qspilotcmh

Hello,

I am running a 4 year old OS 46FX on my OMP Edge. The motor has approx. 200 flights with no crashes.

I am having an issue with midrange power. When I pull into a hover I am normally at idle. I will add approx 1/3 throttle to start the hover, however when I have to add a little more to hold the hover the motor will quit for a split second. It will then catch up and produce plenty of power to pull out. During normal flight attitudes I don't notice it. I can go straight up at full problem with no problem. As you can imagine with the motor stalls at 20' the plane starts dropping rapidly until the power comes back!

I have tried adjusting the low end and high end. On the bench my low end seems ok, with a smooth transition from idle to full or half throttle. My high end is running 200 rpm rich of peak. I have tried Wildcat 10% and 15% nitro and I am currently running CoolPower 20% Heli and they all do the same thing.

I have also tried an OS #8 and A3 glowplug. I am running the stock muffler with the baffle out. The motor is turning an APC 12.25 X 3.75 @ 12,100 RPM's. I tried an APC 11x4 with the same results.

Any suggestions as I have tired everything.

Thanks

ThumbSkull

My Feedback: (57)

Do your tuning while the plane is upright like in a hover. The tuning will be slightly rich when horizontal.
The hesitation sounds like you are a bit lean in that attitude. If all that checks out then your problem is with the fuel tank.

Loosen the grip on the tank. I run 2-3 rubber bands to hold the tank on and all the foaming issues go away.
If you use straps or zip ties they let the tank vibrate too much and air in the fuel causes leaning.

I like the Hayes tanks or if you use something else, then use the Dubro sintered clunk.
Try a 12x4 Xoar on that setup after you get this problem solved.

qspilotcmh

Thanks I will try adjusting it while someone is holding it vertical.

I have 3 pieces of foam between the tank and the aircraft. I am using zip ties and the tank it loose. I thought loose would be better than too tight as the airframe does vibrate a lot. Maybe I'm wrong and need to tighten it up some.

I was thinking about getting a different tank, however my tank has two grooves in it for the zip ties. I guess if I went to rubber bands it would not matter. I'm not sure how I would connect them through the 4 holes on the airframe. Do you have a picture for a suggestion? I has 4 holes to mount the tank 2 top and 2 bottom which the zip ties run the vertically.

ThumbSkull

My Feedback: (57)

This is with fuel line instead of rubber bands but you get the idea.
Wood dowels sharpened like a pencil stuck in the end of the fuel tubing hold in the holes in the fuse quite well.
With rubber bands, just make a hook from wire to poke through the holes or screw in small j-hooks.

There is 1/2"foam under the tank so the tank is quite free moving.
The idea is that the fuse can vibrate all day long and the tank can stay still.

freeair

make sure your prop is perfectly balanced. this will stop alot of bad vibes.

qspilotcmh

Thanks for the pictures! I will try it this weekend.

Are you running a Macs Muffler on the 55ax? If so do you notice more power with it than the OS muffler with the baffler out?

I looked for a 12x4 Xoar and I can only find one for electric motors. Do you have a place you order them from? Do you happen to know what rpms the 55ax is turning the Xoar 12x4 with the macs muffler? I get 12,400 RPM'S at peak with my 46FX using a 12.25 x 3.75 APC with the stock muffler without the baffle.

Thanks for your help!

qspilotcmh

Yep it's balanced using my magnetic balancer. I sanded the back of the heavy blade as even as possible until it balanced perfect.

I still have some airframe vibration at idle. What method do you use to balance?

flygilmore

Use a Macs header and build yourself a Mousse Can Pipe (check out t h e p r o f i l e b r o t h e r h o o d . c o m) and get 14,000+[:@] out of your .46 using an APC 12x4!!! Trust me, very worth your while to research this. You can PM me as well....

ThumbSkull

My Feedback: (57)

The macs one piece muffler is somewhere in-between. I have a macs one-piece muffler on my 55AX and 160FX and it's good. It did make the midrange a little burbley but not bad. The high end got a little boost. The big benefit of the one-piece muffler is the weight savings (2.2oz on the 55AX and 6.2 oz. on the 160FX) over the stock muffler. Like Gilmore said, you get more from a MCP and a macs header.

GO TO


to learn about profiles.

qspilotcmh

Thumbskill,

Where did you buy the Xoar 12x4 prop? I looked on xoarintl.com and they don't list a 12x4.

ThumbSkull

My Feedback: (57)

Here is two places. I have ordered from both of them.

[link]http://www.swanyshouse.com/xoar/props.aspx[/link]

[link]http://www.texas-hobbies.com/props.htm[/link]

qspilotcmh

Thanks!

qspilotcmh

I tried adjusting the mixture and throttle trims with no success. I then ordered a tower muffler and hayes 6oz thank from Tower hobbies. I don't know which one fixed the problem, but my plane is running awesome. I picked up 500 rpms with the Tower muffler and I have very smooth throttle response. Over 50 hovers and not one engine lag. I added the Xoar 12x4 from swanyhouse and it's running even better!

Ernie Misner

Thumbskull, nice pics! What are the little laminated blocks just head of the wing/behind the tank area for? Keep the tank from moving back while loosely held?

Thanks,

Ernie

ThumbSkull

My Feedback: (57)

Those are plastic blocks that hold the base of the wire landing gear.

jerrysu29

More than likely what fixed the problem IMO is the Tower mufflers supply more back pressure which in turn supplies more pressure in the fuel tank in this keeps the fuel flow constant even in the Hover. Any time you remove the baffle from a muffler you loose some of the pressure needed for fuel supply, but then again you could of had an air leak in your other tank setup, aerated fuel and we could go on and on, Nice to hear your problem is solved though there is nothing worse than an unreliable engine when Flying 3D !!!
jerrysu29 Call Sign Wild Man