Right
达 supplies the sound — dá shifted to tà, only tone-and-aspiration differs.
达 itself shows
辶 (walk) +
大 (big stride), meaning 'to reach, arrive'; here the meaning doesn't carry. Pure phonetic. The simplified
挞 replaced traditional
撻's right-side
達 with the simpler
达, keeping the sound. Common compounds
鞭挞 (whip),
挞伐 (whip-and-strike, attack).