Hi guys, let me toss my two cents worth of understanding (probably overpriced ) into this.
Most ships mount two impeller rings, one forward and one aft. Each ring is made up of BOTH Alpha (essential for a Warshawski sail) and Beta nodes.
If a ship loses even one Alpha node then a balanced sail can't be generated, hence we had the issue in HotQ where
the DD HMS Troubadour was unable to enter hyper and the grav wave because she had one Alpha node damaged and unrepairable or replaceable locally and couldn't generate the sail necessary to protect her once in hyper and the wave Yeltsin's Star is in but CL HMS Apollo could even though she otherwise had BIG holes shot through her because all of her nodes were left intact.
My understanding is that impeller drive ships can generate wedges even with Alpha or Beta nodes damaged or shot away or even one full ring out of two knocked out with a commensurate loss of power and acceleration.
Again, just my understanding.