Just saw Graupner's Su-31 in model shop.

[link=http://www.shop.graupner.de/webapp/commerce/command/ProductDisplay?prrfnbr=281987&prmenbr=1081&lang=en]Graupner Su-31[/link]

They are recommending OS 46LA or "4-stroke motor of around 11,5ccm"

I was thinking of Magnum FS 61 AR, I can get it for very good pricing.

Would this be enough ? Or step up to Magnum 80 FS AR ?
Price difference is minimal but 80 is 200 grams heavier.

Any help appreciated.

They claim an all up weight of 3.2Kg (7 lbs). If that's true then you'll want more engine than a 46LA... Depending upon the vertical performance you seek the Magnum 80 4 stroke may not be enough...

If I had to choose between the engines you listed I would go with Magnum. I really prefer 4 stroke glow engines in my aerobats...

100 saito this is a sport plane and you need verticle performance but you will need throttle control!!

Yes, I know what they claim on weight, but...

Friend of mine bought their Extra 330 which is same claimed weight and with
MVVS 15ccm it came at 2.4 Kg. Dimensions of plane are roughly the same...