OS LA .15 Set up and Reliability

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

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Dawg
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Post by Dawg »

Here is the link to the FP Backplate in Tower
LXCF83 O.S. Cover Plate .15 FP/S http://www2.towerhobbies.com/cgi-bin/wt ... LXCF83&P=K
I use them and have not had any problems with the backplate coming loose since.

David McGinnis
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Post by lightning »

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">.......I use them and have not had any problems with the backplate coming loose since.

David McGinnis
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David, did you notice an RPM reduction with the FP backplate?
And did you use a a gasket, RTV or just lap it to the crankcase??
Thanks -
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Lou Melancon
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Post by Lou Melancon »

Keith,
Don Pruitt and I took an OS LA .15 and ran it first with a black plastic backplate then put an aluminum one on it. The aluminum backplate dropped 200rpms on 10% PowerMaster fuel on a cool humid morning.

Lou Melancon
Alpharetta, Georgia
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Post by Dawg »

I agree with Lou, it was about 200 RPMs difference. But for the most part, that is no big deal since we have to detune to stay under 17,500 most of the time anyway.
I use the FP gasket and gasket sealer with Lock-Tite in the screws. I checked all 5 of my engines last night and they are all rock solid. No leaks and the screws still tight. Not one loose screw. With the plastic back plates, I <u>always</u> had to reseal after each day of flying.

David McGinnis
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LARRY
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Post by LARRY »

I also tried the two backplates with the same results as Lou and David, 200-300 rpm differance...I have found a new method that works great for me, i use the stock backplate and seal it with plumbers teflon tape, one full tight wrap and then use red locktight on the screws...so far no problems or screws coming loose and best of all no leaks...The red gasket sealer we were using works fine but will not hold up for long and i was having to re-seal after every other event.
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Which_way_is_up
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Post by Which_way_is_up »

Larry,

The tape sounds interesting but I'm not sure that I fully understand how you apply the tape. It may not be possible but if you could take a picture of the way the tape is applied it would be nice. [:)]

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Post by sgilkey »

The need to needle the 15Fp slowly is not related to the RNV, this applies even to standard NV on the carb. I have no explanation for why the 15FP, RNV or not, behaves differently than the 25FX with an RNV. I have seen several folks have fits with poor power and over-lean in-air performance, and when i show them the S-L-O-W needleing technique, it really helps. Several of us locally are running the FP- have not had much experience with the LA to say if it applies there as well. But my Magnum 15XL does not do it.

I did some testing on fuels and glow plugs and will post results when i get some time to put them in presentable format. In our area, we cannot consistently hit 17.5k so are always looking for ways to get a few more rpm. on good days with ideal temp/humidity we might exceed 17.5, but usually not, so I tried some experimenting with plugs and fuel. Until i get around to posting the details, the bottom line was the K&B std long plug and Powermaster fuel did best- this on an FP.

Scott Gilkey
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Post by LARRY »

My Teflon tape idea works well, the mehtod i use is to wrap the teflon tape as you would around pipe thread, i only use maximum two rounds (flat) around the area between the crank case and the long part of the backplate so that there is a seal between the two, some of the tape will push itself around the flang area for a perfect seat when you twist the backplate into the crank. start your wrap around the backplate (im left handed so mine is counter clockwise) then twist the backplate into the crankcase in the opposite direction so that the tape does not unwind,you may see some of the tape in the mounting holes, just coat screws with red locktight and push through...i will try and get Lou to post a pic of this soon.
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Post by LARRY »

Scott...Lou's method of the LA15 break-in works if you take the time to do it..however, i use a blend that most do not use, Lou as my witness has seen one of my LA's turn 19 plus and another turn 18700 on any given day...the LA engines that i did not break-in using Lou's method will only turn 17500 to 17800 on a good day.. The only thing i do differant than Lou is i use RedMax 15%nitro and 18% all Castor break in fuel for the first three 4oz tanks, then i switch to RedMax or magnum 15% all synthetic blend with NO CASTOR from then on..Most of the problems that ive seen all relate to air leaks from backplates or bubbles in the fuel tank....just my 02 for you. Larry
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Which_way_is_up
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Post by Which_way_is_up »

Larry,

Thanks for the follow up, I understand now what you're doing with the tape. [:D]

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Ben Morrow
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Post by Ben Morrow »

HEY GUY'S !!!!!!!!!![:D] Whats up???

Lou, I Just linked over to check out your Bladder write-up. GREAT work! As an old Bladder guy from the old day's, I can see where this should help a lot of folks out "Big Time!" Great article, enjoyed the reading. As for the performance questions, I do kinda feel that bladders are better to run just for the reason of bubbles and not bothering with a clunk all hung up in the rear of the tank (Shaking a plane like crazy to get it loose![:(!]) You guy's all know what I'm talking about on the clunk. The power of a pressure system don't really amount to a hill of beans until you open up the intake, open the exhaust and tune her in with a good steady needle setting, and the glow plug that your set-up likes. A little on the rich side for me at launch seems to be my favor.(Same as a tank) Anyway, Great write-up and just droping in to say hea and good job!! Bladders are great, but a plan ole tank will win a contest to. It's just pretty much up to what the pilot feels good with.[:D]

Gone again![:D]


Ben Morrow AKA "Hillbilly"
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Post by Lou Melancon »

Hi Ben,
This thread started out to provide information on how to get the OS LA .15 set up and to run reliably. Things like oil content, needle valve setting, and break in are more important than whether you use a bladder or a tank, but it got sidetracked.

At a recent contest I saw both sides of the SSC engine issue: those having no problems at all and those who were really hurting. The purpose of this thread was to freely to give all who had interest or need some information to consider.

The thing I see the most is engines that go lean in flight, lose power, heat up, and lose the piston to cylinder fit. That is why I wrote the part about how to set the needle valve. Some folks may just get something worthwhile out of trying it.

Lou Melancon
Alpharetta, Georgia
Ben Morrow
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Post by Ben Morrow »

Lou,
If they want to run a bladder, Then if they read this thread, ALL will have a good spot to go to for the info needed! Again, GREAT JOB!!

Ben Morrow AKA "Hillbilly"
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"Furballs" are for me!
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Post by Don Pruitt »

<font face="Arial">Lou,
As per my normal practice, I have to try every permutation of how to get it wrong before I ever finally find something that works. What do you use to seal the back plate on an LA 15? I am sitting here looking at six different tubes of crap that doesn’t give me the desired result.

Example 1 - Locktite Thread Locker Blue. Glues the back plate on and you have to tear up the backplate in order to get it back off.

Example 2 - Permatex Thread Locker Blue. Same as Locktite, glues the back plate on permanently.

Example 3 - Goop, Outdoor contact adhesive and sealant. Sets up very quickly and doesn’t stick to aluminum very well. Doesn’t seal.

Example 4 - Locktite Tite’n for bolts. Not for use on plastic.

Example 5 - Permatex Form-A Gasket sealant formulation 2B. Doesn’t seal. I don’t know where it goes but after you seal the back plate and it still leaks and you remove the backplate it is gone. It must be dissolved by the fuel/nitro.

Example 6 - Permatex Hylomar HPF Gasket dressing and flange sealant. Never sets up or hardens. Similar to axle grease.

I am thinking about trying Tanglefoot next.
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Don Pruitt
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Post by Lou Melancon »

Don,
For most folks the TangleFoot works best on the leading edge rather than the backplate. If you try it let us know how it works out.

The stuff I use on the plastic backplate is RTV High Temp Silicon. It is red or orange in color. I put it around the backplate so that when put it into the case it forms a seal around the backplate. I also put some in the bolt holes to help it hold the screws in place.

One thing I have not tried but mean to is to find an O-ring that will go around the backplate and seal against the case. The ACE Hardware store has boxes of O-rings, but truthfully since I started using the metal FP backplates I haven't had any more trouble with backplates leaking.

Lou Melancon
Alpharetta, Georgia
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