I've had this airplane in my build list for awhile now. I've seen it attempted a few times as-is with poor success and one time with a vertical on the tail... cheating.
The idea is that Blohm and Voss nearly always approached aerodynamic design with an open mind. They typically used proprietary airfoils on their aircraft. This is apparent from their single entry in the
database that uses a foil I've never seen. So, in the spirit of their open mind and given the limited drawing and never a mockup ever made... let's define some assumptions.
This was intended to be a
fighter-bomber and a fast one at that. There were no defensive guns incorporated as it's speed in excess of 400MPH was to be its main defense. With a bomb load of 2200 pounds this was indeed a true raw-power aircraft.
Airfoil
Being proposed in 1942, it can be assumed that the Germans were then privy to the work that the NACA was doing in airfoil analysis and collaborative German work would have lent itself to airfoils that incorporate laminar flow as a means of drag reduction. The P-51 Mustang incorporates this method and was prototyped in 1940. Further still, the B-24, incorporating the Davis airfoil, was revealed to have the same laminar flow properties along with a high amount of lift for heavy bombing runs. Given these historical facts we will be incorporating a Davis airfoil for this model.
Stabilization
A general rule of thumb for model aviation states that for trainer-style aircraft the H-stab should be around 15-20% of the main wing area and the V-stab should be roughly 33% of the H-stab area. Measuring out the profiles of the 3-views available it gives me an H-stab area of ~11% and V-stab is at 25% of the H-stab. Since this is not a conventional trainer style we will be lenient in these figures. For a fighter, the 11% is a fairly good number comparing to other heavy fighters of the era such as the P-47. The vertical area is completely insufficient in respect to a safe margin for yaw stability. Further still, the yaw moment is so close to the neutral point that any rudder deflection will not yield much control. These are clear observations when you look at the math. It will never fly as-drawn. Therefore I'm sure Dr. Voght would have realized this and increased the surface area to stabilize yaw. I will increase the area however, Rudders are not likely to be incorporated as they would still serve no purpose. Yaw control will be under the authority of thrust differential.
The picture below is a model that I never completed of this project for RealFlight. You can clearly see the deviation on the vertical stabilizers. The drawings also do not indicate where the flap/aileron separation was intended to be, therefore they will just be split in the middle.
Also of note is the idea of a bomber. This could be a simple attack bomber but with such a bomb capacity, it could also serve as a dive bomber, thus having better precision for key targets. The last of the dive bombers fr the US was the SB2C Helldiver, which had a bomb capacity of 2000 pounds, or about the same intended load for the P.170. Tail buffeting in dives was a major problem for this style of attack and both German and US solutions were to utilize split-flaps to be deployed during high-angle attack runs. It makes sense as a means of creating drag to control speed and help the airplane track straighter through differing densities of air as it dives. I will attempt to incorporate split flaps in my design as well.
Ben has graciously offered to help me with developing plans. I could do it but it would take me far longer than his skills.