Mytextsample <- "aaaaabb cccdddd eee adssdada ooeoeo ososs ksdkd
  ooeresso osososososos krrr dkdkkd odlcjs kdcmcmc ddddd dmssss"

dat <- unlist(strsplit(Mytextsample, " ")) # unlist is here to convert to a vector
dat <- split(dat, ceiling(seq_along(dat)/10))

out <- sapply(dat, function(x) paste0(x, collapse = " "))
out