Is there a graph/table for what the correct size of prop you need for specfic engines/and or sizes?
I saw one in a hobby shop but would like to find one online.
Mike

Tower Hobbies used to have one in the back of their catalog, I don't know if they have one on their web site but it might be a place to check. You might also go to the web sites for the prop & engine manufacturs. ENJOY !!! RED

Try downloading this

[link]http://www.infinityok.com/prop_chart.doc[/link]

Hope this helps

Ken

This is stated in that prop guide:

What would happen if the spinner is touching the prop?

Either the prop or spinner could fail from contact-vibration damage-- with interesting results for anyone nearby.


Prop charts are very general guidelines & not to be taken as absolute. There is a gigantic range of engine HP & performance characteristics, plus substantial airframe effects that complicate prop selection.

For example, in the 40-size engines, there exists nearly 100% difference in output between the weakest and strongest 40-size sport engines currently on the market. That makes for an enormous difference in prop selection for one engine size -- & the charts don't cover it.

Similarly, the airframe & its intended use powerfully influences prop selection. Is it a small clean speedster, a blunt-nosed biplane, a trainer, a 3D type? All of these factors can make a prop chart only vaguely usefull. Use the chart, but expect to do a lot of experimentation to get a good match.

To take it one step further, see what the owners manual says to use. The manual for my 1986 O S Max .25FP said to use an 8X6, 9X5 or 9X6. The 8X6 and 9X6 weren't even listed on that chart for a .25, or for any of the two strokes for that matter.

I probably should have said this when I posted the link to the chart, but this chart should only be used as a broad guideline for which props to use. Different motors may be able to use props that aren't shown on the chart.

Ken

It's not a problem, Ken. It gave me a chance to use the "Read the Manual" line. Besides, who better than the manufacturer would know what prop sizes to start with for any given engine?

No *****e Muslim. I used the chart in the hobby shop and it said 11X4. It over-revved big time. I need to put a 11X6 on it.....

If you told us which engine you have specifically, and which plane its on you might get some very good suggestions based on experience with a similiar setup. [8D]