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Sep 12, 2010, 07:34 PM
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Discussion

High Performance propeller for Evolution .52nx


Hello,

I have an Evo .52nx on my Sundowner, with an Evo 12x6 prop and 15% Omega fuel. What's a good prop to get maximum airspeed out of this engine? Also, please note that I'm switching over to 15% Cool Power.

Thanks.
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Sep 14, 2010, 11:01 AM
Garry
Try a 11-6 or 11-7, not sure if the Evo props have an 11-7 if not use an APC. Maybe even try a 10-8 APC
Sep 14, 2010, 07:06 PM
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Thanks, I'll give it a shot. This plane deserves as much speed as it can get.
Sep 14, 2010, 10:07 PM
Airplane Gearhead
I would suggest a 10 x 7 APC and to stick with Omega...the Castor in the Omega will at least slow down the rust. Stock Evolution bearings aren't all that great, and need all the help they can get.

If you can find a Tower / Aquacraft / GMS muffler, it will give you a substantial boost in top end r.p.m. for relatively little cost. (typically arounf 15 bucks)
Sep 14, 2010, 11:00 PM
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Isn't 10x7 too small? What's the basic prop physics? Lowering diameter gives you greater rpm, increasing pitch gives you greater thrust or something like that?

The cowl has been custom cut for the stock muffler, so I don't wanna change it. But I think I'll remove the baffle.
Sep 14, 2010, 11:22 PM
Garry
Using a smaller diameter prop will in crease the rpm and the pitch gives it the pull. Think of the prop as a cars transmision, lower pitch like an 12-6 is low gear and will only go so fast. You need to shift gears so you go up in pitch but to keep the RPMs up or increased, you need to go to a smaller diameter. I am leaning towards the 10-8 and maybe try the 10-7. And yes get rid of the baffle if you are not worried about noise. I use to run a 9-8 on a Webra speed 50 in a prop jet, at the time it was the fastest plane in the club.
Sep 15, 2010, 08:40 AM
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Sounds good. Let me start with an 11x7. That doesn't sound like too drastic a change.
Sep 15, 2010, 06:51 PM
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Tried the Evo 11x7 with the baffle removed. Had to richen the needle three-tenths of a turn. Speed increase is pretty noticeable. I think this prop size is perfect, 10 would be a bit too small for this model, lookswise.
Sep 26, 2010, 04:57 AM
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Now that I have tasted 100 mph, me thinks I'm greedy for some more, tee hee . I've ordered a 10x8 evo prop
Last edited by Mtn_Commando; Sep 26, 2010 at 10:56 AM.
Sep 26, 2010, 10:56 AM
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oops, i meant 10x8
Oct 02, 2010, 06:16 PM
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I tried the Top Flite wooden 10x8. The engine didn't like it. It ran inconsistently and started overheating after 4 minutes. Didn't get any significant speed increase either.

I'm thinking of swapping the engine out for a Magnum 60, with an 11x8 or something.
Oct 02, 2010, 07:33 PM
Airplane Gearhead
Top Flite wood props are very crude / inefficient in comparison to APC props.
Most wood props, by necessity, have thicker airfoils (needed for strength) and thus put more of a load on the engine than a thinner (and stiffer/stronger) composite APC airfoil blade.

Like I mentioned in an above post...try an APC 10 x 7 and you will notice a substantial improvment. The 10" dia. is plenty big enough, disc area wise. Some guys are running 9.5" dia props with their Jett engines.

Install a Tower / Aquacraft muffler (15 bucks) and you'll think you have a whole 'nuther engine on there...

I have 2 of these engines...they like to rev....the stock muffler is junk...
APC 10 x 7 is about 3 bucks...

Oh, and IMO, stick with the Omega fuel...unless you like changing rusty bearings.
Last edited by proptop; Oct 02, 2010 at 07:54 PM.
Oct 02, 2010, 10:08 PM
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That's interesting. I thought the lighter weight of the wooden prop would put less load on the engine. Actually, I'm big on aesthetic. The only reason I picked the Top Flite is because it "looks" good (when not spinning of course ). That's also why I picked an Evo prop for the 11x7 even though it flexes quite a bit.

But, now I want a more substantial boost than a prop/muffler upgrade will get me. This plane (Sundowner) deserves it. Jett is out of my budget. Thinking about a Magnum.
Oct 03, 2010, 07:43 PM
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proptop, looks like the aquacraft muffler is discontinued. any alternatives? how about a tuned pipe (tho i've never used one before and I don't know how they work).

also, you suggested APC 10x7. Did you mean 10x8? because I already have 7in pitch with the 11in diameter. So going down to 10in diameter, shouldn't/can't I increase pitch an inch?
Oct 03, 2010, 08:08 PM
Airplane Gearhead
The APC (gotta be an APC) 10 x 7 just seems to "work"... It just happens to be a good balance between diameter, pitch, and over-all blade design that just sorta "clicks", ya know what I mean? If you can get that .52 revving to around 14 - 15K you'll see a lot more speed than you are now.

You can get the new Evolution tuned muffler (anodized blue) that was developed for the new Evo .60 (the engine they recommend for the H9 Phoenix 7 ARF and the just released Jakal ARF) it is designed and manuf. by Dubb Jett...it's essentially the same as a Jettstream or Nelson Ultra Thrust tuned muffler...but instead of 15 bucks like the Tower, it's about 60.00 (but IMO worth it)


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