Still Teething problems

Just when I think I am finally convincing the Mustang to behave itself something weird shows up. I had a fuel leak in the tank, OK not problem, bring out the soldering gun. Had some junk in the fuel filter, no problem, this is normal on a new homemade take, replace fuel filter. Got the launching problem fixed, don't give up on take off.

Last night I finally got things working enough that I got consistent runs from one flight to another so I can figure out how much fuel to put in. I also got things stabilized enough so I can do the entire pattern for the first time. I had great weather. So I finally got about 4 or 5 full patterns in. Did some normal adjustments and the like. I was very happy. It was turning well and also grooving. Still needed some minor tweeks but I was well on my way. I figured that I could get it ready for its first contest in Sellersberg in 3 weeks. I was really happy. Then I cleaned the plane. I was not happy. I cleaned off the canopy and noticed it still had oil on it. On the INSIDE! Oh Oh.

So, after I got it home I pulled the engine and tank and looked inside the tank compartment since that was the first logical place to look. I had covered the inside with epoxy glue when I built it but the strange thing is I could reach in with a tweezers and literally peel it off the plywood. First time for that one. I sprayed some K2R inside the compartment to see what the damage was and to my suprise I did not have a bunch of oil there. I had a light coating but nothing major. This morning I only had a small drop in one corner. Weird. This had to be where the oil is coming from but I expected more soaking. I did have the where with all to line the bulkhead and tank bottom with 1/64" plywood to help prevent soaking because the plywood is a harder wood than the balsa.

Now for the real worrysome part. I noticed also while I was cleaning that a line appeared on the wing and the fuselage where the fillet piece would start and end. I am wondering if the fuel seaped along the fuse/wing joint and is contaminating the joint causing the balsa fillet to swell. If so, I will need to remove the fillet, dry out the joint with K2R and reapply the fillet. Not looking foreward to that.

I was hoping to have it at the Nats for photo ops with the Brazilian guys but I cannot get it done in time with work and flying. Since it is just on the outboard side, I could just put the plane down and say take a picture of the inboard side only. It would be kinda like the original model of the Enterprise where they could only shoot it from one side because of all the electrical wires duct taped to the other.

I am still not sure how I should proceed in determining the best way to find out if the joint is contaminated. We shall see.

Matt --

Great note! Now, what the heck is K2R?

K2R is a spray can of powder that absorbs oil. Kinda like talc in a can mixed with thinner. Sorta, kinda. Best used in the open air. It really gets into cracks, crevases, folds, etc. Usually takes two tries to get all the oil out. Sold at your friendly Ace hardware store.

K2R is a spray can of powder that absorbs oil. Kinda like
talc in a can mixed with thinner. Sold
at your friendly Ace hardware store.

I tried every ACE Hardware in NW Galveston County - NO K2R. I get mine from Richard Oliver. $6/can or $24 for a 6-can box +tax +shippping yada, yada. . .

Ralph Wenzel

Apparently corn starch and alcohol work, too..

LAST EDITED ON Jun-07-06 AT 09:39 AM (CST)
 
Ralph,
The ACE in League City carries it.

By the way... where did Odessy Hobbies move to?

LAST EDITED ON Jun-06-06 AT 03:59 PM (CST)
 
Any oil in the tail hatches? Is the outboard gear installation dry?

>Any oil in the tail hatches?

No. I took the hatch off after I got done flying tonight. All is dry as far as the eye and flashlight can shine. This was a really good idea, thanks. I can shine a flashlight almost under the entire cockpit area. However, I am having trouble seeing the corners that I really want to get too. I will see if anyone has a small penlight I can borrow so I can shine it up even farther.

Is the outboard gear
>installation dry?
>
>Al

The gear appears to be dry also. The wing center section is covered in two layers of fiberglass and epoxy so the center section should be sealed. I hope.

Maybe a Stuka pilot is jinxed by changing to a P-51?

What Larry said..............

Fly Safe John

QUOTE: I had covered the inside with epoxy
>glue when I built it but the strange thing is I could reach
>in with a tweezers and literally peel it off the plywood.

Although I am not in your league at all, I like to put in my two bits about the epoxy. Putting epoxy or epoxy glue on raw wood something times goes wrong. I have had the same problem you have now. IMHO it has to do with the two component character of epoxy and the natural capillarity of wood.Apparently the epoxy manages sometimes to "come apart" in the wood.Applying the epoxy, you have to mix really well and let the stuff begin to cure before applying to raw wood. An alternative would be to treat the wood with nitrate dope( cellulose dope).This is micro porous and will accept the resin.It is my contention that the final adhesion greatly improves.

I like your use of the k2r ! I have been playing with it in removing oil from raw balsa, just to see if works. And it does! In the old days you could buy pure chalk powder(not talcum) at the drugstore. The gimmick was to find a solvent the would not make the oil penetrate further, but at same time make the chalk stick to the wood.Very difficult to do! K2R does the trick perfectly.

LAST EDITED ON Jun-07-06 AT 04:28 PM (CST)
 
Matt,

If your epoxy didn't stick, I'd think that the wood was somehow contaminated or the epoxy wasn't mixed well or was possibly old. In any case, I'd prefer to put epoxy on balsa than plywood to get penetration so that it wouldn't be possible to peel it off. Also, I prefer to fuel proof my engine/tank compartment by first, using thin epoxy and strips of fiberglass onto every intersection then a coat over all of the wood in both compartments. This is followed by a coat of epoxy paint. I usually paint my engine compartments black with a strip of white over each intersection so I can detect cracks which may form from the stresses of flight and maneuvers before serious contamination takes place.

[photo not recovered: 448744e37fb0b3ce.jpg]

Here is a photo that shows a bit of white on black inside the cowling. As luck would have it, I did detect a crack starting to form between the motor mount and supporting structure. I was able to repair the area before any contamination happened and redesigned the engine installation to prevent its recurrence on future airplanes, including the Critical Mass, which has a nearly identical nose structure.

If you built one of those tank compartments where the tank slides in, then the odds are that your leak is there. I had open bypasses from the engine compartment to outlets over the wing on the Sea Fury. When I made a repair, I found contamination inside the airplane. when I built the second Sea Fury, the same thing happened again in spite of my best efforts to seal the area. I think it is nearly impossible to seal the inside of a box.

>Matt,
>
>If your epoxy didn't stick, I'd think that the wood was
>somehow contaminated or the epoxy wasn't mixed well or was
>possibly old. In any case, I'd prefer to put epoxy on balsa
>than plywood to get penetration so that it wouldn't be
>possible to peel it off. Also, I prefer to fuel proof my
>engine/tank compartment by first, using thin epoxy and
>strips of fiberglass onto every intersection then a coat
>over all of the wood in both compartments. This is followed
>by a coat of epoxy paint. I usually paint my engine
>compartments black with a strip of white over each
>intersection so I can detect cracks which may form from the
>stresses of flight and maneuvers before serious
>contamination takes place.

My 02 Stuka had the motor mounts started to crack just before its first Nats. I was fortunate to have caught it before they let go totally. To fix that, I had put some epoxy in the joint and put some fiberglass along the joint to reinforce the joint. On my Snake Stuka, I did that from the word go. However, I forgot to put the fiberglass cloth on the Mustang. Probably from a product of starting it 2 years earlier and then putting it on the back burner for a year and a half and then finishing it. I am planning on putting fiberglass cloth on the joints inside the tank compartment. It would not suprise me that the glue would be old. This is the first time that I had any problem with the glue not sticking. Usually I heat it with an old hair dryer to thin it and to get it to soak in well. I did make the fuel tank to come out the front like most stunters. Normally I do not get much oil in the tank compartment but the Mustang seems to be messier than normal for some reason. I have to find that leak.

I have never had any luck with trying to seal up boxes in the firewall. I have better luck with tanks installed through the open bottom. semi-scale nose structure will usually tolerate this installation.

Matt,

Did you slove your problem?

>Matt,
>
>Did you slove your problem?
>
>Al

I borrowed a small flashlight and found out that the inside of the fuselage is clean. Good news.

I have been able to go out and fly all this week after work so I have not had a chance to work on it much. I plan to work on it this afternoon after I mow the yard.

I have sprayed K2R inside the tank compartment a few times. The last time I just left it sitting for a couple of days. The first time or two I spotted a small wet spot on one of the edges. After a time or two this dissapeared. After brushing out the powder after each step, I left on the last coat to see if anything soaks back through. So far so good. I plan to use epoxy and fiberglass cloth in the corners to help seal things.

I plan on bringing the engine and muffler combo to Dad's next weekend to check for leaks. He has the test stand right now. The side of the fuselage is quite wet which is unusual for a rear ehaust engine. I obviously have a leak somewhere in the joint between the muffler/engine or something else that I need to find.

LAST EDITED ON Jun-11-06 AT 02:14 PM (CST)
 
"I plan on bringing the engine and muffler combo to Dad's next weekend to check for leaks. He has the test stand right now. The side of the fuselage is quite wet which is unusual for a rear ehaust engine. I obviously have a leak somewhere in the joint between the muffler/engine or something else that I need to find."

Matt
I would think Dad could afford his own test stand.

>Matt
>I would think Dad could afford his own test stand.

Yes, he can, but he is the one with no neighbors. Gotta keep them happy.

Anyone else notice that Matt is beginning to write as well as Leonard?