metal in oil
 

Hey guys, I just had a couple of quick questions. Had a great day of flying today, but I noticed when cleaning my plane that the castor residue had a lot of metal particles in it. Plane was running great, like a spotted ape. The more I flew the faster it got. It's a super tigre gs .40, that has about 20 flights on it, broke the engine in with a 12x6 cut down to 5.5x6 at 16,500 real rich on a stand, flew the first 10 or so flights slightly rich slowly leaning. The last 6 or 7 flights I have had a 9x7 apc on it, running really well, but not too lean. Today I got my 9x6.5 apc pylon prop on it, tuned it up and let her go, and like I said the more I flew the faster it got, all along with a nice smoke trail, but there was metal in the oil. Could this just be from the engine (obviously) still breaking in and having more load on the plane due to hard flying? Never had one do this before just curious if anyone else has seen it. I know they do it at first but it had already stopped until today. Question 2: when coming out of the turns, my plane dips down real bad, not abnormaly just like any other would. This obviously requires compensation and drag to correct. I was thinking that I should dial in some right rudder trim, to help it like a knife edge, as to not have such a drastic downward angle out of the tight turns. What do you think, any advice? trying to get my laps as smooth as possible.

RE: metal in oil
 

Hopefully, the metal is from a slightly loose muffler. Put in a new glow plug and make another flight. Then carefully inspect the plug and element to see if an metal has attached.

The nose dropping in the turns is usually due to the higher angle of attack of the downward blade in the turns, since the airplane is pitched up at least 4 degrees relative to the path of the airplane in the turns. Since the blade on the right side is doing most of the pulling, you end up with the nose down tendency. Most have to put a small amount of weight on the right wingtip to compensate. Some are experimenting with electronic mixing schemes to compensate. Lead tape from a golf shop works for me.

Other possible problems that can result in this is being slightly nose heavy, or having left trim in the rudder or even left thrust (though that causes problems on takeoff).

RE: metal in oil
 

Also, measure your elevator travel. You may have the right side V-tail (if it's a V-tail) traveling further than the left side, which would cause the tail to come up in the corners..thusly pitching the nose down.

RE: metal in oil
 

Do you have any differential dialed in? Sometimes you can correct the angles in turn by dialing in a little bit of the aileron differential or lessen the down trim.

In other words, don't make the downward aileron go down as far.

I think I'm saying that right. :eek:


Hope that helps.

;)

RE: metal in oil
 

how would I adjust differential with only one aileron servo though? It does have a differential problem as it yaws badly if you pull an upline and do a roll. I could drill out a round servo wheel with the holes behind the output shaft, wouldn't that change the differential? If I am visualizing correctly that would take it out. The ailerons go down more than up.

RE: metal in oil
 

There's your problem.

The nylon "ears" used on 80% of the aileron installations out there tend to put the attach point of the pushrod ahead of the aileron hinge line, which effectively gives a little bit of forward rake on the horn. (I know it's a wire with a nylon ear on it, but think of it as a horn.) On a low-wing airplane, that's exactly what you want. If the servo arm is straight across, that little bit of rake on the horn causes the servo to pull the aileron that it's pulling just a few degrees more than it pushes the aileron it's pushing.

BUT ... on a high-wing airplane like most of today's Q500 racers, that same angular difference gives more down aileron than up. The solution is either to bend both horns back a few degrees, or (as you suggest) use a round wheel on the servo and drill your pushrod holes a few degrees ahead of the center. Now you have the same rake at the servo as you have at the horn, and the aileron travel will be the same amount both up and down. Season to taste. [8D]

RE: metal in oil
 

Thanks I'll give it a try, the more and more I fly this plane the more I love it. Cant imagine what it'll be like when I get all the kinks worked out.

RE: metal in oil
 

Do not mess around with control surface offsets. Correcting the nose down in the turn with offsets will screw up something else. Get all of your surface throws symmetrical with their mate.

Correct the nose down tendency with a tip weight on the upper wing and/or move the balance point back. Do it gradually. It may take several flights.

Ed S

RE: metal in oil
 

Im gonna play with the weights also, but I do need to get the ailerons set correctly, like I said it yaws badly with aileron input due to them going down so much further than up so I will get them even and see what happens.

RE: metal in oil
 

Alright guys, tried to get the turning a little better today. Just for kicks, I tried some backwards laps....... Absolutely beautiful, good exit with no drop. So I figured that eliminated the C/G problem. I then also remembered that in trying to do the "right thing" I had added 3/4 oz. of lead to the left wingtip to laterally balance the plane, so I promptly got out the exacto and removed it. Needless to say it helped out a lot, but I think it still actually needs more weight in the right tip. It's also still blowing out a lot of metal, I have some pics to show that, I am 99 % sure its the aluminum from the case that the crank is taking out, it has been stiff and is starting to loosen up. I bet anything there is a shiny spot on the crank you can see yourself in. Let me know what you think.

RE: metal in oil
 

I would suggest that you take the engine apart and see whats shiney! that can NOT be good on the piston to sleeve fit [&o].

RE: metal in oil
 

YIKES!!!!!!! I can honestly say I've never seen that before? [X(]

Definately ain't no burnin glo plug.....

WillFly, educate us after the surgery.;)

RE: metal in oil
 

Will do, i'll try to tear it down this weekend. Bummer though sure was hopin I would get to fly this weekend mabye its not tooo major. [&:]

RE: metal in oil
 

Hey, just saw your thread, I had a case like that, an old MDS heli engine. Turned out to be a wrist pin circlip that came out and wedged inbetween the piston and cylinder wall, grooved the piston etc. until it finally blew out the exhaust port. It was still running fine, probably would have a while longer too but I was so curious to know what it was I went in for a closer look.

I don't know what type of wristpin keeper supertigre uses, just my thoughts, I'll be watching your post to see how it goes!

RE: metal in oil
 

IMHO.... If that is a new engine... I would not take anything apart but would instead return it and exchange it for another. You can even send a sample of that metal grit exhaust. It is obvious from the goo trail you are running it plenty rich for a new engine. There is obviously something wrong inside that puppy. Is that one of them new chinese made ST? May want to get a TT PRO instead.... a little better engine IMO for racing.


Dan

RE: metal in oil
 

Yes unfortunately it is one of the new engines. I got the super tigre becasue that is just about all I run in my other sport planes, the ABC .45's when they were still made in Italy. Strong long lasting engine, but it doesnt look like these are gonna be the same. O well I was gonna get a TT .40 anyhow, im sure this will just speed things along. I'll let you guys know what I find out.

RE: metal in oil
 

ST? You mean SuperTigre? Am I missing something here? Are the new SuperTigre's made in China? [X(]

Oh SNAP!!!! I just bought one on ebay for $40 and should be here any day! :eek:

Wait a minute, The guy said it was brand new & only mounted on a display model and was at least 5 years old. Maybe I dodged a bullet?

=$

RE: metal in oil
 

If it is 5 years old... it is Italian! The new ones are all Chinese... not that that is bad... I have no experience with them personally other than the old ones.

RE: metal in oil
 

Several China built STs around my area .... all seem to be running well in sport planes. Not much difference from the Italian ones as far as I can tell. I don't own one of the newer ones and have not had one apart to see how they look inside but from the outside, they look pretty much the same as always.

Roger S.

RE: metal in oil
 

I can definately say that the new ones are not at all like the old ones, mine has been running well but you can just look at them and tell that the quality has diminished, even in just the casting.I am afraid that thier metal quality has been reduced also.Hopefully I will get this one worked out. I am hoping that some of this metal is coming from some that snuck into the exhaust and is just now coming loose, from when I had to cut the stack and bevel the silencer. I thought I had kept it all out but I could have been wrong. I opened up the backplate, and took the head off, and everything was so spotless that I hated to take out the sleeve piston crank etc. I found no metal shavings inside the engine which makes me think that its all coming from what may have gotten into the muffler. No way to know until I tear it down to the crank. The piston/liner have no scratches or wear, so it looks good so far. I'm gonna run it a couple more times and if it is still doin it I am gonna take it all the way down and a have a look. I really hate to see that they moved production to china, that is a shame.

RE: metal in oil
 

SuperTigre hasn't made a great engine since this G40 ABC. After this, they started making them cheap with cast heads and cast drive washers. Feast your eyes on the high water mark of ST engine development.

RE: metal in oil
 

Excellant example of real Super tigre engineering, The "S" model was nice, but the "G" was the pinnicle of there work.

RE: metal in oil
 

What about the X, performance-wise?

RE: metal in oil
 

The "X" was a great engine and was used for several years in F1 and FAI. The X engine is a rear intake /rear exhaust engine and is not legal for 424 or 428

RE: metal in oil
 

Oh. My mistake. I thought I saw one with front intake. Now that you mention it, it was probably an S.

Now on the G, it's a good motor but you probably wouldn't be competitive with it in 424 right?

I'm thinking more along the lines of an r/c Rossi, Fox, Nelson or Jett am I correct?

Thanks!

Ron.
(Newbie looking for answers)