What is the general thought on the big singles, (ZDZ 80, FPE 5.8, Brison 5.8) as far as shake or low RPM vibrations. I'm building a GP 330L, and considering a big single. Thanks for any response.

I had a Quadra 75M on my GP 330L for about 80 flights. Being the magneto version with fixed timing, it was heavier (almost 7 lbs!) and "shakier" than many other big singles, but didn't seem to do any damage to the airframe.

I've sold the Quadra to purchase a ZDZ-80 that I plan to use with a quiet can (in that big area begging for cans) now that I have experience with the ZDZ-80 in a H9 33% Sukhoi that I also own.

Once the ZDZ-80 has some time on it, and the low end is leaned properly, it's really pretty smooth.

I have heard here that the big singles get some harmonic imbalance around 2500 to 3500 RPM if I remember right. Other than that, it should be as smooth as the twins. My problem with this is that 3000 to 3500 RPM must be about what is neede for a good level flight...

Hope this helps.

My zdz80 is just as smooth as the 100cc twins.

watch out - this could drive some ex spurts crazy er sumpin--

My latest one is also extraordinarily smooth.
I have found that most of this varience on the 80 single --is simply carb setup.
some is prop -some is fuel!
mostly the carb.
Oh yeh -some is in airframe / engine mount design -or lack thereof.

I know But I figure sinces Ive owned the zdz80 for over a year, and have had and flown twins for a while now, I could make a fair observations

John,
On that note. There was 2 H9 Suks at my field yesterday. One had the 3W80 twin and the other ZDZ80 single. The ZDZ sounded and was so noticably nicer and smoother sounding that I though it was the DA100 before I asked the guy. I'm sure setup had all to do with it. The other comment I have is it flew some much lighter to my eye than the 3W. I was just watching. Both guys are locals and I'm sure I'll see both planes again at the field. Just an oberservation but I would buy a ZDZ 80 S or one used in a plane ect. anytime! No wonder you have improved the way you have John, that combination looks like one of my electics in the air.!~)

Joe

I have a Brison 5.8 in a Ziroli Corsair and really like it. I'm not sure it would be so good in a very light weight plane. However, I have seen some brute 100cc twins also shake a light weight plane pretty hard. The stronger the twin the more impulse power that is produced.

I also fly a ZDZ80RV in a 1/3 scale Super Decathlon and it has about as low vibration as I've seen in a single. It would have to be my recommendation for your application due to it's light weight and low vibration.

Ken