| Azothath |
In a recent thread - - {assume AoN unless stated otherwise}
DnD3.5 Hippogriff on d20srd Str:18, HD:3d10+9, load:lgt 300, med 600, hvy 900.
DnD3.5 Carrying Capacity
STR 15 -> Lgt:66 lb. or less, Med:67-133 lb., Hvy:134-200 lb.
STR 18 -> Lgt:100 lb. or less, Med:101-200 lb., Hvy:201-300 lb.
PF1 Hippogriff on AoN Str:15, HD:3d10+6, load:lgt 198, med 399, hvy 600.
PF1 Carrying Capacity & Encumbrance Effects {identical}
so you can clearly see the *3 scalar for Large size was used in both cases.
It's rather unrealistic as is the game model.
In game terms a scalar would have to be added to 'natural fliers' and another for 'magical flight', then the spell Fly and Overland Flight examined as spells generally operate off caster level or spellcasting ability bonus. Encumbrance rules for fliers would have to be created which would impact Fly Checks and gaining altitude. If you go to all that trouble then you'll have to check the body mass of natural fliers and lessen it... it's a good topic for the Homebrew forum.
The quadruped carrying capacity is what it is and I don't think it's worth fooling with in *this* thread but let's say it's the Maximum upgrade for flight carrying capacity herein.
Carrying Capacity & Encumbrance effects on d20pfsrd
Fly Skill
Spells - Glide:T2, Fly:T3, Overland Flight:T5
From reading(Birds, Raptors) Birds lifting weight about half their actual weight is considered reasonable. Wing span and design, wind conditions and terrain are factors. Champion lifters do about 1.6* to reportedly *2 their body mass. The second reference gives body mass of the bird as well as lifted weight.