We have done some noise testing, but we don't have very sophisticated methods to measure it. Pete B. would be able to give you a more detailed answer to your question however.
My best guess for you would be that you won't be able to use a 10 or 11" prop at your field, they both wind up very well. The 12 and 13" props are probably getting closer to your needed sound range. If I'm able to, I will try to get some sound measurements, but it's ~30°F here so it might be a while before I'm able to get any figures for you.
If you contact Horizon UK they might be able to help you faster and they're more knowledgeable about your noise restrictions!
Originally Posted by BrumBob
Hi Jimmy, I'm in the UK and have an engine on order so I'm eagerly awaiting their arrival on our shores. What I would be interested in is any noise test figures you have, if you have a comparison with another brand even better. If you have figures at 7 metres even better still.
The club I fly with have quite strict noise limits so I won't be able to run the engine in in the air using a 10" prop, not a chance! I'd be hung drawn and quatered for that!