"1/2 A" & "1/8 A" airplanes These are the small ones...more popular now than ever.

Ap 15 great engine

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Old 05-24-2014, 04:24 PM
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airraptor
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Default Ap 15 great engine

Tried a used Ap 15 today. Opened carb up to .190 removed one head shim down to .018 squish and open exhaust. It turned a MA 8x3 combat prop at 18,100 on 5% fuel and turned 19,500 on 30% fuel. Darn good little engine much stronger than CVA's and conquest engines. Pretty light also.
oh and it's really a .13 not a .15...
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Old 05-24-2014, 07:34 PM
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Looks like that engine likes the 30.percent nitro.
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Old 05-24-2014, 07:59 PM
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yes it did. Even 18,000 on 5% is pretty good.
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Old 05-25-2014, 05:46 AM
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I made a turbo plug head, and it went another 1900 rpm better too. I didn't try the 8-3 in my tests, I used a 7-5. It didn't keep up with my Conquest, but did quite well for a $30 motor. I have not tried 30% yet, I just use 10 all the time. I have 2 now, and the second one seems to have a fair bit of slop in the liner to crankcase joint. I haven't run it yet, it is just a spare, but I hope that doesn't slow it down. It is a very light motor too being based on the .09. Pics show a carb, needle valve, header for a pipe and a larger stinger I made up for the muffler. The old stinger can be unscrewed easier. I made the hole 6mm just because that is the min. size for F2D combat, not that it would be competitive or anything. The 4mm was just too small for a .15
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Old 05-25-2014, 08:14 AM
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The MA 8x3 combat prop and the APC7x5 are very close to the same load. Yes the exhaust is very restrictive on these things. It really needs the next size up thread size to better match the exhaust. Also FYI the FP series of NVs will screw right in that carb.
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Old 06-17-2014, 04:32 PM
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A Rap........is there any way to make this little gem an R/C engine? I have a couple of apps for it.
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Old 06-17-2014, 04:39 PM
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Most of them are r/c, I converted mine over to control line. The .09 pictured has the carb used. Kind of a so so carb. A Rap-I think I checked an 8-3 prop on a .15, and it revved a little higher than the 7-5 I had. Pretty close though.
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Old 06-17-2014, 06:28 PM
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After checking I see that they do make an R/C model. Any word on it's performance?
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Old 06-18-2014, 04:53 AM
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Well, since I seem to be the only person in the world to have tested one of these, 13,300 rpm with a 7-5 MA GF series 3 prop, 10% fuel with muffler, 15,700 with no muffler, 17,200 with an opened venturi to .240". I made a Turbo plug head and with the opened up muffler it went 17,100. That is almost as good as the OS LA at 17,400 with no muffler. The LA is really quite a good motor for what it is. It idles better too. The AP .15 is a bit smaller than a .15, working out to a .135 or so. It is made from the .09 case, so the crank hole is small, as is the muffler and carb. The AP .09 is really pretty good, but the .15 suffers a bit. Having said that, it is a fairly small and light motor that gives a bit more power to a smaller plane. The ASP .15 is almost 2 oz. heavier, but puts out 17,600 rpm with no muffler for maybe $45. I found it easier to get some performance gains from the ASP compared to the LA if that is what you like to play with. The LA is more money as well, but more consistent in quality control. Oh, and the Fora puts out 20,500 rpm on the same prop, I could match that with a Turbo head I made up on the ASP. Hard on plugs though.
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Old 06-18-2014, 06:17 PM
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I have five of them and since I started this thread your not the only one aspeed....

a few minor mods and it performs well. i am working on a header of it to test soon. they are 29 dollars from hobby king Steve
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Old 06-19-2014, 05:59 AM
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How about the idle? I've seen numerous Magnum engines with very strong top ends but were impossible to adjust for a reliable idle. I've been wondering about the AP brand.

Thanks!
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Old 06-19-2014, 06:32 AM
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I think the combat guys fly this engine but not 100% on that. The magnums seem to idle fine to me but I dont idle around much...
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Old 06-19-2014, 06:36 AM
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I found it didn't idle very low, so I drilled an air bleed hole in it. It seemed to work better and would tick over real slow. Next time I tried it, it didn't work so good, after I opened up the hole in the carb a bit. The .09 one is ok, nothing great, it stumbles a bit on acceleration. Probably go low enough to land or do a touch and go. I have since bought another .15, but have not run it yet. There is a very loose fit between the liner and case, so it may not be a real great one if there is any leakage between the exh and intake ports. I want to try the new carb on the old motor just to check the idle, but the motor is in a combat plane, and I don't want to disturb it. The new on I want to keep new for a while. Airraptor, I bought a die for the thread and made my own header on the lathe. I think the die was only $15 or something. It is a standard fine thread metric die. M10 x 1 or something. I showed it on the picture above. I gave it away to a guy that bought a Turbo head from me, but can make more. I was going to try a pipe, but found that the rod wears a bit fast at 25,000 rpm, so I aborted that idea.

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Old 06-19-2014, 07:51 AM
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Yes the rod is the weak part but that is fixable so that it never wears out.
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