Hi,

I'm new to X-Cell machines and have a gasser that I picked up this summer. I was having vibration problems and found the blades going out of track when adding collective.

I have checked everything and main and tail shaft don't have any runout and I have the fan and clutch also running true.

I've decided to replace the head and associated parts as I found some wear and some things that were a little questionable. The spindle in it was from what I understand a Bergen with a black ring around the center of it. According to the instructions for the machine the spindle should have a piece of fuel tubing on it. Which is the better way to go?

It also looks like the damping shims (0329) are all distorted so I guess I should get a new pack of them also.

Any other tips on head assembly?

Hey Scott

the plastic collar does the same thing as the fuel tubing, so that in an of itself won't cause the problem.

I gather you got this second hand, so you probably can't be sure about its crash history.

Make sure the spindle is straight and not bent. Check each bearing individually to make sure it is smooth with no notchy spots. If any are, replace them.

Look at the blade arms to make sure they are straight (if plastic not cracked) and look at each mixer on the blade arms to make sure they are straight. Last time I had this problem it was because one of the mixers was bent.

Also make sure the thrust bearings are good, not damaged, lubricated, and installed correctly. If a thrust bearing is installed backwards, it will cause tracking problems.
Gordie

Thanks Carey and Gordie,

I appreciate you taking the time to answer here.

I have a lot of new spare parts that came with the machine and I'm replacing everything I can in the head. I have new bearings and have checked them all and they are good. The only spindle that I have is a MA one but no fuel tubing. I'll order some and some new shims from Ron Lund tomorrow.

I also would like to put a good set of glass or carbon blades on to eliminate possible problems with the wood ones that came with it. I'd like to use 700mm but don't think I can with the stock tail blades. Any suggestions here?

If you drop your tail blade length from stock to 95mm, you can run 700mm blades with no problems. The Gamma 700mm blades that MA brings in are a good value. They can be had from the various dealers for well under $100 a set. For a bit more money, you can choose the MAH 690's. SAB and TG make excellent blades in the 680-700mm range, too. If you will be a bit more specific about your intended flying style, I can suggest particular airfoil types. It all depends on how much inverted work you wish to do.


Ben Minor

Thanks Ben,

I'm not a 3D pilot by any means. More FIA style I guess. Like working on smooth big maneuvers.

The gasser has a Hanson engine in it with stock X-Cell fan and gearing. 14 tooth pinion and 90 main gear. I also have Bergen CNC fan with 12 and 13 tooth pinions.

I pulled the Bergen stuff out when chasing down the vibration but that didn't change anything. I know now that the spindle was slightly bent and some other problems in the head.

I don't think you're going to have a lot of success with the smaller pinions, but of course have fun if thats what you want to do.

If you really want nice big maneuvers, get either the 32.5 or 33" tail booms and run the Hi Products 720mm semi blades with the stock gearing and the s/s steel muffler that MA sells.

The big blades help with blade loading. Typically the gasser is around 13-13.5 lbs, which is quite a bit for short blades.

If you make these changes, make sure the CG is still on the mainshaft or further forward. May have to use bigger battery packs to get there.

You aren't the first to recommend staying with the stock setup. I do have the MA Stainless exhaust. I flew the machine when I first got it and it had loads of power and flew nice. I was pulling 11 degs of pitch with the stock wood blades. It just had a vibration around 1700 rpm. I'm hoping it will be fixed with the new head and parts. I found several things slightly bent and worn.

The small hub through the head that the flybar goes through had bends in the end shafts where they go in the bearings. Also the plates that hold the flybar bearings were slightly bent. That with the spindle bent. I'm hoping the rebuild will take care of all that.

Hey Scott

If you're saying that it runs smoothly, until you get to 1700RPM or more, there probably isn't a head problem, its probably the engine.

using your setup, use regular gas and either Yamalube2 mixed at 32:1 or AMSOIL at 50:1 (its good to 100:1 but there isn't a lot of leaway for any mistakes at that ratio). Set the low end needle for around 7/8-1 turn and the high end around 1 and 1/4 turns. Filter the fuel at every step, and use a good quality filter on the model, its amazing how much garbage is in gasoline.

take a look at the primer bulb when you set the model down from flying. If its still got fuel in it, all is well. If its empty, hot air is blowing on the carb and causing the regulator to misbehave.

I spent hours on the phone with Bill Meador about the engine. I have all the linkages set as he suggests and the plug is a nice light tan with the needle settings I'm at now. I'm using Amsol at about 65:1 in it. There is what I'd call shaking in the skids and canopy when hovering at about any RPM really. Just worse up at 1600-1700. Not what I'd relate to an engine vibration. Thought that at first and spent a lot of time getting the engine and all set up right.

Then I saw the blades going out of track when adding collective to climb out so started looking at the head. That's when I found a lot of worn and slightly bent parts. I'll see what it does when I have it all back together.

Carey,

I completely rebuilt the head with all new parts and am using the Gamma 700mm blades.

It isn't any better with the shaking. 1500-1600 is ok but when I get up a little faster I can see the canopy shaking as well as the gear. The mainshaft is true and everything is balanced as I can get it. No more going out of track when adding collective and the machine climbs out like a rocket.

When in a hover at 1700 I still have a miss in the engine. It's just a twitch every second or so. I also see that in forward flight although not much when at full throttle. This is a Hanson engine, are the needle settings any different? I'm going to try a new plug and some new gas mixed 50:1 with Amsol this weekend.

I Love the machine and how it flies, it's a real powerhouse with those 700mm blades, but I need to get the engine sorted out.

Hey Scott

I've had good luck with both Yamalube 2r at about 36:1 and AMSOil as high as 75:1, although at the high end of this, there isn't a lot of room for any mixture mistakes.

Generally, setting the low end at around 7/8 and the high end at 1-1/4 will work. There is a spot where the two interact and you can lean the top end very slightly and affect the hover setting, depending on the RPM's you run. I'd suggest setting the top end around 1-1/8 and see if it gets the twitch out.