RackPzgr 8.8cm - Panzerblitz I & II

[Imp]

Not disputing or looked into but your premise could well be wrong.

They will most likely have been designed by 2 separate company's & pressed into service, response to effectiveness of allied rockets. Manufacturing is in a bad way towards wars ends so each built its design. Just like say the jets if its designed & works build it not capable of tooling everything to produce the best.

All rockets are inaccurate
I doubt ground attacks bar dive bombing happened much above 490 km/h you have to see & aim at the target.