OS LA .15 Set up and Reliability

Tell us what you do to get the best performance from your engines.

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Lou Melancon
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OS LA .15 Set up and Reliability

Post by Lou Melancon »

<font face="Arial"><b>What follows relates to the OS LA .15 engine. It is based on personal experience. Your results may vary. The information that follows is not necessarily applicable to other .15 size engines. The reason for this article is to provide a proven path to success to getting your OS LA .15 to run well, predictably and powerfully.</b>

<u><b>Opening the box.</b></u>
When you first open the OS LA .15 box, you will find the engine, its carburetor, two muffler bolts, and the muffler. Before you run the engine, for the first time loosen then tighten all the bolts in the head and the back plate.

It would be better to replace the head bolts with 2.6mm X 10mm socket head bolts from McMaster Carr www.mcmaster.com because the OS cross point head bolts are JIS (Japanese Industrial Standard) heads and if you do not have a JIS cross point screw driver you are likely to strip the bolts head as you attempt to tighten it. The muffler bolts are also JIS and can be replaced with 2.5mm X 25 mm socket head bolts also from McMaster Carr or Micro Fasteners. You do not have to replace any bolts for performance but if you value reliability, you should replace them or purchase JIS screwdrivers.

The OS LA .15 back plate is made of a phenolic material and includes the needle valve. The needle valve is exceptional and the best we have found for the engine but it is prone to being broken off in a mid-air collision so we typically cut it off and mount it separately from the engine. The back plate works very well but the bolts (again JIS cross point screws) are prone to loosening. It is a good idea to remove the back plate and smear RTV Silicon (red) sealant around its surface forming a gasket. We also put a little RTV in the boltholes to help them stay secure so they do not back out.

<u><b>Break in</b></u>
You have probably heard that many fliers simply bolt their new engines into their airplanes, set them rich, and go fly. It works for them, but if you want the best performance and gain the most knowledge of your engine, you will put it on a break in stand and follow a disciplined break in procedure.

The OS LA .15 is an ABN engine with schneurle porting and a “pinchâ€
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Post by thojo »

Great post Lou!

I've also revived some LA's by taking them apart and giving them a good scrubing. Once the carbon deposits are removed, they seem to pick back up some RPM's....

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Post by Lou Melancon »

Joe,
I had three engines that really looked crummy. They were all crusted with burned oil. I put the case, piston and sleeve, backplate and muffler in a crock pot filled with anti-freeze. Man that really works to clean them up - it took the blue coating right off of the engine.

It also removed all the burned in deposits from the piston and sleeve. I had to run those engines for about an hour to get them varnished up enough to run well again. Next time I use the anti-freeze cleaning treatment the piston and cylinder will sit it out.

Lou Melancon
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Post by thojo »

Interesting thing, I've gone almost 1 1/2 without loosing any engine parts or damaging any engines. I broke down and cleaned 3 of my LA's and within a month ALL THREE had carbs sheered off!!!!

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Post by The Snake »

I did only one engine so far in anti-freeze, but it work well. It made the case look ugly but runs great now. I tapped my mufflers out. I have alway ran a few tanks and then throw it in the air.

Very nice job Lou, a very detailed report!

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Post by Ed Kettler »

Lou,

Great write-up, but I have a quick question: aren't the bolts on a .15LA 2.6 mm, not 2.5? How do you keep them in? I recall trying 2.5mm as head bolts and had them pop put, even with thread lock.

Ed

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Lou Melancon
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Post by Lou Melancon »

Ed,
You are right about the head bolts being 2.6mm. I used 2.5mm for a while till I got the right ones. I will change the text to correct it. Thats a good catch on the mistake, thanks.

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Post by boiler »

Onother reason the la 15's have bad runs is the fuel nipple in the carb starts to leak. Remove the press fit nipple, clean and lightly sand the nipple and carb hole. Apply JB Weld to the nipple sparingly and insert. Waint one day before running.

Bob Loescher
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Post by montague »

Very good write up.
One thing I found interesting:

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Bladders will yield 500 or more instant rpms <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

That's interesting because a lot of guys (and Lou, I think you were one of them, but I'm not sure) claimed that bladders were ok in SSC because they didn't increase performance over suction tanks. That was a big big argument, and the argument ended in part because everyone swore that there was no actual performance increase, just an increase in reliablity.

Now, you are saying they are a solid 500rpm advantage. That, to me, sounds like a good argument for outlawing bladders from SSC to slow the planes down by a good 500rpm.



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Post by Lou Melancon »

Kirk,
The combination of the bladder, reaming out the exhaust together produce the increase. I am not certain how much comes from one or the other. It is a moot point anyway because plenty of folks get to the max rpms with tanks. Last weekend there were four tank flyers all at the limit.

The point I was making about the bladder is that it reduces the variables of a draw system and makes for a more reliable set up.

Incidentally I've never said they didn't increase power. I think I have often said just the opposite.

Now a question for you: why would you outlaw a cheaper, more reliable and simpler set up that happens to provide better performance?

Lou Melancon
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Post by montague »

Lou,
I'm not certain if you said it, but I KNOW it was stated many times that bladders don't increase performance. It sounds like that is false. If I have some time tomorrow, I'll go back through the old posts and find where this was claimed.

Oh, and as for being simpler, cheaper, and more reliable, what are you talking about? Bladders clearly aren't any of those.

- Tanks last forever, bladders have to be replaced every few rounds, so while a single bladder costs less than a single tank, I haven't spent a penny on tanks for my .15's after buying them 3 years ago. That's hundreds of rounds of combat on the same money. When was the last time you replaced a bladder? When was the last time I replaced a tank? The more you fly, the more money you save using tanks.
- I've never 0'ed a round because my tank suddenly exploded throwing fuel all over the place. Twice I've written down 0's on other guys score sheets because of a bladder. And more than once I've seen bladders fail and need replacement right before or during the 90 second window.
- While it's true that setting a needle value incorrectly on a tank can cause a loss of power, that's also true with bladders.
- With a tank, once I have it set right, I don't need to mess with the mixture setting, since I know the tank won't need to be replaced after the next round with a new tank that provides a slightly differnet fuel pressure.
- I've never had a tank shoot fuel in my eye from a few feet away as has happend with bladders. And I was just there to judge, it wasn't even my fuel.
- Tanks don't result in long threads on the forums about the color, thickness, and other traits of the contruction materal. You don't have to worry if you have the "right" tank material, and you won't find people discussing what tank material works best for them.
- Tanks don't require that you meet an experienced tank user in person to walk you through the proper starting and care and feeding procedures.
- Tanks don't have to be explained as "really, it's easiler than it looks" to newbies.

Do I really want to outlaw bladders? No, not really. I place highly at too many contests because of other guy's using them as it is. No reason to give away my advantage.

But I do think they discourage newbies. And I'm not terribly happy to now hear that they give a performance boost when it was stated in the past that they don't.

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Post by Which_way_is_up »

Jeez, lets get a life. I am so bloody sick and tired of listening to the same old rehash on bladders. [:(!]


Why don't we all just delete all the posts mentioning bladders and so we can leave this thread in positive and constructive way in which Lou put in all the work to make it?


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Post by Lou Melancon »

Kirk,
I won't argue with any of your logic other than to say more people are having problems getting their OS LAs to run than we should have.

This thread was created to give them a proven path to run on. Bladders were mentioned as a way to gain reliability and consistency, with the additional benefit of performance gains.

Too many folks expect their engines to run right out of the box and also tend to treat them the same as other types of engines they own. The results of doing this, in many cases, are bad. The OS .25FX is a wonderful engine. Almost anyone can get it to run right. Few other engines have this level of user friendliness.

I was at a SSC contest last weekend with 19 pilots. About 10 were having no trouble at all, the rest were either going lean or couldn't get a strong run. When you are having engine problems you get very frustrated, so I wanted to share what I had learned so that folks have better experiences.

In closing the reason for so many posts on bladders is that the people who run them are eager to provide information, insight, and help to those who don't. That is one of the great things about our community - folks share and try to help each other out. I know every post I have made on bladders is simply to offer knowledge for member consumption.

Lou Melancon
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Post by sgilkey »

YES YES, let the Ministry of Truth change all the previous posts to delete all the "trust us, bladders don't give a performance increase, they're just more reliable" posts. Winston Smith, where are you??? We can contract his services.

I applaud the helpful tone of the beginnings of this thread. However, there is simply no honest contradiction to the fact that bladders were debated ad nauseum in the formative days (wait, aren't they STILL formative??) of SSC, and we were told they were NOT an advantage (other than "more consistency"). Now we are told they clearly are (GASP)? I CAN ASSURE YOU, maybe only here in the in-bred and mentally/physically challenged frozen north, that bladders are a deterrent to newcomers. Even experienced competitors (admittedly we are "dextrously challenged" as someone pointed out previously) don't want to deal with them, a newbie, NO WAY.

I apologize for the cynical nature of my post, but sometimes I am just amazed.

Scott Gilkey
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Post by Lou Melancon »

Scott,
All of our newbies run bladders. They just work better. Yes, drilling out the muffler gives more rpms. You can relieve all its backpressure when you run a bladder. The bladder alone gives you some rpm increase, the drilled out muffler gives you the rest.

Your tone bothers me. It implies that some people are doing underhanded things. How much more open can anyone be than giving away freely all the information about bladders, fuels, break in processes, and needle settings voluntarily to help folks.

In many parts of the country we see a staunch refusal to try new ideas because they do not fit the old paradigms. We find folks criticizing things they haven't tried because they think it won't work or it appears to hard. I think we need to get out of our inbred gene pool and at least try new things especially ones that are easier, more reliable and can increase performance. Go ahead and shoot the messenger.

Lou Melancon
Alpharetta, Georgia
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