highflyinguy

Guys ,We need some more posts about engines and planes.
Right now I am flying a new Barnstormer with an OS .25LA. The plane flies great but the engine is not prefoming to good, even after following Mike Pratt's suggestions on Stukas forum.

I saw him fly at the contest lasy year in Denver, with his Primary Force and OS.25LA. I wish I was flying the LA then so I could have tapped his knowledge as to what I was doing wrong.

Anyone have any experience with one of the little beasts?
Thanks, Jerry

highflyinguy

Silly me, I fogot the paticulars about how I have the engine set up.
1- .250 ventui from Stuka
2- Uniflow metal tank, non pressurised
3- Sig 10%N 20% 1/2 1/2 Lub, boosted to 22% with castor.
4- Supre Tigre style N/V
5- Thunderbolt R/C plug

I get no cosistant runs, it idels at 10, 000 RPM just breaking from 2 to 4 cycle.

Sometime, after a loop the RPM drops and stay so low the plane can barly fly the rest of the flight.
Sometimes she runs a whole tankfull at a wet 2 cycle.
Sometimes it plain stops no matter what the plane is doing, flying level, wing over or loop.
It's driving me more crazier, than my present level of crazyness.
Any suggestion would be appreciated.
Thanks Again, Jerry

tperry2054

My Feedback: (15)

Jerry,

Sounds like either a fuel problem or possibly a leak in the backplate crankcase seal. You didn't say whether you are using the remote NVA or not. They can be made to work ok but have been a pain in the rear for some. After the usual fuel check like bubbles in the line, boogers in the NVA etc. I would definately check out the backplate seal. Wait you might ask! how can crap in the lines make it run slower? It just may be in there when you start the engine and then clear itself resulting in an over rich slow run. If your run is slow because it leans out that is a different matter. A 25 FP back cover may be the solution as some people have problems keeping a seal on the plastic one. The 20 FP cover should also fit. I don't have any extra back covers now or I would send you one. If Dan Rutherford sees this message maybe he has a spare.

Just remember to only try one solution at a time 'til you solve the problem. I think part of your problem is you're an olde Fhart like me and time is more precious than it was when we were younger.

Tom Perry

PS keep us informed

gcb

From reading the threads on SSW, you might want to try running a steady two using a 9x4 or 10x4 prop and a stock muffler. Sounds like you are shooting for a 2-4 run and I don't think that engine will do it successfully.
From the venturi/needle assembly, I would assume you converted the engine from throttle. Many use the stock OS CL setup successfully also.
That said, the only LA I have is a .15.
Have you asked Len?

George

dadamisin

Hmmm, my experience with the LA 25 comes in RC trim but I would second the suggestion that you use the 9-4 prop for starters and let it wind up a little - you should get around 11,250 or so. The RPM's will not hurt it - keep it a little off peak and it should not run hot.

The oil content looks too high. I'm using 10% Wildcat which has 18% Klotz/castor blend. Sig at 20% is already pretty sloppy and extra 2% castor .... I just do not think that is doing anything FOR you, and could probably be dousing the plug and just generally getting in the way.

I'd say first task is to seek a full CONSISTANT run, then start propping up - probably a 10-4 PowerPoint or 9-6 PowerPoint would be the practical limits, RPM's will drop some but try to get the same kind of run - probably a very fast 4-cycle or "sloppy" 2 cycle run.

Dennis A

highflyinguy

Tom and George, Man I am having a senior moment, forgot some important stuff.

I am using an APC 9x4 going for a 2 cycle run. The engine was not R/C, I removed the remote N/V and put in the Super Tigre look alike N/V also from Stuka. I wish I had gone with the OS forward mounted N/V like on the 40 & 46, but I was trying to be like Mikie. No going back since the case is drill out for the ST spray bar.

I did reseal the plastic back plate with a heat resistant silicon that I read about on another forum post. I am thinking of getting a metal back plate, gasket set and socket head screw set, from Tower Hobbies, they have them left from the Tower or OS 25 fp's.

I use the stock muffler and have tried it with and without the baffel, but not with muffler pressure.

Another point is that I fly at 5000' altutude, but so did Mike Pratt when his engine ran great.

Tom, I think you set me on to something, my fuel is gettin on in age, from early this year, when I broke in my OS40 and 46 LA's which ran fine. Havent used that fuel since. Right idea, doing one thing at a time, getting a new jug of fuel for this week end.

My employer anounced two weeks ago that they were shutting down the plant where I have worked for 26 years, permenantly, I have two more years till early SS, so I was tring to use all the old fuel I had first, but a guys gotta do what a guys gotta do, unimployment fuel.
Thanks for the brain jump start, Jerry

highflyinguy

Dennis, Thanks for the reply. As per my last post, I am going to get some new fuel. don't know if I can find Wildcat, but I'll try. If not, I will get some Sig 20% and not boost the oil content.
Next step if I can't get good results is to put one of my old Fox .35's in the Barnstormer, I know they run well.
Thanks, Jerry

dadamisin

...actually a Fox 35 in a Barnstormer is about as good as it gets, isn't it? I am just hoping you can steady out the run on the LA because that would at least prove you do not have tank problems.

BTW I do not remember the rest of the posts, but have you checked for leaks in the fuel lines? filters? Muffler pressure lines? Those can all cause a multitude of problems.

da

highflyinguy

Dennis, I have checked the tank for leaks, no leaks noticed and replaced the supply line and capped vent.

I washed out the tank with acetone first and then alcohol, then fuel.

I have not tried running on pressue from the stock muffler, I'll give that a try hoppfully Sunday.

Thanks again for more brain food, Jerry

Ya know, mabe I'll just will re tink and renew my membership to PAMPA, I learned a damn lot of stuff from the Stunt News and individual members. I appreciate your reply on that post about me quitting. I rember a couple years ago, Brett Buck talked me thru some bad engine runs on my Silver Fox 40 and flying at high altitudes. I think it may be best to renew to help support the news letter, C/L flying and keeping in touch with people like you and Brett and TPerry. Wish I had more flyers in my area, Rusty Brown lives 60 miles North of me, Iv'e met him a few times, great old guy who learned to fly in my home town, Longmont, Colorado about 40 years ago.

dadamisin

Hmm, I did not see you mention fuel filter - I certainly hope you have one! I speak from expreience when I say that a leaking filter is bad news!

Other possible sources of leaks: does the venturi have a gasket? Is the gasket seated? Is there a leak path between the venturi and the crankcase? that can ruin your whole day too! My brother was fighting a losing battle with an old Veco 35 until he discover that leak. He then glued the venturi into the case using silicone and the problem went qway. Ditto the NV assembly - make sure it is not leaking around its base.

Took me a long time to reach this point but I have become a believer in muffler pressure - I think it could have a positive impact for your situation.

Don't be afraid of changing glow plugs either. My favorite continues to be the K&B with Fox a close second.

Having said all that I have, I cannot claim to be any kind of expert on high-altitude engine problems. To me every engine problem usually boils down to the engine getting fuel, air, and fire. If the engine is sound it MUST run....

dennis a

highflyinguy

I replaced the fuel filter twice.
Checking the venturi "O" ring and sealing on the N/V assy. is next on the list, thanks for your reminder.
I will also try muffler pressure. I have never run an engine on pressure, but this might be the ticket for the LA engine.
One thing I did notice since installing the ST N/V assy. is that I get good 2-4-2 (more 2 than 4) at 10,300 RPM, with the needle only 1 turn out from being closed, but it will not start again unless I turn it 2 turns open and then close it down to about 1 turn to get good setting for flying. Seems like only 1 turn open is very unusual.
Jerry

tperry2054

My Feedback: (15)

Jerry,

The fact that your engine runs as you say makes me think there is something amiss with the needle valve. Have you taken the needle all the way out and checked for a piece of debris that may be keeping the needle from seating properly? I usually start with at least 3 or 4 full turns open and have never seen the need to go to one turn from being fully closed and work right. This might also explain your previous inconsistant runs. Have you a spare NVA from another engine to try? If nothing else try removing the lock down nut completely and see if the needle will then go in a little farther. Please keep in mind that not being able to see the engine and trying to give advice is frustrating too. Buddy, I sure wish I had the answer for you. You may be fighting more than one problem but I'm pretty sure there is something wrong in The NVA area.

Tight lines,

Tom

dadamisin

Gotta agree with Tom(?) about the NV assy or rather the total system. Only turn open sounds too tight, I would normally expect 2-2.5 turns for a "normal" setting. The other wildcard is that you have to change the setting - drastically - between starting and running. That just should not be required.

* What direction is the spray bar hole pointing? It ought to be pretty close to straight down, parallel to the axis of the venturi.

* Leaks under the venturi (ineffective gasket) or around the base of the NV assy letting air bypass the venturi could concievably lead you to open the needle for starting - but that seems a stretch.

* I think you should (and you probably already have tried this) also try removing the NV completely and pass a fine wire through the spray bar. A piece of debris could keep the needle from closing all the way and also cause erratic settings. Could also be a burr in there from the spray bar hole.

All else fails try replacing the NV assy...

Dennis A

highflyinguy

Tom, Yes I did clean out the N/V assy.

However I have always suspected that when I ordered the custom ventui and ST N/V assy from Stuka, that perhaps he sent the wrong size N/V. I have never seen anyone else's OS25LA.

The one he sent looks like the same one that would fit My OS 40fp, OS40LA and OS46LA.

I don't know what size ST type N/V assy might be avaliabe for the 25LA or if the one I have was also ment for the .25LA. I made it clear to Lenard what I was doing when I ordered the .250 venturi.
Jerry

highflyinguy

Latest hot find.
When I went to check out the needle valve assy that I got from Stuka, I found the "O" ring on the venturi was way too small in diameter and thickness. I replaced it with the one from the original OS venturi and checked out the spray bar which was clean and burr free. I then sealed the spray bar on both sides with Blue RTV silicone, set it down from 90 degrees, about 4:00, to the rear.

I think I may have found somthing important that was definetley wrong.

Ya know , I hope other newcomers lurking at this post, learn some things on engines and what great guys you are to help a feeble retread from the 50's. I wish I had named the post diffrently, but I was just trying to drum up some action from the members to post something.
Jerry

highflyinguy

After all the help from you guys, today I had not only great engine runs but got to know the Barnstormer.
I even got it going so good, I was able to play with diffrent props, best overall for my needs is an APC 9x5.
I think there were a bunch of minor things I fixed from your suggestions, but I'd bet it was the wrong "O" ring for sealing the venturi causing most of my problems.
Thanks men for all the help, Jerry

tperry2054

My Feedback: (15)

Jerry,

Some people bang their head against the wall, some fix model planes. The results are just a little different. In both instances it feels a lot better when it's over, but the plane fixer has something to show for it besides dents in the wall.

Tight lines,

Tom

dadamisin

Whoo Hoo that's terrific news! You really worked your tail off to get that bird running and flying right, so to the victor the spoils. Glad its going to work out.

BTW, I am kinda new to the RCU, does this mean the END of this forum topic???

da

Old Sourdough

Only if no one else replies, or asks a different question.

highflyinguy

Dennis, Check Tperrys post "Jerry Bohn's Barnstormer" post for some final settings and testing that worked great, at least for me and my hiflyin altitude, which is the same as when Mike Pratt posted his experience with the OS.25LA.
Thank you for the input, seems like evrybodys help got the engine to a great run. Minor tweeking is sure to follow.

Tight lines and I just rejoined PAMPA, thanks for the encouragement for that too.
Jerry

dadamisin

I think I helped brainstorming but all the credit goes to you for doing all the hard work. and bringin that LA under control - sounds like you are off and running, uh that is flying, now!

Now I need help - am spending TOO MUCH time at work and not enough time building and flying - got any ideas??? ;-)

da

highflyinguy

Dennis, Arrange for your workplace to close its doors, as happened to me last week, but if yor married dont tell the Mrs. right away. That will by some time. Then go apply for unemployment and wait. Guess what you can do for 6 weeks while waiting for the first check. Not a brilliant plan but it's mine and working.
My flying buddy just works on his planes about 2 hrs every other night religiously and seems to get enough plane built and flys only one weekend day per week. He is happy with that.
Good Luck, Jerry

airbatic

Ha ha! More posts to an already boring subject of control line flying. Add radio and fly, fly, fly. You feel as great as I am.

Kraus

Fix-it

My Feedback: (3)

Typical retort from a non C/L flier. To us that know the feeling of "Direct Connection" no explanation is necessary, to those who don't no explanation is possible.

mclintock

My Feedback: (3)

It's funny to me that the hottest latest thing in mainstream RC is honing one's skills at keeping the plane hanging perfectly still. (hovering-zzzzzzz)[sm=sleeping.gif]

sorry for the irrelevent OT