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Is A 15 enough
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I have a built up warbird ,it was electric and I converted it to a 15 engine,any way I know a lot of combat pilots use a 15 engine for there planes, so maybe someone can help me.with an OS blue LA 15 engine just broke in, I tried a 8x4 nylon grish prop,the plane flys but rather sluggish on take offs and snaps in the air, so I just put a 7x6 Zinger wood prop will this work better, because I dont believe the nylon grish 8x4 was letting the engine reach its 18,000rpm power band,what do you think? I remember when I flew .049 Cox engines with 6x3 props you could see the r4edish white gow of the glow plug through the exhaust holes at full rpm and they could pull those little airplanes .
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RE: Is A 15 enough
for combat and plane of over 900 grams, the 8x4 is the prop to use, because you need the extra pull. rpm will be between 15000 and 16000. I hardly believe a plain bearing engine delivers best around 18000. None of us rev that high, unless using ball bearing engines like the MVVS. The OS plain bearing .15 is rather aenemic above 900 grams. MVVS .15 fly very well up to 1050 grams. (my mvvs .15 uses an 8x3 prop, plane 1100 grams)
What are your plane's data? Span, weight? Typical combat engines for 1/12 scale rules: smal warbirds like mustang, Spit etc having original span less than 12 meters: .15 engines weight >700 grams larger birds span =>12 meters .21 engines, weight >1000 grams if they also have a wing of =>25 square meters or more, .25 engines. weight >1000 grams |
RE: Is A 15 enough
An 8x4 is a bit large for the engine, but not out of the question. Try an 8x3 master airscrew prop. We also used 7x4's for combat, so maybe a 7x4 or 7x5. I think 7x6 might also be a hair on the big side.
The Grish props, if I recall, are very fleixble, right? You might also try an 8x4 master airscrew or another brand if the Grish doesn't work well. Different brands of props in the same size can be radically different, espeically in this size range. How much does the plane weigh, and what is the wing area? |
RE: Is A 15 enough
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the weight is approx 2.5 lbs the wing spand is 40 inches
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RE: Is A 15 enough
2.5lbs on that amount of wing area is going to be a bit sluggish. SSC planes typically have more wing area and weigh about the same, giving a lighter wing loading.
You're going to need to experiment. I think the props I mentioned above might be good starting points, though it will take some testing. If the engine wasn't the .15LA, but instead was a Magnum, OS CV-A, or Norvel, I'd say start with a 7x4 or 7x5 as those engines like to rev more than the LA does. The LA seems happier with larger props, so the 8x3 would be good to start with. All those props being Master Airscrews. Though I've been using the older MAS GF/2 line, I don't know if the GF/3 is going to be better or worse in that size. At least with the 8x3, the GF/2 is still easily available, since Master Airscrew keeps making them for us combat guys flying SSC. (The vast majority of Master Airscrew prop sales in that size are to combat pilots, and we buy a TON of props) |
RE: Is A 15 enough
You could help it out by offing that draggy LG and hand launching. Have you drilled out the baffle in the muffler? That will gain you a few rs.
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RE: Is A 15 enough
ORIGINAL: rrh You could help it out by offing that draggy LG and hand launching. Have you drilled out the baffle in the muffler? That will gain you a few rs. |
RE: Is A 15 enough
ORIGINAL: Montague 2.5lbs on that amount of wing area is going to be a bit sluggish. SSC planes typically have more wing area and weigh about the same, giving a lighter wing loading. You're going to need to experiment. I think the props I mentioned above might be good starting points, though it will take some testing. If the engine wasn't the .15LA, but instead was a Magnum, OS CV-A, or Norvel, I'd say start with a 7x4 or 7x5 as those engines like to rev more than the LA does. The LA seems happier with larger props, so the 8x3 would be good to start with. All those props being Master Airscrews. Though I've been using the older MAS GF/2 line, I don't know if the GF/3 is going to be better or worse in that size. At least with the 8x3, the GF/2 is still easily available, since Master Airscrew keeps making them for us combat guys flying SSC. (The vast majority of Master Airscrew prop sales in that size are to combat pilots, and we buy a TON of props) |
RE: Is A 15 enough
When we originally began trying 2.5# coroplast flying wings for SSC we were using Master Airscrew 7x6s on Magnum .15s.
That was a step up in power, but a lot more weight than our 32" 1.5# balsa flying wings we had been using with .10FPs. To compete nationally meant flying SSC, not open A. The 7x6s will work on a .15, depending on what you want to do. The Master Airscrew 8x3 should rev 17,500-18,000 on an OS .15LA |
RE: Is A 15 enough
ORIGINAL: Alex Treneff When we originally began trying 2.5# coroplast flying wings for SSC we were using Master Airscrew 7x6s on Magnum .15s. That was a step up in power, but a lot more weight than our 32" 1.5# balsa flying wings we had been using with .10FPs. To compete nationally meant flying SSC, not open A. The 7x6s will work on a .15, depending on what you want to do.=============================================== ================== Hi Thanks, I just want my spitfre to fly with better takeoff an in air action, |
RE: Is A 15 enough
Ive never drilled out a baffle, I took them completely out, how many holes do you drill and what size?? r |
RE: Is A 15 enough
15 will be enough
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RE: Is A 15 enough
ORIGINAL: rrh Ive never drilled out a baffle, I took them completely out, how many holes do you drill and what size?? r |
RE: Is A 15 enough
ORIGINAL: whiskey29 15 will be enough |
RE: Is A 15 enough
but on the 15s will you loose on the muffler pressure feed line? r |
RE: Is A 15 enough
ORIGINAL: rrh but on the 15s will you loose on the muffler pressure feed line? r |
RE: Is A 15 enough
hmmmm, idle, idle?? oh yeah when it's not making much noise right before it dies for landing. Don't have a clue since all I ever worry about is not exceeding 17500 rpm when I launch [>:] Isn't there a "No Idle" rule in the combat handbook :) No good info from me about idling[:@]
r |
RE: Is A 15 enough
ORIGINAL: rrh hmmmm, idle, idle?? oh yeah when it's not making much noise right before it dies for landing. Don't have a clue since all I ever worry about is not exceeding 17500 rpm when I launch [>:] Isn't there a "No Idle" rule in the combat handbook :) No good info from me about idling[:@] r |
RE: Is A 15 enough
I'll look when I get home.
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RE: Is A 15 enough
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ORIGINAL: rrh I'll look when I get home. |
RE: Is A 15 enough
Like I can see in that little hole [X(] There's 1/4" of screw outside of the carb body:eek:
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RE: Is A 15 enough
The exact setting of the airbleed screw for best running may vary with fuel, plug, and such. Do the instructions give a starting point?
Also, be sure the hole doesn't get any dirt or congealed oil or anything in there. If that happens the idle and mid-range will go rich. |
RE: Is A 15 enough
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ORIGINAL: rrh Like I can see in that little hole [X(] There's 1/4" of screw outside of the carb body:eek: |
RE: Is A 15 enough
we fly combat with the os .15 la --they turn the best with a 8 -3 master airscrew
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