Head speed question

[chrisg3]

Hey Freaks,
I have an older X-cell (circa 2001) 60 Custom with a new YS 61 ST-2, running 600mm blades. I'm still breaking the engine in but I noticed the headspeed seems kinda low. I tached it at about 1400 rpm. The heli kinda bobbles around in hover, however seems very solid in forward flight. What kind of head speed should I be looking for when I start to lean it out?
Thanks in advance,
Chris

[tnreefguy]

I would look at about 1650 or so. That should get rid of the wobble. Do you plan to 3d this bird or just sport fly.

[chrisg3]

Currently, I'm flying a Raptor 30 which I'm doing nice loops and flips with. I'm running 1850 head speed with 550 carbons. I hope to progress into 3d flying as my skills and confidence grow.
I'll try bump up my throttle curve tomorrow and see if the bobble goes away.
Thanks for the help,
Chris

[tnreefguy]

Try the 1650 head speed if you are going to sport fly the model. If 3d go up to the 1750 to 1800 rpm.

[DavidH]

I have an older X-cell (circa 2001) 60 Custom with a new YS 61 ST-2, running 600mm blades.

600 mm blades are way short for that model. With the 30 inch tail boom it came with 640 mm wood blades. It would swing 660 mm blades with no problems with the 30 inch boom. If it has the 31.5 inch boom it will handle 680 to 700 mm. YS 61 ST2 should have no problem swinging 680 mm blades at 1750-1800 rpm. I use to run 690 mm blades with the YS 61 ST2 and would turn them 1850 rpm.

http://www.rchelibase.com/xcell/model/plans/1003981.gif

http://www.rchelibase.com/xcell/model/plans/1003982.gif

http://www.rchelibase.com/xcell/model/plans/1003983.gif

The three links above are the plans for a 1998 Custom 60
http://www.rchelibase.com/xcell/model/plans/
http://www.rchelibase.com/xcell/model/subcomp/index.html

All those links will help you identify the model you have. All the 60 size MA models use these length rotor blades
30 inch boom 640 mm to 660 mm
31.5 inch boom 660 mm to 700 mm

The above is with 100-105 mm tail blades.

David

[Alfred]

Don't run it over 1750 head rpm or you will be over-reving the engine.
The YS likes to be run rich, if you lean it to the point as you would a TT or OS engine, all you achieve is increased temperature and a shorter lifetime. The engine will not sag when run a bit too lean but you just shorten it's life.
The square tank is a bit on the small side and gives me the shortest flight time of all 3 of my X-Cell's.
I have got a Fury tank sitting here to be installed, but it will require some parts to be re-arranged.

[GM1]

Hey David,
I guess when we were turning 1950-2000, we were overreving the 61ST2s. <G>
Gordie

[Alfred]

That would depend on your gear ratio, wouldn't it GM1?
Looking at the models plans, it's the same as my 1003, using the original black main gear and pinion.
At 1850rpm mine screams it's brains out.

[DavidH]

1750 x 9 =15750 9 to 1 is the ratio on the Custom unless it has been changed


We were using 9.3 to 1 ratio 1850-2000 rpm as Gordie mentioned.

9.3 X 1850= 17205 rpm on the engine

9.3 X 2000= 18600 rpm on the engine

Yes we were turning the ST2's when we were using them . They didn't seem to have a problem with it.

David

[Alfred]

Practicle rpm = 2000 - 18000 rpm
So you were running them well past their powerband.
Must work alright on 30% Nitro
Doesn't seem to work well on 20%