I found this on the net which makes some interesting points .......note I didnt write it.
Events were now leading to a confrontation between the Luftwaffe and the RAF, in which the Bf 110 would suffer heavily. Consequently, sharp criticism of the aircraft, and by extension the entire class of twin-engined fighters followed, well beyond what is justified by the actual events.
It is as well to start by looking at the performance parameters. The Bf 110C-4, a common model at the time, was powered by two 1,100 hp Daimler-Benz DB 601A engines, and had a normal loaded weight of 6,940 kg; so its power loading was 3.15 kg/hp. The Hurricane Mk.I weighed 2,924 kg loaded and was powered by a 1,030 hp Merlin Mk.III engine, giving a better power loading, of 2.84 kg/hp. The Spitfire Mk.I, powered by the same engine, was lighter because of its more advanced structure, and the normal loaded weight of 2,812 kg resulted in a power loading of only 2.73 kg/hp.
The Bf 110C-4 was claimed to be capable of a maximum level speed of 562 km/h at 7,000 m altitude, and 473 km/h at sea level. British test pilots, flying a captured C-5 reconnaissance version at lower weights, measured only 547 km/h at 6,700 m, so perhaps the German figures were too optimistic, but such variations between individual aircraft were common and the test aircraft had been assembled from two wrecks. This was still considerably faster than the 508 km/h at 5,400 m and 409 km/h at sea level of the Hurricane Mk.I, and competitive with the 557 km/h at 4,570 m of the Spitfire Mk.IA. The German fighter also performed reasonably well in the climb, with an initial rate of climb of 670 m/min, somewhat inferior to the 770 and 740 m/min attributed to the Hurricane and Spitfire. Nevertheless it could climb to 5,500 m in 7 minutes, while the Spitfire Mk.IA needed 6.85 minutes to 4,570 m (and the Hurricane 6.3 minutes).
During the battle of Britain, 100-octane fuel was used by RAF fighters. By allowing the Merlin to run at higher pressures and generate 1,200 hp, this considerably improved their performance, especially in climb. That came as an unpleasant surprise for the Luftwaffe. Nevertheless, in terms of performance the Bf 110 appeared competitive enough. Its weakness in combat against the RAF fighters was its manoeuverability, which was good for an aircraft of its size, but no match for the opposition it faced. The wing loading of the C-4 model, 181 kg/m2, was considerably higher than the 123 kg/m2 of the Hurricane and the 125 kg/m2 of the Spitfire, and this resulted in a larger turning circle. The handling of the Bf 110 was quite good at normal speeds, with effective controls and generally pleasant flying characteristics. However, the controls heavied up considerably at higher speeds, and the ailerons were almost immovable in fast dives. But this, it must be said, was a weakness of all fighters at the time, German and British alike.
Overall, the characteristics of the Bf 110 implied that the Zerstörer were at a serious disadvantage whenever they were forced into a defensive position. Their speed and firepower served them well when they made hit-and-run attacks, exploiting their good climb and dive characteristics, while declining to engage in turning combat. Most fighter-versus-fighter combat during battle was of short duration anyway, typically less than half a minute; long dogfights were very rare because they left those who engaged in them in a very vulnerable position, low and slow, and too preoccupied with their target to watch their rear.
When flying Freie Jagd fighter sweeps at high altitude (above 6,700 m) over Southern England, the Zerstörer units demonstrated that the Bf 110 was indeed a dangerous opponent, and could be more than a match for the Hurricane. Unfortunately for the Germans, this was not the pattern of the battle to come. Fighter Command soon decided to avoid contact with the fighter sweeps, and concentrate its attacks on the bomber formations. Then, flying at low and medium altitude, and robbed of the advantage of surprise by radar and the advanced command-and-control system of Fighter Command, the German crews often found themselves at a serious tactical disadvantage. This, of course, also handicapped the Bf 109, but the nimbler single-engined fighter could extract itself from an unfavourable situation with much more ease. The normal reaction of Bf 110 crews was to seek safety in a Lufbery circle, a defensive formation in which fighters fly a ring pattern, each covering the rear of the one next ahead in the formation. While an effective tactic, this could only be maintained for as long as the fuel reserve allowed, and the RAF fighters waited above for an opportunity to strike.
Indicative of how just badly things could go wrong was an attack on Croydon on 15 August 1940. This attack was executed by bomb-carrying Bf 110s and Bf 109s of Erprobungsgruppe 210. Serious damage was done to airfield, but while still in its attack run at low level the Germans were bounced by a superior number of Hurricanes. They found temporary protection in a defensive circle, but finally had to make a break for home; the RAF fighters immediately fell onto their targets, shooting down seven out of the twenty-two strong enemy force.
The Bf 110 also had to take on the role of escort fighter for the bombers, because the fuel capacity of the Bf 109 allowed it only a short stay over England. But the German escort tactics were flawed. (Arguably, they were not much more flawed than some other attempts to provide bomber escort, such as the early efforts of the USAAF.) Too many fighters were ordered to fly close escort, in formation with the bombers; in that position they could do little to defend the bombers and became vulnerable targets themselves. The error was made worse in early September: Against the strong opinion of the fighter leaders, they were ordered to stay closer to the bombers, and even to break off combat with enemy fighters if the bombers were threatened. The Bf 110 turned out to be unsuitable for close escort missions, and losses were heavy.
That said, the often-repeated story that the Bf 110s themselves had to be escorted by Bf 109s is a myth. Tactically, this would have made no sense. The only Bf 110s that were really escorted by single-engined fighters were the fighter-bombers of Erprobungsgruppe 210, which were otherwise too vulnerable with their combat loads, or when making their attacks at low level. Perhaps this, or maybe the complex organisation of the escort fighters around a bomber formation (including formation flying distant cover, close cover, and top cover) gave raise to the story.
Anyway, the failure of the Bf 110 as an escort fighter was just one more nail in the coffin of a doomed operation, but as they had been a much-propagandized part of the German air force, it became symbolic. Its importance should not be exaggerated, for at the height of the battle, Bf 110s were less than 12% of the Luftwaffe's available force, and only just over a quarter of the fighter force. There were many more important factors that doomed the German attempt to subdue Britain to failure: It had seriously underestimated RAF strength, and ignored the importance of the radar and command-and-control network. The available bomber strength was insufficient, and in turn the fighter strength fell short of the requirement to provide escorts in a 2:1 ratio. Aircraft production and crew training lagged behind the RAF. Intelligence and target identification were very poor, so that many bombs were wasted on targets of little importance, and enemy losses strongly overestimated. The range of the Bf 109E was too short, the use of drop tanks was neglected, and the available bombers had small bomb loads and weak defensive armament. Last but not least, the operation itself was handicapped by two conflicting goals, preparing for an invasion by destroying the RAF and forcing Britain to come to a negotiated peace by bombing, and neither was a realistic war plan.
The catalogue of failure should not obscure that the Bf 110 had also found a role in which it was very effective, that of a fighter-bomber. This was especially so in the hands of Erprobungsgruppe 210, a unit that specialized in precision attacks on targets such as airfields, radar stations, and shipping. At the beginning of the battle it operated a number of Bf 110C-6 with a powerful MK 101 30-mm cannon in a fairing under the fuselage, but operational and technical problems lead to the removal of this weapon. The occasional heavy losses demonstrated the need for air superiority on such operations, but a series of successful attacks also confirmed the effectiveness of the aircraft in this role. The large Messerschmitt fighter still had a long and generally successful career ahead of it.