1/5th scale, is the scale all Byrons WWII stuff was. Most Giant scale stuff today is 1/5th or even 1/4, or larger! My Spitfire was 1/5th, 82", designed for 30cc engines, or 160 class electric, (mine.) At 21 lbs, it would do over 100mph in a shallow dive, and zoom vertical for almost 500ft. Most of todays 3D aircraft are in the 80-100" class, and can hover on the prop and dance for as long as the pilot wants to maintain, then climb straight out effortlessly. These are all 2stroke multi-cyl engines, or electric powered.
TuFun, your Me-109 is in the 1.2m .15 size class, I have 4 of those, all foam/electric, with full flaps and retracts. MkIX spit, F4U Corsair, T-28 Trojan, P-47 Razorback Thunderbolt.
I also have a 1/6 scale F7F Tigercat, electric powered by 2 1.20 class electric motors, turning 3 blade 9x6 props. At 21lbs, it is a very strong flyer.
And, I have two 2.1m wingspan, .45 class electrics, all foam Cessna 152 and CarbonCub (modern J-3 Super Cub) that are wildly aerobatic, while also so gentle they are excellent trainers. We use them as demo aircraft for spectators to fly (with buddy-box setup) at shows.
Craig, I want to get Ziroli's big D-18/C-45 Twin Beech.
The F-4C Phantom in my avatar is electric/foam, with full retracts and flaps. I it is 51.25" wspn. 61" long. Over 110mph.