As far as I am aware the HE111 ( union) and the 323 glider were not developed for use when the invasion was being plannedand only came into service afterwards when events had moved on. I do think ( and don't doubt) that initially Hitler did intend to invade and if circumstances had been right would have done so and preparation did start with that in mind but the nature of the preparations would have cast serious doubt on the ability of Germany to mount a successful invasion and highlighted the potential risks of the enterprise. The initial landings might have been possible but potentially at a cost and there is little boubt that the Germans would have been aware that they would only have been able to depend on what they could get across the Channel and anything captured would only have been a bonus and might only have been use at local level. Given the later problems which they encountered with airlifts in the face of an effective enemy airforce it would have been a huge gamble. The advance lines on the map are similar to those seen in Russia easy to draw but difficult to achieve. I don't doubt that there was an initial expectation that invasion had to follow but that this changed durring the course of the summer weeks. The Army looked (quite rightly) to the navy for a lead - an undertaking that they could do it and they looked to the Luftwaffe ( quite rightly) for an undertaking that they could control the the Channel coast over England and contain the RAF and the Royal Navy - this was a cheque which Goreing could not cash , and as the promised easy victory did not appear confidence in Sealion ebbed. The ability to "go" quickly after Dunkirk did not exist and only an overwhelming German ability to invade at that time might have produced success. Fall Green has been mentioned as a diversion from Sealion - even there it was way beyond the ability of the Germans to invade Ireland , dropping paratroops on Long Kesh and at Aldergrove to capture airfields and to back this up with a meaningful landing of troops by sea. Crete was an example of a latter day Sealion type plan - the Germans controlled the air ( which they failed to achieve over G.B.) , the British the sea - no specialist invasion shipping existed and the violence and surprise of the assult would either bring success or threaten failure. Crete was so close and denied an airfield for a day or two longer it would have failed. How likely is that complete surprise could have been achieved ? Whilst the Germans would have been landing on limited fronts they would have been resisted on the same frontage against the background of a potentially disastereous and vunerable supply line. Sealion was one of the few situation in the Fuhrer HQ in which reality dealt with the military issues involved - perhaps this was only possible beacuse Hitlers willingness to "go for broke" was tempered by his desire to square accounts with Russia and end his marriage of convience with Stalin ?