A friend had one with a Zenoah G20 for power, more than adequate for the airframe. The Hawk flew extremely well, no bad habits. As with any biplane some power required right to flare. Any loss of power requires a steep approach to maintain airspeed.

I had the GP Stearman PT-17 with a G23. Flight performance was very similar. Both flew very scale like with ample reserve power.

More power is required if you want all out aerobatics. I am considering 40cc in a Super Stearman to achieve that. The Hawk would be great too and there is plenty of room in the cowl.

Don't hesitate to use heavier engines like Zenoahs in these bipes as the nose weign is needed. Using lighter engines require up to a pound of lead to balance.