I know that there is no substitute for trying a prop to determimne whether it is suitable for a particular plane/engine combination. Nonetheless, before I try my latest prop acquisition - - a Kyosho 9x5 - - on my Fox 25 BB, I would appreciate hearing from anyone who has used these unusual props your impression of them for stunt use. Thanks in advance for any comments you might have.
Peter,
Please proceeed with the greatest care. A couple of months ago I gave away a couple of Kyosho electric motor/gearbox combinations that had Kyosho propellers attached. That is the only application I have ever seen for Kyosho-branded propellers. I am not aware of Kyosho making any propellers but those intended for electric flight. E-power props have no business being attached to reciprocating engines. If this propeller was mine I would make cast-iron certain that it was intended for installation on an engine and not an electric motor. The consequences of inappropriate use could be lethal.
Tower Hobby's catalog shows Koyosho props, definitely made for recipro engines. Dunno if what Tower lists is the full assortment but they tend to be too high in pitch for our use. If one matches your purpose, it's worth a try in my opinion. I'd bet a 9-4 Taipan will work better, tho. I'm running one on a Magnum .25. Email me! Steve
Peter:
Your caution is, of course, appreciated. However, as Steve observed in his message, I am pretty sure that these particular props are not for electric application. Not only are they pretty beefy, but they come individually packaged with the most elaborate set of instructions and warnings that I have ever seen. Clearly the Kyosho Corporation has fallen under the spell of my brethren at the bar. The warnings include an rpm limit for each different diameter prop in this series. The limit ranges from 19,000 for seven inch props down to 11,500 for twelve inch props. I have a 9x5 to try on the Fox 25 BB. The limit on this size is 15,000. I doubt that this engine will ever see more than 11,000 rpm. That should leave a more than adequate margin of safety. I'll show it to you the next time I see you.
BUT, extreme caution with any prop is always the rule of the day, especially when trying a new brand/type.