designed around it , i had a piece of 22mm OD tubing and used the boca bearing database to see what size bearing - inner shaft i could run and it worked out to the largest inner shaft i could do would be about 10mm , i was setting it up with the bearing inside the outer tube , because i didn't know any better at that point and ended up with a 10mm inner and a 22mm outer shaft
dana
Last edited by copperclad; Mar 17, 2006 at 09:22 AM.
Mar 17, 2006, 10:14 AM
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Thanks Dana, I was thinking about using the same setup as a Blade CP with the bearing cup you mentioned. With a 12mm setup, it seems like the wall thicknesses would be about right for 520mm blades. With a 10mm setup I was thinking about using the follwing:
4130 chrome molly from Aircraft Spruce
PN 03-0200 for the outer shaft would be 7/16OD turned down to .393 (10mm), with a .308 ID, and .042 wall.
PN 03-00510 for the inner shaft would then be 1/4OD, .120ID and .065 wall.
I think this would give me about a .029 gap between outer and inner shafts.
If I use about 19% of the rotor diameter for distance between the blades, plus the length of the lower head, that gives me about 8" of shafts above the upper frame bearing.

So, questions with that setup ... Do you think 4130 is strong and stiff enough with .042, and .065 walls, and an 8" length? And is this setup is strong/stiff enough for 520mm blades (Eco 8) sized?
Mar 17, 2006, 10:19 AM
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If you have any other suggestions, I would really like to hear them. This forum is great for bouncing ideas back and forth.
By the way Revolution makes a 10mm CCPM swash for the Raptor 30/50. I think the P/N RVO1200. It's available from Horizon.
Mar 17, 2006, 12:30 PM
Coaxially Fixated
copperclad's Avatar
hi Jim

i ended up running 7/8" ( 22mm ) 6061-T6 outer shaft and a 3/8 inner of 4130 moly, the inner is .049 wall thickness and from the top of the frame the inner shaft is 10" and 14.5" overall , i see the two shafts as being a unit so the inner is really only under a torque load because it is supported by the outer shaft

another option would be to run a stock R-60~90 swash and add a half ring to the back three horns this would let you reapply the balls at 120 or 140 degrees , i saw some T-rex conversions like this where a thin slice of alloy tube was cut and then about 180 degrees of the ring was attached the the three rear horns ( or the two sides and rear horn ) then they redrilled for the balls at 120 dgrees

i might be tempted to grind out the spherical bearing to 7/16 or replace it with a 7/16 unit and just run with the 7/16 shaft

i am an old school , seat of the pants kind of builder ( read that > no machanical engineering degree< ) so i tend to fall on the overkill side of things

so i might be tempted to go with a 12mm swash and again swap out or grind out the spherical bearing to 1/2" and run 1/2" and 3/8" seamless thinwall moly tubing

and i am pretty sure you have seen this link on my .30 CP

https://www.rcgroups.com/forums/showthread.php?t=442956

as you know i am not too shy about sharing what i've tried and there are a full set of pictures and discussion on how the design evolved , i learned a ton of things through the interaction of posting the build here , and had a riot building it , i find bouncing things back and forth is a great way to iron out ideas and about as good as the hobby gets , dana


here is the supply i ordered my tubing from


6061-T6
http://www.onlinemetals.com/merchant...ep=2&sortby=od
4130 moly
http://www.onlinemetals.com/merchant.cfm?step=2&id=250
Last edited by copperclad; Mar 17, 2006 at 12:48 PM.
Mar 18, 2006, 07:50 PM
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Thread OP

I am going to try a 10mm


Friend brought over a swash from a 90 Raptor SE. I guess he had a "mishap" a few days ago, but I got to hold it. Yes it is 12mm, but boy is that thing is heavy That, along with the extra weight for a 12mm shaft, with the appropriately sized inner shaft, we are talking about a lot of weight. On top of which I would have to rework it for CCPM like Dana mentioned.
OK lets regroup. LHS had a 10mm swash from Revolution that I mentioned a few posts ago, so I bought it. It has pre-drilled holes for either a 90 or 120 setup. It also has predrilled holes for the ARPfor both setups. And it has a much lower profile than a lot of other swahes I have seen.
So, 10mm it is. I will get the tubes on order on Monday. Just have to decide which ones to get!! Dana, I agree that the outer shaft carries most of the bending loads, and the inner is mostly just torsional, so the outer shaft has to be the stongest one.
I also have the same verticle/horizontal rotary table on order that Dana mentioned in his 30 sized coaxial build thread. I might not need it for this project, but it is an accessory that I have always wanted.
Mar 18, 2006, 09:04 PM
Coaxially Fixated
copperclad's Avatar
hi Jim
yes the R-90 swash is big , it would be nice to find a 10mm in plastic , the inner shaft is well supported but there is the interface between the top bearing and where the inner shaft connects to the top blade hub , all the stress is focused at this point and again at the section between the drive gear and the lower bearing , i groused around on this and batted ideas back and forth with Dan and settled for red locktite and it has been working fine , the outer shaft ends up being overkill almost no-mater what you use , it is just the problem of connecting the lower blade hub to the shaft , on my shogun FP coaxial i just ran two screws though the hub and though the shaft and had then threaded into a liner i slid up into the outer shaft , it has worked out fine too , and was a lot simpler then the system i used on my .30

the drive train ~( swash , shafting , gear hubs ) are the hardest part , once you get past the drive train the frame is cake , and every thing goes a lot quicker

i don't remember if i talked about the grizzly index in the .30 thread but i had to make a mounting base for it to mount it to my lathe , it is listed as being horizontal or vertical but then come with just a single horizontal mounting tab , other than that it's a great little index , and made cutting the swash horns easy

what kind of setup are you planning , FP or CP , will it have a stabilizer bar , double or single motor , do you have a way to post pictures of drawings or sketches , chinlin posted a thread on coaxial designs and he and roffy and i have been batting around ideas there , it's got me leaning towards a CP , single motor , dual swash , non stabilizer design probably with three bladed heads , still just an idea , no real design yet , just bits and pieces

dana
Mar 20, 2006, 10:34 PM
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Thread OP
Long week-end, I was drilling a hole on the mill/drill last night and I stripped the threads on one of the 5/8 clamp bolts on the back of the machine I had to drill out the head of the bolt to get it out Finally got it.
I was also thinking about how I could easily attach the upper shaft to the upper rotor head with a three blade design. If it wasn't too heavy one of these shaft lock sleeves might work. A screw through the shaft like Dana mentioned also might work. Not sure about red locktite, I might want to get it apart when I crash
Dana, I am definitely going CP, I still havn't decided on an upper swash or not. Your last post in chinlin's rotor dynamics thread looks very intriguing though. That would give me an excuse to use my new rotary table for my hubs I am also not looking for a 3D machine. Can't remember which thread, but there was an rc coax that used a push rod comming up through the top of the upper rotor head to produce upper collective. That might be easier, except I can't figure out where that acutation would be coming from. It would almost have to come from below the lower roter shaft.
So I still have lots of unanswered questions.
Yes Dana, I have also been looking at those three bladed designs with no flybar or stabilizer. It would sure make life easier as far as the build is concerned.
Mar 20, 2006, 10:41 PM
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Thread OP
Oh, I almost forgot, I wanted to ask a question about milling machine coordinates. I think it's called the Cartesian coordinant system. If the table is centered in both X and Y, that point is call the origin, or zero point. From that point, if the TABLE moves away from the operator, is that + or - Y. And if the TABLE moves to the right from the operator is that + or - X?
Thanks
Mar 22, 2006, 11:04 AM
Coaxially Fixated
copperclad's Avatar
hi Jim
my bad , i thought i had been watching this thread and i missed your posts

with coordinants i am not sure there is a standard , there are a mess of systems , absolute and relative , from all over the world , i have worked on a EDM that ran off a PDP-8 and paper tape , 70's vintage , so i bet there are different ways to go , i have a CAM plasma cutter i built and went home position in the lower left corner , so X increases as it moves right and Y increases as it moves up , with the way i do things , i can almost guarantee that it goes against industry standards

i have been working on a series of coaxials that started with a simple copy of the XRB hirobo and then i went to the .30 i just finnished , next i want to try a hybrid clone of a gyrodyne and hummingbird "A" i have been thinking about , i would like to go single motor too ,
Mar 22, 2006, 11:15 AM
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Thread OP
That sounds cool. Can't wait. One more question about your 30 (like this will be the last) Since your upper rotor is collective, how did you account for antirotation of the upper head, since the lower head is spinning in the opposite direction?
Thanks again,
Jim

PS My rotary table is supposed to be here today
Mar 22, 2006, 11:21 AM
Coaxially Fixated
copperclad's Avatar
almost forgot

most of the design work is figuring out how to build it so it is easy to work on , a good example of this is the first method i used to attach the lower head to my .30 , i thought there would be no need to take it off and then locktited it on in the wrong place , then spent three days trying to get it back off without destroying the head , heat works if you don't mind having to get it red hot , and forget about solvents , , the work around i did , in hind sight i should have done from the beginning , like i say , " test first , lesson later "

the bottom end of the upper head could just be split to act as a collet , the bergen heli's use a system like that , drill and tap for two screws and then split the hub at the bottom and tightening the two screws draws the bottom together like a collet
Mar 22, 2006, 11:30 AM
Coaxially Fixated
copperclad's Avatar
hi Jim
here are a few pictures , i don't know what you are asking about anti rotation , the second picture shows the slot the stabilizer rides in , there is a control rod the moves the pivot for the stabilizer up and down inside the upper head , the servo for this is at the bottom of the airframe , under the main shafts , dana
Mar 22, 2006, 11:49 AM
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Thread OP
Either I am not understanding, or I didn't explain my question real well - I have been known to do both
So, rephrase - it seems like every design I come up with, I can't figure out the AR for the upper swash. The bottom swash is no problem, just decide (READ ask the guys on the forum) where the AR needs to be, and attach it to the frame. The upper swash though, seems like it is out there in no-mans land and is free to spin along with the upper head. Maybe there is enough support from the control arms coming from the lower swash?


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