While having a debate with a close friend and also a WW2 historian, we were talking about the operation performance disappointment of the Bf-110 series aircraft and what were it's actual downfalls. We were wondering if training was the root cause - not taking advantage of it's performance. Then we looked at it performance data... We also got out my Weapons and Warfare book on the Bf-110 how it was performance wise after the BoB it was a sitting duck for the more nimble and faster Spitfire V/IX and the introduction of American aircraft P-47 and early P-38's. We noted the Mosquito as a fast attack aircraft with no gunners in the rear using its speed solely as its saving grace - speed was key to it's survival as a fast-in-out attack aircraft.
Even with the improved engines, the Bf-110 performance lagged but one thing that my friend came up was the weight of the tail gunner, its ammo, gunner support systems including oxygen, longer cockpit frame, seats, armor for rear gunner, and how much all that extra protection was really needed in a 300+ MPH attack aircraft?
So a couple of questions came up - how much faster would the Bf-110 be if the cockpit was greatly shortened, ammo, chair, comms, oxygen system reduced, and its AA guns deleted and how much more nimble would it be?
The hardest part was figuring out how much all that extra weight to support the rear gunner actually took. The AA mount, the actual seat and frame, reduced cockpit size. Delete of the internal comms system. Reduction of the O2 support system (not much but it also means you only need half the O2. The Bf-110 has an empty weight was 4500kg (9900 in lbs) and it also means that reducing the support systems is a complete guess as the airframe would need additional support to hold the rear guns and gunner.
And we listed the weights of the gunner delete:
100kg (220)- Tail gunner
13kg (30) - two MG-81Z's
240kg (530) - standard ammo count for MG-81Z in Bf-110 at 12g per 7.92mm bullet at 12g each.
100kg (220) - supporting framework for MG's
400kg (880) - rear seat and AA support systems delete
Total reduction of weight would be almost a 20% lighter aircraft.

And an further conversation occurred about modelling those changes in a simulator (FS:X) to see what kind of changes would it have on the Bf-110. Of course, CoG is a big impact as it moves a lot more weight forward from the nose guns, but I'm sure some fuel tank adjustments could of been made by putting a self-sealing fuel tank there in that spot, further extending the range.
Questions:
1. Our estimate was around Was our weight estimates accurate for the gunner delete was around 850kg or ~1850lbs...is that accurate or 'close enough'?

2. Operationally, the Bf-110C-4 flew at around 12-13000lbs loaded with max ammo fuel and bombs. So how much difference does 1800lbs mean on a plane that flies for combat at 12500lbs? Not much, but once it does its job, what kind of fighter would 1800lbs make?
3. If the Bf-110 was a single seat attack aircraft with the weight reductions, how effective would it have been?
4. Considering the potential performance gains of removing the rear gunner, why was the BF-110 equipped with one?
5. Finally - how truly effective was a fast-moving aircraft with a tail gunner?