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Best Prop?

Old 04-20-2012, 11:30 AM
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TampaRC
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Default Best Prop?

Coxengines.ca bases their engine rpm's on 5x3 props (they don't say black or gray).

Is the Cox 5x3 considered the best prop for engines such as Sure Start .049, TD .051 and Norvel .061 ?

Or do you guys recommend a different brand and size for best overall performance/thrust ?
Old 04-20-2012, 12:44 PM
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nitroairplane
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Default RE: Best Prop?

What kid of flying are you doing.
For general flying and running purposes I use the black 6x3 on most 1/2a glow engines.
Old 04-20-2012, 03:30 PM
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EX Model Engines
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Default RE: Best Prop?

If you are looking for the best performance I would recommend this one:

http://www.exmodelengines.com/produc...cat=257&page=1

A 6x3 is a good all around flying prop, especially for sport type applications.

Perhaps the most important thing you can do to maximize performance is properly balance the propeller, no matter what size or type. An unbalanced prop will cause a serious decrease in performance. This is a pretty good tutorial:

http://www.youtube.com/watch?v=N02NHYrpA0g

Regards, Matt
Old 04-20-2012, 05:24 PM
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Default RE: Best Prop?

Best propeller IMO is APC you have to choose the measures for your needs but start from 4/4.5 for supreme speed performance 5/5 for some serious speed up to 6/3 or 6/4 for sport fly
Old 04-20-2012, 07:05 PM
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Default RE: Best Prop?

I've never balanced a 1/2A prop ever and I believe that I've flown 2 of the fastest 1 cc powered RC planes ever built.
Old 04-20-2012, 09:05 PM
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DeviousDave
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Default RE: Best Prop?

The best 1/2A props are not Cox props. Start with APC before going to the specialist suppliers out there like Larry Driskill/Kitting it Together.
Old 04-20-2012, 09:22 PM
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Mr Cox
 
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Default RE: Best Prop?

Both 6x3 and 6x4 are too large for 1/2a engines, even the 1cc Norvel. Large props will just bog the engine down and make them picky on the needle setting etc. APC has a nice selection but others work too, like the cox 5x4 which can take a beating.
Old 04-20-2012, 10:37 PM
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DeviousDave
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Default RE: Best Prop?

Probably the best advice I have ever gotten for a 1/2A engine came from the instruction sheet for the VA .049 back in the 1990's.... Paraphrasing, it said to forget everything you know about 1/2A props because they were designed for a 50 year old engine, and to treat the VA like a miniature F1C engine with light loads and high RPM.

Norvels would be much the same, it doesn't take a rocket scientist to see how much more a Norvel likes light prop loads when you see what a huge jump in RPM you get going from a 6-3 to a 5-3, and a 5-3 is a pretty heavy load for a ComBloc engine. The Russians have a different approach than we do given that they had no access to nitro, and no access to foreign engines behind the iron curtain. When the curtain fell, a lot of unemployed, frustrated defense workers had time on their hands and they tried some interesting things (Like the VA's variable timing feature) to be competitive. At the end of the day, while we struggled with Cox motors up thru the 1990's, they found that high RPM motors with props that were closer to 'square' were the way forward..
Old 04-21-2012, 03:24 AM
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nitroairplane
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Default RE: Best Prop?

A lot of conflicting info
Balance props, don't Balance props.
6x3 is good, 6x3 is too big.
Cox, APC
I dunno what to beleive lol
Old 04-21-2012, 04:53 AM
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Larry Driskill
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Default RE: Best Prop?


ORIGINAL: DeviousDave

Probably the best advice I have ever gotten for a 1/2A engine came from the instruction sheet for the VA .049 back in the 1990's.... Paraphrasing, it said to forget everything you know about 1/2A props because they were designed for a 50 year old engine, and to treat the VA like a miniature F1C engine with light loads and high RPM.
I searched for the advice Dave refers to and came up short. Here is what I could find:

"Top performance depends on using the proper propeller. When choosing the prop remember that these engines need to turn up higher than older style engine to be in their proper power band. Some 1/2a props of the nylon and plastic cast variety have crooked, out of true hubs. If the spinner / prop bolt is wobbling, true up or discard that prop."

"Propellers (VA MKII)
Many of the newer 1/2A size engine designs rely on high RPM for the increase in power over older designs. A smaller propeller than was normally used with older engines is generally necessary. For Control Line Combat, 4.25 X 3 propellers are common. For Free Flight 5.25 X 2.5 is a good initial choice. For R/C Racing a 4.6 X 3 or 4.2 X 4 is a good starting point. Normal RPM range for good performance is 25,000 to 30,000. Choose your propeller size and style to keep the ground RPM in this range.

"Propellers (for the VA MKII RC version)
Many of the newer 1/2A size engine designs rely on high RPM for the increase in power over older designs. A smaller propeller than was normally used with older engines is generally necessary. A 5.5 X 2 or
6 X 2 is a good starting point. Maximum power will probably be obtained at a higher vice lower RPMs. "

Old 04-21-2012, 05:10 AM
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Larry Driskill
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Default RE: Best Prop?


ORIGINAL: nitroairplane

A lot of conflicting info
Balance props, don't Balance props.
6x3 is good, 6x3 is too big.
Cox, APC
I dunno what to beleive lol
Yep, I also see conflict. And what I posted above is for the VA MKII and is not all applicable to Cox engines.

Going back to Tampa's original . . . he did not say what flying, or what Cox engine, he was interested in, did he? So we have wandered and that is probably OK too.

When I ran TeeDee .049s in 1/2A Controlline Combat, I usually used the black Cox 5X3 (Rubber Ducky). I ran it full length. Well, full length except for the small amount I clipped off the tip one blade with a single edge razor blade to balance the prop (sorry Pigg). (Balancing 1/2A props {usually 4,5,or 6" in dia.} is not usually as important as balancing longer props like the 8,9, and 10 inchers on a .40)

On reed valves I ran the 5X3s and sometimes 6" props.

I am under the impression that Texaco flyers run even longer props on their stuff.

So, it depends . . . on the particular engine, the type plane, the weight of the plane, the weather, the fuel, and your tolerance for broken/blown-up engines and maybe how much prop generated noise you can stand.
Old 04-21-2012, 06:21 AM
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combatpigg
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Default RE: Best Prop?

I think the rubber 5x3 Cox prop is the most versatile.
All you need are a few of them to last a life time.
The 6x3 needs to go on real healthy .049-.061s if you want good thrust.
The 5x3 will deliver more speed on most planes that aren't too big and fat.
APC props are fantastic, but easy to break. The difference in performance over the unbreakable Cox black rubber props might not be enough to justify the extra cost.
6x4 is a good size for .074s, .10s, .12s...but too big for .061s and .049s. It's a slight overload.
7x3 and even 8x3 work well with Norvel .074s
If the chosen prop doesn't run smooth or track well, I'll investigate...but this is rarely a problem.
One of the smokin'est runs I ever got out of a TD.049 on a speed plane was with a hand carved maple 4.2x4 prop with wafer thin, toothpick blades.
In the middle of the flight the plane went from fast to noticeably faster...it sounded like the engine got a shot of nitrous. Once the plane landed I could see why, one of the prop blades broke off at half span. I fired it back up, it ran smooth enough and I continued to fly it like that until it broke the other blade upon landing. I never did duplicate that scenario on purpose.

Old 04-21-2012, 07:21 AM
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nitroairplane
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Default RE: Best Prop?

I started using these new yellow rubber sucky props from Bernie.
The 5x3 ones and they are great for sport flying but the blades like to
Pull
Forwards occasionally and flatten out a tiny bit.
This I found most noticeable on 061s.
And the space hopper.
Old 04-21-2012, 07:23 AM
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nitroairplane
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Default RE: Best Prop?

I am sure they must be the toughest props ever made.

Old 04-21-2012, 09:25 AM
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combatpigg
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Default RE: Best Prop?

Just a quick note about props and tuning.

Any time you put on a prop and find that the needle valve needs to be opened up, you are working in the right direction to finding the engines' peak HP.
Usually this only happens when you go down in size / pitch.
Of course you can take this too far......
The opposite is true when you need to close the needle valve a little after changing props.
Increasing the load too much will require lowering compression, which is also a sign that your engine is over-propped.
Running these engines in large models may require a compromise between acheiving max HP and choosing the prop that pulls the plane the way you like it.
All this "rambling on" is over complicating things and is sort of irrelevant unless you enjoy talking about 1/2A engines and props.
Old 04-21-2012, 10:15 AM
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Default RE: Best Prop?

the best 1/2A prop for sport flying is the APC 5.7x3 prop. gives enough thrust and pitch yet allows it to rev because of the narrow blades. This is a good prop for ya.

I have ran Cox 6x3 on cox engines also just depends on the plane. those really small props work best on a plane under 12 ounces and 100 sq inch wing or less.

the 6x2 on the novel type give good thrust also but no real speed good for gliders and free flight stuff.
Old 04-22-2012, 10:28 PM
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DeviousDave
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Default RE: Best Prop?


ORIGINAL: Larry Driskill


ORIGINAL: DeviousDave

Probably the best advice I have ever gotten for a 1/2A engine came from the instruction sheet for the VA .049 back in the 1990's.... Paraphrasing, it said to forget everything you know about 1/2A props because they were designed for a 50 year old engine, and to treat the VA like a miniature F1C engine with light loads and high RPM.
I searched for the advice Dave refers to and came up short. Here is what I could find:

''Top performance depends on using the proper propeller. When choosing the prop remember that these engines need to turn up higher than older style engine to be in their proper power band. Some 1/2a props of the nylon and plastic cast variety have crooked, out of true hubs. If the spinner / prop bolt is wobbling, true up or discard that prop.''

''Propellers (VA MKII)
Many of the newer 1/2A size engine designs rely on high RPM for the increase in power over older designs. A smaller propeller than was normally used with older engines is generally necessary. For Control Line Combat, 4.25 X 3 propellers are common. For Free Flight 5.25 X 2.5 is a good initial choice. For R/C Racing a 4.6 X 3 or 4.2 X 4 is a good starting point. Normal RPM range for good performance is 25,000 to 30,000. Choose your propeller size and style to keep the ground RPM in this range.

''Propellers (for the VA MKII RC version)
Many of the newer 1/2A size engine designs rely on high RPM for the increase in power over older designs. A smaller propeller than was normally used with older engines is generally necessary. A 5.5 X 2 or
6 X 2 is a good starting point. Maximum power will probably be obtained at a higher vice lower RPMs. ''

Gimme until tomorrow to get home and pull out the instructions, I have 8 or 10 of these Mk1's from two or three importers. IIRC, these instructions are about 10 pages long and quite detailed.
Old 04-24-2012, 07:55 AM
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DeviousDave
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Default RE: Best Prop?

Yep, I remembered it about right:

Old 04-26-2012, 10:23 AM
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TampaRC
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Default RE: Best Prop?


ORIGINAL: airraptor

the best 1/2A prop for sport flying is the APC 5.7x3 prop. gives enough thrust and pitch yet allows it to rev because of the narrow blades. This is a good prop for ya.

I have ran Cox 6x3 on cox engines also just depends on the plane. those really small props work best on a plane under 12 ounces and 100 sq inch wing or less.

the 6x2 on the novel type give good thrust also but no real speed good for gliders and free flight stuff.

I am flying sport planes such as HOB P-47, ACE Simple P-51 and Ace Mach None. Looking for speed using Cox TD .051, Norvel .061, and slightly modified Cox .049 easy starts or whatever they were called.

These planes are all over 12 ounces. I'm gathering that I should be in the 5" diameter range from what you guys are saying.

Old 04-26-2012, 01:50 PM
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Default RE: Best Prop?

Yup my recommendation, get a few different brand and size props and future out what you like best for the plane a good compromise between speed and climb.
Old 04-26-2012, 09:37 PM
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DeviousDave
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Default RE: Best Prop?

If you are running a TD .049 on a sport plane, try the new APC 5.7-3. Would work as well on a Norvel but a TD has the torque to use it well.
Old 05-04-2012, 12:39 PM
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Default RE: Best Prop?

I've run a couple of Ace Pacers, almost identical to the Mach None, with a TD 051 on pressure and tried most of the props made. The plane flew the best with an APC 5.7X3. Might have made more power with a smaller prop, just didn't fly the plane well. Have to agree with CP on the rubber ducky 5X3 on the reed valve and sure starts. Unless the plane is a real dog, then an APC 5.5 X 2.5 will sometimes hoist the turd skyward with a surestart.
Old 05-06-2012, 02:33 PM
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Default RE: Best Prop?

Hi hllwdb,

"Hoist the turd skyward with a surestart"...

Now THAT is funny ! ! !

HeHeHe

Take care,
Have fun,
Dave'crosscheck'Fallowfield
Maac 6437
Unabashed Combat Team
Old 05-06-2012, 04:03 PM
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DeviousDave
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Default RE: Best Prop?


ORIGINAL: hllywdb

I've run a couple of Ace Pacers, almost identical to the Mach None, with a TD 051 on pressure and tried most of the props made. The plane flew the best with an APC 5.7X3. Might have made more power with a smaller prop, just didn't fly the plane well. Have to agree with CP on the rubber ducky 5X3 on the reed valve and sure starts. Unless the plane is a real dog, then an APC 5.5 X 2.5 will sometimes hoist the turd skyward with a surestart.

APC redid the 5.7-3 a few years ago to make the blades thinner and a little narrower. Looks more like one of the electric props they make than one of the plastic paint stirring sticks they make for 1/2A. Do you know if you had one of those props or the older style?
Old 05-06-2012, 06:04 PM
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Default RE: Best Prop?

I had a Norvel that wouldn't even run with a 6-3" .  I was getting pretty mad at it, and put a smaller one and it went great.  Every motor, plane and desired performance requires a different prop.  A free flight or stunt plane, may want a 6-2, a 5-2" on a reedy it may go over 18,000 rpm and cause the reed to flutter and max out, a 4-7" may work good on a clean speed plane with a pipe-unless the pipe is too short, a Fora may require something much smaller than Cox stuff.  Get your hands on as many props as you can and try them all to see.  That is what I do.

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