"I have not seen an instance, where I have worked out both cases for actual performance, where the dry runway requires more thrust or a lower V1. maybe you can come up with a real-world example... "
If you're looking for real world examples or comparisons, and, seeing as you are working out actual performance, try this for a convincing demonstration -
Calculate the Wet runway performance as normal (that is, with credit for reverse thrust for the RTO, and a 15 ft screen height for the GO case), and then do the same calculation for the Wet runway for Reverse Inop, and for a 35 ft screen height. NOW you have a direct comparison between the requirements for a normal takeoff and that with the allowed concessions. You might be surprised at the huge difference. I routinely produce such RTOWs as a series for each runway, and more often than not, Reverse Inop keeps the aircraft on the ground.
If the legality of using Wet runway data on Dry runways is doubted, then consider this -
(1) Does a Dry runway takeoff allow credit for Reverse Thrust during a RTO? I think not, the law does not allow it.
(2) Does a Dry runway takeoff allow a screen height of 15 ft for a continued takeoff? I think not, the law does not allow it.
If you use Wet runway data on a Dry runway, you're doing exactly what I've specified here, and the law does not allow it.
During a Wet runway takeoff, rolling friction is increased slightly, but not to the point where the continued takeoff suffers significantly using normal Dry runway V-speeds. During a Wet runway Rejected takeoff, braking efficiency is significantly degraded, and this component of the takeoff inevitably becomes the most limiting. As a CONCESSION USING THE LAST AVAILABLE RESERVES, V1s are reduced, and Reverse thrust taken into account. The rejected takeoff, then, uses all of the available margins with no reserve. Because of the lower V1, the OEI acceleration from Vef to Vr and through to V2 is much longer, and that's where the reduced screen height to 15 ft comes into play.
I notice one poster bringing up the 15% additional stopping distance required with no reverse thrust. Not sure which direction where the post was coming from, but if an aircraft does NOT have a reserve means of stopping (e.g. Reverse Thrust or a Braking Parachute), a 15% penalty applies to the ASDR during certification. Was that where you were coming from?
Regards, and Merry Christmas,
Old Smokey