jayseas

This more of a rant, came back from a disappointing outing of flying.I can't seem to get any engines to run cosistantly.If you have any comments please don't hesitate to tell me.Listen to this video and if you have any thoughts why it is running the way that it is by all means tell me.

http://www.youtube.com/watch?v=kdVpJ6Pn5w8

da Rock

Not sure, but the last couple of falters looked like they happened on outsides.

Tank location?

What kind of tank?

jayseas

Not a very good video to judge from but it is a fox .36 with a uniflow tank.I just can't seem to get any of my engines to run on a consistant basis.

Jim Thomerson

You need to move your tank up or down (can't tell which) a little bit. Also set your needle a couple of clicks richer. Speeding up on insides suggests tank is too low. Once you get the uniflow in the right place, it will run exactly the same both ways. It can be a matter of 1/32 - 1/16 inch one way or the other.

icerinkdad

When you landed was the engine hot? Duke Fox used to suggest that folks take off rich as many of his motors (other than the Fox stunt) will lean out quite a bit in the air. It almost sounded like an over lean run. Change things one at a time. Start by trying fresh fuel. If that doesnt make a difference try changing to another glow plug. Then flush out the fuel filter. By changing things one at at time you can isolate the problem.
Bob

vauxhall

Jayseas, can you post a picture(s) of your engine and tank setup?
Launch the model with the engine a bit rich, it'll lean out in the air. If you look at this video of my Twister with a Fox.36, you hear how rich the engine is tuned on the ground. My pal thought it was too rich, he lifts the nose of the plane and the revs. pick up immediately. It was fine in the air too.......John
http://www.youtube.com/watch?v=lIwV0ZAviW8

Dwayne

This looks like a combat plane if so you don't need a uniflow tank what you do need for the old Fox .36 is presure, put a preasure fitting on the backplate and attach it to the uniflow vent then block off the overflow vent, this should fix your problem.
Good luck and let us know how it goes
Dwayne

jayseas

If i run it with pressure, how should i set the needle valve when on the ground rich or?
Also i can't show a picture, what you didn't see at the end of the video was the crash, and that's ok it was a learnig experience on building a combat wing, what works and whay doesn't.I did learn quite abit, so hopefully the next version will be much better.

Dwayne

Set the needle flat out then back it off two clicks. Also try a tank like this (if it will fit) I know it's uniflow but you can set it up to have the vents on top of the plane to make things easier
http://www.brodak.com/shop_productde...ProductID=6337
Dwayne

gcb

jayseas,

A few ideas:

Although it may be an illusion, it appears to me that the tank is picking up vibration. Make sure the tank is isolated from the plane's vibrations. A vibrating tank will make the fuel foam in the pickup line and give you an over-lean setting.

Balance ALL props.

Mount the tank as close to the engine as possible. That will minimize the fuel head between the plane being horizontal and vertical. An old trick for adjusting a needle is to point the nose of the plane up 45 degrees and set it on the rich side of peak. This was before uniflow tanks so it may not help.

What size prop are you using? Too large a prop will cause a big difference in ground RPM and unloaded flying RPM.

From the video, you might have the launcher hold the nose a little high until just before launch to prevent some sputtering.

I hope something here helps. Good luck.

George

Edit: Additional thought...are you SURE you have the uniflow tank lines hooked up correctly?

jayseas

Goerge, the plane is a combat, 2 1/2 oz uniflow tank that is built inside the wing, engine is or was 1/4" away from the leading edge. Lines hooked up correctly.How can you isolate the tank so you get no vibes?I tried several different props from 10" to 8" ran the same.Right now i'm leaning towards the needle valve being set to lean.Also i am balancing all props.

icerinkdad

Not sure my other post made it here... one reason that combat flyers went to bladder tanks is to solve he foaming problem. No foam if there is no air in the tank.
Bob

greggles47

If you are getting fuel foaming, a drop or two per litre of Armourall will help settle it down.

This is a case when more is less - SO don't overdo it!

Regards


Greg

gcb

Some have reported that too much armorall will permanently foul plugs so that they can not sustain a catalytic reaction with methanol so pay attention to the one or two drops.

Some fuels already contain an anti-foaming agent.

jayseas, apologies...I watched the wrong video. [] [&o]

George

JohnBuckner

My Feedback: (1)

This is a classic case where a Bubbless tank will shine. Bubbles and foaming cannot occur and foam wrap or vibration isolation is of no concern. Tanks are simply hard mounted wherever.

You want a uniform run without any hassels then that takes a bubbless, its as simple as that.

jayseas

I got ya John, but they're exspensive, would love to find a cheaper way.

icerinkdad

Cheaper... okay use a plastic clunk tank to hold the largest balloon you can find and a 1/4 to 1/8" fitting from the sprinkler parts area at your local big box hardware. Just leave off the regular plumbing and slip the balloon into the tank to hold it. Atmospheric pressure works fine so no need to run hot exaust gas past a rubber balloon. You will need to replace the balloon every couple of weeks but it works. You may even find a big pill bottle to work instead of the clunk tank.
Bob

Even cheaper is a bladder tank set up like used in combat planes. A couple dollars for a yard of surgical tubing from the same big box. An empty 22 shell for the end plug held with a small zip tie or two and the same fitting from above to connect to the fuel line. You will need a syringe to fill it and a bulldog style clip to keep from squirting fuel all over the place hooking the line back to your engine. Open the needle till you get a steady drip drip drip from the intake and fire it up. You will probably only have the needle open a turn or so.

jayseas

Thanks Bob, I'm trying to fully understand the ballon setup.Can't seem to fully picture the setup.

icerinkdad

Essentially you get a balloon big enough to hold as much fuel as you need without inflating it. Any container can hold it. You fill it carefully so that you have a minimum of air in the balloon (preferably none). Here is a link on doing a bladder... the balloon is similar but no pressure from inflation. http://www.clcombat.info/bladder.html