"It doesn't matter at all how long bow, what matters is draw distance and how much energy that distance can give to arrow. Draw distance is equal but recurved mongol bow wins with effective draw distance->recurve
Maximun poundage is equal, both bows can be made so strong that strongest man in world can't draw them. Only thing that matters is how strong the archer was and both trained their whole life.
Longbow was heavier and it is disadvantage, because more draw energy is wasted to accelerate bow instead of arrow.
Conclusion:With mongol bow it was possible to get lot better speed of arrow, it would have been possible to use heavier arrows, but arrow speed would have had lower, no reason to do "that. Faster arrow=better penetration with direct fire.
Longbow was slower bow so smaller arrow would not help because bow mass would have wasted more energy. Instead they had slower but heavier arrow. Heavier arrow is better in one thing, and thats when you shoot it very high and it generates its speed and energy by falling->drag of air takes smaller part of heavier arrows starting energy."
Proffesional english longbowmen could shoot much faster than a mongol archer.