Hello everybody,
This is my first post and I thought I would share my weekend story ....in the hopes that it might save somebody's plane.

I've been flying of an on for some time, but really got serious and joined a club just this past year. (i got tired of crashing). without bragging too much, I've done really well with my trainer and even some of the old guys commented on how well i've come along. For christmas I recieved an ultra stick .40.....I've heard many great things about these planes and I was very anxious to get her together and try out those flaps. well after a few evenings I got it all together and after another week I worked out some binding issues, some computer radio isssues, adjusted the throws, tuned in my engine, balanced the plane......basically polishing all the technical things....(or so I thought) and waiting for a break in the weather for the maiden flight. well saturday was the day. it warmed up enough and the wind was down to about 8 mph.

So I packed up all my gear, my ultra stick, and my trainer plane. I flew the trainer to get my thumbs warmed up and after i got my reflexes in gear I fueled up the ultra stick. after taxiing around a bit and getting a feel for her, I got the stones to get her off the ground. And away she went! Didn't even have to trim her out. I noticed my ailerons were a little too sensitive so I brought her in and she landed like a bird.....almost harriered in. I actually barely made the runway!!! I was STOKED!! I made the adjustments on my radio and got her back in the air. after a coupld of laps , the engine started sounding a bit different. THE a POP! ( like a backfire) So i tried to bring her in again and i noticed that the engine would only go down to a fast idle. I was soo concerned with this that it took me a second to realize that my flight path was headed for the pits. Everything happened so fast that i decided to bank away from the pits and get her back up for another go around. well the engine had just enough "umph" to get me to an altitude that was too low to swing her around for a landing, and just high enough that i couldn't force her down.

After inspecting the scene of the crash I figured out what happend. My muffler fell off in flight. this plane is set up to have the muffler hang off the bottom of the plane. the screws vibrated out and the muffler came loose.
The lesson of the day is to use locktite on your screws. Instead of using a few drops of locktite, I now have to spend $130 in a new ultra stick. It's an expensive lesson for me, but maybe not for you.

Sorry about your crash. It is also a good idea to retighten all of the screws on your engine after it has been warmed up. The use of locktite on engine screws may or may not be the way to go, but if you tighten the bolts when the engine is hot, they tend to stay put.

Good luck on the replacement plane.

That is true....I just was planning on running at least a tank through it before i checked the muffler screws...haha. You know I didn't think about the temperature of the engine may be too hot for the locktite to do it's job. I need to check on that. Just wish i woulda taken the time to look it over after i got it down the first time.

I have also heard of using 2 nuts (double-nutting) on the muffler. The last nut helps keep the 1st one from loosening.

you would be better off using some of the hi temp [irange\red]rtv on the threads and inder the heads,will stick hust enough to prevent turning from vibration.

I think the entire muffler fell off, not just the back half (which is how I read this the first time). SharpProp, do a search here and you'll see a post by RCKen showing how to secure the back half of a 2-Stroke muffler. Sometimes the engine's vibration will work the nut securing the back half of the muffer free in flight. You then hear that same noise you described in your first post - yeah, been there, done that.

I use Ken's method of securing it with wire. A jam nut also helps if the bolt is long enough. Of course, none of this helps if the whole muffler departs from the engine

Food for thought ...

-MA

Sorry to hear about such a crash and for such a reason. However let me save you some trouble as you need not try to patent "muffler loss". IT HAS BEEN DONE BEFORE!

Back in my early RC days when using a muffler was a relatively new thing, many engines could only accept the strap-on mufflers. Then as engines started being manufactured with bolt-on mufflers, I think I planted a couple dozen in the farmland around the fields. KNOW WHAT? NOT ONE ever sprouted up and grew mufflers! DRATS, bad seeds I guess! [X(][:-]

However in the past 30 years I have learned one thing, and when I don't do it I generally plant another muffler. That thing is to retap the muffler or engine case -- where ever the mufflers screw into -- to a minimum of 6-32 -- and uses black steel Socket-Head bolts to hold the mufflers on any engine .25 up to a .90. Above that use #8s and 1.20 & above #10. I don't recall losing a muffler when I do what I know will work. Now being lazy, I don't always do the right thing and then I pay the fiddler! So, second time it gets done!

Best of luck in the future.

The real kicker for me as I replay the event in my mind, is that when i tried to land it I should have focused on the landing and got it down....I let the pitch of the engine distract me.....as I thought it was coming in fast. The truth is it probably wasn't but just "sounded" faster. Just wish there was a "do-over" button on my new computer radio....haha.

Just so we are clear the muffler didn't lose the back half.....the whole muffler departed from the engine. and the two screws do not have bolts on the other side. In fact I don't believe they even come out of the other side. Probably if I would have tightened it when the metal was hot, I would not have had this happen. I also like the idea of the high temp rtv. Man this hobby has some expensive education...haha

SharpProp

Sorry about the loss. I'm sure you learned a lot from this incident and hopefly pass it on when you start instructing others so they don't have to learn from Murhpy's School of Hard Knocks.

One good lesson to be learned here. With any inflight emergency, regardless of what it is, you have to concentrate on flying the plane first. Having control of the plane, knowing where it is at and where it is headed is crucial for everybodys safety. If it's out of control, or going to get into that situation, then you may have to think about just putting it in, especially when it is heading for the flight line.

Hogflyer

Luckily nobody else was at the field that day......therefore the flight line was clear.....but you're right. just two seconds of thinking of the engine sound instead of the direction of the flight path and on a different day somebody may have been hurt. it should have been center of the field, and straight before I thought of getting that engine idle down.

I have never lost a 2 stroke muffler (knock on wood) But have lost several 4 stroke ones.
I have started using blue loctite and have not lost one since.

In a situation like this it's important to first get the plane DOWN, even though your instinct may tell you it is too high or too fast.

You can cause the plane to bleed off a lot of speed by pushing onto the grass even if it bounces a bit... and let it run off the side of any runway.

At worst you may get a broken prop this way...

Augering in does far more damage.

G'day Mate,
After reading your post, the first thing I noticed was the fact that you are basically a beginner, I'm sorry you damaged your plane, but, the one thing that was not mentioned was the fact that vibration will cause nuts & bolts to come loose, so balance your props, no matter what size they are, I read lots of posts on here about fellas who "never balance a prop" & have supposedly, never had a problem, if you can cut down on vibration, you won't need any sort of locking compound.
And you didn't check over ALL the fasteners on your plane, after the first flight, while everything was still hot, this was mentioned above.
Next you did not have an experienced pilot helping you, by double checking you plane, & standing by during your first flight, most times a calming voice can mean the difference between a crash & an undamaged plane.
But one thing is true, you have learned a valuable lesson, & all the best in the future.