Re Ali's comment on speed above. All full size have an airspeed limit for retracting the gear - for instance the Jet Provost has a limit of 125 knots for raising the gear, but once down the limit becomes 140 knots. The Lightning (250 retraction and 280 with it down) nose wheel retracts forwards - if the gear is not selected up quickly enough the airflow prevents it from retracting, and you zoom skywards with the nose wheel sticking down - this always leads to ribald comments from any mates who happen to witness the event! Perhaps we are asking too much of our model systems (flaps also are limited to avoid airframe damage and having too great a pitch reaction), and we should make selection of the services at more modest speeds?