AP.15 Yellow Jacket
07-27-2007, 03:18 PM
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AP.15 Yellow Jacket
I just got my new AP.15 no directions Does anyone know what size prop to use to break it in and once broken in. What fuel % fuel to break it in I have the 20 percent heli which I think has 20 percent oil, but senthetic. If this fuel is ok to break it in how many ounces of castor to a gallon.
07-27-2007, 04:12 PM
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RE: AP.15 Yellow Jacket
At a guess, try an 8x4 or 8x3. I'm assuming the engine is an ABC type[or a variation on that theme such as ABN] Its geneaology appears to be along the CS or 3-Leaf/SY brands of Chinese racing engines that appeared in the 90's and 80's respectively, but with a conventional glowplug head rather than a button. Certainly the design of the 09 and 15 suggest a relationship.
The quality seems to be variable. The first thing I would do is remove the backplate (it should have an O-ring seal and be quite easy to unscrew if its like its predecessors) and check for machining swarf in the crankcase. If there is any remove it obviously! [and it would do no harm to swab out the crankshaft bore with a cotton bud while you're at it].
AS for fuel-your 20% heli mix is as much nitro as you should consider using at this stage-a bit less (10% nitro) would be better. Oil wise I would add 5 oz of castor per gallon for a safety factor. Once run in it may be OK on all synthetic [but as you should know from this and other forums] there is a greater risk of doing damage during a lean run with an all synthetic mix-and an accompanying engine life issue. You will get a little bit more power on an all synthetic mix compared to an all castor mix with the same nitro %.
If your local environment permits it (your call obviously!) I would remove the muffler for running in. The mufflers on these APs are ridiculously small and restrictive-and will certainly cost you a lot of power -but then you are faced with what to replace them with in regular use! The accepted wisdom for running in ABC type motors (where the design fits are such that the piston cylinder clearance is optimum when the engine is running, and normally 'tight' when the engine is cold) is for short, slightly rich (not blubbering rich) runs of say 2 mins at a time, and lean the engine out to peak for 20-30 secs before backing off rich again, allow to cool down completely, then repeat the process. Again many factors such as the exact metallurgy, the amount of cylinder taper, and the quality of the machining influence the process-but 20 mins accumulated in 2 min runs might well see it fully run in. As a generalisation ABC type setups require less running in time than ferrous metallurgies. The key to the process is bringing the engine up to normal 'peaked' running temperature for short periods, and this is critical to achieving the optimum cylinder fit during the running in process. Running in the old 'ferrous' way-slow, and rich-if done on an ABC motor, will wear it out before running it in! [the engine doesn't get hot enough for the liner to expand appropriately, the piston fit remains tight, wears in, and eventually is too loose when the engine IS at normal peaked running temperature!]
Obviously, wire or fix the throttle at full open during running in, then once the engine is properly bedded down, then you can start fiddling with the throttle idle adjustments. You never know-they may even have set it right at the factory!
One final thing-it is worth experimenting with different glowplug brands and heats-though the good old OS #8 you mentioned previously is as good a place to start as any! The benefit can be as much as 1000 rpm (or a better idle).
I'm guessing that as a ball raced engine, with a possible racing background to the design, the engine will probably want to rev reasonably high and peak perhaps at 16,000-17,000. Even if it is only average in power output-say 0.3-0.4 BHP, this would likely suggest that your usable prop range would be from 8"-7" diameter, and pitches from 4"-6". 9" props are likely to load the engine down to much. Equally the smallish carb bore will restrict the top end performance a bit compared with an open venturi.
'ffkiwi'
The quality seems to be variable. The first thing I would do is remove the backplate (it should have an O-ring seal and be quite easy to unscrew if its like its predecessors) and check for machining swarf in the crankcase. If there is any remove it obviously! [and it would do no harm to swab out the crankshaft bore with a cotton bud while you're at it].
AS for fuel-your 20% heli mix is as much nitro as you should consider using at this stage-a bit less (10% nitro) would be better. Oil wise I would add 5 oz of castor per gallon for a safety factor. Once run in it may be OK on all synthetic [but as you should know from this and other forums] there is a greater risk of doing damage during a lean run with an all synthetic mix-and an accompanying engine life issue. You will get a little bit more power on an all synthetic mix compared to an all castor mix with the same nitro %.
If your local environment permits it (your call obviously!) I would remove the muffler for running in. The mufflers on these APs are ridiculously small and restrictive-and will certainly cost you a lot of power -but then you are faced with what to replace them with in regular use! The accepted wisdom for running in ABC type motors (where the design fits are such that the piston cylinder clearance is optimum when the engine is running, and normally 'tight' when the engine is cold) is for short, slightly rich (not blubbering rich) runs of say 2 mins at a time, and lean the engine out to peak for 20-30 secs before backing off rich again, allow to cool down completely, then repeat the process. Again many factors such as the exact metallurgy, the amount of cylinder taper, and the quality of the machining influence the process-but 20 mins accumulated in 2 min runs might well see it fully run in. As a generalisation ABC type setups require less running in time than ferrous metallurgies. The key to the process is bringing the engine up to normal 'peaked' running temperature for short periods, and this is critical to achieving the optimum cylinder fit during the running in process. Running in the old 'ferrous' way-slow, and rich-if done on an ABC motor, will wear it out before running it in! [the engine doesn't get hot enough for the liner to expand appropriately, the piston fit remains tight, wears in, and eventually is too loose when the engine IS at normal peaked running temperature!]
Obviously, wire or fix the throttle at full open during running in, then once the engine is properly bedded down, then you can start fiddling with the throttle idle adjustments. You never know-they may even have set it right at the factory!
One final thing-it is worth experimenting with different glowplug brands and heats-though the good old OS #8 you mentioned previously is as good a place to start as any! The benefit can be as much as 1000 rpm (or a better idle).
I'm guessing that as a ball raced engine, with a possible racing background to the design, the engine will probably want to rev reasonably high and peak perhaps at 16,000-17,000. Even if it is only average in power output-say 0.3-0.4 BHP, this would likely suggest that your usable prop range would be from 8"-7" diameter, and pitches from 4"-6". 9" props are likely to load the engine down to much. Equally the smallish carb bore will restrict the top end performance a bit compared with an open venturi.
'ffkiwi'
07-27-2007, 04:24 PM
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RE: AP.15 Yellow Jacket
Unclecrash-go and check the Tower Hobbies website-there is some information on all 3 AP engines in their product listing-the AP 15 Yellow Jacket is listed as 'discontinued' but there is still some information listed on the engine technical details, recommended glowplug and prop sizes, run in prop and fuel recommendations. My previous guess of an 8x4 for running in was spot on! I note they still have the 061 listed at 39.99 and the 09 at 49.99..........
'ffkiwi'
'ffkiwi'
07-27-2007, 04:48 PM
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RE: AP.15 Yellow Jacket
8x4 for break in. range of props after break in 7x4,7x5,8x3,8x4,8x6. no more than 15% nitro for break in. 20% oil caster or caster/synth mix, never straight synth. after the engine is broken in a fuel containing 25-35% nitro can be used. straight outta the manual.
07-27-2007, 08:44 PM
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RE: AP.15 Yellow Jacket
Thanks guys good info I bought a little bottle of champion 35% for after run in. But my LHS is out of castor oil. If any of you guys are using the champion are you adding extra castor to it? If so how much per pint. Well I can get back to building the fuse on the P51 it looks like the firewall will have to be shoved back a bit.
07-27-2007, 08:49 PM
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RE: AP.15 Yellow Jacket
FFKIWI Im not sure what you mean look for a swarf. 
please redefine swarf. I will take a look at tower for more info on the engine and also clean it out. My cox had a bunch of aluminum shaving in it. Thanks again
please redefine swarf. I will take a look at tower for more info on the engine and also clean it out. My cox had a bunch of aluminum shaving in it. Thanks again
07-29-2007, 05:36 AM
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RE: AP.15 Yellow Jacket
combatpigg I did intend to imply that it WAS a racing engine, merely that from its external appearance it appears to have come from the same stable as the CS/SY/3-leaf. If you had any familiarity with these brands as I have, you would be able to see the resemblance. In anycase, racing engines, regardless of pedigree, rarely make decent R/C engines-for all the reasons you as a competition flyer should be well aware of.
I wouldn't be at all surprised to find, internally, a smaller bore, de-timed shaft, reduced cylinder timing and port area etc, and a low compression head. Alternatively the crankcase die may simply have been reworked, copied, loaned or whatever. Incidentally, my genuine 3-leaf 15, a Chinese clone of the Rossi Mk3, does run very well, but eats plugs even on FAI fuel. A fuel refinements that the Rossi didn't have-a fully contoured shaft port, O-ring backplate seal.Even back in the early 80's, the Chinese occasionally made a good one.............a couple (09 and 15) were up on Ebay about 10 days ago-went for about $40 odd the pair.
'ffkiwi'
I wouldn't be at all surprised to find, internally, a smaller bore, de-timed shaft, reduced cylinder timing and port area etc, and a low compression head. Alternatively the crankcase die may simply have been reworked, copied, loaned or whatever. Incidentally, my genuine 3-leaf 15, a Chinese clone of the Rossi Mk3, does run very well, but eats plugs even on FAI fuel. A fuel refinements that the Rossi didn't have-a fully contoured shaft port, O-ring backplate seal.Even back in the early 80's, the Chinese occasionally made a good one.............a couple (09 and 15) were up on Ebay about 10 days ago-went for about $40 odd the pair.
'ffkiwi'
