Hi Chaps, thought it would be rude not to post some pics of the old Century Bell 47, mine is electric flys 20+mins. All the best.

Nice

Nice work looks great!! What is your set up for electric that you get 20 min? Sounds really interesting.

Charles

skypup,
I made all the supports with regular tools I don't have a mill or lathe, that would be nice to have and you could really make these parts in a very short time if you knew how to use the equipment. You will need a good drill stand though!
I wanted to keep things simple, the bottom groove was drilled with the two alu sides clamped together, then measurements were taken to have the bearing center end up at the correct height above the crossmember (see original plastic part) . the holes for the bearing insert were drilled and provisions made for the flange of the bearing which is in effect sandwiched between the two alu sides. the whole thing is held together with a screw in the middle, You will have to get a tap for this screw or you can just put a nut on one side like on the original plastic part.
it's actually easier to just make it than to try to descibe it!
fr8dog.

Hi Rotorsport My Electric Bell 47 has X2 3S-4P 11.1volt 8000mah Lipos powering a Hacker C50-16XL motor. The drive is a 20 tooth Joker pinion, the speed controller is a Jeti Opto 75amp. This heli really does sound wonderful in the air on it's wooden blades, as it's only running 1500rpm on the head and it's quite heavy so it's very slappy and choppy, very Bell like.
It has plenty of scale power though, with enough in reserve if you do something silly.

fr8dog like the taildrive solution, very elegant.

bearings

fr8dog I was talking with another chap about the conversion and he expressed a concern that the speed the tail rod is spinning, if the bearings would hold up to that kind of wear? What kind of bearings did you us and what speed will the tail rod be turning? Shoudl I buy a special bearing?

Charles

I luv my Bell 47. I still have the wire in tube tail drive and have never had glitching from it or from any similar tail drive that I have used over the years (X-Cell, modified GMB, Kalts and older Hawks and Falcons).

There have been times I did get glitches while flying these helis and many immediately wanted me to blame the wire drives. Every time I found the glitching to be from something else - usually worn bearings.

Consequently I would be a little more leary of the bearing drive ultimately causing glitching if they would start to rust or wear.

Just my 2 cents worth.

That being said - it sure does look scale and keeping then oiled should keep rust and wear to a minimum.

Rotorsport

The bearings I am getting are rated at 97,000 rpm. Does the tail wire turn that fast?

:o

Don't think so where can I get some ?

Charles

bearings

Here........ http://www.vxb.com/page/bearings/PROD/3-32inch/SCB332

They also have 1/8 inch, these are the 3/32 inch bearings. I found some 3/32 inch wire and think I can install these into the original posts. Too bad they are sooo pricey

Thanks to 55crownvic I ordered some too. Since I just got qpcm I'm not sure if I will use them from the start of the build or not. I'd like to hear how it works.

SKYPUP

fr8dog

Do you think that making the driveshaft posts out of aluminum, there will be any glitching problems? Sometimes metal to metal tends to do that. Just wondering what your thoughts were on that.

Dave

55crownvic,

The bearingposts are on the same electrical potential as the tailboom, so are the bearings and the driveshaft there should not be any glitching coming from this setup as opposed to the drivewire running into a hollow brass shaft. With proper bonding the original setup could be made to work ok as well, see article in helicopterworld where the author describes the de-glitching of the 47 in the review.
I just think the bearing setup is a lot cleaner, eliminates possible glitching and looks more scale. To date my setup has been performing excellent without any problems.
As to a previous question regarding the bearings, any good quality bearings should be able to do just fine with the speed of the driveshaft.
fr8dog

couldn't use use a plastic tub instead of the brass one and use the stock wire without grease to avoid the glitching. The was one suggestion from Century.

BGM

I spoke with a San Antonio Century field rep last night who stated he uses 3/32 music wire for the drive wire (largest diameter which will will fit the stock brass tube). He uses tri flow silicon lubricant on the wire before insertion into the brass tube. He stated he has no problems with glitching using this set up and the heavier drive shaft gives better performance than the stock one which is smaller in diameter.

SKYPUP

skypup

hmmmmmm. Thats interesting. Something else to consider. I have my aluminum brackets made(like fr8dog's), using 3/32 inch bearings and wire, but havent put it all together yet. Was also thinking about cutting the tube off between the support brackets. Leaving just enough of the tube in the bracket to act as the bearing. That would give less area of tubing for glitches to happen. What do you guys think of that idea?

Dave

Hi Dave

I spoke about that idea with the rep also. He said the method he uses works fine for him. I got my bearings also. Did you try to use them with the stock brackets? My 3/32 wire does NOT fit the bearings. They don't hold the tolerances very close for music wire and I guess my piece is slightly over spec. To use the bearings I would order drill rod which has very tight tolerances. I need a pic of the rotor head assembly. The pics in my instructions don't match up.

SKYPUP

The wire I got didn't fit either. Just took some sand paper up and down it a few times, now it fits fine. You might have to file the end of the rod. When they cut it, it deforms. Try that first.

My kit came with two extra tube mounts, and I was able to make the bearing fit. Its a little work(what isn't when you are modifying something?) but it looks cool; sooo I cant decide which method I will use. I did go ahead and order the tube and brackets from Century in case something gets messed up, or I dont like that particular setup.

Also, the 3/32 wire does fit the tube, but with the grease I had in there it is tight. Might clean that out as best I can and try that along with cutting the original tube as mentioned in the above post I made.

As for the pic you need, try going to Heli-world and look at their manuals, to see if that helps. Heres the site link.. http://centuryheli.com/support/manu...ll47/index.html

Completed

Well, I finally got my wire drive finished. Will try to post pics on monday. Basically looks the same as fr8dog's, just shaped my aluminum brackets a little different. Looks cool and seems to work ok, but the weather here is snowing, so dont know when I will get to try it out.

Dave

I believe this mod made this thing fly even better than before, nice and smooth!!

WOW

It looks great! Did you need to glue the bearings to the mounts? What type of glue? Also, did you need to drill thru both mount halves to enlarge for the bearing or just one half? Thanks!

SKYPUP