18" Rubber-Powered Contra-Rotating Koolhoven FK-55 - Semi-Start to Finish

Two flights by the 18" rubber-powered Koolhoven FK-55 by Tom Hallman. The model has contra-rotating props via a Contra-Rotating Prop Drive unit (CRPD) designed by Keith Sterner. Unfortunately, the units are no longer produced. Model is loosely based on this 1937 plan & article from Model Airplane News: http://www.hallmanstudio.com/Koolhove... Music: "Loveable" by www.bensound.com

*** 10 steps to trimming a rubber model, by John Koptonak: http://www.flyingacesclub.com/PFFT/Tr...

Balsa density chart with the sweet spot for building light: http://hallmanstudio.com/Balsa_Densit...

Flying Aces Club merchandise: https://www.cafepress.com/flyingacesclub
Center of Gravity merchandise: https://www.cafepress.com/centergravity

For more info on free-flight rubber-powered models, check these websites:
http://www.easybuiltmodels.com/
http://www.volareproducts.com/BUY/
http://www.flyingacesclub.com
Outerzone - https://outerzone.co.uk/index.asp
National Free Flight Society - https://freeflight.org/
Mike Stuart's Flying Scale Models - http://www.ffscale.co.uk/