The interconfessional Chichewa translation (publ. 1999) uses the ideophone thapsa to describe a flopping motion when going down. (Source: Wendland 1998, p. 105)
Philip Noss (in The Bible Translator 1976, p. 100ff. ) explains the function of an ideophone: “The ideophone may be identified with onomatopoeia and other sound words frequently seen in French and English comic strips, but in [many] African languages it comprises a class of words with a very wide range of meaning and usage. They may function verbally, substantively, or in a modifying role similar to adverbs and adjectives. They describe anything that may be experienced: action, sound, color, quality, smell, or emotion. In oral literature they are used not only with great frequency but also with great creativity.”