Complex sentence: The fourth prototype, "LV639", was furnished as a paratroop transport, complete with ventral dropping doors; flight testing found that the York was unsuited to this role due to the slipstream wash drawing the parachutes towards the non-retracting tailwheel, posing an entanglement risk.
Split into simpler sentences: The fourth prototype, "LV639", was furnished as a paratroop transport, complete with ventral dropping doors. However, flight testing found that the York was unsuited to this role, due to the slipstream wash drawing the parachutes towards the non-retracting tailwheel, posing an entanglement risk.