G, the LDR benefit is slightly more than pure geometry due to the use of real steep approach test data in the landing flare segment, and thus there is a further reduction.
The takeoff theory is as you surmise, but from memory the differences were in the thickness of the line, for the same load, but obviously at a higher weight for the RJ100. Therefore perhaps the flap 33 improvement could be quantified by the differences in aircraft ZF weights RJ85 vs RJ100.
Hoppy, that’s interesting; do the values you quote originate from the flight manual?
IIRC the 146 certification (AFM) was pre JAR (pre EASA). The steep approach criterion was a special condition (UKCAA version of a Canadian STOL document) and the 146 certification was read across to the RJ.
I don’t recall any ‘EASA’ AFM; thus wonder if someone has either rewritten the books, or are the values based on EASA approved operational interpretations (EU-OPS)?