Can anybody tell me the ideal prop for a YS .53FZ four stroke. The flying I`m doing is just general type with aerobatics, but nothing too radical.

The aircraft/engine package I bought came with a 12 X 8, but a local guy says it should be a 12 X 6. I used an 11 X 7 on an OS .46 2 stroke, and thought that 12 X 8 would be OK for the 4 stroker.

Any advice is appreciated

Thanks guys

I would use a 12x6, my YS-63FZ ran a 12x7 so I would go a hair smaller on the 53---

An 11x7 is too big for a 46 BTW-

I second the 12-6. ....I use 12-8 & 9's on .91 four strokes.

FBD.

Thanks guys for the prompt responses.

I`m an intermediate flyer, but my knowledge is still basic. Is there a ready reckoner table, or something similar, available for prop selection?

For the .46 2 stroke, would you go 11 X 6 rather than X7?

Here's a decent chart....a .45 usually runs a 10-6.

FBD.

13X6

APC....LP13060....Sport-Prop

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Schpankme

Thanks Dave. Great information to have.

Good pic schpankme!!

Good luck, my friend....[sm=thumbup.gif]

Dave.

Schpankme,


Do you happen to have a prop chart indexed by prop load?

This T/F prop chart, indexed by prop diameter, keeps being displayed by well meaning members, simply because no one has yet published a better one....

It can only give you a starting point, but nothing even close to a definitive answer, to the actual range of props your engine can use.

This range is affected by the prop's load on the engine, not its diameter.
This since a 10x8 is much heavier than an 11x4. Yet this chart suggests the 11x4 for a .53 and the 10x8 for an engine as small as a .37...

As far as I am concerned, just guessing will give you just as good an answer, as will using this chart.


My next project...

Hey Dar,

Why don't YOU create a chart for all us idiots since most of us are obviously propeller impaired.

I personally think the TF chart is a great "starting point" and does not indicate gospel, as there ARE many variables.....and your mileage may vary. [X(]

And oh, BTW, I see more than "diameter" listings.....use both eyes.

Gary

If you treat the YS .53 as a .70 or .75 as it should be treated, the chart shows a prop in the 13x6 range, I have run a 12x6 three blade on both of my .53s in the 9,900 rpm range, this would approximate a 13x6. This tells me the chart is OK.

Pay close attention to the fact that prop sizes that are not offered by Top-Flite, in the Power-Point series, are not even listed.

...No more extreme pitches (9x8, if you can call that extreme), no fractional inch props, like 11.5x6, or the 12.25x3.75 are listed.

In short, this chart is lacking as well as incorrectly arranged.

Since Sid Axlerod passed on years ago, this company has never been the same.


The disarray results from this:

Since as we go to larger engines, they need props of a higher load, this chart should have been arranged as a function of rising load.

Instead, it is arranged in rising diameters, along its 'Y' axis.
Within each diameter, the props are arranged with higher pitch and load, as you go further up.

BUT....

The 9" diameter starts from the 4" pitch and rises up to the 7" pitch, with load rising accordingly, as you go higher.
Then comes the 10" diameter, starting from the 10x4..., which offers a lesser load than the 9x7 size, which proceeded it.

It continues with 10x5 - 10x8 props, which again exhibit a rising load, but the next size up is in the 11" diameter range; the 11x4, which offers a lesser load than both the 10x8 and the 10x7, which proceeded it and is about equal to a 10x6...

This is the way this chart is arranged and it is repeated in subsequent diameter groups.

If I were to make a corresponding graph of prop load per prop size, as the props are arranged in this chart, it would resemble a rip-saw blade, with distinct saw-tooth forms.

But since the engines listed in the chart/graph's 'X' axis, are arranged by rising cubic displacement (and load bearing capacity), the props on the 'Y' axis, must be arranged accordingly, with the load rising as you go further up, not grouped by diameters, as it is arranged now.


I think wrote this is my next project...

Dar,

Yes, I agree that the chart is need of updating tp the 21st century, however, my point was....it's fine for a "starting point". Look at TF's note on the bottom left....



I would like to see APC come out with a chart.

You workin' on one?

Hey Gary, maybe we could use the APC chart in an ugly prop contest.

Here are some numbers from my YS .53 FZ with no lowspeed needle, I have one with and one without.
Done today, about 55 degrees F

Fuel--WildCat Pro mix 20% nitro with 18% 95%/5% synthetic castor blend lube.
Hangar 9 SuperPlug Han 3011

Zinger 12x6-10----8,670 rpm it sounded terrible with this prop.

DynaThrust 12x6----10,560

Graupner 12X6--11.360-- this one was a surprise.

Master AirScrew 12x6 three blade---10,320 a pick up of about 400 rpm over the last time I tached it with this prop. about three more hours on it now.

All the 13x6s I have, have too large of holes in them and I have no suitable adapters.

Dar,

As requested, here's a Prop (load) Chart for the YS 53 FZ.

The most accurate load is between 1600 and 1700 however, it looks like any prop up to a load of 1700 should preform well.

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Schpankme

Good info guys, a few punches thrown, but no serious injuries.

Now another question. Is there a chart for equivalents, two, three and four bladed props.

The YS53 chart is particularly relevant, thanks.

Japanflyer, I used one three blade in my test yesterday a 12x6, the 10,320 rpm should make it an acceptable prop, my Saito .56 turns that same prop at only 9,700 rpm.

JapanFlyer....

....I guess the "load charts" are real nice, and the fancy foot work is cool.
The problem is, the crazy prop numbers don't exist, at least not at my
hobby shop. For general sport flying the 6, 7, and 8 pitch props are used.

Walk into your hobby shop and ask for a 10.5-14 prop. (yeah right )
Tell them some Guys on the Internet said you should use that prop.

Dave.

Seems like trial and error are the best method for prop selection. What about just using a tach to obtain the best rpm? If the usable rpm, lets say is 12k is given, would using a blade to achieve peak rpm be an acceptable method, or do you look for a prop that will perform the best at a given rpm. Example. I have a Seamaster that takes more power to lift off the water. Hence, more thrust at near full throttle. Once in the air, I run generally 1/2 to 3/4 throttle, and need less thrust. and what is the difference in thrust using 2 blade vs 3 blade?

In props, There are so many variables, that it is a trial and error process to fine tune the plane's overall performance.

Sometimes you are limited by what props are available to you then there is also the cost consideration.

To get the seaplane off the water is more of a static thrust situation. But as the plane picks up a little airspeed, static thrust is not so meaningful.

Buy yourself a fish scale and make your own static thrust measurements. Then you can tell us what works best for you?

Enjoy

Jim

Thanks for the further advice guys. Maybe I didn't communicate exactly what I wanted to say...my fault.

What I'm asking, is if the manufacturer specifies a prop, and most are two blade, of say, 12 X 6, what would be required in a three or four blade. Obviously still 6" pitch, but what diameter? I don't see it as being the same diameter, but my knowledge, as I said earlier, is not good in this area.

Using a tach to determine max rpm sounds like a good idea, but can you damage the engine by using a grossly mismatched prop, for example, and possibly a silly example, a 14 X 10 instead of a 12 X 6??

I didn't intend opening a can of worms, here, but this is good discussion, and I am learning something.

I'm about to buy a tach. Any suggestions? Horizon have a Hangar 9 tach for about $30

Here's a 3 Blade Prop (load) Chart for the YS 53 FZ.

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Schpankme

Schpank, in the math, are you treating the YS .53 like a .70 or so? As you can see above, my .53 turned a 12x6 MA three blade at 10,000 plus, which is about where Dave Shadel says to run them.

hobbsy,

You just showeed that your "YS 53" used a 12x6x3B @ 10,000.

The chart says it should swing a 11.5x6x3B, where are we in conflict ?

Your test proves I'm under proped on my charts ?

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Schpankme