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  1. #26
    MJD's Avatar
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    RE: Shrike 40 with thinner airfoil

    What props does the K&B 7.5 seem to like? I have a couple I bought used but they seem well cared for, have not bench run them yet. I figured the 7.4" CF pylon props were about right.
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  2. #27
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    RE: Shrike 40 with thinner airfoil

    Any lower performance version of a high performance engine can be altered with a dremel and a carbide rotary file. Bring the exhaust timing up to 180 degrees and the intake closing to 60 degrees ATDC. this is what some folks in motor sports refer to as "Hot Rodding".
    I've seen very little of it being done in the model plane fraternity...except for the C/L Speed Club.
    If you really want to go fast... sometimes it takes a little bit of effort and risk.
    WHO GUNNA FEED MAW KEEEIDS..???

  3. #28
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    RE: Shrike 40 with thinner airfoil


    ORIGINAL: MJD


    Another option is to trim the APC 10-10 down to 9'' and clean up the tips, it has more hub strength. This is how the patterns for some of the CF 9-10 props are made. If this engine had ducted fan/marine timing I would be nervous, but as a pattern/strong sport engine I don't think it will spin a 9-10 much higher than 17-18k which should be okay. But your idea to test somewhere safe first is smart.

    Looking forward to your flight report!

    I cut down a 10x10 APC to a 9" leaving exactly the same tips shape (I did reduce also it's airfoil) , plenty more stiff than the original 9x10 APC as you said MJD , I'll use this one in case this engine really rev up. At this moment Im not sure how much rpm this engine can reach , before I bid on this one I sent a PM to other guy from here ( RCU) including a picture of the engine and ask him if the engine is the same than the one he has and wich he says is turning at 22k with 9x10 APC , he responded me yes is the same , he also gived me an input of how it runs, that was the reason I bought this engine.

    If this engine doesn't has the power Im looking for , Im willing to do some timing job ( if someone tells me ecxactly how to do it ) and after that still no enough power I think I'll look for a more powerful engine.

    Picture , from left to right ; original 10x10 , original 9x10 , modified 10x10 to 9x10 ( this one has also wider blades than the original 9x10).

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    Living on a War Zone !!!!!
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  4. #29
    SpeedBoy's Avatar
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    RE: Shrike 40 with thinner airfoil


    ORIGINAL: freakingfast

    I'm with MJD on this one. I think you'll be OK, but always do your run up with no one in the prop arc. After each flight, inspect the blade root/hub area for whitish marks and retire the prop if found. If you think the prop took a hit at landing, retire the prop.
    Thanks freakingfast I'll keep that on mind.
    Living on a War Zone !!!!!
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  5. #30
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    RE: Shrike 40 with thinner airfoil


    ORIGINAL: Speedy-Gonzales

    That SHRIKE looks awesome! How much ballast did you have to put in the back to hit your CG and what is your RTF weight?

    I love the SHRIKE and I am lucky to have 8 untouched kits of the 40 size and 4 of the Shrike 20 size kits.

    As Charlton Heston said at the NRA convention........'' You will have to pry them from my cold dead hands !''


    SPEEDY-GONZALES
    Thanks Speedy .

    I didn't add any ballast to hit my CG , I rather reinforce the stab and rudders with more wood and the battery is on the very rear. I moved back 1/4" the fire wall also.

    Total weight is 2.2 kg.

    What is the weight of yours Speddy ?. I bet mine is heavier than yours upss.
    Living on a War Zone !!!!!
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  6. #31

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    RE: Shrike 40 with thinner airfoil


    ORIGINAL: MJD

    What props does the K&B 7.5 seem to like? I have a couple I bought used but they seem well cared for, have not bench run them yet. I figured the 7.4'' CF pylon props were about right.
    I run vintage Rev-Up wood 8.75x6.5 on Powermaster 10/22 with a MC-9 plug on the 6.5's and on the 7.5's I use a Rev-Up wood 8.75x7. The old wood props just seem to spin up better on the old K/B's plus I can massage them for better preformance.

  7. #32

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    RE: Shrike 40 with thinner airfoil

    ORIGINAL: SpeedBoy


    Thanks Speedy .

    I didn't add any ballast to hit my CG , I rather reinforce the stab and rudders with more wood and the battery is on the very rear. I moved back 1/4'' the fire wall also.

    Total weight is 2.2 kg.

    What is the weight of yours Speddy ?. I bet mine is heavier than yours upss.
    Just a cow fart under 4 lbs RTF ( dry ) and that is with 2.5 ozs of lead to the very back of the fuselage and the battery also.

    My next SHRIKE will have a servo for each aileron out in each wing and I also plan on moving the firewall back some but the front spar is right there and makes for a tight fit for the tank. I may move the front spar back also. I also sandwich the main spar top and bottom with .014"x1/2" carbon strip. I wili also do away with the full length strip ailerons and and also inset them back from the wingtips 2". Fully sheet wings and rear surfaces. No open structure.

    Dropping down to a 2" spinner ( or less ) will be a substantial improvement and should reduce vibration by a bunch over the stock 2.5" spinner. I really like the improved look of your's with the 2" spinner.

    Speedy-Gonzales

  8. #33
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    RE: Shrike 40 with thinner airfoil

    ORIGINAL: SpeedBoy

    If this engine doesn't has the power Im looking for , Im willing to do some timing job ( if someone tells me ecxactly how to do it )


    The first thing you need is a fine tooth rotary file tool. You can use a Dremel motor or a die grinder to power the tool. The fine tooth gives you maximum control. Think of yourself as a dentist and the engine is your patient that you are operating on.
    The tool in the picture has a 1/8" diameter shank to fit directly into a Dremel motor.
    I also show a 1/4" adapter for when I use a full size die grinder with a 1/4" collet.
    You don't need a degree wheel to set the exhaust for 180 degrees because the prop drive washer can be scribe marked where it passes the casting marks on the crankcase. If your engine doesn't have distinct marks on the case that you can use for your 180 degree reference, then you can place your own marks on the case next to the drive washer..or make your own degree wheel.
    It is nice to have a strong LED flashlight to shine into the cylinder so that you will have no doubt when the exhaust port is opened and closed. Take a reading to see where the stock timing is at, then estimate how much material you need to remove from the upper edge of the exhaust port, but only remove a fraction of what your estimate is...then check the timing again. Make sure to deburr your cut before reassembly. You do not need to work the entire upper edge of the port, just cut it to form a "D" shape laying on it's side. You can grind the port slowly and recheck your progress as many times as you want. If you are afraid of accidentally going past 180 degrees, you can stop at 170-175 and then raise the liner with a shim to get the last few degrees. Piped engines can benefit from a slight lowering of compression anyway so it shouldn't slow the engine down if you raise the liner .002-.004" I like doing it like this because the liner height is another tuning tool to play with.
    There is most likely a good video about setting up a degree wheel on You Tube. It helps to have a metal bar that is bolted across the top of the liner. In the middle of the bar, thread it for a machine screw. Lower the machine screw just enough so that the piston taps it at TDC and this is your "positive stop" that helps you set the pointer on the degree wheel perfectly.
    Even a brand new engine has 5 degrees or so of "dwell" when the piston is at TDC or BDC because of the built in clearances in all the moving parts. This is why the "positive stop" bar is needed...it allows you to split the difference of the piston's dwell when you raise the piston up to the bar clockwise and counter-clockwise. These words will make more sense once you get your hands into the engine and see for yourself what is going on. If you enjoy learning new tricks, this is a rewarding project but it might be smart to practice on a less expensive engine that needs to have raised exhaust timing to really hit the pipe like a speed engine is supposed to.
    This mod kills torque, so you will never be able to turn sport sized props very well..you will be commited to little speed props and the engine simply will act like a tired dog if you cross the fine line of how much load it can handle. It is magical to see the engine get happy after shaving/scraping the blades, or trimming off some diameter, whatever it takes to find the invisible line that the engine can tolerate. Reducing the thickness of the blade's airfoil sometimes works, but remember that the airfoil provides strength...so be careful.
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  9. #34

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    RE: Shrike 40 with thinner airfoil

    CBP...thanks for showing us your "tool"! [&:]

    Have you read anything about putting hash marks in the intake, actually ruffing it up a bit that increases flow of air/fuel mix? Kinda like putting little impeller vanes in the I.D. of the crankshaft.

    There has been some experimentation with racing bikes and full size HP auto engines that has proven to be successful but in the cars and bikes they are doing it in the combustion chambers ( head ) .

  10. #35
    MJD's Avatar
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    RE: Shrike 40 with thinner airfoil


    ORIGINAL: SpeedBoy

    I cut down a 10x10 APC to a 9'' leaving exactly the same tips shape (I did reduce also it's airfoil) , plenty more stiff than the original 9x10 APC as you said MJD , I'll use this one in case this engine really rev up. At this moment Im not sure how much rpm this engine can reach , before I bid on this one I sent a PM to other guy from here ( RCU) including a picture of the engine and ask him if the engine is the same than the one he has and wich he says is turning at 22k with 9x10 APC , he responded me yes is the same , he also gived me an input of how it runs, that was the reason I bought this engine.
    I could be wrong about the engine, it might be capable of doing that rpm with the right pipe setup. Then again, if I had 25 cents for every exaggerated rpm claim on RC forums & classified ads I would own my own engine factory.

    I have several OPS Super .60 pattern engines, but no Piccos. The OPS is known for power too, but it won't turn 22k with a 9-10. 22k with a 9x10 is serious power - I would expect this maybe from a 10cc rear intake engine with ducted fan timing, large bore carb and proper pipe setup. But from a front intake pattern/sport engine? Maybe, I dunno. All I can say for sure is that if your Picco can do it, then you have a great engine there!
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  11. #36
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    RE: Shrike 40 with thinner airfoil

    Speedy, I used to hang out at Delphi Forums control line speed forum. Those guys are the real gurus who keep up with all the latest stuff. To them the airframe is 5% of the hobby..the engine is maybe 60% and the prop is all the rest. They are generous with their time and I always learn something after visiting them with questions.
    They're all a bunch of crazy SOBs..these are the guys who would stick a 180 mph .15 on a 100 sq inch piece of basswood, then spend the weekend in a cage trying to fly the little 1 pound model [that exerts about 50 pounds of pull].
    They're all machinists, metallurgists, experimenters, etc. carrying "the torch" for the late Bill Wisniewski, Clarence Lee, Duke Fox....[well some would argue that Fox wasn't as smart as he was good at perseverance until one of his crazy ideas actually hit pay dirt]
    WHO GUNNA FEED MAW KEEEIDS..???

  12. #37

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    RE: Shrike 40 with thinner airfoil

    my toy.os 40fsr.had a tuned pipe but they sound tested me at field and it didn't pass.anyone need an ops pipe and headers for os40 and for tt40pro?lol
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    what? i have to land?

  13. #38
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    RE: Shrike 40 with thinner airfoil

    I had the same problem when I visited a local field with a Jett .50 powered delta. He heard me do a short run-up in the pits and said I'd have to do a noise check before flying. I said "sure, I'll be right over", pulled off the pylon prop, bolted on a 9-7 (as I recall), richened the main needle about half a turn, and headed over for interrogation. Passed by a couple of dB.

    Just so you know, the regular members who were hanging around really wanted to see it go and said noise was a non-issue there. So I wasn't being a hooligan.. [8D]
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  14. #39
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    RE: Shrike 40 with thinner airfoil


    ORIGINAL: combatpigg



    The first thing you need is a fine tooth rotary file tool. You can use a Dremel motor or a die grinder to power the tool. The fine tooth gives you maximum control. Think of yourself as a dentist and the engine is your patient that you are operating on.
    The tool in the picture has a 1/8'' diameter shank to fit directly into a Dremel motor.
    I also show a 1/4'' adapter for when I use a full size die grinder with a 1/4'' collet.
    You don't need a degree wheel to set the exhaust for 180 degrees because the prop drive washer can be scribe marked where it passes the casting marks on the crankcase. If your engine doesn't have distinct marks on the case that you can use for your 180 degree reference, then you can place your own marks on the case next to the drive washer..or make your own degree wheel.
    It is nice to have a strong LED flashlight to shine into the cylinder so that you will have no doubt when the exhaust port is opened and closed. Take a reading to see where the stock timing is at, then estimate how much material you need to remove from the upper edge of the exhaust port, but only remove a fraction of what your estimate is...then check the timing again. Make sure to deburr your cut before reassembly. You do not need to work the entire upper edge of the port, just cut it to form a ''D'' shape laying on it's side. You can grind the port slowly and recheck your progress as many times as you want. If you are afraid of accidentally going past 180 degrees, you can stop at 170-175 and then raise the liner with a shim to get the last few degrees. Piped engines can benefit from a slight lowering of compression anyway so it shouldn't slow the engine down if you raise the liner .002-.004'' I like doing it like this because the liner height is another tuning tool to play with.
    There is most likely a good video about setting up a degree wheel on You Tube. It helps to have a metal bar that is bolted across the top of the liner. In the middle of the bar, thread it for a machine screw. Lower the machine screw just enough so that the piston taps it at TDC and this is your ''positive stop'' that helps you set the pointer on the degree wheel perfectly.
    Even a brand new engine has 5 degrees or so of ''dwell'' when the piston is at TDC or BDC because of the built in clearances in all the moving parts. This is why the ''positive stop'' bar is needed...it allows you to split the difference of the piston's dwell when you raise the piston up to the bar clockwise and counter-clockwise. These words will make more sense once you get your hands into the engine and see for yourself what is going on. If you enjoy learning new tricks, this is a rewarding project but it might be smart to practice on a less expensive engine that needs to have raised exhaust timing to really hit the pipe like a speed engine is supposed to.
    This mod kills torque, so you will never be able to turn sport sized props very well..you will be commited to little speed props and the engine simply will act like a tired dog if you cross the fine line of how much load it can handle. It is magical to see the engine get happy after shaving/scraping the blades, or trimming off some diameter, whatever it takes to find the invisible line that the engine can tolerate. Reducing the thickness of the blade's airfoil sometimes works, but remember that the airfoil provides strength...so be careful.

    Thanks for the explanation and the time you take for it combatpigg I really appreciate it .
    If necessary I'll start doing what you explained on a less expensive engine , 2 months ago I just raised .5 mm the exhaust port of a Rossi .53 but without any degree wheel , no too smart I think.

    I have read people (on many places) that know how to timming engines but not always willing to share it , nice to see you really want to helps others.Thanks again.

    Question: Do I need to touch the entrance ports also or just let them as they are??


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  15. #40
    combatpigg's Avatar
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    RE: Shrike 40 with thinner airfoil


    ORIGINAL: oly_rcer

    my toy.os 40fsr.had a tuned pipe but they sound tested me at field and it didn't pass.anyone need an ops pipe and headers for os40 and for tt40pro?lol
    You don't live that far from lots of privately owned open land. Even if you took out an ad on CL that said something like you would be happy to help out with hay work in exchange for flying rights...that would be preferable to paying dues at a club that looks down on high pitched noise [for whatever reason].
    I am blessed to have a land baron who doesn't mind me chasing the Hobos off his hay fields with my speed planes, but he's been trying to sell that land for the last 10 years or so so he can buy a South Pacific island..
    Introduce yourself to those who have lots of land that probably isn't earning them enough to pay for itself. It takes a lot of land to fly speedplanes comfortably, but there's all sorts of open fields to the south east of where you live.
    WHO GUNNA FEED MAW KEEEIDS..???

  16. #41
    combatpigg's Avatar
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    RE: Shrike 40 with thinner airfoil

    SpeedBoy, I'm very happy to help you in any way I can. You are obviously a very talented young man who will go on to great accomplishments. Just remember me someday once you become a corporate sponsored pilot for Futaba, Nova Rossi, etc...I'd like to be part of your crew.!
    The intake closing on front intake high rpm, limited load engines is set for 60 degrees ATDC....IIRC. Instead of taking my word for that, you would be better off going to the North American Speed Society website and find out where the forum is where all the control line speed gurus are hanging out. These guys keep good records about what all the winning combinations of speed mods that have already been done. I refer to their knowledge before working on anything that I don't know about.
    WHO GUNNA FEED MAW KEEEIDS..???

  17. #42

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    RE: Shrike 40 with thinner airfoil

    hiyas combatpigg,will have to see where you fly and fly with you sometime.anyhow i fly at flaming geyser park.great area and the ama club there has no dues.i have some places where i could open these up but even i thought it was loud,and that takes a lotwas well past legal limits for pretty much anywhere lol.besides,with the stock pipe i have a lot broader powerband for slow speed stuff and i don't need earplugs just to set the needle
    what? i have to land?

  18. #43

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    RE: Shrike 40 with thinner airfoil


    ORIGINAL: combatpigg

    ORIGINAL: SpeedBoy

    If this engine doesn't has the power Im looking for , Im willing to do some timing job ( if someone tells me ecxactly how to do it )


    The first thing you need is a fine tooth rotary file tool. You can use a Dremel motor or a die grinder to power the tool. The fine tooth gives you maximum control. Think of yourself as a dentist and the engine is your patient that you are operating on.
    The tool in the picture has a 1/8'' diameter shank to fit directly into a Dremel motor.
    I also show a 1/4'' adapter for when I use a full size die grinder with a 1/4'' collet.
    You don't need a degree wheel to set the exhaust for 180 degrees because the prop drive washer can be scribe marked where it passes the casting marks on the crankcase. If your engine doesn't have distinct marks on the case that you can use for your 180 degree reference, then you can place your own marks on the case next to the drive washer..or make your own degree wheel.
    It is nice to have a strong LED flashlight to shine into the cylinder so that you will have no doubt when the exhaust port is opened and closed. Take a reading to see where the stock timing is at, then estimate how much material you need to remove from the upper edge of the exhaust port, but only remove a fraction of what your estimate is...then check the timing again. Make sure to deburr your cut before reassembly. You do not need to work the entire upper edge of the port, just cut it to form a ''D'' shape laying on it's side. You can grind the port slowly and recheck your progress as many times as you want. If you are afraid of accidentally going past 180 degrees, you can stop at 170-175 and then raise the liner with a shim to get the last few degrees. Piped engines can benefit from a slight lowering of compression anyway so it shouldn't slow the engine down if you raise the liner .002-.004'' I like doing it like this because the liner height is another tuning tool to play with.
    There is most likely a good video about setting up a degree wheel on You Tube. It helps to have a metal bar that is bolted across the top of the liner. In the middle of the bar, thread it for a machine screw. Lower the machine screw just enough so that the piston taps it at TDC and this is your ''positive stop'' that helps you set the pointer on the degree wheel perfectly.
    Even a brand new engine has 5 degrees or so of ''dwell'' when the piston is at TDC or BDC because of the built in clearances in all the moving parts. This is why the ''positive stop'' bar is needed...it allows you to split the difference of the piston's dwell when you raise the piston up to the bar clockwise and counter-clockwise. These words will make more sense once you get your hands into the engine and see for yourself what is going on. If you enjoy learning new tricks, this is a rewarding project but it might be smart to practice on a less expensive engine that needs to have raised exhaust timing to really hit the pipe like a speed engine is supposed to.
    This mod kills torque, so you will never be able to turn sport sized props very well..you will be commited to little speed props and the engine simply will act like a tired dog if you cross the fine line of how much load it can handle. It is magical to see the engine get happy after shaving/scraping the blades, or trimming off some diameter, whatever it takes to find the invisible line that the engine can tolerate. Reducing the thickness of the blade's airfoil sometimes works, but remember that the airfoil provides strength...so be careful.

    As much as pig and i dont get along my engine guy and myself use much of the same techniques for modding engines. i think your 17,000 with the 10x7 is low and should be able to pull a bit more out with some work. the last engine i did was a Aviastar 53 from sig for 60 dollars. i set it up to run on the jett muffler and it would pull the 10x7 APC at the same 17,000. it took a bit of work to get it there. it took three engines to get it to this point. I would think you would have a a bit better flying plane with a jett 56LX and a 9x8 or 9x9 prop with the same speed as the 60 picco.

    open up the carb, put two chamfers on the case where the crank hole is near the carb, square off the corners of the crank fuel mix entry to help get more air flow, raise the exhaust timing slowly (5 degrees or .005") at a time. also look at widening the exhaust port also if narrow, look to get the squish down to .016-.022 range. the transfers like to be around .050 for every 10mm of stroke difference than the exhaust (lower) to match up well on the jett mufflers. now if you cant reach that number by raising the exhaust and going to go past 180 degrees then you need to lower the sleeve. do this by machining the sleeve down some of machine the case down. now with all of these cuts and machining you need to make sure you Do Not get any sub porting very bad on a tuned muffler/pipe set up. use a bright LED flashlight to check this as you go. a quick way to check crank timing is to use the four back plate bolts as a guide. The bolt holes are 180 out and usually the crank opens and closes on the bolt hole at 7 o clock and 1 o clock while looking at the crank pin. with any cut or machining you doing do it in small amounts then run the engine again to see where your at. DO NOT MAKE A BUNCH OF CUTS then run it until you gain experience. i am still new and modding engines only 5 yrs and still make mistakes lol. one thing on compression look at your oil color on the plane/test stand. Clear oil means the compression or nitro can be raised, light brown to brown is just about right. Brown to dark brown is to high or lower nitro. black is tearing the engine up. lol
    also there is 500-1000 rpm to be had in most of the grey APC props. look hard at the props under a good light and feel the "edges" with your fingers and you will see where to improve them.
    AMA # 126183
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  19. #44
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    RE: Shrike 40 with thinner airfoil


    ORIGINAL: airraptor

    also there is 500-1000 rpm to be had in most of the grey APC props. look hard at the props under a good light and feel the ''edges'' with your fingers and you will see where to improve them.
    Amen to that. I've been cleaning up APC prop edges for a while now in the belief it does at least some good and no harm. I usually end up wet sanding with very fine paper under a trickle of water. Only takes half a minute to make some tangible improvement in the feel of the LE and TE. Like you said under a magnifying glass the edges can look pretty funky, and it doesn't take an aero engineer to recognize they are not as friendly to high speed airflow as you probably think they should be.

    Production injection molding has it's limits when it comes to skinny edges. But in comparison to some popular sport wood props the airfoil quality on APC, MA and others is a tremendous improvement, rough edges or not. Some wood props look like a warped 2x6 in cross section as you get to the tip.
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  20. #45

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    RE: Shrike 40 with thinner airfoil

    I have worked some all the way to 12,000 grit paper under water and they looked pretty darned good. I didnt want to fly them.
    AMA # 126183
    Fly light, fly fast and fly low.

  21. #46
    combatpigg's Avatar
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    RE: Shrike 40 with thinner airfoil


    ORIGINAL: airraptor


    ORIGINAL: combatpigg

    ORIGINAL: SpeedBoy

    If this engine doesn't has the power Im looking for , Im willing to do some timing job ( if someone tells me ecxactly how to do it )


    The first thing you need is a fine tooth rotary file tool. You can use a Dremel motor or a die grinder to power the tool. The fine tooth gives you maximum control. Think of yourself as a dentist and the engine is your patient that you are operating on.
    The tool in the picture has a 1/8'' diameter shank to fit directly into a Dremel motor.
    I also show a 1/4'' adapter for when I use a full size die grinder with a 1/4'' collet.
    You don't need a degree wheel to set the exhaust for 180 degrees because the prop drive washer can be scribe marked where it passes the casting marks on the crankcase. If your engine doesn't have distinct marks on the case that you can use for your 180 degree reference, then you can place your own marks on the case next to the drive washer..or make your own degree wheel.
    It is nice to have a strong LED flashlight to shine into the cylinder so that you will have no doubt when the exhaust port is opened and closed. Take a reading to see where the stock timing is at, then estimate how much material you need to remove from the upper edge of the exhaust port, but only remove a fraction of what your estimate is...then check the timing again. Make sure to deburr your cut before reassembly. You do not need to work the entire upper edge of the port, just cut it to form a ''D'' shape laying on it's side. You can grind the port slowly and recheck your progress as many times as you want. If you are afraid of accidentally going past 180 degrees, you can stop at 170-175 and then raise the liner with a shim to get the last few degrees. Piped engines can benefit from a slight lowering of compression anyway so it shouldn't slow the engine down if you raise the liner .002-.004'' I like doing it like this because the liner height is another tuning tool to play with.
    There is most likely a good video about setting up a degree wheel on You Tube. It helps to have a metal bar that is bolted across the top of the liner. In the middle of the bar, thread it for a machine screw. Lower the machine screw just enough so that the piston taps it at TDC and this is your ''positive stop'' that helps you set the pointer on the degree wheel perfectly.
    Even a brand new engine has 5 degrees or so of ''dwell'' when the piston is at TDC or BDC because of the built in clearances in all the moving parts. This is why the ''positive stop'' bar is needed...it allows you to split the difference of the piston's dwell when you raise the piston up to the bar clockwise and counter-clockwise. These words will make more sense once you get your hands into the engine and see for yourself what is going on. If you enjoy learning new tricks, this is a rewarding project but it might be smart to practice on a less expensive engine that needs to have raised exhaust timing to really hit the pipe like a speed engine is supposed to.
    This mod kills torque, so you will never be able to turn sport sized props very well..you will be commited to little speed props and the engine simply will act like a tired dog if you cross the fine line of how much load it can handle. It is magical to see the engine get happy after shaving/scraping the blades, or trimming off some diameter, whatever it takes to find the invisible line that the engine can tolerate. Reducing the thickness of the blade's airfoil sometimes works, but remember that the airfoil provides strength...so be careful.
    one thing on compression look at your oil color on the plane/test stand. Clear oil means the compression or nitro can be raised, light brown to brown is just about right. Brown to dark brown is to high or lower nitro. black is tearing the engine up. lol
    +1..this is a basic indicator that model diesel guys use to set their engines and it applies to glow engines too.
    Stick your hand, or a piece of wood or metal near the exhaust and see what color the exhaust spray is.
    Amber is a great color for medium duty longevity...dark brown is for when you are trying to set a FAI speed record at any cost. Black is for the engine's funeral.
    WHO GUNNA FEED MAW KEEEIDS..???

  22. #47

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    RE: Shrike 40 with thinner airfoil

    after seening F5D airplanes these shirkes dimond dust and other's like it seem slow

  23. #48
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    RE: Shrike 40 with thinner airfoil


    ORIGINAL: zacharyR

    after seening F5D airplanes these shirkes dimond dust and other's like it seem slow
    Do you fly any of them yourself?

    These might be slower than most F5D models, but F5D are slower than F3S models (good ones anyway), and all of them are slow compared to DS gliders. Diamond Dusts, Shrikes, and other like it are low cost, low tech ways to fly fast and have fun while you're at it. They all have their place.

    A Shrike is by no means an optimum airframe for speed. It is just a fun airframe to overpower and make faster. Deltas the same deal. A $75.00 delta kit plus a $129.95 glow engine can go over 130mph and fly for 5 minutes at full throttle on a buck of fuel. Or put a hotter .50 on one and do 170 for 3-4 minutes.
    Sorry I'm late dear, I had to help my uncle Jack off his horse.

  24. #49
    combatpigg's Avatar
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    RE: Shrike 40 with thinner airfoil

    I knew a couple of guys back in the 1970s who ran AA / Gas [8.60s at 170 mph] and they got bored with those cars..

    One guy moved up to Alcohol Funny Car...the other guy converted his rig to a AA / Fuel Altered.
    Both guys eventually got tired of the insane cost and work it took to campaign the quicker cars and they left the sport.

    OTOH I have known a 3rd guy all these years who has always enjoyed running much slower, less expensive cars and is still at it, hitting every drag strip and major event he can manage to get to with his "lowly" 11-12 second car.

    So..my advice to the guy who thinks the planes featured at this forum look slow is to avoid building and flying any of these planes if you get bored that quickly.
    WHO GUNNA FEED MAW KEEEIDS..???

  25. #50

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    RE: Shrike 40 with thinner airfoil


    ORIGINAL: zacharyR

    after seening F5D airplanes these shirkes dimond dust and other's like it seem slow

    yes maybe but this is mostly about guys making a normal plane faster. speed is different for everyone.
    I worked hard to get a TD.010 powered plane to hit 45mph it looked like it was hauling the mail with only 52 square inces of wing. It was a rush to fly now it wasnt fast compaired to many other planes but it was fast and fun to me! I have a F-5D plane also with a old nelson rear exhaust for it. it should pull around 210-215 with it. i bet it would be just as fun as the little TD.010 powered plane.
    AMA # 126183
    Fly light, fly fast and fly low.


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