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Post  Yabby Sun Jun 02, 2024 8:59 am

Hi, i have been flying a coreflute trainer with an OS 15  in it. but its 5mm coreflute and a bit big and heavy and cant push through the bottom of manauveres. it flies, inside and outside loops, reverse wingovers, horizontal 8s and inverted, but its always on the edge of loose lines due to weight for the motor. Im looking at building a new one. smaller. less wing area. and rather than a wooden crutch to the tailplane a 6mm carbon fibre rod. im going to use 3.5mm coreflute and put two carbon fibre rods in the wing and a single wheel for take off. Any ideas on how best to attach the 6mm carbon fibre rod from the wing to the tailplane. The OS 15 performs well for what it is. 20% nitro, 7 x5 prop and 18,500 to 19k rpm. tried 8 x 4 prop and its a dog. lol.

any ideas and experience greatly appreciated

cheers,
Gary
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Post  Levent Suberk Sun Jun 02, 2024 10:03 am

Hi Gary, I think that small diameter screws and nuts are best for coreflute/coroplast material. There are special adhesives but they are pricey.
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Post  Ken Cook Sun Jun 02, 2024 10:35 am

Your using in my opinion too much nitro. This engine performs exceptionally well and probably better with 10% nitro. A 8x4 prop will turn most .15's into a real turd and I don't know why most insist on using them. In general, most older baffle .15's achieve their best power with light wood props in a 7x6. The OS LA will do far better turning even higher rpm's using a 7x4. I like the Master Airscrew for the LA .15 but they change the blade designs so much they're worthless to me because you essentially get a different design every so often. I probably have 6 different blade designs from Master Airscrew. The newer GF series will work but pending on what you get they can be very thin bladed and work better for paint stirrers.

If I may suggest, if your flying the maneuvers your telling us, why are you using a trainer? The problem is your plane and not the engine. A Sig Akromaster can fly rather well with the engine your using. It's not the engine designed for this plane but it can be easily modified to accommodate that engine. Due to having a large nose, it can be trimmed back. Weight is more important with a .15 size plane vs a .35 size plane. This is due to the engine weight and wing loading compared to the larger. This is why scaling down doesn't always work. Even a Akromaster needs a bit more wingspan and the materials used in building it are essentially the same as a .35 which equates to a turd on the end of the lines. The LA is heavy and it's almost twice as heavy as the engine that the Akromaster was designed to use. For high performance, a Jr Flite Streak can't be beat. However, a inexperienced pilot will have a Streak get away from them real fast. It will maneuver on itself not too mention the speed can also allow it to get ahead of them. The solution to this is to not turn and fly the plane out in front of them. I have flown a entire tank out in front of me and never turned once in the circle.

If I understand what your saying here is that your using that plastic cardboard stuff? You make no mention on your line length, your line material or the diameter of lines your flying on. The plastic cardboard stuff is going to mush out in the corners and this will ultimately feel like your flying a wet newspaper on the end of the lines. This is no surprise to me that your lines are going slack. If you can't maintain speed, your plane is not going to have line tension. I say this all the time, if your using rudder offset, engine offset, your plane is going to go slack in the maneuvers because your losing speed. Speed is the ONLY thing that provides line tension and nothing else. If your using the others to compensate, your hurting the performance of the plane. If the plane is too heavy, your stalling in the maneuvers, plane loses speed and ultimately you lose line tension.
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Post  Yabby Sun Jun 09, 2024 8:36 am

bought my 4 mm core flute today. got a 4mm carbon fibre tube for the leading edge, 3mm carbon fibre tube to slide through the middle of the wing. 7mm carbon fibre tube goes between the wing and the tailplane. found how to fix it on youtube. yay. 🤗
just gotta measure my current jigger up and work out the current cg. which is perfect, percentage reduction of plane and new cg and start assembling. nice bright orange. 😆 it will look great doing flat roundy roundy circles lol!
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Post  balogh Sun Jun 09, 2024 1:05 pm

Hi Gary

I am not sure if it helps bu this is how I fixed the tail on a 5mm dia. carbon fiber boom in my Lil SpeeDee

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I glued a 5x5 carbon rod on the top of the boom and fixed the horizontal stab on the rod..



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Post  Yabby Mon Jun 10, 2024 6:00 am

Hi Andras,

thanks for your suggestion. I like the way you have done it on Lil SpeeDee. Running the elevator control through the boom rod is a great idea. I hadnt considered doing that. I will see if I can also do that. though I dont think I can get the bellcrank in the required spot. Lil SpeeDee was what made me think of using a carbon fibre boom initially. strong and light. 🙂 Thumbs Up I Love This Forum!  I will glue mine in a similar manner. Very Happy
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Post  balogh Mon Jun 10, 2024 6:49 am


"I hadnt considered doing that. I will see if I can also do that. though I dont think I can get the bellcrank in the required spot. "

You do not have to run the boom in the full lenght of the fuselage. If it reaches the bellcrank, you can mount the crank facing the boom end and level with the boom centerline and you can run the pushrod inside the boom?

Gary, the standard black carbon pipe is prone to fibre spreading, it does not resist for long the torsional torque of the tail section, that tends to vibrate due to the soft carbon fibre boom..

I already changed out the original boom on the Lil SpeeDee with one, made of the same carbon pipe,  that was first treated internally by a thin layer of thin CA glue that I dripped into the tube on one end and rotated it along its inclined axis so that the glue, while flowing down on the tube wall by gravity, formed a spirally laid, internal coating, that, when cured, is very strong and added only 1 gram or so weight thanks to the CA glue. I helped the even spread of the glue on the pipe internal surface by pushing/pulling a bicycle spike with its bent mushroom end straightened as a plunger,  multiple times inside/along the full pipe length before the glue cured:

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Post  Yabby Mon Jun 10, 2024 7:22 am

thanks Andras. Thumbs Up those little tips from experience are gold sunny I can build starting off with the improved method. I am very keen to get very thin/light coreflute mixed with strong light carbon fibre rods. cheers
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